569 research outputs found

    Identifying the Azobenzene/Aniline reaction intermediate on TiO2-(110) : a DFT Study

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    Density functional theory (DFT) calculations, both with and without dispersion corrections, have been performed to investigate the nature of the common surface reaction intermediate that has been shown to exist on TiO2(110) as a result of exposure to either azobenzene (C6H5N═NC6H5) or aniline (C6H5NH2). Our results confirm the results of a previous DFT study that dissociation of azobenzene into two adsorbed phenyl imide (C6H5N) fragments, as was originally proposed, is not energetically favorable. We also find that deprotonation of aniline to produce this surface species is even more strongly energetically disfavored. A range of alternative surface species has been considered, and while dissociation of azobenzene to form surface C6H4NH species is energetically favored, the same surface species cannot form from adsorbed aniline. On the contrary, adsorbed aniline is much the most stable surface species. Comparisons with experimental determinations of the local adsorption site, the Ti–N bond length, the molecular orientation, and the associated C 1s and N 1s photoelectron core level shifts are all consistent with the DFT results for adsorbed aniline and are inconsistent with other adsorbed species considered. Possible mechanisms for the hydrogenation of azobenzene required to produce this surface species are discussed

    Sensibilidade do carrapato Boophilus microplus a solventes.

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    A study was conducted to investigate the sensitivity of Boophilus microplus cattle ticks to different solvents. Larvae and engorged females of B. microplus were subjected to 7 solvents in 5 different concentrations in the presence and absence of olive oil. The utilization of olive oil did not produce different statistical results in the impregnated paper larval test. The same results were observed in the adult immersion test with hydrophilic compounds. The mean mortality caused by solvents was small in the larval test, and increased in immersion tests. Solvents with low molecular weight and viscosity such as alcohol and methyl alcohol did not affect the mortality of B. microplus in biological tests in concentrations below 76%.

    Magma displacements under insular volcanic fields, applications to eruption forecasting: El Hierro, Canary Islands, 2011-2013

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    Significant deformations, followed by increased seismicity detected since 2011 July at El Hierro, Canary Islands, Spain, prompted the deployment of additional monitoring equipment. The climax of this unrest was a submarine eruption first detected on 2011 October 10, and located at about 2 km SW of La Restinga, southernmost village of El Hierro Island. The eruption ceased on 2012 March 5, after the volcanic tremor signals persistently weakened through 2012 February. However, the seismic activity did not end with the eruption, as several other seismic crises followed. The seismic episodes presented a characteristic pattern: over a few days the number and magnitude of seismic event increased persistently, culminating in seismic events severe enough to be felt all over the island. Those crises occurred in 2011 November, 2012 June and September, 2012 December to 2013 January and in 2013 March-April. In all cases the seismic unrest was preceded by significant deformations measured on the island's surface that continued during the whole episode. Analysis of the available GPS and seismic data suggests that several magma displacement processes occurred at depth from the beginning of the unrest. The first main magma movement or 'injection' culminated with the 2011 October submarine eruption. A model combining the geometry of the magma injection process and the variations in seismic energy release has allowed successful forecasting of the new-vent opening.CSIC [2011-30E070]; MINECO [CGL2011-28682-C02-01]; bilateral UNAM (Mexico) - CSIC (Spain) program; Mayor's Office of El Pinar de El Hierroinfo:eu-repo/semantics/publishedVersio
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