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| Home > Publications database > Charged (Filamentous) DNA-viruses in External Electric Fields and Shear Flow |
| Conference Presentation (Invited) | FZJ-2022-04517 |
2022
Abstract: Bacteriophage DNA-viruses (fd) consist of a DNA strand that is covered by several thousands of fd-coat proteins. The 880 nm long DNA-virus is relatively stiff due to these coat proteins (the persistence length is about 2500 nm). In addition, the coat proteins render a DNA-virus highly charged, such that a large fraction of ions are condensed onto the core of the virus. By varying the ionic strength, the equilibrium phase behaviors are explored well for the stable chiral-mesophases, as well the field-induced new phases in non-equilibrium processes at ow AC electric fields and shear flow. I will address the response of concentrated DNA-virus suspensions to external electric fields (for suspensions in the two-phase isotropic-nematic coexistence region), and to externally applied shear flow (for crowded suspensions in the glassy state). Several phases and dynamical states are induced by electric fields, depending on the field strength and frequency, due to field-induced dissociation/association of condensed ions and hydrodynamic interactions thorugh field-induced electro-osmotic flow. Shear flow induces several kinds of inhomogeneous flow profiles. At low shear rates, the plug flow and fracture are observed, a transition to a shear-banded state is seen on increasing the shear rate, in coexistence with Taylor vorticity banding, while at high shear rates a homogeneously sheared profile is observed where the shear rate is constant throughout the gap of the shear cell. The above phenomena have been observed in bulk, with 1 mm thick cylindrical sample cells. It would be also interesting to investigate the effect of confinement in an arbitrary shape of curvatures, using microfluidic channel flows, allowing the gradients of different ionic strengths. In particular, the role of confinement in both field-induced dynamical states for small (chiral) nematic domains, and the shear-induced fracture in the glassy state can be further conveyed, to which extent the size of (chiral) nematic domains are affected by the dimensions in the confining geometry.
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