Sat, 26 Jul 2008 06:17:09 BST CiteULike: dchen's Zhu http://www.citeulike.org/user/dchen/author/Zhu CiteULike.org en-gb Copyright © 2004-2008 citeulike.org http://www.citeulike.org/user/dchen/article/2551985 <i>Physical Review Letters, Vol. 96, No. 7. (2006)</i><br /><br />We report a size dependence of Young's modulus in [0001] oriented ZnO nanowires (NWs) with diameters ranging from 17 to 550 nm for the first time. The measured modulus for NWs with diameters smaller than about 120 nm is increasing dramatically with the decreasing diameters, and is significantly higher than that of the larger ones whose modulus tends to that of bulk ZnO. A core-shell composite NW model in terms of the surface stiffening effect correlated with significant bond length contractions occurred near the 100 free surfaces (which extend several layers deep into the bulk and fade off slowly) is proposed to explore the origin of the size dependence, and present experimental result is well explained. Furthermore, it is possible to estimate the size-related elastic properties of GaN nanotubes and relative nanostructures by using this model. Size Dependence of Young's Modulus in ZnO Nanowires CQ Chen Y Shi YS Zhang J Zhu YJ Yan doi:10.1103/PhysRevLett.96.075505 Physical Review Letters, Vol. 96, No. 7. (2006) 2008-03-18T16:20:22-00:00 2006 Physical Review Letters 96 7 APS atlanta gt modulus nano people http://www.citeulike.org/user/dchen/article/2751731 <i>Physical Review Letters, Vol. 99, No. 16. (2007)</i><br /><br />The dynamic process of intense 50 fs laser ablation of aluminum is investigated by ultrafast time-resolved microscopy. A stripe pattern preceding phase explosion is clearly seen in the shadowgraph of 1 ns time delay. Intermittent material ejections are observed within the ejected plume after 2.5 and 7 ns time delay, respectively, which may be attributed to the material response to the generation of an extremely strong thermoelastic wave. Similar processes are also recorded in the ablation of silicon and glass samples, except for the glass samples, the intermittent material ejections are not found. Time-Resolved Shadowgraphs of Material Ejection in Intense Femtosecond Laser Ablation of Aluminum Nan Zhang Xiaonong Zhu Jianjun Yang Xiaolei Wang Mingwei Wang doi:10.1103/PhysRevLett.99.167602 Physical Review Letters, Vol. 99, No. 16. (2007) 2008-05-03T23:46:49-00:00 2007 Physical Review Letters 99 16 APS 2007 focus material nano people http://www.citeulike.org/user/dchen/article/1449898 <i>Physical Review E, Vol. 65, No. 4. (April 2002), 041405.</i><br /><br />Measurements of the low-shear viscosity η o with a Zimm-Crothers viscometer for dispersions of colloidal hard spheres are reported as a function of volume fraction φ up to 0.56. Nonequilibrium theories based on solutions to the two-particle Smoluchoski equation or ideal mode coupling approximations do not capture the divergence. However; the nonhydrodynamic contribution to the relative viscosity Δη o is correlated over a wide range of volume fractions by the Doolittle and Adam-Gibbs equations; indicating an exponential divergence at φ m =0.625±0.015. The data extend the previously proposed master curve; providing a test for improved theories for the many-body thermodynamic and hydrodynamic interactions that determine the viscosity of hard-sphere dispersions. Nature of the divergence in low shear viscosity of colloidal hard-sphere dispersions Zhengdong Cheng Jixiang Zhu Paul Chaikin See-Eng Phan William Russel doi:10.1103/PhysRevE.65.041405 Physical Review E, Vol. 65, No. 4. (April 2002), 041405. 2007-07-11T20:42:14-00:00 2002 Physical Review E 65 4 041405 American Physical Society colloids density viscosity