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Biomedical Engineering and Bioengineering Commons

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Full-Text Articles in Biomedical Engineering and Bioengineering

Elastic Waves Push Organic Fluids From Reservoir Rock, Igor A. Beresnev, R. Dennis Vigil, Wenqing Li, Wayne D. Pennington, Roger M. Turpening, Pavel P. Iassonov, Robert P. Ewing Jul 2005

Elastic Waves Push Organic Fluids From Reservoir Rock, Igor A. Beresnev, R. Dennis Vigil, Wenqing Li, Wayne D. Pennington, Roger M. Turpening, Pavel P. Iassonov, Robert P. Ewing

Chemical and Biological Engineering Publications

Elastic waves have been observed to increase productivity of oil wells, although the reason for the vibratory mobilization of the residual organic fluids has remained unclear. Residual oil is entrapped as ganglia in pore constrictions because of resisting capillary forces. An external pressure gradient exceeding an ‘‘unplugging’’ threshold is needed to carry the ganglia through. The vibrations help overcome this resistance by adding an oscillatory inertial forcing to the external gradient; when the vibratory forcing acts along the gradient and the threshold is exceeded, instant ‘‘unplugging’’ occurs. The mobilization effect is proportional to the amplitude and inversely proportional to the ...


Nanoscale Morphology Of Polyanhydride Copolymers, Matthew J. Kipper, Sheng-Shu Hou, Soenke Seifert, Papannan Thiyagarajan, Klaus Schmidt-Rohr, Balaji Narasimhan Jan 2005

Nanoscale Morphology Of Polyanhydride Copolymers, Matthew J. Kipper, Sheng-Shu Hou, Soenke Seifert, Papannan Thiyagarajan, Klaus Schmidt-Rohr, Balaji Narasimhan

Chemical and Biological Engineering Publications

The microphase separation in polyanhydride random copolymers composed of 1,6-bis(p-carboxyphenoxy)hexane and sebacic acid is described. Though the copolymers are random, the monomers are sufficiently long and the segment-segment interaction parameter is sufficiently high to promote microphase separation when the copolymer is rich in one component. Solid-state NMR spin diffusion experiments and synchrotron small-angle X-ray scattering are used to discern the length scales of the microphase separation. Both techniques reveal a nanostructure with domain sizes less than 25 Ã…. This nanostructure is compared to approximate calculations of chain dimensions based on a random coil model and discussed in ...


Construction Of A Tethered Poly(Ethylene Glycol) Surface Gradient For Studies Of Cell Adhesion Kinetics, K. Mougin, A. S. Ham, M. B. Lawrence, E. J. Fernandez, Andrew C. Hillier Jan 2005

Construction Of A Tethered Poly(Ethylene Glycol) Surface Gradient For Studies Of Cell Adhesion Kinetics, K. Mougin, A. S. Ham, M. B. Lawrence, E. J. Fernandez, Andrew C. Hillier

Chemical and Biological Engineering Publications

Surface gradients can be used to perform a wide range of functions and represent a novel experimental platform for combinatorial discovery and analysis. In this work, a gradient in the coverage of a surface-immobilized poly(ethylene glycol) (PEG) layer is constructed to interrogate cell adhesion on a solid surface. Variation of surface coverage is achieved by controlled transport of a reactive PEG precursor from a point source through a hydrated gel. Immobilization of PEG is achieved by covalent attachment of the PEG molecule via direct coupling chemistry to a cystamine self-assembled monolayer on gold. This represents a simple method for ...


Surfactant Properties Of Low Molecular Weight Phospholipids, Punjaporn Weschayanwiwat, John F. Scamehorn, Peter J. Reilly Jan 2005

Surfactant Properties Of Low Molecular Weight Phospholipids, Punjaporn Weschayanwiwat, John F. Scamehorn, Peter J. Reilly

Chemical and Biological Engineering Publications

Surface tensions, critical micelle concentrations (CMCs), contact angles on hydrophobic polyethylene, and foaming characteristics of phosphatidic acids, phosphatidylcholines, phosphatidylethanolamines, and phosphatidylglycerols were measured to determine their suitability as substitutes for traditional surfactants. These phospholipids have fatty acid chains of 5 to 12 carbon atoms, a range over which they are soluble at room temperature. Their surface tensions decrease with increasing concentrations until their CMCs are reached, above which their plateau surface tensions are as low as 21 mN/m, indicating excellent surface activities. In general, plateau surface tensions decrease with increasing chain length within each phospholipid type. The classical relationship ...