Direct observation of orientation distributions of actin filaments in a solution undergoing shear banding.
Shear banding is frequently observed in complex fluids. However, the configuration of macromolecules in solutions undergoing shear banding has not yet been directly observed. In this study, by using the fact that F-actin solutions exhibit shear banding and actin filaments are visualized by fluorescent labels, we directly observed the intrinsic states of an actin solution undergoing shear banding. By combining the 3D imaging of labeled actin filaments and particle image velocimetry (PIV), we obtained orientation distributions of actin filaments in both high and low shear rate regions, whose quantitative differences are indicated. In addition, by using the orientation distributions and applying stress expression for rod-like polymers, we estimated stress tensors in both high and low shear rate regions. This evaluation indicates that different orientation distributions of filamentous macromolecules can exhibit a common shear stress.
Research Institute for Electronic Science, Hokkaido University, Sapporo 001-0020, Japan.
K
http://orcid.org/0000-0003-1001-4599
K
Sato
Department of Information Engineering, Faculty of Engineering, University of the Ryukyus, 1 Senbaru, Nishihara, Okinawa 903-0213, Japan.
I
I
Kunita
Department of Physics, Ritsumeikan University, Noji-Higashi 1-1-1, Kusatsu, 525-8577, Japan.
Y
Y
Takikawa
Division of Applied Physics, Faculty of Engineering, Hokkaido University, N13W8, Sapporo 060-8628, Japan. orihara@eng.hokudai.ac.jp.
D
D
Takeuchi
Graduate School of Environment and Information Science, Yokohama National University, Tokiwadai 79-7, Hodogaya, Yokohama 240-850, Japan.
Y
Y
Tanaka
Research Institute for Electronic Science, Hokkaido University, Sapporo 001-0020, Japan.
T
T
Nakagaki
Division of Applied Physics, Faculty of Engineering, Hokkaido University, N13W8, Sapporo 060-8628, Japan. orihara@eng.hokudai.ac.jp.
H
http://orcid.org/0000-0003-4789-1632
H
Orihara