We describe a microrheological strategy that enables sensitive surface shear rheology measurements of surfactant-laden interfaces, with the capacity to simultaneously visualize deforming interfaces. This technique utilizes a ferromagnetic microbutton probe pinned to a fluid-fluid interface, and actively torqued or forced with externally controlled electromagnets. Various modes of operation are possible: Smallamplitude oscillatory rotations, which provide frequency-dependent viscoelastic shear moduli; controlled torque (analogous to fixing shear stress); controlled rotation rate (analogous to fixing strain rate); and imposed force (analogous to active, translational microrheology). The circular shape of the probe ensures pure shear strains (when driven to rotate). We describe the experimental apparatus, its measurement limits and sources of error. We then highlight its versatility and capabilities with measurements on a variety of qualitatively distinct systems, including purely viscous monolayers, block-copolymer interfaces, aging and evolving interfaces, colloidal monolayers, and bulk rheometry of Newtonian and viscoelastic materials, with sample volumes as small as 2 ll. V

A power law model for cavitation erosion is proposed herein that represents volume loss as the creation and subsequent enlargement of hemispherical pits in the surface of the solid. The cumulative volume loss (CVL) of a material is expressed as an Arrhenius term, containing the energy of pit growth, E pg , multiplied by a power law function with the pit radius growth rate, k, as a prefactor and a time exponent, n. The model is verified through fitting of experimental cavitation erosion data for commercially-available aluminum, copper, and zinc substrates, as well as fitting selected data from the International Cavitation Erosion Test and through comparison with other cumulative volume loss models.

The production of functionalized clinoatacamite (Cu 2 (OH) 3 Cl) nanoparticles from Reactive Cavitation Erosion (RCE) of copper in 1 M aqueous guanidine hydrochloride (GHCl) solution was investigated for applications as potential quantum magnet materials. As-synthesized nanomaterial was characterized by Diffuse-Reflectance Infrared Fourier-Transform Spectroscopy (DRIFTS), XRD, and TEM. These analyses were compared to nanoparticles produced from RCE of Cu in KCl and RCE of Cu in GHCl in oxygen-depleted (Ar) and oxygen-rich (compressed air, CA) solutions to identify possible reaction pathways.