Spark Discharge Aerosol-Generated Copper-Based Nanoparticles: Structural & Optical Properties; Application on the Antiviral (SARS-CoV-2) and Antibacterial Improvement of Face Masks.

Nanoparticle formation by Spark Discharge Aerosol Generation offers low-cost fabrication of nanoparticles, without the use of chemicals or vacuum. It produces aerosol particles of a few nanometers in size with high purity. In this work, copper-based -CuO (tenorite) and Cu- nanoparticles are produced, characterized and used to modify face mask air filters, achieving the introduction of antibacterial and antiviral properties. A range of characterization techniques have been employed, down to the atomic level. The majority of the particles are CuO (of a few nanometers in size that agglomerate to form aggregates), the remainder being a small number of larger Cu particles. The particles were deposited on various substrates, mainly fiber filters in order to study them and use them as biocidal agents. On face masks, their antibacterial activity against Escherichia coli (E.coli) results in a 100 % decrease in bacteria cell viability. Their antiviral activity on face masks results in a 90 % reduction of the Severe Acute Respiratory Syndrome Corona Virus 2 (SARS-CoV-2) viability, 15 minutes post the application of the virus stock solution. This highlights the effectiveness of this approach, its simplicity, its low cost and its excellent environmental credentials.

Radioactivity evaluation and radiation dosimetry assessment in Greek honey.

Greek honey was examined for 238U, 234U, 210Pb, 210Po, 40K, and 137Cs levels. 238U was calculated from 0.013 ± 0.007 Bq kg-1 to 0.10 ± 0.02 Bq kg-1 while 234U ranged from 0.017 ± 0.009 Bq kg-1 to 0.11 ± 0.03 Bq kg-1. 210Pb measured from 0.04 ± 0.02 Bq kg-1 to 1.70 ± 0.26 Bq kg-1 whereas 210Po activity determined between 0.02 ± 0.01 Bq kg-1 and 2.31 ± 0.34 Bq kg-1. 40 K found at the range of 7.9 ± 1.6 Bq kg-1 to 102.2 ± 19.7 Bq kg-1 and 137Cs 0.3 ± 0.1 Bq kg-1 up to 0.8 ± 0.1 Bq kg-1. Uranium isotopes and 210Po were determined via alpha spectrometry. 210Pb was also indirectly determined by alpha spectrometry. 40 K and 137Cs were measured through γ-ray spectrometry. An annual dose calculation was performed for different age groups.

A RADIATION DOSIMETRY ASSESSMENT OF WORKERS IN GREEK STYLE ROTISSERIES THAT USE PELLETS CONTAMINATED BY 137Cs AND 90Sr.

This work evaluates the 137Cs and 90Sr content of wood pellets of the Greek energy market and additionally calculates worker exposure in Greek catering establishments (rotisseries). Wood pellets and ash samples were analysed through high resolution gamma-ray spectroscopy and liquid scintillation. Imported pellets had higher 137Cs concentrations, especially pellets that were imported in bulk. Greek pellets had very smaller 137Cs amounts. Despite the high variation in 137Cs content the 137Cs exemption levels were not exceeded in any case. However, if an enrichment factor of 300 is assumed, some ashes samples may exceed 13000 Bq/kg. The highest amounts of 90Sr were measured in ashes from pellets manufactured abroad in 2015, with up to 1060 Bq/kg. A linear regression model of the ratio of 137Cs to 90Sr activity followed our data well, and other sets of data partially. A dosimetry assessment of kitchen employees revealed that maximum possible dose intake reached 400 nSv/year.