The Experts below are selected from a list of 231066 Experts worldwide ranked by ideXlab platform
Hajime Tanaka - One of the best experts on this subject based on the ideXlab platform.
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Fracture Phase Separation.
Physical review letters, 2009Co-Authors: Takehito Koyama, Takeaki Araki, Hajime TanakaAbstract:Here we report novel Phase-Separation behavior accompanying mechanical fracture ("fracture Phase Separation"), which is observed in polymer solutions. Surprisingly, mechanical fracture becomes a dominant coarsening process of the Phase Separation. The transition from viscoelastic to fracture Phase Separation corresponds to the "ductile-to-brittle transition" in fracture of materials under shear deformation. The only difference between fracture Phase Separation and material fracture is whether the deformation is induced internally by Phase Separation itself or externally by loading. This suggests a general physical scenario of mechanical selection of the kinetic pathway of inhomogeneization of materials under stress.
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Viscoelastic Phase Separation of protein solutions.
Physical review letters, 2005Co-Authors: Hajime Tanaka, Yuya NishikawaAbstract:In addition to the known behavior of normal Phase Separation and gelation, we report novel Phase-Separation behavior of protein solutions as their intermediate case. A network structure of the protein-rich Phase may be formed even if it is the minority Phase, contrary to the conventional wisdom. This behavior is characteristic of viscoelastic Phase Separation found in polymer solutions. This kinetic pathway may play crucial roles in the complex Phase ordering of protein solutions, in particular, protein network formation in biological systems and foods.
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Network formation in viscoelastic Phase Separation
Journal of Physics: Condensed Matter, 2002Co-Authors: Hajime Tanaka, Takehito Koyama, Takeaki ArakiAbstract:Viscoelastic Phase Separation is a new type of Phase Separation, which may be universal in any dynamically asymmetric mixture composed of slow and fast components. In such a dynamically asymmetric mixture, Phase Separation generally leads to the formation of a long-lived 'interaction network' (transient gel) of the slow components if the concentration is high enough and the attractive interactions between the components are strong enough. Then, domains rich in fast components are nucleated in a transient gel and they grow. Transiently, a network pattern of the Phase rich in slow components is produced even if it is a minority Phase. This is a unique feature of viscoelastic Phase Separation. Pattern evolution is basically controlled by the nucleation kinetics of domains rich in fast components under elastic interactions, the volume shrinking kinetics and the self-induced elastic stress. We discuss the roles of bulk and shear stresses on pattern formation and the mechanisms of network formation.
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Viscoelastic Phase Separation
Journal of Physics: Condensed Matter, 2000Co-Authors: Hajime TanakaAbstract:Descriptions of Phase Separation in condensed matter have so far been classified into a solid model (model B) and a fluid model (model H). In the former the diffusion is the only transport process, while in the latter material can be transported by both diffusion and hydrodynamic flow. It has recently been found that in addition to these well-known models a new model of Phase Separation, the `viscoelastic model', is required to describe the Phase-Separation behaviour of a dynamically asymmetric mixture, which is composed of fast and slow components. Such `dynamic asymmetry' can be induced by either the large size difference or the difference in glass-transition temperature between the components of a mixture. The former often exists in so-called complex fluids, such as polymer solutions, micellar solutions, colloidal suspensions, emulsions and protein solutions. The latter, on the other hand, can exist in any mixture in principle. This new type of Phase Separation is called `viscoelastic Phase Separation' since viscoelastic effects play a dominant role. Viscoelastic Phase Separation may be a `general' model of Phase Separation, which includes solid and fluid models as special cases: for example, fluid Phase Separation described by model H, which is believed to be the usual case, can be viewed as a `special' (rather rare) case of viscoelastic Phase Separation. Here we review the experiments, theories and numerical simulations for viscoelastic Phase Separation. In dynamically asymmetric mixtures, Phase Separation generally leads to the formation of a long-lived `interaction network' (a transient gel) of slow-component molecules (or particles), if the attractive interactions between them are strong enough. Because of its long relaxation time, it cannot catch up with the deformation rate of the Phase Separation itself and as a result the stress is asymmetrically divided between the components. This leads to the transient formation of networklike or spongelike structures of a slow-component-rich Phase and its volume shrinking. Domain shape is determined by the force-balance condition in this intermediate stage. However, the true late stage of this Phase Separation can be described by a fluid model. The process can be viewed as viscoelastic relaxation in pattern formation. We discuss the morphological and kinetic features of viscoelastic Phase Separation, focusing on the differences from those of usual Phase Separation. The significance of viscoelastic Phase Separation in pattern formation in Nature and its engineering applications are also pointed out.
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Viscoelastic Phase Separation and Transient Formation of Spongelike Patterns
Molecular Interactions and Time-Space Organization in Macromolecular Systems, 1999Co-Authors: Hajime TanakaAbstract:It has so far been believed that Phase Separation in isotropic condensed matter can be classified into either solid or fluid models, including some modification due to elastic effects. Contrary to this common belief, we recently found unusual Phase Separation, which can be described by neither of the above models, in a mixture whose components have a large difference in their dynamics. Thus, we proposed that a new model of Phase Separation, namely, “viscoelastic model”, is necessary to describe Phase Separation in such dynamically asymmetric mixtures. This model is likely a general model that can describe all types of isotropic Phase Separation including solid and fluid model as special cases. Viscoelastic Phase Separation in dynamically asymmetric mixtures can be characterized by the order-parameter switching phenomena: The primary order parameter switches from the composition to the deformation tensor as in gel, and back to the composition again, reflecting viscoelastic relaxation between a characteristic deformation time of Phase Separation and the slowest rheological time of the system. This unusual behavior can be explained by the above general nature of a viscoelastic model. It is remarkable that orderparameter switching can occur even during an ordering process driven by a ‘single’ thermodynamic driving force. We argue that spongelike patterns observed in Phase Separation of many materials may be produced by a common physical mechanism of viscoelastic Phase Separation. For example, spongelike patterns formed during polymerization-induced Phase Separation can also be explained by our viscoelastic model.
E. P. Yukalova - One of the best experts on this subject based on the ideXlab platform.
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Mesoscopic Phase Separation in anisotropic superconductors
Physical Review B, 2004Co-Authors: Vyacheslav I. Yukalov, E. P. YukalovaAbstract:The general properties of anisotropic superconductors with mesoscopic Phase Separation are analyzed. The main conclusions are as follows: Mesoscopic Phase Separation can be thermodynamically stable only in the presence of repulsive Coulomb interactions. Phase Separation enables the appearance of superconductivity in a heteroPhase sample even if it were impossible in pure-Phase matter. Phase Separation is crucial for the occurrence of superconductivity in bad conductors. The critical temperature for a mixture of pairing symmetries is higher than the critical temperature related to any pure gap-wave symmetry of this mixture. In bad conductors, the critical temperature as a function of the superconductivity fraction has a bell shape. Phase Separation makes the single-particle energy dispersion softer. For planar structures Phase Separation suppresses $d$-wave superconductivity and enhances $s$-wave superconductivity. These features are in agreement with experiments for cuprates.
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Superconductors with Mesoscopic Phase Separation
arXiv: Superconductivity, 1997Co-Authors: A. J. Coleman, E. P. Yukalova, Vyacheslav I. YukalovAbstract:A model of superconductivity is proposed taking into account repulsive particle interaction, mesoscopic Phase Separation and softening of crystalline lattice. These features are typical of many high-temperature superconductors. The main results obtained for the model are: (i) Phase Separation is possible only if repulsive forces play a significant role; (ii) the critical temperature as a function of the superconducting Phase fraction can have non-monotonic behaviour; (iii) superconductivity is possible in heteroPhase systems even when it would be forbidden in pure samples. These results are in agreement with experiments.
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Superconductors with mesoscopic Phase Separation
Physica C-superconductivity and Its Applications, 1995Co-Authors: A. J. Coleman, E. P. Yukalova, Vyacheslav I. YukalovAbstract:Abstract A model of superconductivity is proposed taking into account repulsive particle interaction, mesoscopic Phase Separation and softening of the crystalline lattice. These features are typical of many high-temperature superconductors. The main results obtained for the model are: (1) Phase Separation is possible only if repulsive forces play a significant role; (2) the critical temperature as a function of the superconducting Phase fraction can have non-monotonic behaviour; (3) superconductivity is possible in heteroPhase systems even when it would be forbidden in pure samples. These results are in agreement with experiments.
Vyacheslav I. Yukalov - One of the best experts on this subject based on the ideXlab platform.
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Mesoscopic Phase Separation in anisotropic superconductors
Physical Review B, 2004Co-Authors: Vyacheslav I. Yukalov, E. P. YukalovaAbstract:The general properties of anisotropic superconductors with mesoscopic Phase Separation are analyzed. The main conclusions are as follows: Mesoscopic Phase Separation can be thermodynamically stable only in the presence of repulsive Coulomb interactions. Phase Separation enables the appearance of superconductivity in a heteroPhase sample even if it were impossible in pure-Phase matter. Phase Separation is crucial for the occurrence of superconductivity in bad conductors. The critical temperature for a mixture of pairing symmetries is higher than the critical temperature related to any pure gap-wave symmetry of this mixture. In bad conductors, the critical temperature as a function of the superconductivity fraction has a bell shape. Phase Separation makes the single-particle energy dispersion softer. For planar structures Phase Separation suppresses $d$-wave superconductivity and enhances $s$-wave superconductivity. These features are in agreement with experiments for cuprates.
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Superconductors with Mesoscopic Phase Separation
arXiv: Superconductivity, 1997Co-Authors: A. J. Coleman, E. P. Yukalova, Vyacheslav I. YukalovAbstract:A model of superconductivity is proposed taking into account repulsive particle interaction, mesoscopic Phase Separation and softening of crystalline lattice. These features are typical of many high-temperature superconductors. The main results obtained for the model are: (i) Phase Separation is possible only if repulsive forces play a significant role; (ii) the critical temperature as a function of the superconducting Phase fraction can have non-monotonic behaviour; (iii) superconductivity is possible in heteroPhase systems even when it would be forbidden in pure samples. These results are in agreement with experiments.
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Superconductors with mesoscopic Phase Separation
Physica C-superconductivity and Its Applications, 1995Co-Authors: A. J. Coleman, E. P. Yukalova, Vyacheslav I. YukalovAbstract:Abstract A model of superconductivity is proposed taking into account repulsive particle interaction, mesoscopic Phase Separation and softening of the crystalline lattice. These features are typical of many high-temperature superconductors. The main results obtained for the model are: (1) Phase Separation is possible only if repulsive forces play a significant role; (2) the critical temperature as a function of the superconducting Phase fraction can have non-monotonic behaviour; (3) superconductivity is possible in heteroPhase systems even when it would be forbidden in pure samples. These results are in agreement with experiments.
Yuya Nishikawa - One of the best experts on this subject based on the ideXlab platform.
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Viscoelastic Phase Separation of protein solutions.
Physical review letters, 2005Co-Authors: Hajime Tanaka, Yuya NishikawaAbstract:In addition to the known behavior of normal Phase Separation and gelation, we report novel Phase-Separation behavior of protein solutions as their intermediate case. A network structure of the protein-rich Phase may be formed even if it is the minority Phase, contrary to the conventional wisdom. This behavior is characteristic of viscoelastic Phase Separation found in polymer solutions. This kinetic pathway may play crucial roles in the complex Phase ordering of protein solutions, in particular, protein network formation in biological systems and foods.
Kevin E. Kinzer - One of the best experts on this subject based on the ideXlab platform.
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Microporous membrane formation via thermally-induced Phase Separation. II: Liquid-liquid Phase Separation
Journal of Membrane Science, 1991Co-Authors: Douglas R. Lloyd, Sung Soo Kim, Kevin E. KinzerAbstract:Abstract Microporous membranes have been prepared via thermally-induced liquid—liquid Phase Separation of isotactic polypropylene—n,n bis (2-hydroxyethyl) tallowamine mixtures. The thermally-induced Phase Separation process is discussed in terms of the thermodynamics of the binary mixture and possible Phase Separation mechanisms. It is demonstrated that membranes can be produced by liquid—liquid Phase Separation followed by solidification of the polymer or by solid—liquid Phase Separation.
