Le Qiao

Inside a cell, there are tiny liquid droplets, like oil droplets in water. They form from proteins and RNA and serve all sorts of purposes, from storing molecules to speeding up reactions. But if droplets start merging with each other, you'd end up with one big puddle, which would wreck the cell's organization.

Layered polymers resemble a multi-story building where each floor is painted a different color, and sometimes cracks appear between floors. These cracks are dislocation pairs, which are periodic irregularities that spoil the material. Engineers have long sought ways to control such defects without rebuilding the entire structure.