University of Johannesburg

About: University of Johannesburg is a education organization based out in Johannesburg, South Africa. It is known for research contribution in the topics: Population & Tourism. The organization has 8070 authors who have published 22749 publications receiving 329408 citations. The organization is also known as: UJ.

Efficient removal of rhodamine 6G dye from aqueous solution using nickel sulphide incorporated polyacrylamide grafted gum karaya bionanocomposite hydrogel

Abstract: This research paper reports the synthesis and usage of the polyacrylamide (PAAm) grafted gum karaya (Gk) and nickel sulphide nanoparticle based hydrogel to effectively remove rhodamine 6G dye (R6G) from aqueous solution. Initially, the hydrogel polymer of the Gk with the PAAm was synthesized using the graft co-polymerization technique. In the second step, the nickel sulphide nanoparticles were incorporated in situ within the hydrogel polymer matrix. The synthesized hydrogel nanocomposite was characterized using different characterization techniques such as XRD, FTIR, SEM, and TEM. The changes in the surface area, pore volume and pore diameter after the incorporation of nanoparticles were studied using the BET technique. The adsorption of R6G onto the hydrogel nanocomposite followed the Langmuir adsorption isotherm with a maximum adsorption capacity of 1244.71 mg g−1. The adsorption kinetics followed the pseudo-second order rate model. Furthermore, various thermodynamic parameters such as ΔS°, ΔH° and ΔG° were calculated to check the spontaneity and nature of the process of adsorption. The hydrogel nanocomposite was used for five successive cycles of adsorption–desorption. Therefore, the nanocomposite hydrogels have proved their potential for the removal of cationic dyes from aqueous solutions.

Search for anomalous production of prompt same-sign lepton pairs and pair-produced doubly charged Higgs bosons with s =8 TeV pp collisions using the ATLAS detector

Abstract: A low-background inclusive search for new physics in events with same-sign dileptons is presented The search uses proton-proton collisions corresponding to 203 fb−1 of integrated luminosity taken in 2012 at a centre-of-mass energy of 8 TeV with the ATLAS detector at the LHC Pairs of isolated leptons with the same electric charge and large transverse momenta of the type e±e±, e±μ±, and μ±μ± are selected and their invariant mass distribution is examined No excess of events above the expected level of Standard Model background is found The results are used to set upper limits on the cross-sections for processes beyond the Standard Model Limits are placed as a function of the dilepton invariant mass within a fiducial region corresponding to the signal event selection criteria Exclusion limits are also derived for a specific model of doubly charged Higgs boson production

The oxidative toxicity of Ag and ZnO nanoparticles towards the aquatic plant Spirodela punctuta and the role of testing media parameters

Abstract: The toxicity effects of silver (nAg) and zinc oxide (nZnO) engineered nanoparticles (ENPs) on the duckweed Spirodela punctuta were studied to investigate the potential risks posed by these ENPs towards higher aquatic plants. The influence of media abiotic factors on the stability of the ENPs was also evaluated. Marked agglomeration of ENPs was observed after introduction into testing media whereby large particles settled out of suspension and accumulated at the bottom of testing vessels. The high ionic strength (IS) promoted agglomeration of ENPs because it reduced the inter-particle repulsion caused by a reduction in their surface charge. Low dissolution was observed for nAg, reaching only 0.015% at 1000 mg L−1, whilst improved dissolution was observed for nZnO, only falling below analytical quantification at 0.1 mg L−1 and lower. The quantification of free radicals namely, reactive oxygen and nitrogen species (ROS/RNS) and hydrogen peroxide (H2O2), indicated the induction of oxidative stress in plants exposed to the ENPs. A definite dose influence was observed for ROS/RNS volumes in plants exposed to nZnO for 14 days, a response not always observed. The total antioxidant capacity (TAC) and superoxide dismutase (SOD) activity in plants indicated varying degrees of oxidative toxicity caused by exposure to ENPs. This toxicity was driven mainly by particulates in plants exposed to nAg, whilst dissolved Zn2+ was the main driver for toxicity in plants exposed to nZnO. Our findings suggest that the toxicity of nAg and nZnO could be caused by both the particulates and ionic forms, as modified by media properties.

The medical ethnobotany of Lesotho: a review

Abstract: Traditional healing in Lesotho is reviewed, focusing on four aspects: 1, cultural practices; 2, traditional health care practitioners; 3, dosage forms; 4, the materia medica . Cultural practices are strongly associated with the belief that intangible forces are responsible for human happiness and misery. A total of 303 plant species are used medicinally (including 25 alien species), representing eight pteridophyte and 75 angiosperm families, of which the most important are Asteraceae, Fabaceae, Hyacinthaceae, Apocynaceae, Scrophulariaceae, Lamiaceae and Poaceae. Dicoma anomala (used mainly for digestive ailments) and Artemisia afra (used mainly for respiratory ailments) appear to be the best known and most widely used medicinal plants amongst a total of 37 species that have been cited four or more times in the literature. About 50 species are variously employed for magic and sorcery. There are no new species records but 36 new uses are reported. Our conclusion is that the medicinal plants of Lesotho are relatively well recorded and that this review will allow detailed comparisons with other African healing cultures.