A5009243715- Granular flow and fluidized beds
- Material Dynamics and Properties
- Micro and Nano Robotics
- Rheology and Fluid Dynamics Studies
- Sports Dynamics and Biomechanics
- Landslides and related hazards
- Force Microscopy Techniques and Applications
- Microfluidic and Bio-sensing Technologies
- Bacterial biofilms and quorum sensing
- Advanced Materials and Mechanics
- Cellular and Composite Structures
- Cellular Mechanics and Interactions
- Ultrasonics and Acoustic Wave Propagation
- Bacteriophages and microbial interactions
- Pickering emulsions and particle stabilization
- Acoustic Wave Phenomena Research
- Fluid Dynamics Simulations and Interactions
- Biomimetic flight and propulsion mechanisms
- Material Properties and Processing
- Lattice Boltzmann Simulation Studies
- Photoreceptor and optogenetics research
- Lipid Membrane Structure and Behavior
- NMR spectroscopy and applications
- Geotechnical Engineering and Soil Mechanics
- Engineering and Material Science Research
Princeton University
2020-2025
Nanyang Technological University
2023
University of Chicago
2016-2022
School of the Art Institute of Chicago
2019-2020
University of Manchester
2012-2017
A remarkable property of dense suspensions is that they can transform from liquid-like at rest to solid-like under sudden impact. Previous work showed this impact-induced solidification involves rapidly moving jamming fronts; however, details process have remained unresolved. Here we use high-speed ultrasound imaging probe non-invasively how the interior a suspension responds Measuring speed sound demonstrate proceeds without detectable increase in packing fraction, and evolving flow field...
Significance While many bacteria can sense the presence of a surface, mechanical properties different surfaces vary tremendously and be as rigid bone or soft mucus. We show that pathogen Pseudomonas aeruginosa distinguishes by stiffness transcriptionally tunes its virulence to surface rigidity. This connection between pathogenicity infection site presents an interesting potential for clinical applications. The mechanism behind sensing relies on retraction external appendages called type IV...
Living tissues are an integrated, multiscale architecture consisting of dense cellular ensembles and extracellular matrices (ECMs). The cells ECMs cooperate to enable specialized mechanical properties dynamic responsiveness. However, the living difficult replicate. A particular challenge is identification a cell-like synthetic component, which tightly integrated with its matrix also responsive external stimuli. Here, we demonstrate that cellular-scale hydrated starch granules, underexplored...
Abstract Colonies of the social bacterium Myxococcus xanthus go through a morphological transition from thin colony cells to three-dimensional droplet-like fruiting bodies as strategy survive starvation. The biological pathways that control decision form body have been studied extensively. However, mechanical events trigger creation multiple cell layers and give rise droplet formation remain poorly understood. By measuring orientation, velocity, polarity, force with cell-scale resolution, we...
We study the fronts that appear when a shear-thickening suspension is submitted to sudden driving force at boundary. Using quasi-one-dimensional experimental geometry, we extract front shape and propagation speed from flow field map out their dependence on applied shear. find relation between stress velocity quadratic, as generally true for inertial effects in liquids, but with pre-factor can be much larger than material density. show these findings explained by an extension of Wyart-Cates...
Unlike dry granular materials, a dense suspension like cornstarch in water can strongly resist extensional flows. At low extension rates, such behaves viscous liquid, but rapid results response where stresses far exceed the predictions of lubrication hydrodynamics and capillarity. To understand this remarkable mechanical response, we experimentally measure normal force imparted by large bulk on plate moving vertically upward at controlled velocity. We observe that above velocity threshold,...
A bstract Integrins are crucial for eukaryotic cell attachment and motility within the extracellular matrix (ECM) via focal-adhesion formation, with their evolutionary emergence important development of multicellularity. Intriguingly, single gliding cells predatory deltaproteobacterium Myxococcus xanthus form bacterial (bFA) sites; therein, helically-trafficked motors become immobilized at anchored locations through Glt apparatus association cell-surface integrin αI-domain-like adhesin CglB....
The results of an experimental investigation into the elastic buckling a soft cellular solid using magneto-static loading are reported. An electromagnet was used to apply controlled force elastomer with embedded rare earth magnets. resulting strain found induce above critical applied field strength. instability resulted in rapid rotation sample which indicates potential as fast switching mechanism for materials.
A key parameter describing the behavior of suspensions is volume fraction ϕ solid particles that are dispersed in liquid. Obtaining accurate values for becomes difficult porous particles, because they can absorb some prime example widely used cornstarch suspensions, which usually only estimated from mass particles. Here we present a method to measure effective porosity and compressibility with ultrasound. We obtain speed sound dilute at multiple particle concentrations different solvent...
The drag force exerted on an object intruding into granular media can depend the object's velocity as well depth penetrated. We report intrusion experiments at constant speed over four orders in magnitude together with systematic molecular dynamics simulations beyond quasi-static regime. find that dependence crosses to a characteristic time after initial impact. This crossover scale, which depends penetration speed, depth, gravity and intruder geometry, challenges current models assume...
Significance We demonstrate a centimeter-scale swimmer that converts direct current electric power into thrust in the low Reynolds number regime with minimal design and engineering. The swimmers show multiple forms of motion despite their simple geometry, which are reminiscent some swimming microorganisms nature. map state diagram to reveal how translate rotate they switch between these different motion. Finally, our experiments confirm theoretically predicted self-oscillation such systems...
The results of an experimental investigation into the motion linked spheres at low Reynolds number are presented. Small permanent magnets were embedded in and torques generated by application external magnetic field. Pairs neutrally buoyant spheres, connected either glass rods or thin elastic struts, move a reciprocal orbit when driven oscillatory An array three struts buckles periodic, non-reciprocal manner. induced magneto-elastic buckling propels elemental swimmer we find that geometrical...
Dense suspensions of hard particles in a Newtonian liquid can be jammed by shear when the applied stress exceeds certain threshold. However, this jamming transition from fluid into solidified state cannot probed with conventional steady-state rheology because distribution inside material controlled sufficient precision. Here we introduce and validate method that overcomes obstacle. Rapidly propagating fronts are generated used to establish well-controlled local conditions sweep across...
We consider nonlinear elastic deformations of a magneto-elastic beam, using combined experimental and theoretical approach. In the experiments, beam had one end clamped with magnet attached at its free end. When it was placed in an external magnetic field, susceptible to Euler buckling. However, classic supercritical bifurcation associated this buckling became subcritical when attracting introduced close proximity beam. To understand these we develop model that couples elastica dipole...
High-speed ultrasound imaging is used to reconstruct the three-dimensional flow field of dense cornstarch suspensions under tilted impact. Experiments show how jamming fronts propagate and get deformed in a nonaxisymmetric manner different impact angles.
The impact of single passive intruders into granular particles has been studied in detail. However, the force produced by multiple separated at a distance from one another, and hence effect their presence close proximity to is largely unexplored. Here, we use numerical simulations laboratory experiments study response two parallel rods intruding vertically media while varying gap spacing between them. We also explored variations friction, intruder size, particle size on response. net work...
Disordered-Network Mechanical Materials (DNMM), comprised of random arrangements bonds and nodes, have emerged as mechanical metamaterials with the potential for achieving fine control over their properties. Recent computational studies demonstrated this whereby an extremely high degree tunability can be achieved in disordered networks via a selective bond removal process called pruning. In study, we experimentally demonstrate how pruning network alters its macroscopic dynamic response...
Abstract The ability of eukaryotic cells to differentiate substrate stiffness is fundamental for many processes such as the development stem into mature tissue. Here, we establish that bacteria feel their microenvironment in a similar manner. We show Pseudomonas aeruginosa actively probes and measures using type IV pili (TFP). activity major virulence factor regulator Vfr peaked with physiologically important range between 0.1 kPa (mucus) 1000 (cartilage). local concentration PilA at base...
Colonies of the social bacterium Myxococcus xanthus go through a morphological transition from thin colony cells to three-dimensional droplet-like fruiting bodies as strategy survive starvation. The biological pathways that control decision form body have been studied extensively. However, mechanical events trigger creation multiple cell layers and give rise droplet formation remain poorly understood. By measuring orientation, velocity, polarity, force with cell-scale resolution, we reveal...
Improving the solar-to-hydrogen efficiency has always been a significant topic in field of photocatalysis. Based on first-principles calculations, herein, we propose multiple strategies to improve photocatalytic properties 2D arsenic sesquichalcogenides for full water splitting. The new configurations As2STe2 and As2SeTe2 monolayers, derived from As2Te3 monolayers by surface modification, are manifested be typical infrared-light driven photocatalysts. Notably, under built-in electric field,...