Sascha Hilgenfeldt

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Sound driven gas bubbles in water can emit light pulses. This phenomenon is called sonoluminescence ͑SL͒. Two different phases of single bubble SL have been proposed: diffusively stable and diffusively unstable SL. We present phase diagrams in the gas concentration versus forcing pressure state space and also in the ambient radius versus gas concentration(More)
The ability of collapsing (cavitating) bubbles to focus and concentrate energy, forces and stresses is at the root of phenomena such as cavitation damage, sonochemistry or sonoluminescence. In a biomedical context, ultrasound-driven microbubbles have been used to enhance contrast in ultrasonic images. The observation of bubble-enhanced(More)
The evolution of a foam is determined by drainage flow of the continuous (liquid) phase and coarsening (aging) of the dispersed phase (gas bubbles). Free-drainage experiments with slow- and fast-coarsening gases show markedly different dynamics and elucidate the importance of the coupling of the two effects. Strong coarsening leads to drainage times that(More)
In this paper we elaborate on the idea [Lohse et al., Phys. Rev. Lett. 78, 1359-1362 (1997)] that (single) sonoluminescing air bubbles rectify argon. The reason for the rectification is that nitrogen and oxygen dissociate and their reaction products dissolve in water. We give further experimental and theoretical evidence and extend the theory to other gas(More)
The diffusive coarsening of 2D soap froths is governed by von Neumann's law. A statistical version of this law for dry 3D foams has long been conjectured. A new derivation, based on a theorem by Minkowski, yields an explicit analytical von Neumann's law in 3D which is in very good agreement with detailed simulations and experiments. The average growth rate(More)
While solid mechanics has long dealt with traditional "hard" solids such as metals or amorphous materials, recent research in a variety of disciplines focuses on the understanding of Soft Matter-which turns out to be a harder problem in many respects. Soft matter is at the center of research in foams, suspensions, emulsions, slurries, and other composite(More)
Tiny collapsing bubbles can focus acoustic energy into bursts of visible light. Careful measurements of the emitted light reveal extraordinary conditions at the centre of the implosion of a single bubble, but not so extraordinary as to support fantastical claims. S onoluminescence is the astounding phenomenon that converts sound energy into visible light.(More)
Cells in the Drosophila retina have well-defined morphologies that are attained during tissue morphogenesis. We present a computer simulation of the epithelial tissue in which the global interfacial energy between cells is minimized. Experimental data for both normal cells and mutant cells either lacking or misexpressing the adhesion protein N-cadherin can(More)