Influence of air diffusion on the OH radicals and atomic O distribution in an atmospheric Ar (bio)plasma jet

Treatment of samples with plasmas in biomedical applications often occurs in ambient air. Admixing air into the discharge region may severely affect the formation and destruction of the generated oxidative species. Little is known about the effects of air diffusion on the spatial distribution of OH radicals and O atoms in the afterglow of atmospheric-pressure plasma jets. In our work, these effects are investigated by performing and comparing measurements in ambient air with measurements in a controlled argon atmosphere without the admixture of air, for an argon plasma jet. The spatial distribution of OH is detected by means of laser-induced fluorescence diagnostics (LIF), whereas two-photon laser-induced fluorescence (TALIF) is used for the detection of atomic O. The spatially resolved OH LIF and O TALIF show that, due to the air admixture effects, the reactive species are only concentrated in the vicinity of the central streamline of the afterglow of the jet, with a characteristic discharge diameter of similar to 1.5 mm. It is shown that air diffusion has a key role in the recombination loss mechanisms of OH radicals and atomic O especially in the far afterglow region, starting up to similar to 4mm from the nozzle outlet at a low water/oxygen concentration. Furthermore, air diffusion enhances OH and O production in the core of the plasma. The higher density of active species in the discharge in ambient air is likely due to a higher electron density and a more effective electron impact dissociation of H2O and O-2 caused by the increasing electrical field, when the discharge is operated in ambient air

Decline in acute coronary syndrome hospitalisation rates during COVID-19 lockdown in private hospitals in South Africa

We conducted a study of admission rates of acute coronary syndrome (ACS) in all Mediclinic hospitals in South Africa. The aim of the study was to quantify the extent of change in admission rates of ACS subtypes and to establish the degree of change in subtype proportions in the private sector assumed to be related to COVID-19 and/or lockdown implementation. Time intervals were demarcated by lockdown measures (March: pre-lockdown versus April: post-lockdown implementation), and comparisons were performed with equitable time periods (2019 versus 2020). For the comparison of proportions, data for April and May were summated

Review of power line communications standards in Africa

The standards in power line communications (PLC) calibrate parameters such as frequencies allocation, signal level, security, topology of the network and many others parameters. The leap forward of power line communications technology is motivated by the willingness of the standardization organizations (SDO)s such as ITU, IEC, ISO, IEEE, CENELEC to define how the technologies are going to be deployed. This paper presents the different SDOs, Alliances and groups regulating the PLC sector. The interoperability and coexistence for some technologies are underlined. The process of developing PLC standards by ITU, IEEE 1901, CENELEC is described. The advantages and disadvantages of using PLC technology in Africa are discussed

Detecting the zero-crossing message to achieve low bit transmission over H-bridge inverter

Home automation and smart grid development is motivated by many advantageous situations that include the demands on renewable energy and the advantages provided by power line communications technology (PLC). The integration of solar energy into conventional grid implies the control of different modules included in the system. Remote control seems to be the control mode by excellence, in which communication is the main point to focus on. The pulse width modulation (PWM) scheme used to control the inverter is also used to modulate the zero-crossing point of the output sine wave of the inverter, to transfer data. The zero-crossing modulation technique is proposed and basic elements to construct the model are proposed. Simulated constellations of the received signal are presented

Platinum and palladium on carbon nanotubes:Experimental and theoretical studies

<p>Pristine and oxygen plasma functionalised carbon nanotubes (CNTs) were studied after the evaporation of Pt and Pd atoms. High resolution transmission electron microscopy shows the formation of metal nanoparticles at the CNT surface. Oxygen functional groups grafted by the plasma functionalization act as nucleation sites for metal nanoparticles. Analysis of the C1s core level spectra reveals that there is no covalent bonding between the Pt or Pd atoms and the CNT surface. Unlike other transition metals such as titanium and copper, neither Pd nor Pt show strong oxygen interaction or surface oxygen scavenging behaviour. (C) 2013 Elsevier B.V. All rights reserved.</p>