4. Electronic Theses and Dissertations (ETDs) - Faculties submissions
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Item Low-temperature electronic transport of metal doped carbon nanotube molecular hybrids and Nitrogen-doped nanocrystalline diamond(University of the Witwatersrand, Johannesburg, 2024-08) Sodisetti, Venkateswara Rao; Bhattacharyya, SomnathThis thesis explores the magnetism and spin-related properties in carbon-based molecular hybrid materials, with a focus on expanding our understanding of low-dimensional carbon structures and their potential electronic applications. The investigation spans from one-dimensional systems, such as carbon nanotubes (CNTs) functionalized with single-molecule magnets (SMMs), to three-dimensional systems like nitrogen-doped ultra nanocrystalline diamond (UNCD). In these carbon structures, electronic transport is intricately tied to microstructural features, such as grain boundaries and impurity clusters, which hold significant potential for the development of all-carbon electronic devices. The research begins with a detailed examination of the chemical functionalization of multi-walled carbon nanotubes (MWCNTs) through controlled acid treatment to achieve precise metal doping. Using Raman spectroscopy and complementary techniques like ICP-MS and ToF-SIMS, we successfully demonstrate how functionalization levels influence the magnetic properties of CNT hybrids loaded with magnetic metals from the lanthanide series (Gd, Tb, Dy). The study reveals that low percentages of metal doping (0.5% to 1.0%) preserve the magnetic bistability of SMMs post-grafting, while higher doping levels lead to complex magnetic behaviors including super paramagnetism, quasi-ferromagnetism, and potential Kondo lattice behavior inCNT-heavy metal systems. We also explore the spin-phonon coupling in Gd-filled double-walled CNTs, where the onset of superparamagnetic properties at low temperatures is coupled with phonon mode stiffening observed via Raman spectroscopy. This enhanced coupling offers promising pathways for developing efficient molecular qubits through the modulation of spin-phonon interactions in one-dimensional systems. The second part of the thesis investigates into the microwave plasma-assisted chemical vapor deposition (MWCVD) growth of nitrogen-doped nanocrystalline diamond (NCD) thin films on different substrates. By pioneering upgrades to the MWCVD system, I was able to achieve reliable growth of high-quality nanocrystalline diamond thin films. Notably, I observed a novel nanostructure, termed Diaphite-a previously unreported feature, in these NCD films, consisting of nanodiamond grains coherently linked with graphene-like rings. This structure, along with the non-equilibrium growth conditions induced by nitrogen doping and secondary nucleation, presents unique polymorphic features in artificially grown diamonds. Detailed low-temperature transport measurements on four different samples—ranging from 7.5% to 20% nitrogen doping—uncovered complex transport phenomena such as 3D weak localization (WL), variable-range hopping (VRH), and unusual magnetoresistance (MR) behavior. In particular, the 7.5% N2-doped UNCD film on quartz exhibited 3D weak localization (WL) at low fields and anti-weak localization (AWL) at higher fields, with distinct magnetoresistance characteristics depending on the direction of the applied magnetic field. The 20% N2-doped films on both quartz and silicon showed more metallic-like behavior, with magneto-resistance characterized by a B1/2 dependence at low temperatures, suggesting an intricate relationship between doping level, microstructure, and electron transport. These findings significantly expand our understanding of the role that microstructural and chemical modifications play in determining the electronic and magnetic properties of carbon-based materials. This work provides a foundational platform for future research into carbon electronics, offering potential breakthroughs in spintronics, molecular transistors, quantum computing, and other advanced electronic applications.Item Beyond the click: Informed consent in the age of cookies(University of the Witwatersrand, Johannesburg, 2024) Finger, Mokone; Visser, C.Rapid evolution of technology and the internet has enabled vast data to be exchanged amongst people. These changes have introduced extraordinary data collecting methods that also recognise traces of personal information when users browse the internet. An example of such a tracking method is a cookie. Cookies, while they serve to enhance user experience, tend to collect and store personal information of data subjects without their knowledge and consent. For this reason, they raise a question of a threat to privacy and consent of data subjects. This research report principally examines the legal sufficiency of a mere click of a button in establishing valid consent for processing of personal information, which includes the collection, storage and transmission of personal information through cookies. The Protection of Personal Information Act 4 of 2013 (the POPI Act) was enacted to give effect to the constitutional right to privacy. Thus, the POPI Act operationalises the constitutional right to privacy by providing a framework for the processing of personal information, even though its application has shortcomings related to consent and cookies. In order to interpret the POPI Act, this paper will integrate the common law and the General Data Protection Regulation 2016/679, based on the adjudicative subsidiarity doctrine, as constitutional backdrop instruments to determine the threshold for consent in the POPI Act when using cookies.Item A practical review of the effectiveness of artificial intelligence in the automated review of legal contracts(University of the Witwatersrand, Johannesburg, 2024) Fouché, Jacques GerritThis research report compares the performance of AI-driven automated contract review platforms with that of human contract reviewers, aiming to see improved effectiveness for the elements of time, cost and quality. An empirical study is done by comparing the specific performance of an automated contract review platform provider, Lawgeex, to the human contract reviewers of a business entity, Endress+Hauser. The results of the effectiveness assessment are reported on through dashboard data and questionnaires to the users of the platform. Recommendations are made both in general and specific to the two entities of the empirical study.Item Oil Price Shocks and Financial Stress in Sub-Saharan African Countries(University of the Witwatersrand, Johannesburg, 2024) Frost, CallumThis study examines the nexus between financial stability and oil shocks within South Africa, a net-oil importer, and Nigeria, a net-oil exporter. A signal theory approach utilising pAUROC analysis is used to capture relevant indicators. Furthermore, sub-market indices are weighted using a diagonal BEKK-GARCH model, allowing for time-varying cross-correlations to determine sub-market weights, allowing the constructed financial stress index (FSI) for each economy to focus on systemic events of financial stress. The FSI for each economy is then incorporated into a SVAR model which disaggregates oil demand shocks into three components (economic activity, oil consumption demand, and oil inventory demand) following the framework of Baumeister and Hamilton (2019) to capture the effects of oil market shocks on financial stability. This paper finds that positive shocks to oil supply, economic activity, and oil inventory demand tend to reduce financial stress in South Africa. Interestingly, demand driven increases in the real price of oil reduces systemic stress, even though the economy is a net-oil importer. Oil supply shocks and economic activity shocks tend to have no significant effect on Nigerian financial stress while demand driven increases to real oil prices tend to decrease financial stress. Interestingly, shock increases in demand for oil inventories tends to raise financial stress.Item Deconstructing the debate around bank account closures on the pretext of institutional reputational risk(University of the Witwatersrand, Johannesburg, 2024) Hayath, Iram; Kawadza, HerbertThe Supreme Court of Appeal in Bredenkamp v Standard Bank found that a bank has a contractual right to close a client’s accounts on reasonable notice, and that a bank is entitled to exercise this right if it perceives that a continued relationship with the client may result in reputational and business risks to the bank (albeit may be premised on allegations which the client denies). Banks have regulatory obligations to (amongst others): (i) manage their reputational risk; and (ii) take steps to avoid their accounts being used by clients to facilitate the proceeds of unlawful activities. Banks are at the receiving end of scrutiny for the latter, including from the media. Banks’ actions of closing accounts for institutional reputational risk are however, often challenged by clients on the basis that these decisions are informed by untrue allegations and are contrary to public policy. A particular consideration is the potential consequences of the clients becoming ‘unbanked’. There are also other issues of contention including that reputational risk is an elusive reason. The competing interests and public policy considerations at play have not yet been adjudicated by our courts. This research report argues that the complexities involved necessitates legislative reform to ensure certainty and fairness on both sides.Item House Prices Against the Wind: Analysis of the use of Monetary Policy to Moderate House Price Bubbles and the Case of New Zealand(University of the Witwatersrand, Johannesburg, 2024) Jinabhai, Nikhil; Creamer, KennethItem The constitutionality of COVID 19 Vaccination Policies and its implications on the right to freedom of religion in South Africa(University of the Witwatersrand, Johannesburg, 2024) Karuaihe, Janee Raahua SiegfriedCovid-19 was declared by the World Health Organisation (WHO) as a disease affecting people over a large geographical area. It caused severe illness to millions of people around the world and the death of over four million people. This impact on people had a direct effect on employers, employees and the workplace. Religions and those practicing their religion weren’t spared from the impact of Covid-19. To control the impact of Covid-19 on the workplace, employers were obligated to take steps to keep the workplace safe and to ensure that businesses can reopen in a manner that would ensure the safety of employees and the public. One of the measures taken by employers to ensure the safety of the workplace was the introduction of vaccination policies. These policies varied from workplace to workplace, but a consistent feature was that employees were required to be vaccinated to return to the workplace. If such workplace were to be implemented without exception, it would fail to recognise the fact that certain religious practices and certain people who practice various religions do not permit vaccines, and where they do, only certain vaccines are allowed. As there is no specific legislation governing the implementation of vaccination policies in the workplace, many employees across South Africa believed these policies unjustifiably limited rights protected by the Constitution, including the right to religion. The courts have accepted that vaccination policies may have the effect of limiting rights that are protected in terms of the Bill of Rights. Still, such limitations may be justified where the employer takes steps and introduces such a policy where necessary to ensure the safety of the workplace.Item In Silico Exploration of Endocannabinoid Receptor–CB1 and CB2–Interactions Comparing Cannabidiol and Cannabidiol Diacetate: A Comprehensive Computational Study(University of the Witwatersrand, Johannesburg, 2024-09) Soobben, Marushka; Achilonu, Ikechukwu Anthony; Sayed, YasienIn the rapidly evolving field of cannabinoid research, acetylated phytocannabinoids such as cannabidiol diacetate (CBDDA) have shown prominence due to its enhanced effects compared to its natural counterpart, cannabidiol (CBD). Despite the growing popularity in the consumption of acetylated phytocannabinoids, in-depth research on its pharmacological impact, especially on CB1 and CB2 receptors, remains scarce. With rising reports of adverse reactions to acetylated phytocannabinoids, a molecular understanding of their interaction with endocannabinoid receptors (CBRs) is imperative. This study aimed to fill this knowledge gap by analysing receptor interactions of CBDDA in comparison with receptor interactions of CBD. The study showed that CBDDA forms stronger interactions with CBRs than CBD. Recognised for its heightened potency, the potential of CBDDA as a biopharmaceutical product was examined. CBR interactions with known endocannabinoids, agonists and inverse agonists validated the computational models used to determine the difference in conformational dynamics upon ligand binding. In this work, bioinformatics, molecular docking, and molecular dynamics (MD) simulations were used to determine the structural differences of CBRs when bound to CBD/CBDDA. Simulations in a 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) and water environment successfully mimicked physiological conditions. Subsequent high-throughput virtual screening (HTVS) was conducted using CBDDA as a reference where ligands 142730975 and 21568811 were identified as the top scoring hits for CB1 and CB2 receptors, respectively. The identification of these ligands via HTVS highlights the therapeutic potential of targeting CBRs and the biopharmaceutical potential of CBDDA. This study elucidates the specific interactions of CBD and CBDDA with CB1 and CB2 receptors, laying a foundation for assessing the safety and efficacy of acetylated phytocannabinoids. Overall, the differential interaction of CBDDA compared to CBD with CBRs suggests that acetylation changes the conformational dynamics of CBRs thereby potentially affecting signalling. The identification of ligands 142730975 and 21568811 as strong interactors with the receptors may provide valuable leads for the development of new cannabinoid-based therapies.Item Realising the right to healthcare: the legislative frameworks pertaining to private health establishments and private healthcare funding models in South Africa(University of the Witwatersrand, Johannesburg, 2024) Labuschagne-Kom, Lindsie; Mahery, Prinslean; Martin, BlakeThe Universal Declaration of Human Rights recognises access to healthcare as a fundamental human right and is guaranteed by the South African Constitution. An analysis of this right reveals that it comprises of two main components, namely financing and delivery of healthcare services. These are fulfilled by the government in the public sector and by private healthcare funders and private health establishments in the private sector. However, an analysis reveals that access to healthcare is substantively inequitable due to the fragmentation of the health system and unveils significant inefficiencies in the private sector that impeded realisation of this right. This dissertation examines the cause of this fragmentation and the inefficiencies within the private healthcare funders and private health establishments market. It investigates how these issues can be resolved to realise the right to healthcare. This study applied a qualitative desktop review of governmental policies, direct and incidental legislation, and multidisciplinary fields of academic reviews such as competition, healthcare, constitutional law and international policies to evaluate the effect of historical, contemporary and prospective policies and legislation, on access to healthcare. This analysis reveals that access to healthcare was historically manipulated to achieve political ideology through a legislative framework that provided the foundation for private funding models and private health establishments to flourish. This occurred at the expense of the public sector and embedded the fragmentation and inefficiencies in the health system. Notwithstanding the enactment of the Constitution, which envisioned a transformed and equal society, access to healthcare remains substantively inequitable. This is due to governmental failings to regulate these stakeholders. Given this state of affairs, the government intends to enact legislative reform through the National Health Insurance Bill to meet its constitutional mandate to realise the right to healthcare. An analysis of the Bill’s framework, however, reveals that it will have a cascading effect with the collapse of the private healthcare funders and private health establishment markets. This will ultimately cause a regression in access to healthcare and impede the practical realisation of this right. An investigation into alternative mechanisms to fulfil the right to healthcare reveals that incorporation and collaboration with private healthcare funders and private health establishments is a pragmatic alternative to the National Health Insurance Bill that will aid with the practical realisation and vindication of this right. These findings indicate the need for government to improve its stewardship of the health system and provide pragmatic solutions to reform the legislative and regulatory frameworks governing these stakeholders to resolve inefficiencies and to foster collaboration to fulfil the right to healthcare.Item The price effects of a hospital merger: a case study of the Mediclinic Southern Africa (Pty) Limited (Mediclinic) and Matlosana Medical Health Services (Pty) Limited (MMHS) merger(University of the Witwatersrand, Johannesburg, 2024) Laurence, Marcelle; Mncube, LibertyThis study evaluates the assessment conducted in the prohibited Mediclinic Southern Africa (Pty) Ltd and Matlosana Medical Health Services (Pty) Ltd (MMHS) proposed merger. The study employs a qualitative approach, centred on a case study methodology, to assess the theories of harm discussed. It aims to provide insights into the adequacy and outcome of the competition authorities’ assessment drawing comparisons to international literature and policy implications. It uses economic theory to analyse and show the significance of robust and nuanced regulatory frameworks in healthcare merger evaluation.