We study the interactions between Fe(II) aqua-complexes and surfaces of goethite (α-FeOOH) by means of density-functional theory calculations including the so-called Hubbard U correction to the exchange-correlation functional. Using a thermodynamic approach, we find that (110) and (021) surfaces in contact with aqueous solutions are almost equally stable, despite the evident needle-like shape of goethite crystals indicating substantially different reactivity of the two faces. We thus suggest that crystal anisotropy may result from different growth rates due to virtually barrier-less adsorption of hydrated ions on the (021) but not on the (110) surface. No clear evidence is found for spontaneous electron transfer from an adsorbed Fe(II) hex-aqua complex to a defect-free goethite substrate. Crystal defects are thus inferred to play an important role in assisting such electron transfer processes observed in a recent experimental study. Finally, goethite surfaces are observed to enhance the partial oxidation of adsorbed aqueous Fe(II) upon reaction with molecular oxygen.We propose that this catalytic oxidation effect arises from donation of electronic charge from the bulk oxide to the oxidizing agent through shared hydroxyl ligands anchoring the Fe(II) complexes on the surface.PACS numbers: 71.15.Mb

The vapor phase vacuum ultraviolet absorption spectra of methyl bromide, methylene bromide, bromoform, and carbon tetrabromide are reported for the region 40 000−90 000 cm−1 (250−110 nm). Many of the Rydberg and intravalent absorptions of the bromine electrons in the nonbonding p orbitals, which are perpendicular to the C−Br bonding axes, and the σ*←σ (C−Br) absorptions of the compounds have been assigned. A correlation of the molecular Rydberg series of methyl bromide to series in krypton, which has made possible the assignment of the 4d and 4f Rydberg absorptions, is presented. Expanded vibrational progressions of the first ns and np Rydberg transitions of methylbromide are presented. The analysis of these progressions indicates that transitions to the 5s and 5p Rydberg orbitals bring about a Jahn−Teller distortion of the molecule. Three ns Rydberg series of methylene bromide were assigned which converge on the ionization potentials of 10.629±0.010, 10.839±0.010, and 11.261±0.010 eV. The states formed upon ionization are assigned as the b2, b1, and a1, respectively, as the ns transitions of the a2 combination of bromine p orbitals are forbidden in C2v symmetry. Other absorptions of methylene bromide, as well as the majority of the first ns, np, and nd molecular Rydberg assignments of bromoform and carbon tetrabromide were made using the term values of the bands with respect to the ionization potentials of the molecules. It was found that the averaged ns term values of the bromomethanes vary slightly through the series, while the np term values were increased in methylene bromide and bromoform. In each spectrum the assignment of the σ*←σ (C−Br) bands was made based on an empirically derived relation.

1. Quantifying movement and demographic events of free-ranging animals is fundamental to studying their ecology, evolution and conservation. Technological advances have led to an explosion in sensor-based methods for remotely observing these phenomena. This transition to big data creates new challenges for data management, analysis and collaboration.2. We present the Movebank ecosystem of tools used by thousands of researchers to collect, manage, share, visualize, analyse and archive their animal tracking and other animal-borne sensor data. Users add sensor data through file uploads or live data streams and further organize and complete quality control within the Movebank system. All data are harmonized to a data model and vocabulary. The public can discover, view and download data for which they have been given access to through the website, the Animal Tracker mobile app or by API. Advanced analysis tools are available through the EnvDATA System, the MoveApps platform and a variety of user-developed applications. Data owners can share studies with select users or the public, with options for embargos, licenses and formal archiving in a data repository.3. Movebank is used by over 3,100 data owners globally, who manage over 6 billion animal location and sensor measurements across more than 6,500 studies, with thousands of active tags sending over 3 million new data records daily. These data underlie >700 published papers and reports. We present a case

The reaction of sodium nitrite in aqueous acetonitrile (3:2) at pH 7 and 25°with the four 2,4-dinitrohalobenzenes clearly demonstrates the ambident nature of the nitrite ion. The relative importance of the two modes of displacement, O attack and N attack, depends on the halogen displaced, oxygen attack increasing with increasing electronegativity of the halogen. Dinitrofluorobenzene reacts totally by O attack, whereas dinitroiodobenzene reacts altogether by N attack. Dinitrochloroand dinitrobromobenzene demonstrate both modes of displacement. The rates of oxygen and nitrogen attack by nitrite ion were determined for each of the 2,4-dinitrohalobenzenes, and the rate of oxygen attack was determined for 1,2,4-trinitrobenzene.