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Program Highlights

UPENN IRG2 Vimentin filaments protect cell nuclei from mechanical damage

Cells and tissues are subjected to external mechanical stresses in the body, including compressive loads, pressure gradients, and shear. This study shows that single cells become harder when compressed and that the parts inside the cells that make them strong (called the cytoskeleton) change when they are compressed. Some cells, like fibroblasts, become harder when subjected to moderate compression. However, this does not happen if a part of the cytoskeleton called vimentin is removed. This is because vimentin networks become harder when compressed or extended. This is explained using a theoretical model to based on the flexibility of vimentin filaments and their surface charge, which resists volume changes of the network under compression.

Fabricating Granular Hydrogels for 3D Printing

Granular hydrogels are jammed assemblies of hydrogel microparticles (i.e., “microgels”) widely explored in biomedical applications due to promising features such as shear-thinning to permit injectability and inherent porosity for cellular interactions. One area where this is particularly promising is in 3D printing. 

Uncovering the Surprising Nature of Glassy Energy Landscapes

UPenn researchers explored the potential energy landscapes of three different glassy and glass-forming model systems in simulation; discovering that the lowest energy glassy states of the system have an unexpected arrangement in high-dimensional configuration space.  Specifically, rather than being randomly scattered and separated by steep and tall energy barriers (akin to the lowest points in an Alpine landscape), the states were arranged into quasi-one-dimensional clusters, crumpled into a fractal shape, with only small barriers between them (akin to the low-lying points along the floor of the Grand Canyon). 

Toughening Infiltrated Nanoparticle Packings: Role of Bridging and Entanglement

Researchers at UPenn investigate the fracture behavior of disordered polymer-infiltrated nanoparticle films (PINFs). Here, the extent of polymer confinement in PINFs was tuned over three orders of magnitude NPs of varying size and polymers with varying molecular weight. The results show that brittle, low molecular weight (MW) polymers can significantly toughen NP packings, and this toughening effect becomes less pronounced with increasing NP size. 

MEM-C IRG-2: Nematic Fluctuations in an Orbital Selective Superconductor Fe1+yTe1-xSex

Electronic  nematicity  is  a  correlated  electronic  state  in  solids  that spontaneously breaks rotational symmetry. This work found that in Fe1+yTe1-xSex,  one  of  the  most  strongly  correlated  iron-based superconductors,   electronic   nematicity   is   closely   linked   to magnetism,   and   its   fluctuations   may   be   responsible   for superconducting pairing.

MEM-C IRG-1: Patterning Nanocrystals on Photonic Cavities with Electrohydrodynamic Inkjet Printing

Electrohydrodynamic ink jet printing has been used to print  CsPbBr3 nanocrystals into very small features, with spot sizes down to only a few hundred nanometers across. The nanocrystals survive the printing, and even spontaneously self-organize into superlattices.

Capillary forces and biomolecular condensates: Structure and function

Princeton researchers have demonstrated the physical principles of capillarity, including examples of how capillary forces structure multiphase condensates and remodel biological substrates. As with other mechanisms of intracellular force generation (e.g. molecular motors), capillary forces can influence biological processes. Identifying the biomolecular determinants of condensate capillarity represents an exciting frontier, bridging soft matter physics and cell biology.

NSF Big Idea
Understanding the Rules of Life

Unlocking High Capacity and Fast Na+ Diffusion of HxCrS2 by Proton-Exchange Pretreatment

Princeton researchers have demonstrated that acid pre-treatment of NaCrS2 to form a new phase (named HxCrS2) results in significant improvements to the material’s performance as a sodium battery electrode.

NSF Big Idea
Quantum Leap

Proximity-induced superconductivity in epitaxial topological insulator/superconductor heterostructures

The search for an unusual form of superconductivity known as topological superconductivity has attracted a great deal of attention of the quantum materials community because of its fundamental novelty and potential applications in fault-tolerant quantum computing technology.

Electrocaloric Effect of Perovskite High Entropy Oxide Films

Pb(Hf0.2Zr0.2Ti0.2Nb0.2X0.2)O3, a high-entropy perovskite, undergoes an entropy-driven phase transformation when X=Mn while X=Al always contains minor second phases in bulk ceramics.

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