TY  - CONF
AU  - Kang, Kyongok
TI  - Shear-Induced Flow Profiles and Phases/States Induced by Electric Fields in Suspensions of Charged DNA-Viruses
PB  - SKKU, South Korea
M1  - FZJ-2023-03938
PY  - 2023
AB  - I will first briefly discuss the equilibrium phase diagram of fd-viruses as a function of their concentration and ionic strength, with an emphasis on very low ionic strengths [1,2]. These fd-virus particles are charged rod-like protein-coated DNA strands, with a length of 880 nm, a width of 6.8 nm, and a persistence length of about 2500 nm, and serve as a model system for highly charged, very long and thin, chiral rod-like colloids. At sufficiently low ionic strengths extensive chiral-mesophases and the glass state are found [3-5]. Subsequently I will discuss the response of concentrated fd-virus suspensions to shear flow and electric fields: (i) Applying shear flow in the vicinity of the glass transition and well within the glass state, several types of inhomogeneous flow profiles are found. Plug flow is observed at relatively low applied shear rates, which transits to a gradient shear-banded flow profile on increasing the shear rate, while at large shear rates the common linear flow profile is regained. These flow profiles coexist with vorticity Taylor-bands [6-8]. (ii) A number of new phases are induced when a suspension within the isotropic-nematic biphasic region (where nematic domains coexist with an isotropic suspension) is subjected to AC electric fields. Upon varying the electric field strength and frequency, the nematic domains become chiral-nematic domains, which persistently melt and reform at sufficiently high electric field strengths and sufficiently low frequencies, due to the dissociation/association of condensed ions. While, at high frequencies a homogeneous homeotropically aligned phase is to be stabilized by hydrodynamic interactions resulting from electro-osmotic flow [9-11]. The kinetics of the dynamical state where noematic domains persistently melt and reform is quantified by means of an image-time correlation (ITC), which can be applied to other morphology changes in time analysis [12-14]. *** References:1.	K. Kang, “Equilibrium phase diagram and thermal responses of charged DNA-virus rod-suspensions at low ionic strengths”, Sci. Rep. 11: 3472, 2021.2.	K. Kang, “Characterization of orientation correlation kinetics: chiral-mesophase domains in suspensions charged DNA-rods”, J. Phys. Commun., 6, 015001, 2022.3.	K. Kang, “Glass transition of repulsive charged rods (fd-viruses)”, Soft Matter, 10, 3311-3324, 2014.4.	K. Kang and J. K. G. Dhont, “Structural arrest and texture dynamics in suspensions of charged colloidal rods”, Soft Matter, 9, 4401-4411, 2013.5.	K. Kang and J. K. G. Dhont, “Glass transition in suspensions of charged rods: Structural arrest and texture dynamics”, Phys. Rev. Lett. 110, 015901, 2013.6.	K. Kang, “Response of shear in bulk orientations of charged DNA rods: Taylor- and Gradient-banding”, J. Phys. Commun, 5, 045011, 2021.7.	D. Parisi, D. Vlassopoulos, H. Kriegs, J. K. G. Dhont, and K. Kang, Underlying mechanism of shear-banding in soft glasses of charged colloidal rods with orientational domains, Journal of Rheology 66, 365, 2022.8.	J.K.G. Dhont, K. Kang, H. Kriegs, O. Danko, J. Marakakis, and D. Vlassopoulos, “Nonuniform flow in soft glasses of colloidal rods”, Phys. Rev. Fluids. 2, 043301, 2017.9.	K. Kang, and J. K. G. Dhont, “Electric-field induced transitions in suspensions of charged colloidal rods”, Soft Matter, 6, 273, 201010.	K. Kang, “Image time-correlation, dynamic light scattering and birefringence for the study of the response of anisometric colloids to external fields”, Rev. Sci. Instrum. 82, 053903, 2011.11.	K. Kang, “Charged fibrous viruses (fd) in external electric fields: dynamics and orientational order”, New Journal of Physics, 12, 063017, 2010.12.	K. Kang, S.H. Piao, and H.J. Choi, “Synchronized oscillations of dimers in biphasic charged fd-virus suspensions”, Phys. Rev. E., 94, 020602(R), 2016.13.	K. Kang, J.S. Hong, and J.K.G. Dhont, “Local interfacial migration of clay particles within an oil droplet in an aqueous environment”, J. Phys. Chem. C, 118, 24803-24810, 2014.14.	K. Kang, Y. Ma, and K. Sadakane, “Direct visualization of local activities of long DNA strands via image–time correlation”, European Biophysics Journal 50:1139–1155, 2021.
T2  - Invited talk
CY  - 18 Sep 2023 - 18 Sep 2023, SKKU Univ. (South Korea)
Y2  - 18 Sep 2023 - 18 Sep 2023
M2  - SKKU Univ., South Korea
LB  - PUB:(DE-HGF)31
UR  - https://juser.fz-juelich.de/record/1017116
ER  -