Due to construction and functional characteristics above described, with the internal reflux column it is possible to get selective the separation of components of extremely complex mixtures, with similar chemico-physical characteristics, not economically separable otherwise.
Uniform numbers in American football are unusual compared to those in other sports. They are displayed in more locations on the uniform; they are universally worn on both the front and back of the jersey; and in many cases TV numbers are displayed on either the jersey sleeves, the shoulder pad, or occasionally on the helmets.
Football helmet. The football helmet is a piece of protective equipment used mainly in American football and Canadian football. It consists of a hard plastic shell with thick padding on the inside, a face mask made of one or more plastic-coated metal bars, and a chinstrap. Each position has a different type of face mask to balance protection and visibility, and some players add polycarbonate visors to their helmets, which are used to protect their eyes from glare and impacts. Helmets are a requirement at all lev