– The dynamics of many continuous degrees of freedom interacting via a random potential and subject to a global spherical constraint is investigated. The model is a prototype mean-field model for structural glasses near the glass transition. In the high temperature phase the model is described by equations similar to those of the Schematic Mode Coupling Theory for structural glasses. The analys...

We report the emergence of the D band Raman mode in single-walled carbon nanotubes under large axial strain. The D to G mode Raman intensity ratio (ID/IG) is observed to increase with strain quadratically by more than a factor of 100-fold. Up to 5% strain, all changes in the Raman spectra are reversible. The emergence of the D band, instead, arises from the reversible and elastic symmetry-lower...

Buckling of single-walled and multiwalled carbon nanotubes SWNTs and MWNTs, respectively due to axial compressive loads has been studied by molecular mechanics simulations, and results compared with those from the analysis of equivalent continuum structures using Euler buckling theory and the finite element method. It is found that a MWNT of large aspect ratio length/diameter buckles as a colum...

The authors report the formation and optical characteristics of type-II, strain-relieved, and densely stacked GaSb/GaAs quantum dots QDs using an interfacial misfit IMF growth mode. A moderate V/III ratio during the growth of GaSb QDs produces strain-relieved QDs facilitated by the IMF array without Sb segregation associated with defects and threading dislocations. In contrast, a low V/III rati...

Nonadiabatic tapers in hollow-core air-silica photonic bandgap fibers (PBFs) were fabricated by the use of a fiber fusion splicer. In addition to the well-known scaling down of fiber dimensions, the innermost rings of air holes were found collapsed or significantly deformed, which results in almost doubling the diameter of the hollow core in the tapered region. The tapering of the PBF causes co...

Two parameters are identified for characterizing the deformation in the plastic zone near the tip of a crack when mixed mode conditions prevail. Details of the near-tip stress and strain distributions are presented f or hardening materials in which a diffus e plastic zone occurs under plane stress conditions. For small scale yielding the two near-tip parameters are related to the two elastic s ...

We report the strain effect of suspended graphene prepared by micromechanical method. Under a fixed measurement orientation of scattered light, the position of the 2D peaks changes with incident polarization directions. This phenomenon is explained by a proposed mode in which the peak is effectively contributed by an unstrained and two uniaxial-strained sub-areas. The two axes are tensile strai...

We employ x-ray scattering on sheared colloidal suspensions and mode coupling theory to study structure factor distortions of glass-forming systems under shear. We find a transition from quadrupolar elastic distortion at small strains to quadrupolar and hexadecupolar modes in the stationary state. The latter are interpreted as signatures of plastic rearrangements in homogeneous, thermalized sys...