Polonium in the Earth's crust are not harmful. Polonium has been found in tobacco smoke from tobacco leaves grown with phosphate fertilizers. Because it is present in small concentrations, isolation of polonium from natural sources is a tedious process. The largest batch of the element ever extracted, performed in the first half of the 20th century, contained only (9 mg) of polonium-210 and was obtained by processing 37 tonnes of residues from radium production. Polonium is now usually obtained by irradiating bismuth with high-energy neutrons or protons. In 1934, an experiment showed that when natural Bi is bombarded with neutrons, Bi
Discover Card Discover Card Discover is a credit card brand issued primarily in the United States. It was introduced by Sears in 1985. When launched, Discover did not charge an annual fee and offered a higher-than-normal credit limit, features that were disruptive to the existing credit card industry. A subsequent innovation was "Cashback Bonus" on purchases. Most cards with the Discover brand are issued by Discover Bank, formerly the Greenwood Trust Company. Discover transactions are processed through the Discover Network payment network. In 2005, Discover Financial Services acquired Pulse, an electronic funds transfer network, allowing it to market and issue debit and