Study of Uniaxial Tensile Properties of Hexagonal Boron Nitride Nanoribbons

Uniaxial tensile properties of hexagonal boron nitride nanoribbons and dependence of these properties on temperature, strain rate, and the inclusion of vacancy defects have been explored with molecular dynamics simulations using Tersoff potential. The ultimate tensile strength of pristine hexagonal boron nitride nanoribbon of 26 nm x 5 nm with armchair chirality is found to be 100.5 GPa. The ultimate tensile strength and strain have been found decreasing with increasing the temperature while an opposite trend has been observed for increasing the strain rate. Furthermore, the vacancy defects reduce ultimate tensile strength and strain where the effect of bi-vacancy is clearly dominating over point vacancy

Supernova neutrino induced neutrons in liquid xenon dark matter detectors

Neutrinos from supernova (SN) bursts can give rise to detectable number of nuclear recoil (NR) events through the process of coherent elastic neutrino-nucleus scattering (CE$\nu$NS) in future large (multi-ton scale) liquid xenon detectors employed for dark matter search depending on the SN progenitor mass and distance to the SN event. Here we point out that in addition to the direct NR events due to CE$\nu$NS process, there is a secondary source of nuclear recoils due to elastic scattering of the neutrons produced through inelastic neutrino-nucleus scattering of the supernova neutrinos with the target xenon nuclei. We estimate the contribution of these supernova neutrino-induced neutrons ($\nu$In) to the total xenon NR spectrum and find that the latter can be significantly modified at large recoil energies from that expected from the CE$\nu$NS process alone, with the $\nu$In contribution dominating the total integral recoil energy spectrum at recoil energies above $\sim$20 keV. With the capability to measure the energies of individual recoil events, sufficiently large liquid xenon detectors may be able to detect these events due to $\nu$In process triggered by neutrinos from reasonably close by SN burst events. We also note that the $\nu$In contribution to the recoil spectrum receives dominant contribution from the charged current interaction of the SN $\nu_e$s with the target nuclei while the CE$\nu$NS contribution comes from neutral current interactions of all the six species of neutrinos with the target nuclei. This may offer the possibility of extracting useful information about the distribution of the total SN explosion energy going into different neutrino flavors.Comment: Replaced with revised version; includes results of GEANT4 simulation of neutron induced xenon nuclear recoils; one additional author (SG); figures modified; 2 new figures; main conclusions remain unchanged; latex 9 pages with 6 figure

Active emulsions in living cell membranes driven by contractile stresses and transbilayer coupling

The spatiotemporal organisation of proteins and lipids on the cell surface has direct functional consequences for signaling, sorting and endocytosis. Earlier studies have shown that multiple types of membrane proteins including transmembrane proteins that have cytoplasmic actin binding capacity and lipid-tethered GPI-anchored proteins (GPI-APs) form nanoscale clusters driven by active contractile flows generated by the actin cortex. To gain insight into the role of lipids in organizing membrane domains in living cells, we study the molecular interactions that promote the actively generated nanoclusters of GPI-APs and transmembrane proteins. This motivates a theoretical description, wherein a combination of active contractile stresses and transbilayer coupling drive the creation of active emulsions, mesoscale liquid ordered (lo) domains of the GPI-APs and lipids, at temperatures greater than equilibrium lipid-phase segregation. To test these ideas we use spatial imaging of homo-FRET combined with local membrane order and demonstrate that mesoscopic domains enriched in nanoclusters of GPI-APs are maintained by cortical actin activity and transbilayer interactions, and exhibit significant lipid order, consistent with predictions of the active composite model