List of Titles

Quick View

Observations of diffuse radio emission in the Perseus Galaxy Cluster

- Mungwariri, Clemence

Authors: Mungwariri, Clemence
Date: 2020
Subjects: Galaxies -- Clusters , Radio sources (Astronomy) , Radio interferometers , Perseus Galaxy Cluster , Diffuse radio emission
Language: English
Type: Thesis , Masters , MSc
Identifier: http://hdl.handle.net/10962/143325 , vital:38233
Description: In this thesis we analysed Westerbork observations of the Perseus Galaxy Cluster at 1380 MHz. Observations consist of two different pointings, covering a total of ∼ 0.5 square degrees, one including the known mini halo and the source 3C 84, the other centred on the source 3C 83.1 B. We obtained images with 83 μJy beam⁻¹ and 240 μJy beam⁻¹ noise rms for the two pointings respectively. We achieved a 60000 : 1 dynamic range in the image containing the bright 3C 84 source. We imaged the mini halo surrounding 3C 84 at high sensitivity, measuring its diameter to be ∼140 kpc and its power 4 x 10²⁴ W Hz⁻¹. Its morphology agrees quite well with that observed at 240 MHz (e.g. Gendron-Marsolais et al., 2017). We measured the flux density of 3C 84 to be 20.5 ± 0.4 Jy at the 2007 epoch, consistent with a factor of ∼2 increase since the 1960s.
Full Text:
Date Issued: 2020

Quick View

Occurrence of early stage fishes associated with Anaulus australis in a temperate South African surf zone, with notes on feeding ecology and incidental microplastic consumption in a dominant species

- McGregor, Steven

Authors: McGregor, Steven
Date: 2020
Subjects: Estuarine fishes -- Ecology
Language: English
Type: Thesis , Masters , MSc
Identifier: http://hdl.handle.net/10948/48489 , vital:40881
Description: Surf zones are important fish nursery areas, however, microhabitats and threats to fishes within them remain understudied. Diatom accumulations in surf zones are a worldwide phenomenon on certain beach types and discolour the water, offering refuge from visual predators and feeding opportunities for fishes, thus providing a microhabitat for early stage fishes. Surf diatom accumulations require long lasting rip current-entrained gyres to occur, which also entrap buoyant microplastics. These microplastics may then be consumed by filter feeding fishes such as the Southern mullet Chelon richardsonii. This work aimed to assess the extent of association of early stage fishes with diatom Anaulus australis accumulations and the feeding ecology and incidence of microplastic ingestion in the commercially important and dominant surf zone mugilid C. richardsonii. Early stage fishes were sampled within and outside of A. australis accumulations in the Sundays Beach surf zone on the southeast coast of South Africa, using a 4.5 x 1.5 m modified larval seine net with 500 µm mesh. Later developmental stage C. richardsonii were captured using a cast net. A total of 338 replicate larval fish seine hauls were done, capturing 1074 fishes including 33 taxa from 19 families. To assess ontogenetic shifts in diet of the dominant species C. richardsonii, stomach contents of 150 fish were categorised and assessed by prey abundance, frequency of occurrence, volume, index of relative importance and dietary niche breadth and compared across all developmental stages, excluding flexion and preflexion. Dominant families of early stage fishes were Sparidae, Soleidae, Mugilidae and Clupeidae that comprised 93 % of the catch, with dominant species including Heteromycteris capensis, Rhabdosargus holubi, Solea turbynei, Diplodus capensis and Chelon richardsonii. Species diversity and catch per unit effort (CPUE) were significantly higher within accumulations compared to outside, as was the CPUE of postflexion larvae and early juveniles. Generalized Linear Models showed that temperature, dissolved oxygen (mg l-1 ), turbidity and A. australis biomass (µg Chl a l -1 ) were the most significant factors affecting the overall CPUE and that of dominant species. It was suggested that after reaching the postflexion stage of development, fishes utilise diatom accumulations opportunistically when and where they are present. A diet study of the dominant species showed an ontogenetic dietary shift in C. richardsonii using A. australis accumulations as a feeding area, with postflexion larvae feeding mostly on copepods and microplastic fibres, while later developmental stages consumed predominantly A. australis cells and sand. Microplastic fibres were present in 40 % of fish sampled and microplastic fragments in 5 %, with both types found in all developmental stages assessed. It was suggested that C. richardsonii were unable to distinguish microplastics from their natural prey and incidentally ingested them. This presents a conservation concern, because chemicals associated with microplastics could bioaccumulate and biomagnify up the food chain if key baitfish species such as C. richardsonii are ingesting plastic. This study was the first to assess the association of early stage fishes with surf diatom accumulations, and the first to record microplastic ingestion in C. richardsonii. Understanding the function of microhabitats for early stage fishes and threats within them is needed to understand the life history strategies and survival of fishes in key coastal nursery and feeding areas.
Full Text:
Date Issued: 2020

Quick View

Occurrence of Indo-Pacific bottlenose dolphins (Tursiops aduncus) off the Wild Coast of South Africa using photographic identification:

- Caputo, Michelle, Bouveroux, Thibaut, Froneman, P William, Shaanika, Titus, Plön, Stephanie

Authors: Caputo, Michelle , Bouveroux, Thibaut , Froneman, P William , Shaanika, Titus , Plön, Stephanie
Date: 2020
Language: English
Type: text , article
Identifier: http://hdl.handle.net/10962/160367 , vital:40439 , https://0-doi.org.wam.seals.ac.za/10.1111/mms.12740
Description: The present study represents the first reported boat‐based photographic identification study of Indo‐Pacific bottlenose dolphins (Tursiops aduncus) off the Wild Coast of southeast South Africa. This area is known for the annual sardine run, which attracts apex predators to the region during the austral winter. Dedicated photo‐identification surveys were conducted along this coast at three different study sites in February, June, and November of each year from 2014 to 2016.
Full Text:
Date Issued: 2020

Quick View

Occurrence of selected endocrine disrupting compounds in the Eastern Cape province of South Africa:

- Farounbi, Adebayo I, Ngqwala, Nosiphiwe P

Authors: Farounbi, Adebayo I , Ngqwala, Nosiphiwe P
Date: 2020
Language: English
Type: text , article
Identifier: http://hdl.handle.net/10962/148447 , vital:38740 , DOI: 10.1007/s11356-020-08082-y
Description: Endocrine-disrupting compounds are attracting attention worldwide because of their effects on living things in the environment. Ten endocrine disrupting compounds: 4-nonylphenol, 2,4-dichlorophenol, estrone, 17β-estradiol, bisphenol A, 4-tertoctylphenol, triclosan, atrazine, imidazole and 1,2,4-triazole were investigated in four rivers and wastewater treatment plants in this study. Rivers were sampled at upstream, midstream and downstream reaches, while the influent and effluent samples of wastewater were collected from treatment plants near the receiving rivers. Sample waters were freeze-dried followed by extraction of the organic content and purification by solid-phase extraction. Concentrations of the compounds in the samples were determined with ultra-high performance liquid chromatography-tandem mass spectrometry. The instrument was operated in the positive electrospray ionization (ESI) mode.
Full Text:
Date Issued: 2020

Quick View

Ocean dynamics of the shelf and bays of the eastern Agulhas bank: a process-oriented numerical modelling study

- Bailey, Dylan Francis

Authors: Bailey, Dylan Francis
Date: 2020
Subjects: Oceanography -- Research , Marine biology , Marine meteorology , Hydrography
Language: English
Type: Thesis , Doctoral , DPhil
Identifier: http://hdl.handle.net/10948/49038 , vital:41595
Description: There is a general need for a broader base of information on the finer detail of ocean processes in the Eastern Agulhas Bank region. In this thesis, the Regional Ocean Modelling System (ROMS) was applied to resolve high resolution (~1km) bay and shelf scale ocean processes along the south eastern coastline of South Africa using an offline multi-nested approach. Experimental and reference ocean model runs were used with in situ instrument mooring data to investigate how currents and temperature in the bays and the adjacent shelf are affected by the bathymetry, Agulhas Current (AC), regional winds, and coastal trapped waves (CTW). Focus was given to temperature, circulation, and coastal trapped waves, given the abundance of hourly in situ mooring data for these variables, making them suitable for comparison with the ocean model. SST variability trends were seasonally and spatially predictable, being greatest in the summer months and smallest in the winter months. A region of high SST variability extended from Port Alfred toward the south-west, indicating entrainment of nearshore upwelled water and instabilities in the inshore front of the AC. Shelf bottom temperature variability had a more spatially diverse seasonal trend, with coastal variability the highest (lowest) and offshore variability the lowest (highest) during the summer (winter) months. A distinct asymmetry in mean seasonal shelf bottom temperatures evident to the south of Algoa Bay and St Francis Bay was shown to be dependent on the profile of the shelf margin in relation to the inshore front of the AC using an experimental model run. Bay-scale anti-cyclonic circulation patterns dominate the bays throughout the year, with regions of strong mean surface currents occurring south of Cape Recife and Cape St Francis. General circulation patterns over the shelf are strongly governed by regional wind regimes, with the strongest flows being south-westward occurring during north-easterly wind events. Shelf bottom flows typically follow the expected Ekman-veering response, apart from near coastal flows that are topographically steered. A region of consistently strong south-westward shelf bottom flow extends from the east of Port Alfred to the shelf margin south of Bird Island. This flow is predominantly driven by the AC, although its velocity is strongly governed by regional winds. Circulation patterns during powerful eastward moving wind systems are strongly governed by the passage of associated CTW. Comparisons with an experimental model run where surface winds were removed revealed that the shelf wave was responsible for 61% of water volume displacement during a CTW event, and that the coastal shear turbulence caused by this displacement has a direct effect on the mixed layer depth. The links made between the complex shelf and bay ocean processes indicate that subtle changes to the ocean state will have far reaching effects on the regional ocean environment and its biota. Given the challenges of climate change, this is of paramount importance if we are to quantify these effects and mitigate their impacts, particularly with respect to the socio-economic dependency of those who rely on the ocean for its living resources.
Full Text:
Date Issued: 2020

Quick View

Older people’s perspectives on the effectiveness of eye movement integration (emi) therapy as treatment intervention for their trauma symptoms

- Visagie, Andrea

Authors: Visagie, Andrea
Date: 2020
Subjects: Post-traumatic stress disorder in old age
Language: English
Type: Thesis , Masters , MSc
Identifier: http://hdl.handle.net/10948/46389 , vital:39601
Description: Many research studies propose that we have an ageing population with an increased number of people living past the age of 85 years. Ageing is accompanied by a gradual decline in physical, mental and sensory abilities. Older people may have experienced trauma throughout their lives, and very often, their symptoms of trauma are regarded as part of the ageing process rather than actual symptoms of trauma. In addition, older people often do not seek help throughout their lives for various reasons. While there is research available about older people and trauma, little is known about Eye Movement Integration(EMI)therapy as a treatment intervention in treating symptoms of trauma in older persons. The purpose of this research was an explorative and descriptive study of older people’s responses to EMI therapy as a treatment intervention for their symptoms of trauma. More specifically, the study was designed to determine how older people process their symptoms through EMI therapy and whether they view it as valuable. This qualitative study used an exploratory-descriptive research design with a non-probability, purposive sampling method. The EMI therapy sessions were offered to older adults in the Knysna area who presented with symptoms of trauma. From this group, only those who were able and willing to engage in therapeutic interviews formed part of the research. As part of the study, they consented to the use of their inventories from the EMI sessions as a qualitative document analysis and taking part in qualitative interviews to explore their views on the usefulness of EMI therapy to deal with their trauma. The findings emphasise that older people are not familiar with EMI. However, they view their experience of it in a positive light and regard it as a useful treatment intervention for treating their symptoms. Moreover, EMI seems to be a brief and cost-effective trauma intervention with practical benefits for older adults. The results from this study can assist social work professionals, specifically those working with older people, to address and improve the overall health and emotional wellbeing of older people. Data verification methods ensured the validity of this study
Full Text:
Date Issued: 2020

Quick View

On locating the experiences of second year science students from rural areas in Higher Education in the field of science: lived rural experiences

- Madondo, Nkosinathi Emmanuel

Authors: Madondo, Nkosinathi Emmanuel
Date: 2020
Subjects: Science students -- South Africa , Rural college students -- South Africa , Science -- Study and teaching (Higher) -- South Africa , Curriculum change -- South Africa , Learning -- Evaluation , Social justice and education -- South Africa , Action research in education -- South Africa , Participant observation -- South Africa , Critical realism , Ethnoscience -- South Africa , Focus groups -- South Africa , Bernstein, Basil
Language: English
Type: Thesis , Doctoral , PhD
Identifier: http://hdl.handle.net/10962/145758 , vital:38464
Description: This study was designed to investigate the experiences of Second Year Science students who come from rural backgrounds within a Higher Education context. The purpose of the study was to understand the enabling and/or constraining factors that influence the teaching and learning of Second Year Science students who come from rural contexts. Given this purpose, the participants that were considered relevant to answer the question: What are the enabling and constraining factors that influence teaching and learning of second year Science students who come from rural backgrounds at a South African University? were students from rural areas enrolled in the Faculty of Science at the research site, academic teachers and senior leaders’, and roles in providing enabling and/or constraining teaching and learning environment. The phenomenon under investigation was thus, the extent to which the teaching and learning environment, in the field of science, enable or constrain access to the Discourse of science for students who come from rural areas. To generate data, the study used focus group discussions, Participatory Learning and Action (PLA) tools as part of Participatory Action Research (PAR), digital documentaries, as well as academic teachers’ rich descriptions of the rationale for the design and delivery techniques of their modules by means of focus group interviews, as well as curriculum review documents. The purpose of Action Research (AR) in this study was to enable change by way of advancing a self-consciousness, envisaged to yield some action based on the enablements or constraints identified by the participants involved. Archer’s (1995, 1996) analytical dualism was used as the analytical framework to identify the interplay of structural, cultural and agential mechanisms shaping the emergence of, and practices associated with students’ experiences of the science curriculum and academic teachers’ observations of these experiences. Bernstein’s pedagogic device was also used to explain the options that academic teachers have to shape the curriculum, a curriculum that would reflect the experiences of the heterogeneity of the student cohort when designing their course guides, for example. The analysis thus used Archer’s (1995, 1996) Morphogenesis/Morphostasis framework through which change or non-change can be observed over time. The work of Bhaskar (1975, 1979) was important in this regard because it allows us to separate what we see, experience and understand (in the transitive world) from what is independent of our thoughts and experiences (the intransitive world) when conducting scientific enquiry, so that we are able to deduce the ‘real’ factors that enable and constrain the events and experiences being studied. Since there are multiple mechanisms operative that can act to include or exclude students in Science classrooms, particularly those who come from lower class, including those who come from rural areas, this study focuses on curriculum as one mechanism that can be at play in the problem of exclusion. In this study, I argue, the University and its structures like curriculum are not neutral but are historical, cultural, political and social, which is why persistent apartheid legacy and coloniality were seen as playing a role in how the curriculum is designed and thus enacted. This is the reason, a decolonial gaze was adopted in order to engage with social justice issues and in the process tease out the social relations of knowledge practices. A decolonial gaze provided a way to re-describe the structuring of the curriculum and the contradictions it sets up for black students, particularly those who come from lower class backgrounds, including those from rural areas. Findings reveal that the way in which the science curriculum (and/or teaching and learning) is structured, and thus enacted, tends to favour certain worldviews to the exclusion of others. Also, findings show that when students are presented with knowledge that seems completely separate from them, their identities, their heritage, their backgrounds and value systems, accessing that knowledge can seem inordinately difficult. Consequently, students from rural contexts are often alienated, because the “world” they bring and know is often not considered part of the starting point, neither is it seen as relevant when teaching the science curriculum. There is therefore a clear need to bring something ‘from home’ into our teaching as a means of reassuring students that all is not foreign and that what they already know is valuable.
Full Text:
Date Issued: 2020

Quick View

On the move: New insights on the ecology and management of native and alien macrophytes

- Hofstra, Deborah, Schoelynck, Jonas, Ferrell, Jason, Coetzee, Julie A, de Winton, Mary, Bickel, Tobias O, Champion, Paul, Madsen, John, Bakker, Elisabeth S, Hilt, Sabine, Matheson, Fleur, Netherland, Mike, Gross, Elisabeth M

Authors: Hofstra, Deborah , Schoelynck, Jonas , Ferrell, Jason , Coetzee, Julie A , de Winton, Mary , Bickel, Tobias O , Champion, Paul , Madsen, John , Bakker, Elisabeth S , Hilt, Sabine , Matheson, Fleur , Netherland, Mike , Gross, Elisabeth M
Date: 2020
Subjects: To be catalogued
Language: English
Type: text , article
Identifier: http://hdl.handle.net/10962/419346 , vital:71636 , xlink:href=" https://doi.org/10.1016/j.aquabot.2019.103190"
Description: Globally, freshwater ecosystems are under threat. The main threats come from catchment land-use changes, altered water regimes, eutrophication, invasive species, climate change and combinations of these factors. We need scientific research to respond to these challenges by providing solutions to halt the deterioration and improve the condition of our valuable freshwaters. This requires a good understanding of aquatic ecosystems, and the nature and scale of changes occurring. Macrophytes play a fundamental role in aquatic systems. They are sensitive indicators of ecosystem health, as they are affected by run-off from agricultural, industrial or urban areas. On the other hand, alien macrophytes are increasingly invading aquatic systems all over the world. Improving our knowledge on the ecology and management of both native and alien plants is indispensable to address threats to freshwaters in order to protect and restore aquatic habitats. The International Aquatic Plants Group (IAPG) brings together scientists and practitioners based at universities, research and environmental organisations around the world. The main themes of the 15th symposium 2018 in New Zealand were biodiversity and conservation, management, invasive species, and ecosystem response and restoration. This Virtual Special Issue provides a comprehensive review from the symposium, addressing the ecology of native macrophytes, including those of conservation concern, and highly invasive alien macrophytes, and the implications of management interventions. In this editorial paper, we highlight insights and paradigms on the ecology and management of native and alien macrophytes gathered during the meeting.
Full Text:
Date Issued: 2020

Quick View

Optical diamond turning of rapidly solidified aluminium alloy grade - 431

- Oyekunle, Funsho Adekunle

Authors: Oyekunle, Funsho Adekunle
Date: 2020
Subjects: Aluminum alloys
Language: English
Type: Thesis , Masters , MEng
Identifier: http://hdl.handle.net/10948/46860 , vital:39670
Description: The high demand for ultraprecision machining systems is increasing day by day. The technology leads to increased productivity and quality manufactured products, with an excellent surface finish. Therefore, these products are in demand in many industrial fields such as space, national defence, the medical industry and other high-tech industries. Single point diamond turning (SPDT) is the core technology of ultraprecision machining, which makes use of single-point crystalline diamond as a cutting tool. This technique is used for machining an extensive selection of complex optical surfaces and other engineering products with a quality surface finish. SPDT can achieve dimensional tolerances in order of 0.01um and surface roughness in order of 1nm. SPDT is not restricted, but mostly applicable, to non-ferrous alloys; due to their reflective properties and microstructure that discourages tool wear. The focus of this study is the development of predictive optimisation models, used to analyse the influence of machining parameters (speed, feed, and depth of cut) on surface roughness. Moreover, the study aims to obtain the optimal machining parameters that would lead to minimum surface roughness during the diamond turning of Rapidly Solidified Aluminium (RSA) 431. In this study, Precitech Nanoform 250 Ultra grind machine was used to perform two experiments on RSA 431. The first machining process, experiment 1, was carried out using pressurized kerosene mist; while experiment 2 was carried out with water as the cutting fluid. In each experiment, machine parameters were varied at intervals and the surface roughness of the workpiece was measured at each variation. The measurements were taken through a contact method using Taylor Hobson PGI Dimension XL surface Profilometer. Acoustic emission (AE) was employed as a precision sensing technique – to optimize the machining quality process and provide indications of the expected surface roughness. The results obtained revealed that better surface roughness can be generated when RSA 431 is diamond-turned using water as a cutting fluid, rather than kerosene mist. Predictive models for surface roughness were developed for each experiment, using response surface methodology (RSM) and artificial neural networks (ANN). Moreover, RSM was used for optimisation. Time domain features acquired from AE signals, together with the three cutting parameters, were used as input parameters in the ANN design. The results of the predictive models show a close relationship between the predicted values and the experimental values for surface roughness. The developed models have been compared in terms of accuracy and cost of computation - using the mean absolute percentage error (MAPE).
Full Text:
Date Issued: 2020

Quick View

Optical limiting properties of D-π-A BODIPY dyes in the presence and absence of methyl groups at the 1, 7-positions

- May, Aviwe K, Mack, John, Nyokong, Tebello

Authors: May, Aviwe K , Mack, John , Nyokong, Tebello
Date: 2020
Subjects: To be catalogued
Language: English
Type: text , article
Identifier: http://hdl.handle.net/10962/186146 , vital:44468 , xlink:href="https://doi.org/10.1142/S1088424620500315"
Description: The optical limiting properties of three meso-pentafluorophenylstyrylBODIPY dyes are investigated in the presence and absence of methyl groups at the 1,7-positions that hinder free rotation of the meso-aryl group. Pentafluorophenyl groups are introduced at the meso-position, while 4-diethylaminostyryl groups are introduced at the 3- and/or 5-positions to form dyes with strong donor-ππ-acceptor (D-ππ-A) properties to enhance the dipole moment of the molecule. Favorable optical limiting properties are obtained for all three dyes, with the highest second-order hyperpolarizability value obtained for a monostyryl dye with no methyl groups at the 1,7-position. Bromination at the 2,6-positions of a 1,7-methyl substituted dye is found to result in second-order hyperpolarizability that is an order of magnitude lower than that calculated for the analogous non-halogenated dye.
Full Text:
Date Issued: 2020

Quick View

Optical limiting properties of indium 5, 10, 15, 20-tetrakis (4-aminophenyl) porphyrin covalently linked to semiconductor quantum dots

- Managa, Muthumuni, Mgidlana, Sithi, Khene, Samson M, Nyokong, Tebello

Authors: Managa, Muthumuni , Mgidlana, Sithi , Khene, Samson M , Nyokong, Tebello
Date: 2020
Subjects: To be catalogued
Language: English
Type: text , article
Identifier: http://hdl.handle.net/10962/186101 , vital:44463 , xlink:href="https://doi.org/10.1016/j.ica.2020.119838"
Description: 5,10,15,20-tetrakis(4-aminophenyl) porphyrin and it indium derivative were synthesised and characterized then covalently linked to CdTe/ZnSe/ZnO semiconductor quantum dots. The nonlinear absorption of the complexes was studied using the Z-scan technique at 532 nm and 10 ns pulse in dimethyl sulfoxide. Indium 5,10,15,20- tetrakis(4-aminophenyl) porphyrin (InTAPP) exhibited the strongest nonlinear optical behaviour in comparison with the metal free derivative. DFT calculations were carried out using SDD basis set at B3LYP level of theory. The nonlinear absorption coefficient (βeff) values were determined experimentally using Z-scan whereby the first static hyperpolarizability (βHRS) value were determined using DFT calcutions.
Full Text:
Date Issued: 2020

Quick View

Optical limiting properties, structure and simplified TD-DFT calculations of scandium tetra-15-crown-5 phthalocyaninates:

- May, Aviwe K, Majumdar, Poulomi, Martynov, Alexander G, Lapkina, Lyudmila A, Troyanov, Sergey I, Gorbunova, Yulia G, Tsivadze, Aslan Yu, Mack, John, Nyokong, Tebello

Authors: May, Aviwe K , Majumdar, Poulomi , Martynov, Alexander G , Lapkina, Lyudmila A , Troyanov, Sergey I , Gorbunova, Yulia G , Tsivadze, Aslan Yu , Mack, John , Nyokong, Tebello
Date: 2020
Language: English
Type: text , article
Identifier: http://hdl.handle.net/10962/163553 , vital:41048 , https://0-doi.org.wam.seals.ac.za/10.1142/S108842462050011X
Description: The optical limiting properties of crown-ether-substituted scandium(III) phthalocyaninate complexes, bis-tetra-15-crown-5-phthalocyaninates Sc[(15C5)4Pc]∙022•0 (I) and Sc[(15C5)4Pc]−22− (Ia), together with monophthalocyaninate [(15C5)4Pc]Sc(OAc) (II) were measured by using the Z-scan technique (532 nm laser and pulse rate of 10 ns).
Full Text:
Date Issued: 2020

Quick View

Optically stimulated luminescence and spectral emission features of radioluminescence and thermoluminescence of natural kunzite:

- Alatishe, M A, Ogundare, F O, Folley, Damilola E, Chithambo, Makaiko L, Chikwembani, S

Authors: Alatishe, M A , Ogundare, F O , Folley, Damilola E , Chithambo, Makaiko L , Chikwembani, S
Date: 2020
Language: English
Type: text , article
Identifier: http://hdl.handle.net/10962/160478 , vital:40449 , https://doi.org/10.1016/j.radmeas.2020.106457
Description: Features of luminescence optically stimulated from natural kunzite using 470 nm blue light are reported. Preparatory measurements of its X-ray excited radioluminescence and thermoluminescence show that the sample has two main bands centered at 360 nm and 600 nm. The optically stimulated luminescence discussed in this report was monitored in the UV region and is presumed to be the same 360 nm emission that appears in the radioluminescence and thermoluminescence spectra. The glow curve shows at least three peaks at 74, 202, 432 oC for heating at 1 oC and the third one is a composite of two. Only the first two peaks are deduced to contribute most of the optically stimulated luminescence.
Full Text:
Date Issued: 2020

Quick View

Oral Phytothymol ameliorates the stress induced IBS symptoms

- Subramaniyam, Selvaraj, Yang, Shuyou, Diallo, Bakary N, Fanshu, Xu, Lei, Luo, Li, Chong, Tastan-Bishop, Özlem, Bhattacharyya, Sanjib

Authors: Subramaniyam, Selvaraj , Yang, Shuyou , Diallo, Bakary N , Fanshu, Xu , Lei, Luo , Li, Chong , Tastan-Bishop, Özlem , Bhattacharyya, Sanjib
Date: 2020
Subjects: To be catalogued
Language: English
Type: text , article
Identifier: http://hdl.handle.net/10962/426034 , vital:72308 , xlink:href="https://doi.org/10.1038/s41598-020-70420-4"
Description: Physical stressors play a crucial role in the progression of irritable bowel syndrome (IBS). Here we report a heterogeneous physical stress induced IBS rat model which shows depression and subsequent modulation of IBS by oral treatment of thymol. Oral administration of Thymol reduces the stress induced IBS significantly altering the stress induced gastrointestinal hypermotility, prolonged the whole gut transit time, and increased abdominal withdrawal reflex suggesting gastrointestinal hypermotility and visceral discomfort caused the onset of depression. Immunohistochemical analysis in small intestine and colon of rats shows the decreased 5-HT3AR expression level while thymol treatment normalized the 5-HT3AR expression in the stressed rats. Molecular docking studies showed that thymol competes with endogenous serotonin and an antagonist, Tropisetron and all have similar binding energies to 5-HT3AR. Molecular dynamics simulations revealed that thymol and tropisetron might have similar effects on 5-HT3AR. Our study suggest that thymol improves IBS symptoms through 5-HT3AR, could be useful for the treatment of IBS.
Full Text:
Date Issued: 2020

Quick View

Orchid mycorrhizal and endophytic fungal diversity of three co-occurring terrestrial orchids in the large African genus Disa (Orchidaceae)

- Khambule, Nondumiso Venessia

Authors: Khambule, Nondumiso Venessia
Date: 2020
Subjects: Orchids South Africa , Mycorrhizal fungi South Africa , Endomycorrhizas South Africa , Endophytes , Orchids Roots
Language: English
Type: Doctoral theses , text
Identifier: http://hdl.handle.net/10962/163341 , vital:41030
Description: Orchids (in the family Orchidaceous) are one of the richest plant families and approximately 500 species are found in South Africa. A number of orchid species are found on disturbed areas and many of the terrestrial species grow in poor soils with low mineral nutrient availability. Most orchid species are thought to be associated with mycorrhizal fungi for germination and mycorrhiza provides nutrients for the survival of adult plants. The aim of this study was to select Orchidaceous plant species and to isolate, identify and characterize the orchid endophytes and assess these isolates for potential antimicrobial and enzymatic activities Isa is the largest genus in South Africa and three Disa species co-occurring in a small geographical area were selected. These included Disa bracteata, D. cornuta and D. polygonoides which span three sections of the genus. Roots were stained to confirm the mycorrhizal status of the Disa species. Mycorrhizal pelotons structures were microscopically observed inside root cells. The presence of pelotons is indictive of mycorrhizal fungal interactions within the orchid roots and areas associated with the site of nutrient exchange between plant and fungus. The presence of pelotons, however, does not give n indication of the fungal species involved. The endophytes were successfully isolated in pure cultures on potato dextrose agar (PDA). All slow growing isolates were selected, and further molecular identification undertaken; DNA was extracted, and PCR amplified using internal transcribed spacer (ITS1F and ITS4) fungal primers. The amplified products were then sequenced and analysed by comparison to sequences in the GenBank database. Trichoderma, Penicillium, Metapochonia, Talaromyces, Oidiodendron Neopestalotiopsis, and Chaetomium were identified from these sequences. The presence of other fungal root endophytes was suspected despite the rigorous surface sterilization procedure used. The primers used to amplify the ITS region are the universal barcoding primers which are specific to fungi. ITS1F is one of the primers designed to amplify a broad range of fungi. DNA was extracted from orchid roots and amplicons were cloned into a pGEMT plasmid vector. Individual clones were sequenced and aligned with Mega software and compared to sequences in the GenBank and UNITE database. Based on percentage sequence identity, unidentified Tulasnella species, Tullasnela colaspora, and various Ascomycota endophytes were identified as contributing to the endophytic root fungal diversity of the selected Disa species. The Disa species investigated in this study were associated with several soil endophytes. D. bracteata, D. polygonoides were collected from the same site along the road verge which is regarded as being disturbed. Based on both culture – dependent and independent techniques employed Oidiodendron was found associated with both species. Antimicrobial activity was determined using a well diffusion method using extracts from the isolated fungi against the bacterial isolates Bacillus cereus, Staphylococcus aureus, Escherichia coli and Pseudomonas puptida. Most of the isolated fungi showed at least one potential inhibition effect against one of the bacterial isolates. The extracts that showed potential antimicrobial activity could be further screened to determine the compounds produced as secondary metabolites using techniques such as LC-MS Enzymatic activities of protease, cellulose and amylase were determined using solid media amended with milk protein, carboxymethylcellulose (CMC) and starch. The majority of fungal isolates tested positive with amylase and cellulose with only a few fungal isolates testing positive for protease activity. Broth cultures containing CMC and starch were shown to enhance biomass production in approximately 40 % of the fungal isolates. Degradation of the substrates is required in order to provide carbon to the fungus under test in order to optimize fungal growth as well as to gain insight into their ecological role. Enzyme activity was evident particularly when cellulose and starch were provided as substrates. All the fungal isolates tested grew on the amended medium, with 40% of the isolates preferring to utilize CMC and/or starch, indicating the ability of these fungi to utilize various resources for carbon acquisitions. , Thesis (PhD) -- Faculty of Science, Biochemistry and Microbiology, 2020
Full Text:
Date Issued: 2020

Quick View

Organisational influences and the effects on female advancement within a South African technology organisation

- Hare, Claire Kim

Authors: Hare, Claire Kim
Date: 2020
Subjects: Women in technology -- South Africa -- Eastern Cape.
Language: English
Type: Thesis , Masters , MBA
Identifier: http://hdl.handle.net/10948/48136 , vital:40503
Description: The underrepresentation of females within various sectors, specifically the technology industry, remains a concern. Even though there is progression regarding the representation of women in the technology industry, females and other diverse groups are still underrepresented within the IT workforce. Globally, women make up only 25% of technology workers and only 23% of technology workers in South Africa are female. The underrepresentation of women in technology jobs results in the industry lacking an immense amount of brainpower and the potential for innovation. Against this background, the primary objective of this study was to identify the impact that the organisational influences i.e. leadership, organisational culture, barriers and organisational change management has on the advancement of females within a technology organisation. This study was conducted within a South African technology organisation located within the Eastern Cape region. A quantitative approach was adopted, and purposive sampling was used to draw the sample of approximately three hundred personnel, including all managers and employees, within the South African technology organisation for this study. Various findings emerged in terms of the research questions about whether the organisational influences of leadership, organisational culture, barriers and organisational change management has an impact on the advancement of females within the technology organisation. The empirical results revealed that leadership and organisational change management have the strongest positive influence on the advancement of females within the organisation. A key finding within this study is that leadership within the organisation does not promote female advancement. Since literature suggests that leadership is instrumental in shaping the organisational culture of an organisation, the focus of the organisation should be on equipping leadership with the knowledge and skills to influence the rest of the organisation regarding gender equality. An additional recommendation is that the women who currently occupy leadership positions within the organisation could mentor other females to overcome or cope with prejudice and gender experienced.
Full Text:
Date Issued: 2020

Quick View

Organisational justice as a predictor of organisational citizenship behaviour among academic employees at the University of Fort Hare in South Africa

- Matsungo, Forget

Authors: Matsungo, Forget
Date: 2020
Subjects: Organizational change Universities and colleges -- South Africa -- Eastern Cape
Language: English
Type: Thesis , Masters , MCom (Industrial Psychology)
Identifier: http://hdl.handle.net/10353/12458 , vital:39265
Description: This research was designed to examine the relationship between Organisational Justice (OJ) constructs and Organizational Citizenship Behaviour (OCB). This study was based on social exchange theory, the norm of reciprocity. The sample for the study consisted of 184 academic members of staff from the University of Fort Hare in the Eastern Cape Province, South Africa. Moorman and Niehoff (1993). Organizational Justice Scale was used to measure justice and Podsakoff, MacKenzie, Moorman, and Fetter’s (1990) OCB Scale was used to measure extra role behaviours. Data analysis was done by means of the Spearman Rank Order Correlation Coefficient and Multiple Regression Model using the Statistical Package for Social Sciences (SPSS) version 25. The findings revealed a positive and significant relationship between OJ and OCB. More specifically, OJ was revealed be significantly positively associated with the measures of OCB (courtesy, altruism, civic virtue, conscientiousness, and sportsmanship) at the University of Fort Hare. Therefore, to improve work performance it is imperative that the university should continuously ensure and promote: fairness in their decisions relating (distributive justice); fairness of the methods, mechanisms, processes, and procedures used to determine the decisions or outcomes (procedural justice); as well as fairness in the quality of the interpersonal treatment employees receive within the work environment (interactional justice). This is particularly so, because when employees perceives that there is emphasis on justice or fairness (procedural justice, distributive justice, and interactional justice) within the organisation, they may reciprocate this gesture by displaying desirable discretionary work related behaviours. Theoretical and managerial implications and suggestions for future research are discussed
Full Text:
Date Issued: 2020

Quick View

Parents’ perceptions of the content of pre-school lunch boxes following a nutritional programme in Nelson Mandela Bay

- Midigo, Odwour Erich

Authors: Midigo, Odwour Erich
Date: 2020
Subjects: Children -- Nutrition
Language: English
Type: Thesis , Masters , MSc
Identifier: http://hdl.handle.net/10948/46429 , vital:39587
Description: Rationale: Lunchboxes that parents prepare for preschool children have been noted to fall short of the recommended paediatrics dietary standards. No research has been done in Nelson Mandela Bay (NMB) to describe the perceptions of parents preparing the lunch boxes, particularly in underprivileged communities, and if nutrition education strategies can improve these practices. This study answered the following research question: How can nutrition education programmes play a role in parents’ perceptions about the content of the lunchboxes of children attending early childhood development centres (ECD) in underprivileged communities of NMB metropole? Aim: The research aimed at describing and exploring parents’ perceptions of the content of pre-school children’s lunch boxes following a nutrition programme.Methods: This descriptive, explorative study adopted a qualitative approach. Twenty-five participants were selected conveniently while five pre-schools were purposively sampled. Following the nutrition programme, data was collected through five Focus Group (FG) discussions and five interviews and was thematically analysed. The ethical principles that guided the study included justice, beneficence and autonomy. Results and Discussion: Five major themes and seventeen sub-themes emerged (1) Participants described the typical foodstuff in children’s lunch boxes which included both high quality and lower-quality foods and fluids; (2) Participants provided views (such as food preferences) on lunch box choices; (3) Principals appraised lunch box rules and the significance of revised rules to improve the lunch boxes;(4) Challenges such as poverty limited healthy food choices; (5) Participants commented on initiatives noted following the nutrition training; for instance, some schools commenced the cultivation of vegetable gardens. Conclusion and Recommendations: The study highlights that specific parent programmes helped to improve healthy lunch box choices in the study population. There is a need for parent programmes tailored to fathers. Dieticians and nutritionists in NMB can train practitioners as change agents in their respective schools.
Full Text:
Date Issued: 2020

Showing items 4501 - 4520 of 29951