Trace metals (Cd, Cr, Cu, Ni and Pb) concentrations in benthic sediments were analyzed through multi-step fractionation scheme to assess the levels and sources of contamination in estuarine, riverine and freshwater ecosystems in Niger Delta (Nigeria). The degree of contamination was assessed using the individual contamination factors (ICF) and global contamination factor (GCF). Multivariate sta...

HRSEM analyses of copper/graphite interfaces are presented, showing a narrow solid solution zone. Atomistic simulations in the framework of the Generalized Simulated Annealing approach lead to very reasonable relaxed geometries around carbon interstitials and vacancy complexes of a Cu host, and for a Cu/graphite interface. Embedded Cluster Density Functional results indicate a charge transfer o...

The surface-enhanced Raman scattering (SERS) phenomenon of 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) adsorbed on Au20 pyramidal cluster is studied by Density Functional Theory. All possible adsorption configurations between the adsorbate and clusters are evaluated vibrational assignments normal SERS spectra analyzed. result shows that most stable configuration formed interaction O13 (-COOH gr...

We simulate the melting of a 71 Å diameter cluster of Cu. At low temperatures the crystal exhibits facets. With increasing temperatures the open facets pre–melt, the melted regions coalesce into a liquid envelope containing a crystalline nucleus, and the nucleus finally goes unstable to the supercooled liquid. Using critical droplet theory and experimental data for Cu, we explain the thermodyna...

The addition of Cu(I) to the random-coil peptide, C16C19-GGY, produces a self-organized, metal-bridged 4-helix bundle which displays an intense room-temperature luminescence at 600 nm. Emission, UV, and CD titrations along with X-ray absorption studies indicate that the luminescent cofactor is likely a Cu4S4 cluster in which each Cu atom is bridged by the side chains of two cysteine residues an...

Clusters of Cu (2+)(H 2O) n , n = 6-12, formed by electrospray ionization, are investigated using infrared photodissociation spectroscopy, blackbody infrared radiative dissociation (BIRD), and density functional theory of select clusters. At 298 K, the BIRD rate constants increase with increasing cluster size for n >or= 8, but the trend reverses for the smaller clusters where Cu (2+)(H 2O) 6 is...

Super-diffusion of Ag, Au and Cu clusters normal diffusion Pd cluster on graphene.

The structure of 38 atoms Ag-Cu cluster is studied by using a combination of a genetic algorithm global optimization technique and density functional theory (DFT) calculations. It is demonstrated that the truncated octahedral (TO) Ag32Cu6 core-shell cluster is less stable than the polyicosahedral (pIh) Ag32Cu6 core-shell cluster from the atomistic models and the DFT calculation shows an agreeab...

Motivated by the use of electrodes modified at the nanoscale by supported metal species, we studied computationally how the reactivity changes in such a composite system compared to the reactivity of the individual systems, metal clusters and metal surfaces. Specifically, we examined hydrogen adsorption on and hydrogen spillover from Au- and Cu-supported Pt(3) and Pd(3) clusters, using a method...