And it was proposed by my thesis advisor Professor Weisskopf that we work on this problem to understand the effect of the impurities in scattering electrons and interfering with their motion.

VOA: special.2010.11.09

These impurities in the air cause allergic reactions.

VOA: special.2009.07.28

He calls it "cow power to horsepower." Leonhardt says the challenge is to cost-effectively remove impurities from the manure-derived methane.

VOA: standard.2010.02.23

In the public health care system, for example, only two hospitals are equipped with dialysis machines, which remove impurities from the blood when the kidneys can not do it.

VOA: standard.2010.05.30

Those impurities rapidly corrode engine parts.

VOA: standard.2010.02.23