A combined experimental and theoretical study of the generation of palladium clusters on Au(111) with a scanning tunnelling microscope

Palladium clusters have been deposited on the surface of a Au(111) electrode with the tip of a scanning tunnelling microscope. The distance over which the tip was moved towards the surface has a decisive influence on the properties of the clusters: the larger this distance, the larger the generated clusters, and the more stable they are. These findings are supported by computer simulations, which further suggest that the larger clusters contain a sizable amount of gold, which enhances their stability. Dissolution of the clusters occurs from the edges rather than layer by layer.

Understanding the dehydrogenation mechanism of tetrahydrocarbazole over palladium using a combined experimental and density functional theory approach

The mechanism of the dehydrogenation of tetrahydrocarbazole to carbazole over palladium has been examined for the first time. By use of a combination of deuterium exchange experiments and density functional theory calculations, a detailed reaction profile for the aromatization of tetrahydrocarbazole has been identified and validated by experiment. As with many dehydrogenation reactions, the initial hydrogen abstraction is found to have the highest reaction barrier. Tetrahydrocarbazole has four hydrogens which can, in principle, be cleaved initially; however, the theory and experiment show that the reaction is dominated by the cleavage of the carbon hydrogens at the carbon atoms in positions 1 and 4. The two pathways originating from these two C-H bond cleavage processes are found to have similar reaction energy profiles and both contribute to the overall reaction.

Purification capacity of a highly loaded laboratory scale tidal flow reed bed system with effluent recirculation

The purification capacity of a laboratory scale tidal flow reed bed system with final effluent recirculation at a ratio of 1:1 was investigated in this study. In particular, this four-stage reed bed system was highly loaded with strong agricultural wastewater. Under the hydraulic and organic loading rates as high as 0.43 m3/m2d and 1055 gCOD/m2d, respectively, the average removal efficiencies of COD, BOD5, SS, NH4-N and P were 77%, 78%, 66%, 62% and 38%. Even with the high loading rates, approximately 30% of NH4-N was converted into NO2-N and NO3-N from the mid-stage of the system where nitrification took place. The results suggest that the multi-stage reed bed system could be employed to treat strong wastewater under high loading, especially for the substantive mass removal of solids, organic matter and ammoniacal-nitrogen. Tidal flow combined with effluent recirculation is a favourable operation strategy to achieve this objective.

Proposed wavelet-neurofuzzy combined system for power qualityviolations detection and diagnosis

A system for the identification of power quality violations is proposed. It is a two-stage system that employs the potentials of the wavelet transform and the adaptive neurofuzzy networks. For the first stage, the wavelet multiresolution signal analysis is exploited to denoise and then decompose the monitored signals of the power quality events to extract its detailed information. A new optimal feature-vector is suggested and adopted in learning the neurofuzzy classifier. Thus, the amount of needed training data is extensively reduced. A modified organisation map of the neurofuzzy classifier has significantly improved the diagnosis efficiency. Simulation results confirm the aptness and the capability of the proposed system in power quality violations detection and automatic diagnosis