Career Management for Early Career Scientists in Developing Countries--A South African Experience

This paper discusses career development and options for growth for young scientists in developing countries. We also identify and address some of the common challenges early career scientists face, and apply key principles learned from years of research and experience in the South African context as a basis for our discussion. Early career scientists are more likely to succeed in their career if they understand from the start what they need to do in order to grow to the next level and ultimately to the pinnacle of their careers. Strategically, planning one’s individual career development is critical to success in the science environment as is the case in any other discipline or domain. The development of early career scientists through their career ladder is determined by a number of factors, many of which are within the control of early career scientists. These factors include qualifications, publication track record, attracting research funding, contribution to student training and staff development, leadership in science, and research impact. The contribution of this basket of measures to development of a career in science is critical for development to certain milestones in one’s career. One of the most critical transitions many research scientists have to make is the move from specialist to manager. Expedient promotion of early career scientists to senior management roles without an adequate track record, experience or proper training can be frustrating for both the manager and those under his/her management responsibility. Regardless of the career path one chooses, a solid foundation in research with a good track record of research outputs, funding and the impact of one’s research are crucial to one’s development along either the researcher career ladder or research management career path

A Fuzzy – Based Methodology for Aggregative Waste Minimization in the Wine Industry

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Evaluation of apical and molecular effects of algae Pseudokirchneriella subcapitata to cerium oxide nanoparticles

SUPPLEMENTARY MATERIALS: TABLE S1: The composition of 10% BG-11 medium; FIGURE S1: Size characterization of nCeO2 (a) TEM images [36], (b) size distribution; FIGURE S2: Algal growth of P. subcapitata at different concentrations of K2Cr2O7: FIGURE S3: in situ nCeO2 concentration (particles/mL) characterization examined using Nanoparticle Tracking Analysis [92].Cerium oxide engineered nanoparticles (nCeO2) are widely used in various applications and are, also, increasingly being detected in different environmental matrixes. However, their impacts on the aquatic environment remain poorly quantified. Hence, there is a need to investigate their effects on non-target aquatic organisms. Here, we evaluated the cytotoxic and genotoxic effects of <25 nm uncoated-nCeO2 on algae Pseudokirchneriella subcapitata. Apical (growth and chlorophyll a (Chl a) content) and genotoxic effects were investigated at 62.5–1000 g/L after 72 and 168 h. Results demonstrated that nCeO2 induced significant growth inhibition after 72 h and promotion post 96–168 h. Conversely, nCeO2 induced enhanced Chl a content post 72 h, but no significant changes were observed between nCeO2–exposed and control samples after 168 h. Hence, the results indicate P. subcapitata photosynthetic system recovery ability to nCeO2 effects under chronic-exposure conditions. RAPD-PCR profiles showed the appearance and/or disappearance of normal bands relative to controls; indicative of DNA damage and/or DNA mutation. Unlike cell recovery observed post 96 h, DNA damage persisted over 168 h. Thus, sub-lethal nCeO2-induced toxicological effects may pose a more serious threat to algae than at present anticipated.The South African National Research Foundation—Department of Science and Technology Professional Development Programme Doctoral Grant, the Council for Scientific and Industrial Research (CSIR), South Africa and the Water Research Commission (WRC).https://www.mdpi.com/journal/toxicsam2023Chemical EngineeringNon

Modelling ecological risks of antiretroviral drugs in the environment

APPENDIX A. SUPPLEMENTARY DATA : Supplementary data to this article can be found online at https://DOI.org/10.1016/j.enceco.2023.06.001.The success of the antiretroviral therapy (ART) programme to manage HIV/AIDS in Sub-Saharan Africa (SSA) has inadvertently led to the release of antiretroviral (ARVs) into the environment. Consequently, ARVs have been detected in different countries across the globe, with the highest measured environmental concentrations in the SSA countries. Herein, we quantified ecological risks of ten regimen ARVs (six and four in first and second regimes, respectively) into environmental matrices in four spatial regions in Eswatini, namely: Manzini, Hhohho, Lubombo, and Shiselweni. Ecological risks (expressed as risk quotient (RQ)) were determined for different geographical regions by comparing the predicted environmental concentrations (PECs) to the predicted no effect concentrations (PNECs). PNECs were derived from ecotoxicological data generated using the Ecological Structure Activity Relationships (ECOSAR) model. PECs of ARVs in surfacewater in the Lubombo and Shiselweni regions were three-fold higher compared to those of the Manzini and Hhohho regions with RQs of three ARVs exceeding 10 (RQ > 10) to three taxa (fish, daphnia, and algae). ARVs of concern to the three taxa were ranked in descending order based on both acute and chronic toxicity based on RQ values as efavirenz (EFV) > lopinavir (LPV) > ritonavir (RTV) (all with RQs > 10). Two second regime ARV drugs (RTV and LPV) posed the highest risks to aquatic taxa though they had the least PECs, but were highly toxic with PNECs <1 μg/L. Due to dearth of toxicity data for ARVs on bacteria, their risks in wastewater (with the exception of TDF) could not be established. Results of this study are the first to quantify risks of ARVs in the environment using a modelling approach. The developed model can therefore serve as a first-tier screening tool. In addition, the results raise the need to examine the likelihood of antiviral resistance of ARVs linked to their high environmental concentrations.The Water Research Commission (South Africa).http://www.keaipublishing.com/en/journals/environmental-chemistry-and-ecotoxicology/am2024Chemical EngineeringSDG-03:Good heatlh and well-beingSDG-11:Sustainable cities and communitie

Exposure media and nanoparticle size influence on the fate, bioaccumulation, and toxicity of silver nanoparticles to higher plant Salvinia minima

Silver nanoparticles (AgNPs) are favoured antibacterial agents in nano-enabled products and can be released into water resources where they potentially elicit adverse effects. Herein, interactions of 10 and 40 nm AgNPs (10-AgNPs and 40-AgNPs) with aquatic higher plant Salvinia minima at 600 g/L in moderately hard water (MHW), MHW of raised calcium (Ca2+), and MHW containing natural organic matter (NOM) were examined. The exposure media variants altered the AgNPs’ surface properties, causing size-dependent agglomeration. The bio-accessibility in the ascending order was: NOM <MHW< Ca2+, was higher in plants exposed to 10-AgNPs, and across all exposures, accumulation was higher in roots compared to fronds. The AgNPs reduced plant growth and the production of chlorophyll pigments a and b; the toxic effects were influenced by exposure media chemistry, and the smaller 10-AgNPs were commonly the most toxic relative to 40-AgNPs. The toxicity pattern was linked to the averagely higher dissolution of 10-AgNPs compared to the larger counterparts. The scanning electron microscopy and X-ray fluorescence analytical techniques were found limited in examining the interaction of the plants with AgNPs at the low exposure concentration used in this study, thus challenging their applicability considering the even lower predicted environmental concentrations AgNPs.SUPPORTING INFORMATION: FIGURE S1: Ag NPs size obtained before testing for 10-Ag NPs with (a) TEM and (b) NTA, and 40-nAg NPs with (c) TEM and (d) NTA. Red bars denote the standard error. Inserts in (c) and (d) illustrate relative Ag NPs size intensities, FIGURE S2: The detected elemental analysis for samples exposed to 10-Ag NPs in MWH, Ca, and NOM (top row) and to 40-Ag NPs in MWH, Ca, and NOM (bottom row), FIGURE S3: PCA plots illustrating the association of Ag accumulation (accu) to the Ag NPs size (size), dissolution (diss), and Ag NPs concentration (conc) p for 10-Ag NPs and 40-Ag NPs under different water chemistries (MHW, NOM, and Ca2+), FIGURE S4: Quantification of chlorophyll pigments Chla, Chlb and their ratios in S. minima after exposure to 10- and 40-AgNPs for 48 h. Bars denote standard error (n = 3). Differing symbols on top of error bars indicate statistical difference within a specific photosynthetic parameter. Turkey Kramer HSD, p < 0.05, TABLE S1: The Hoagland’s Medium basal salt recipe used in this study, TABLE S2: freeze dryer settings used in the experimental setup, TABLE S3: The achieved recovery rates for Ag obtained from analysis with ICP-MS, TABLE S4: Comparison of whole plant Ag accumulation ( g/mg dry weight) between 10-Ag NPs and 40-Ag NPs under different water chemistries. In brackets are standard deviations, where n = 3. Student’s t-test, p < 0.05, TABLE S5: Percentage growth reduction relative to respective controls, TABLE S6: Results of AgNPs sizes and concentrations under variant exposure media. The 48 h average particle size were obtained with DLS, modal particle size obtained using NTA over 48 h, and NTA was employed to determine particle concentration over 48 h. The given values are the mean standard error (n = 3). Differing symbols indicate statistical difference (p < 0.05) within a specific AgNPs’ size.The UNESCO Keizo Obuchi Fellowship; the Department of Science and Technology Project on Nano-technology HSE Program, South Africa and the University of Pretoria.https://www.mdpi.com/journal/moleculesam2022Chemical Engineerin

Interactions of coated-gold engineered nanoparticles with aquatic higher plant Salvinia minima baker

The study investigated the interactions of coated-gold engineered nanoparticles (nAu) with the aquatic higher plant Salvinia minima Baker in 2,7, and 14 d. Herein, the nAu concentration of 1000 g/L was used; as in lower concentrations, analytical limitations persisted but >1000 g/L were deemed too high and unlikely to be present in the environment. Exposure of S. minima to 1000 g/L of citrate (cit)- and branched polyethyleneimine (BPEI)-coated nAu (5, 20, and 40 nm) in 10% Hoagland’s medium (10 HM) had marginal effect on biomass and growth rate irrespective of nAu size, coating type, or exposure duration. Further, results demonstrated that nAu were adsorbed on the plants’ roots irrespective of their size or coating variant; however, no evidence of internalization was apparent, and this was attributed to high agglomeration of nAu in 10 HM. Hence, adsorption was concluded as the basic mechanism of nAu accumulation by S. minima. Overall, the long-term exposure of S. minima to nAu did not inhibit plant biomass and growth rate but agglomerates on plant roots may block cell wall pores, and, in turn, alter uptake of essential macronutrients in plants, thus potentially affecting the overall ecological function.Supplementary Materials: Equation (S1): Calculation of ζ potentials using Smoluchowski equation, Equation (S2): Calculation of ionic strength (IS) of the exposure medium, Figure S1: TEM images of nAu (a) 5 nm-Cit, (b) 20 nm-Cit, (c) 40 nm-Cit, (d) 5 nm-BPEI, (e) 20 nm-BPEI, (f) and 40 nm-BPEI, Table S1: Composition of Hoagland’s medium, Table S2: Mean sizes (nm) of nAu obtained using TEM, Figure S2: Particle size distribution of nAu at 1000 µg/L in 10% Hoagland’s medium measured using Dynamic Light Scattering technique (a) 5 nm Cit-nAu, (b) 20 nm Cit-nAu, (c) 40 nm Cit-nAu, (d) 5 nm BPEI-nAu, (e) 20 nm BPEI-nAu, and (f) 40 nm BPEI-nAu, Figure S3: Hydrodynamic diameters of nAu in de-ionized water and 10% Hoagland’s medium tracked using Dynamic Light Scattering technique over 48 h; (a) 5 nm Cit-nAu, (b) 20 nm Cit-nAu, (c) 40 nm Cit-nAu, (d) 5 nm BPEI-nAu, (e) 20 nm BPEI-nAu, and (f) 40 nm BPEI-nAu, Figure S4: Zeta potentials of nAu in de-ionized water and 10% Hoagland’s medium obtained using Dynamic Light Scattering technique over 48 h; (a) 5 nm Cit-nAu, (b) 20 nm Cit-nAu, (c) 40 nm Cit-nAu, (d) 5 nm BPEI-nAu, (e) 20 nm BPEI-nAu, and (f) 40 nm BPEI-nAu, Figure S5: UV-vis spectrum of nAu in de-ionized water as a function of time; (a) 5 nm Cit-nAu, (b) 20 nm Cit-nAu, (c) 40 nm Cit-nAu, (d) 5 nm BPEI-nAu, (e) 20 nm BPEI-nAu, and (f) 40 nm BPEI-nAu, Figure S6: in situ nAu concentration (particles/mL) examined using Nanoparticle Tracking Analysis (NTA), Figure S7: TEM-EDX spectra confirming the absence of nAu internalization on plant roots: (a) control, (b) 5 nm cit-nAu, (c) 20 nm-cit nAu, (d) 40 nm cit-nAu, (e) 5 nm BPEI-nAu, (f) 20 nm BPEI-nAu, and (g) 40 nm BPEI.The South African National Research Foundation and Department of Science and Technology Professional Development Programme Doctoral Scholarship, the Council for Scientific and Industrial Research and the University of Pretoria.https://www.mdpi.com/journal/nanomaterialsam2022Chemical Engineerin

Proteomic evaluation of nanotoxicity in aquatic organisms : a review

The alteration of organisms protein functions by engineered nanoparticles (ENPs) is dependent on the complex interplay between their inherent physicochemical properties (e.g., size, surface coating, shape) and environmental conditions (e.g., pH, organic matter). To date, there is increasing interest on the use of ‘omics’ approaches, such as proteomics, genomics, and others, to study ENPs-biomolecules interactions in aquatic organisms. However, although proteomics has recently been applied to investigate effects of ENPs and associated mechanisms in aquatic organisms, its use remain limited. Herein, proteomics techniques widely applied to investigate ENPs–protein interactions in aquatic organisms are reviewed. Data demonstrates that 2DE and mass spectrometry and/or their combination, thereof, are the most suitable techniques to elucidate ENPs–protein interactions. Furthermore, current status on ENPs and protein interactions, and possible mechanisms of nanotoxicity with emphasis on those that exert influence at protein expression levels, and key influencing factors on ENPs–proteins interactions are outlined. Most reported studies were done using synthetic media and essay protocols and had wide variability (not standardized); this may consequently limit data application in actual environmental systems. Therefore, there is a need for studies using realistic environmental concentrations of ENPs, and actual environmental matrixes (e.g., surface water) to aid better model development of ENPs–proteins interactions in aquatic systems.The Botswana International University of Science and Technology, the University of Pretoria and Water Research Commission.http://www.proteomics-journal.comhj2023Chemical Engineerin

Cytotoxicity and genotoxicity of coated-gold nanoparticles on freshwater algae Pseudokirchneriella subcapitata

Gold engineered nanoparticles (nAu) are increasingly detected in ecosystems, and this raises the need to establish their potential effects on aquatic organisms. Herein, cytotoxic and genotoxic effects of branched polyethylenimine (BPEI)- and citrate (cit)-coated nAu (5, 20, and 40 nm) on algae Pseudokirchneriella subcapitata were evaluated. The apical biological endpoints: growth inhibition and chlorophyll a (Chl a) content were investigated at 62.5–1000 µg/L over 168 h. In addition, the apurinic/apyrimidinic (AP) sites, randomly amplified polymorphic deoxyribonucleic acid (RAPD) profiles, and genomic template stability (GTS) were assessed to determine the genotoxic effects of nAu. The results show algal growth inhibition at 5 nm BPEI-nAu up to 96 h, and thereafter cell recovery except at the highest concentration of 1000 µg/L. Insignificant growth reduction for cit-nAu (all sizes), as well as 20 and 40 nm BPEI-nAu, was observed over 96 h, but growth promotion was apparent at all exposures thereafter except for 40 nm BPEI-nAu at 250 µg/L. A decrease in Chl a content following exposure to 5 nm BPEI-nAu at 1000 µg/L corresponded to significant algal growth reduction. In genotoxicity studies, a significant increase in AP sites content was observed relative to the control – an indication of nAu ability to induce genotoxic effects irrespective of their size and coating type. For 5 nm- and 20 nm-sized nAu for both coating types and exposure concentrations no differences in AP sites content were observed after 72 and 168 h. However, a significant reduction in AP sites was observed following algae exposure to 40 nm-sized nAu (irrespective of coating type and exposure concentration) at 168 h compared to 72 h. Thus, AP sites results at 40 nm-size suggest likely DNA damage recovery over a longer exposure period. The findings on AP sites content showed a good correlation with an increase in genome template stability and growth promotion observed after 168 h. In addition, RAPD profiles demonstrated that nAu can induce DNA damage and/or DNA mutation to P. subcapitata as evidenced by the appearance and/or disappearance of normal bands compared to the controls. Therefore, genotoxicity results revealed significant toxicity of nAu to algae at the molecular level although no apparent effects were detectable at the morphological level. Overall, findings herein indicate that long-term exposure of P. subcapitata to low concentrations of nAu may cause undesirable sub-lethal ecological effects.The South African National Research Foundation, Department of Science and Technology Professional Development Programme Doctoral grant, the Council for Scientific and Industrial Research (CSIR) and the University of Pretoria.https://www.elsevier.com/locate/aqtox2022-05-24hj2022Chemical Engineerin

Interactions of metal-based engineered nanoparticles with aquatic higher plants : a review of the state of current knowledge

The rising potential for the release of engineered nanoparticles (ENPs) into aquatic environments requires evaluation of risks to protect ecological health. The present review examines knowledge pertaining to the interactions of metal-based ENPs with aquatic higher plants, identifies information gaps, and raises considerations for future research to advance knowledge on the subject. The discussion focuses on ENPs' bioaccessibility; uptake, adsorption, translocation, and bioaccumulation; and toxicity effects on aquatic higher plants. An information deficit surrounds the uptake of ENPs and associated dynamics, because the influence of ENP characteristics and water quality conditions has not been well documented. Dissolution appears to be a key mechanism driving bioaccumulation of ENPs, whereas nanoparticulates often adsorb to plant surfaces with minimal internalization. However, few reports document the internalization of ENPs by plants; thus, the role of nanoparticulates' internalization in bioaccumulation and toxicity remains unclear, requiring further investigation. The toxicities of metal-based ENPs mainly have been associated with dissolution as a predominant mechanism, although nano toxicity has also been reported. To advance knowledge in this domain, future investigations need to integrate the influence of ENP characteristics and water physicochemical parameters, as their interplay determines ENP bioaccessibility and influences their risk to health of aquatic higher plants. Furthermore, harmonization of test protocols is recommended for fast tracking the generation of comparable data.M.Thwala acknowledges the UNESCO Keizo Obuchi Fellowship 2014 undertaken at Environmental Toxicology Unit, Clemson University (SC, USA) and the Thuthuka Programme of the National Research Foundation (South Africa). Sponsorship of the present work by the CSIR under the project ―Nanotechnology Risk Assessment in Aquatic Systems: Experimental and Modelling Approaches‖ is also acknowledged.http://onlinelibrary.wiley.com/journal/10.1002/(ISSN)1552-86182017-07-31hb2016Chemical Engineerin

Aggregation and dissolution of aluminium oxide and copper oxide nanoparticles in natural aqueous matrixes

Aggregation and dissolution kinetics of aluminium oxide nanoparticles (nAl2O3) and copper oxide nanoparticles (nCuO) in deionised water (DIW) and freshwater sourced from two river systems were studied with the objective to understand the influencing factors. Dynamic light scattering and inductively coupled plasma mass spectrometer were used to study aggregation and dissolution, respectively. In DIW, humic acid was observed to have a concentration dependent stabilization effect on ENPs. Increasing the ionic strength destabilised the ENPs. The pH influenced aggregation with maximum aggregation observed at the isoelectric point. ENPs were stable in freshwater systems with HDD < 350 nm at 100 µg/L. Aggregation of both ENPs was concentration dependent. The ENPs exhibited higher stability in freshwater with low, rather than high, concentrations of both natural organic matter (NOM) and electrolytes. Dissolution was higher in Elands river than in Bloubank river water. ENPs had a high tendency for dissolution at low concentrations. NOM impeded dissolution of ENPs by providing a protective coating via steric and electrostatic interaction. Released ions may have formed precipitates and chelate compounds with ligands present in freshwater especially for nCuO where low dissolution was apparent. These findings provide insights on aggregation and dissolution of ENPs in freshwater systems as influenced by source-specific water chemistry. Therefore, it is not possible to make generalized statement on the outcome of ENPs transformation in aquatic systems.The Water Research Commission of South Africa and the University of Pretoria.https://www.springer.com/journal/42452hj2021Chemical Engineerin