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Search Publications by: Andrew Slifka (Fed)

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Displaying 51 - 75 of 76

Stiffening of the Extrapulmonary Arteries in Chronic Hypoxic Pulmonary Hypertension

July 1, 2008
Author(s)
Elizabeth S. Drexler, J. E. Bischoff, Christopher N. McCowan, Andrew Slifka, Timothy P. Quinn, R Shandas, Dunbar Ivy, K. R. Stenmark
It is increasingly appreciated that changes in the compliance properties of large blood vessels are critical determinants of ventricular afterload and ultimately dysfunction. Little is known of the mechanical properties of large vessels in the setting of

A Uniaxial BioMEMS Device for Quantitative Force-Displacement Measurements

April 3, 2007
Author(s)
David Serrell, Tammy L. Oreskovic, Andrew Slifka, Roop L. Mahajan, Dudley Finch
There is a need for experimental techniques that allow the simultaneous imaging of cellular cystoskeletal components with quantitative force measurements on single cells. A bioMEMS device has been developed for the application of strain to a single cell

Strain-Induced Grain Growth during Rapid Thermal Cycling of Aluminum Interconnects

January 1, 2007
Author(s)
Robert Keller, Roy H. Geiss, Nicholas Barbosa, Andrew Slifka, David T. Read
We demonstrate by use of automated electron backscatter diffraction (EBSD) the rapid growth of grains in non-passivated, sputtered Al-1Si interconnects during 200 Hz thermal cycling induced by alternating electric current. Mean grain diameters were

Stress-strain behavior of rat pulmonary arteries

January 1, 2007
Author(s)
Elizabeth S. Drexler, J Wright, Andrew Slifka, Christopher N. McCowan, Dunbar Ivy, R Shandas
The stress-strain behavior of rat pulmonary arteries was studied using a bubble inflation technique. To obtain mechanical properties, an analytical method to evaluate the bubble test results was developed. A flat disk of rat pulmonary artery was

Electrical Methods for Mechanical Characterization of Interconnect Thin Films

September 1, 2005
Author(s)
Robert Keller, Cynthia A. Volkert, Roy H. Geiss, Andrew Slifka, David T. Read, Nicholas Barbosa, Reiner Monig
We describe the use of electrical methods for evaluating mechanical reliability and properties of patterned copper and aluminum interconnects on silicon substrates. The approach makes use of controlled Joule heating, which causes thermal strains in the

Implementation and Application of a Microstructurally Based Orthotropic Hyperelastic Model of Pulmonary Artery Mechanics under Normotensive and Hypertensive Conditions

August 1, 2005
Author(s)
Yang Zhang, Martin Dunn, Elizabeth S. Drexler, Christopher N. McCowan, Andrew Slifka, Dunbar Ivy, R Shandas
We implemented, validated, and applied a microstructurally based orthotropic hyperelastic constitutive model to simulate pulmonary artery mechanics under normotensive and hypoxic hypertensive conditions. The configuration of the model microstructure is a

Comparison of Strength Properties of Normotensive and Hypertensive Rat Pulmonary Arteries

October 1, 2004
Author(s)
Elizabeth S. Drexler, Christopher N. McCowan, J Wright, Andrew J. Slifka, Dunbar Ivy, Robin Shandas
A series of tests were conducted to quantify the difference in the mechanical properties of normo-and hypertensive pulmonary arteries. A bubble-test design was emplpoyed to measure the biaxial properties of a segment of artery. The test results compare the

Static and Quasi-static Calibration of Bio-MEMS Device

October 1, 2004
Author(s)
Andrew J. Slifka, Hrishikesh V. Panchawagh, Roop L. Mahajan, Dudley Finch, R. A. Rorrer
A bio-MEMS device which has been designed to stimulate cells by oscillatory actuation in the vertical direction has been calibrated. The displacement of this device was determined experimentally by a laser interferometer when actuated by a static voltage

An Experimental Method for Measuring Mechanical Properties of Rat Pulmonary Arteries Verified With Latex

June 1, 2003
Author(s)
Elizabeth S. Drexler, Andrew J. Slifka, J Wright, Christopher N. McCowan, Dudley Finch, Timothy P. Quinn, J D. McCloskey, Dunbar Ivy, Robin Shandas
A study of the biomechanics and hemodynamics of pulmonary hypertension is incomplete without including mechanical properties data comparing healthy and diseased arterial tissue. In the initial stabe of this study, Sprague-Dawley rats will be induced with

Thermal Evaluation of Scorched Graphite-Epoxy Panels by Infrared Scanning

March 1, 2003
Author(s)
Andrew J. Slifka, T Hall, E S. Boltz
A simple measurement system is described for evaluating damage to graphite-dpoxy panels, such as are used in high-performance aircraft. The system uses a heating laser and infrared imaging system to measure thermal performance. thermal conductivity or

Apparent Mobility of Interfaces in Integral Resistor Material

January 1, 2003
Author(s)
Andrew J. Slifka, John W. Drexler
Measurements were made on an integral resistor sample that showed apparent interfacial mobility. Initial measurements were made using infrared, optical, and scanning electron microscopies. Analysis of infrared microscopy measurements showed a broadening of

Thermomechanical Effects in Embedded Passive Materials

April 1, 2002
Author(s)
Andrew J. Slifka, Elizabeth S. Drexler
Thermomechanical fatigue was measured using electron-beam moire (EBM) and infrared (IR) microscopy. A specimen was made using FR-4 printed wiring board, (PWB), a silver-filled conductive adhesive, and a carbon-filled conductive paste. Both filled polymeric

Low Thermal Conductivity Vapor Deposited Zirconia Microstructures

April 1, 2001
Author(s)
D D. Hass, Andrew Slifka, H N. Wadley
Low thermal conductivity yttria stabilized zirconia (YSZ) coatings have been grown using a low vacuum (0.20 Torr) electron beam directed vapor deposition process. In this approach, a transsonic helium jet was used to entrain and transport an evaporated YSZ

The Effect of Thermal Shock on the Thermal Conductivity of a Functionally Graded Material

October 1, 1999
Author(s)
Andrew J. Slifka, M Packer, A Kumakawa, Bernard J. Filla, J M. Phelps, N Shimoda
We have measured the thermal conductivity of a ni20Cr / 8% yttria-partially-stabilized-zirconia functionally graded 1.1 mm thick coating on a substrate of 403 stainless steel. We measured thermal conductivity of the as-received coated specimen, then

Thermal Conductivity of Two Compositions of Yttria-Stabilized Zirconia

June 1, 1999
Author(s)
Andrew J. Slifka, Bernard J. Filla, Judith K. Stalick
The thermal conductivities of two different compositions of yttria-stabilized zirconia have been measured using an absolute, steady-state method. The measurements were made in a one-dised guarded-hot-plate apparatus from 130 C to 950 C. one material has a