Several previous attempts to purify bone marrow for sickle-cell transplants have failed.

FORBES: Magazine Article

One of the most notable innovations: the development of a new catalyst material to purify exhaust from diesel or other lean-burning engines.

FORBES: GM: The Big Green Patent Machine

To the long list of great ideas gone bad, add the UV Waterworks--a simple, cheap device to purify filthy drinking water in poor countries.

FORBES: Running dry