Manganese is also used in portland cement mixtures. Manganese is an important element for human health, essential for development, metabolism, and the antioxidant system. Nevertheless, excessive exposure or intake may lead to a condition known as manganism, a neurodegenerative disorder that causes dopaminergic neuronal death and symptoms similar to Parkinson's disease. The classes of enzymes that have manganese cofactors is large and includes oxidoreductases, transferases, hydrolases, lyases, isomerases, ligases, lectins, and integrins. The reverse transcriptases of many retroviruses (though not lentiviruses such as HIV) contain manganese. The best-known manganese-containing polypeptides may be arginase, the diphtheria toxin, and Mn-containing superoxide dismutase (Mn-SOD).
Manganese recovery of the manganese. For further purification, the manganese can then be sent to an electrowinning facility. In 1972 the CIA's Project Azorian, through billionaire Howard Hughes, commissioned the ship "Hughes Glomar Explorer" with the cover story of harvesting manganese nodules from the sea floor. That triggered a rush of activity to collect manganese nodules, which was not actually practical. The real mission of "Hughes Glomar Explorer" was to raise a sunken Soviet submarine, the K-129, with the goal of retrieving Soviet code books. Manganese has no satisfactory substitute in its major applications in metallurgy. In minor applications, (e.g., manganese