Boris Zaltzman - Academia.edu (original) (raw)
Papers by Boris Zaltzman
Current Opinion in Colloid & Interface Science
Scientific Reports, 2021
Osmosis-solution (solvent) flow through non-perfectly (perfectly) semipermeable membranes-is a fu... more Osmosis-solution (solvent) flow through non-perfectly (perfectly) semipermeable membranes-is a fundamental classical phenomenon of major practical importance. One of its potentially useful technological applications is the Pressure Retarded Osmosis (PRO) employed for energy harvesting from salinity variations 1. In this process the flow resulting from the osmotic pressure drop between fresh and saline water is used to drive a turbine. Unfortunately, at the current stage, in spite of its extreme simplicity and conceptual beauty, this process does not appear to be practically viable due to insufficient power efficiency 2. This assessment could be radically changed by the recently theoretically predicted "Breakthrough" operation mode of PRO 3. In this mode, the solute concentration at the interface between the porous support and the dense selective barrier layer of a non-perfect ('leaky') asymmetric membrane employed in PRO decreases with the increase of draw concentration, and, thus, the impeding effect of internal concentration polarization is eliminated, Fig. 1. The existence of this mode was predicted by Yaroshchuk based on the accurate analysis of the system of classical local Spiegler-Kedem-Katchalsky (SKK) equations of membrane transport with three constant coefficients for the barrier layer: solute permeability (diffusivity), solute reflection coefficient and hydraulic permeability 4. In a still more recent study Wu and Field 5 , contested the physical feasibility of "Breakthrough mode" and casted doubt upon the suitability of SKK equations with constant coefficients to PRO. In this note we re-derive the SKK equations based on a very simple capillary friction model of membrane transport in the dense barrier layer and identify the problem with the constant coefficients' assumption resulting in the occurrence of "Breakthrough mode". Our derivation results in recovering the SKK equations in the dilute solution limit, albeit with hydraulic permeability dependent on the local solute concentration in the barrier layer (modified SKK equations, MSKK). Taking into account this dependence, necessary for preserving the detailed force balance in the barrier layer, eliminates the existence of the "Breakthrough mode".
t,hrough ion exchange membranes. latter rule in favor of surface versus hl~c origin of overlimiti... more t,hrough ion exchange membranes. latter rule in favor of surface versus hl~c origin of overlimiting conductance along with those of recent experiments wit,h modified membranes. These linear convection, developing from the respective instability, are reported exchange membrane. Results of numerical calculation pertaining to nonof linear stability analysis of quiescent electrodiffusion.through a flat ion librium electroosmotic slip condition is recapitulated along with the results overlimiting conductance through the membrane. Derivation of nonequitroosmosis at, an ion exchange electrodialysis membrane, as a source of The paper is concerned with convection induced by nonequilibrium elec
Physical Review Fluids, 2017
Equilibrium electroconvective instability at a perfectly charge-selective solid, such as ion-exch... more Equilibrium electroconvective instability at a perfectly charge-selective solid, such as ion-exchange membrane or metal electrode, previously deemed impossible, is possible if one takes into account finite electrical conductivity of the solid. A simple model of electroconvective diffusion of ions in the depleted diffusion layer in this system predicts a supercritical transition to instability in the vicinity of the limiting current, as opposed to the subcritical transition for the previously studied nonequilibrium instability related to the extended space charge. The linear stability analysis in this model yields the division of the parameter space into domains in which each instability mechanism with its characteristic signatures dominates. Identification of the particular instability mechanism for a given system requires a detailed experimental study of the vicinity of the instability threshold in terms of both the voltage versus current dependence and flow visualization.
Physical Review Research, 2020
Hierarchical structure is an essential part of complexity, important notion relevant for a wide r... more Hierarchical structure is an essential part of complexity, important notion relevant for a wide range of applications ranging from biological population dynamics through robotics to social sciences. In this paper we propose a simple cellular-automata tool for study of hierarchical population dynamics.
Physical Review Fluids, 2020
Environmental Engineering Science, 2002
Russian Journal of Electrochemistry, 2017
Encyclopedia of Microfluidics and Nanofluidics, 2015
Physical review. E, Statistical, nonlinear, and soft matter physics, 2010
This paper is concerned with ionic currents from an electrolyte solution into a charge selective ... more This paper is concerned with ionic currents from an electrolyte solution into a charge selective solid, such as an electrode, an ion exchange membrane or an array of nanochannels in a microfluidic system. All systems of this kind have characteristic voltage-current curves with segments in which current nearly saturates at some plateau values due to concentration polarization--formation of solute concentration gradients under the passage of a dc current. A number of seemingly different phenomena occurring in that range, such as anomalous rectification in cathodic copper deposition from a copper sulfate solution, superfast vortexes near an ion-exchange granule, overlimiting conductance in electrodialysis and the recently observed nonequilibrium electro-osmotic instability, result from formation of an additional extended space charge layer next to that of a classical electrical double layer at the solid/liquid interface or, rather, from the peculiar features of the extended space charg...
Encyclopedia of Microfluidics and Nanofluidics, 2013
Physical Review Letters, 2011
We revisit the classical problem of diffusion-limited ion transport to a membrane (or electrode) ... more We revisit the classical problem of diffusion-limited ion transport to a membrane (or electrode) by considering the effects of charged side walls. Using simple mathematical models and numerical simulations, we identify three basic mechanisms for over-limiting current in a microchannel: (i) surface conduction carried by excess counterions, which dominates for very thin channels, (ii) convection by electro-osmotic flow on the side walls, which dominates for thicker channels and transitions to (iii) electro-osmotic instability on the membrane end in very thick channels. These intriguing electrokinetic phenomena may find applications in biological separations, water desalination, and electrochemical energy storage.
Atención Primaria, 2009
A shape phase transition between stable octupole deformation and octupole vibrations in Th nuclei... more A shape phase transition between stable octupole deformation and octupole vibrations in Th nuclei is analyzed in a microscopic framework based on nuclear density functional theory. The relativistic functional DD-PC1 is used to calculate axially-symmetric quadrupole-octupole constrained energy surfaces. Observables related to order parameters are computed using an interacting-boson Hamiltonian, with parameters determined by mapping the microscopic energy surfaces to the expectation value of the Hamiltonian in the boson condensate. The systematics of constrained energy surfaces and low-energy excitation spectra point to the occurrence of a phase transition between octupole-deformed shapes and shapes characterized by octupole-soft potentials.
APS Meeting …, 2010
A simple 1D locally electroneutral (LEN) electro-diffusive model explains steady-state fluidic re... more A simple 1D locally electroneutral (LEN) electro-diffusive model explains steady-state fluidic rectification in terms of asymmetry in the diffusion layers flanking a charge-selective element such as a porous membrane or nano-pore. The selectivity in such systems is a function of ...
Physical Review Fluids
Experimental and numerical results reveal a distinct signature of electroconvective instability i... more Experimental and numerical results reveal a distinct signature of electroconvective instability in the transient response for a microchannel-nanoslot system. We study the development of the electroconvective instability from equilibrium during the transient chronopotentiometric (galvanostatic operation) and chronoamperometric (potentiostatic operation) responses at overlimiting current conditions and observe a distinct signature of nonmonotonic transient response resulting from the emergence of electroconvective instability. This stands in contrast to previously reported experimental nonmonotonic transient responses in heterogeneous membrane systems associated with linear electroosmotic flow.
Quarterly of Applied Mathematics
Inexpensive highly permselective heterogeneous ion exchange membranes are prohibitively polarizab... more Inexpensive highly permselective heterogeneous ion exchange membranes are prohibitively polarizable by a direct electric current for use in electrodialysis. According to recent experiments, polarizability of these membranes may be considerably reduced by casting on their surface a thin layer of cross-linked polyelectrolyte, weakly charged with the same sign as the membrane’s charge. The present paper is concerned with this effect. In order to explain this feature, a simple limiting ion-exchange ’funnel’ model of a modified membrane is derived from the original two-layer model. In this model, asymptotically valid for a thin coating, solution of the ionic transport equations in it is replaced, via a suitable averaging procedure, by a single nonlinear boundary condition for the membrane/solution interface, which itself has the same order as the bulk equation. Rigorous analysis of the ’funnel’ model shows that the value of the limiting current through a modified membrane, which is the m...
Quarterly of Applied Mathematics
The disappearance of the mushy region in a multidimensional one-phase Stefan problem is discussed... more The disappearance of the mushy region in a multidimensional one-phase Stefan problem is discussed. In the case of a piecewise-smooth boundary of the domain and bounded initial-boundary data, sufficient conditions for the disappearance of the mushy zone in a finite time are presented. For a C-smooth boundary and appropriately smooth boundary data both necessary and sufficient conditions for the mush to vanish are obtained. Possible behaviors of the transient phase for a twodimensional solution near a corner point of the domain are also investigated.
Quarterly of Applied Mathematics
This paper concerns morphological stability of a similarity solution to the Stefan problem with s... more This paper concerns morphological stability of a similarity solution to the Stefan problem with surface tension and initial supercooling. The linear stability analysis shows that for a nonzero surface tension each perturbation mode with a nonzero wave number is stable. However, the solution is unstable with respect to perturbations with a zero wave number limit point in their Fourier spectrum.
Current Opinion in Colloid & Interface Science
Scientific Reports, 2021
Osmosis-solution (solvent) flow through non-perfectly (perfectly) semipermeable membranes-is a fu... more Osmosis-solution (solvent) flow through non-perfectly (perfectly) semipermeable membranes-is a fundamental classical phenomenon of major practical importance. One of its potentially useful technological applications is the Pressure Retarded Osmosis (PRO) employed for energy harvesting from salinity variations 1. In this process the flow resulting from the osmotic pressure drop between fresh and saline water is used to drive a turbine. Unfortunately, at the current stage, in spite of its extreme simplicity and conceptual beauty, this process does not appear to be practically viable due to insufficient power efficiency 2. This assessment could be radically changed by the recently theoretically predicted "Breakthrough" operation mode of PRO 3. In this mode, the solute concentration at the interface between the porous support and the dense selective barrier layer of a non-perfect ('leaky') asymmetric membrane employed in PRO decreases with the increase of draw concentration, and, thus, the impeding effect of internal concentration polarization is eliminated, Fig. 1. The existence of this mode was predicted by Yaroshchuk based on the accurate analysis of the system of classical local Spiegler-Kedem-Katchalsky (SKK) equations of membrane transport with three constant coefficients for the barrier layer: solute permeability (diffusivity), solute reflection coefficient and hydraulic permeability 4. In a still more recent study Wu and Field 5 , contested the physical feasibility of "Breakthrough mode" and casted doubt upon the suitability of SKK equations with constant coefficients to PRO. In this note we re-derive the SKK equations based on a very simple capillary friction model of membrane transport in the dense barrier layer and identify the problem with the constant coefficients' assumption resulting in the occurrence of "Breakthrough mode". Our derivation results in recovering the SKK equations in the dilute solution limit, albeit with hydraulic permeability dependent on the local solute concentration in the barrier layer (modified SKK equations, MSKK). Taking into account this dependence, necessary for preserving the detailed force balance in the barrier layer, eliminates the existence of the "Breakthrough mode".
t,hrough ion exchange membranes. latter rule in favor of surface versus hl~c origin of overlimiti... more t,hrough ion exchange membranes. latter rule in favor of surface versus hl~c origin of overlimiting conductance along with those of recent experiments wit,h modified membranes. These linear convection, developing from the respective instability, are reported exchange membrane. Results of numerical calculation pertaining to nonof linear stability analysis of quiescent electrodiffusion.through a flat ion librium electroosmotic slip condition is recapitulated along with the results overlimiting conductance through the membrane. Derivation of nonequitroosmosis at, an ion exchange electrodialysis membrane, as a source of The paper is concerned with convection induced by nonequilibrium elec
Physical Review Fluids, 2017
Equilibrium electroconvective instability at a perfectly charge-selective solid, such as ion-exch... more Equilibrium electroconvective instability at a perfectly charge-selective solid, such as ion-exchange membrane or metal electrode, previously deemed impossible, is possible if one takes into account finite electrical conductivity of the solid. A simple model of electroconvective diffusion of ions in the depleted diffusion layer in this system predicts a supercritical transition to instability in the vicinity of the limiting current, as opposed to the subcritical transition for the previously studied nonequilibrium instability related to the extended space charge. The linear stability analysis in this model yields the division of the parameter space into domains in which each instability mechanism with its characteristic signatures dominates. Identification of the particular instability mechanism for a given system requires a detailed experimental study of the vicinity of the instability threshold in terms of both the voltage versus current dependence and flow visualization.
Physical Review Research, 2020
Hierarchical structure is an essential part of complexity, important notion relevant for a wide r... more Hierarchical structure is an essential part of complexity, important notion relevant for a wide range of applications ranging from biological population dynamics through robotics to social sciences. In this paper we propose a simple cellular-automata tool for study of hierarchical population dynamics.
Physical Review Fluids, 2020
Environmental Engineering Science, 2002
Russian Journal of Electrochemistry, 2017
Encyclopedia of Microfluidics and Nanofluidics, 2015
Physical review. E, Statistical, nonlinear, and soft matter physics, 2010
This paper is concerned with ionic currents from an electrolyte solution into a charge selective ... more This paper is concerned with ionic currents from an electrolyte solution into a charge selective solid, such as an electrode, an ion exchange membrane or an array of nanochannels in a microfluidic system. All systems of this kind have characteristic voltage-current curves with segments in which current nearly saturates at some plateau values due to concentration polarization--formation of solute concentration gradients under the passage of a dc current. A number of seemingly different phenomena occurring in that range, such as anomalous rectification in cathodic copper deposition from a copper sulfate solution, superfast vortexes near an ion-exchange granule, overlimiting conductance in electrodialysis and the recently observed nonequilibrium electro-osmotic instability, result from formation of an additional extended space charge layer next to that of a classical electrical double layer at the solid/liquid interface or, rather, from the peculiar features of the extended space charg...
Encyclopedia of Microfluidics and Nanofluidics, 2013
Physical Review Letters, 2011
We revisit the classical problem of diffusion-limited ion transport to a membrane (or electrode) ... more We revisit the classical problem of diffusion-limited ion transport to a membrane (or electrode) by considering the effects of charged side walls. Using simple mathematical models and numerical simulations, we identify three basic mechanisms for over-limiting current in a microchannel: (i) surface conduction carried by excess counterions, which dominates for very thin channels, (ii) convection by electro-osmotic flow on the side walls, which dominates for thicker channels and transitions to (iii) electro-osmotic instability on the membrane end in very thick channels. These intriguing electrokinetic phenomena may find applications in biological separations, water desalination, and electrochemical energy storage.
Atención Primaria, 2009
A shape phase transition between stable octupole deformation and octupole vibrations in Th nuclei... more A shape phase transition between stable octupole deformation and octupole vibrations in Th nuclei is analyzed in a microscopic framework based on nuclear density functional theory. The relativistic functional DD-PC1 is used to calculate axially-symmetric quadrupole-octupole constrained energy surfaces. Observables related to order parameters are computed using an interacting-boson Hamiltonian, with parameters determined by mapping the microscopic energy surfaces to the expectation value of the Hamiltonian in the boson condensate. The systematics of constrained energy surfaces and low-energy excitation spectra point to the occurrence of a phase transition between octupole-deformed shapes and shapes characterized by octupole-soft potentials.
APS Meeting …, 2010
A simple 1D locally electroneutral (LEN) electro-diffusive model explains steady-state fluidic re... more A simple 1D locally electroneutral (LEN) electro-diffusive model explains steady-state fluidic rectification in terms of asymmetry in the diffusion layers flanking a charge-selective element such as a porous membrane or nano-pore. The selectivity in such systems is a function of ...
Physical Review Fluids
Experimental and numerical results reveal a distinct signature of electroconvective instability i... more Experimental and numerical results reveal a distinct signature of electroconvective instability in the transient response for a microchannel-nanoslot system. We study the development of the electroconvective instability from equilibrium during the transient chronopotentiometric (galvanostatic operation) and chronoamperometric (potentiostatic operation) responses at overlimiting current conditions and observe a distinct signature of nonmonotonic transient response resulting from the emergence of electroconvective instability. This stands in contrast to previously reported experimental nonmonotonic transient responses in heterogeneous membrane systems associated with linear electroosmotic flow.
Quarterly of Applied Mathematics
Inexpensive highly permselective heterogeneous ion exchange membranes are prohibitively polarizab... more Inexpensive highly permselective heterogeneous ion exchange membranes are prohibitively polarizable by a direct electric current for use in electrodialysis. According to recent experiments, polarizability of these membranes may be considerably reduced by casting on their surface a thin layer of cross-linked polyelectrolyte, weakly charged with the same sign as the membrane’s charge. The present paper is concerned with this effect. In order to explain this feature, a simple limiting ion-exchange ’funnel’ model of a modified membrane is derived from the original two-layer model. In this model, asymptotically valid for a thin coating, solution of the ionic transport equations in it is replaced, via a suitable averaging procedure, by a single nonlinear boundary condition for the membrane/solution interface, which itself has the same order as the bulk equation. Rigorous analysis of the ’funnel’ model shows that the value of the limiting current through a modified membrane, which is the m...
Quarterly of Applied Mathematics
The disappearance of the mushy region in a multidimensional one-phase Stefan problem is discussed... more The disappearance of the mushy region in a multidimensional one-phase Stefan problem is discussed. In the case of a piecewise-smooth boundary of the domain and bounded initial-boundary data, sufficient conditions for the disappearance of the mushy zone in a finite time are presented. For a C-smooth boundary and appropriately smooth boundary data both necessary and sufficient conditions for the mush to vanish are obtained. Possible behaviors of the transient phase for a twodimensional solution near a corner point of the domain are also investigated.
Quarterly of Applied Mathematics
This paper concerns morphological stability of a similarity solution to the Stefan problem with s... more This paper concerns morphological stability of a similarity solution to the Stefan problem with surface tension and initial supercooling. The linear stability analysis shows that for a nonzero surface tension each perturbation mode with a nonzero wave number is stable. However, the solution is unstable with respect to perturbations with a zero wave number limit point in their Fourier spectrum.