- ItemGenetic data and radiocarbon dating question Plovers Lake as a Middle Stone Age hominin-bearing site(Elsevier, 2019) Lombard, Marlize; Malmstrom, Helena; Schlebusch, Carina Maria; Svensson, Emma M.; Gunther, Torsten; Coutinho, Alexandra; Edlund, Hanna; Zipfel, Bernhard; Jakobsson, MattiasWe have sampled five out of the eleven previously identified human specimens and some faunal remains from the Plovers Lake site in the Cradle of Humankind, South Africa, for ancient DNA. We were successful in obtaining positive results for three of the human individuals and three ‘buffalo’ teeth. Based on ages obtained for flowstone and one bovid tooth, the site was interpreted previously as a hominin-bearing Middle Stone Age site of more than 60 000 years old. Our work, however, revealed that not all the material accumulated during the Pleistocene. Instead, the sampled humans and bovids most likely represent a Bantu-speaking Iron Age population (mtDNA haplogroup L3d) and their Nguni cattle. Newly obtained radiocarbon dates confirmed that these remains are probably no older than the last 500 years bp. This study demonstrates the usefulness of inter-disciplinary investigation into the human past, and the depositional and stratigraphic complexities that researchers in the Cradle of Humankind need to contend with before interpreting their assemblages.
- ItemAntibacterial and Anticancer Activity and Untargeted Secondary Metabolite Profiling of Crude Bacterial Endophyte Extracts from Crinum macowanii Baker Leaves(Hindawi, 2020-12-10) T Sebola; N Uche-Okereafor; L Mekuto; Maya Makatini; E Green; Vuyo MavumengwanaThis study isolated and identified endophytic bacteria from the leaves of Crinum macowanii and investigated the potential of the bacterial endophyte extracts as antibacterial and anticancer agents and their subsequent secondary metabolites. Ethyl acetate extracts from the endophytes and the leaves (methanol: dichloromethane (1 : 1)) were used for antibacterial activity against selected pathogenic bacterial strains by using the broth microdilution method. The anticancer activity against the U87MG glioblastoma and A549 lung carcinoma cells was determined by the MTS (3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxy-phenyl)-2-(4-sulfophenyl)-2H-tetrazolium) assay. Bacterial endophytes that were successfully isolated from C. macowanii leaves include Raoultella ornithinolytica, Acinetobacter guillouiae, Pseudomonas sp., Pseudomonas palleroniana, Pseudomonas putida, Bacillus safensis, Enterobacter asburiae, Pseudomonas cichorii, and Arthrobacter pascens. Pseudomonas cichorii exhibited broad antibacterial activity against both Gram-negative and Gram-positive pathogenic bacteria while Arthrobacter pascens displayed the least MIC of 0.0625 mg/mL. Bacillus safensis crude extracts were the only sample that showed notable cell reduction of 50% against A549 lung carcinoma cells at a concentration of 100 mu g/mL. Metabolite profiling of Bacillus safensis, Pseudomonas cichorii, and Arthrobacter pascens crude extracts revealed the presence of known antibacterial and/or anticancer agents such as lycorine (1), angustine (2), crinamidine (3), vasicinol (4), and powelline. It can be concluded that the crude bacterial endophyte extracts obtained from C. macowanii leaves can biosynthesize bioactive compounds and can be bioprospected for medical application into antibacterial and anticancer agents.
- ItemCarbon Encapsulated Ternary MnNiCo Oxide Nanoparticles as Electrode Materials for Energy Storage Applications(Wiley, 2020-12) Tarekegn Heliso Dolla; Isiaka A. Lawal; David Billing; K Pruessner; Patrick Ndungu; Dolla, TH; Lawal, IA; Billing, DG; Pruessner, k; Ndungu, PTernary transition metal oxides are promising advanced materials for use as electrode components in electrochemical energy storage systems. However, low electronic/ionic conductivity hinder practical applications. In this study, ternary Mn-Ni-Co oxide nanoparticles were encapsulated in carbon nanosheets, to improve the electrical conductivity and surface area. When tested as supercapacitor electrodes, the materials exhibited specific capacity of 91.2 mAh g(-1)at a current density of 1 A g(-1)in 2 M KOH. Moreover, after 3000 cycles the composite achieved a specific capacity of 74.6 mAh g(-1)at a current density of 6 A g(-1)and high capacitance retention of 96.4 %.
- ItemTruncated 21st-century trajectories of progressive international solidarity(Routledge, 2019-11-10) Bond, P.What potentials exist for realizing a new internationalism consistent with the visions of Samir Amin, Africa’s greatest political economist and one of the leading Marxists of his generation? To answer requires tracing back several decades, to interpret Amin’s own strategy for establishing first, continental and then, global networks mixing radical scholars and activists. Many missteps were taken, among which were gaps between top-down intellectual formulations (and manifestos) and bottom-up strategic narratives (often lacking a coherent ideology). Because of these limitations, even Amin’s most opportune political networking faltered, proving unsustainable. On most such occasions, it was Amin’s own auto-critique that assisted his allies in developing more profound formulations. It is in these various initiatives to which Amin generously gave his time, energy, resources and political commitment that we can learn some of the most powerful lessons for future internationalism.