We have studied the principles that govern the formation and dissociation of an adhesive bond between a cell moving in shear flow and a substrate and tested different theories of how force affects bond dissociation. Viscosity relates the kinematics of fluid movement (shear rate, units of time(-1)) to shear stress (units of force/area, the product of shear rate and viscosity). At different mediu...

The topology of self-assembled surfactant solutions includes varying degrees of micellar branching, ranging from linear wormlike micelles to a micellar network. Micellar branching acts as an effective attraction between micelles such that network condensation can lead to phase separation. Unlike chemical branching in polymers, micellar branches are labile. Movement of branches along a micelle c...

Suspensions of fumed silica in polypropylene glycol exhibit shear-thickening under steady shear and "strain-thickening" under oscillatory shear. Strain-thickening refers to a sharp increase in the complex viscosity eta* observed at critical combinations of strain-amplitude and frequency. Two regimes of strain-thickening behavior have been found: The first occurs at high critical strains and low...

The shear viscosity of the quark-gluon plasma is predicted to be lower than the collisional viscosity for weak coupling. The estimated ratio of the shear viscosity to entropy density is rather close to the ratio calculated by N = 4 super Yang–Mills theory for strong coupling, which indicates that the quark-gluon plasma might be strongly coupled. However, in the presence of momentum anisotropy, ...

We measure the shear viscosity in a two-component Fermi gas of atoms, tuned to a broad s-wave collisional (Feshbach) resonance. At resonance, the atoms strongly interact and exhibit universal behavior, where the equilibrium thermodynamic properties and transport coefficients are universal functions of density n and temperature T . We present a new calibration of the temperature as a function of...

The rheology of milk powder suspensions is investigated up to very high concentrations, where structural arrest occurs. The main component of the milk powder investigated is casein, so that the suspensions can be regarded as casein suspensions. Four concentration regimes are identified. For effective casein volume fractions less than 0.54 the concentration dependence of the zero-shear viscosity...

One of the room temperature ionic liquids (RTILs), 1-butyl-3-methylimidazolium chloride ([BMIM]Cl) was chosen to prepare the concentrated solutions of Polyacrylonitrile (PAN). The rheological behaviors of the solutions were measured with rotational rheometry under different conditions, including temperatures, concentration, and molecular weight of PAN. The solutions exhibited shear-thinning beh...

The Doi theory (J. Polym. Sci., Polym. Phys. Ed. 1981,19, 229) of concentrated solutions of rodlike particles is compared with the recent treatment of Bahar and Erman (J . Polym. Sci., Polym. Phys. Ed. 1986,24,1361) of the lattice theory of rods in a potential flow field. The Doi theory is modified by introducing a flow term to its effective mean-field potential, similar to that of the lattice ...

Measurements of rod climbing in A1 give rise to an apparent linear relation between the height rise h and the angular velocity Ω of the rod. We use a White-Metzner model to fit the data and we find that the height rise on the rod deviates from the quadratic dependence on the angular velocity when the viscosity or relaxation time vary with shear rate. When both the relaxation time and the viscos...