MONDAY, October 12

KNI-MDL Monthly Seminar, 4:00 PM - 5:00 PM, 125 Steele

"Bio-Inspired Multi-Scale Energy-Dispersive Composites: Carbon
Nanotube-Architectures," Chiara Daraio, Assistant Professor of Aeronautics and Applied Physics, Caltech.

Abstract: We design bio-inspired periodic multilayer systems to create artificial hierarchical structures based on embedding vertically aligned carbon nanotubes (CNTs) in insulating and conductive Polydimethylsiloxane (PDMS) films. We test the bulk mechanical and viscoelastic properties under quasistatic and dynamic loading, and characterize in-situ the related structural and electronic properties. The resulting systems show interesting mechanical properties characterized by flexibility, lightweight, damage tolerance, strain localization, large recovery and energy absorption under different loading conditions. We propose a discrete model where the tubes are represented by a finite collection of bistable nonlinear springs showing excellent agreement with the experimental results. We study the continuum limit within the framework of Γ-convergence.

AND

"Fourier Transform soft X-ray (FTXR) Spectral Imager for Fingerprinting Bonding Structure in Minerals," Jaroslava Wilcox, Senior Engineer, Jet Propulsion Laboratory.

Abstract: The promise of adapting Fourier Transform (FT) techniques used in the IR into the soft X-ray region has been advocated in the past as a possible route to constructing a miniature spectral imager with spatial and spectral resolution similar to that attainable with a grating system using synchrotron radiation.  With a dramatically increased resolution over IR, core-level shift spectra of chemically and biologically significant elements could be mapped for each pixel of the image. We have initiated development of FTXR imager based on the use of a Mach-Zender type interferometer. This talk will describe the principle of operation of the instrument, with emphasis on development of beam-splitting mirrors - the enabling technology for the interferometer - in our laboratory at MDL, JPL.