Self-organized growth of nanoparticles on a surface patterned by a buried dislocation network

The self-organized growth of Co nanoparticles is achieved at room temperature on an inhomogenously strained Ag(001) surface arising from an underlying square misfit dislocation network of 10 nm periodicity buried at the interface between a 5 nm-thick Ag film and a MgO(001) substrate. This is revealed by in situ grazing-incidence small-angle x-ray scattering. Simulations of the data performed in the distorted wave Born approximation framework demonstrate that the Co clusters grow above the dislocation crossing lines. This is confirmed by molecular dynamic simulations indicating preferential Co adsorption on tensile sites.     

Retarded Green Functions and Modified Dispersion Relations

We analyse a three-field model, which describes a relativistic two-level atom interactingwith a radiation bath. From the one-loop retarded propagators at finite temperature we extract the transition rates and the modifications of the dispersion relations. To further investigate the relationships between propagators and these physical quantities, we analyse a non-equilibrium situation in which an additional atom is present in the bath. Preliminary results indicate that transition rates can still be extracted from the (retarded) propagator. This approach couldtherefore be useful in relating high-frequency (trans-Planckian) dispersion relations to the physical processes occurring at these scales.     

Enantioselective Ring Opening of Aza and Oxabicyclic Alkenes with Dimethylzinc

A system for efficient, asymmetric alkylative ring opening of azabenzonorbornadienes and [2.2.1] and [3.2.1] oxabicyclic alkenes was developed. The use of Pd(CH(3)CN)(2)Cl(2) and chiral phosphinooxazoline ligands gives the dihydronaphthalenes, cyclohexenols, and cycloheptenols in excellent yields and enantiomeric excesses.     

Atomic structure of the polar NiO(111)- p(2x2) surface

Using grazing-incidence x-ray diffraction, the p(2x2) surface structures of the single crystal NiO(111) and a 5 monolayer thick NiO(111) film on Au(111) were both shown to exhibit locally the theoretically predicted octopolar reconstruction, with some important differences. The single crystal exhibits a single Ni termination with double steps. The thin film exhibits both possible terminations (O and Ni) and single steps. These surfaces were found to be nonreactive with respect to hydroxylation.     

Enantioselective access to 2,7-cis-disubstituted oxepanes: formal synthesis of (+)-isolaurepan

[reaction: see text] The asymmetric synthesis of 2,7-cis-disubstituted oxepanes bearing a sulfoxide is achieved from commercially available precursors in only five steps. The key step is the highly diastereoselective Et3SiH/TMSOTf-promoted reductive cyclization of enantiopure hydroxysulfinyl aryl or alkyl ketones.     

Nodal order parameter in electron-doped Pr(2-x)CexCuO(4-delta) superconducting films

The London penetration depth, lambda(ab)(T), is reported for thin films of the electron-doped superconductor Pr(2-x)Ce(x)CuO(4-delta) with varying Ce concentration, x=0.13, 0.15, and 0.17. Measurements down to 0.35 K were carried out using a tunnel-diode oscillator with excitation fields applied both perpendicular and parallel to the conducting planes. Films at all three doping levels exhibited power law behavior indicative of d-wave pairing with impurity scattering. These results are fully consistent with previous measurements on single crystals.     

Spectrofluorimetric determination of formaldehyde in maple syrup

A quick and simple method was developed for determination of formaldehyde in maple syrup. In this method, formaldehyde reacts with Fluoral P to form a complex which is chemically extracted by isobutanol and determined by spectrofluorimetry. Performance, as gauged by the limits of detection (0.16 mg/kg) and quantitation (0.21 mg/kg), recovery (>79%), and variability (1.9-16.1%, depending on fortification level and class of syrup) were superior to the current official AOAC standard method.