University of South Africa

About: University of South Africa is a education organization based out in Pretoria, South Africa. It is known for research contribution in the topics: Context (language use) & Population. The organization has 8478 authors who have published 19960 publications receiving 237688 citations. The organization is also known as: Unisa.

Enhancement of the isopropanol gas sensing performance of SnO2/ZnO core/shell nanocomposites

Abstract: Pure SnO2, ZnO nanoparticles, and a SnO2/ZnO core/shell nanocomposite (NC) were prepared via a sol–gel technique. The structure and morphology of the obtained materials were characterized by X-ray diffraction (XRD), micro-Raman spectroscopy, high-resolution transmission electron microscopy (HRTEM), and scanning electron microscopy (SEM). The results showed that highly crystalline materials were formed, and the resulting composites exhibited core/shell structure with a size of 30 nm, whereas the fabricated films exhibited porous morphology. The gas sensing performance of the SnO2, ZnO nanoparticles, and the SnO2/ZnO NC films was investigated for different volatile organic compound (VOC) vapors in the temperature range from 150 to 350 °C. The gas sensing results confirmed that the SnO2/ZnO NC film shows a high selectivity, sensitivity, good stability, and fast response time towards isopropanol at the optimum operating temperature of 300 °C.

Mobile Learning: Moving Past the Myths and Embracing the Opportunities.

Abstract: Mobile learning (mLearning) in the open and distance learning landscape, holds promise and provides exciting new opportunities. In order to understand and embrace these opportunities within various contexts and circumstances it is imperative to understand the essence of the phenomenon. In this regard, we first need to understand the core fundamentals of mLearning and gain insight in what mLearning entails. Using critical reflection, this paper clarifies what mLearning is by invalidating myths and misperceptions related to mLearning. Acknowledging the lessons learnt through past experience, the authors then explore the opportunities that mLearning provides. mLearning challenges and risks are discussed to assist those who are keen to embrace these opportunities, in avoiding unnecessary risks and pitfalls. The paper concludes by sharing a few thoughts on the future of mLearning. These perspectives on mLearning seek to provide an overview of what mobile learning entails, recognise the achievements of mobile learning to date, and stimulate an appetite to embrace the opportunities in open and distance learning, while minimising the potential negative effects of technological, social and pedagogical change.

A Holistic Professional Development model for South African physical science teachers

Abstract: The state of mathematics and science education in South Africa is a cause for concern This situation can be attributed, in part, to many mathematics and science teachers’ limited content knowledge, ineffective teaching approaches, and unprofessional attitudes To address these three problem areas simultaneously, a holistic model for the development of Grades 10 to 12 Physical Science teachers was constructed and evaluated against national and international benchmarks The effects of the model were assessed over a period of four years with 75 teachers The model was developed in a distance education context, with no face-to-face contact required It comprises the following elements: a study guide which integrates the development of teachers’ content knowledge, pedagogical content knowledge, cognitive skills and experimental skills; reflective journals; assignments; workshops; peer support and science kits We briefly describe the research that culminated in the Holistic ProfessionalDevelopment (HPD) model, followed by an account of each element of the model We then present evidence that suggests that the model is effective in helping teachers develop along three desired dimensions, namely, content knowledge, teaching approaches, and professional attitudes

A simple mathematical model for Ebola in Africa

Abstract: We deal with the following question: Can the consumption of contaminated bush meat, the funeral practices and the environmental contamination explain the recurrence and persistence of Ebola virus disease outbreaks in Africa? We develop an SIR-type model which, incorporates both the direct and indirect transmissions in such a manner that there is a provision of Ebola viruses. We prove that the full model has one (endemic) equilibrium which is locally asymptotically stable whereas, it is globally asymptotically stable in the absence of the Ebola virus shedding in the environment. For the sub-model without the provision of Ebola viruses, the disease dies out or stabilizes globally at an endemic equilibrium. At the endemic level, the number of infectious is larger for the full model than for the sub-model without provision of Ebola viruses. We design a nonstandard finite difference scheme, which preserves the dynamics of the model. Numerical simulations are provided.