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. 2011 May 17;2:312. doi: 10.1038/ncomms1321

Figure 4. Yield stress measurement.

Figure 4

Steady rotation at 5 Hz (a), 10 Hz (b), and 30 Hz (c) divides the monolayer into two regions: an inner region that flows with the microbutton, deforms continuously and appears domain-free; and an outer region with domains that does not deform significantly. The radius RY of the yielded region (white arrows) is set by the surface yield stress, τsY. A torque balance gives Tapp=2πRY2τsY, consistent with (d); the slope gives τsY∼10−2 μN m−1, ∼Gs(ω)/10 (Fig. 2) as expected by analogy with three-dimensional emulsions5,28,29 (scale bar, 20 μm).