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Derek Y. C. Chan - One of the best experts on this subject based on the ideXlab platform.
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measuring forces and spatiotemporal evolution of thin water films between an air bubble and solid surfaces of different hydrophobicity
ACS Nano, 2015Co-Authors: Chen Shi, Derek Y. C. Chan, Xin Cui, Lei Xie, Qingxia Liu, Jacob N Israelachvili, Hongbo ZengAbstract:A combination of atomic force microscopy (AFM) and reflection interference contrast microscopy (RICM) was used to measure simultaneously the Interaction force and the spatiotemporal evolution of the thin water film between a bubble in water and mica surfaces with varying degrees of hydrophobicity. Stable films, supported by the repulsive van der Waals–Casimir–Lifshitz force were always observed between air bubble and hydrophilic mica surfaces (water contact angle, θw < 5°) whereas bubble attachment occurred on hydrophobized mica surfaces. A theoretical model, based on the Reynolds lubrication theory and the augmented Young–Laplace equation including the effects of disjoining pressure, provided excellent agreement with experiment results, indicating the essential physics involved in the Interaction between air bubble and solid surfaces can be elucidated. A hydrophobic Interaction Free Energy per unit area of the form: WH(h) = −γ(1 – cos θw)exp(−h/DH) can be used to quantify the attraction between bubble an...
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a simple algorithm for calculating electrical double layer Interactions in asymmetric electrolytes poisson boltzmann theory
Joint International Conference on Information Sciences, 2002Co-Authors: Derek Y. C. ChanAbstract:Abstract A simple, general, and numerically robust algorithm is presented for calculating the disjoining pressure and Interaction Free Energy per unit area between two identically charged flat plates due to electrical double layer Interactions according to the nonlinear Poisson–Boltzmann theory. The result is applicable to electrolytes with any number of ionic species having any combination of valencies as well as to constant potential, constant charge, or charge regulation boundary conditions on the plates. The algorithm is very simple to implement on commonly available numerical software environments and is therefore particularly suitable for use in data analysis.
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calculations of electric double layer force and Interaction Free Energy between dissimilar surfaces
Joint International Conference on Information Sciences, 1995Co-Authors: Drew Mccormack, Steven L Carnie, Derek Y. C. ChanAbstract:Abstract The nonlinear Poisson-Boltzmann theory is used to calculate the electrical double-layer force and Interaction Free Energy between dissimilarly charged surfaces. For symmetric electrolytes, in addition to cases in which both surfaces maintain constant surface potential or constant surface charge during Interaction, we also consider cases in which one surface maintains constant surface potential and the other maintains constant surface charge. We further present a general algorithm for calculating the double layer force and Interaction Free Energy between surfaces with ionizable surface groups across electrolytes of any valence or composition. These results suggest interesting features of the double-layer Interaction that can be observed by direct force measurement techniques.
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Interaction Free Energy between identical spherical colloidal particles the linearized poisson boltzmann theory
Journal of Colloid and Interface Science, 1993Co-Authors: Steven L Carnie, Derek Y. C. ChanAbstract:Abstract The linearized Poisson-Boltzmann theory is used to calculate the electrical double-layer Interaction Free Energy between identical spherical colloidal particles. Results are given for Interaction under conditions of constant surface potential, constant surface charge, and for the case in which charge regulation due to the dissociation of surface groups may be modeled by a linear relationship between the surface charge and the surface potential. Accurate results are obtained using a two-center expansion for the solution of the linearized Poisson-Boltzmann equation and numerical implementations of the algorithm are given for a full range of particles sizes, κa, and particle separations, κh.
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Interaction Free Energy between Plates with Charge Regulation: A Linearized Model
Journal of Colloid and Interface Science, 1993Co-Authors: Steven L Carnie, Derek Y. C. ChanAbstract:Abstract The linearized Poisson-Boltzmann theory is used to calculate the electrical double layer Interaction Free Energy between two parallel charged plates for the case in which charge regulation due to the dissociation of surface groups may be modelled by the linearized regulation model that specifies a linear relationship between the surface charge and the surface potential. This charge regulation model is characterized by a constant—termed the regulation capacitance of the surface. Analytic expressions for the force per unit area, the Interaction Free Energy per unit area as well as the Interaction Free Energy between two nonidentical spheres in the Deryaguin limit are given for the general case of nonidentical surfaces. An expression for the Interaction Free Energy, applicable to any geometry, is obtained by thermodynamic arguments. Numerical comparisons for the case of identical amphoteric surfaces show that linearizing the charge regulation boundary conditions produces little error in the resultant Interaction Free Energy.
Steven L Carnie - One of the best experts on this subject based on the ideXlab platform.
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calculations of electric double layer force and Interaction Free Energy between dissimilar surfaces
Joint International Conference on Information Sciences, 1995Co-Authors: Drew Mccormack, Steven L Carnie, Derek Y. C. ChanAbstract:Abstract The nonlinear Poisson-Boltzmann theory is used to calculate the electrical double-layer force and Interaction Free Energy between dissimilarly charged surfaces. For symmetric electrolytes, in addition to cases in which both surfaces maintain constant surface potential or constant surface charge during Interaction, we also consider cases in which one surface maintains constant surface potential and the other maintains constant surface charge. We further present a general algorithm for calculating the double layer force and Interaction Free Energy between surfaces with ionizable surface groups across electrolytes of any valence or composition. These results suggest interesting features of the double-layer Interaction that can be observed by direct force measurement techniques.
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Interaction Free Energy between identical spherical colloidal particles the linearized poisson boltzmann theory
Journal of Colloid and Interface Science, 1993Co-Authors: Steven L Carnie, Derek Y. C. ChanAbstract:Abstract The linearized Poisson-Boltzmann theory is used to calculate the electrical double-layer Interaction Free Energy between identical spherical colloidal particles. Results are given for Interaction under conditions of constant surface potential, constant surface charge, and for the case in which charge regulation due to the dissociation of surface groups may be modeled by a linear relationship between the surface charge and the surface potential. Accurate results are obtained using a two-center expansion for the solution of the linearized Poisson-Boltzmann equation and numerical implementations of the algorithm are given for a full range of particles sizes, κa, and particle separations, κh.
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Interaction Free Energy between Plates with Charge Regulation: A Linearized Model
Journal of Colloid and Interface Science, 1993Co-Authors: Steven L Carnie, Derek Y. C. ChanAbstract:Abstract The linearized Poisson-Boltzmann theory is used to calculate the electrical double layer Interaction Free Energy between two parallel charged plates for the case in which charge regulation due to the dissociation of surface groups may be modelled by the linearized regulation model that specifies a linear relationship between the surface charge and the surface potential. This charge regulation model is characterized by a constant—termed the regulation capacitance of the surface. Analytic expressions for the force per unit area, the Interaction Free Energy per unit area as well as the Interaction Free Energy between two nonidentical spheres in the Deryaguin limit are given for the general case of nonidentical surfaces. An expression for the Interaction Free Energy, applicable to any geometry, is obtained by thermodynamic arguments. Numerical comparisons for the case of identical amphoteric surfaces show that linearizing the charge regulation boundary conditions produces little error in the resultant Interaction Free Energy.
Markus Deserno - One of the best experts on this subject based on the ideXlab platform.
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the effective field theory approach towards membrane mediated Interactions between particles
Advances in Colloid and Interface Science, 2014Co-Authors: Cem Yolcu, Robert C Haussman, Markus DesernoAbstract:Abstract Fluid lipid membranes can mediate forces between particles bound to them: A local deformation of the surface geometry created by some object spreads to distant regions, where other objects can respond to it. The physical characteristics of these geometric Interactions, and how they are affected by thermal fluctuations, are well described by the simple continuum curvature-elastic Hamiltonian proposed 40 years ago by Wolfgang Helfrich. Unfortunately, while the underlying principles are conceptually straightforward, the corresponding calculations are not—largely because one must enforce boundary conditions for finite-sized objects. This challenge has inspired several heuristic approaches for expressing the problem in a point particle language. While streamlining the calculations of leading order results and enabling predictions for higher order corrections, the ad hoc nature of the reformulation leaves its domain of validity unclear. In contrast, the framework of Effective Field Theory (EFT) provides a systematic way to construct a completely equivalent point particle description. In this review we present a detailed account for how this is accomplished. In particular, we use a familiar example from electrostatics as an analogy to motivate the key steps needed to construct an EFT, most notably capturing finite size information in point-like “polarizabilities,” and determining their value through a suitable “matching procedure.” The Interaction (Free) Energy then emerges as a systematic cumulant expansion, for which powerful diagrammatic techniques exist, which we also briefly revisit. We then apply this formalism to derive series expansions for Interactions between flat and curved particle pairs, multibody Interactions, as well as corrections to all these Interactions due to thermal fluctuations.
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membrane mediated Interactions between rigid inclusions an effective field theory
Physical Review E, 2012Co-Authors: Cem Yolcu, Markus DesernoAbstract:: An approach based on effective field theory (EFT) is discussed and applied to the problem of surface-mediated Interactions between rigid inclusions of circular footprint on a membrane. Instead of explicitly constraining the surface fluctuations in accord with the boundary conditions around the inclusions, the EFT formalism rewrites the theory; the Hamiltonian of a Freely fluctuating surface is augmented by pointwise localized terms that capture the same constraints. This allows one to compute the Interaction Free Energy as an asymptotic expansion in inverse separations in a systematic, efficient, and transparent way. Both entropic (fluctuation-induced, Casimir-like) and curvature-elastic (ground-state) forces are considered. Our findings include higher-order corrections to known asymptotic results, on both the pair and the multibody levels. We also show that the few previous attempts in the literature at predicting subleading orders missed some terms due to an uncontrolled point-particle approximation.
Yoshiko Maeda - One of the best experts on this subject based on the ideXlab platform.
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numerical studies on electrostatic Interaction forces and the Free Energy between parallel colloidal rods of finite size in skewed configurations
Langmuir, 2021Co-Authors: Hideatsu Maeda, Yoshiko MaedaAbstract:Formulas for Interaction forces F(s) and the Free Energy G(s) between two parallel charged prismatic rods of various scaled values of d, ψs, and L in skewed configurations are obtained, where s is the lengthwise positional difference between the front-end faces of the respective rods, and d is the minimal distance between the opposing faces of the rods, ψs is the electric surface potential, L is the length of the rods. To obtain the Free-Energy function G(s), (i) 3D spatial distributions of the electric potential ψ around two rods were determined by numerically solving the nonlinear Poisson-Boltzmann equation with a finite element method, (ii) with the ψ distributions so determined, the lengthwise Interaction electrostatic Maxwell stress tangential to the midplane between the rods was calculated to obtain the (discrete) s dependence of the stress, and (iii) by introducing two different fitting functions, the discrete s dependence was transformed into a continuous force function, F(s), which was then lengthwise integrated to derive G(s). It was found that the curves of G(s) linearly decreased with increasing s between 1 and L + 1 due to a localization of the stress. Although natural, it is of interest that the values of G(0) calculated for rods of various values of d, ψs, and L were in good agreement with those of the Interaction Free Energy obtained in our preceding work by the widthwise integration of repulsive electrostatic forces normal to the midplane between the parallel rods in nonskewed configurations.
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numerical studies on electrical Interaction forces and Free Energy between colloidal plates of finite size
Langmuir, 2020Co-Authors: Hideatsu Maeda, Yoshiko MaedaAbstract:By solving the nonlinear Poisson-Boltzmann (PB) equation with a finite element method (FEM), three-dimensional (3D) spatial distributions of the electric potential (ψ, scaled) in electrolyte solutions having two charged parallel finite plates (including cubes and prismatic rods) are determined for various separations (d, scaled by the Debye length, κ-1), surface potentials (ψs), and plate dimensions (length × width × thickness, each scaled by κ-1). The total Interaction force between two plates, F, is the sum of the electrostatic double-layer (EDL) repulsion (the osmotic pressure, Fosm) and the Maxwell electrostatic stress (Fes). The EDL repulsion is estimated using the distribution of ψ not only between the facing surfaces of two parallel plates but also around the other extremities of the plates. The Maxwell stress (Fes) is localized near the extremities to act as a repulsive force on the midplane between the two plates. The ratio Fes/F is 0.07-0.5, depending on d, ψs, and dimensions. It is found that, with increasing dimensions, the total F values per unit area calculated for finite plates, F, decreasingly approach the exact ones for parallel infinite plates, Finf; for example, at d = 1 and ψs = 5, the ratio F/Finf is 2.83 for plates with dimensions of 1 × 1 × 1 and 1.18 for plates of 10 × 10 × 1. The repulsions arising from the extremities cannot be neglected for plates with dimensions <10 × 10 × 1. Furthermore, the total Interaction forces (F) are calculated at a series of discrete d values, respectively, for parallel plates. We introduce a force fitting function, Ff(d), with parameters that can be determined so that Ff(d) fits well to the calculated serial F values. By integrating the Ff(d), we obtain the Interaction Free Energy, G(d), for finite parallel plates that consists of two Γ functions.
Cem Yolcu - One of the best experts on this subject based on the ideXlab platform.
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the effective field theory approach towards membrane mediated Interactions between particles
Advances in Colloid and Interface Science, 2014Co-Authors: Cem Yolcu, Robert C Haussman, Markus DesernoAbstract:Abstract Fluid lipid membranes can mediate forces between particles bound to them: A local deformation of the surface geometry created by some object spreads to distant regions, where other objects can respond to it. The physical characteristics of these geometric Interactions, and how they are affected by thermal fluctuations, are well described by the simple continuum curvature-elastic Hamiltonian proposed 40 years ago by Wolfgang Helfrich. Unfortunately, while the underlying principles are conceptually straightforward, the corresponding calculations are not—largely because one must enforce boundary conditions for finite-sized objects. This challenge has inspired several heuristic approaches for expressing the problem in a point particle language. While streamlining the calculations of leading order results and enabling predictions for higher order corrections, the ad hoc nature of the reformulation leaves its domain of validity unclear. In contrast, the framework of Effective Field Theory (EFT) provides a systematic way to construct a completely equivalent point particle description. In this review we present a detailed account for how this is accomplished. In particular, we use a familiar example from electrostatics as an analogy to motivate the key steps needed to construct an EFT, most notably capturing finite size information in point-like “polarizabilities,” and determining their value through a suitable “matching procedure.” The Interaction (Free) Energy then emerges as a systematic cumulant expansion, for which powerful diagrammatic techniques exist, which we also briefly revisit. We then apply this formalism to derive series expansions for Interactions between flat and curved particle pairs, multibody Interactions, as well as corrections to all these Interactions due to thermal fluctuations.
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membrane mediated Interactions between rigid inclusions an effective field theory
Physical Review E, 2012Co-Authors: Cem Yolcu, Markus DesernoAbstract:: An approach based on effective field theory (EFT) is discussed and applied to the problem of surface-mediated Interactions between rigid inclusions of circular footprint on a membrane. Instead of explicitly constraining the surface fluctuations in accord with the boundary conditions around the inclusions, the EFT formalism rewrites the theory; the Hamiltonian of a Freely fluctuating surface is augmented by pointwise localized terms that capture the same constraints. This allows one to compute the Interaction Free Energy as an asymptotic expansion in inverse separations in a systematic, efficient, and transparent way. Both entropic (fluctuation-induced, Casimir-like) and curvature-elastic (ground-state) forces are considered. Our findings include higher-order corrections to known asymptotic results, on both the pair and the multibody levels. We also show that the few previous attempts in the literature at predicting subleading orders missed some terms due to an uncontrolled point-particle approximation.