1 Therefore, the idea is to use a set of optimum conditions to get the most efficient yield of ammonia and this involves getting a low % yield (e.g. 8% - 15% conversion) but fast. 2  Described below are the conditions to give the most economic production of ammonia.
Causes of Vitiligo. Melanin is the pigment that gives the skin its characteristic color. Vitiligo is caused by a loss of pigment in the skin, due to destruction of pigment-forming cells known as melanocytes. The exact cause of the destruction of these cells is not known. One possible explanation might be that the body's immune system destroys the cells, as in other autoimmune conditions.
Sometimes the hair in these areas also turns white. It happens when the skin's pigment-producing cells called melanocytes die. White patches can appear anywhere on the body (generalized vitiligo) or just in one area (focal vitiligo). Researchers suspect that vitiligo is one of many autoimmune diseases.he exact cause of vitiligo is unknown at this time; however, scientists have several different theories. One theory suggests that vitiligo is an autoimmune disease in which the body destroys melanocytes for no known reason.