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Gold-doped palladium clusters, Au2Pdn (n = 1~4), are investigated using the density functional method B3LYP with relativistic effective core potentials (RECP) and LANL2DZ basis set. The possible geometrical configurations with their electronic states are determined, and the stability trend is investigated. Several low-lying isomers are determined, and many of them are in electronic configurations with a high-spin multiplicity. Our results indicate that the palladium-gold interaction is strong enough to modify the known pattern of bare palladium clusters, and the lower stability as the structures grow in size. The present calculations are useful to understanding the enhanced catalytic activity and selectivity gained by using gold-doped palladium catalyst.

The geometries of the lowest-lying isomers of Au n Pt 2 , ( n =1–4), clusters are determined using the density functional method B3LYP with relativistic effective core potentials (RECP) and LANL2DZ basis set. Several low-lying isomers were determined, and many of them in electronic configurations with a high spin multiplicity. The stability trend of Pt-doped Au n clusters are compared to that of pure Au n clusters. Our results show that the gold–platinum interaction is strong enough to improve the cluster stability, and indicate that the larger the Au n cluster is, smaller the distortions by substitution of the two Pt atoms are.

Palladium-doped gold clusters, AunPd2 ( n = 1 – 4 ), were investigated by two Pd-atom substitutions on the Aun clusters using the density functional method Becke3LYP with relativistic effective core potentials (RECP) and LANL2DZ basis set. The possible stable geometrical configurations with their electronic states are determined, and the stability trend of Pd-doped Aun clusters are compared to that of pure Aun clusters. Our results show that the gold–palladium interaction is strong enough to modify the known growth pattern of bare gold clusters, and indicate that the larger the Aun cluster is, smaller the distortions by the two Pd-atom substitutions are. The present calculations are useful to understand the enhanced catalytic activity and selectivity gained by using palladium-doped gold catalyst.

Density functional calculations have been performed for the structural, electronic, and magnetic properties of Au5M (M = Sc-Zn) clusters. Geometry optimizations indicate that the M atoms in low-energy Au5M isomers prefer to occupy the most highly coordinated position. The ground-state clusters except Au5Sc possess a planar structure. The vibrational spectra of the doped clusters are completely different from that of a pure gold cluster. The relative stability and chemical activity are investigated through the averaged binding energy and energy gap for the most stable Au5M clusters. It is found that the impurity atoms (not including the Zn atom) can enhance the thermal stability of the host cluster. The chemical activity of Au5M clusters is higher than that of the Au6 cluster. The calculated energy gaps are in accord with available approximate experimental data. The vertical ionization potential, the electron affinity, and photoelectron spectrum are computed and simulated theoretically for all of the ground-state clusters. The magnetism analyses show that the magnetic moment of these Au5M clusters varies from 0 to 5 μB by substituting a Au atom in a Au6 cluster with various M atoms and is mainly localized on the M atom for M = Ti-Ni.

This work investigated the effect of physiochemical conditions of fermentation on the de-emulsification capability of biological de-emulsifier production by a demulsifying strain(a Bacillus sp. isolated by our laboratory from oil contaminated soil). A quadratic orthogonal regressive rotation design was used to establish an effective statistical model for evaluation the combined effects of the incubation time(A), culturing temperature(B), glucose concentration(C) in substrate, in oculum age(D) and shaker agitation(E). The results of analysis of variance (ANOVA) of face-centered central composite design (FCCCD) showed that the adequately high R2 value of 0.976 and F-value of 30.69 indicated the statistical significance of the quadratic model which there were seven significant model terms (Prob>F

Bio-demulsifier as a biological agent will become a substitute of chemical demulsifier for its high efficiency, low cost, high adoptability and environment friendly. In this paper, a set of high efficiency, rapid and simple method was established to isolate deemulsification strains. Blue-gel plates test, oil agar plates test, oil-spreading test and demulsifying test were combined used in this method. Using this method, ten strains with high de-emulsification capability which the demulsifying ratios in O/W Kerosene emulsion (in 24h)were more than 50% were primary screened from activated sludge samples. Two highly efficient demulsifying strains which the demulsifying ratio in O/W Kerosene emulsion (in 24h) were more than 90%were secondary isolated and identified as Gordonia sp. through 16S rDNA gene and physiological test. The whole culture of the strain appeared very high deemulsification activity with low biomass.