Central University of Technology
  • Bloemfontein, Free State, South Africa
Recent publications
Background HIV recency assays are used to distinguish recently acquired infection from long-term infection among individuals newly diagnosed with HIV. Since 2015, the World Health Organisation recommends the use of an algorithm to assess recency of infections which is based on an HIV recency assay and viral load (VL) quantification. We determined the proportion of recent HIV infections among participants of the VIBRA (Village-Based Refill of Antiretroviral therapy) cluster-randomized trial in Lesotho and assessed risk factors for these recent infections. Methods The VIBRA trial recruited individuals living with HIV and not taking antiretroviral therapy during a door-to-door HIV testing campaign in two rural districts (Butha-Buthe and Mokhotlong). Samples were collected from participants newly diagnosed and tested for HIV recency using the Asanté HIV-1 Rapid Recency Assay and VL using the Roche Cobas System. Clinical and socio-demographic data were extracted from the trial database. Univariate analysis was conducted to determine factors associated with recent compared to long-term infection. Results Participants were recruited from August 2018 to May 2019 and 184 patient-samples included in this study. The majority were female (108 [59%]) with a median age of 36 years (interquartile range 30–50 years). We found 13 (7.0%) recent infections, while 171 (93.0%) were classified as long-term HIV infections. No conclusive evidence for risk factors of recent infection was found. Conclusions During door-to-door testing among a general population sample in rural Lesotho, 7% of those who were newly diagnosed had acquired HIV in the preceding 6 months. More efforts and research are needed to curb ongoing transmissions in these rural communities.
Additively manufactured Ti6Al4V parts have only seen major application in industries such as the aerospace and medical industries, mainly due to the high cost of production of the feedstock powder. In this article, the feasibility of in situ alloying a powder blend of elemental Ti and an Al-V master alloy to produce the Ti6Al4V alloy through direct metal laser sintering is presented and discussed. In a previous study, single track formation from this powder blend was studied and analyzed to determine the optimum principal process parameters suitable for this powder blend. These process parameters were employed in this study to produce single and double layers where the effects of varied hatch distance and the employment of a rescanning strategy on the surface morphology and alloy homogeneity were investigated. Lastly, in the current study, three-dimensional specimens were produced and analyzed to determine the alloy microstructure, homogeneity, part porosity and mechanical properties. The analyses revealed that a Ti6Al4V alloy with a density of up to 99.9% and corresponding tensile strength and ductility values of up to 942.9 MPa and 17% was produced. Furthermore, a minimum Al evaporation value of 7.2% was recorded. Therefore, in situ alloying can indeed be employed to produce high-quality Ti6Al4V parts from an elemental Ti and an Al-V master alloy powder blend.
Heat treatment of direct metal laser sintering (DMLS) Ti6Al4V (ELI) generates different mechanical properties of the alloy depending on the heat treatment cycle adopted. This is due to the different aspects of the microstructure, such as phase fraction, grain size, texture, and dislocation density, which vary with heat treatment. Other external factors, such as the prevailing level of strain, strain rate, and temperature, also affect the mechanical properties of the material. This paper presents the development of a theoretical model that couples the effects of strain rate, temperature, strain, grain size, and initial dislocation density to describe the flow properties of DMLS Ti6Al4V (ELI). According to the model, higher initial dislocation density results in higher yield stress, low strain hardening, and earlier saturation of flow stress. The model shows that the parabolic shape of the stress-strain curve of the alloy is dictated by the initial dislocation density, which is generally a factor of grain size.
There is an approximately 3% of fresh water available globally for utilization, while the rest of the water is not available for usage, leaving billions of people with less water. Less water availability means that the majority of water consists of pollutants either in ground water or drinking water, which in turn may have a negative impact on the environment and people. Various methods such as plasma technology, flocculation, neutralization, and disinfection have been utilized for wastewater treatment. The wastewater treatment methods have been found to be selective in terms of the removal of other pollutants, as a result, the majority of them are unable to remove pollutants such as antibiotics at a trace level. In order to ensure that there is a complete removal of pollutants from water, there is a need for the development of alternative wastewater treatment methods. The use of solar light by photocatalysis is an alternative method for the degradation of toxic pollutants. Different photocatalysts such as zinc oxide (ZnO), titanium dioxide (TiO2 ), and silver (Ag) have been used in the process of photocatalysis. However, the above photocatalysts were found to have drawbacks such as agglomeration at higher contents and health problems during transportation. To solve the above problem, the nanoparticles were immobilized in various matrices such as polymers and ceramics, with polymers being preferred because of low cost, chemical inertness, and high durability. The current review discusses various methods for the preparation of ZnO and its synergy with other nanoparticles incorporated in various polymer matrices. Because it is known that the preparation method(s) affects the morphology, the morphology and the photocatalytic activity of various ZnO/polymer composites and hybrid systems of ZnO/other nanoparticles/polymer composites are discussed in depth.
This paper ascertained the performance of the evacuated tube solar water heater (SWH) coupled with an auxiliary electric heater with reference to the replaced electric water heater with the same storage tank capacity (200 L) in a building. It also examines the influence of the uptake of the SWHs in the community due to different campaign methods. The study evaluated the performance of a 4 kW electric water heater and a 2 kW input SWH with an auxiliary electric heater, and quantified the annual energy and cost savings. A survey using questionnaires was conducted among 150 residences in Dimbaza based on the house representative’s perceptions to replace their electric water heaters with solar water heaters (based on the monetary saving inscribed on the solar water heaters, the sensitization of the target population on the environmental benefits of the solar water heaters and both the monetary savings and environmental benefits). The findings revealed that by replacing the electric water heater with the solar water heater with an auxiliary electric heater, the annual electricity savings due to hot water heating was 4408.99 kWh and the net present value payback period was 4.32 years. The desire of the household representatives to replace their existing electric water heaters with solar water heaters due to the campaign strategies increased from 75 to 126. This study is capable of providing a mechanism to increase the penetration of solar water heaters and justifying the techno-economic viability of solar water heaters.
The Ministry of Tertiary Institutions of South Africa charged post-secondary institutions to implement measures to achieve the government's social distancing policy. Institutions shifted to remote learning to sustain their core business of teaching and learning. However, there were concerns with the implementation of these measures. For instance, pre-service teachers were seen as ill-equipped and poorly supported during remote learning. This paper aims to contextualise the identity of pre-service economic and management science teachers and reflect on their experiences of curriculum practice during remote learning. Architecture theory was used as the main lens for this study. Furthermore, the goal is to reflect on their adaptation to remote learning as the new normal. Participants’ experiences and factors that affected them are discussed as data collected using the critical participatory action learning and action research (CPALAR) approach as a form of critical education science. Critical discourse analysis was used to arrive at the following broad findings: firstly, higher learning institutions are obligated to create practical learning experiences for pre-service teachers. Secondly, participants were directly affected academically, socially, and psychologically. This paper concludes with the recommendation that hybrid learning as the new normal is the future of teaching and learning and should be embraced.
A ‘just culture’ in a high-risk work environment empowers workers to report unsafe acts because it always seeks to balance safety and accountability. It is a culture of trust and learning that guides management responses to accidents. The advantage of a just culture that is herein called management safety justice (MSJ) is a motivation to deploy it on construction sites. The purpose of the reported study was to measure MSJ in construction to explore ideas about restorative justice that limit unsafe acts. The data were collected from 276 construction professionals from Nigeria and South Africa in an explanatory-sequential mixed methods research. Both countries account for a major size of the gross domestic product (GDP) and construction activities in the region. MSJ was measured using the NOSACQ-50 instrument. With Cronbach Alpha of 0.85, the findings reveal that both countries scored low when assessed on the NOSACQ-50 with grand means of 2.73 (Nigeria) and 2.83 (South Africa). Further, the participants stated that workers who engage in safety deviance were outrightly removed from site suggesting that management may favour penalties as opposed to a just approach. In essence, the results show that the application of MSJ is limited on constructions sites in both countries. The limited MSJ may suggest poor job satisfaction levels and encourage workers to cover accidents and near misses. The study also identified a dearth in the MSJ literature, especially in construction-related studies and recommends a deliberate conversation among scholars until a model, which motivates error reporting in construction is realized.
Antibiotic resistance necessitates the need for continued search for new antimicrobial compounds. In this study, we report the antibacterial activity, cytotoxic, and antioxidant activity of Sarcophyte sanguinea subsp. piriei (Hutch.) B. The extracts were evaluated for antibacterial activity using the agar well diffusion, micro-dilution, minimum bactericidal concentrations (MBC) and lactate dehydrogenase (LDH) release assay. Furthermore, the cytotoxic effects of extracts were determined using MTT assay against Human Embryonic Kidney (HEK293), Human Breast Endocrine Cells (SKBR-3), Human Colorectal Carcinoma Cells (Caco-2) and Human Hepatocellular Carcinoma (HepG2) cells. The extracts were also assessed for antioxidant activity against 2,2-diphenyl-1-picryl hydrazyl (DPPH), 2–2′-Azino-di-[3-ethylbenzthiazoline sulfonate (ABTS), nitric oxide radicals and Fe²⁺ chelating assays. The methanol extract (MeOH) was subjected to GC-TOF-MS analysis. MeOH extract exhibited highest zone of inhibition (ZI) of 15.67 mm against Staphylococcus aureus. The extract further exhibited 67.0% inhibition against Escherichia coli in a lactate dehydrogenase (LDH) membrane damage assay. In the cytotoxicity assay, MeOH and DCM extracts had LC50 value of 237 µg/ml and 221 µg/ml against SKBR-3 cell line respectively. Gas-chromatography time-of-flight mass spectrometry (GC/TOF-MS) analysis of methanol extract indicated the presence of 5-aminoimidazole-4-carboxamide-1-ád-ribofuranosyl 5′-monophosphate (36.827%), 3-O-methyl-d-glucose (36.827%) and phthalic acid, di(oct‑3-yl) ester (8.161%). Even though the investigated plant is suggested to have anticancer activities by traditional healers, the extracts had little inhibition on selected cancerous cell lines. Given the good antibacterial and antioxidant activity of the extracts, the plant may act as an immune booster and prevent infections in immunosuppressed cancer patients. Detected compounds may be influence the observed biological activity of the plant.
Energy demand has exponentially increased in recent times, mainly because of population and economic growth as well as high standards of living in commercial and residential buildings. Conventional power systems have been undergoing great transformation owing to the integration of renewable energy sources (RESs) and demand side management programs. Solar Photovoltaic–Thermal (PV/T) is one of the most growing Renewable Energy Resources (RERs) because of its low carbon emission, high energy efficiency, cost effectiveness, readily available, among other benefits. Several researches have been explored to enhance the performance of different components in the building integrated systems distributed solar energy for tri-generation: heating, cooling and electricity generation. The Photovoltaic–Thermal (PV/T) energy system may be enhanced using various advanced control schemes and cooling technologies. Energy storage systems have shown outstanding benefits by improving the reliability and security of modern power systems. Ice Thermal Energy Storage (ITES) systems have been used for cooling loads, while Heat Storage Water Tank (HSWT) are used for hot water demand. Alternatively, battery banks have been used for storing chemical energy and releasing electricity to the demand side. This reviewed work highlights various components of a solar driven grid-connected PV/T energy system, considering the ITES, HSWT and a battery bank under-price based Demand Response (DR) in terms of the optimal sizing and operational control.
Although traditional electric storage tank water heaters (ESTWHs) are the most frequently used systems in the world, they are known to be among the highest energy consumers, due to their inefficiency in converting electrical energy to thermal energy. These systems have grown increasingly hostile to consumers, as power prices have risen. Therefore, the need to reduce energy consumption of hot water production, while maintaining the users’ thermal comfort level, has led to the development of more energy-efficient technologies. In this paper, a review of renewable energy water heating systems, particularly air-source heat pump water heaters (ASHPWHs), solar water heaters (SWHs) and solar-assisted heat pump water heaters (SAHPWHs), as well as the background literature of the studies on these systems, carried out in South Africa, under the energy management schemes, is presented.
On-site grid-connected hybrid renewable energy systems are extensively used in the mitigation of scheduled grid load shedding in commercial buildings. This paper proposes an optimal operation of grid-connected hybrid PV-battery-Diesel generator (DG) energy system under scheduled grid load shedding for a commercial building. A mathematical model for an optimal operation of a grid-connected PV-Battery-DG energy system that has a potential of mitigating the scheduled load shedding is developed and implemented. The impact assessment of scheduled load shedding on commercial consumers is also assessed on the cost saving as compared to the baseline without load shedding. Results showcase the potential of the proposed grid-connected hybrid PV-Battery-DG to mitigate scheduled grid load shedding in commercial buildings. Scheduled grid load shedding impacts differently on commercial consumers depending on the scheduled time of a day.
Objectives Failures in identification, resuscitation and appropriate referral have been identified as significant contributors to avoidable severity of illness and mortality in South African children. In this study, artificial neural network models were developed to predict a composite outcome of death before discharge from hospital or admission to the PICU. These models were compared to logistic regression and XGBoost models developed on the same data in cross-validation. Design Prospective, analytical cohort study. Setting A single centre tertiary hospital in South Africa providing acute paediatric services. Patients Children, under the age of 13 years presenting to the Paediatric Referral Area for acute consultations. Outcomes Predictive models for a composite outcome of death before discharge from hospital or admission to the PICU. Interventions None. Measurements and main results 765 patients were included in the data set with 116 instances (15.2%) of the study outcome. Models were developed on three sets of features. Two derived from sequential floating feature selection (one inclusive, one parsimonious) and one from the Akaike information criterion to yield 9 models. All developed models demonstrated good discrimination on cross-validation with mean ROC AUCs greater than 0.8 and mean PRC AUCs greater than 0.53. ANN1, developed on the inclusive feature - et demonstrated the best discrimination with a ROC AUC of 0.84 and a PRC AUC of 0.64 Model calibration was variable, with most models demonstrating weak calibration. Decision curve analysis demonstrated that all models were superior to baseline strategies, with ANN1 demonstrating the highest net benefit. Conclusions All models demonstrated satisfactory performance, with the best performing model in cross-validation being an ANN model. Given the good performance of less complex models, however, these models should also be considered, given their advantage in ease of implementation in practice. An internal validation study is now being conducted to further assess performance with a view to external validation.
Laser powder bed fusion (LPBF) has opened the window of in-situ alloying elemental powders for specific engineering and biomedical applications. However, since the LPBF process is non-linear, and the current numerical models are still at the experimental stage it is obligatory to determine the optimum process parameters for each powder composition. The current experimental data described the effects of laser powers and scanning speeds on fused tracks and layers produced using Ti10Mo6Cu powder blend. Fused single tracks were produced at varying scanning speeds and laser powers. The process parameter that falls within the conduction mode threshold was used to produce double layers at varied hatch distances. Layers were rescanned at an offset distance of half the hatch distances. The fused tracks and layers were metallurgically prepared according to the Struers protocol and etched with Kroll's reagent. Optical and scanning electron microscopes were used to measure the width (W), depth of penetration (D), and height (H) of the fused tracks to obtain the data for characterizing the geometry of the fused tracks. Data on the surface quality of the fused layers were extracted with a Surftest SJ-210 portable surface roughness tester, while microhardness test data was extracted using a FM-700 Digital Vickers Microhardness Tester. The data obtained could be used for validating numerical and analytical models, and for predicting fused track profiles. Data that originated from the layers could be used to predict the morphology of layers and the dispersion of elements during in-situ alloying. The methodology applied could be used by other researchers to determine the process parameters for other powder blend compositions and increase the materials database for the LPBF process.
Despite the advances and significant benefits of additive manufacturing globally, Africa and several developing countries are lagging behind due to several adoption barriers. South Africa has nevertheless made significant gains in the area of additive manufacturing over the past three decades. The current study examines the critical success factors that have led to South Africa’s relative success in the field of additive manufacturing by overcoming the barriers. One of such success factors was the demonstration of visionary leadership and commitment to additive manufacturing through huge investments. The building of human capital through education and research in the area of additive manufacturing is another factor. The development of a strong collaboration between industry and research involving both local and international institutions represents another success factor in South Africa’s additive manufacturing growth. Lastly, a positive national culture that drives the adoption of new technologies which is defined by the display of low power distance, high individuality, masculinity, and lower uncertainty avoidance index is another success factor of additive manufacturing success in South Africa.
Background: Forensic radiography is an important component in forensic sciences. There seems to be a lack of recent studies in the literature on the knowledge and training of forensic pathologists and registrars performing forensic radiography at forensic pathology mortuaries in South Africa. Aim: To evaluate the knowledge and training of forensic pathologists (consultants) and registrars performing forensic radiography at a forensic pathology mortuary in the Free State province, South Africa. Setting: A prospective study was conducted at a conveniently selected forensic pathology mortuary located in the Free State province of South Africa. Method: Personnel performing forensic radiography at the selected mortuary were invited to participate in the study. An exploratory quantitative study design was used. The research tool was a self-administered questionnaire comprising open- and closed-ended questions. Four registrars and four consultants (n = 8) completed the questionnaire. Results: Training was only received on computed tomography (n = 1; 12.5%), the C-arm machine (n = 1; 12.5%) and the digital X-ray mobile machine (n = 1; 12.5%) Lodox on corpse positioning (n = 7; 87.5%) and setting of exposure factors (n = 2; 25%). Conclusion: Lack of training of the personnel performing forensic radiography, at the selected mortuary was identified. Training is required in image acquisition protocols, quality control tests of the X-ray machines, setting technical factors and operation of various X-ray machines. Contribution: Training of registered radiation workers who perform forensic radiography in mortuaries is essential to produce high-quality ionising radiation images and ensure their own and other staff members’ safety.
Informed by the Bricolage theory, the authors sought to interrogate the role of religious education in combating school violence in South Africa in the post-pandemic era. While COVID, in many arguments, has been seen as catastrophic to humankind, it has evoked a religious sense among people to enable them to confront vulnerability, which can be harnessed to mitigate school violence. Located in participatory action research, a qualitative approach was used to collect data from twelve participants within the Free State province, where purposive sampling was used. The authors responded to two questions: What are the instigators of school violence? How can religious studies mitigate school violence in South African schools? The paper found that while religious education is underplayed in the South African curriculum, it has an impetus to ignite morality among teachers and learners to address school violence. Based on the paper’s findings, the article argues that despite its shortfalls, religious education remains one of the pillars of enacting the missing ingredient of morality which has made schools unsafe havens for educational stakeholders. In light of this argument, the article recommends reconsidering religious education as a core subject in South Africa from a borderless curriculum angle. Keywords: Bricolage, Religious Studies, School violence, Morality, COVID-19, Sustainable learning and borderless curriculum
Smallholder livestock farmers routinely use existing communication networks as their information sources. This study explored these information sources, the frequency of contacts, and perceived usefulness of livestock health-related information received from these sources. Respondents were randomly selected from two farming districts in the Free State province. Using a mix of descriptive and correlation analyses, it categorized respondents according to their total information scores (TISs) and explored the relationship between their scores and socioeconomic characteristics. Findings show that 65% of farmers scored a high reliance on fellow farmers and extension officials. Mass media sources such as radio and television scored low on perceived usefulness. The correlation coefficients for age (−0.228), farming experience (0.183), extension visits (0.002), and information contacts (0.214) were significant ( p < 0.05). Level of education (0.256), herd size (0.067), and perceived usefulness of information contacts (0.252) were also significant ( p < 0.01). Gender, household size, income, cooperative participation, and access to financial services were not correlated to the TISs of respondents. It was recommended that mass media sources in the area be supported by extension communication specialists to disseminate livestock health-related information.
Unsafe behavior of workers remains a significant cause of accidents, fatalities, and reduced productivity on construction projects. Although a variety of factors that cause such unsafe behaviors among construction workers have been identified, sleep deprivation appears predominant. Hence, the primary objective of this study is to determine the factors that result in sleep deprivation, as well as the relationship between such factors, to curb such unsafe behaviors. Fifteen casual factors influencing sleep deprivation were identified from existing literature. The relationships between these casual factors were established and determined using interpretive structural modeling (ISM). Consequently, ISM was used to establish a five-level hierarchical structure (diagraph) describing the relationships between the casual factors of sleep deprivation. Factors that can directly influence behavior include social influence and actions at the recognition and response stages. In addition to age and sex, root casual factors include educational background and ethnicity. Thus, the results of the analysis conducted in this study indicate that age, gender, and type of worker are root factors that affect sleep deprivation. These factors need to be considered to prevent sleep deprivation-induced accidents in construction sites. Identifying root causal factors culminating in sleep deprivation among workers bears significant implication for the construction industry. In addition to contributing to health and safety in the construction domain, the findings of this study can aid in the development of an appropriate intervention to curb the malaise.
Water shortage in terms of both physical and economic water scarcity is still a major issue globally. The looming climate change threat has increased the adverse threats to water security in different regions. However, policy solutions to water security vary in different geographical regions and at different scales (local, regional, national, etc.). Understanding the successes and challenges of different policy solutions is critical to scaling-up successful policies and addressing water security holistically. This paper aims to explore the effects of implementing policies at different scales in three different case study contexts: 1. two Counties in California in the USA, 2. the City of Cape Town in South Africa and 3. the Country of Bangladesh. These case studies highlight various implemented policies and their effectiveness in each context. We reviewed relevant research papers consisting of peer-reviewed journal articles, conference proceedings and gray literature using a content analysis approach based on keywords such as water scarcity, water shortage, climate change, policies, interventions and solutions. Based on this cross-case analysis, we present key strategies moving forward, including: reallocation of water based on different community and sector needs, the importance of stakeholders engagement and public awareness, and a need to implement both short and long-term management plans. There is no one-size fits all policy solution to water scarcity. Understanding the context, scale, and cultural environment will be a key to future water security-focused interventions and policies.
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1,521 members
Tshepiso Makhafola
  • Department of Health Sciences
Pravin Kendrekar
  • Department of Health Sciences
Sam Mashele
  • Department of Health Sciences
N.J. Joyce Malebo
  • Center for Applied Food Safety Technology (CAFSB)
Muthoni Masinde
  • Department of Information Technology
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20 President Brand Street, 9300, Bloemfontein, Free State, South Africa
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Prof. HJ de Jager (http://www.cut.ac.za/vice-chancellors-office/)
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www.cut.ac.za
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