# Foaming properties Foam formation Solutions at w w xA ml

2.4. Foaming properties

2.4.1. Foam formation

Solutions at 2% w/w (30 ml) were foamed at room temperature in a graduated tube (3 cm diameter) for 3 min with Griffin & George stirrer at 200 rpm. Overrun was calculated as Foam Overrun (FO):equation(2)FO(%)=foam volume(ml)-30(ml)/30(ml)×100

The data reported Salinosporamide A means of at least two replicates. The error was 10%.

2.4.2. Foam drainage

The volume of liquid drained to the bottom of the graduated tubes and foam height decrease related to collapse, were recorded as a function of time. The following empirical mathematical model was applied to fit the drainage over time [4]:equation(3)v(t)=Vtn/c+tnv(t)=Vtn/c+tnwhere: v(t) was the volume drained at time t; V is cell cycle the maximum volume drained; n was a constant related to the sigmoid shape of the curves; and c was a constant related to drainage half time by c1/n. The rate constant for drainage (kdr) was calculated as:equation(4)kdr=n/Vc1/nkdr=n/Vc1/n

The data reported are means of at least two replicates. The error in kdr was 11%.