▁safety ▁of ▁food ▁and ▁water ▁supply . ▁ ▁In ▁the ▁late ▁ 1 9 8 0 s , ▁Ch ang ▁discovered ▁that ▁the ▁state - of - the - art ▁method ▁for ▁detect ing ▁E . ▁col i ▁held ▁substantial ▁fla ws . ▁The ▁new ▁test , ▁produced ▁by ▁Ch ang , ▁provided ▁accurate ▁results ▁in ▁a ▁day ' s ▁time , ▁versus ▁three ▁or ▁four ▁days ▁for ▁the ▁century - old ▁col iform ▁test . ▁Ch ang ▁and ▁the ▁under grad uate ▁research er ▁became ▁co - in vent ors ▁on ▁a ▁pat ent ▁for ▁" Col it ag ", ▁and ▁on ▁two ▁pat ents ▁since . ▁ ▁Ch ang ▁has ▁taught ▁a ▁sem inar ▁class ▁in ▁the ▁past ▁titled ▁" The ▁F resh man ▁Exper ience ". ▁In ▁the ▁sem inar , ▁students ▁pick ▁discussion ▁topics , ▁interview ▁fellow ▁students ▁and ▁share ▁their ▁" res earch " ▁find ings ▁in ▁the ▁class ▁on ▁topics ▁r anging ▁from ▁d ating ▁and ▁home work ▁to ▁gain ing ▁the ▁F resh man ▁ 1 5 ▁and ▁trying ▁to ▁avoid ▁par king ▁tick ets . ▁He ▁has ▁also ▁taught ▁N ut r itional ▁Sciences ▁and ▁To xic ology ▁ 1 1 3 , ▁which ▁focus es ▁on ▁food ▁micro bi ology . ▁ ▁In vol vement ▁with ▁Student ▁Life ▁During ▁the ▁ 1 9 8 0 s , ▁Ch ang ▁served ▁on ▁the ▁campus ' s ▁Mas lach ▁Commission , ▁which ▁made ▁recommend ations ▁on ▁impro ving ▁under grad u ates ' ▁time ▁at ▁Ber