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We report abundant nanodiamonds in sediments dating to 12.9 +/- 0.1 thousand calendar years before the present at multiple locations across North America. Selected area electron diffraction patterns reveal two diamond allotropes in this boundary layer but not above or below that interval. Cubic diamonds form under high temperature-pressure regimes, and(More)
An experimental and computational study of the bending response of steel sandwich panels with corrugated cores in both transverse and longitudinal loading orientations has been performed. Panel designs were chosen on the basis of failure mechanism maps, constructed using analytic models for failure initiation. The assessment affirms that the analytic models(More)
Residually compressed films and coatings are susceptible to buckle delamination. The buckles often have linear or telephone cord morphology. When the films are brittle, such buckles are susceptible to the formation of ridge cracks that extend along their length, terminating close to the propagating front. The ridge-cracked buckles are invariably(More)
Current understanding of lunar evolution is built on the Lunar Magma Ocean (LMO) hypothesis , which is based on the returned Apollo samples of ferroan anorthosites and the assumption that they are globally distributed. However, compositions of anorthositic clasts in lunar meteorites are inconsistent with a global LMO, and more consistent with crustal(More)
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