CiteULike: dchen's experiment http://www.citeulike.org/user/dchen/tag/experiment CiteULike.org en-gb Copyright © 2004-2008 citeulike.org http://www.citeulike.org/user/dchen/article/1699637 <i>Science, Vol. 290, No. 5496. (24 November 2000), pp. 1536-1540.</i><br /><br />10.1126/science.290.5496.1536 From Micro- to Nanofabrication with Soft Materials Stephen Quake Axel Scherer doi:10.1126/science.290.5496.1536 Science, Vol. 290, No. 5496. (24 November 2000), pp. 1536-1540. 2007-09-27T08:45:33-00:00 Science 290 5496 1536 1540 experiment nano qualifier review technique http://www.citeulike.org/user/dchen/article/2582925 <i>Journal of Physics: Condensed Matter, Vol. 17, No. 24. (2005), pp. S2533-S2548.</i><br /><br />We measure the flow of granular materials inside a quasi-two-dimensional silo as it drains and compare the data with some existing models. The particles inside the silo are imaged and tracked with unprecedented resolution in both space and time to obtain their velocity and diffusion properties. The data obtained by varying the orifice width and the hopper angle allow us to thoroughly test models of gravity driven flows inside these geometries. All of our measured velocity profiles are smooth and free of the shock-like discontinuities ('rupture zones') predicted by critical state soil mechanics. On the other hand, we find that the simple kinematic model accurately captures the mean velocity profile near the orifice, although it fails to describe the rapid transition to plug flow far away from the orifice. The measured diffusion length b, the only free parameter in the model, is not constant as usually assumed, but increases with both the height above the orifice and the angle of the hopper. We discuss improvements to the model to account for the differences. From our data, we also directly measure the diffusion of the particles and find it to be significantly less than predicted by the void model, which provides the classical microscopic derivation of the kinematic model in terms of diffusing voids in the packing. However, the experimental data are consistent with the recently proposed spot model, based on a simple mechanism for cooperative diffusion. Finally, we discuss the flow rate as a function of the orifice width and hopper angles. We find that the flow rate scales with the orifice size to the power of 1.5, consistent with dimensional analysis. Interestingly, the flow rate increases when the funnel angle is increased. Velocity profile of granular flows inside silos and hoppers Jaehyuk Choi Arshad Kudrolli Martin Bazant doi:10.1088/0953-8984/17/24/011 Journal of Physics: Condensed Matter, Vol. 17, No. 24. (2005), pp. S2533-S2548. 2008-03-24T22:32:04-00:00 Journal of Physics: Condensed Matter 17 24 S2533 S2548 experiment grains qualifer http://www.citeulike.org/user/dchen/article/2563129 <i>Physical Review Letters, Vol. 98, No. 2. (2007)</i><br /><br />The results of an experimental investigation into the effects of particle shape on the stress dip formed under a 2D sandpile is reported. We find good agreement with previous results of a small dip for mixtures of disks poured from a localized source. The new finding is that the dip is significantly enhanced when elliptical particles are used. We attribute the amplification of the effect to orientational ordering induced by the shape of the grains which removes the degeneracy of circular particles. Effect of Particle Shape on the Stress Dip Under a Sandpile I Zuriguel T Mullin JM Rotter doi:10.1103/PhysRevLett.98.028001 Physical Review Letters, Vol. 98, No. 2. (2007) 2008-03-19T17:13:57-00:00 Physical Review Letters 98 2 APS 2007 experiment force grains http://www.citeulike.org/user/dchen/article/2563095 <i>Physical Review Letters, Vol. 98, No. 4. (2007)</i><br /><br />X-ray photon-correlation spectroscopy is used to measure the dynamic structure factor f(q,) of gold particles moving on the surface of thin polymer films. Above the glass transition of the polymer the peculiar form f(q,)~exp[-()] is found with 0.7<<1.5, depending on sample age and temperature. The relaxation rates scale linearly with q, excluding a simple Brownian diffusive motion. This type of behavior, already observed in aging bulk soft matter systems, is explained by a power law distribution of particle velocities due to ballistic motion. Two-Dimensional Dynamics of Metal Nanoparticles on the Surface of Thin Polymer Films Studied with Coherent X Rays S Streit C Gutt V Chamard A Robert M Sprung H Sternemann M Tolan doi:10.1103/PhysRevLett.98.047801 Physical Review Letters, Vol. 98, No. 4. (2007) 2008-03-19T17:03:19-00:00 Physical Review Letters 98 4 APS 2007 diffusion experiment film nano polymer http://www.citeulike.org/user/dchen/article/1988262 <i>Physical Review Letters, Vol. 98, No. 10. (2007)</i><br /><br />We provide a direct experimental test of the fluctuation-dissipation theorem (FDT) in an aging colloidal glass. The use of combined active and passive microrheology allows us to independently measure both the correlation and response functions in this nonequilibrium situation. Contrary to previous reports, we find no deviations from the FDT over several decades in frequency (1 Hz–10 kHz) and for all aging times. In addition, we find two distinct viscoelastic contributions in the aging glass, including a nearly elastic response at low frequencies that grows during aging. Fluctuation-Dissipation Theorem in an Aging Colloidal Glass Sara Farouji Daisuke Mizuno Maryam Atakhorrami Fred Mackintosh Christoph Schmidt Erika Eiser Gerard Wegdam Daniel Bonn doi:10.1103/PhysRevLett.98.108302 Physical Review Letters, Vol. 98, No. 10. (2007) 2007-11-26T20:20:36-00:00 Physical Review Letters 98 10 APS 2007 aging colloids experiment glass theory http://www.citeulike.org/user/dchen/article/2553406 <i>Physical Review Letters, Vol. 98, No. 15. (2007)</i><br /><br />We show that under appropriate conditions, mixtures of oil, water, and nanoparticles form thermodynamically stable oil-in-water emulsions with monodisperse droplet diameters in the range of 30–150 nm. This observation challenges current wisdom that so-called Pickering emulsions are at most metastable and points to a new class of mesoscopic equilibrium structures. Thermodynamic stability is demonstrated by the spontaneous evolution of binary droplet mixtures towards one intermediate size distribution. Equilibrium interfacial curvature due to an asymmetric charge distribution induced by adsorbed colloids explains the growth of emulsion droplets upon salt addition. Moreover, the existence of a minimal radius of curvature with a concomitant expulsion of excess oil is in close analogy with microemulsions. Thermodynamically Stable Pickering Emulsions S Sacanna WK Kegel AP Philipse doi:10.1103/PhysRevLett.98.158301 Physical Review Letters, Vol. 98, No. 15. (2007) 2008-03-19T01:12:04-00:00 Physical Review Letters 98 15 APS 2007 emulsion experiment technique http://www.citeulike.org/user/dchen/article/1304855 <i>Physical Review Letters, Vol. 81, No. 13. (1998), 2727.</i><br /><br />We directly measure the equilibrium length scale of dynamic heterogeneities close to the glass transition by means of a new multidimensional NMR experiment. The spatial information is gained from a proton spin diffusion experiment combined with two 2D 13 C exchange sequences via appropriate back and forth transfer of magnetization between 13 C and 1 H spins. For poly(vinyl acetate) at 10 K above the glass transition we detected a length scale of 3±1 nm. Length Scale of Dynamic Heterogeneities at the Glass Transition Determined by Multidimensional Nuclear Magnetic Resonance U Tracht M Wilhelm A Heuer H Feng K Schmidt-Rohr HW Spiess doi:10.1103/PhysRevLett.81.2727 Physical Review Letters, Vol. 81, No. 13. (1998), 2727. 2007-05-18T06:44:44-00:00 Physical Review Letters 81 13 2727 American Physical Society experiment heterogeneity mnmr http://www.citeulike.org/user/dchen/article/2453868 <i>The Journal of Chemical Physics, Vol. 115, No. 6. (2001), pp. 2676-2680.</i><br /><br />  Observation of heterogeneity in the nanosecond dynamics of a liquid Min Yang Ranko Richert The Journal of Chemical Physics, Vol. 115, No. 6. (2001), pp. 2676-2680. 2008-03-01T22:00:29-00:00 The Journal of Chemical Physics 115 6 2676 2680 AIP experiment heterogeneity http://www.citeulike.org/user/dchen/article/2453702 <i>Science</i> Direct Observation of Dynamical Heterogeneities in Colloidal Hard-Sphere Suspensions Willem Kegel Alfons van Blaaderen Science 2008-03-01T20:33:48-00:00 Science experiment heterogeneity