Sat, 26 Jul 2008 06:26:53 BST CiteULike: dchen's Lohse http://www.citeulike.org/user/dchen/author/Lohse CiteULike.org en-gb Copyright © 2004-2008 citeulike.org http://www.citeulike.org/user/dchen/article/2753716 <i>Physical Review Letters, Vol. 98, No. 20. (2007)</i><br /><br />Shock wave induced cavitation experiments and atomic force microscopy measurements of flat polyamide and hydrophobized silicon surfaces immersed in water are performed. It is shown that surface nanobubbles, present on these surfaces, do not act as nucleation sites for cavitation bubbles, in contrast to the expectation. This implies that surface nanobubbles are not just stable under ambient conditions but also under enormous reduction of the liquid pressure down to -6 MPa. We denote this feature as superstability. Superstability of Surface Nanobubbles Bram Borkent Stephan Dammer Holger Schönherr Julius Vancso Detlef Lohse doi:10.1103/PhysRevLett.98.204502 Physical Review Letters, Vol. 98, No. 20. (2007) 2008-05-04T16:08:51-00:00 2007 Physical Review Letters 98 20 APS 2007 bubbles focus material nano http://www.citeulike.org/user/dchen/article/2553084 <i>Physical Review Letters, Vol. 99, No. 1. (2007)</i><br /><br />A steel ball impacting on a bed of very loose, fine sand results in a surprisingly vigorous jet which shoots up from the surface of the sand [D. Lohse et al., Phys. Rev. Lett. 93, 198003 (2004)]. When the ambient pressure p is reduced, the jet is found to be less vigorous [R. Royer et al., Nature Phys. 1, 164 (2005)]. In this Letter we show that p also affects the rate of penetration of the ball: Higher pressure increases the rate of penetration, which makes the cavity created by the ball close deeper into the sand bed, where the hydrostatic pressure is stronger, thereby producing a more energetic collapse and jetting. The origin of the deeper penetration under normal ambient pressure is found to lie in the extra sand fluidization caused by the air flow induced by the falling ball. Role of Air in Granular Jet Formation Gabriel Caballero Raymond Bergmann Devaraj van der Meer Andrea Prosperetti Detlef Lohse doi:10.1103/PhysRevLett.99.018001 Physical Review Letters, Vol. 99, No. 1. (2007) 2008-03-18T22:10:03-00:00 2007 Physical Review Letters 99 1 APS 2007 flow grains