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名古屋大学理学部物理学科R研の川崎猛史と申します。
当研究室では、下記のセミナー（2件）を予定しております。
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(1件目)
日時
2019年5月21日(火) 14:00～16:00
タイトル
Glassy dynamics of a model of bacterial cytoplasm with metabolic
activities [1]
講演者
大山倫弘氏 (産総研)
場所
東山キャンパス理学館 5F 506号室
アブストラクト
Recent experiments have revealed that cytoplasms become glassy when
their metabolism is suppressed, while they maintain fluidity in a living
state [2]. The mechanism of this active fluidization is not clear,
especially for bacterial cytoplasms [2,3], since they lack traditional
motor proteins, which can be described by conventional active matter
models, self-propelled particles [4]. We introduce a model of bacterial
cytoplasm focusing on the impact of conformational change in proteins
due to metabolic activities. In the model, proteins are treated as
particles under thermal agitation, and conformation changes are treated
as changes in particle volume. Simulations revealed that only a small
change in volume (~6%) fluidizes the glassy state, accompanied by a
change in fragility from fragile to strong, as reported experimentally
[2].
References:
[1] N. O., T. Kawasaki, H. Mizuno, A. Ikeda, arXiv: 1904.09052 (2019)
[2] K. Nishizawa et al., Sci. Rep. 7:15143 (2017)
[3] B. R. Parry et al., Cell 156, 183 (2014)
[4] M. C. Marchetti et al. Rev. Mod. Phys. (2013)
(2件目)
日時
2019年5月28日(火) 15:00～17:00
タイトル
Divergence of Viscosity underlying Enhanced Fluctuations in 2D
Glass-Forming Liquid
講演者
芝隼人氏 (東北大学)
場所
東山キャンパス理学館 5F 506号室
アブストラクト
If a liquid is cooled rapidly to form a glass, its structural relaxation
becomes retarded, producing a drastic increase in viscosity. In two
dimensions, strong long-wavelength fluctuations persist, even at low
temperature, making it difficult to evaluate the microscopic structural
relaxation time. In this talk, we show that relative displacement
between neighbor particles (so-called cage-relative displacement) yields
a relaxation time growing proportionally to the viscosity in a 2D
glass-forming liquid. Furthermore, in addition to thermal elastic
vibrations, diffusive relaxation of long-wavelength hydrodynamic
fluctuations also affects the dynamics to yield a logarithmically
divergence of diffusion coefficients in the long-time limit.
References:
H. Shiba, T. Kawasaki, and K. Kim, arXiv:1905.05458 (2019).
--
----------
Takeshi Kawasaki, Ph.D.
Assistant Professor
Department of Physics, Nagoya University,
Nagoya 464-8602, Japan
Tel/Fax: +81-52-789-2438
E-mail Address: kawasaki@r.phys.nagoya-u.ac.jp
URL: http://www.r.phys.nagoya-u.ac.jp/~kawasaki/index.html