There have been 45 men elected as president in U.S. history, but only a few appear on coins and bills that most people ...

Are your old pennies worth millions? Experts say you shouldn't bank on it. But some are worth hundreds of dollars. Here's how to check yours.

Are your old pennies worth millions? Experts say you shouldn't bank on it. But some are worth hundreds of dollars. Here's how ...

The roles of silver core size (40–100 nm) and fluorophore–metal distance (5–30 nm) were systematically examined. Fluorescence enhancement factor exceeding 30 was observed at silver core size of 70 nm ...