This model is based on the in vitro skin model Skin2 [5] which had been discontinued in October 1996. It was further proposed by industry to apply the model in a tiered strategy to identify those chemicals that are predicted to be likely to be phototoxic in the 3T3-NRU-PT but are negative in vivo [6].
401(k) contribution rules. On a pretax basis, employees can't contribute above certain limits. In 2015, for instance, the limit is $18,000; those 50 and older can make additional catch-up contributions of $6,000.This money is not counted toward income, and all gains are tax-deferred. The limits are the same for Roth 401(k)s, though the contributions do count toward income and all gains are tax-free.But employees can sock away a lot more retirement cash if their company plan offers an after-tax option in a traditional 401(k).he limits are the same for Roth 401(k)s, though the contributions do count toward income and all gains are tax-free. But employees can sock away a lot more retirement cash if their company plan offers an after-tax option in a traditional 401(k).
But keep in mind that if you also contribute to another employer's 401(k), 403(b), SIMPLE, or SAR-SEP plan, your total contributions to all of these plans--both pretax and Roth--can't exceed $18,000 in 2015 ($24,000 if you're age 50 or older). Roth 401(k) is simply a traditional 401(k) plan that accepts Roth 401(k) contributions. Roth 401(k) contributions are made on an after-tax basis, just like Roth IRA contributions.