This communication elaborates the irreversibility analysis of the flow of Prandtl nanofluid along with thermal radiation past a permeable stretched surface embedded in a Darcy-Forchheimer medium. The activation and chemical impressions along with effects of thermophoretic and Brownian motion are as well examined. The flow symmetry of the problem is modeled mathematically and leading equations are rehabilitated into nonlinear ordinary differential equations (ODEs) through the assistance of suitable similarity variables. The Keller-box technique in MATLAB is employed to draw the impacts of the contributing elements on the velocity field, temperature distribution, and concentration. The impact of the Prandtl fluid parameter has mounting performance for the velocity whereas conflicting behavior is examined in the temperature profile. The achieved numerical results are matched correspondingly with the present symmetrical solutions in restrictive cases and fantastic agreement is scrutinized. In addition, the entropy generation uplifts for the growing values of the Prandtl fluid parameter, thermal radiation, and Brinkman number and decreases for growing numbers of the inertia coefficient parameter. It is also discovered that the coefficient of friction decreases for all parameters involved in the momentum equation. Features of nanofluids can be found in a variety of real-world fields, including microfluidics, industry, transportation, the military, and medicine.
The introduction of effective vaccines in December 2020 marked a significant step forward in the global response to COVID-19. Given concerns with access, acceptability, and hesitancy across Africa, there is a need to describe the current status of vaccine uptake in the continent. An exploratory study was undertaken to investigate these aspects, current challenges, and lessons learnt across Africa to provide future direction. Senior personnel across 14 African countries completed a self-administered questionnaire, with a descriptive analysis of the data. Vaccine roll-out commenced in March 2021 in most countries. COVID-19 vaccination coverage varied from low in Cameroon and Tanzania and up to 39.85% full coverage in Botswana at the end of 2021; that is, all doses advocated by initial protocols versus the total population, with rates increasing to 58.4% in Botswana by the end of June 2022. The greatest increase in people being fully vaccinated was observed in Uganda (20.4% increase), Botswana (18.5% increase), and Zambia (17.9% increase). Most vaccines were obtained through WHO-COVAX agreements. Initially, vaccination was prioritised for healthcare workers (HCWs), the elderly, adults with co-morbidities, and other at-risk groups, with countries now commencing vaccination among children and administering booster doses. Challenges included irregular supply and considerable hesitancy arising from misinformation fuelled by social media activities. Overall, there was fair to reasonable access to vaccination across countries, enhanced by government initiatives. Vaccine hesitancy must be addressed with context-specific interventions, including proactive programmes among HCWs, medical journalists, and the public.