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Investigate how ethical organisational behaviour in service delivery at the Gqeberha labour centre can be improved

  • Authors: Khahlana, Lwazi
  • Date: 2024-12
  • Subjects: Corporate culture , Business ethics , Psychology, Industrial
  • Language: English
  • Type: Master's theses , text
  • Identifier: http://hdl.handle.net/10948/70231 , vital:78331
  • Description: The public service is often perceived and experienced as not meeting the expectations of the public. The Gqeberha Labour Centre (GQE LC) is not exempted to prevalence of unethical work behaviours in service delivery. The GQE LC is the Department of Employment and Labour (DEL) branch. The purpose of the study is to investigate how ethical organisational behaviour in service delivery at GQE LC can be improved. The study applied qualitative approach through an interpretivism paradigm. The study used purposive sampling strategy. The sample size had ten participants, seven professionals and three management. The data was collected making use of semi-structured interviews that were done one-on-one. A Computer-Assisted Qualitative Data Analysis Software was used to transcribe the data. The data analysis was done manually using thematic analysis. The findings on leadership role in the improvement of ethical organisational behaviour, indicated training is one of the key roles to be implemented by leadership; leadership should be exemplary on ethical organisational behaviour; new employees should be onboarded on ethical organisational behaviour as soon as they are employed. The finding improvement and mitigation of causes and negative outcomes of unethical behaviour, indicated whistleblowing should be encouraged; unethical behaviour be sanctioned and continuous training on ethical organisational behaviour. , Thesis (MBA) -- Faculty of Business and Economic Sciences, Business School, 2024
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  • Date Issued: 2024-12

Investigating the implementation of teaching strategies used by foundation phase teachers in multilingual classrooms

  • Authors: Green, Marizanne
  • Date: 2024-12
  • Subjects: Multiculturalism -- Study and teaching , Language and languages -- Study and teaching , Education, Bilingual -- South Africa
  • Language: English
  • Type: Master's theses , text
  • Identifier: http://hdl.handle.net/10948/68322 , vital:76974
  • Description: In South Africa, there are eleven official languages: English and Afrikaans and nine indigenous languages. However, the dominant language of learning and teaching in multilingual classrooms is English. Teachers are not all equipped to cater for a multilingual classroom that is conducive to learning. Hence, it is important that teaching strategies teachers used need to support learners’ access to knowledge and their language proficiency through the learning process. This qualitative case study aimed at investigating the teaching strategies used by Foundation Phase teachers in multilingual classrooms. The study was guided by an interpretivist paradigm which was helpful in providing in-depth knowledge on multilingual Foundation Phase classrooms and the teaching strategies that teachers implement. The study used a purposive sampling strategy with 4 Foundation phase teachers teaching Grades R-4. Drawing upon classroom observations and semi-structured individual interviews as the primary methods of data collection, the study explored the teaching strategies teachers use in multilingual foundation phase classrooms. A thematic data analysis was employed. Findings revealed a need for inclusive practices in FP multilingual classrooms, need to support learning using various teaching strategies, need to recognize realities in multilingual classrooms and a role that stakeholders can play in learning. Recommendations are provided for SGB’s, Curriculum designers, FP teachers and parents. , Thesis (MEd) -- Faculty of Education, School of Primary School Education, 2024
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  • Date Issued: 2024-12

Investigating the purported medicinal properties of cannabinoid containing products available for human consumption in South Africa

  • Authors: Stark, Nicole Jade
  • Date: 2024-12
  • Subjects: Thin layer chromatography , Tetrahydrocannabinol , Cannabinoids
  • Language: English
  • Type: Master's theses , text
  • Identifier: http://hdl.handle.net/10948/69716 , vital:78013
  • Description: Cannabis has until recently, in some countries, been classified as an illicit, illegal drug. In South Africa, the sale of marijuana (Cannabis sativa) is still illegal, but there has been an amendment of legislation in the governing of the use of marijuana in that the private use of marijuana was decriminalised in September 2018. This has led to questions about whether the recreational use of Cannabis should be legalised and what is the potential social implications of this legislation moving forward (Mokwena, 2019). This study aimed to assess whether the indications and consequently the concentrations associated with the declared purported use of cannabinoid containing products correspond with the information declared on the label and conform to the regulatory limits set out for these products. The objectives of this study were to explore: the range of products available in South Africa, the prescribed use and dosage of the product and to test the accuracy of the reported information on the product labelling regarding the cannabinoid content. This investigation pursued a quantitative approach that is empirical and comprised of laboratory-based experiments. A minimum of seven samples of different liquid preparations of products, reported to contain cannabinoids and being sold without the need for a prescription or licence were tested with the aid of Thin Layer Chromatography (TLC), to separate individual compounds from the many that could be found in these Cannabis products. The results of this testing of cannabidiol (CBD) and tetrahydrocannabinol (THC) and, where applicable, their concentrations were determined. Using the data collected and review of available literature, assessments were made as to whether the products tested conform to the regulatory standards and contained the cannabinoids as stated on the labelling. From the data obtained findings were that not all products currently available on the South African market correspond to the information reported on the label or conform to the regulatory standards. , Thesis (MPharm) -- Faculty of Health Sciences, School of Clinical Care & Medicinal Sciences, 2024
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  • Date Issued: 2024-12

Investigation of potential in-situ polymerization reactions for use in lithium-ion batteries

  • Authors: Dube, Tafara
  • Date: 2024-12
  • Subjects: Lithium ion batteries , Lithium cells , Electrochemistry
  • Language: English
  • Type: Master's theses , text
  • Identifier: http://hdl.handle.net/10948/68851 , vital:77127
  • Description: With the rise in popularity of electric vehicles and portable electronic devices, having a reliable, lightweight, and long-lasting battery is crucial. This has led to the mass commercialisation of lithium-ion batteries (LIB’s) because they offer several advantages over other battery technologies. Over the years, one of the concerns was with the ease with which the batteries can burn or explode when subjected to certain extreme conditions. In order to build trust in these products and to expand the technology into more diverse applications, safety aspects of the batteries has become of widespread concern resulting in a key area of research. One aspect of improving the safety is by reducing the flammability of the battery by the addition of certain chemicals that stop or suppress the thermal runaway effect. However, this in-turn reduces the battery’s capacity and life-cycle performance. Researchers have used the idea of encapsulating these chemicals thereby physically separating them within the lithium-ion battery (LIB) electrolyte system with a minimum effect on performance. This research aims to explore use of R-diols and R-amines as additives that upon a thermal trigger would react with the lithium-ion battery electrolyte to stop the effect of the thermal runaway by forming carbamate derivatives which are gel-like or form solid aggregates. The R-diols or R-amines can react with electrolyte at higher temperatures with the lithium-hexafluorophosphate acting as a catalyst. This change in the physical state of the electrolyte increases the resistance inside the battery which then hinders ion movement and forms a physical barrier to reduce the effect of short circuiting when the separator or other components are damaged due to higher temperatures. , Thesis (MSc) -- Faculty of Science, School of Biomolecular & Chemical Sciences, 2024
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  • Date Issued: 2024-12

ISO 9001 certification as a catalyst for enhancing product quality at a manufacturing plant in Gqeberha

  • Authors: Runesu, Mashoko
  • Date: 2024-12
  • Subjects: ISO 9001 Standard , Quality control -- Standards , Quality of products
  • Language: English
  • Type: Master's theses , text
  • Identifier: http://hdl.handle.net/10948/69925 , vital:78243
  • Description: This research explores the role of ISO 9001 certification as a catalyst for enhancing product quality at a manufacturing plant in Gqeberha. ISO 9001, an internationally recognised standard for quality management systems, provides a framework for consistent product quality and continuous improvement. While prior studies have shown that ISO 9001 certification creates a signalling effect, attracting customers by projecting an image of high product quality, the impact of this certification on actual product quality remains unclear. This study addresses this gap by investigating the variables necessary to enhance product quality through ISO 9001 implementation in a manufacturing context. The research seeks to answer the question: What variables should be incorporated in the implementation of ISO 9001 certification to improve product quality in a manufacturing company in Gqeberha? Specifically, the study focuses on the influence of four ISO 9001 principles, namely customer focus, leadership, engagement of people, and improvement, on product quality. A pragmatic research philosophy was adopted, utilising a quantitative approach to better understand the relationship between these principles and product quality. Both literature review and empirical results confirm that all four principles significantly impact product quality with a unit change in any of these principles or variables resulting in a 0,550-to-0,721-unit changes in product quality. Based on these results, the study recommends that companies accredited to ISO 9001 standard should integrate these principles into their daily operations. If the ISO 9001 standard is implemented with emphasis on following these guiding principles, a company will not only achieve and sustain improvements in product quality, but this can be a valuable strategic tool for competitiveness in the global marketplace. , Thesis (MBA) -- Faculty of Business and Economic Sciences, Business School, 2024
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  • Date Issued: 2024-12

Low-income area electrification systems

  • Authors: Tshabeni, Thulisa
  • Date: 2024-12
  • Subjects: Rural electrification -- Economic aspects -- South Africa , Rural electrification -- South Africa , Remote area power supply systems -- South Africa
  • Language: English
  • Type: Master's theses , text
  • Identifier: http://hdl.handle.net/10948/68807 , vital:77115
  • Description: This research investigated electrification systems for low-income, informal settlement areas via grid extension, photovoltaic mini-grids and solar home system (SHS). Six electrification systems were analysed; four mini-grid systems, a 100 W solar home system and a grid extension. All have different maximum power capacities and differ in the way they contribute to sustainable development. Affordability for the consumer of the total energy required (electrical and other sources) is a key factor for the sustainability of any electrification system. Two battery technologies, lithium-ion and lead acid batteries were compared for each system based on technical and economic performance. The study determined that despite the intial very high cost, lithium-ion batteries can achieve a lower levelized cost of electricity (LCOE) due to their long life span. It was found that the batteries cost between 58% and 95% of the project’s capital cost. The battery cost occurs not only in the capital cost, but in the replacement cost. This cost is so high, that it makes all the solar systems uneconomic. This research found that extending the national power grid is still much more economically viable than all other PV electrification systems, but it requires land tenure. The issue of land tenure could be solved by making some agreement with the land owner for rental. It was found that the PV systems could only be economic if they increased the income of the communities substantially. , Thesis (MEg) -- Faculty of Engineering, the Built Environment, and Technology, School of Engineering, 2024
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  • Date Issued: 2024-12

Portfolio effect and bet-hedging adaptations in sea turtles

  • Authors: Hoekstra, Shaun
  • Date: 2024-12
  • Subjects: Wildlife conservation , Sea turtles -- South Africa , Animal behavior
  • Language: English
  • Type: Master's theses , text
  • Identifier: http://hdl.handle.net/10948/68873 , vital:77153
  • Description: A great proportion of marine species are at risk of going extinct as a result of profound changes in the world’s oceans, primarily driven by human activities. Sea turtles are not exempt from this fate. Despite sea turtles being exposed to a range of environmental conditions and threats that vary in frequency and intensity, these ancient marine reptiles have persisted for millennia. In the past, sea turtles have been able to adapt to natural perturbations while other animal groups have not. The ability of sea turtles to adapt to contemporary changes in conditions, produced by human activities, has become limited. The persistence of sea turtles may be explained by the application of a concept termed “portfolio effect”. An aggregate system is more stable and less prone to fluctuations over time (i.e. portfolio effect) if a diversity of finer components comprises the entire system and displays asynchronous fluctuations over time. Biological entities (e.g. species measured by the abundance trend) may achieve long-term stability even though the individual components (e.g. populations measured in abundance trend) display weak or negative correlations with each other in space and time. Different sea turtle populations may display independent trends in abundances over time, resulting in a portfolio effect at species levels. Trends in sea turtle abundances may be affected by individual behaviour. The adoption of bet-hedging adaptations may enable populations to thrive despite environmental changes or stochasticity, by lowering short-term fitness in exchange for maximising long-term fitness. Individual sea turtles may exhibit bet-hedging adaptations through changes in their temporal nesting behaviour, including the remigration interval. Since remigration interval length regulates the number of nesting females per nesting season, changes in remigration interval will affect abundance trends. The ability of individuals to change their remigration interval allows them to “skip” the breeding migration when environmental conditions seem unfavourable. The overall aim of this thesis was to investigate potential reasons for observed sea turtle abundance trends at species, population, and rookery levels. I tested whether the portfolio effect applies to sea turtles by analysing and interpreting spatiotemporal trends in loggerhead (Caretta caretta) and leatherback (Dermochelys coriacea) abundances at the population and species levels using global datasets. The application of bet-hedging strategies was tested at a local level using data from the long-term monitoring program for South African nesting sea turtles. The majority of loggerhead rookeries displayed an increase in abundance over time, while most leatherback rookeries declined (Chapter 2). Population growth rates also differed among rookeries within Regional Management Units (RMUs) (Chapter 2). This diversity in abundance trends among rookeries suggested spatiotemporal variation in environmental conditions, threats and/or level of protection accompanying sea turtles. The species-level growth rate for both species displayed an overall increase in abundance over time. However, larger (more turtles) leatherback rookeries/RMUs experienced more rapid declines in abundance compared to smaller rookeries/RMUs, resulting in a recent species-level decline. Uncorrelated trends in abundances at the RMU-level could have stabilised species-level trends. Differences in the remigration intervals as a possible bet-hedging adaptation could potentially explain differences in population recovery rates between South Africa’s loggerhead and leatherback sea turtles (Chapter 3), but found no evidence that individuals from either species exhibit bet-hedging adaptations. Loggerheads, however, have increased their remigration intervals over time, while leatherbacks have not. These increases were accompanied by declines in adult body size (previously established) which could be an effect of diminishing foraging area quality. The increased remigration interval shown by loggerheads may be a response rather than an adaptation to the prevailing environmental conditions that impact their food supply in their foraging areas. The population growth rate of leatherback sea turtles may surpass that of the loggerheads in the near future, although there is a global decline in abundance (Chapter 2). This dissertation provides information on possible reasons for observed trends in sea turtle abundances at various levels of biological organisation. While a variety of factors have the potential to influence trends in sea turtle abundance, the possible occurrence of portfolio effects and investigating nesting behaviour may resolve any uncertainties regarding the reasons for observed trends in abundance. , Thesis (MSc) -- Faculty of Science, School of Environmental Sciences, 2024
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  • Date Issued: 2024-12

Prevalence and correlates of sickness presenteeism among secondary school teachers in the Bukedi region of eastern Uganda

  • Authors: Majwala,Henry
  • Date: 2024-12
  • Subjects: Employees -- Mental health , Psychology, Industrial , Industrial psychiatry
  • Language: English
  • Type: Doctoral theses , text
  • Identifier: http://hdl.handle.net/10948/68355 , vital:76989
  • Description: Education is regarded as one of the main cornerstones for sustainable development, especially if the majority of the global citizenry manage to achieve it at secondary school level. The efficaciousness thereof, however, almost entirely depends on the productivity and performance of teachers meant to instill various skill sets among secondary school learners. Sickness presenteeism among secondary school teachers has previously emerged and gained attention as the single most important antagonist of secondary school productivity. However, it has been reported to be increasing in magnitude as absenteeism has gradually decreased over the years. The aim of the study was to establish the prevalence and correlates of sickness presenteeism among secondary school teachers in the Bukedi region in Eastern Uganda. The study adopted a pragmatic philosophy and a sequential explanatory mixed methods design targeting 433 secondary school teachers in the Bukedi sub region of Eastern Uganda. The schools were stratified by district first and then each district was stratified by ownership. Simple random sampling was used to sample half the number of schools per stratum, simple random sampling was used to sample the teachers. Key informants such as principals and teachers were purposively sampled and engaged in key informant semi-structured interviews. Quantitative data emerging from an analysis of the questionnaires was analyzed in SPSS version 25 using the log-binomial model, while the qualitative data from the semi-structured interviews was analyzed thematically. This study disclosed that the majority (68.3%) of the teachers engaged in sickness presenteeism. Moon lighting, egocentrism and heavy workload were the significant intrapersonal correlates of sickness presenteeism, while under staffing was a prominent institutional correlate. This study confirms findings from global research that staff working in people-based service sectors are most likely to engage in sickness presenteeism. The recommendations include the following: MoES to formulate a comprehensive policy on sickness presenteeism for teachers, DEOs to make follow ups to address the prevalent sickness presenteeism among secondary school teachers, the school administration to set up a special committee dealing with teachers’ welfare regarding ill health and work, and teachers are to be educated, sensitized about the dangers associated with sickness presenteeism and how to handle it with the school administration. , Thesis (DPhil) -- Faculty of Education, School of Post Schooling, 2024
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  • Date Issued: 2024-12

Researching the leader-member exchange model as an instrument to explore followership and leadership at the ELIDZ

  • Authors: Ralarala,Sibusiso Mzimasi
  • Date: 2024-12
  • Subjects: Leadership -- South Africa , Followership -- Social aspects , Executives
  • Language: English
  • Type: Master's theses , text
  • Identifier: http://hdl.handle.net/10948/69947 , vital:78249
  • Description: While there has been extensive research on leadership, the connection between followership and leadership is not well explored. In this relationship, the Leader–Member Exchange (LMX) model stands out as a useful framework, shedding light on the complex relationship between leaders and followers, and the ways in which their interactions influence organisational results. This research examined the LMX model in the context of the East London Industrial Development Zone (ELIDZ), in order to understand the interdependence of leaders and followers, and the effects of this relationship on the functioning of the ELIDZ. Making use of a qualitative research approach, the researcher conducted interviews and examined annual reports from the ELIDZ in order to understand the extent to which the LMX model had been applied, and the effects of this application on workplace metrics such as job satisfaction, organisational commitment and overall performance. By examining the dual nature of the leader–follower relationship, the researcher sought to bridge an existing research gap and shed light on the reciprocal influence these roles exert on the industrial development landscape. The findings of this study contribute to the existing knowledge base on leadership, and also reveal the contextual nuances that shape leader–member exchanges within the ELIDZ. The insights yielded by this study could drive meaningful enhancements in leadership strategies and development initiatives, fostering a more productive and harmonious organisational environment. The research offers actionable recommendations that, if followed, could fortify leader–follower relationships in a diversity of modern organisational settings. , Thesis (MBA) -- Faculty of Business and Economic Sciences, Business School, 2024
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  • Date Issued: 2024-12

Screening drug candidates for sars-cov-2 spike protein variants within the SANCDB (South African Natural Compounds Database) and drug bank

  • Authors: van der Merwe, Vicky
  • Date: 2024-12
  • Subjects: COVID-19 (Disease) , Vaccines -- Development , Viral vaccines
  • Language: English
  • Type: Master's theses , text
  • Identifier: http://hdl.handle.net/10948/69499 , vital:77263
  • Description: The WHO declared the Coronavirus Infectious Disease 2019 (COVID-19) pandemic as over on the 5th of May 2023. However, the Severe Acute Respiratory Syndrome Coronavirus 2 Virus (SARS-CoV-2) is still prevalently spread within populations, causing hospitalization and death in serious infections. Most anti-COVID-19 agents are weakly or conditionally or even strongly recommended against in non-severe cases with low to medium risk of hospitalisation and further highlight the significance of effective treatments for SARS-CoV-2 infected patients. The host’s Angiotensin-Converting Enzyme 2 (ACE2) interaction with the viral spike protein’s Receptor-Binding Domain (RBD) of SARS-CoV-2 leads to the subsequent infection, viral replication, and further propagation of the virus. This establishes the spike protein’s RBD as a vital target for drug design. Through HADDOCK and AlphaFold driven structural refinement, the then novel SARS-CoV-2 delta [3.34 Å (PDB ID: 7WBQ)] and omicron [3.00 Å (PDB ID: 7WBP)] crystalline structures of the variants’ RBD, in complex with its host receptor human ACE2, were modelled to improve the low-resolution starting structures. Models predicted by HADDOCK independently yielded refined structures with improved resolutions of 2.49 Å (delta) and 2.41 Å (omicron). SARS-CoV-2 spike protein RBD of delta and omicron variants were screened for less frequently considered allosteric binding sites that could block ACE2-RBD engagement. Eight potential allosteric binding sites were identified through CavityPlus for both variants, with a single best druggable potential allosteric site identified for each. The search for potential inhibiting hit compounds involved using the SANCDB and DrugBank databanks and screening both the allosteric and orthosteric binding sites through molecular docking. Despite differences in mutated interacting residues and bond interactions, a lead compound for orthosteric binding sites (SANC00290) and potential allosteric modulators of both delta and omicron (SANC00746 and DB01029) were found. These compounds show promise in blocking ACE2-RBD engagement to potentially reduce viral interaction and infection of, and potentially withstanding further mutational residues. This study contributes to further investigation of affordable SA natural compound COVID-19 treatment and a starting point for in vitro analysis studies. , Thesis (MSc) -- Faculty of Science, School of Biomolecular & Chemical Sciences, 2024
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  • Date Issued: 2024-12

Social dynamics of spotted hyaenas (Crocuta crocuta) in fenced protected areas: Implications for conservation management of a socially intelligent species

  • Authors: Honiball, Terry-Lee
  • Date: 2024-12
  • Subjects: Spotted hyena -- Behavior -- South Africa , Wildlife conservation -- South Africa , Wildlife management -- South Africa
  • Language: English
  • Type: Doctoral theses , text
  • Identifier: http://hdl.handle.net/10948/68884 , vital:77159
  • Description: It is important to understand the impact of fenced protected area management on the behaviour and fitness of less popular species, such as the spotted hyeana (Crocuta crocuta), that have been historically overlooked in species management across protected areas. As a result of this oversight, hyaena population densities have reached high levels, making it critical to study the effects of fenced protected area management on these species. There is a lack of understanding of how species adapt to the potentially high-pressure systems (through the restriction of resources spatially) created by fenced protected areas and the intrinsic effects that management regimes may have on wildlife. Due to the spotted hyaena’s high behavioural plasticity, they make excellent candidates to explore the effects of management regimes in fenced protected areas while enhancing our understanding of spotted hyaena ecology. Therefore, the aim of this study was to explore the ecology and social behaviour of high density spotted hyaena populations in fenced protected areas to understand the effects of different management regimes and how spotted hyaenas respond to these differing pressures. This was achieved through four main objectives which consider different aspects of spotted hyaena ecology and the influence of management regimes and environmental variables in two fenced protected areas in South Africa; Madikwe Game Reserve (a socio-economically incentivised reserve) and Addo Elephant National Park (a reserve incentivised by the promotion of biodiversity), between 2021 and 2023. This study explored 1) range residency patterns and third order habitat selection in spotted hyaena movement, 2) interspecific interactions at shared food sources to understand the role of lion, Panthera leo, and spotted hyaenas dynamics in top-down pressure in carnivore structure, 3) territorial interactions when defending resources to understand spotted hyaena social dominance when occurring at high densities, 4) welfare considerations and allostatic load of spotted hyaenas, and additionally we provided insight into the social hierarchy disruptions which occur when removing the matriarch from a clan through an opportunistic record. By assessing the effects of socio-economic or biodiversity driven management regimes, this study provided novel accounts of social behaviour and responses of spotted hyaenas to pressures in fenced protected areas, highlighting the top-down pressure that lions have on multiple aspects of spotted hyaena functioning. Road networks and infrastructure in fenced protected areas were generally utilised by spotted hyaenas and despite high abundance, prey availability remained an important aspect of spotted hyaena ecology regardless of management regimes. Further, we showed that when food is abundant, spotted hyaenas are tolerant of subordinate carnivores, which emphasises their dynamic behavioural plasticity. We showed that spotted hyaenas gauge territorial responses according to the perceived threat and are less tolerant to familiar intruders than to unfamiliar individuals, which is an important inbreeding avoidance tactic that remains in place in fenced protected areas. And lastly, we showed that management regimes influence the adrenal function of spotted hyaenas, where fenced protected areas incentivised by wildlife photographic tourism may negatively affect species fitness through elevated epidandrosterone levels over time. However, spotted hyaenas appear to have adapted to elevated hormone levels, thus not affecting fecundity in fenced protected areas, resulting in high density populations. This study provides a holistic overview of the effects of management regimes on spotted hyaenas in fenced protected areas and provides insights into how spotted hyaenas adapt to pressures when occurring at high densities in these areas. This study contributes to the understanding of spotted hyaena ecology and the intrinsic effects on wildlife of different approaches to management regimes in fenced protected areas. , Thesis (PhD) -- Faculty of Science, School of Environmental Sciences, 2024
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  • Date Issued: 2024-12

Solution of some cross-diffusion equations in biosciences using finite difference methods and artificial neural networks

  • Authors: de Waal, Gysbert Nicolaas
  • Date: 2024-12
  • Subjects: Mathematics , Difference equations , Functional equations
  • Language: English
  • Type: Master's theses , text
  • Identifier: http://hdl.handle.net/10948/68829 , vital:77121
  • Description: In this dissertation, three cross-diffusion models which require positivity-preserving solutions are solved using standard and nonstandard finite difference methods and physics-informed neural networks. The three models are a basic reaction-diffusion-chemotaxis model, a convective predator-prey pursuit and evasion model, and a two-dimensional Keller-Segel chemotaxis model. All three models involve systems of nonlinear coupled partial differential equations subject to some specified initial and boundary conditions for which no exact solution is known. It is not possible to obtain the stability region of the standard finite difference methods for the three models theoretically and therefore a range of values of temporal step size at a given spatial step size for reasonable solutions is obtained by running some numerical experiments. It is observed that the standard finite difference schemes are not always positivity-preserving, and this is why nonstandard finite difference schemes are necessary. Chapter 1 provides some background detail on partial differential equations, cross-diffusion equations, finite difference methods, and artificial neural networks. In Chapter 2, the cross-diffusion models considered in this dissertation are provided, namely a basic reaction-diffusion–chemotaxis model for two cases, a convective predator-prey pursuit and evasion model, and a two-dimensional Keller-Segel chemotaxis model for two cases. In Chapter 3, the basic reaction-diffusion–chemotaxis model is solved for the two cases using some standard and nonstandard finite difference schemes. It is determined that the standard methods give reasonable positivity-preserving numerical solutions if the temporal step size, 𝑘, is chosen such that 𝑘 ≤ 0.25 with the spatial step size, ℎ, fixed at ℎ = 1.0. Two nonstandard finite difference methods abbreviated as NSFD1 and NSFD2 are considered from Chapwanya et al. (2014). It is shown that NSFD1 preserves the positivity of the continuous model if the following criteria are satisfied: 𝜙(𝑘)[𝜓(ℎ)]2=12𝛾≤12𝜎+𝛽 and 𝛽≤𝜎. NSFD1 is modified to obtain NSFD2, which is positivity-preserving if 𝑅=𝜙(𝑘)[𝜓(ℎ)]2=12𝛾 and 2𝜎𝑅≤1, that is, 𝜎≤𝛾. In this work, it is shown that NSFD2 does not always achieve consistency, and it is proven that consistency can be achieved if 𝛽→0 and 𝑘ℎ2→0. Lastly, it is demonstrated that the numerical rate of convergence in time of the finite difference methods is approximately one for case 2 of the chemotaxis model. In Chapter 4, one standard and two nonstandard finite difference methods are constructed to solve the convective predator-prey model. Through some numerical experiments, it is observed that reasonable , Thesis (MSc) -- Faculty of Science, School of Computer Science, Mathematics, Physics and Statistics, 2024
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  • Date Issued: 2024-12

Song lyrics and protest discourse in communally composed music in South Africa

  • Authors: Pungu-Pungu, Phakamani Patrick
  • Date: 2024-12
  • Subjects: Songs -- Texts -- South Africa , Lyric writing (Popular music) , Music
  • Language: English
  • Type: Master's theses , text
  • Identifier: http://hdl.handle.net/10948/70393 , vital:78346
  • Description: The study examines the function of communally composed protest song lyrics in South Africa. To explore the aims of the study, the songs composed by community members in South Africa are used as data for the content analysis. This is because the data(songs) will be analysed using content analysis. This serves as a tool to understand the messages in the song lyrics by identifying themes that emerge in the songs and their relevance to human and social injustices faced by marginalised people in the past and present. From this point, the study is approached from a decolonial perspective. The study argues that communally composed protest songs by Black people in South Africa are a historical reference for the people. Furthermore, they (communally composed protest songs) serve as a vital mode that has preserved Black languages under the colonial system of apartheid and maintained the Black oral archival system. This is an integral part of Black culture and tradition. Communally composed protest songs in South Africa are valuable in the fight against social injustice and they authenticate the oral traditions of the Black population. Moreover, context in understanding the lyrics of communally composed protest lyrics is crucial because it adds value to the interpretation of the songs. , Thesis (MMus) -- Faculty of Humanities, School of Visual and Performing Arts, 2024
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  • Date Issued: 2024-12

Strategies to optimize quality of nursing care of patients in public hospitals in the Bono Region, Ghana

  • Authors: Atinga Ba-Etilayoo
  • Date: 2024-12
  • Subjects: Nursing -- Ghana , Nurse and patient , Communication in nursing
  • Language: English
  • Type: Doctoral theses , text
  • Identifier: http://hdl.handle.net/10948/69749 , vital:78016
  • Description: The quality of nursing care delivery is closely tied to positive patient outcomes and satisfaction. However, in Ghana's public hospitals, particularly in the Bono region, the standard of nursing care often falls short. Media reports have highlighted instances of poor nursing care, leading to increased patient morbidity and mortality in this area. Consequently, this study aimed to develop strategies that could be implemented by stakeholders to optimize the quality of nursing care for patients in public hospitals within the Sunyani municipality in the Bono region of Ghana. The Donabedian model of quality was the theoretical framework that underpinned this study. A qualitative, explorative, descriptive and contextual research design was employed. The study was conducted in four phases: Phase One: This empirical phase explored and described participants' perceptions of nursing care quality in Bono region's public hospitals. Data were collected through semi-structured interviews including purposively selected patient participants (n=18), professional nurses (n=18) and nurse managers (n=3) and analysed qualitatively following Creswell and Tesch’s (2021) six-step process. From this analysis, three main themes related to perceptions emerged-facilitators of, barriers to and outcomes of quality nursing care—and were thoroughly discussed. Phase Two: An integrative literature review was conducted to search, select, appraise, extract, and synthesise existing relevant literature on quality nursing care in public hospitals of lower to middle-income countries (LMICs). This review followed four stages recommended by Whittemore and Knafl (2005). The identified literature was critically appraised using the John Hopkins Nursing Evidence and Non-Research Evidence appraisal tools. The appraised literature was analysed, yielding nine strategies for optimizing the quality of nursing care in public hospitals from 12 articles under two themes: “Daily nursing care-related strategies” and “Organizational related strategies”. Phase Three: The findings from Phases One and Two were synthesised to develop a conceptual framework for strategies to optimize quality nursing care in Bono region's public hospitals. This framework was based on Dickoff et al.’s (1968) theory development outline. The resulting framework guided the drafting of the (I-CARE) strategies, an acronym for Implementing ABSTRACT v organizational strategies, Commitment to attributes and practices, Augmenting outcomes, Rendering holistic and patient-centered care, and Enhancing resources and support for quality nursing care. Phase Four: The I-CARE strategies were reviewed and validated by four experts with extensive backgrounds in strategy development and quality nursing care. The experts' modifications and recommendations were incorporated in finalizing the strategies. The strategies, when implemented, are expected to enhance the optimization of nursing care quality in Bono region's public hospitals, ultimately leading to better patient outcomes and satisfaction. , Thesis (PhD) -- Faculty of Health Sciences, School of Clinical Care & Medicinal Sciences, 2024
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  • Date Issued: 2024-12

Student teacher's experiences of teaching mathematics using isiXhosa in foundation phase classrooms during teaching practice

  • Authors: Bangiso, Innocentia Queen Zintle
  • Date: 2024-12
  • Subjects: Mathematics -- Study and teaching , Native language and education -- Africa , African languages -- Study and teaching
  • Language: English
  • Type: Master's theses , text
  • Identifier: http://hdl.handle.net/10948/68297 , vital:76972
  • Description: In South Africa, learning in the Foundation Phase happens in a child’s home language, thus all eleven official languages, nine of them being African languages, must and are used as languages of teaching and learning in this phase. Teacher training, however, does not happen in all eleven official languages. The dominant language of training teachers across the country is English, even in classroom contexts where the language of learning and teaching may be an African language. This raises concerns about whether student teachers trained in English can translate mathematics content knowledge into an African language. This is particularly concerning given the country’s consistent underperformance in mathematics and literacy. Against this backdrop, this qualitative study aimed to explore Foundation Phase student teachers’ perspectives on their experiences of teaching mathematics using isiXhosa during teaching practice. The question that this study sought to answer was: what are student teachers’ perspectives on their experiences of teaching mathematics in isiXhosa during teaching practice? Drawing upon classroom observations and semi-structured individual interviews as the primary methods of data collection, the study explored the mediation of mathematics learning using isiXhosa, the pedagogical challenges encountered by student teachers, the strategies employed to address these challenges, and the influence of university training on their preparation. Findings reveal a significant discrepancy between the language of instruction used in university training which is English, and the language required for teaching practice which is isiXhosa. Student teachers expressed struggles in translating theoretical knowledge into practical application, leading to diminished confidence and pedagogical inefficacy. However, participants also demonstrated resilience through innovative strategies such as code-switching, visual aids, and collaborative learning approaches. The study highlights the urgent need for comprehensive language support and pedagogical training programmes to bridge the gap between theory and practice in isiXhosa-medium mathematics instruction. Recommendations are provided for educational institutions, especially the case study university, to enhance the preparation of student teachers and promote effective mathematics education in multilingual contexts. , Thesis (MEd) -- Faculty of Education, School of Primary School Education: Foundation Phase, 2024
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  • Date Issued: 2024-12

Studies on soil acidity management strategies for sustainable agriculture

  • Authors: Swart, Nicolas
  • Date: 2024-12
  • Subjects: Soil acidity , Soil fertility , Sustainable agriculture
  • Language: English
  • Type: Master's theses , text
  • Identifier: http://hdl.handle.net/10948/69475 , vital:77260
  • Description: Soil acidity is a widespread problem which reduces plant growth and yield. There are calls for alternative crop and soil management strategies that can be used by farmers to deal with soil acidification in a sustainable manner. Current literature suggests that the benefits of sustainable soil management systems on soil acidity are highly variable, and within the context of conservation agriculture (CA), farmers need recommendations for techniques to improve liming efficiency. Such techniques include acid resistant cultivars and soil amendments such as biochar. However, dedicated scientific research is still needed to increase our understanding of the benefits of integrating various sustainable agriculture approaches on reducing the acidity on cropped lands. A series of experiments were thus conducted to test whether the integration of reduced lime dosages with organic amendments such as biochar, along with acid resistant wheat cultivars could improve nutrient availability and reduce the harms of acidity on plant roots. It was hypothesised that if lower than recommended doses of lime are applied in combination with biochar and acid resistant cultivars, there will be significant improvement of nutrient availability, soil acidity amelioration benefits and crop growth. The first experiment was a 60–day incubation trial to examine the interaction effects of reduced lime application rates and black wattle (Acacia mearnsii) biochar on the acidity and plant nutrient availability of a sandy clay loam, acidic podzolic soil. The changes in pH water (pHw) across treatments were monitored at 10-day intervals over the incubation period. Additionally, the initial and final status of each treatment in terms of essential macro-and micronutrients, pH(KCl), extractable aluminium (ext Al), exchangeable acidity (EA) and acid saturation (AS) were also measured. The second experiment examined the genotype × biochar × lime interaction effects on wheat plant root growth in the acid soil. Soil incubation results showed that the interaction effect of lime rate and biochar was not significant (p>0.05) for any of the tested soil nutrient availability and soil acidity parameters, except for pHw. However, lime rate effects were significant (p<0.05) on AS, EA, pH(KCl) and ext Al. As lime rate increased, the acidity decreased. Increasing the lime application rate significantly (p<0.05) enhanced the cation exchange capacity (CEC), calcium (Ca), magnesium (Mg) and phosphorous (P), but decreased potassium (K) and sulphur (S). The availability of micro-nutrients namely copper (Cu), iron (Fe), manganese (Mn) and zinc (Zn) also decreased as the lime rate increased. Biochar effects on EA, AS, pH(KCl) and ext Al were not significant (p>0.05). However, the biochar significantly reduced the availability of Ca and Mn but did not have a significant effecton all the other nutrients at the tested application rates. Unenriched biochar at 10 t ha-1 had an acidifying effect on the soil as it increased EA, when compared to enriched biochar. The significant (p <0.05) biochar × lime × time interaction effect on pHw showed that biochar applied without lime increased pHw, and the benefits were greatest at 10 t ha-1 biochar application rate. Similarly, lime applied without biochar also had a significant positive effect on pHw and the benefit increased at higher lime application rates. After 60 days of incubation, the lime applied at the highest rate of 5 t ha-1 without biochar (0 t ha-1 biochar) had the highest final pHw value. The 3-way interaction of lime, biochar and genotype was not significant (p>0.05). Koonap, the acid tolerant wheat variety outperformed the sensitive variety, Gariep under all treatments in the acid soil, as expected. There was, however, a significant (p<0.05) lime rate × biochar interaction. The highest application rates of lime (5 t ha-1) and biochar (10 t ha-1) were the best combination for root length for both the varieties. Overall, these results suggested a possible buffering effect of biochar at low lime application rates, thus limited benefits of combining reduced lime doses with biochar on reducing soil acidity or enhancing nutrient availability. The null hypothesis was thus rejected, and it was concluded that co-application of reduced lime rates and biochar will not significantly enhance benefits of liming. However, a positive interaction from co-application of biochar and lime on both pH and plant growth is possible at high application rates of both biochar and lime. , Thesis (MSc) -- Faculty of Science, School of Natural Resource Science and Management, 2024
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  • Date Issued: 2024-12

Supramolecular chemistry considerations of fluorenyl-derived host compounds

  • Authors: McFarlane, Duncan William
  • Date: 2024-12
  • Subjects: Supramolecular chemistry , Organic compounds , Chemistry, Organic
  • Language: English
  • Type: Master's theses , text
  • Identifier: http://hdl.handle.net/10948/69371 , vital:77227
  • Description: This work examined various supramolecular aspects of 9-fluorenone-derived host compounds, namely 4,4’-(9-fluorenylidene)diphenol (H1), 9,9-(1,4-phenylene)bis(fluoren-9-ol) (H2), 9,9- (ethyne-1,2-diyl)bis(fluoren-9-ol) (H3) and 9,9-(biphenyl-4,4-diyl)bis(fluoren-9-ol) (H4). These compounds were successfully synthesized and then screened for their host ability for, and host behaviour in, various organic compounds. At the outset, molecular modelling calculations were carried out on each of the four host compounds. Various structural parameters and the geometries of the low energy conformers that were calculated were then compared with these aspects of the guest-free host molecules obtained from single crystal X-ray diffraction (SCXRD) analysis. The host behaviour of H1 was, furthermore, assessed in the presence of four alkylnitriles, namely acetonitrile (ACE), acrylonitrile (ACRY), propionitrile (PROP) and butyronitrile (BUT). All four guests complexed with H1 with 1:1 host:guest (H:G) ratios. From SCXRD analyses, each of the complexes crystallized in the monoclinic crystal system and the centrosymmetric space group P21/n, and the host packing was isostructural in each instance. The complexes were stabilized by a plethora of short inter- and intramolecular contacts. The thermal stabilities of the four complexes were also examined together with Hirshfeld surface considerations. Finally, lattice energy calculations were carried out and the results of these compared with the relative thermal stabilities of the four complexes. The compounds H2 and H3 were examined for their selectivity behaviour in mixtures of aniline, N-methylaniline and N,N’-dimethylaniline (ANI, NMA and DMA). Both host compounds were able to form complexes with ANI and DMA with various H:G ratios, while only H3 possessed enclathration ability for NMA (H:G 1:1). SCXRD analyses showed that all of the complexes were stabilized by means of classical (host)O‒H···N(guest) hydrogen bonds in addition to other short contacts. Equimolar binary guest competition experiments with H2 revealed an extremely high host selectivity for DMA (ANI/DMA and DMA/NMA experiments furnished crystals with > 91% DMA), while the experiment with all three anilines present also resulted in a complex with an , Thesis (MSc) -- Faculty of Science, School of Biomolecular & Chemical Sciences, 2024
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  • Date Issued: 2024-12

Synthesis of two tartaric acid-derived host compounds and their behaviour in mixed pyridines and mixed heterocyclic guest compounds

  • Authors: Recchia, Daniella Loridana
  • Date: 2024-12
  • Subjects: Compounds -- guest/host , Chemistry, Organic , Chemistry
  • Language: English
  • Type: Master's theses , text
  • Identifier: http://hdl.handle.net/10948/69441 , vital:77256
  • Description: The host compounds (4R,5R)-bis(diphenylhydroxymethyl)-2-spiro-1’-cyclopentane-1,3-dioxolane (TADDOL5) and (4R,5R)-bis(diphenylhydroxymethyl)-2-spiro-1’-cyclohexane-1,3-dioxolane (TADDOL6) were successfully synthesized after initially reacting diethyl tartrate with either 1,1-dimethoxycyclopentane or 1,1-dimethoxycyclohexane to afford the intermediates diethyl 2-spiro-1’-cyclopentane-1,3-dioxolan-4,5-dicarboxylate or diethyl 2-spiro-1’-cyclohexane-1,3-dioxolan-4,5-dicarboxylate. These were then each subjected to a Grignard addition reaction with PhMgBr to furnish TADDOL5 and TADDOL6 in reasonably high yields (77 and 80%, respectively). Computational calculations were performed on TADDOL5 and TADDOL6 using the software programs Avogadro and ORCA. The optimised geometries of these host molecules were obtained using the MMFF94 force field in Avogadro, while ORCA was used to perform the computational modelling at the BLYP level using the 6-31G*, 6-31G**, 6-311G* and 6-311G** basis sets and, also, the B3LYP functional (with the same basis sets) to obtain the three lowest energy conformers. The final geometries of each conformer for both TADDOL5 and TADDOL6 at the B3LYP 6-311G* level were overlaid with the molecules obtained from their crystal structures. Significantly different geometries were thus noted for the calculated conformers compared with the guest-free TADDOL5 and TADDOL6 structures obtained from the SCXRD experiments. When TADDOL5 was crystallized independently from each of PYR, 2MP, 3MP and 4MP, 1:1 H:G inclusion complexes formed in each instance. This host compound was then investigated for its host separation ability of mixed pyridines through supramolecular chemistry protocols. These mixed guest experiments revealed that TADDOL5 possessed a notable selectivity towards 3MP and PYR (in the absence of 3MP) followed by 4MP and 2MP, and it was shown that TADDOL5 is a suitable host candidate for the separation of many of the mixed pyridines employed here. The results of the SCXRD analyses indicated that the only significant (host)π···π(guest) stacking interaction present was between TADDOL5 and the most favoured guest species PYR and 3MP. Furthermore, significantly shorter (host)O‒H···N(guest) hydrogen bonds were also observed in the complexes formed between this host compound and 3MP and PYR compared with these bonds involving disfavoured 4MP and 2MP. Hirshfeld surface considerations provided an explanation for the affinity of TADDOL5 for PYR (but not 3MP), while thermal analyses successfully explained this affinity: the 3MP-containing complex with the most preferred guest species was the most thermally stable one, followed by TADDOL5·PYR, as obtained through a consideration of the Ton values (the temperature at which the guest release event initiated) of the four complexes. As with TADDOL5, TADDOL6 formed 1:1 H:G inclusion compounds with each of the four pyridines. TADDOL6 was, furthermore, also assessed for its separation ability for mixed pyridines, and these guest competition experiments showed that the selectivity of TADDOL6 was for PYR and 3MP (in the absence of PYR), followed by 4MP and 2MP. (Interestingly, TADDOL5 preferred 3MP and then PYR, while both host compounds disfavoured 4MP and 2MP.) The results obtained in this work indicated that TADDOL6 may also serve as an efficient host candidate for the separation of many of these pyridyl solutions. SCXRD experiments demonstrated that the only significant (host)π···π(guest) stacking interactions were those between TADDOL6 and preferred PYR and 3MP, as was the case for TADDOL5. These experiments also revealed that the strongest (host)O‒H···N(guest) hydrogen bonds were between TADDOL6 and these favoured guest species. A consideration of Hirshfeld surfaces and quantification of the (guest)N···H(host) intermolecular interactions correlated with the host selectivity order, as did thermal analyses, where the Ton values confirmed that the thermal stabilities of these complexes decreased in the guest order PYR > 3MP > 4MP > 2MP. The behaviour of TADDOL5 was further investigated in guest compounds DIO, PYR, PIP and MOR. Each guest solvent formed 1:1 H:G inclusion complexes with the host species, with the exception of DIO, which formed a 2:1 H:G complex. Mixed guest experiments revealed a clear preference for PIP and MOR, while PYR and DIO were less favoured. The host selectivity was demonstrated to be in the order PIP > MOR > PYR > DIO. SCXRD experiments showed that TADDOL5 formed a much shorter (and more linear) (host)O‒H···N(guest) hydrogen bond with the most favoured guest, PIP, compared to those involving MOR and PYR. A (host)O‒H···O(guest) hydrogen bond was also observed in the DIO-containing inclusion complex. A consideration of the Hirshfeld surface interactions was not useful in explaining the host selectivity order for these heterocyclic guests, but thermal analyses confirmed that the most stable complex was the one with favoured PIP, followed by those with PYR, MOR and DIO. TADDOL6, on the other hand, formed 1:1 H:G inclusion compounds with all four of the heterocyclic guest solvents. Experiments in mixed guests showed that the selectivity of this host compound for these guests was in the order PYR > PIP > MOR > DIO, which differed from the TADDOL5 (which favoured PIP and then MOR). Interestingly, the strongest classical hydrogen bond was not formed with the most favoured guest PYR, but with PIP instead (this bond with TADDOL5 was also strongest with PIP, but PIP was favoured in that work). Hirshfeld surface investigations again were not useful in understanding the host selectivity behaviour. However, thermal analyses agreed with the observations made in the mixed guest experiments: the most stable complex was with PYR (favoured) and the least stable one was with DIO (least preferred). , Thesis (MSc) -- Faculty of Science, School of Biomolecular & Chemical Sciences, 2024
  • Full Text:
  • Date Issued: 2024-12

Synthesis of two tartaric acid-derived host compounds and their behaviour in mixed pyridines and mixed heterocyclic guest compounds

  • Authors: Recchia, Daniella Loridana
  • Date: 2024-12
  • Subjects: Complex compounds -- Synthesis , Chemistry , Chemistry, Organic
  • Language: English
  • Type: Master's theses , text
  • Identifier: http://hdl.handle.net/10948/69445 , vital:77255
  • Description: The host compounds (4R,5R)-bis(diphenylhydroxymethyl)-2-spiro-1’-cyclopentane-1,3-dioxolane (TADDOL5) and (4R,5R)-bis(diphenylhydroxymethyl)-2-spiro-1’-cyclohexane-1,3-dioxolane (TADDOL6) were successfully synthesized after initially reacting diethyl tartrate with either 1,1-dimethoxycyclopentane or 1,1-dimethoxycyclohexane to afford the intermediates diethyl 2-spiro-1’-cyclopentane-1,3-dioxolan-4,5-dicarboxylate or diethyl 2-spiro-1’-cyclohexane-1,3-dioxolan-4,5-dicarboxylate. These were then each subjected to a Grignard addition reaction with PhMgBr to furnish TADDOL5 and TADDOL6 in reasonably high yields (77 and 80%, respectively). Computational calculations were performed on TADDOL5 and TADDOL6 using the software programs Avogadro and ORCA. The optimised geometries of these host molecules were obtained using the MMFF94 force field in Avogadro, while ORCA was used to perform the computational modelling at the BLYP level using the 6-31G*, 6-31G**, 6-311G* and 6-311G** basis sets and, also, the B3LYP functional (with the same basis sets) to obtain the three lowest energy conformers. The final geometries of each conformer for both TADDOL5 and TADDOL6 at the B3LYP 6-311G* level were overlaid with the molecules obtained from their crystal structures. Significantly different geometries were thus noted for the calculated conformers compared with the guest-free TADDOL5 and TADDOL6 structures obtained from the SCXRD experiments. When TADDOL5 was crystallized independently from each of PYR, 2MP, 3MP and 4MP, 1:1 H:G inclusion complexes formed in each instance. This host compound was then investigated for its host separation ability of mixed pyridines through supramolecular chemistry protocols. These mixed guest experiments revealed that TADDOL5 possessed a notable selectivity towards 3MP and PYR (in the absence of 3MP) followed by 4MP and 2MP, and it was shown that TADDOL5 is a suitable host candidate for the separation of many of the mixed pyridines employed here. The results of the SCXRD analyses indicated that the only significant (host)π···π(guest) stacking interaction present was between TADDOL5 and the most favoured guest species PYR and 3MP. Furthermore, significantly shorter (host)O‒H···N(guest) iv hydrogen bonds were also observed in the complexes formed between this host compound and 3MP and PYR compared with these bonds involving disfavoured 4MP and 2MP. Hirshfeld surface considerations provided an explanation for the affinity of TADDOL5 for PYR (but not 3MP), while thermal analyses successfully explained this affinity: the 3MP-containing complex with the most preferred guest species was the most thermally stable one, followed by TADDOL5·PYR, as obtained through a consideration of the Ton values (the temperature at which the guest release event initiated) of the four complexes. As with TADDOL5, TADDOL6 formed 1:1 H:G inclusion compounds with each of the four pyridines. TADDOL6 was, furthermore, also assessed for its separation ability for mixed pyridines, and these guest competition experiments showed that the selectivity of TADDOL6 was for PYR and 3MP (in the absence of PYR), followed by 4MP and 2MP. (Interestingly, TADDOL5 preferred 3MP and then PYR, while both host compounds disfavoured 4MP and 2MP.) The results obtained in this work indicated that TADDOL6 may also serve as an efficient host candidate for the separation of many of these pyridyl solutions. SCXRD experiments demonstrated that the only significant (host)π···π(guest) stacking interactions were those between TADDOL6 and preferred PYR and 3MP, as was the case for TADDOL5. These experiments also revealed that the strongest (host)O‒H···N(guest) hydrogen bonds were between TADDOL6 and these favoured guest species. A consideration of Hirshfeld surfaces and quantification of the (guest)N···H(host) intermolecular interactions correlated with the host selectivity order, as did thermal analyses, where the Ton values confirmed that the thermal stabilities of these complexes decreased in the guest order PYR > 3MP > 4MP > 2MP. The behaviour of TADDOL5 was further investigated in guest compounds DIO, PYR, PIP and MOR. Each guest solvent formed 1:1 H:G inclusion complexes with the host species, with the exception of DIO, which formed a 2:1 H:G complex. Mixed guest experiments revealed a clear preference for PIP and MOR, while PYR and DIO were less favoured. The host selectivity was demonstrated to be in the order PIP > MOR > PYR > DIO. SCXRD experiments showed that TADDOL5 formed a much shorter (and more linear) (host)O‒H···N(guest) hydrogen bond with the most favoured guest, PIP, compared to those involving MOR and PYR. A (host)O‒H···O(guest) hydrogen bond v was also observed in the DIO-containing inclusion complex. A consideration of the Hirshfeld surface interactions was not useful in explaining the host selectivity order for these heterocyclic guests, but thermal analyses confirmed that the most stable complex was the one with favoured PIP, followed by those with PYR, MOR and DIO. TADDOL6, on the other hand, formed 1:1 H:G inclusion compounds with all four of the heterocyclic guest solvents. Experiments in mixed guests showed that the selectivity of this host compound for these guests was in the order PYR > PIP > MOR > DIO, which differed from the TADDOL5 (which favoured PIP and then MOR). Interestingly, the strongest classical hydrogen bond was not formed with the most favoured guest PYR, but with PIP instead (this bond with TADDOL5 was also strongest with PIP, but PIP was favoured in that work). Hirshfeld surface investigations again were not useful in understanding the host selectivity behaviour. However, thermal analyses agreed with the observations made in the mixed guest experiments: the most stable complex was with PYR (favoured) and the least stable one was with DIO (least preferred). , Thesis (MSc) -- Faculty of Science, School of Biomolecular and Chemical Sciences, 2024
  • Full Text:
  • Date Issued: 2024-12

Synthesis, X-Ray characterization, spectroscopic and Hirshfeld surface analysis of dimeric metal centers featuring phenacyl-esters

  • Authors: Qomfo, Vuyiseka
  • Date: 2024-12
  • Subjects: Spectrum analysis , Spectroscopic imaging , Diagnostic imaging -- Digital techniques
  • Language: English
  • Type: Master's theses , text
  • Identifier: http://hdl.handle.net/10948/69426 , vital:77254
  • Description: In this study, the synthesis and characterization of carboxylate paddlewheel copper complexes were investigated and reported. The complexes consist of O-, and N- donor ligands which coordinated in the apical positions of the copper (II) paddlewheel complexes. The primary focus was the investigation of the influence of the incoming substituents on the structure; more especially with regards to the spectral properties and thermal properties of the synthesized compounds. Synthesized complexes ranged from simple mononuclear complexes and dinuclear dimers to supramolecular 1D networks and a tetranuclear copper (II) compound. Characterization of complexes was done using analytical, and spectroscopic techniques such as single crystal diffraction studies, FT-IR spectroscopy, thermal analysis and Hirshfeld surface analysis. Structural analysis of the mononuclear complex obtained in the reaction of the Cu2(o-CH3-PhCO2)4(THF)2 with the ligand ,2-oxo-phenylethylnicotinate, revealed a square-planar geometry. The series of dinuclear paddlewheel complexes obtained with ligands (L = THF (1), C4H8O (2), C14H11NO3 (3)) revealed a square pyramidal geometry with the methyl-substituted phenyl carboxylate groups bridging the two copper atoms in the syn-syn coordination mode. Extended supramolecular complexes were synthesized via the reaction of three synthesized structurally bifunctional organic ligands and the tetrakis(μ-carboxylato-O,O)dicopper(II) core. Two of the six reactions synthesized successfully to form paddlewheel cage type structures; resulting in dinuclear paddlewheel complexes with four carboxylate ligands occupying the equatorial positions and the bifunctional ligands coordinating in the apical positions. Four of the nine reactions produced mononuclear copper complexes. Due to the inconsistent power supply because of load-shedding, the other three crystals synthesized could not be confirmed by single-crystal diffraction before the submission of this thesis. , Thesis (MSc) -- Faculty of Science, School of Biomolecular & Chemical Sciences, 2024
  • Full Text:
  • Date Issued: 2024-12
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