Fig. 5. Dependence of total ion current (IC) signals on (A) mass or (B) area of cattle C1 feces in the chamber. To increase the total IC signal, cattle C1 feces was stored overnight at 37°C and subsequently at 20°C for 2 wk. Fiber exposure time = 5 min; flow rate = 1 L min^–1 (16 cm s^–1); chamber temperature = 20°C.