【英语时差8,16】防臭袜子-下（在线收听）

There are several kinds of odor preventing and odor destroying treatments for textiles. For the most part, they work by killing or inhibiting the bacteria and fungi that cause odors. For example, these socks contain Quaternary Ammonium Compounds, or QACs. QACs are complex molecules with one end that binds tightly to the surface of the treated fibers. The rest of the molecule is made up of a positively charged nitrogen atom and a long chain of carbons. You can think of the QAC molecule as an electrically charged sword. The long chain of carbons punctures the cell membrane of a microbe, allowing the charged nitrogen to electrically disrupt the cell’s contents. Since nothing is bound permanently to the now dead cell, the QAC doesn’t lose strength and is ready to destroy the next offending microbe that crosses its path.