South African Journal of Science

A journal's dilemma

The extraordinary life of a pioneering museum curator

The mind of South Africa: A review of Nation on the Couch

Interdisciplinary perspectives on the traditional 'big' questions of philosophy

Exploring the potential of scientometrics for the humanities and social sciences: Towards the future

Understanding Higher Education - Critically

Dance as physical exercise for older people

SIGNIFICANCE: • Adequate physical exercise is important for the somatic and mental health of older people. • Dance, as an alternative to structured exercise, could provide both health and social aspects. • The potential to adapt dance style and intensity to accommodate physical limitations makes dancing suitable for many older adults.

Science always makes a difference

The IPCC Assessment Report Six Working Group 1 report and southern Africa: Reasons to take action

Innovative building technologies 4.0: Fast-tracking housing delivery through 3D printing

AI inventorship: The right decision?

Are we there yet? Academies, scientific organisations, and gender

The polyphagous shot hole borer beetle: Current status of a perfect invader in South Africa

The polyphagous shot hole borer (PSHB) beetle is a recent invader in South Africa. Together with its fungal symbiont, Fusarium euwallaceae, it can rapidly kill highly susceptible host plants. Its impact is most profound in urban areas, but it has also been found infesting important forestry, agricultural crop and native species. Since its first detection in 2012, PSHB has spread to all but one province in the country. The beetle-fungus complex has several biological traits that enhance its anthropogenically mediated dispersal, establishment and survival in novel environments - factors that have likely facilitated its rapid spread across the country. We review the history of the PSHB invasion in South Africa, its taxonomic status and the reasons for its rapid spread. We highlight its potential impact and challenges for its management. Finally, we provide an updated distribution map and list of confirmed host plants in South Africa. Of the 130 plant species identified as hosts, 48 of these (19 indigenous and 29 introduced) are reproductive hosts able to maintain breeding PSHB populations. These reproductive hosts may succumb to beetle infestations and act as 'pest-amplifiers'. The economic impact on urban forests, plantation forestry and agricultural crops may be severe, but the ecological impact of PSHB invasion in native ecosystems should not be underestimated.SIGNIFICANCE: • We provide an updated host list and distribution map for South Africa of the globally significant tree pest, the polyphagous shot hole borer (PSHB, Euwallacea fornicatus). The South African PSHB invasion represents the largest outbreak of this pest in its global invaded range. PSHB was confirmed to infest 130 plant species in urban, agricultural, and native ecosystems in South Africa, including 44 previously unreported hosts. Impact in South Africa is in its infancy but will likely be substantial to local economies and ecosystems. Mitigation has proven difficult, but numerous research projects have been initiated throughout the country.

**Antibiotic resistance profiles of Staphylococcus spp. from white button mushrooms and handlers**

The presence of Staphylococcus spp. has increasingly been reported in food products and poses a public health threat. The aim of this study was to determine the diversity of Staphylococcus spp. and the antibiotic resistance profiles of isolates obtained from freshly harvested and packed ready-to-eat mushrooms (n=432) and handlers' hands (n=150). A total of 56 Staphylococcus isolates [46.4% (n=26) from hands and 53.6% (n=30) from mushrooms] were recovered belonging to 10 species. Staphylococcus succinus isolates (n=21) were the most prevalent, of which 52.4% came from mushrooms and 47.6% from hands. This was followed by S. equorum isolates [n=12; 91.7% (n=11) from mushrooms and 8.3% (n=1) from hands] and S. saprophyticus [n=9; 66.7% (n=6) from mushrooms and 33.3% (n=3) from hands]. Six isolates that were characterised as multidrug resistant were isolated from hands of handlers. Most (83.9%; n=47) of the 56 isolates were resistant to penicillin [53.2% (n=25) from mushrooms and 46.8% (n=22) from hands] and 14.3% (n=8) were resistant to cephalosporin classes [25% (/=2) from mushrooms and 75% (n=6) from hands], both of which are used to treat staphylococcal infections. Antibiotic resistance genes blaZ [25.0% (n=14) of all isolates of which 71.4% (n=10) were from hands and 28.57% (n=4) from mushrooms], tetL and tetK [both 1.8% (n=1) from hands], mecA [5.4% (n=3) from hands] and ermA [1.8% (n=1) from mushrooms] were detected from the 56 isolates. Only two (25.0%) of the eight methicillin-resistant staphylococci harboured the mecA gene, while only 11 (23%) of the 47 penicillin-resistant isolates harboured the blaZ gene [36.4% (n=4) from mushrooms and 63.6% (n=7) from hands]. Our results demonstrate that food handlers and harvested and packed ready-to-eat mushrooms could be a source of diverse Staphylococcus spp. that exhibit antimicrobial resistance. Clinically relevant S. aureus was only detected on one handler's hand; however, the isolate was not multidrug resistant. The presence of diverse Staphylococcus spp. on mushrooms and the hands of handlers is a potential public health concern due to their potential to cause opportunistic infections.SIGNIFICANCE: • This study is the first to describe the antibiotic resistance profiles and antibiotic gene presence of Staphylococcus spp. isolated from fresh mushrooms and hands of pickers and packers. Mushrooms and handlers in this study were demonstrated to be possible routes of transmission of Staphylococcus spp. that are antibiotic resistant and which harbour antibiotic resistance genes, presenting a possible public health hazard.

Renewable energy potential of anaerobic mono-and co-digestion of chicken manure, goat manure, potato peels and maize pap in South Africa

The energy sector is an essential part of a country's economy - it drives innovation and advances industrialisation. Coal is the primary source of energy in South Africa. Coal contributes 95% of energy production; coal-fired power also contributes to greenhouse gas emissions, and is thus a hazard to human health and the environment. This calls for an energy mix that is renewable, sustainable, and affordable and that is carbon neutral (climate action). We investigated the potential of anaerobic mono-and co-digestion of goat manure, chicken manure, potato peels, maize pap, and cow manure inoculum for mesophilic recovery of renewable energy using the biomethane potential test. The substrates were characterised through proximate and ultimate analyses to determine the composition preferable for mono- and co-digestion. The key considerations in the determination of both the yield and production rate of methane from digestion of biomass are the substrate composition and characterisation. A high percentage of volatile solids favoured optimum biomethane production as highly volatile components provide microbes with balanced nutrients that enhance metabolic processes to produce biomethane. The mono-digestion process produced lower biomethane than did co-digestion. Higher production of biomethane by co-digestion was due to the balance of the micronutrients and macronutrients that favoured microbial metabolism and regulation of pH.SIGNIFICANCE: • The results highlight the need for appropriate techniques in combining energy and waste management. Biogas could provide solutions for some of South Africa's energy necessities, particularly in rural areas that have abundant biogas substrates in the form of waste from goats and chickens, as well as from kitchen waste.

Photodegradation and kinetics of edible oil refinery wastewater using titanium dioxide

Edible oil refinery wastewater (EORW) is one source of environmental pollution in Nigeria. The treatment of EORW before discharge into the environment remains a significant challenge in the edible oil refinery industries. This research was aimed at photocatalytic treatment of EORW using a batch photocatalytic reactor with titanium dioxide photocatalyst. We investigated the physicochemical parameters: chemical oxygen demand (COD), biological oxygen demand (BOD5), oil and grease, phenol, chloride (CI), total suspended solids, sulfate (S0(4)2-), and phosphate (P0(4)3-) using American Public Health Association methods. The results showed that the reduction efficiency of the treated EORW with TiO2 catalyst ranged between 65.8% (P0(4)3-) and 87.0% (COD), and the improvement in efficiency was 54.1% (pH) and 60.8% dissolved oxygen. However, the results showed no significant difference (p<0.05) in the control treatment without catalyst. The biodegradability of EORW increased from 0.196 to 0.32. It was observed that the optimum values were an initial EORW concentration of 100 mL/L, irradiation time of 90min, catalyst dose of 1.25 g/L, and an agitation speed of 900 rpm. The kinetics of the photodegradation process was well described by the pseudo-first-order equation (R²>0.96) and pseudo-second-order equation (R²>0.98). The intra-particle diffusion model fairly represented the diffusion mechanism with an R² value of 0.806. The treated EORW met the most acceptable water quality standards for discharged effluent according to the maximum permissible limits of the Nigerian National Environmental Standards and Regulations Enforcement Agency.SIGNIFICANCE: Photocatalytic treatment of EORW gave negligible results in the absence of a photocatalyst. The photocatalytic degradation of EORW improved its biodegradability. Photocatalytic treatment of EORW significantly reduced the pollutants in the wastewater. The pseudo-first-order equation (R²>0.96) and pseudo-second-order equation (R²>0.98) well described the photodegradation process of EORW.

Evaluation of the binding and disintegrating properties of gum obtained from the stem bark of Cinnamomum zeylanicum

Excipients are the various ingredients, apart from the active pharmaceutical ingredients, which are added to pharmaceutical formulations. Excipients obtained from natural sources are preferred over those from synthetic sources because they are cheap, biocompatible and readily available. Gums are made up of carbohydrate units which are linked by glycosidic bonds. This study was aimed at evaluating the potential binding and disintegrating properties of gum obtained from the bark of Cinnamomum zeylanicum, which was obtained from Effiduase in the Ashanti region of Ghana. The gum was extracted using 96% ethanol and the moisture content, Fourier transform infrared spectroscopy spectra, water holding capacity, swelling index and flow properties of the gum were determined. The gum was used to formulate tablets at different concentrations (10% w/v, 15% w/v and 20% w/v) as binder with acacia as the standard. The gum was also used to formulate tablets at different concentrations (5% w/v, 7.5% w/v and 10% w/v) as disintegrant with starch as the standard. Quality control tests were then conducted on all formulated tablets. The gum exhibited good flow and physicochemical properties. All formulated tablets passed the uniformity of weight test, friability test, disintegration test, hardness test, uniformity of dimensions test and drug content. All batches of tablets, except Batch 7, passed the dissolution test. Based on the study carried out, C. zeylanicum gum can be used as an alternative excipient to acacia and starch as a binder and a disintegrant, respectively.SIGNIFICANCE: • A natural polysaccharide (gum) from the bark of Cinnamomum zeylanicum tree can be harnessed and commodified as a pharmaceutical excipient (binder and disintegrant) in the production of immediate release tablets.

A validated method for the analysis and profiling of 'nyaope' using gas chromatography - mass spectrometry

Nyaope, a Tswana word for a mixture or 'mish-mash', describes a drug cocktail consisting of heroin, cannabis, and on occasion other controlled substances and warfarin. It is highly addictive with extremely unpleasant side effects caused by withdrawal from the drug. It is a problem drug especially in townships in South Africa. However, its prevalence in neighbouring southern African states and further afield is not yet known. There is currently no validated method for the analysis and comparison of nyaope. We describe a validated method for the gas chromatography - mass spectrometry analysis of nyaope so that within-batch and between-batch comparisons of nyaope can successfully be made for the first time. The validated method managed an accuracy within the range 80-120%, the precision was less than 20% for all analytes and managed linearity with R²>0.99. The detection limits for diamorphine, efavirenz, nevirapine and Δ9-tetrahydrocannabinol were 14.2, 18.6, 18.7 and 9.94 pg on column, respectively, and the limits of quantitation were 43.1, 56.3, 56.6 and 30.1 pg on column, respectively. The simulated and casework samples were successfully discriminated into original batches using the identified nyaope components, the unsupervised chemometric methods principal component analysis and hierarchical clustering, as well as chromatographic profiles.SIGNIFICANCE: • A validated method for the analysis and comparison of nyaope allows for data exchange between law enforcement agencies in South Africa and, provided the appropriate quality control measures are in place, between South Africa, neighbouring states and countries further afield. Additionally, public health measures can be put in place now that it is possible to use a validated method to determine the contents of nyaope.

Life cycle assessment of single-use and reusable plastic bottles in the city of Johannesburg

Polyethylene terephthalate (PET) bottles of water have experienced huge growth in demand and sales in South Africa. This expansion in use creates challenges as well as opportunities for managing the life cycle impact. The properties that make PET desirable for fluid-containing bottles have also made it highly resistant to environmental biodegradation. Reusable plastic bottles are now marketed as a solution to reduce the impact of single-use plastic bottles. We assessed the life cycle impact of single-use PET bottles and an alternative, reusable PET bottle based on consumption patterns in South Africa and the material flow and supply chain in the urban environment. This robust consideration of local conditions is important in evaluating the life cycle impact. In an examination of 13 impact categories, the reusable PET bottle had lower impact than the single-use bottle in all the impact categories examined. The mass of PET bottle material required to deliver the water needs at any given time is a dominant factor on the environmental burden. Extending the life of reusable bottles and designing lighter weight bottles would reduce their life cycle impact. Information obtained in evaluating alternatives to plastic water bottles can be valuable for providing a foundation assessment for policymakers and plastic bottle manufacturers to make informed choices and to focus on improvements in life cycle impact.SIGNIFICANCE: • The significant impact of the production phase in the life cycle of both single-use and reusable PET bottles confirms the need to design a much more lightweight bottle to reduce the mass of materials used in production. • Another key consideration was the long transportation distance covered during the production phase, and the negative impact of current vehicular emissions. Municipalities and waste collectors should consider the use of low-carbon transport. • This study highlights the value of extending the life of plastic bottles, as well as recycling for material recovery, remanufacturing and repurposing these bottles within the City. • The use of fewer, larger single-use bottles compared with a greater number of smaller single-use bottles is discussed.

Determination of alcohols in hand sanitisers: Are off-the-shelf hand sanitisers what they claim to be?

Transmission of SARS-CoV-2 - the causative agent of COVID-19 - can be prevented through non-pharmaceutical interventions such as observing proper hand hygiene using alcohol-based hand rubs/sanitisers (ABHRs) as recommended by the WHO and local health authorities. However, this recommendation has led to high demand for ABHRs and proliferation of sub-standard products, which do not contain the recommended amount of alcohol. Fifty products of different origins and formulations obtained off-the-shelf and in public places in and around Pretoria (South Africa) were analysed for their alcohol content using gas chromatography. Ethanol was the most common alcohol used in the products, followed by isopropanol. Only 21 (42%) of the products analysed contained at least 70% alcohol; of these only 14 (28%) met the WHO recommended 80±5% alcohol content to have a virucidal effect on SARS-CoV-2. Of the 41 commercial off-the-shelf products analysed, 27 (66%) contained less than 70% alcohol in comparison to 13% of homemade products. Only 18% of gel products contained 70% alcohol, compared with 47% for liquid-based products. Most of the products did not contain the appropriate or correct declaration as recommended by the South African National Standards (SANS 289 and 490). The proliferation of substandard ABHRs is of great public health concern and calls for stricter regulations and enforcement in order to protect consumers, their rights and well-being during and post the COVID-19 pandemic period. However, in the interim, formulation of ABHRs using the WHO guidelines should be mandatory, as such formulations, when made correctly, do have the required virucidal effect against SARS-CoV-2.SIGNIFICANCE: • Commercial, off-the-shelf and public hand sanitisers were analysed to determine whether they contained enough alcohol to be efficacious virucides as recommended by the WHO. • The majority of the products analysed were substandard, did not contain the recommended amount of alcohols and were not labelled correctly according to local and international standards. • Homemade products conformed to a greater degree to the WHO standards for alcohol-based hand sanitisers. It is evident from these results that there is a need to monitor the manufacture of off-the-shelf products to ensure compliance and to assure consumers that products offer the required protection against SARS-CoV-2.

Developing an environmental research platform in the Karoo at the Square Kilometre Array

A part of the Square Kilometre Array (SKA) will be constructed in the northern Karoo of South Africa on approximately 135 000 ha of land. This land is formerly privately owned rangelands (farms) that were purchased by the South African National Research Foundation (NRF), on which the South African Radio Astronomy Observatory, as part of the global SKA project, will erect the SKA infrastructure. Additionally, a long-term environmental research programme will be established to investigate various dryland ecosystem components at a landscape scale. Livestock has been removed from the farms, and the area is now managed by the South African National Parks (SANParks) as the Meerkat National Park. The land-use and land cover changes present an unprecedented opportunity to study ecosystem dynamics. The property will be established as an NRF science park, incorporating an SKA research platform for radio astronomy and an environmental research platform of the South African Environmental Observation Network, with additional environmental research conducted by SANParks and their collaborators. We briefly describe current knowledge of the area's environment, and report on past and contemporary changes in this part of the Karoo. We present a conceptual model for the larger landscape which considers possible future land-use scenarios, the projected trajectories of change under these scenarios, and factors influencing these trajectories. These deliberations represent the foundation for future research in this landscape and the development of an environmental observation research platform in the Karoo at SKA.SIGNIFICANCE: • We summarise an extensive environmental baseline report on the SKA property and surrounding areas. • Withdrawal of livestock and other changes - such as clearing of alien invasive plants, reduced predator control and reduction in water-point maintenance - are expected to bring about changes in ecological processes and plant and animal communities. • We present a conceptual model of scenarios to test possible future trajectories as a first step towards an earth system science research platform in the NRF science park.

Food security and related health risk among adults in the Limpopo Province of South Africa

Food insecurity, obesity and hypertension remain major public health issues related to nutrition in South Africa. The purpose of this study was to determine household food security and the health risk of the adult population in the Limpopo Province using cross-sectional designs. A stratified random sampling method was used to recruit adults aged 18 to 65 years in the Limpopo Province of South Africa. Data were collected using a validated, structured questionnaire. All data were analysed using SPSS version 25.0. The study included 640 participants with an average age of 36.2±17.6 years and a household size of five persons; 74.5% of participants fell in the low monthly income bracket (

Temperature and relative humidity trends in the northernmost region of South Africa, 1950-2016

The northernmost Limpopo Province is located in one of the warmest regions of South Africa, where the agricultural sector is prone to heat stress. The aim of this study was to explore air temperature and relative humidity trends for the region, which have implications for agricultural adaptation and management (amongst other sectors). In particular, we investigated seasonal, annual and decadal scale air temperature and relative humidity changes for the period 1950-2016. Positive temperature trends were recorded for this period, averaging +0.02 °C/year, with the strongest changes observed in mean maximum summer temperatures (+0.03 °C/year). Interannual temperature variability also increased over time, especially for the period 2010-2016, which presents probability densities of <50% for minimum temperatures. Positive relative humidity trends (+0.06%/year) were also recorded for the period 19802016, but proved to be the least predictable weather parameter, with probability densities of <0.5% across seasons for the study period. Considering the substantial interannual variability in temperature and relative humidity, there is clear increased risk for the agricultural sector, particularly for small-scale farmers who generally have limited capacity to adapt. Climate science focusing on the southern African region should continue to establish the impact of climate change and variability on specific small-scale farming systems and enterprises, with recommendations for strategic adaptation based on up-to-date evidence.SIGNIFICANCE: • Heat indices have increased, and variability in temperature and relative humidity has substantially increased over recent decades. • Changes in air temperature and relative humidity have direct and/or indirect negative effects on sectors such as agriculture, leading to reduced productivity. • The small-scale farming sector, which contributes significantly to national food security in developing countries, is the production system most exposed and vulnerable to observed changes/extremes in temperature and relative humidity. • There is an urgent need to build capacity of small-scale farmers for appropriate adaptation to observed changes in climate based on up-to-date evidence.

Self-esteem and antiretroviral therapy adherence among young people living with HIV: An exploratory serial mediation analysis

Capitalising further on the benefits of antiretroviral therapy (ART) for individual treatment requires an improved understanding of the psychological processes that may affect optimal ART adherence among people living with HIV. We examined internalised HIV/AIDS-related stigma and body appreciation as mediators of the association between self-esteem and ART adherence among young people living with HIV (YPLHIV). A sample of 76 YPLHIV (Mage = 19.36, s.d.age = 2.56; male 56.58%) residing in an HIV hyperendemic region of South Africa completed self-report measures of self-esteem, internalised HIV/AIDS-related stigma, body appreciation, and ART adherence. Path-analytic mediation modelling was performed to test for direct and indirect effects linking self-esteem with ART adherence. Results of serial mediation analyses indicated that self-esteem and ART adherence were indirectly associated through a two-step path of internalised HIV/AIDS-related stigma and then body appreciation, as well as a one-step path through internalised HIV/AIDS-related stigma. The results provide preliminary support for internalised HIV/AIDS-related stigma and body appreciation as mechanisms underlying the association between self-esteem and ART adherence. Implications of the findings for promoting ART adherence among YPLHIV are discussed.SIGNIFICANCE: • Self-esteem and ART adherence were indirectly related through internalised HIV/AIDS-related stigma followed by body appreciation. • Outcomes of intervention initiatives designed to promote ART adherence among young people living with HIV may be further improved by integrating components that target internalised HIV/AIDS-related stigma and body appreciation.

Mechanical loading of primate fingers on vertical rock surfaces

Mechanical loading of finger bones (phalanges) can induce angular curvature, which benefits arboreal primates by dissipating forces and economising the recruitment of muscles during climbing. The recent discovery of extremely curved phalanges in a hominin, Homo naledi, is puzzling, for it suggests life in an arboreal milieu, or, alternatively, habitual climbing on vertical rock surfaces. The importance of climbing rock walls is attested by several populations of baboons, one of which uses a 7-m vertical surface to enter and exit Dronkvlei Cave, De Hoop Nature Reserve, South Africa. This rock surface is an attractive model for estimating the probability of extreme mechanical loading on the phalanges of rock-climbing primates. Here we use three-dimensional photogrammetry to show that 82-91% of the climbable surface would generate high forces on the flexor tendon pulley system and severely load the phalanges of baboons and H. naledi. If such proportions are representative of vertical rock surfaces elsewhere, it may be sufficient to induce stress-mitigating curvature in the phalanges of primates.SIGNIFICANCE: • We present the first three-dimensional photogrammetric analysis of a vertical rock surface climbed by a non-human primate, the chacma baboon (Papio ursinus). • Our results show that a large proportion of a vertical rock wall would compel crimp and slope hand positions during climbing - grips that could explain the extraordinary phalangeal curvature expressed by a Middle Pleistocene hominin, Homo naledi.

An African violin - The feasibility of using indigenous wood from southern Africa as tonewood

The wood used to make musical instruments needs to have particular properties. Depending on its function, such as a soundboard for string instruments or the body of a wind instrument, different properties are desirable to obtain the best musical quality. Several different classification schemes exist that correlate physical and mechanical properties of wood to define desirable ranges for tonewoods, and to allow suitable wood species to be chosen. The physical and mechanical properties of various wood species indigenous to southern Africa were characterised and then assessed in terms of their suitability for violin construction using these classification schemes. The results of this analysis show that the most suitable of the wood species assessed are yellowwood and sapele. These were subsequently used by a professional luthier to build an 'African' violin. The sound quality of this instrument was determined subjectively through performances to an audience and more objectively via spectral analysis of audio recordings. This analysis shows clear differences in the relative magnitude of the harmonics between the violin made from indigenous wood and an instrument made with conventional wood species. Despite the differences, yellowwood and sapele were found to be suitable tonewoods, resulting in an instrument with a unique sound.SIGNIFICANCE: • Good quality violins are always made from spruce and maple wood, which have to be imported to South Africa - often at high cost. However, the growth conditions of most southern African wood species should make them suitable tonewoods. We showed that several species are suitable to be used as tonewoods and that the sound produced with such a violin is - although somewhat different - of high quality.