Seminars
We will be hosting both in-person and virtual seminars.
Zoom Links will be provided on the calendar and through email.
Spring 2025
These meetings occur on Mondays from 4:00pm to 5:00pm
Virtual Zoom Seminars (unless otherwise indicated)
Monday 4:00pm
Virtual Zoom
(poster)
Martin Luther King Day (No Seminar)
Host:
Monday 4:00pm
Zoom Link
(poster)
Binghan Liu Virginia Tech
“Physical Mechanism and Control of Stratification in Drying Films of Colloidal Mixtures”
Stratification is an interesting and potentially useful non-equilibrium phenomenon that occurs in a film containing mixtures of colloids and polymers when it is rapidly dried. It is the outcome of complex interplay between a range of processes including evaporation, diffusion, absorption, phoresies, and osmosis that take place at the liquid-vapor interface, in the bulk of the film, and at the surface of the substrate. This dissertation employs large-scale molecular dynamics simulations to reveal the physical mechanisms driving stratification in drying films of polydisperse colloidal mixtures, based on the concept of Diffusiophoresis, where a colloidal particle migrates in response to the concentration gradient of other types of solute particles in the suspension. The results support the notion that the asymmetric diffusiophoretic response of small and large particles plays a key role in yielding a stratified colloidal film after rapid solvent evaporation. Further simulations show that the shape of particles can also influence their diffusiophoretic behavior. Therefore, stratification can occur in drying films containing particles with various shapes. Next, the dissertation demonstrates that a binary mixture of solvents possessing different volatilities can be used to drive a binary blend of colloidal articles of the same size to stratify through contrasting couplings between the particle and the solvent components. Finally, the dissertation explores the drying behavior of colloidal films in two dimensions and the results are compared with those in there dimensions. The results in this dissertation offer new insights into the physical mechanisms and control strategies of stratification in drying films of colloidal mixtures.
Host: Shengfeng Cheng
Monday 4:00pm
Zoom Link
(poster)
Prof. Pham Thang Virginia Tech, Material Engineering
“Nanostructured Quantum Materials: From Deterministic Synthesis to Multimodal Characterization”
Development of qubits in recent years has been underlined by advances through circuit design, device fabrication, and standardized metrology to systematically compare qubit performance created by different platforms. However, further improvement and especially, scalable manufacturing of qubits require a bottom-up approach in which one can control the assembly and interaction of atoms across different interfaces. This quest calls for advances in materials synthesis, characterization, processing, in addition to materials selection. In my talk, I will identify problems in quantum information science (QIS) which materials science and engineering can uniquely address. First, I will show my recent results in understanding the coherence-structure relationship in superconducting materials and qubits using multimodal electron microscopy. In the second part, I will discuss my efforts in designing a new quantum material platform, namely one-dimensional van der Waals materials with controlled morphology, chemistry and interface. Finally, I will introduce my research group at VT and how we are planning to develop data-driven materials synthesis and characterization for applications in QIS.
Host:
Monday 4:00pm
Zoom Link
(poster)
Mesfin Tsige University of Akron
"Computational Approaches to Understanding and Predicting Polymer Surface Properties"
The behavior of polymer surfaces and interfaces is crucial to the performance of advanced materials in coatings, adhesives, flexible electronics, and biomedical applications. Precise control over interfacial properties requires a molecular-level understanding of adhesion, wetting, and surface energetics. In this talk, I will present our computational efforts to investigate the wetting behavior of polymer surfaces using molecular dynamics (MD) simulations. By analyzing molecular structure, functional group orientations, and interfacial energetics, we gain key insights into the mechanisms that dictate polymer surface properties. Building on this foundation, I will discuss our recent integration of machine learning (ML) techniques to enhance the predictive capabilities of polymer surface properties. While MD simulations provide detailed molecular insights, their computational cost limits high-throughput screening. To address this, we have developed ML models trained on simulation and experimental data to efficiently estimate polymer surface tensions and interfacial characteristics. This hybrid approach, combining physics-based simulations with data-driven methods, provides a powerful framework for accelerating the design and optimization of polymeric interfaces.
Host: Shengfeng Cheng
Monday 4:00pm
Zoom Link
(poster)
Prof. Kimberly Weirich Clemson University
“Capillary-induced Biopolymer Network Formation and Remodeling”
From fluid transport in tubes and porous media to fiber aggregation, capillarity underlies a range of processes. Recently, protein condensates, which have properties of liquids, have emerged as important in regulating biological cellular organization. Based on their liquid properties, it has been hypothesized that the interactions of condensates with cellular surfaces, such as membranes and filaments, could induce mechanical deformations or higher-order structure formation via capillary-like interactions. A critical class of self-assembled cellular materials is the cytoskeleton, which is comprised of filaments canonically known to be cross-linked together by proteins into networks and bundles. The microstructure of these assemblies is particularly important, since the different microstructures each support particular physiological functions. Here, we show that protein condensates adsorb on actin filaments, evocative of drops of simple liquids on fibers. We investigate the condensate spreading and measure contact angle that condensates make with actin bundles. We find that condensates at the intersection of bundles cause capillary bridges which induce network remodeling, highlighting the role of capillarity in biological self-assembly. Understanding this bundling mechanism further could expand our toolkit for making self-assembled soft materials.
Host:
Monday 4:00pm
Zoom Link
(poster)
Burcu Gurbuz Johannes Gutenberg University Mainz
“Analyzing a Mathematical Model of a Reacting Diffusing System”
The behavior of ordinary differential equation (ODE) systems has been widely studied in various chemical reaction networks, including the well-known Calvin cycle. As a key component of the photosynthetic process, the Calvin cycle plays an important role in plant physiology by driving the conversion of carbon dioxide into organic compounds. This study focuses on modeling the Calvin cycle and analyzing the qualitative properties of its dynamical solutions. Using appropriately selected parameters, the system is studied to reveal its behavior under different conditions. The simulation results are presented through graphical plots that illustrate the dynamics of the system and provide insight into its function.
Host: Uwe Tauber
Monday 4:00pm
Zoom Link
(poster)
Prof. Nicholas Smith University of Maryland
Host:Giti Khodaparast
May 5
Monday 4:00pm
Zoom Link
(poster)
Peter Yunker George Tech
“Multicellular is Different”
Cells often live in groups, such as the surface attached communities of unrelated bacteria (e.g., biofilms) to multicellular organisms (e.g., animals). Living in groups provides cells with a range of biological benefits, but it also modifies their physics. Groups of cells are mechanically, topologically, geometrically, and functionally constrained by physical interactions. And, in the spirit of Philip Anderson, we often find that multicellular is different. In this talk I will discuss the emergent physics of multicellular growth in bacterial biofilms and lab evolved macroscopic snowflake yeast. In each case, we will see that multicellular growth cannot be understood without considering its physics.
Host: Shengfeng Feng
May 19
Monday 4:00pm
Zoom Link:
(poster)
Host:
May 26
Monday 4:00pm
Zoom Link:
(poster)
Memorial Day
Host:
Fall 2024
These meetings occur on Mondays from 4:00pm to 5:00pm
Virtual Zoom Seminars (unless otherwise indicated)
Monday 4:00pm
Zoom Link
(poster)
Matthew Asker University of Leeds
Fixation and Extinction in Fluctuating Meta-populations with Migration Subject to Bottlenecks
Microbial populations evolve within spatially structured and dynamically changing environments, a reality often overlooked by classical modelling approaches. From microbial infections spreading across host organs to environmental pollutants altering ecological niches, understanding the effects of and interplay between spatial structure and environmental change is essential for developing insights into the evolutionary dynamics of microbial communities. Here, we present a comprehensive analysis of a two-species metapopulation model, incorporating selection bias, to investigate how microbial species evolve while competing under stochastic population bottlenecks. Our analytical framework provides insights into the long-lived behavior of the system: will we see total extinction of all species, or will a species take over and remain, and how long does this take? Additionally, stochastic simulations offer a deeper understanding of the complex dynamics on various networks, extending beyond the scope of analytical predictions where we find the qualitative behavior remains. By combining analytical and computational methodologies, we uncover the rich dynamics underlying microbial population evolution in spatially structured and dynamically changing environments.
Host: Prof. Uwe Tauber
Spring 2024
These meetings occur on Mondays from 4:00pm to 5:00pm
Virtual Zoom Seminars (unless otherwise indicated)
Monday 4:00pm
Virtual Zoom
(poster)
Host:
Monday 4:00pm
Zoom Link
(poster)
Prof. Marija Vucelija
University of Virginia
Host:Giti Khodaparast
Monday 4:00pm
Zoom Link
(poster)
Joint Seminar
Prof. Elham Ghadiri Wake Forest University
Host: Giti Khodaparast
May 22
Monday 4:00pm
Zoom Link: https://virginiatech.zoom.us/j/84066367405
(poster)
Prof. Alastair Rucklidge
University of Leeds, Germany
"Cycling behavior and spatial structure in a hetero-clinic network model of Rock-Paper-Scissors-Spock-Lizard
The well-known game of Rock-Paper-Scissors can be used as a simple model of competition between three species. When modeled in continuous time using ordinary differential equations, the resulting system contains a hetero-clinic cycle between the three equilibrium solutions that represent the existence of only a single species. The game can be extended in asymmetric fashion by the addition of two further strategies (`Spock' and `Lizard'):now each strategy is dominant over two of the other four strategies, and is dominated by the remaining two. The ODE model contains coupled hetero-clinic cycles forming a hetero-clinic network. We develop a technique, based on the concept of fragmentary asymptotic stability, to understand the stability of arbitrarily long periodic sequences of visits made to the neighborhoods of the equilibrium. The regions of stability form a complicated pattern in parameter space. By adding spatial diffusion, we extend to a partial differential equation model and investigate the spatiotemporal evolution of these periodic itineraries.
Host: Prof. Uwe Tauber