Write the postulated 2k factorial models for the following two practical experimental cases:

(1) Studying the growth of epitaxial layer on silicon wafer by chemical vapor deposition (CVD), where the response of interest, the epitaxial layer thickness, Y , is believed to depend on two primary factors: depo- sition time, x1, and arsenic ?ow rate, x2.

(2) Characterizing the solubility, Y , of a globular protein as a func- tion of three primary factors: pH, x1 ; salt concentration, x2 ; and tem- perature, x3.