Figure 4.

Rheological behavior of ND-mucin solutions. (A) Comparison of the storage moduli, G′ (ω) of 10 ≤ c ≤ 50 mg/mL ND-mucin. For concentrations below 10 mg/mL, the oscillatory spectra were within the standard error from that of pure buffer. (B) The loss tangent (tan δ), a ratio of the loss modulus (G″) to storage modulus (G′) of 10 ≤ c ≤ 50 mg/mL ND-mucin. (C) Steady shear viscosity, η, and complex viscosity, |η*|, of 10 ≤ c ≤ 50 mg/mL ND-mucin versus shear rate, $\dot{\gamma }$ and angular frequency, ω, measured using parallel-plate geometry at a gap of 40 μm. Insert shows the plot of shear stress, σ, versus shear rate, $\dot{\gamma }$, of the same data. (D) Parameters of the Herschel-Bulkley equation; yield stress σ₀ and consistency index K_HB, evaluated as best fits to the shear stress, σ, versus shear rate, $\dot{\gamma }$, of 10 ≤ c ≤ 50 mg/mL ND-mucin. The flow index, n, had a mean value of 0.73 (SD ± 0.02).