Air conditioning eventually reach the upper atmosphere. Once the refrigerant reaches the stratosphere, UV radiation from the Sun homolytically cleaves the chlorine-carbon bond, yielding a chlorine radical. These chlorine radicals catalyze the breakdown of ozone into diatomic oxygen, depleting the ozone layer that shields the Earth's surface from strong UV radiation. Each chlorine radical remains active as a catalyst until it binds with another radical, forming a stable molecule and quenching the chain reaction. Prior to 1994, most automotive air conditioning systems used R-12 as a refrigerant. It was replaced with R-134a refrigerant, which has no ozone depletion potential. Old R-12 systems
Protein S (Myxococcus xanthus) Protein S (Myxococcus xanthus) Protein S is a protein found in "Myxococcus xanthus". Its name derives from being the "S" band in an alphabetical ordering of proteins run from Myxococcus xanthus cell contents on a SDS-denaturing gel. Its study was initially prompted by the huge increase in Protein S production during sporulation of Myxococcus xanthus. Though it has been purported as recently as 1994 that Protein S enables myxospores of Myxococcus xanthus higher resistance to endure heating, desiccation, UV radiation and sonication no such evidence exists. The work that cites claims no such evidence: and there are other studies that