Stress-strain measurements and ultrasound propagation experiments in glass bead packs have been simultaneously conducted to characterize the stress-induced anisotropy under uniaxial loading. These measurements realized, respectively, with finite and incremental deformations of the granular assembly, are analyzed within the framework of the effective-medium theory based on the Hertz-Mindlin cont...

This article describes a nanomanipulation technique that makes it possible to mechanically and quantitatively stretch and supercoil a single linear DNA molecule. We show how this technique can be extended to the study of protein–DNA interactions that lead to DNA untwisting, particularly to the study of promoter unwinding by RNA polymerase during the initiation of transcription. In our system, a...

Despite extensive efforts, a definitive picture of the glass transition of ultra-thin polymer films has yet to emerge. The effect of film thickness h on the glass transition temperature T(g) has been widely examined, but this characterization does not account for the fragility of glass-formation, which quantifies how rapidly relaxation times vary with temperature T. Accordingly, we simulate sup...

An experimental study of shock wave profiles in particulate composites of various compositions is undertaken to determine how shock width and rise times depend on the mean particulate size. The composites under examination serve as a model for concrete or polymer bonded explosives, based upon the impedance mismatch between the relatively stiff particulates and compliant matrix. Polymethyl Metha...

A generic method is described for forming surface-bound structures that incorporate protein receptors in a membrane-like environment. Silane reagents (octadecyltrichlorosilane and dimethyloctadecylchlorosilane) were used to produce primed substrates bearing full and partial monolayers, respectively. Biomembranes were formed by dialysis of detergent-solubilized membranes in the presence of two d...

A reconstituted system for examining directed organelle movements along purified microtubules has been developed. Axoplasm from the squid giant axon was separated into soluble supernatant and organelle-enriched fractions. Movement of axoplasmic organelles along MAP-free microtubules occurred consistently only after addition of axoplasmic supernatant and ATP. The velocity of such organelle movem...

Excavations in the Roman villa of Aiano yielded twenty glass beads, a pendant, and glass-recycling furnace, originally interpreted as bead workshop. This article re-assesses evidence making light new data obtained thanks to recent progress archaeological studies. A detailed study typology, technology, chemical composition beads clearly excludes local production. Instead, two different forming t...