On the Formation of Copper Linear Atomic Suspended Chains

We report high resolution transmission electron microscopy and classical molecular dynamics simulation results of mechanically stretching copper nanowires conducting to linear atomic suspended chains (LACs) formation. In contrast with some previous experimental and theoretical work in literature that stated that the formation of LACs for copper should not exist our results showed the existence of LAC for the [111], [110], and [100] crystallographic directions, being thus the sequence of most probable occurence.Comment: 4 pages, 3 figure

Access to a diverse array of bridged benzo[1,5]oxazocine and benzo[1,4]diazepine structures

The preparation of bridged benzo[1,5]oxazocines and benzo[1,4]diazepines is demonstrated from simple aniline and aldehyde starting materials. A one-pot condensation/6π electrocyclization is followed by an intramolecular trapping of the 2,3-dihydroquinoline intermediate by nitrogen or oxygen nucleophiles to give bridged seven- and eight-membered products. Using 3-hydroxypyridinecarboxaldehydes results in a stable zwitterionic structure that can undergo a diastereoselective reduction under hydrogenative conditions. A similar cyclization/hydrogenation pathway with excellent diastereoselectivity is also demonstrated from 2-pyridyl-substituted 1,2,3,4-tetrahydroquinolines.PostprintPeer reviewe

Magnetic friction due to vortex fluctuation

We use Monte Carlo and molecular dynamics simulation to study a magnetic tip-sample interaction. Our interest is to understand the mechanism of heat dissipation when the forces involved in the system are magnetic in essence. We consider a magnetic crystalline substrate composed of several layers interacting magnetically with a tip. The set is put thermally in equilibrium at temperature T by using a numerical Monte Carlo technique. By using that configuration we study its dynamical evolution by integrating numerically the equations of motion. Our results suggests that the heat dissipation in this system is closed related to the appearing of vortices in the sample.Comment: 6 pages, 41 figure