Indirect measurement of interfacial melting from macroscopic ice observations.

Premelted water that is adsorbed to particle surfaces and confined to capillary regions remains in the liquid state well below the bulk melting temperature and can supply the segregated growth of ice lenses. Using macroscopic measurements of ice-lens initiation position in step-freezing experiments, we infer how the nanometer-scale thicknesses of premelted films depend on temperature depression below bulk melting. The interfacial interactions between ice, liquid, and soda-lime glass particles exhibit a power-law behavior that suggests premelting in our system is dominated by short-range electrostatic forces.

Hydrodynamic transitions with changing particle size that control ice lens growth.

Ice lenses are formed during soil freezing by the migration and solidification of premelted water that is adsorbed to ice-particle interfaces and confined to capillary regions. We develop a model of ice lens growth that clearly illustrates how the freezing rate dependence on particle size and soil microstructure changes in response to changes in the relative importance of permeable flow and thin-film flow in governing the water supply. The growth of an ice lens in fine-grained porous media is primarily constrained by low permeability in the unfrozen region.

Highly sensitive nanoscale spin-torque diode.

Highly sensitive microwave devices that are operational at room temperature are important for high-speed multiplex telecommunications. Quantum devices such as superconducting bolometers possess high performance but work only at low temperature. On the other hand, semiconductor devices, although enabling high-speed operation at room temperature, have poor signal-to-noise ratios.