> Alas, they were phased out due to backwash and contamination from the injection process. That's how the army gave my aunt Hep C. Numerous attempts have been

> Alas, they were phased out due to backwash and contamination from the injection process. That's how the army gave my aunt Hep C. Numerous attempts have been made to solve this "backwash" issue, but fluid dynamics is a harsh mistress. When you shoot a droplet at a fluid interface, the interface shoots back.