Temporal Refraction in an Acoustic Phononic Lattice.

In this Letter, we present the first experimental demonstration of the temporal refraction of acoustic waves in a phononic lattice. A step change in grounding stiffness results in a discontinuous change in group velocity across a so-called temporal boundary. This leads to frequency translation of incident signals, which maintain constant wavelength.

Elasticity and failure of liquid marbles: influence of particle coating and marble volume.

When coated with microscale hydrophobic particles, macroscopic liquid droplets can become non-wetting liquid marbles that exhibit an array of fascinating solid-like properties. Specifically, the force required to uniaxially compress liquid marbles depends on their volume, but it is unclear if the particle coating plays a role. In contrast, the failure of marbles upon compression does depend on the particle coating, but the conditions for failure do not appear to change with marble volume.

Band Gap Engineering with Ultralarge Biaxial Strains in Suspended Monolayer MoS2.

We demonstrate the continuous and reversible tuning of the optical band gap of suspended monolayer MoS2 membranes by as much as 500 meV by applying very large biaxial strains. By using chemical vapor deposition (CVD) to grow crystals that are highly impermeable to gas, we are able to apply a pressure difference across suspended membranes to induce biaxial strains. We observe the effect of strain on the energy and intensity of the peaks in the photoluminescence (PL) spectrum and find a linear tuning rate of the optical band gap of 99 meV/%.