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Development of electrochemical sensors for the detection of mycotoxins in food matrices using functionalised nanocomposites
No full textSubmitted in fulfillment of the requirements of the degree of Doctor of Philosophy in Chemistry, Durban University of Technology, Durban, South Africa, 2023.The analysis of pathogens in foods is of critical importance to ensure consumer safety and quality assurance, as contaminants pose serious risks to public health. Mycotoxins are naturally occurring carcinogenic toxins that arise from specific strains of fungi as they contaminate food. They are found in a wide variety of grains, cereals, and dairy products, causing cancer in both humans and animals. Thus, there is a growing demand for simple, sensitive and inexpensive sensors for mycotoxin detection in lieu of conventionally employed large-scale instrumentation. In this study, the development of electrochemical sensors for the detection of aflatoxin B1 (AFB1), zearalenone (ZEN) and ochratoxin A (OTA) in foods was investigated and presented as three case studies, respectively. In the first case study, an ultrasensitive aptasensor was developed for the indirect detection of AFB1 in the presence of a ferri/ferrocyanide ([Fe(CN)6]3-/4-) redox probe solution. The sensor was constructed by immobilizing an anti-AFB1 aptamer (Apt) to a carboxylated multiwalled carbon nanotube (cMWCNT) and iron oxide (Fe3O4) nanoparticle (NP) composite using a glassy carbon electrode (GCE). This resulted in the development of the GCE/cMWCNTsFe3O4 NP/Apt sensor. An electrochemical response was exhibited from AFB1 applying cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and differential pulse voltammetry (DPV), respectively, utilizing a [Fe(CN)6]3-/4- redox probe prepared in phosphatebuffered saline (PBS) solution with reference to the Ag/AgCl reference electrode under optimized conditions. DPV findings reported very low limits of detection (LOD) and quantification (LOQ) of 0.43 fg mL-1 and 1.44 fg mL-1 respectively in comparison to current literature, over a calibration range of 0.50 fg mL-1 to 5.00 fg mL-1. For real sample analysis, excellent spike recoveries from 95% to 105% were obtained for corn and rice flour. Density functional theory (DFT) was used to propose a reaction scheme by ascertaining the electronic properties of the redox-active functional groups of AFB1. This supported the experimental anodic response findings of DPV. The second case study focused on how PEGylated Fe3O4 NPs and cMWCNTs fabricated on a GCE could be used for the design of an electrochemical sensor for ZEN analysis. The qualitative and quantitative analyses of ZEN were completed using CV, EIS and DPV, respectively, under optimized conditions in a sodium phosphate buffer solution. The developed sensor reported significantly low LODs and LOQs of 0.34 fg mL-1 and 1.12 fg mL-1 respectively, over a calibration range of 1.00 fg mL-1 to 10.00 fg mL-1 by DPV. Excellent spike recoveries ranging from 92% to 106% were obtained for rice and corn flour. The Monte Carlo (MC) adsorption simulation studies predicted the strong interaction of ZEN with the constructed sensor. In the final case study, an OTA electrochemical sensor was designed using a nickel metalorganic framework (Ni-MOF) and carboxylated reduced graphene oxide (cRGO) on a GCE. The detection of OTA was achieved under optimized conditions in PBS solution with the developed GCE/Ni-MOF/cRGO electrode, employing CV, EIS and DPV as electrochemical tools. Applying DPV, the sensor reported very low LODs and LOQs of 3.29 fg mL-1 and 10.97 fg mL-1 respectively, over a calibration range of 10.00 fg mL-1 to 90.00 fg mL-1. Regarding real sample analysis, excellent spike recoveries from 95% to 105% were obtained for corn and rice flour. Molecular dynamics (MD) studies predicted that the Ni-MOF exhibited a strong electrostatic interaction with the OTA analyte, in agreement with the experimental findings. The synthesized nanomaterials (cMWCNTs-Fe3O4 NP, PEG-Fe3O4 NPs/cMWCNTs, and NiMOF/cRGO) utilized in this study were characterized by an array of techniques, including single particle inductively coupled plasma-mass spectrometry (spICP-MS), transmission electron microscopy (TEM), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDS), scanning electron microscopy (SEM), multidetector asymmetrical flow field-flow fractionation (AF4), and Fourier transform infrared spectroscopy (FTIR). Finally, computational modelling studies were undertaken to establish a synergy with the experimental approaches employed in each case study. These methodologies included DFT, docking studies, MC adsorption and MD simulations, which were aimed at predicting and assessing the atomic and molecular interactions between the mycotoxins and their respective electrode systems.
Shifting territories : towards a methodology for a creative emancipatory approach to place-making, the role of Spaza shops in Cornubia, Blackburn, KZN
No full textA thesis submitted in fulfillment of the requirements of the degree of Doctor of Philosophy in Engineering: Architecture, Durban University of Technology, Durban, South Africa, 2023.This research argues that the idea of a ‘breaking new ground’ initiative in urban planning demands the effort of unearthing existing alternative practices and attitudes in the pursuit of spatial justice (Soja 2010). The study is located in Cornubia, a large human settlement development on the north coast of KwaZulu-Natal, Durban, South Africa. Contextualised within the national landscape of state-housing provision, and the theoretical lens of place-making and spatial justice, it aims to offer both theoretical and practical insights into the gap between theory and practice in current participatory practices in planning and housing. It explores how creative methodologies may be useful mechanisms for participatory planning, especially in facilitating and translating how residents in housing developments make meaning out of the places they live in. It engages how these may differ, or not, from meaning-making done by state planners and officials. To demonstrate the argument, the thesis uses the example of spaza shops both as a metaphor and a popular initiative. Following on, it suggests that spaza (as creative impulses) owners could take the form of interlocutors who can facilitate dialogue between official top-down planning and quotidian bottom-up operations within the context of the Cornubia development. In doing so, the potential for dialogue in a creative form that already exists ‘informally’ as the popular innovations/manifestations exemplified in the spaza shop, can be revealed. It is in the interstitial space of misunderstanding, where communication often breaks down between the state and the street, that this research has positioned art/creative practice as a way of opening up dialogue within and between individuals, communities, and the state. In addition, arts-based/informed methods, including the use of drawing, Lego blocks, image theatre (drama), and Scrabble are employed as data-generating tools. Furthermore, workshops, focus groups, and face-to-face interviews are conducted to reflect, articulate and reveal the experience of the participants living in a human settlement and their understanding of space and urban planning. The thesis also draws on a series of interviews with the built environment specialists involved both directly and administratively in the project. The objective is to explore the potential for the conceptualisation of powerful catalysts for transformative forms of politics and for providing new sets of resources for urban and spatial thinking Theoretically, the dissertation argues that spazas should be read as popular culture since popular culture is both evasive and resistant (Fiske 1989) and is created “out of the resources, both discursive and material that are provided by the social system that disempowers [the people]” (Fiske 1989:2). Spazas are creative impulses in their own right, developed organically, as critical responses to an environment which has limited access and spaces for the working-class and poor to exercise their various freedoms whether they be economic, spatial, social or cultural.
An integrated approach to managing single-use-plastics
Get PDFSubmitted in fulfilment of the requirements of the Degree Master of Philosophy: Quality, Durban University of Technology, Durban, South Africa, 2024.Societies’ reliance on plastic materials and excessive consumption off Single-Use-Plastics
(SUP) associated with poor regulations and conglomeration of plastic waste in the
environment has had radical and far-reaching consequences on food chains, strained landfill
territory and declined tourism, to name a few. The expanse of these effects suggests that the
negative impact of SUP warrants urgent attention. There are urgent calls from the Group of
Seven (G7), Group of Twenty (G20) and Brazil, Russia, India, China and South Africa
(BRICS) intergovernmental bodies along with the United Nations Sustainability
Development Goals to control the detrimental effects of SUP. This study aimed to develop an Integrated Quality and Environmental Management System
(IQEMS) to control the consumption, use and pollution caused by SUP in the South African
context. Accordingly, the objectives of this study explored selected quality (ISO 9001:2015)
and environmental Standards (ISO 14001:2015) with their applications and a SWOT analysis
in order to inform the integration process. This study followed a qualitative research approach and gathered data using a systematic
literature review and thematic analyses. Two-hundred and twenty-three articles were selected
from different databases such as Pubmed, Web of Science, Emerald, Scopus and Taylor and
Francis. Some of the keywords that were used to search the databases were “SUP”, “ISO
9001”, “ISO 14001” “Industry 4.0”, “Risk Management”, “Plastic Pollution”, “Integrated
Management Systems” and “SUP regulation”. Following these analyses, the study
Benchmarked different legislative and economic strategies undertaken by other countries for
both the private and public sector to mitigate the impact of SUP and developed an integrated
management system (IQEMS). Thereafter, a perception study, using interviews was
undertaken with experts to determine the usefulness of the proposed IQEMS. The research concluded that the integrative system was useful and the study presented a way
forward for South Africa from the legislative level for both the private and public sectors in
the management of SUP. It is envisaged that the integrated system can assist in developing
guidelines and protocols for the facilitation of active involvement of municipal management
in sustainable programmes. The outcomes of this can spur the development of different niche
markets, thereby stimulating employment and the local economy.
Evaluating the influence of leverage and liquidity on the financial performance of general insurance companies in Sub-Saharan Africa
Get PDFThe factors of the insurance industry’s business performance are of concern to a variety of participants in any economy, such as the government, politicians, policyholders, and speculators. There has been very little research on this issue in Sub-Saharan Africa, with the majority focusing on specific factors that influence the performance of insurance businesses. The purpose of this paper was to evaluate the influence of leverage and liquidity on financial performance of general insurance companies in Sub-Saharan Africa. The study used descriptive correlational techniques to obtain panel data across 113 general insurers operating in Sub-Saharan Africa as of December 31, 2019, for 11 years (2008–2019). The pooled OLS, fixed effects and random effects models were estimated with the financial performance measures (proxied by ROA) as the dependent variables where the Hausman test was employed to test the hypothesis. The study found that there is a negative negligible link between leverage and financial performance, whereas there is a positive association between liquidity and financial performance. The study suggested that proper liquidity management is critical for insurance businesses to enhance a company’s value as well as financial success. The focus should be on establishing a proper asset-liability mix, in which a company’s total liabilities do not exceed its total assets. Furthermore, organizations require cash flow policy recommendations to optimize profit potential while limiting liquidity risk in the financial statement
Intellectual capital and financial performance of South African development community's general insurance companies
Get PDFThe effect of intellectual capital on financial performance was investigated in this paper for the period 2008 to 2019. A total of 696 observations were generated from data collected from 56 general insurance companies in 12 years. The Value Added Intelligent Coefficient Model was used and data was analysed using both static (two stage least square, fixed and random effect) and dynamic panel regression analysis (two step system generalised method of moments). The findings showed a significant and direct relationship between lagged return on assets, intellectual capital and financial performance of insurers in the South African Development Community. Out of the components of intellectual capital, human capital and structural capital are significantly and directly related with return on assets while capital employed is inversely and insignificantly related with return on assets. The control variables-underwriting risk, insurer size and leverage are all inversely and significantly affecting return on assets. Thus, a U-shape relationship exists between intellectual capital and financial performance in general insurance companies in the South African Development Community. Thus, the policy makers-cum-insurers' managers should maximise their intellectual capital as this creates competitive advantage that leads to financial performance drive and wealth generation. The Model used in this study is an important model decision-makers can use to assimilate intellectual capital in their decision-making procedures. This will inadvertently permit insurers to scale themselves according to the intellectual capital efficiencies and advance in strategies that will boost their company's financial performance
Challenges of women entrepreneurship and empowerment in South Africa : evidence from rural areas
Get PDFThis study aims to identify impediments to expanding women-owned businesses in rural areas of South Africa. The study used a quantitative research method to collect data. The study concentrated on 250 female business owners in the rural communities of Hluhluwe, Ulundi, and Eshowe in northern KZN. The study found that the main obstacles to expanding women-owned businesses in rural areas were financial constraints, a lack of education, and inadequate infrastructure. However, these difficulties experienced by women business owners in rural South Africa can be conquered. Overcoming these obstacles could empower women entrepreneurs and stimulate economic growth in rural areas, thus reducing poverty and enhancing the living standards of rural communities. Based on these findings, the study recommends various interventions, such as alternative financing models, targeted education and training programs, and infrastructure development, to support the growth of women-owned enterprises in rural areas. Future research should examine additional issues such as cultural and social hurdles, a lack of access to markets and information, and legal and regulatory restrictions that impede the establishment of women-owned businesses in rural areas
The relationship between macroeconomic factors and profitability of reinsurance companies in Africa : an application of system GMM-Model
Get PDFDespite the known strengths of the reinsurance companies to generate immense profits, evidence from existing literature indicates that the future of the reinsurance companies needs to be more robust to economic deficiencies leading to underperformance. There are many possible factors behind this. However, this study aimed to determine the relationship between macroeconomic factors and the profitability of African reinsurance companies with a Generalized Method of Moments (GMM) model. The study used 121 listed reinsurance companies from 48 African countries using secondary data from year 2008 to 2019. A 1452 observation panel data set was analyzed using conventional least squares and two-step System GMM estimators. The study revealed that GDP, interest rate, and the exchange rate positively impact profitability. In contrast, the inflation rate and money supply revealed a negative and negligible impact on profitability. The input of this research resides in providing new evidence on the macroeconomic factors influencing the profitability of listed reinsurance companies in Africa
Knowledge-based word sense disambiguation for Setswana-English machine translation
Get PDFSubmitted in Fulfilment of the requirements of the Degree of Doctor of Philosophy in Information Technology, Durban University of Technology, Durban, South Africa, 2024.There are several challenges that hinder the development of Setswana-to-English machine translation systems. A key obstacle is the absence of machine-readable knowledge resources. This has
prompted the use of the only accessible data, which originates from the government domain. While
training machine-translation systems using government-domain data can offer specialized language
knowledge, such training introduces obstacles such as limited vocabulary, style variation, bias, and
domain specificity. Furthermore, it is noted in the literature that the ongoing problem of polysemy in a
machine-translation system reduces the overall accuracy. Polysemy is a linguistic phenomenon in which
a single word or phrase has multiple senses, resulting in ambiguity. The task of resolving ambiguity in
natural language processing (NLP) is known as word sense disambiguation (WSD). The concept of
WSD serves as an intermediate task for enhancing text understanding in NLP applications, including
machine translation, information retrieval, and text summarization. Its cardinal role is to enhance the
effectiveness and efficiency of these applications by ensuring the accurate selection of the appropriate
sense for polysemous words in diverse contexts. This study addresses these challenges by proposing
three essential components: a diversity-aware machine-readable knowledge resource for SetswanaEnglish, or the Setswana universal knowledge core (SUKC), a WSD approach to resolving lexical
ambiguity; and a corresponding machine-translation model embedded with a WSD capability.
Setswana-English data was collected from the existing paper-based bilingual dictionaries to achieve
this purpose. Secondly, the study employed professional translators to translate space domain concepts
from English to Setswana. The collected lexicon was integrated into the universal knowledge core
(UKC). The Lesk algorithm which has seen various adaptations by researchers for different languages
over the years was employed to address the inherent polysemy challenges. This study used a simplified,
Lesk-based algorithm to resolve polysemy for Setswana; and used the bidirectional encoder
representations from transformers (BERT) model for Setswana, and cosine similarity measure to embed
Setswana glosses and measure semantic similarity, thus determining the accurate sense. The study
employed a rule-based method embedded with the WSD algorithm for machine translation. The
translation accuracy of the machine-readable dictionary was assessed by employing the developed
machine-translation model; and evaluated using the BLEU score. The proposed model was tested on a
combination of sentences containing both ambiguous words and those without ambiguity; and a higher
BLEU score of 34.89 was achieved.
Total quality management and competitive advantage of manufacturing organizations in the Steel industry Durban Metropolis
Get PDFA dissertation submitted in fulfillment of the requirements for the degree of Master of Management Accounting, Durban University of Technology, Durban, South Africa, 2024.This study investigated total quality management (TQM) and the competitive advantage of manufacturing organizations in the steel industry in the Durban Metropolis. While a few studies have touched on TQM and competitive advantage in Durban, they did not examine TQM and competitive advantage in steel manufacturing organizations in the city. The literature on the context of business competitiveness, total quality principles, process management and top management and other pertinent concepts was reviewed. Purposive sampling was employed to obtain a total of 100 participants from the 23 organizations in the Durban steel industry. A quantitative research design was adopted, with a questionnaire administered to gather data. The data were analyzed using confirmatory factor analysis (CFA), which was employed to prove or disprove the hypotheses, with the results presented in tables and graphs. The findings suggest that employee training, committed management, a customer-focused approach, sound relationships with suppliers, and clear goals would enable organizations in Durban’s steel industry to improve their performance and thus gain a competitive edge. The study contributes to the body of knowledge on TQM in organizations and its impact in the steel manufacturing industry. Further research is recommended to explore the impact of the adoption of TQM among South African organizations.
Determinants of participation of Msunduzi local municipality’s peri-urban households in the digital finance economy
Get PDFSubmitted in fulfillment of the requirements of the degree of Master of Accounting, Durban University of Technology, Durban, South Africa, 2024.Digital finance is an instrument that has the potential of improving access to finance to underprivileged groups such as peri-urban communities. Digital financial tools are capable of achieving traditional crisis management objectives with greater potency and accuracy than was historically possible. The financial services sector is in a process of accelerating change by adopting new business models based on convergent technological developments to increase customer participation in periurban areas. Therefore, the financial services sector can use digital finance to improve the availability of household financial services through diversified financial products, thus promoting the growth of household consumption. However, several studies maintain that determinants of digital finance participation of marginalised households, including peri-urban households, are generally underdetermined. Moreover, there is limited literature on the participation of South African households in the digital economy. Scholarly literature asserts that the level of participation of South Africans in digital finance is concerning. This is largely due to a lack of awareness and knowledge of digital financial services that are available to South African households. This study seeks to bridge that gap by examining the determinants of participation of peri-urban households in digital finance in the financial services sector in KwaZuluNatal, South Africa. A quantitative research approach was adopted to answer the research questions. This method was found to be suitable for this study given that the research objectives can be best measured using a structured survey that is quantitative in nature. The target population of this study consisted of peri-urban households located in the Greater Edendale area, which is the largest peri-urban area within the Msunduzi Local Municipality. The sample size for this study was 384 periurban households which were selected using purposive sampling, derived from nonprobability sampling. The questionnaires were in English and were also translated into isiZulu in order to make it easier for respondents to participate in this study. The Statistical Package for the Social Sciences (SPSS) was used to compile the descriptive statistics. The results of this study indicate that the general public in economically disadvantaged communities participates in digital financial transactions in the financial services sector on a regular basis. A Spearman correlation analysis found a substantial positive link between the usage of digital platforms by peri-urban families and their degree of participation in digital finance. This association was shown to be statistically significant (r = .649, n = 315, p < .001). However, the results of a Mann-Whitney U test showed that there was no statistically significant difference between genders with regard to involvement in digital finance (Z = -1.804, p = .071). A correlation analysis was undertaken to determine whether peri-urban households’ awareness of digital financial services influenced their adoption of digital platforms. The Spearman correlation analysis (r = .768, n = 315, p < .001) showed a strong and significant relationship between peri-urban households’ knowledge and awareness of digital financial services and their use of digital platforms. Additionally, a Spearman correlation analysis (r = -.524, n = 315, p < .001) revealed a significant negative association between peri-urban households’ adoption of digital financial platforms and their digital literacy. This is despite the fact that literature argues that in South Africa, the adoption of digital financial services is negatively affected by a lack of information and knowledge which is prevalent among marginalised communities.