Y. de Decker - Academia.edu (original) (raw)

Papers by Y. de Decker

Appendix A: Microscopic derivation of the Langmuir kinetics

We derive general conditions for the emergence of sustained chemomechanical oscillations from a n... more We derive general conditions for the emergence of sustained chemomechanical oscillations from a non-oscillatory adsorption/desorption reaction in a gas/solid porous medium. The oscillations arise from the nonlinear response of the solid matrix to the loading of the adsorbed species. More particularly, we prove that in order for oscillations to occur, adsorption of the gas must in general cause a swelling of the solid matrix. We also investigate the prototypical case of Langmuir kinetics both numerically and analytically.This article is part of the theme issue 'Dissipative structures in matter out of equilibrium: from chemistry, photonics and biology (part 2)'.

Water produced in a polymer electrolyte membrane (PEM) fuel cell enhances membrane proton conduct... more Water produced in a polymer electrolyte membrane (PEM) fuel cell enhances membrane proton conductivity; this positive feedback loop can lead to current ignition. Gas-phase convection and membrane diffusion of water coupled with water production in a simplified two-dimensional PEM fuel cell leads to localized ignition and current density front propagation in the cell. Co-current gas flow in the anode and cathode channels causes ignition at the cell outlet, and membrane diffusion causes the front to slowly propagate toward the inlet; counter-current flow in the anode and cathode channels causes ignition in the interior of the cell, with the current density fronts subsequently spreading toward both inlets. The basic chemistry and physics of the spatiotemporal nonlinear dynamics of the two-dimensional fuel cell current can be captured by extending a simple one-dimensional stirred tank reactor model to a “tanks-in-series ” model.

In this essay we comment on our recent paper "Pigment cell movement is not required for gene... more In this essay we comment on our recent paper "Pigment cell movement is not required for generation of Turing patterns in zebrafish skin" When Catarina Vicente (Community Manager of The Node) proposed us to write a post about our recent paper on pattern formation in zebrafish [1] we were very glad for the opportunity she was giving us to tell the background story about our work in this blog. We are not biologists (we are two theoretical chemists working in the field of nonlinear chemistry and self-organization) and our experience in developmental biology before undertaking this research essentially consisted in having read some books and papers about biochemical self-organization, in having discussions with colleagues, and in attending a few seminars. We think we have somewhat "improved" since then, but we must admit that we still feel like neophytes in the community of developmental biologists. This was the main reason why we were so happy about Dr. Vicente'...

Water produced in a polymer electrolyte membrane (PEM) fuel cell enhances membrane proton conduct... more Water produced in a polymer electrolyte membrane (PEM) fuel cell enhances membrane proton conductivity; this positive feedback loop can lead to current ignition. Gas-phase convection and membrane diffusion of water coupled with water production in a simplified two-dimensional PEM fuel cell leads to localized ignition and current density front propagation in the cell. Co-current gas flow in the anode and cathode channels causes ignition at the cell outlet, and membrane diffusion causes the front to slowly propagate toward the inlet; counter-current flow in the anode and cathode channels causes ignition in the interior of the cell, with the current density fronts subsequently spreading toward both inlets. The basic chemistry and physics of the spatiotemporal nonlinear dynamics of the two-dimensional fuel cell current can be captured by extending a simple one-dimensional stirred tank reactor model to a “tanks-in-series ” model.

8 ABSTRACT: When two miscible solutions, each containing a reactive species, 9 are put in contact... more 8 ABSTRACT: When two miscible solutions, each containing a reactive species, 9 are put in contact in the gravity field, local variations in the density due to the 10 reaction can induce convective motion and mixing. We characterize here both 11 experimentally and theoretically such buoyancy-driven instabilities induced by 12 the neutralization of a strong acid by a strong base in aqueous solutions. The 13 diversepatternsobtainedareshowntodependonthetypeofreactants usedand 14 on their relative concentrations. They have their origin in a combination of 15 classical hydrodynamic instabilities including differential diffusion of the solutes 16 involved while temperature effects only play a marginal role.

Reactive systems are known to give birth to complex spatiotemporal phenomena, when they are maint... more Reactive systems are known to give birth to complex spatiotemporal phenomena, when they are maintained far enough from their equilibrium state. There are literally hundreds of experimental evidences showing the emergence of such self-organized behaviors at the macroscopic scale. Examples include the appearance of regular oscillations of concentration in both space and time, the formation of stationary spatial organization of reactants and products, and the emergence of spatiotemporal chaos, to cite but a few examples. The theoretical understanding of these phenomena can be considered as being well established. Chemical reactions play a central role in the appearance of complex behaviors because they are nonlinear processes. Indeed, the rates of reactions are typically polynomials of the concentrations and moreover include constants that depend exponentially on the temperature. Because of this, the equations ruling the spatiotemporal development of chemical reactions, which often tak...

Encyclopedia of Interfacial Chemistry

Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences

We derive general conditions for the emergence of sustained chemomechanical oscillations from a n... more We derive general conditions for the emergence of sustained chemomechanical oscillations from a non-oscillatory adsorption/desorption reaction in a gas/solid porous medium. The oscillations arise from the nonlinear response of the solid matrix to the loading of the adsorbed species. More particularly, we prove that, in order for oscillations to occur, adsorption of the gas must in general cause a swelling of the solid matrix. We also investigate the prototypical case of Langmuir kinetics both numerically and analytically. This article is part of the theme issue ‘Dissipative structures in matter out of equilibrium: from chemistry, photonics and biology (part 2)’.

The European Physical Journal Special Topics, 2015

A new approach to stochastic thermodynamics is developed, in which the local equilibrium hypothes... more A new approach to stochastic thermodynamics is developed, in which the local equilibrium hypothesis is extended to incorporate the effect of fluctuations. A fluctuating entropy in the form of a random functional of the fluctuating state variables is introduced, whose balance equation allows to identify the stochastic entropy flux and stochastic entropy production. The statistical properties of these quantities are analyzed and illustrated on representative examples.

Springer Series in Materials Science, 2015

Reactive systems are known to give birth to complex spatiotemporal phenomena, when they are maint... more Reactive systems are known to give birth to complex spatiotemporal phenomena, when they are maintained far enough from their equilibrium state.

Journal of Statistical Physics, 2015

Classical chemical thermodynamics predicts that the equilibrium composition of a reactive system ... more Classical chemical thermodynamics predicts that the equilibrium composition of a reactive system is entirely defined by the equilibrium constants of the different reactions involved. In this paper we show that for nonlinear reactions taking place on a low-dimensional support this is not true anymore: the equilibrium state depends on the mechanistic details of the chemical processes, so that even two reactions having the same mean field kinetics and equilibrium constants can reach a different equilibrium composition, depending on the microscopic mechanism. We illustrate this point by simulations and mathematical analyses of a simple autocatalytic scheme, and we propose a theoretical route to discriminate between the different cases.

The dynamics of NO2 reduction over Pt metal is studied by means of real-time Field Emission Micro... more The dynamics of NO2 reduction over Pt metal is studied by means of real-time Field Emission Microscopy (FEM). The extremity of a nanosized Pt tip acts as a catalyst grain. FEM provides nanoscale lateral resolution. Dynamic imaging is based on monitoring local brightness changes due to adsorbate-induced variations of the local work function. Several non-linear behaviors of varying complexity are observed, from hysteresis to periodic oscillations. A mechanism for the observed kinetic oscillations is finally proposed.

Mesoscopic Modeling of Chemical Surface ReactionsReactions such as those encountered in heterogen... more Mesoscopic Modeling of Chemical Surface ReactionsReactions such as those encountered in heterogeneous catalysis form a specific class of non-equilibrium, nonlinear systems: they take place on low-dimensional supports, the surfaces, exhibiting a particularly restricted geometry. Because of this geometrical restriction, fluctuation-induced nanometric self-organization can spontaneously arise and can lead to a compartmentalization of the reactants and the products. We use mesoscopic stochastic simulations and theoretical approaches to model the dynamics at these scales and to understand the connection between the microscopic details of the processes and the macroscopic rate laws for concentrations. In particular, we study the propagation of waves, the emergence of coherent oscillatory and explosive behaviors and apply these techniques for the modeling of experimental systems such as the H2+O2/Rh reaction with co-adsorbed potassium or the NO+H2 reaction on platinum.

The Journal of Physical Chemistry B, 2011

When two miscible solutions, each containing a reactive species, are put in contact in the gravit... more When two miscible solutions, each containing a reactive species, are put in contact in the gravity field, local variations in the density due to the reaction can induce convective motion and mixing. We characterize here both experimentally and theoretically such buoyancy-driven instabilities induced by the neutralization of a strong acid by a strong base in aqueous solutions. The diverse patterns obtained are shown to depend on the type of reactants used and on their relative concentrations. They have their origin in a combination of classical hydrodynamic instabilities including differential diffusion of the solutes involved while temperature effects only play a marginal role.

Appendix A: Microscopic derivation of the Langmuir kinetics

We derive general conditions for the emergence of sustained chemomechanical oscillations from a n... more We derive general conditions for the emergence of sustained chemomechanical oscillations from a non-oscillatory adsorption/desorption reaction in a gas/solid porous medium. The oscillations arise from the nonlinear response of the solid matrix to the loading of the adsorbed species. More particularly, we prove that in order for oscillations to occur, adsorption of the gas must in general cause a swelling of the solid matrix. We also investigate the prototypical case of Langmuir kinetics both numerically and analytically.This article is part of the theme issue 'Dissipative structures in matter out of equilibrium: from chemistry, photonics and biology (part 2)'.

Water produced in a polymer electrolyte membrane (PEM) fuel cell enhances membrane proton conduct... more Water produced in a polymer electrolyte membrane (PEM) fuel cell enhances membrane proton conductivity; this positive feedback loop can lead to current ignition. Gas-phase convection and membrane diffusion of water coupled with water production in a simplified two-dimensional PEM fuel cell leads to localized ignition and current density front propagation in the cell. Co-current gas flow in the anode and cathode channels causes ignition at the cell outlet, and membrane diffusion causes the front to slowly propagate toward the inlet; counter-current flow in the anode and cathode channels causes ignition in the interior of the cell, with the current density fronts subsequently spreading toward both inlets. The basic chemistry and physics of the spatiotemporal nonlinear dynamics of the two-dimensional fuel cell current can be captured by extending a simple one-dimensional stirred tank reactor model to a “tanks-in-series ” model.

In this essay we comment on our recent paper "Pigment cell movement is not required for gene... more In this essay we comment on our recent paper "Pigment cell movement is not required for generation of Turing patterns in zebrafish skin" When Catarina Vicente (Community Manager of The Node) proposed us to write a post about our recent paper on pattern formation in zebrafish [1] we were very glad for the opportunity she was giving us to tell the background story about our work in this blog. We are not biologists (we are two theoretical chemists working in the field of nonlinear chemistry and self-organization) and our experience in developmental biology before undertaking this research essentially consisted in having read some books and papers about biochemical self-organization, in having discussions with colleagues, and in attending a few seminars. We think we have somewhat "improved" since then, but we must admit that we still feel like neophytes in the community of developmental biologists. This was the main reason why we were so happy about Dr. Vicente'...

Water produced in a polymer electrolyte membrane (PEM) fuel cell enhances membrane proton conduct... more Water produced in a polymer electrolyte membrane (PEM) fuel cell enhances membrane proton conductivity; this positive feedback loop can lead to current ignition. Gas-phase convection and membrane diffusion of water coupled with water production in a simplified two-dimensional PEM fuel cell leads to localized ignition and current density front propagation in the cell. Co-current gas flow in the anode and cathode channels causes ignition at the cell outlet, and membrane diffusion causes the front to slowly propagate toward the inlet; counter-current flow in the anode and cathode channels causes ignition in the interior of the cell, with the current density fronts subsequently spreading toward both inlets. The basic chemistry and physics of the spatiotemporal nonlinear dynamics of the two-dimensional fuel cell current can be captured by extending a simple one-dimensional stirred tank reactor model to a “tanks-in-series ” model.

8 ABSTRACT: When two miscible solutions, each containing a reactive species, 9 are put in contact... more 8 ABSTRACT: When two miscible solutions, each containing a reactive species, 9 are put in contact in the gravity field, local variations in the density due to the 10 reaction can induce convective motion and mixing. We characterize here both 11 experimentally and theoretically such buoyancy-driven instabilities induced by 12 the neutralization of a strong acid by a strong base in aqueous solutions. The 13 diversepatternsobtainedareshowntodependonthetypeofreactants usedand 14 on their relative concentrations. They have their origin in a combination of 15 classical hydrodynamic instabilities including differential diffusion of the solutes 16 involved while temperature effects only play a marginal role.

Reactive systems are known to give birth to complex spatiotemporal phenomena, when they are maint... more Reactive systems are known to give birth to complex spatiotemporal phenomena, when they are maintained far enough from their equilibrium state. There are literally hundreds of experimental evidences showing the emergence of such self-organized behaviors at the macroscopic scale. Examples include the appearance of regular oscillations of concentration in both space and time, the formation of stationary spatial organization of reactants and products, and the emergence of spatiotemporal chaos, to cite but a few examples. The theoretical understanding of these phenomena can be considered as being well established. Chemical reactions play a central role in the appearance of complex behaviors because they are nonlinear processes. Indeed, the rates of reactions are typically polynomials of the concentrations and moreover include constants that depend exponentially on the temperature. Because of this, the equations ruling the spatiotemporal development of chemical reactions, which often tak...

Encyclopedia of Interfacial Chemistry

Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences

We derive general conditions for the emergence of sustained chemomechanical oscillations from a n... more We derive general conditions for the emergence of sustained chemomechanical oscillations from a non-oscillatory adsorption/desorption reaction in a gas/solid porous medium. The oscillations arise from the nonlinear response of the solid matrix to the loading of the adsorbed species. More particularly, we prove that, in order for oscillations to occur, adsorption of the gas must in general cause a swelling of the solid matrix. We also investigate the prototypical case of Langmuir kinetics both numerically and analytically. This article is part of the theme issue ‘Dissipative structures in matter out of equilibrium: from chemistry, photonics and biology (part 2)’.

The European Physical Journal Special Topics, 2015

A new approach to stochastic thermodynamics is developed, in which the local equilibrium hypothes... more A new approach to stochastic thermodynamics is developed, in which the local equilibrium hypothesis is extended to incorporate the effect of fluctuations. A fluctuating entropy in the form of a random functional of the fluctuating state variables is introduced, whose balance equation allows to identify the stochastic entropy flux and stochastic entropy production. The statistical properties of these quantities are analyzed and illustrated on representative examples.

Springer Series in Materials Science, 2015

Reactive systems are known to give birth to complex spatiotemporal phenomena, when they are maint... more Reactive systems are known to give birth to complex spatiotemporal phenomena, when they are maintained far enough from their equilibrium state.

Journal of Statistical Physics, 2015

Classical chemical thermodynamics predicts that the equilibrium composition of a reactive system ... more Classical chemical thermodynamics predicts that the equilibrium composition of a reactive system is entirely defined by the equilibrium constants of the different reactions involved. In this paper we show that for nonlinear reactions taking place on a low-dimensional support this is not true anymore: the equilibrium state depends on the mechanistic details of the chemical processes, so that even two reactions having the same mean field kinetics and equilibrium constants can reach a different equilibrium composition, depending on the microscopic mechanism. We illustrate this point by simulations and mathematical analyses of a simple autocatalytic scheme, and we propose a theoretical route to discriminate between the different cases.

The dynamics of NO2 reduction over Pt metal is studied by means of real-time Field Emission Micro... more The dynamics of NO2 reduction over Pt metal is studied by means of real-time Field Emission Microscopy (FEM). The extremity of a nanosized Pt tip acts as a catalyst grain. FEM provides nanoscale lateral resolution. Dynamic imaging is based on monitoring local brightness changes due to adsorbate-induced variations of the local work function. Several non-linear behaviors of varying complexity are observed, from hysteresis to periodic oscillations. A mechanism for the observed kinetic oscillations is finally proposed.

Mesoscopic Modeling of Chemical Surface ReactionsReactions such as those encountered in heterogen... more Mesoscopic Modeling of Chemical Surface ReactionsReactions such as those encountered in heterogeneous catalysis form a specific class of non-equilibrium, nonlinear systems: they take place on low-dimensional supports, the surfaces, exhibiting a particularly restricted geometry. Because of this geometrical restriction, fluctuation-induced nanometric self-organization can spontaneously arise and can lead to a compartmentalization of the reactants and the products. We use mesoscopic stochastic simulations and theoretical approaches to model the dynamics at these scales and to understand the connection between the microscopic details of the processes and the macroscopic rate laws for concentrations. In particular, we study the propagation of waves, the emergence of coherent oscillatory and explosive behaviors and apply these techniques for the modeling of experimental systems such as the H2+O2/Rh reaction with co-adsorbed potassium or the NO+H2 reaction on platinum.

The Journal of Physical Chemistry B, 2011

When two miscible solutions, each containing a reactive species, are put in contact in the gravit... more When two miscible solutions, each containing a reactive species, are put in contact in the gravity field, local variations in the density due to the reaction can induce convective motion and mixing. We characterize here both experimentally and theoretically such buoyancy-driven instabilities induced by the neutralization of a strong acid by a strong base in aqueous solutions. The diverse patterns obtained are shown to depend on the type of reactants used and on their relative concentrations. They have their origin in a combination of classical hydrodynamic instabilities including differential diffusion of the solutes involved while temperature effects only play a marginal role.