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 & Context (language use). The organization has 8070 authors who have published 22749 publications receiving 329408 citations. The organization is also known as: UJ.

Business sustainability: empirical evidence on operational skills in SMEs in South Africa

Abstract: Purpose – Activities in the manufacturing sector are often considered the bedrock of an economy and a key driver of growth and development. Within the South African manufacturing sector, operations skills are reported to be deficient and are often cited as a main cause of failure in small, medium and micro enterprises (SMMEs). This study aims to explore and test this fragile relationship between operations skills and SMME sustainability. It also aims to conduct empirical investigations in a high density SMME manufacturing environment.Design/methodology/approach – Building on previously established literature on SMME sustainability and operations skills, various measures are developed and tested for reliability and validity. Factor analysis is used to identify relevant factors in terms of operations skills. Correlational analysis is then employed to test the hypothesized relationship. The study is cross‐sectional in design and relies on trained fieldworkers administering surveys to a diverse set of SMMEs.F...

Recent progress in the development of semiconductor-based photocatalyst materials for applications in photocatalytic water splitting and degradation of pollutants

Abstract: Photocatalytic approaches in the visible region show promising potential in photocatalytic water splitting and water treatment to boost water purification efficiency. For this reason, developing cost-effective and efficient photocatalysts for environmental remediation is a growing need, and semiconductor photocatalysts have now received more interest owing to their excellent activity and stability. Recently, several metal oxides, sulfides, and nitrides-based semiconductors for water splitting and photodegradation of pollutants have been developed. However, the existing challenges, such as high over potential, wide band gap as well as fast recombination of charge carriers of most of the semiconductors limit their photocatalytic properties. This review summarizes the recent state-of-the-art first-principles research progress in the design of effective visible-light-response semiconductor photocatalysts through several modification processes with a focus on density functional theory (DFT) calculations. Recent developments to the exchange-correlation effect, such as hybrid functionals, DFT + U as well as methods beyond DFT are also emphasized. Recent discoveries on the origin, fundamentals, and the underlying mechanisms of the interfacial electron transfer, band gap reduction, enhanced optical absorption, and electron–holes separation are presented. Highlights on the challenges and proposed strategies in developing advanced semiconductor photocatalysts for the application in water splitting and degradation of pollutants are proposed.

Local economic development in Africa: Global context and research directions

Abstract: This paper locates local economic development research and practice in Africa in a global context. It provides an overview of the international development of local economic development (LED), of its contested definitions and theoretical status, and of existing scholarship on the topic of LED policy and practice specifically across sub-Saharan Africa. Currently there is much more LED research available for South Africa than for the other sub-Saharan African countries. The paper highlights the need for this imbalance to be redressed.

Rapid emergence of subaerial landmasses and onset of a modern hydrologic cycle 2.5 billion years ago

Abstract: The history of the growth of continental crust is uncertain, and several different models that involve a gradual, decelerating, or stepwise process have been proposed1–4. Even more uncertain is the timing and the secular trend of the emergence of most landmasses above the sea (subaerial landmasses), with estimates ranging from about one billion to three billion years ago5–7. The area of emerged crust influences global climate feedbacks and the supply of nutrients to the oceans 8 , and therefore connects Earth’s crustal evolution to surface environmental conditions9–11. Here we use the triple-oxygen-isotope composition of shales from all continents, spanning 3.7 billion years, to provide constraints on the emergence of continents over time. Our measurements show a stepwise total decrease of 0.08 per mille in the average triple-oxygen-isotope value of shales across the Archaean–Proterozoic boundary. We suggest that our data are best explained by a shift in the nature of water–rock interactions, from near-coastal in the Archaean era to predominantly continental in the Proterozoic, accompanied by a decrease in average surface temperatures. We propose that this shift may have coincided with the onset of a modern hydrological cycle owing to the rapid emergence of continental crust with near-modern average elevation and aerial extent roughly 2.5 billion years ago. The use of triple-oxygen-isotope data from continental shales spanning the past 3.7 billion years suggests that continental crust with near-modern average elevation and extent emerged about 2.5 billion years ago.