Capillary Filling of Anodized Alumina Nanopore Arrays

The filling behavior of a room temperature solvent, perfluoromethylcyclohexane, in approximately 20 nm nanoporous alumina membranes was investigated in situ with small angle x-ray scattering. Adsorption in the pores was controlled reversibly by varying the chemical potential between the sample and a liquid reservoir via a thermal offset, $\Delta$T. The system exhibited a pronounced hysteretic capillary filling transition as liquid was condensed into the nanopores. These results are compared with Kelvin-Cohan theory, with a modified Derjaguin approximation, as well as with predictions by Cole and Saam.Comment: 4 pages, 3 figures, pre-proof

Capillary filling with wall corrugations] Capillary filling in microchannels with wall corrugations: A comparative study of the Concus-Finn criterion by continuum, kinetic and atomistic approaches

We study the impact of wall corrugations in microchannels on the process of capillary filling by means of three broadly used methods - Computational Fluid Dynamics (CFD), Lattice-Boltzmann Equations (LBE) and Molecular Dynamics (MD). The numerical results of these approaches are compared and tested against the Concus-Finn (CF) criterion, which predicts pinning of the contact line at rectangular ridges perpendicular to flow for contact angles theta > 45. While for theta = 30, theta = 40 (no flow) and theta = 60 (flow) all methods are found to produce data consistent with the CF criterion, at theta = 50 the numerical experiments provide different results. Whilst pinning of the liquid front is observed both in the LB and CFD simulations, MD simulations show that molecular fluctuations allow front propagation even above the critical value predicted by the deterministic CF criterion, thereby introducing a sensitivity to the obstacle heigth.Comment: 25 pages, 8 figures, Langmuir in pres

Effects of Limb Dominance and Sex on Upper Extremity Tissue Composition

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Influence of Testing Sequence on an Adult’s Ability to Achieve Maximal Aerobic and Anaerobic Power

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Effects of Limb Dominance and Sex on Upper Extremity Tissue Composition

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Taking Microarrays to the Field: Differential Hepatic Gene Expression of Caged Fathead Minnows from Nebraska Watersheds

This study aimed to evaluate the utility of microarrays as a biomonitoring tool in field studies. A 15,000-oligonucleotide microarray was used to measure the hepatic gene expression of fathead minnows (<i>Pimephales promelas</i>) caged in four Nebraska, USA watersheds - the Niobrara and Dismal Rivers (low-impact agricultural sites) and the Platte and Elkhorn Rivers (high-impact agricultural sites). Gene expression profiles were site specific and fish from the low- and high-impact sites aggregated into distinct groups. Over 1500 genes were differentially regulated between fish from the low- and high-impact sites. Many gene expression differences (1218) were also noted when the Platte and Elkhorn minnows were compared to one another and Platte fish experienced a higher degree of transcript alterations than Elkhorn fish. These findings indicate that there are differences between the low-impact and high-impact sites, as well as between the two high-impact sites. Historical water quality data support these results as only trace levels of agrichemicals have been detected at the low-impact sites, while substantial levels of agrichemicals have been reported at the high-impact sites with agrichemical loads at the Platte generally exceeding those at the Elkhorn. Overall, this study demonstrates that microarrays can be utilized to discriminate sites with different contaminant loads from one another

Adsorption Kinetics in Nanoscale Porous Coordination Polymers

Nanoscale porous coordination polymers were synthesized using simple wet chemical method. The effect of various polymer surfactants on colloidal stability and shape selectivity was investigated. Our results suggest that the nanoparticles exhibited significantly improved adsorption kinetics compared to bulk crystals due to decreased diffusion path lengths and preferred crystal plane interaction

Biomechanical analysis of four- versus six-screw constructs for short-segment pedicle screw and rod instrumentation of unstable thoracolumbar fractures

Conventionally, short-segment fusion involves instrumentation of one healthy vertebra above and below the injured vertebra, skipping the injured level. This short-segment construct places less surgical burden on the patient compared with long-segment constructs, but is less stable biomechanically, and thus has resulted in clinical failures. The addition of two screws placed in the fractured vertebral body represents an attempt to improve the construct stiffness without sacrificing the benefits of short-segment fusion. To determine the biomechanical differences between four- and six-screw short-segment constructs for the operative management of an unstable L1 fracture. Biomechanical study of instrumentation in vertebral body cadaveric models simulating an L1 axial load injury pattern. Thirteen intact spinal segments from T12 to L2 were prepared from fresh-frozen cadaver spines. An axial load fracture of at least 50% vertebral body height was produced at L1 and then instrumented with pedicle screws. Specimens were evaluated in terms of construct stiffness, motion, and rod strain. Two conditions were tested: a four-screw construct with no screws at the L1 fractured body (4S) and a six-screw construct with screws at all levels (6S). The two groups were compared statistically by paired Student t test. The mean stiffness in flexion-extension was increased 31% (p<.03) with the addition of the two pedicle screws in L1. Relative motion in terms of vertical and axial rotations was not significantly different between the two groups. The L1–L2 rod strain was significantly increased in the six-screw construct compared with the four-screw construct (p<.001). In a cadaveric L1 axial load fracture model, a six-screw construct with screws in the fractured level is more rigid than a four-screw construct that skips the injured vertebral body