Lasers can cause damage in biological tissues, both to the eye and to the skin, due to several mechanisms. Thermal damage, or burn, occurs when tissues are heated to the point where denaturation of proteins occurs. Another mechanism is photochemical damage, where light triggers chemical reactions in tissue.
March 9: Teams are allowed to begin negotiating with other teamsâ players who are set to become unrestricted free agents at the end of the league year. This is the first time the NFL is providing a window to negotiate with other teamsâ free agents prior to the start of free agency.
When the 2017 league year begins at 4 p.m. ET on March 9, the free agency and trading period officially opens, and all contracts can become formalized. MORE: Mock Draft 2017. NFL free agents 2017: Top unrestricted players. The class of 2017 has some big offensive names, but the core of most valuable studs lie on defense. Here is Sporting News' ranking of the best 20 unrestricted free agents, some of which have been taken off the open market with franchise tags and re-signings.