Vision (Definition) Vision is a feature of a person's brain that allows him to see. He must have normal eyes, optic nerves (that stretch from the eyes to the back of his brain), and visual cortex (the vision center in the brain), in order to see properly. An ophthalmologist is a doctor specializing in vision. ...Read more.
The halogens or halogen elements (/ËhÃ¦lÉdÊÉn, ËheÉª-, -loÊ-, -ËdÊÉn/) are a group in the periodic table consisting of five chemically related elements: fluorine (F), chlorine (Cl), bromine (Br), iodine (I), and astatine (At). The artificially created element 117 (ununseptium) may also be a halogen.
They are comprised of two chemicals which, when mixed and heated, form liquid polyurethane prior to being further processed. These chemicals are polyol, a type of complex alcohol, and diisocyanate, a petroleum byproduct that reacts strongly with alcohol.By combining the two, a stable long-chain molecule is formed.hey are comprised of two chemicals which, when mixed and heated, form liquid polyurethane prior to being further processed. These chemicals are polyol, a type of complex alcohol, and diisocyanate, a petroleum byproduct that reacts strongly with alcohol.