Interevent-time distribution and aftershock frequency in non-stationary induced seismicity.

The initial footprint of an earthquake can be extended considerably by triggering of clustered aftershocks. Such earthquake-earthquake interactions have been studied extensively for data-rich, stationary natural seismicity. Induced seismicity, however, is intrinsically inhomogeneous in time and space and may have a limited catalog of events; this may hamper the distinction between human-induced background events and triggered aftershocks.

Rheology across the zero-temperature jamming transition.

Many soft-matter systems show a transition between fluidlike and mechanically solidlike states when the volume fraction of the material, e.g., particles, drops, or bubbles is increased.

Intermittent dynamics in transient polymer networks under shear: signs of self-organized criticality.

In this paper we demonstrate an unusual behavior in the shear-banded flow of a viscoelastic fluid. We report large and patterned fluctuations in the shear stress in an apparently fluid material undergoing steady shear, which we interpret as an intermittent and microscopic fracture and self-healing process. The statistical pattern of the fluctuations is indicative of self-organized criticality, and their magnitude can be directly related to the constitutive instability that underlies the shear banding.

Nanoscale morphology of high-performance polymer solar cells.

Transmission electron microscopy and electron diffraction are used to study the changes in morphology of composite films of poly(3-hexylthiophene) (P3HT) and a methanofullerene derivative (PCBM) in bulk heterojunction solar cells. Thermal annealing produces and stabilizes a nanoscale interpenetrating network with crystalline order for both components. P3HT forms long, thin conducting nanowires in a rather homogeneous, nanocrystalline PCBM film.