Scleroderma refers to a group of rare chronic autoimmune diseases in which the skin and connective tissues tighten and harden; it is a progressive disease. The skin and connective tissues are fibers that make up the framework that supports the body.
Advantages of Carbon Steel compared to other Metals. 1) Faster heating effect. For kitchen use this is especially important as it saves time and reduces the amount of energy used. Stainless Steel, on the other hand, is known to be a poor conductor of heat.
Adding carbon to iron to make steel does make it stronger and tougher, up to a point. Then it will get stronger but less tough (ie like cast iron). Carbon strengthens iron by distorting its crystal latice. This distortion is similar in effect to work hardening. It is unfortunately a very complex effect and depends on how the steel is heat treated and exactly what percentage of carbon is added (<4% by wieght normally). It is not true of all metals.