Institution
University of Johannesburg
Education•Johannesburg, South Africa•
About: University of Johannesburg is a education organization based out in Johannesburg, South Africa. It is known for research contribution in the topics: Population & Context (language use). The organization has 8070 authors who have published 22749 publications receiving 329408 citations. The organization is also known as: UJ.
Papers published on a yearly basis
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TL;DR: Organic-inorganic hybrid of chitosan and nanoclay was chosen to develop a nanomaterial with combine properties of hydrophilicity of an organic polycation and adsorption capacity of inorganic polyanion to remove chromium(VI) from aqueous solution.
241 citations
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TL;DR: In this paper, the authors fit the observed time-delays and optical spectral energy distribution using a disc reprocessing model, which delivers estimates for the nuclear reddening, the product of black hole mass and accretion rate, and the distance to each object.
Abstract: The thermal reprocessing hypothesis in active galactic nuclei (AGN), where extreme ultraviolet/X-ray photons are reprocessed by the accretion disc into optical/UV photons, predicts wavelength-dependent time-delays between the optical continuum at different wavelengths. Recent photometric monitoring by Sergeev et al. has shown that the time-delay is observed in 14 AGN, and generally seen to increase with increasing wavelength, as predicted in the reprocessing scenario. We fit the observed time-delays and optical spectral energy distribution using a disc reprocessing model. The model delivers estimates for the nuclear reddening, the product of black hole mass and accretion rate, and the distance to each object. However, the distances at face value give H0 = 44 ± 5k m s −1 Mpc −1 ‐ a factor of 1.6 smaller than generally accepted. We discuss the implications of this on the reprocessing model.
240 citations
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TL;DR: These age results demonstrate that a morphologically primitive hominin, Homo naledi, survived into the later parts of the Pleistocene in Africa, and indicate a much younger age for the Homo nalingi fossils than have previously been hypothesized based on their morphology.
Abstract: Species of ancient humans and the extinct relatives of our ancestors are typically described from a limited number of fossils. However, this was not the case with Homo naledi. More than 1500 fossils representing at least 15 individuals of this species were unearthed from the Rising Star cave system in South Africa between 2013 and 2014. Found deep underground in the Dinaledi Chamber, the H. naledi fossils are the largest collection of a single species of an ancient human-relative discovered in Africa. After the discovery was reported, a number of questions still remained. Not least among these questions was: how old were the fossils? The material was undated, and predictions ranged from anywhere between 2 million years old and 100,000 years old. H. naledi shared several traits with the most primitive of our ancient relatives, including its small brain. As a result, many scientists guessed that H. naledi was an old species in our family tree, and possibly one of the earliest species to evolve in the genus Homo. Now, Dirks et al. – who include many of the researchers who were involved in the discovery of H. naledi – report that the fossils are most likely between 236,000 and 335,000 years old. These dates are based on measuring the concentration of radioactive elements, and the damage caused by these elements (which accumulates over time), in three fossilized teeth, plus surrounding rock and sediments from the cave chamber. Importantly, the most crucial tests were carried out at independent laboratories around the world, and the scientists conducted the tests without knowing the results of the other laboratories. Dirks et al. took these extra steps to make sure that the results obtained were reproducible and unbiased. The estimated dates are much more recent than many had predicted, and mean that H. naledi was alive at the same time as the earliest members of our own species – which most likely evolved between 300,000 and 200,000 years ago. These new findings demonstrate why it can be unwise to try to predict the age of a fossil based only on its appearance, and emphasize the importance of dating specimens via independent tests. Finally in two related reports, Berger et al. suggest how a primitive-looking species like H. naledi survived more recently than many would have predicted, while Hawks et al. describe the discovery of more H. naledi fossils from a separate chamber in the same cave system.
240 citations
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TL;DR: In this paper, an early assemblage from Sibudu Cave, KwaZulu-Natal, South Africa, was used to detect bow and arrow technology in use there 64 millennia ago.
Abstract: The invention of the bow and arrow was a pivotal moment in the human story and its earliest use is a primary quarry of the modern researcher. Since the organic parts of the weapon – wood, bone, cord and feathers – very rarely survive, the deduction that a bow and arrow was in use depends heavily on the examination of certain classes of stone artefacts and their context. Here the authors apply rigorous analytical reasoning to the task, and demonstrate that, conforming to their exacting checklist, is an early assemblage from Sibudu Cave, KwaZulu-Natal, South Africa, which therefore suggests bow and arrow technology in use there 64 millennia ago.
240 citations
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TL;DR: In this paper, a review demonstrates the late advancements of nanotechnology in the synthesis of nanoadsorbents containing bentonite and its composites and their ability to absorb variety of inorganic contaminants available in the water.
239 citations
Authors
Showing all 8414 results
Name | H-index | Papers | Citations |
---|---|---|---|
Vinod Kumar Gupta | 165 | 713 | 83484 |
Arnold B. Bakker | 135 | 506 | 103778 |
Trevor Vickey | 128 | 873 | 76664 |
Ketevi Assamagan | 128 | 934 | 77061 |
Diego Casadei | 123 | 733 | 69665 |
Michael R. Hamblin | 117 | 899 | 59533 |
E. Castaneda-Miranda | 117 | 545 | 56349 |
Xiaoming Li | 113 | 1932 | 72445 |
Katharine Leney | 108 | 459 | 52547 |
M. Aurousseau | 103 | 403 | 44230 |
Mika Sillanpää | 96 | 1019 | 44260 |
Sahal Yacoob | 89 | 408 | 25338 |
Evangelia Demerouti | 85 | 236 | 49228 |
Lehana Thabane | 85 | 994 | 36620 |
Sahal Yacoob | 84 | 399 | 35059 |