Article
Chemistry, Physical
Roni Kroll, Yoav Tsori
Summary: We propose a model that describes ion-induced nucleation in fluids, which can be induced by various charged particles such as molecular aggregates, large ions, colloids, or aerosol particles. This model extends the Thomson model to polar environments and solves the Poisson-Boltzmann equation to determine the potential profiles and energy around the charged core. Our results are analytical under the Debye-Huckel limit and numerical otherwise. By analyzing the Gibbs free energy curve, we identify the metastable and stable states, as well as the energy barrier between them, under different saturation values, core charges, and salt concentrations. Additionally, we calculate the phase lines in the phase diagram of supersaturation and core charge, revealing different regions of electro-prewetting, spontaneous nucleation, ion-induced nucleation, and classical-like nucleation.
JOURNAL OF COLLOID AND INTERFACE SCIENCE
(2023)
Article
Mechanics
Raul Fernandez-Mateo, Pablo Garcia-Sanchez, Victor Calero, Hywel Morgan, Antonio Ramos
Summary: Quadrupolar electro-osmotic flows are experimentally demonstrated around charged dielectric microspheres in an electrolyte under an alternating current electric field. An electrokinetic model is presented to predict flow characteristics based on surface conductance and polarization of electrolyte concentration. These flows, known as concentration polarization electro-osmosis, are anticipated to play a major role in the assembly of colloids and manipulation of dielectric micro- and nanoparticles through electric fields.
JOURNAL OF FLUID MECHANICS
(2021)
Article
Physics, Multidisciplinary
Chun-Jen Chen, Clemens Bechinger
Summary: Many animal species organize in groups to achieve advantages, and this study demonstrates that robotic swarms can also escape from hazardous areas through cooperative group formation, even in the presence of incomplete individual information.
NEW JOURNAL OF PHYSICS
(2022)
Article
Physics, Multidisciplinary
Ioulia Chikina, Sawako Nakamae, Valeriy Shikin, Andrey Varlamov
Summary: The Seebeck effect in stabilized electrolytes containing colloidal particles exhibits a unique two-stage character, with a linear increase followed by a dramatic drop in differential thermopower. This behavior is attributed to the thermo-diffusion flows of mobile ions and the involvement of colloidal particles in forming the electric field. The steady state thermoelectric effect is characterized by slow thermal diffusion of colloidal particles and loss of their electro-neutrality near electrodes.
Article
Multidisciplinary Sciences
Marjolein N. van der Linden, Jeffrey C. Everts, Rene van Roij, Alfons van Blaaderen
Summary: This study demonstrates experimentally that the Brazil-nut effect can be achieved in a system of charged colloids driven by Brownian motion and electrostatics without external forces. Theoretical analysis shows that the mass-per-charge ratio of the heavier particles must be smaller than that of the lighter particles, and at high overall density, the system can be trapped in a long-lived metastable state, preventing the occurrence of the equilibrium Brazil-nut effect. This work provides valuable insights into the physics of strongly interacting systems and has implications for understanding sedimentation experiments with charged colloids.
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
(2023)
Article
Chemistry, Physical
Mohit Singh, Yoav Tsori
Summary: In this study, the orientation transitions of uncharged peanut-shaped polystyrene colloids under different electric field conditions were investigated experimentally and theoretically. The results show that the colloids exhibit different orientation states depending on the applied potential and electric field frequency.
COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS
(2022)
Article
Multidisciplinary Sciences
Bokusui Nakayama, Hikaru Nagase, Hiromori Takahashi, Yuta Saito, Shogo Hatayama, Kotaro Makino, Eiji Yamamoto, Toshiharu Saiki
Summary: Indirect interactions via shared memory deposited on the field play a crucial role in collective motions. We propose a pheromone-based autonomous agent system that mimics the collective behavior of ants and bacteria. This system combines the phase-change behavior of self-propelled Janus particles and AC electroosmotic flow to create pheromone-like trails that attract other particles.
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
(2023)
Article
Materials Science, Multidisciplinary
Kitinan Pongsangangan, T. Ludwig, H. T. C. Stoof, Lars Fritz
Summary: This paper studies the thermoelectric transport in interacting two-dimensional Dirac-type systems using a phenomenological Boltzmann approach. It considers electron-hole hydrodynamics and proposes a unique type of hydrodynamics that consists of electrons, holes, and plasmons. The transport properties, especially the thermoelectric behavior, are investigated.
Article
Physics, Multidisciplinary
J. Bocanegra-Flores, C. Haro-Perez, D. Reyes-Contreras, L. F. Rojas-Ochoa
Summary: This study investigates the kinetics of crystallization of charged microgels suspensions of PNIPAM at low ionic strength, finding that the crystal growth rate strongly depends on the quenching temperature.
FRONTIERS IN PHYSICS
(2022)
Article
Physics, Fluids & Plasmas
A. Scotti, M. Pelaez-Fernandez, U. Gasser, A. Fernandez-Nieves
Summary: The osmotic pressure of both ionic and neutral microgel solutions is primarily determined by the behavior of free ions leaving the microgel periphery to maximize entropy, rather than the translational degrees of freedom of the microgels themselves. Microgels are energetically favorable to maintain a constant volume without significant deswelling up to a certain concentration. The concentration at which deswelling begins weakly depends on the crosslinker concentration, which impacts microgel size; this can be explained by examining the relationship between osmotic pressure, microgel bulk modulus, and particle size.
Article
Chemistry, Physical
Mohammad Shoaib, Shaihroz Khan, Omar Bashir Wani, Ahmed Abdala, Ali Seiphoori, Erin R. Bobicki
Summary: This study investigates the impact of pH-mediated colloidal particle-particle interaction on the properties of sodium-montmorillonite suspensions. The experimental results reveal significant effects of pH on the aging, viscoelastic response, and yield stress behavior of the suspensions.
JOURNAL OF COLLOID AND INTERFACE SCIENCE
(2022)
Article
Physics, Multidisciplinary
S. N. Klimin, J. Tempere, T. Repplinger, H. Kurkjian
Summary: This study investigates collective excitations in the superfluid state of Fermi condensed charged gases. It examines the dispersion and damping of collective excitations at nonzero temperatures, and considers the coexistence and interaction of different branches of collective excitations: plasma oscillations, pair-breaking Higgs modes, and Carlson-Goldman phonon-like excitations. The path integral methods for superfluid Fermi gases and for Coulomb gas are combined into a unified formalism to account for plasmonic modes. The spectra of collective excitations are determined in two ways: from the spectral functions and from the complex poles of the fluctuation propagator. A resonant avoided crossing of different modes is shown, accompanied by resonant enhancement of the response provided by the pair-breaking modes due to their interaction with plasma oscillations, which may facilitate the experimental observation of the pair-breaking modes.
NEW JOURNAL OF PHYSICS
(2023)
Article
Chemistry, Multidisciplinary
Yifei Wang, Sheereen Majd
Summary: Phase separation in lipid membranes is controlled by the presence and amount of charged lipids. This study shows that the inclusion of charged lipids with saturated tails can suppress phase separation in multicomponent membranes. The effect is dependent on the membrane surface charge density and can be neutralized by the inclusion of oppositely charged lipids or divalent cations.
Article
Chemistry, Physical
Martin Wagner, Sergi Roca-Bonet, Marisol Ripoll
Summary: The study demonstrates that colloids driven by phoresis play a crucial role in the design of synthetic microswimmers, as their specific interactions significantly influence the dynamics of the swimmers. Simulations show that the phoretic character and relative size of beads strongly impact the resulting solvent velocity fields, leading to different behaviors of dimeric Janus active colloids. Additionally, hydrodynamic flows can transition from puller-type to pusher-type, creating unique phenomena in three-dimensional bulk conditions.
EUROPEAN PHYSICAL JOURNAL E
(2021)
Article
Biochemistry & Molecular Biology
Frederico Prudente, Jorge M. C. Marques
Summary: This study investigates the structural transitions and dissociation phenomenon in charged colloidal clusters using computational simulations. Parallel tempering Monte Carlo simulations are used to calculate the heat capacity and classify the structures based on their energy levels. The study finds that peaks or shoulders on the heat-capacity curve serve as thermodynamic signatures of dissociation and structural transitions, and the occurrence of dissociation is temperature-dependent while the structural transitions are size-dependent for the colloidal system.
Article
Physics, Multidisciplinary
Alois Wuerger
Summary: The huge Seebeck coefficients observed recently for ionic conductors are shown to arise from a ratchet effect where activated jumps between neighbor sites are rectified by a temperature gradient, thus driving mobile ions toward the cold. For complex systems with mobile molecules like water or polyethylene glycol, there is an even more efficient diffusiophoretic transport mechanism, proportional to the thermally induced concentration gradient of the molecular component. Without free parameters, the model describes experiments on the ionic liquid EMIM-TFSI and hydrated NaPSS, and qualitatively accounts for polymer electrolyte membranes with Seebeck coefficients of hundreds of k(B)/e.
PHYSICAL REVIEW LETTERS
(2021)
Article
Physics, Multidisciplinary
Z. Zhang, Y. Wang, Y. Amarouchene, R. Boisgard, H. Kellay, A. Wurger, A. Maali
Summary: By measuring the thermal capillary oscillations of a hemispherical liquid gas interface using an atomic force microscope, the characteristics of the interface, including surface viscosity and contact line pinning, can be studied. Minute amounts of impurities are found to alter the rheology of the pure water surface.
PHYSICAL REVIEW LETTERS
(2021)
Article
Mechanics
Harinadha Gidituri, Alois Wurger, Kevin Stratford, Juho S. Lintuvuori
Summary: In this study, dynamics of a spherical colloidal particle pulled along the fluid-fluid interface were investigated using lattice Boltzmann simulations. Results showed that hydrodynamic drag decreases and particle rotation increases when the particle is more in the low viscosity fluid.
Article
Multidisciplinary Sciences
Falko Schmidt, Hana Sipova-Jungova, Mikael Kaell, Alois Wuerger, Giovanni Volpe
Summary: Active nanoparticles in a critical solution show behavior far from equilibrium, with fast orbital rotations observed around the beam axis even with an increase in effective temperature.
NATURE COMMUNICATIONS
(2021)
Review
Chemistry, Multidisciplinary
Matteo Massetti, Fei Jiao, Andrew J. Ferguson, Dan Zhao, Kosala Wijeratne, Alois Wuerger, Jeffrey L. Blackburn, Xavier Crispin, Simone Fabiano
Summary: The study of thermoelectric materials has shifted towards the use of carbon-based semiconductors, which are attracting attention due to their high abundance of atomic elements, easy processing, and low thermal conductivity. Constant discoveries of new materials and concepts have expanded the applications of thermoelectric materials. This review is divided into three sections, covering the basic principles of thermoelectric effects, efforts on developing devices utilizing these effects, and investigations on state-of-the-art thermoelectric materials.
Article
Chemistry, Physical
Sadman Shakib, Benoit Rogez, Samira Khadir, Julien Polleux, Alois Wurger, Guillaume Baffou
Summary: Thermophoresis refers to the motion of particles along temperature gradients, which can be crucial in applications involving nano- and microscale heating. Recent studies have observed significant thermophoresis in nanoplasmonic applications and introduced a novel method for quantifying this effect.
JOURNAL OF PHYSICAL CHEMISTRY C
(2021)
Article
Physics, Fluids & Plasmas
Harinadha Gidituri, Zaiyi Shen, Alois Wurger, Juho S. Lintuvuori
Summary: This study investigates the orientational and translational dynamics of spherical microswimmers trapped at fluid interfaces. The force dipole component exerts a torque, aligning pushers parallel to the interface and pullers in the normal direction. The source dipole component results in particle rotation only for a finite viscosity contrast between the two fluids. The superposition of these two contributions leads to a rotational dynamics with different steady-state orientations.
PHYSICAL REVIEW FLUIDS
(2022)
Article
Physics, Fluids & Plasmas
Petch Khunpetch, Arghya Majee, Ruixuan Hu, Rudolf Podgornik
Summary: By analyzing the composition of solvent accessible, embedded, dissociable, charge-regulated moieties, we studied the changes in the vicinal acidity (pH) at a spherical amphiphilic membrane. Utilizing the linear Debye-Huckel approximation, nonlinear Poisson-Boltzmann theory, and the Frumkin-Fowler-Guggenheim adsorption isotherm model, we investigated the dependence of local pH on position, as well as bulk electrolyte concentration, bulk pH, and membrane curvature. Our findings demonstrate a strong agreement with experimental data when appropriate adsorption parameters are chosen.
Article
Chemistry, Physical
Hu Ruixuan, Arghya Majee, Jure Dobnikar, Rudolf Podgornik
Summary: This study investigates the interaction between two charge regulating spherical macroions with dielectric interior and dissociable surface groups in a monovalent electrolyte solution. The research finds symmetry breaking transitions from symmetric to asymmetric charge distribution, resulting in annealed charge patchiness and like-charge attraction even in a univalent electrolyte.
EUROPEAN PHYSICAL JOURNAL E
(2023)
Article
Chemistry, Multidisciplinary
Ayesha Sultana, Alois Wurger, Ziyauddin Khan, Mingna Liao, Magnus P. Jonsson, Reverant Crispin, Dan Zhao
Summary: This study investigates the mechanism of thermal voltages in ionic thermoelectric materials and finds that the concentration gradient significantly affects the thermal voltage in polyelectrolytes. The hydration of different cations influences the water concentration gradient, affecting the barrier height and ion-induced potential in the electrodes. The results demonstrate that the thermal voltage can be an order of magnitude larger than the contribution from thermoeffusion-induced potentials in ionic thermoelectric devices, particularly in ionic thermoelectric supercapacitors.
Article
Physics, Fluids & Plasmas
Marcela Rodriguez Matus, Zaicheng Zhang, Zouhir Benrahla, Arghya Majee, Abdelhamid Maali, Alois Wuerger
Summary: The study investigates electroviscous phenomena in a nanoscale capillary resulting from charge-flow coupling, using a theoretical approach based on Poisson-Boltzmann mean-field theory. The research presents a quantitative description of the electroviscous drag coefficient and electrostatic repulsion in a confined water film, with surface charge density as the only free parameter.
Article
Materials Science, Multidisciplinary
A. Sultana, A. Wurger, J. Phopase, X. Crispin, D. Zhao
Summary: Ionic thermoelectric materials can generate high thermal voltage under small temperature differences due to their large Seebeck coefficient. Understanding the mechanism of the Seebeck coefficient in practical electrolytes is still a main challenge.
JOURNAL OF MATERIALS CHEMISTRY C
(2022)
Article
Chemistry, Physical
Petch Khunpetch, Arghya Majee, Rudolf Podgornik
Summary: We present a theory of electrostatic interactions in lipid bilayer membranes with dissociable moieties subjected to charge regulation in both monolayer leaflets. We investigate the relationship between membrane curvature and charge regulation in a lipid bilayer vesicle using linear Debye-Huckel (DH) and non-linear Poisson-Boltzmann (PB) theories. Our findings show that charge regulation can induce charge symmetry breaking, non-linear flexoelectricity, and anomalous curvature dependence of free energy in an otherwise symmetric bilayer membrane. The pH effects studied go beyond the traditional understanding of electrostatic renormalization in membrane mechano-elastic properties.
Proceedings Paper
Materials Science, Multidisciplinary
Falko Schmidt, Giovanni Volpe, Hana Sipova-Jungova, Mikael Kall, Alois Wurger
OPTICAL MANIPULATION AND STRUCTURED MATERIALS CONFERENCE 2021
(2021)
