When the researchers tested the surface a day later, they found that just 1 in every 100,000 to 1,000,000 bacteria had survived. (sciencenewsforstudents.org)
It's very easy to produce fake coins, cause the only way to test if gold is real gold is to melt it, with radiography you can only test the surface of gold deep less than 1 mm. (money.stackexchange.com)
The researchers tested those surfaces with several oils, each having a different viscosity (Vis - KOSS - ih - tee). (sciencenewsforstudents.org)