Concentration gradient
Thaum muaj qhov sib txawv ntawm cov kev daws teeb meem ntawm ob sab ntawm lub interface, nyob rau hauv qhov xwm txheej uas lub interface tso cai rau cov kev daws teeb meem mus dhau qhov kev ywj pheej, kev faib tawm ntawm cov ntsiab lus ntawm cov khes mis ntawm qhov siab concentration sab thiab qis concentration sab yog uniformly txo. Qhov ua rau ntu ntawm qhov siab txawv ntawm qhov no yog hu ua Yog cov concentration gradient.