Journal of physics. Condensed matter : an Institute of Physics journal, Jan 15, 2017
When immiscible liquids are subject to electric fields interfacial forces arise due to a differen... more When immiscible liquids are subject to electric fields interfacial forces arise due to a difference in the permittivity or the conductance of the liquids, and these forces lead to shape change in droplets or to interfacial instabilities. In this topical review we discuss recent advances in the theory and experiments of liquids in electric fields with an emphasis on liquids which are initially miscible and demix under the influence of an external field. In purely dielectric liquids demixing occurs if the electrode geometry leads to sufficiently large field gradients. In polar liquids field gradients are prevalent due to screening by dissociated ions irrespective of the electrode geometry. We examine the conditions for these 'electro prewetting' transitions and highlight few possible systems where they might be important, such as in stabilization of colloids and in gating of pores in membranes.
Abstract We present here the recent developments in the studies of self-organization in abiotic, ... more Abstract We present here the recent developments in the studies of self-organization in abiotic, biotic (bacterial) colonies and man-made (programmable chips) systems, aimed at seeking to unravel the general principles of biotic self-organization. A typical bacterial colony ...
A simple, quantitative model is suggested to explain the specificity of ions with respect to inhi... more A simple, quantitative model is suggested to explain the specificity of ions with respect to inhibition of bubble coalescence following a dynamic approach. For the first time, the mode of thinning of the film in between the bubbles, as determined by the density of the bubble dispersion, is recognized as a determining factor. The specificity of the ionic effect is explained by a major difference in adsorption properties of ions, which is enhanced by the film thinning. This leads to charge separation that forms an electrical double layer at each interface of the thin, liquid film, and consequently to electrostatic repulsion. This effect is described by a simple theoretical model that consists of two fundamental equations: mass conservation of each ion in the film, and the Gibbs adsorption equation. In addition, we explain the rapid coalescence of bubbles in purified water under dynamic conditions, which is in contrast with the very slow coalescence under quasi-static conditions.
Abstract We present here the recent developments in the studies of self-organization in abiotic, ... more Abstract We present here the recent developments in the studies of self-organization in abiotic, biotic (bacterial) colonies and man-made (programmable chips) systems, aimed at seeking to unravel the general principles of biotic self-organization. A typical bacterial colony ...
There is much renewed interest in the arrangement and kinetic of hydrogen bonds in water and heav... more There is much renewed interest in the arrangement and kinetic of hydrogen bonds in water and heavy water. D(2)O forms a higher average number of hydrogen bonds per molecule (10% more) compared to the case for H(2)O, which cause a larger entropic cost for solvating molecules in D(2)O. Here we used isothermal titration calorimetry (ITC) to investigate the enthalpy of titration of D(2)O-H(2)O solutions with different D/H isotope ratios. We found significant enthalpy deviations (exothermic contributions) relative to the computed enthalpy for the limit of ideal mixing both for dilution titration and for concentration titration (injection of solutions with lower D/H ratios into solutions with higher ratios and vice versa). We propose that the observed exothermic deviations might be connected to entropic effects associated with differences in the H and D arrangements that depend on the D/H ratio of the solutions. This ratio varies during the titration processes, leading to the entropy production beyond that of ideal mixing. We also used the ITC in the nonstirring mode to measure the titration kinetics and found long relaxation times of up to tens of minutes for the concentration titrations (but not for the dilution titrations). These observations are consistent with slow propagation of the reaction H(2)O + D(2)O <--> 2HDO that involves hopping of deuterium and rearrangements of the H and D bonding.
Journal of physics. Condensed matter : an Institute of Physics journal, Jan 15, 2017
When immiscible liquids are subject to electric fields interfacial forces arise due to a differen... more When immiscible liquids are subject to electric fields interfacial forces arise due to a difference in the permittivity or the conductance of the liquids, and these forces lead to shape change in droplets or to interfacial instabilities. In this topical review we discuss recent advances in the theory and experiments of liquids in electric fields with an emphasis on liquids which are initially miscible and demix under the influence of an external field. In purely dielectric liquids demixing occurs if the electrode geometry leads to sufficiently large field gradients. In polar liquids field gradients are prevalent due to screening by dissociated ions irrespective of the electrode geometry. We examine the conditions for these 'electro prewetting' transitions and highlight few possible systems where they might be important, such as in stabilization of colloids and in gating of pores in membranes.
Abstract We present here the recent developments in the studies of self-organization in abiotic, ... more Abstract We present here the recent developments in the studies of self-organization in abiotic, biotic (bacterial) colonies and man-made (programmable chips) systems, aimed at seeking to unravel the general principles of biotic self-organization. A typical bacterial colony ...
A simple, quantitative model is suggested to explain the specificity of ions with respect to inhi... more A simple, quantitative model is suggested to explain the specificity of ions with respect to inhibition of bubble coalescence following a dynamic approach. For the first time, the mode of thinning of the film in between the bubbles, as determined by the density of the bubble dispersion, is recognized as a determining factor. The specificity of the ionic effect is explained by a major difference in adsorption properties of ions, which is enhanced by the film thinning. This leads to charge separation that forms an electrical double layer at each interface of the thin, liquid film, and consequently to electrostatic repulsion. This effect is described by a simple theoretical model that consists of two fundamental equations: mass conservation of each ion in the film, and the Gibbs adsorption equation. In addition, we explain the rapid coalescence of bubbles in purified water under dynamic conditions, which is in contrast with the very slow coalescence under quasi-static conditions.
Abstract We present here the recent developments in the studies of self-organization in abiotic, ... more Abstract We present here the recent developments in the studies of self-organization in abiotic, biotic (bacterial) colonies and man-made (programmable chips) systems, aimed at seeking to unravel the general principles of biotic self-organization. A typical bacterial colony ...
There is much renewed interest in the arrangement and kinetic of hydrogen bonds in water and heav... more There is much renewed interest in the arrangement and kinetic of hydrogen bonds in water and heavy water. D(2)O forms a higher average number of hydrogen bonds per molecule (10% more) compared to the case for H(2)O, which cause a larger entropic cost for solvating molecules in D(2)O. Here we used isothermal titration calorimetry (ITC) to investigate the enthalpy of titration of D(2)O-H(2)O solutions with different D/H isotope ratios. We found significant enthalpy deviations (exothermic contributions) relative to the computed enthalpy for the limit of ideal mixing both for dilution titration and for concentration titration (injection of solutions with lower D/H ratios into solutions with higher ratios and vice versa). We propose that the observed exothermic deviations might be connected to entropic effects associated with differences in the H and D arrangements that depend on the D/H ratio of the solutions. This ratio varies during the titration processes, leading to the entropy production beyond that of ideal mixing. We also used the ITC in the nonstirring mode to measure the titration kinetics and found long relaxation times of up to tens of minutes for the concentration titrations (but not for the dilution titrations). These observations are consistent with slow propagation of the reaction H(2)O + D(2)O <--> 2HDO that involves hopping of deuterium and rearrangements of the H and D bonding.
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Papers by Yael Katsir