香蕉视频

(Chemistry professor Joe Schwarcz): A child born into a wealthy family is said to have "been born with a silver spoon in his mouth." The silver represents wealth, but thanks to the "oligodynamic effect," it may even have a connection to health.

Discovered in 1893 by the Swiss botanist Karl Wilhelm von Nageli, the oligodynamic effect refers to the toxic effect of metal ions on living organisms such as bacteria, algae and fungi. Copper, lead, zinc, gold and mercury can also furnish ions that will produce an antimicrobial effect, but the toxicity of lead and mercury preclude their use in this fashion. That wasn't always the case.

Mercury at one time was commonly used to treat syphilis, giving rise to the expression, "a night with Venus, a lifetime with mercury." However, because of mercury's toxicity, that lifetime was often quite short. Copper and silver, on the other hand, have low toxicity by comparison and can be effectively used to battle bacteria.