Wydział Fizyki UW > Badania > Seminaria i konwersatoria > Soft Matter and Complex Systems Seminar

Soft Matter and Complex Systems Seminar

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Zapraszamy do sali 1.40, ul. Pasteura 5 o godzinie 09:30

Svyatoslav Kondrat (IChF PAN)

Low-dimensional Ionotronics: How Classical Models Reveal New Insights

Low-dimensional ionotronic systems exhibit captivating physics and find a range of technological applications, from capacitive energy storage and conversion to desalination and electroactuation. Despite their promise, these systems present significant challenges for investigation due to their inherent complexity and computational limitations [1]. In this talk, we will explore the application of analytically solvable statistical physics models to the study of nanostructured ionotronic systems. I will present insights from both lattice [2,3] and off-lattice [4] models, emphasizing their differences and relevance to phenomena such as ion ordering [5], quantum capacitance effects [6], and strategies for optimizing the performance of ionotronic-based devices [7,8,9]. I will particularly highlight results that are challenging to achieve with widely used molecular simulations, showcasing the unique utility and power of analytically solvable models.

Acknowledgements: This work was supported by the Polish National Science Centre (NCN) under grants Nos. 2021/40/Q/ST4/00160 and 2020/39/I/ST3/02199.

References
[1] Kondrat, Feng, Bresme, Urbach, and Kornyshev, Chem. Rev. 123, 6668 (2023)
[2] Kornyshev, Faraday. Disc. 164, 117-133 (2013)
[3] Lee, Kondrat, and Kornyshev, Phys Rev Lett. 113, 048701 (214)
[4] Verkholyak, Kuzmak, and Kondrat, J. Chem. Phys. 155, 174112 (2021)
[5] Groda, Dudka, Kornyshev, Oshanin, and Kondrat, J. Phys. Chem C. 125, 4968 (2021)
[6] Verkholyak, Kuzmak, Kornyshev, and Kondrat, J. Chem. Phys. Lett. 13, 10976 (2023)
[7] Janssen, Verkholyak, Kuzmak, Kondrat, J. Mol Liq. 371, 121093 (2023).
[8] Seltmann, Verkholyak, Gołowicz, Pameté, Kuzmak, Presser, and Kondrat, J. Mol. Liq. 391, 123369 (2023).
[9] Paolini, Antony, Raju, Kuzmak, Verkholyak, Kondrat, ChemElectroChem, e202400218 (2024).

Zapraszamy do sali 1.40, ul. Pasteura 5 o godzinie 09:30

Magdalena Mrokowska (IGF PAN)

Experimental insights into the sinking dynamics of solid particles in stratified aquatic systems

The settling of individual particles at low to moderate Reynolds numbers is a key mechanism for transporting particulate matter in oceans, seas, and lakes, which are often stratified by salinity- and temperature-driven density gradients. In such environments, particles exhibit complex behaviors, including transient dynamics and orientation instabilities. Density interfaces can also act as accumulation zones for biopolymers secreted by algae and bacteria, locally introducing non-Newtonian properties to the water column that further influence particle motion through viscoelastic and shear-dependent effects. These processes, though elusive in nature, are critical to understanding nutrient and carbon fluxes, microbial ecology, and pollutant transport.

To explore stratification effects, this presentation will demonstrate experimental results on disk settling through a two-layer water column with a non-linear density transition. The goal was to assess how stratification and disk shape influence settling velocity, reorientation behavior, and hydrodynamic interactions with wake. Flow visualization revealed five settling phases, marked by sequential reorientations and local velocity minima. Unique wake structures, including a bell-shaped one, were observed. Further experiments introduced model biopolymers to examine the combined impact of density and rheological gradients on the sinking of particles with various shapes. Results revealed that rheological gradients can play a dominant role in governing particle behavior. Overall, the findings raise further questions regarding the interplay of particle shape, stratification properties, and complex fluid rheology in sedimentation processes.

Zapraszamy do sali 1.40, ul. Pasteura 5 o godzinie 09:30

David Mackenzie (Ensemble3 Centre of Excellence, Warsaw)

Simulating the Electrical Properties of 2D Materials Using Finite Element Simulations

Two-dimensional (2D) materials, such as graphene and transition metal dichalcogenides, exhibit unique electrical properties that make them promising candidates for next-generation electronic and optoelectronic devices. In this talk, we will explore how finite element simulations can be used to provide insights into the extent which inhomogeneities affect the accuracy of standard electrical measurements of 2D materials. We will also discuss how unexpected behaviour from non-uniformity in layer number can be reproduced with these simulations, and how finite element simulations can be used to distinguish between ballistic and diffusive transport in high-quality graphene devices.

Zapraszamy do sali 1.40, ul. Pasteura 5 o godzinie 09:30

Miłosz Panfil (IFT UW)

What integrability and its breaking teaches us about the non-equilibrium quantum dynamics?

The non-equilibrium dynamics of quantum many-body systems exhibit a rich and complex phenomenology, as evidenced by recent advances in areas like eigenstate thermalization, quantum scars, generalized hydrodynamics, and quantum chaos. Among strongly correlated quantum models, integrable systems play a crucial role in providing a solid theoretical foundation for these concepts. These models are distinguished by an infinite number of conserved charges and stable quasi-particle excitations. When integrability is weakly broken, interactions between quasi-particles emerge, leading to the development of a novel kinetic theory. In this talk, I will review recent progress in this kinetic framework, which offers many insights into non-equilibrium phenomena of strongly interacting systems, including the emergence of the Navier-Stokes equations from quantum dynamics.

Zapraszamy do sali 1.40, ul. Pasteura 5 o godzinie 09:30

Dirk Schulze-Makuch (TU Berlin)

The Search for Life in the Universe

Life on Earth displays incredible diversity and occurs in nearly every extreme environment. The talk will show how this information will help us to search for life on other planets, even life as we do not know it. The emphasis will be placed on Mars, Jupiter´s moon Europa and Saturn´s moon Titan. Furthermore, in the talk I will highlight the major stages in the rise of microbial life to complex life on our planet and what this means for its presence on extraterrestrial planetary bodies. What are credible solutions to the Fermi Paradox and is intelligent alien life likely to be present in our cosmic neighborhood?

Zapraszamy do sali 1.40, ul. Pasteura 5 o godzinie 09:30

Piotr Szymczak (IFT UW)

On the ideal shapes of stalagmites

Stalagmites are column-like formations that rise from the floor of caves. They are formed by the buildup of minerals deposited from water dripping from the ceiling. The water dissolves minerals, such as calcium carbonate, from the rock above. As the water drips down, it loses carbon dioxide to the cave air. This causes the minerals to come out of solution and precipitate onto the cave floor, slowly building up the stalagmite.

Nearly sixty years ago, Franke formulated a mathematical model for the growth of stalagmites. In this model, the local growth rate of a stalagmite is proportional to the oversaturation of calcium ions in the solution dripping down the stalagmite's surface. Franke postulated that - provided the physical conditions in the cave remain constant - after a sufficiently long period, the stalagmite will assume an ideal shape, which in later stages of growth will only move upwards without further change in its form. These conclusions were later confirmed in computer simulations yet the mathematical form of this ideal shape was not discovered.

As we will show, Franke's model for stalagmite growth can be solved analytically, finding invariant, Platonic forms of stalagmites that could be observed in an "ideal cave", under constant physical conditions and with a constant flow of water dripping from an associated stalactite. Interestingly, it turns out that the shape numerically found in previous numerical studies is just one of a whole family of solutions. These new solutions describe stalagmites with a flat area at their peak of a certain fixed diameter, and conical stalagmites, with sharply pointed tops. All of these forms are observed in caves.

Zapraszamy do sali 1.40, ul. Pasteura 5 o godzinie 09:30

Maria Ekiel-Jeżewska (IPPT PAN)

Pierre-Gilles de Gennes

Nobel Prize in Physics 1991 "for discovering that methods developed for studying order phenomena in simple systems can be generalized to more complex forms of matter, in particular to liquid crystals and polymers": Pierre-Gilles de Gennes.

Zapraszamy do sali 1.40, ul. Pasteura 5 o godzinie 09:30

Jan Turczynowicz (IFT UW)

Encounter rate in marine snow dynamics

Oceans are vital carbon sinks, absorbing approximately 30% of anthropogenic carbon emissions. A portion of this carbon settles to the seafloor, reducing its presence in the short-term global cycle. The primary drivers of this vertical transport are sinking aggregates of dead phytoplankton, known as marine snow. To predict sedimentation dynamics, it is essential to understand encounters between sinking particles. Collisions between these particles promote aggregation, increasing their sedimentation velocity, while interactions with free-floating bacteria enhance dissolution, potentially slowing their descent. Models for encounter rates involve two dominant mechanisms of particle interception: advection and diffusion. The relative importance of these mechanisms depends on the sizes of the colliding particles. However, many existing studies either neglect one of these processes or simply superimpose them, raising concerns about their accuracy. Here, we present a systematic approach to modeling collision rates as a function of particle size and Peclet number.

Zapraszamy do sali 1.40, ul. Pasteura 5 o godzinie 09:30

Paweł Dłotko (IM PAN)

Topology in material physics

There is a strong connection between the structure and function of porous materials. Various properties, such as mechanical resistance, thermal conductivity, and more, are influenced not only by material’s composition but also by the shape of the porous structure of the material. In this talk, I will introduce several shape characteristics developed by my group and demonstrate how they can be use to analyze porous structures. In particular, I will discuss how the language of topology can be used to formalize certain physical properties, particularly in the context of sponge versus foam structures. Additionally, I will present examples of how topology can be used to study phase separations and transitions, constructing material landscapes, and expediting the synthesis of new materials.

Zapraszamy do sali 1.40, ul. Pasteura 5 o godzinie 09:30

King Ng (Institute of Physics, Polish Academy of Sciences)

Liquid droplet oscillations on a vibrating substrate

We study the oscillations of liquid droplets on substrates in macroscopic scale using Many-body Dissipative Particle Dynamics (MDPD). In this study, we focus on the harmonic droplet oscillations which are induced by sinusoidal forcing from horizonal substrate vibrations in one-dimension. Our investigation examines the topological changes of the droplet in various sizes and oscillation modes, considering different vibration frequencies and amplitudes. We also explore the role of the droplet's natural oscillation mode. Additionally, we demonstrate the effect of surface wettability on droplet oscillations, ranging from hydrophilic to hydrophobic surfaces, by parametrically tuning the equilibrium contact angles. Our MDPD simulations are compared with experimental results. This approach aims to optimize systems involving droplet movement driven by vibrating substrates.

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