Steven J Eppell

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The three-dimensional tertiary structure of human von Willebrand Factor (vWF) on a hydrophobic surface under aqueous conditions and different shear stress regimes was studied by atomic force microscopy (AFM). vWF was imaged by AFM at molecular level resolution under negligible shear stress, under a local applied shear force (7.4 to 19 nN) using the AFM(More)
Collagen, an essential building block of connective tissues, possesses useful mechanical properties due to its hierarchical structure. However, little is known about the mechanical properties of collagen fibril, an intermediate structure between the collagen molecule and connective tissue. Here, we report the results of systematic molecular dynamics(More)
We present a technique for reconstructing biomolecular structures from scanning force microscope data. The technique works by iteratively refining model molecules by comparison of simulated and experimental images. It can remove instrument artifacts to yield accurate dimensional measurements from tip-broadened data. The result of the reconstruction is a(More)
We obtain analytical expressions for electrostatic forces between an atomic force microscope tip and a sample immersed in an electrolyte. These simple expressions relate force to tip-sample separation explicitly incorporating tip size, solvent ion size, and solvent ion concentration. If the ions are much smaller than the tip-sample gap, the force decays(More)
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