Sat, 19 Jul 2008 11:18:18 BST CiteULike: weeks's methods http://www.citeulike.org/user/weeks/tag/methods CiteULike.org en-gb Copyright © 2004-2008 citeulike.org http://www.citeulike.org/user/weeks/article/2937514 <i>Langmuir, Vol. 22, No. 5. (28 February 2006), pp. 2005-2015.</i><br /><br />Abstract: Noise reduction, restoration, and segmentation methods are developed for the quantitative structural analysis in three dimensions of aggregated oil-in-water emulsion systems imaged by fluorescence confocal laser scanning microscopy. Mindful of typical industrial formulations, the methods are demonstrated for concentrated (30% volume fraction) and polydisperse emulsions. Following a regularized deconvolution step using an analytic optical transfer function and appropriate binary thresholding, novel application of the Euclidean distance map provides effective discrimination of closely clustered emulsion droplets with size variation over at least 1 order of magnitude. The a priori assumption of spherical nonintersecting objects provides crucial information to combat the ill-posed inverse problem presented by locating individual particles. Position coordinates and size estimates are recovered with sufficient precision to permit quantitative study of static geometrical features. In particular, aggregate morphology is characterized by a novel void distribution measure based on the generalized Apollonius problem. This is also compared with conventional Voronoi/Delauney analysis. Quantitative Imaging of Aggregated Emulsions R Penfold AD Watson AR Mackie DJ Hibberd doi:10.1021/la052719w Langmuir, Vol. 22, No. 5. (28 February 2006), pp. 2005-2015. 2008-06-27T15:07:13-00:00 2006 Langmuir 22 5 2005 2015 confocal emulsion imaging methods http://www.citeulike.org/user/weeks/article/2399521 <i>Applied Physics Letters, Vol. 89, No. 11. (2006)</i><br /><br />  Application of ferromagnetic nanowires to interfacial microrheology A Anguelouch RL Leheny DH Reich Applied Physics Letters, Vol. 89, No. 11. (2006) 2008-02-19T17:32:40-00:00 2006 Applied Physics Letters 89 11 AIP interface methods microrheology http://www.citeulike.org/user/weeks/article/2399493 <i>Advances in Colloid and Interface Science, Vol. 136, No. 1-2. (15 January 2008), pp. 65-92.</i><br /><br />Over the last decade, the light microscope has become increasingly useful as a quantitative tool for studying colloidal systems. The ability to obtain particle coordinates in bulk samples from micrographs is particularly appealing. In this paper we review and extend methods for optimal image formation of colloidal samples, which is vital for particle coordinates of the highest accuracy, and for extracting the most reliable coordinates from these images. We discuss in depth the accuracy of the coordinates, which is sensitive to the details of the colloidal system and the imaging system. Moreover, this accuracy can vary between particles, particularly in dense systems. We introduce a previously unreported error estimate and use it to develop an iterative method for finding particle coordinates. This individual-particle accuracy assessment also allows comparison between particle locations obtained from different experiments. Though aimed primarily at confocal microscopy studies of colloidal systems, the methods outlined here should transfer readily to many other feature extraction problems, especially where features may overlap one another. Confocal microscopy of colloidal particles: Towards reliable, optimum coordinates MC Jenkins SU Egelhaaf doi:10.1016/j.cis.2007.07.006 Advances in Colloid and Interface Science, Vol. 136, No. 1-2. (15 January 2008), pp. 65-92. 2008-02-19T17:20:12-00:00 2008 Advances in Colloid and Interface Science 136 1-2 65 92 confocal methods microscopy particle-tracking http://www.citeulike.org/user/weeks/article/983535 <i>Langmuir, Vol. 22, No. 24. (21 November 2006), pp. 9812-9815.</i><br /><br />Coating a close-packed fluorescent colloid monolayer with a nanometer-thick metal film followed by sonication in liquid produces modulated optical nanoprobes. The metal coating modulates the fluorescence as these structures rotate in suspension, enabling the use of these particles as probes to monitor both rotational and center-of-mass (translational) dynamics in complex environments. Here, we demonstrate methods to simultaneously measure two translational and two rotational degrees of freedom, with excellent agreement to theory. The capability to determine two angles of rotation opens several new avenues of future research. Single-Particle Colloid Tracking in Four Dimensions SM Anthony L Hong M Kim S Granick doi:10.1021/la062094h Langmuir, Vol. 22, No. 24. (21 November 2006), pp. 9812-9815. 2006-12-07T16:14:51-00:00 2006 Langmuir 22 24 9812 9815 brownian-motion methods particle-tracking rotation http://www.citeulike.org/user/weeks/article/822249 <i>Physical Review Letters, Vol. 85, No. 8. (2000), 1774.</i><br /><br />We study the dynamics of rigid spheres embedded in viscoelastic media and address two questions of importance to microrheology. First; we calculate the complete response to an external force of a single bead in a homogeneous elastic network viscously coupled to an incompressible fluid. From this response function we find the frequency range where the standard assumptions of microrheology are valid. Second; we study fluctuations when embedded spheres perturb the media around them and show that mutual fluctuations of two separated spheres provide a more accurate determination of the complex shear modulus than do the fluctuations of a single sphere. One- and Two-Particle Microrheology Alex Levine TC Lubensky doi:10.1103/PhysRevLett.85.1774 Physical Review Letters, Vol. 85, No. 8. (2000), 1774. 2006-08-30T16:26:55-00:00 2000 Physical Review Letters 85 8 1774 American Physical Society methods microrheology theory two-point http://www.citeulike.org/user/weeks/article/822252 <i>Physical Review E, Vol. 65, No. 5. (20 May 2002), 051505.</i><br /><br />Experiments investigating the local viscoelastic properties of a simple uncross-linked flexible polymer are performed on polyethylene oxide solutions in the semidilute regime using polystyrene beads of varying sizes and surface chemistry as probes. We measure the thermal motions of the beads to obtain the elastic and viscous moduli of our sample. Two different dynamic light scattering techniques; diffusing wave spectroscopy and quasielastic light scattering (QELS); are used to determine the dynamics of the probe particles. Diffusing wave spectroscopy probes the short time dynamics of the scatterers while QELS or single scattering measures the dynamics at larger times. This results in a larger frequency overlap of the data obtained from the microrheological techniques with the data obtained from the conventional bulk measurements. The moduli are estimated using a modified algebraic form of the generalized Stokes-Einstein equation. Comparison of microrheology with bulk measurements shows excellent similarity confirming the applicability of this method for simple; uncross-linked polymeric systems. Microrheology of polyethylene oxide using diffusing wave spectroscopy and single scattering Bivash Dasgupta Shang-You Tee John Crocker BJ Frisken DA Weitz doi:10.1103/PhysRevE.65.051505 Physical Review E, Vol. 65, No. 5. (20 May 2002), 051505. 2006-08-30T16:29:17-00:00 2002 Physical Review E 65 5 051505 American Physical Society dws methods microrheology http://www.citeulike.org/user/weeks/article/1689915 <i></i> Particle Tracking Using IDL: website Eric Weeks John Crocker 2007-09-24T16:32:57-00:00 methods particle-tracking web http://www.citeulike.org/user/weeks/article/300217 <i>J. Phys.: Condens. Matter, Vol. 15 (16 December 2003), pp. S257-S262.</i><br /><br />We introduce a new scheme for investigating temporally heterogeneous dynamics, which is termed time-resolved correlation (TRC). TRC is applied to data obtained by diffusing wave spectroscopy probing the slow dynamics of a strongly aggregated colloidal gel. Other examples of TRC data, collected for different jammed materials in single and multiple scattering, are provided to demonstrate the wide range of applicability of this method. In all cases we find evidence that the slow dynamics results from a series of discrete steps rather than from a continuous motion, suggesting temporal heterogeneities to be a general feature of slow dynamics in jammed systems. Time-resolved correlation: a new tool for studying temporally heterogeneous dynamics Luca Cipelletti H Bissig V Trappe P Ballesta S Mazoyer J. Phys.: Condens. Matter, Vol. 15 (16 December 2003), pp. S257-S262. 2005-08-22T03:28:42-00:00 2003 J. Phys.: Condens. Matter 15 S257 S262 aging dyn-het methods trc http://www.citeulike.org/user/weeks/article/1201312 <i>Optics Express, Vol. 15, No. 4. (19 February 2007), pp. 1505-1512.</i><br /><br />Holographic optical trapping uses forces exerted by computer-generated holograms to organize microscopic materials into three-dimensional structures. In a complementary manner, holographic video microscopy uses real-time recordings of in-line holograms to create time-resolved volumetric images of three-dimensional microstructures. The combination is exceptionally effective for organizing, inspecting and analyzing soft-matter systems. Holographic microscopy of holographically trapped three-dimensional structures Sang-Hyuk Lee David Grier Optics Express, Vol. 15, No. 4. (19 February 2007), pp. 1505-1512. 2007-04-01T02:58:44-00:00 2007 Optics Express 15 4 1505 1512 journal-club laser-tweezer methods http://www.citeulike.org/user/weeks/article/1304903 <i>Colloids and Surfaces, Vol. 17, No. 1. (January 1986), pp. 67-78.</i><br /><br />A single-stage method is described for preparing monodisperse poly(methyl methacrylate) latices stabilised by poly(12-hydroxy-stearic acid) in hydrocarbon media. By variation of solvency conditions, it was possible to obtain a variation in particle size. At high monomer concentrations, a range of particle diameters between 178 nm and 2.6 [mu]m was obtained with a small coefficient of variation on the number average size. At low monomer concentrations, stable latices were obtained with diameters of ~ 80 nm. Some suggestions are made for the mechanism of particle formation and growth in non-aqueous latices. The preparation of poly(methyl methacrylate) latices in non-aqueous media L Antl JW Goodwin RD Hill RH Ottewill SM Owens S Papworth JA Waters doi:10.1016/0166-6622(86)80187-1 Colloids and Surfaces, Vol. 17, No. 1. (January 1986), pp. 67-78. 2007-05-18T07:18:28-00:00 1986 Colloids and Surfaces 17 1 67 78 colloids methods pmma synthesis http://www.citeulike.org/user/weeks/article/1304905 <i>Journal of Colloid and Interface Science, Vol. 179, No. 1. (15 April 1996), pp. 298-310.</i><br /><br />We describe a set of image processing algorithms for extracting quantitative data from digitized video microscope images of colloidal suspensions. In a typical application, these direct imaging techniques can locate submicrometer spheres to within 10 nm in the focal plane and 150 nm in depth. Combining information from a sequence of video images into single-particle trajectories makes possible measurements of quantities of fundamental and practical interest such as diffusion coefficients and pair-wise interaction potentials. The measurements we describe in detail combine the outstanding resolution of digital imaging with video-synchronized optical trapping to obtain highly accurate and reproducible results very rapidly. Methods of Digital Video Microscopy for Colloidal Studies John Crocker David Grier doi:10.1006/jcis.1996.0217 Journal of Colloid and Interface Science, Vol. 179, No. 1. (15 April 1996), pp. 298-310. 2007-05-18T07:19:49-00:00 1996 Journal of Colloid and Interface Science 179 1 298 310 methods microscopy particle-tracking http://www.citeulike.org/user/weeks/article/1379322 <i>Applied Optics, Vol. 40, No. 24. (2001), pp. 4152-4159.</i><br /><br />Confocal microscopy is used in the study of colloidal gels, glasses, and binary fluids. We measure the three-dimensional positions of colloidal particles with a precision of approximately 50 nm (a small fraction of each particle s radius) and with a time resolution sufficient for tracking the thermal motions of several thousand particles at once. This information allows us to characterize the structure and the dynamics of these materials in qualitatively new ways, for example, by quantifying the topology of chains and clusters of particles as well as by measuring the spatial correlations between particles with high mobilities. We describe our experimental technique and describe measurements that complement the results of light scattering. Three-Dimensional Confocal Microscopy of Colloids AD Dinsmore ER Weeks V Prasad AC Levitt DA Weitz Applied Optics, Vol. 40, No. 24. (2001), pp. 4152-4159. 2007-06-11T21:35:48-00:00 2001 Applied Optics 40 24 4152 4159 colloidal-gel colloids confocal glass methods pmma http://www.citeulike.org/user/weeks/article/822942 <i>Physical Review Letters, Vol. 85, No. 4. (24 July 2000), pp. 888-891.</i><br /><br />We demonstrate a novel method for measuring the microrheology of soft viscoelastic media; based on cross correlating the thermal motion of pairs of embedded tracer particles. The method does not depend on the exact nature of the coupling between the tracers and the medium; and yields accurate rheological data for highly inhomogeneous materials. We demonstrate the accuracy of this method with a guar solution; for which other microscopic methods fail due to the polymer's mesoscopic inhomogeneity. Measurements in an F-actin solution suggest conventional microrheology measurements may not reflect the true bulk behavior. Two-Point Microrheology of Inhomogeneous Soft Materials John Crocker MT Valentine Eric Weeks T Gisler PD Kaplan AG Yodh DA Weitz doi:10.1103/PhysRevLett.85.888 Physical Review Letters, Vol. 85, No. 4. (24 July 2000), pp. 888-891. 2006-08-31T12:33:47-00:00 2000 Physical Review Letters 85 4 888 891 American Physical Society methods microrheology two-point