Bruce J Ackerson

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Direct imaging of settling, non-Brownian, hard sphere, particles allows measurement of particle occupancy statistics as a function of time and sampling volume dimension. Initially random relative particle number fluctuations, <N2-<N>(2)>/<N> = 1, become suppressed, anisotropic, and <N> dependent. Fitting to a simple Gaussian pair correlation model suggests(More)
Multiple light scattering can be suppressed by slightly tilting two single-mode fibers viewing the same sample volume. The cross-correlation function of the two signals shows more or less contributions from single scattering, depending on the tilt angle. We show experimental results for polystyrene spheres at a scattering angle of 90 degrees . The measured(More)
This feature article reviews the thermal dissipation of nanoscopic gold under radiofrequency (RF) irradiation. It also presents previously unpublished data addressing obscure aspects of this phenomenon. While applications in biology motivated initial investigation of RF heating of gold nanoparticles, recent controversy concerning whether thermal effects can(More)
Studies by dynamic and total intensity light scattering, ultracentrifugation, electron microscopy, and chemical crosslinking on solutions of the pig heart mitochondrial enzymes, malate dehydrogenase and citrate synthase (separately and together) demonstrate that polyethylene glycol induces very large homoassociations of each enzyme, and still larger(More)
The Brownian motion of molecules at thermal equilibrium usually has a finite correlation time and will eventually be randomized after a long delay time, so that their displacement follows the Gaussian statistics. This is true even when the molecules have experienced a complex environment with a finite correlation time. Here, we report that the lateral(More)
We examine crystallization by settling for two different model hard-sphere suspensions. Sedimentation velocities, internal shock velocities, and crystal growth velocities are measured. Dynamic light scattering experiments measure volume fraction profiles in fluid phases, while Bragg scattering experiments determine volume fraction profiles in crystal(More)
This work delineates the mechanism by which directional nanowire growth occurs in the directed electrochemical nanowire assembly (DENA) technique for growing nanowires on micro-electrode arrays. Indium, polythiophene, and polypyrrole nanowires are the subjects of this study. This technique allows the user to specify the growth path without the use of a(More)
Two single-mode fibers collect light with the same scattered wave vector from two spatially separated regions in a sample. These regions are illuminated by a single coherent laser beam, so that the collected signals interfere when combined by means of a fiber-optic coupler, before they are directed to a photomultiplier tube. The fibers and the coupler are(More)
We report band formation and other pattern formation for a settling suspension of uniform non-Brownian particles in a completely filled horizontal rotating cylinder. The system shows a series of sharp pattern changes that are mapped out as a function of the rotation period and suspension viscosity. The experiment suggests that a large number of patterns and(More)
Frost injury patterns are commonly observed on the warm-season turfgrass species bermudagrass (Cynodon species Rich.), zoysiagrass (Zoysia species Willd.), and buffalograss [Bouteloua dactyloides (Nutt.) J.T. Columbus] in cool-temperate and subtropical zones. Qualitative observations of these injury patterns are presented and discussed. A model for the(More)