The Experts below are selected from a list of 56763 Experts worldwide ranked by ideXlab platform
Masanori Takaoka - One of the best experts on this subject based on the ideXlab platform.
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single wave number representation of nonlinear Energy spectrum in elastic wave turbulence of the foppl von karman equation Energy decomposition analysis and Energy budget
Physical Review E, 2014Co-Authors: Naoto Yokoyama, Masanori TakaokaAbstract:A single-wave-number representation of a nonlinear Energy spectrum, i.e., a stretching-Energy spectrum, is found in elastic-wave turbulence governed by the Foppl-von Karman (FvK) equation. The representation enables Energy decomposition analysis in the wave-number space and analytical expressions of detailed Energy budgets in the nonlinear interactions. We numerically solved the FvK equation and observed the following facts. Kinetic Energy and Bending Energy are comparable with each other at large wave numbers as the weak turbulence theory suggests. On the other hand, stretching Energy is larger than the Bending Energy at small wave numbers, i.e., the nonlinearity is relatively strong. The strong correlation between a mode a(k) and its companion mode a(-k) is observed at the small wave numbers. The Energy is input into the wave field through stretching-Energy transfer at the small wave numbers, and dissipated through the quartic part of kinetic-Energy transfer at the large wave numbers. Total-Energy flux consistent with Energy conservation is calculated directly by using the analytical expression of the total-Energy transfer, and the forward Energy cascade is observed clearly.
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single wave number representation of nonlinear Energy spectrum in elastic wave turbulence of the foppl von karman equation Energy decomposition analysis and Energy budget
Physical Review E, 2014Co-Authors: Naoto Yokoyama, Masanori TakaokaAbstract:A single-wave-number representation of a nonlinear Energy spectrum, i.e., a stretching-Energy spectrum, is found in elastic-wave turbulence governed by the F\"oppl--von K\'arm\'an (FvK) equation. The representation enables Energy decomposition analysis in the wave-number space and analytical expressions of detailed Energy budgets in the nonlinear interactions. We numerically solved the FvK equation and observed the following facts. Kinetic Energy and Bending Energy are comparable with each other at large wave numbers as the weak turbulence theory suggests. On the other hand, stretching Energy is larger than the Bending Energy at small wave numbers, i.e., the nonlinearity is relatively strong. The strong correlation between a mode ${a}_{\mathbit{k}}$ and its companion mode ${a}_{\ensuremath{-}\mathbit{k}}$ is observed at the small wave numbers. The Energy is input into the wave field through stretching-Energy transfer at the small wave numbers, and dissipated through the quartic part of kinetic-Energy transfer at the large wave numbers. Total-Energy flux consistent with Energy conservation is calculated directly by using the analytical expression of the total-Energy transfer, and the forward Energy cascade is observed clearly.
Xiaoqiang Wang - One of the best experts on this subject based on the ideXlab platform.
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efficient and stable exponential time differencing runge kutta methods for phase field elastic Bending Energy models
Journal of Computational Physics, 2016Co-Authors: Xiaoqiang WangAbstract:The Willmore flow formulated by phase field dynamics based on the elastic Bending Energy model has been widely used to describe the shape transformation of biological lipid vesicles. In this paper, we develop and investigate some efficient and stable numerical methods for simulating the unconstrained phase field Willmore dynamics and the phase field Willmore dynamics with fixed volume and surface area constraints. The proposed methods can be high-order accurate and are completely explicit in nature, by combining exponential time differencing Runge-Kutta approximations for time integration with spectral discretizations for spatial operators on regular meshes. We also incorporate novel linear operator splitting techniques into the numerical schemes to improve the discrete Energy stability. In order to avoid extra numerical instability brought by use of large penalty parameters in solving the constrained phase field Willmore dynamics problem, a modified augmented Lagrange multiplier approach is proposed and adopted. Various numerical experiments are performed to demonstrate accuracy and stability of the proposed methods.
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modelling and simulations of multi component lipid membranes and open membranes via diffuse interface approaches
Journal of Mathematical Biology, 2007Co-Authors: Xiaoqiang WangAbstract:Diffuse interface (phase field) models are developed for multi-component vesicle membranes with different lipid compositions and membranes with free boundary. These models are used to simulate the deformation of membranes under the elastic Bending Energy and the line tension Energy with prescribed volume and surface area constraints. By comparing our numerical simulations with recent biological experiments, it is demonstrated that the diffuse interface models can effectively capture the rich phenomena associated with the multi-component vesicle transformation and thus offering great functionality in their simulation and modelling.
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Simulating the deformation of vesicle membranes under elastic Bending Energy in three dimensions
Journal of Computational Physics, 2006Co-Authors: Chun Liu, Xiaoqiang WangAbstract:In this paper, we study the three-dimensional deformation of a vesicle membrane under the elastic Bending Energy, with prescribed bulk volume and surface area. Both static and dynamic deformations are considered. A newly developed energetic variational formulation is employed to give an effective Eulerian description. Efficient time and spatial discretizations are considered and implemented. Numerical experiments illustrate some fascinating phenomena that are of interests in real applications.
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Modeling the spontaneous curvature effects in static cell membrane deformations by a phase field formulation
Communications on Pure and Applied Analysis, 2005Co-Authors: Chun Liu, Rolf J. Ryham, Xiaoqiang WangAbstract:In this paper, we study the effects of the spontaneous curvature on the static deformation of a vesicle membrane under the elastic Bending Energy, with prescribed bulk volume and surface area. Generalizing the phase field models developed in our previous works, we deduce a new Energy formula involving the spontaneous curvature effects. Several axis-symmetric configurations are obtained through numerical simulations. Some analysis on the effects of the spontaneous curvature on the vesicle membrane shapes are also provided.
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a phase field formulation of the willmore problem
Nonlinearity, 2005Co-Authors: Chun Liu, Rolf J. Ryham, Xiaoqiang WangAbstract:In this paper, we demonstrate, through asymptotic expansions, the convergence of a phase field formulation to model surfaces minimizing the mean curvature Energy with volume and surface area constraints. Under the assumption of the existence of a smooth limiting surface, it is shown that the interface of a phase field, which is a critical point of the elastic Bending Energy, converges to a critical point of the surface Energy. Further, the elastic Bending Energy of the phase field converges to the surface Energy and the Lagrange multipliers associated with the volume and surface area constraints remain uniformly bounded. This paper is a first step to analytically justify the numerical simulations performed by Du, Liu and Wang in 2004 to model equilibrium configurations of vesicle membranes.
Naoto Yokoyama - One of the best experts on this subject based on the ideXlab platform.
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single wave number representation of nonlinear Energy spectrum in elastic wave turbulence of the foppl von karman equation Energy decomposition analysis and Energy budget
Physical Review E, 2014Co-Authors: Naoto Yokoyama, Masanori TakaokaAbstract:A single-wave-number representation of a nonlinear Energy spectrum, i.e., a stretching-Energy spectrum, is found in elastic-wave turbulence governed by the Foppl-von Karman (FvK) equation. The representation enables Energy decomposition analysis in the wave-number space and analytical expressions of detailed Energy budgets in the nonlinear interactions. We numerically solved the FvK equation and observed the following facts. Kinetic Energy and Bending Energy are comparable with each other at large wave numbers as the weak turbulence theory suggests. On the other hand, stretching Energy is larger than the Bending Energy at small wave numbers, i.e., the nonlinearity is relatively strong. The strong correlation between a mode a(k) and its companion mode a(-k) is observed at the small wave numbers. The Energy is input into the wave field through stretching-Energy transfer at the small wave numbers, and dissipated through the quartic part of kinetic-Energy transfer at the large wave numbers. Total-Energy flux consistent with Energy conservation is calculated directly by using the analytical expression of the total-Energy transfer, and the forward Energy cascade is observed clearly.
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single wave number representation of nonlinear Energy spectrum in elastic wave turbulence of the foppl von karman equation Energy decomposition analysis and Energy budget
Physical Review E, 2014Co-Authors: Naoto Yokoyama, Masanori TakaokaAbstract:A single-wave-number representation of a nonlinear Energy spectrum, i.e., a stretching-Energy spectrum, is found in elastic-wave turbulence governed by the F\"oppl--von K\'arm\'an (FvK) equation. The representation enables Energy decomposition analysis in the wave-number space and analytical expressions of detailed Energy budgets in the nonlinear interactions. We numerically solved the FvK equation and observed the following facts. Kinetic Energy and Bending Energy are comparable with each other at large wave numbers as the weak turbulence theory suggests. On the other hand, stretching Energy is larger than the Bending Energy at small wave numbers, i.e., the nonlinearity is relatively strong. The strong correlation between a mode ${a}_{\mathbit{k}}$ and its companion mode ${a}_{\ensuremath{-}\mathbit{k}}$ is observed at the small wave numbers. The Energy is input into the wave field through stretching-Energy transfer at the small wave numbers, and dissipated through the quartic part of kinetic-Energy transfer at the large wave numbers. Total-Energy flux consistent with Energy conservation is calculated directly by using the analytical expression of the total-Energy transfer, and the forward Energy cascade is observed clearly.
Thomas Zemb - One of the best experts on this subject based on the ideXlab platform.
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thermodynamic description of synergy in solvent extraction ii thermodynamic balance of driving forces implied in synergistic extraction
Langmuir, 2017Co-Authors: J Rey, Thomas Zemb, Michael Bley, Jeanfrancois Dufreche, Simon Gourdin, Stephane Pelletrostaing, Sandrine DourdainAbstract:In the second part of this study, we analyze the free Energy of transfer in the case of synergistic solvent extraction. This free Energy of the transfer of an ion in dynamic equilibrium between two coexisting phases is decomposed into four driving forces combining long-range interactions with the classical complexation free Energy associated with the nearest neighbors. We demonstrate how the organometallic complexation is counterbalanced by the cost in free Energy related to structural change on the colloidal scale in the solvent phase. These molecular forces of synergistic extraction are driven not only by the entropic term associated with the tight packing of electrolytes in the solvent and by the free Energy cost of coextracting water toward the hydrophilic core of the reverse aggregates present but also by the entropic costs in the formation of the reverse aggregate and by the interfacial Bending Energy of the extractant molecules packed around the extracted species. Considering the sum of the terms, we can rationalize the synergy observed, which cannot be explained by classical extraction modeling. We show an industrial synergistic mixture combining an amide and a phosphate complexing site, where the most efficient/selective mixture is observed for a minimal Bending Energy and maximal complexation Energy.
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correspondence between curvature packing parameter and hydrophilic lipophilic deviation scales around the phase inversion temperature
Langmuir, 2009Co-Authors: Werner Kunz, Fabienne Testard, Thomas ZembAbstract:We show in this paper that three ways of characterizing “spontaneous” lateral packing of amphiphiles are equivalent: the spontaneous curvature, the molecular packing parameter, and the refined hydrophilic−lipophilic balance known as HLD (hydrophilic−lipophilic deviation). Recognition of this equivalence, with its underlying hypothesis of incompressible fluid with lowest surface Energy, reinforces the single parameter Bending Energy expression implicit in the classical papers by Ninham and Israelachvili, as well as all the predictive models of solubilization developed as yet.
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determination of pore size of catanionic icosahedral aggregates
Langmuir, 2004Co-Authors: Karine Glinel, Monique Dubois, Jeanmarc Verbavatz, Gleb B Sukhorukov, Thomas ZembAbstract:We show that it is possible to measure the porosity of facetted micron-sized hollow icosahedra of catanionic solutions by performing fluorescence recovery after photobleaching measurements. The size of spontaneous permanent pores in bilayers formed via molecular segregation is compatible with what is observed by freeze-fracture electron microscopy and is discussed versus theoretical expressions of Bending Energy.
Iskander I. Ismailov - One of the best experts on this subject based on the ideXlab platform.
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Role of membrane curvature in mechanoelectrical transduction: ion carriers nonactin and valinomycin sense changes in integral Bending Energy.
Biochimica et Biophysica Acta (BBA) - Biomembranes, 2006Co-Authors: V. Gh Shlyonsky, V.s. Markin, Iraida E. Andreeva, Steen E. Pedersen, Sidney A. Simon, Dale J. Benos, Iskander I. IsmailovAbstract:We describe the phenomenon of mechanoelectrical transduction in macroscopic lipid bilayer membranes modified by two cation-selective ionophores, valinomycin and nonactin. We found that bulging these membranes, while maintaining the membrane tension constant, produced a marked supralinear increase in specific carrier-mediated conductance. Analyses of the mechanisms involved in mechanoelectrical transduction induced by the imposition of a hydrostatic pressure gradient or by an amphipathic compound chlorpromazine reveal similar changes in the charge carrier motility and carrier reaction rates at the interface(s). Furthermore, the relative change in membrane conductance was independent of membrane diameter, but was directly proportional to the square of membrane curvature, thus relating the observed phenomena to the bilayer Bending Energy. Extrapolated to biological membranes, these findings indicate that ion transport in cells can be influenced simply by changing shape of the membrane, without a change in membrane tension.