<<< Time Table >>> (updated 6/19/2013)
Friday (July 5th, 2013)
Pre-Poster Session / Coffee (10:00~11:30)
Poster Presentations.
Lunch (11:30~12:55)
0:Ryo Akiyama (Kyushu Univ., Japan)
Opening Remarks
(12:55~13:00)
1:T. Yagasaki(Okayama Univ.)
Liquid-liquid phase separation of water: A molecular dynamics study
(13:00~13:30)
2:L. Xu (Peking Univ.)
Understanding the anomalous phase behaviors of water
(13:30~14:00)
3:H.-D. Kim (Kyoto Univ.)
Semiquantum Molecular Dynamics Simulation of Liquid Water -Microscopic, Mesoscopic, and Macroscopic Dynamic Properties-
(14:00~14:30)
Coffee (14:30~14:45)
Poster Preview (14:45~15:15?)
Poster Session / Coffee (15:15~16:50)
Poster Presentations.
4:A. Chiba (Keio Univ.)
Search for polyamorphism and liquid-liquid transitions in polymers
(16:50~17:20)
5:J. O. Indekeu(Katholieke Univ. Leuven)
Renormalization group predictions for infinite-order wetting
(17:20~17:50)
Banquet (18:00~19:30)
Saturday (July 6th, 2013)
Coffee with Posters (9:00~9:30)
6:F. Zhang (Tuebingen Univ.)
Liquid-Liquid Phase Separation in Protein Solutions Induced by Multivalent Salts
(9:30~10:00)
7:R. Roth (Tuebingen Univ.)
Phase Behavior of Protein and Salt Mixtures
(10:00~10:30)
8:A. Yoshimori (Kyushu Univ.)
Control of solid phase stability by interaction potential with two minima
(10:30~11:00)
Coffee with Posters (11:00~11:15)
9:M. Yanagisawa (Kyushu Univ.)
Spontaneous patterning of gels by confining polymer mixture to microspheres
(11:15~11:45)
10:K. Koga (Okayama Univ.)
The osmotic second virial coefficient of hydrophobic solutes in aqueous solution
(11:45~12:15)
<<< Abstract >>>
A. Chiba (Keio Univ.)
Search for polyamorphism and liquid-liquid transitions in polymers
Abstract:
Amorphous-amorphous or liquid-liquid transitions are now well known. These are transitions (or continuous transformations) between two disordered structures, and the concept of such polymorphism in disordered systems is sometimes called “polyamorphism”. The polyamorphism is originally suggested experimentally for ice in 1985, and now is well known to be seen in materials such as SiO2, phosphorus, and so on. The important point is that it is characterized by changes in static structure S(Q). Here we did an in-situ search for a liquid-liquid transition in a polymer. High-pressure in situ x-ray diffraction and specific-volume measurements on isotactic poly(4-methyl-1-pentene) melt have uncovered abrupt changes in the pressure dependence of microscopic structure as well as that of macroscopic density. Although the change was found to be continuous, we found a clear change in the first sharp diffraction peak (FSDP) of S(Q). In other words, we observed two kinds of structures in the melted state of this polyolefin; i.e., low-density melt and high-density melt. We also have started to investigate the possibility of amorphous-amorphous transitions for the same polymer and also of such polyamorphism for other polymers. We shall give a brief review on polyamorphism and show our resent results.
pdf file
J. O. Indekeu(Katholieke Univ. Leuven), K. Koga(Okayama Univ.), H. Hooyberghs(Katholieke Univ. Leuven) and A.O. Parry(Imperial College London)
Renormalization group predictions for infinite-order wetting
Abstract:
We study the effect of thermal fluctuations on the wetting phase transitions of infinite order and of continuously varying order, recently discovered within a mean-field density-functional model for three-phase equilibria in systems with short-range forces and a two-component order parameter. Using linear functional renormalization group (RG) calculations within a local interface Hamilto- nian approach, we show that the infinite-order transitions are robust. The exponential singularity (implying 2 － αs = ∞) of the surface free energy excess at infinite-order wetting as well as the precise algebraic divergence (with βs = －1) of the wetting layer thickness are not modified as long as ω < 2, with ω the dimensionless wetting parameter that measures the strength of thermal fluc- tuations. The interface width diverges algebraically and universally (with ν⊥ = 1/2). In contrast, the non-universal critical wetting transitions of finite but continuously varying order are modified when thermal fluctuations are taken into account, in line with predictions from earlier calculations on similar models displaying weak, intermediate and strong fluctuation regimes.
pdf file
H.-D. Kim (Kyoto Univ.)
Semiquantum Molecular Dynamics Simulation of Liquid Water -Microscopic, Mesoscopic, and Macroscopic Dynamic Properties-
Abstract:
We have developed the new semiquantum water (SQW) molecular dynamics (MD) simulation method. Here, the wave packet (WP) approach was for the first time applied to study condensed bulk water structure and dynamics. In order to account for nuclear quantum effects such as the zero point energy and WP delocalization, we described each hydrogen atom as a three-dimensional Gaussian WP basis function. Our SQW MD simulation requires only the additional equations of motion for the WP width and its momenta, and the computational cost is much cheaper than other semiquantum approaches. Nevertheless, our SWQ simulation successfully reproduced the major properties of centroid MD and ring polymer MD, namely that quantized water is less structured, that the diffusion coefficient is larger than is seen in classical simulations, and that the IR spectrum of the OH stretching mode is red-shifted. Furthermore, we found a new peak above the OH stretching peak set which could be a direct observation of the hydrogen WP dynamics in the liquid water.
Our SQW MD simulation made it possible to directly view the WP dynamics in the liquid water, and demonstrated that WP dynamics play an important role in the the hydrogen-bond network (HBN) dynamics; e.g. the WP dynamics accelerates the memory loss of the HBN. We also found significant correlations between the WP dynamics and mesoscopic rearrangements of water molecules such as a cage breakout in liquid water.
pdf file
K. Koga (Okayama Univ.)
The osmotic second virial coefficient of hydrophobic solutes in aqueous solution
Abstract:
The osmotic second virial coefficient of small hydrophobic molecules in water is evaluated from the correlation-function integrals. It is found that the osmotic second virial coefficient of methane decreases with increasing temperature from 258 K to 373 K at atmospheric pressure, changing its sign in between 258 K and 298 K.
The trend is consistent with a view that the hydrophobic attraction is weak or absent at low temperatures and strong at high temperatures.
R. Roth (Tuebingen Univ.)
Phase Behavior of Protein and Salt Mixtures
Abstract:
Experimentally one finds a rich and interesting behavior of proteins
in solution, such as human serum albumin (HSA), when yttrium chlorid
is added. One finds for example cluster formation, a liquid-liquid
phase separation and crystallization.
Yttrium, which is trivalent in solution, can bind to the surface of
the protein and can induce highly directional so-called patchy
interactions between proteins. In this talk we introduce a model
system which allows us to understand the origin of the patchy
interaction between proteins and how this interaction affects the
phase behavior of the protein salt mixture. Several experimental
observations can be understood (at least qualitatively) with this
model.
T. Yagasaki(Okayama Univ.)
Liquid-liquid phase separation of water: A molecular dynamics study
Abstract:
Water is one of the most studied liquids because it has many peculiar properties. It is known that the isobaric heat capacity of water sharply increases with decreasing temperature down to 235 K. A leading hypothesis to explain this anomaly is the liquid-liquid phase transition theory. This theory attributes the divergent behavior of thermodynamic response functions to the hypothesized second critical point at Tc’ ~ 220 K. Although many computer simulations and experiments seem to support the liquid-liquid phase transition scenario, this is still a controversial issue.
The liquid-liquid phase transition hypothesis suggests that supercooled water exists as either a low density liquid (LDL) or high density liquid (HDL) for T < Tc’. If the system is at constant volume and the density is intermediate between those of the low and high density phases, a spontaneous phase separation is expected to occur at T ~ Tc’ in the course of decreasing temperature. To the best of our knowledge, however, there has been no study which clearly demonstrates the liquid-liquid phase separation of water, because of the fact that the two liquid phases are quite similar to each other and thus it is difficult to distinguish them.
To observe the liquid-liquid phase separation of water, we performed very long isochoric-isothermal (NVT) molecular dynamics simulations. We classified water molecules based on the hydrogen bond network rearrangement dynamics, and found that the liquid-liquid phase separation indeed takes place at temperatures below the second critical point. Our results strongly support the liquid-liquid phase transition hypothesis.
pdf file
M. Yanagisawa (Kyushu Univ.)
Spontaneous patterning of gels by confining polymer mixture to microspheres
Abstract:
Polymer gels show complex surface patterns upon volume phase transition in response to external stimuli. Here we report a spontaneous patterning of gels in binary polymer solution by confining to soft microspheres: water-in-oil (W/O) microdroplets coated with a lipid layer. We encapsulated gelatin/PEG (polyethylene glycol) solution in droplets, where liquid-liquid (L-L) phase separation proceeded and then gelation of gelatin trapped the coarsening process with decreasing temperature. Deep quench generated smaller domains of gels with various shapes like network, sponge, etc. Whereas, shallow quench completed L-L phase separation before the gelation, and brought a large mono-domain in gel wetting to the droplet surface. Below the gelation temperature, smaller droplets than a critical size deformed their shapes to minimize the interfacial area between gelatin/PEG phases. The shapes of gels were determined by a force balance among bending elasticity of gel, interfacial tensions between gelatin/PEG and W/O phases. We found that the gelation increased the interfacial tension between gelatin/PEG phases. Therefore, gelation resulted in transformation of smaller droplets with a larger area-to-volume ratio to minimize the gelatin/PEG interface area against the costs of bending energy of gel and interfacial energy at W/O surface. Furthermore, the spontaneous patterns of gels were varied by changing polymer compositions and lipid species coating the droplet surface. These results demonstrate the coupling between phase separation and gelatin of polymers in droplets generates a great variety of microgel patterns.
pdf file
A. Yoshimori (Kyushu Univ.)
Control of solid phase stability by interaction potential with two minima
Abstract:
We study phase stability of a double-minimum potential system to establish the relationship to the potential form of interaction between constituent particles. The present double-minimum potential is the Lennard-Jones-Gauss (LJG) potential, which has a Gaussian pocket as well as a standard Lennard-Jones minimum. We can change the depth and position of the Gaussian pocket by parameters of the potential. For the LJG potential system, the coexistence density and freezing pressure are calculated by the thermodynamic perturbation method. We split the LJG potential into hard-sphere reference and perturbation parts. By expansion of the perturbation part, we calculate the Helmholtz free energy of the system in the liquid and solid phases to draw common tangents. In the LJG potential, the position of the second minimum (Gaussian pocket) affects significantly the stability of the solid phase. There are positions providing large stability of fcc and bcc crystals. We can explain the reason for the large stability by relative positions of the second minimum (Gaussian pocket) to the crystal structure. The present study is also presented in the poster session.
L. Xu (Peking Univ.)
Understanding the anomalous phase behaviors of water
Abstract:
Water is one of the most abundant materials in the universe and affects every aspect of our life. The phase behavior of water is important for the understanding of some basic questions related to its anomalous behaviors such as density anomaly and unusual behavior of solubility. In this talk, I will present some of our studies on phase transitions associated with the anomalous behaviors in bulk and confined water-like systems. Our results based on the studies of the thermodynamic, dynamic, and structural properties of model systems are consistent with the experimental observations in water and provide a possible way for experiment to locate the liquid-liquid critical point buried in the deep supercooled region.
Reference: Proc. Natl. Acad. Sci. 102, 16558(2005); Nature Physics 5, 655(2009), Proc. Natl. Acad. Sci. 109, 13177(2012).
pdf file
F. Zhang (Tuebingen Univ.) (M. WOLF, F. ROOSEN-RUNGE, R. ROTH, F. ZHANG, F. SCHREIBER)
Liquid-Liquid Phase Separation in Protein Solutions Induced by Multivalent Salts
Abstract:
pdf file
7th Mini-Symposium on Liquids 準備委員会（甲賀、秋山）