２０１７年２月１４日 Dr. Ankita Pandey （終了）
日時：２０１７年２月１４日（火） １４：３０〜１６：００
場所：首都大学東京 ８号館３００号室
講師：Dr. Ankita Pandey (名古屋大学)
題目：Flow-induced nonequilibrium self-assembly in suspensions of stiff, apolar, active filaments
要旨：Chemomechanically active filaments, composed of elements that convert chemical energy to mechanical motion, occur in many biological and biomimetic contexts. Here we study the hydrodynamics of a suspension of stiff apolar active filaments, with a permanent distribution of stresslets along its length, using the lattice Boltzmann method. These stiff active filaments cannot translate or rotate in isolation (and hence are apolar) but do so in the collective fluid flow of other filaments. Lateral hydrodynamic attractions in extensile filaments lead, independent of volume fraction, to anisotropic aggregates which translate and rotate. Lateral hydrodynamic repulsions in contractile filaments lead to microstructured states, where the degree of clustering increases with volume fraction and the filament motion is always diffusive. Our results demonstrate that the interplay of active hydrodynamic flows and anisotropic excluded volume interactions provides a generic non-equilibrium mechanism for hierarchical self-assembly of active soft matter.
[1] Ankita Pandey, P. B. Sunil Kumar, R. Adhikari, Soft Matter 12, 9068 (2016).
２０１７年２月１日 Prof. Haim Diamant （終了）
日時：２０１７年２月１日（水） １４：３０〜１６：００
場所：首都大学東京 ８号館３０７号室
講師：Prof. Haim Diamant（Tel Aviv University, Israel）
題目：Screening, hyperuniformity, and instability in the sedimentation of irregular objects
要旨：We study the overdamped sedimentation of non-Brownian objects of irregular shape using fluctuating hydrodynamics. The anisotropic response of the objects to flow, caused by their tendency to align with gravity, directly suppresses concentration and velocity fluctuations. This allows the suspension to avoid the anomalous fluctuations predicted for suspensions of symmetric spheroids. The suppression of concentration fluctuations leads to a correlated, hyperuniform structure. For certain object shapes, the anisotropic response may act in the opposite direction, destabilizing uniform sedimentation.
International Workshop on Hydrodynamic Flows in/of Cells （終了）
Date: 24 - 25 November, 2016
Place: Tokyo Metropolitan University,
Building 11, Room 202 (Nov. 24)
Building 8, Room 212 (Nov. 25)
Program:
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24 November (Thursday)
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13:00 - 14:00 Yusuke T. Maeda (Kyushu University)
Hydrodynamics and enzymatic reaction in moving thermal gradients
14:15 - 15:15 Nariya Uchida (Tohoku University)
Some applications of Smoothed Profile Method for active flow in and out of cells
15:30 - 16:30 Akatsuki Kimura (National Institute of Genetics)
The mechanism of cytoplasmic streaming in the Caenorhabidits elegans embryo
16:45 - 17:45 Natsuhiko Yoshinaga (Tohoku University)
The hydrodynamic interaction and collective behaviors of self-propelled particles and drops
18:00 - 19:00 poster
19:00 dinner
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25 November (Friday)
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9:45 - 10:45 Shuji Fujii (Hokkiado University)
Nuclear dynamics revealed by bio-tracers
11:00 - 12:00 Shigeyuki Komura (Tokyo Metropolitan University)
Anomalous diffusion in active cells
12:00 - 13:00 lunch
13:00 - 14:00 Daisuke Mizuno (Kyushu University)
Non-Gaussian glassy dynamics in living cells and cytoskeletons
14:15 - 15:15 Takeshi Ooshida (Tottori University)
Analytical treatment of collective motion in colloidal liquids
15:30 - 16:30 Hiroyuki Kitahata (Chiba University)
Hydrodynamic collective effects of active proteins in biological membranes
16:45 - 17:45 Alexander S. Mikhailov (Fritz-Haber-Institut der
Max-Planck-Gesellschaft)
There will be a poster session on Thursday evening. If you are interested in presenting a poster, please send the title and authors (affiliation) of your poster to S. Komura.
２０１６年１０月２７日 Dr. David Lacoste （終了）
日時： ２０１６年１０月２７日（木）１６：３０〜１８：００
場所： 首都大学東京 ８号館３０２号室
講師： Dr. David Lacoste（ESPCI, France）
題目： Shape matters in protein mobility within membranes
要旨：Lateral Brownian diffusion of proteins in lipid membranes has been predicted by Saffman and Delbruck to depend only on protein size and on the viscosity of the membrane and of the surrounding medium. Using a single-molecule tracking technique on two transmembrane proteins that bend the membrane differently and are reconstituted in giant unilamellar vesicles, we show that the mobility of a membrane protein is crucially dependent on the local membrane deformation self-generated around the protein, which can be tuned by adjusting membrane tension [1]. The feedback between membrane shaping and mobility is well explained by analytical and numerical models that include the friction of the deformed membrane patch with the surrounding medium and the friction internal to the bilayer. Extensions of this framework to other types of coupling between the membrane and the protein will be discussed [2].
[1] F. Quemeneur, J. K. Sigurdsson, M. Renner, P. J. Atzberger, P. Bassereau, and D. Lacoste, PNAS 111, 5083 (2014).
[2] V. Demery and D. Lacoste, chapter in book "Physics of biological membranes", published by Springer Netherlands.
