In Situ X-ray Raman Scattering Spectroscopy of the Formation of Cobalt Carbides in a Co/TiO2 Fischer–Tropsch Synthesis Catalyst

We present in situ experiments to study the possible formation of cobalt carbides during Fischer–Tropsch synthesis (FTS) in a Co/TiO2 catalyst at relevant conditions of pressure and temperature. The experiments were performed by a combination of X-ray Raman scattering (XRS) spectroscopy and X-ray diffraction (XRD). Two different experiments were performed: (1) a Fischer–Tropsch Synthesis (FTS) reaction of an ∼14 wt % Co/TiO2 catalyst at 523 K and 5 bar under H2 lean conditions (i.e., a H2:CO ratio of 0.5) and (2) carburization of pure cobalt (as reference experiment). In both experiments, the Co L3-edge XRS spectra reveal a change in the oxidation state of the cobalt nanoparticles, which we assign to the formation of cobalt carbide (Co2C). The C K edge XRS spectra were used to quantify the formation of different carbon species in both experiments.Peer reviewe

Landscape structure, human disturbance and crop management affect foraging ground selection by migrating geese

It is well known that agricultural intensification has caused severe population declines among bird species which use farmland for breeding and overwintering, while migrating bird species may benefit from intensive farming, but in turn damage crops. Knowledge of the habitat selection of migrating birds is important from both a conservation and agro-economic point of view. We investigated the habitat preferences of three common migrating goose species: White-fronted Goose Anser albifrons, Bean Goose A. fabalis and Greylag Goose A. anser during the autumn of 2009 in western Poland. A total of 24 flocks of these species were identified. Geese preferred large, elevated fields that were remote from forests and human settlements but in close proximity to a lake. Geese selected maize stubbles and avoided winter cereals. They selected sites in landscapes with a lower diversity of crops. Flock size was negatively correlated with the proportion of pastures in the landscape, but it increased with field size, distance to forest and distance to town. Our results are in contrast with the paradigm that less intensive farmland positively influences habitat use by birds during foraging. We advise the delayed ploughing of stubbles with the aim of creating appropriate foraging habitats for geese and minimizing damage to cereal crops

25th annual computational neuroscience meeting: CNS-2016

The same neuron may play different functional roles in the neural circuits to which it belongs. For example, neurons in the Tritonia pedal ganglia may participate in variable phases of the swim motor rhythms [1]. While such neuronal functional variability is likely to play a major role the delivery of the functionality of neural systems, it is difficult to study it in most nervous systems. We work on the pyloric rhythm network of the crustacean stomatogastric ganglion (STG) [2]. Typically network models of the STG treat neurons of the same functional type as a single model neuron (e.g. PD neurons), assuming the same conductance parameters for these neurons and implying their synchronous firing [3, 4]. However, simultaneous recording of PD neurons shows differences between the timings of spikes of these neurons. This may indicate functional variability of these neurons. Here we modelled separately the two PD neurons of the STG in a multi-neuron model of the pyloric network. Our neuron models comply with known correlations between conductance parameters of ionic currents. Our results reproduce the experimental finding of increasing spike time distance between spikes originating from the two model PD neurons during their synchronised burst phase. The PD neuron with the larger calcium conductance generates its spikes before the other PD neuron. Larger potassium conductance values in the follower neuron imply longer delays between spikes, see Fig. 17.Neuromodulators change the conductance parameters of neurons and maintain the ratios of these parameters [5]. Our results show that such changes may shift the individual contribution of two PD neurons to the PD-phase of the pyloric rhythm altering their functionality within this rhythm. Our work paves the way towards an accessible experimental and computational framework for the analysis of the mechanisms and impact of functional variability of neurons within the neural circuits to which they belong

On the local structure of Ti during in situ desorption of Ti(OBu)(4) and TiCl3 doped NaAlH4

The local structures of Ti doped NaAlH4 were investigated with extended X-ray absorption fine structure (EXAFS) and X-ray absorption near edge structure (XANES) using Ti(OBU)(4) and TiCl3 precursors. The local structures were linked to literature data on hydrogen desorption and absorption kinetics. In the Ti(OBU)4 doped NaAlH4, butoxide or decomposition products thereof (C, 0 atoms) was bonded to Ti after ball-trulling, inhibiting the performance of the Ti catalyst. Upon heating, the C and 0 atoms were removed and Ti-Al species were formed. The thermodynamical most stable specie, TiAl3, was not formed at T<300 degrees C, contrarily to TiCl3 doped NaAlH4- Probably the initially present butoxide group gave rise to inhibition of its formation. Besides that, the butoxide or decompostion products thereof (C, 0 atoms) are also suspected to interfere with the hydrogen uptake of a desorbed NaAlH4. (C) 2006 Elsevier B.V. All rights reserved

On the local structure of Ti during in situ desorption of Ti(OBu)(4) and TiCl3 doped NaAlH4

The local structures of Ti doped NaAlH4 were investigated with extended X-ray absorption fine structure (EXAFS) and X-ray absorption near edge structure (XANES) using Ti(OBU)(4) and TiCl3 precursors. The local structures were linked to literature data on hydrogen desorption and absorption kinetics. In the Ti(OBU)4 doped NaAlH4, butoxide or decomposition products thereof (C, 0 atoms) was bonded to Ti after ball-trulling, inhibiting the performance of the Ti catalyst. Upon heating, the C and 0 atoms were removed and Ti-Al species were formed. The thermodynamical most stable specie, TiAl3, was not formed at T<300 degrees C, contrarily to TiCl3 doped NaAlH4- Probably the initially present butoxide group gave rise to inhibition of its formation. Besides that, the butoxide or decompostion products thereof (C, 0 atoms) are also suspected to interfere with the hydrogen uptake of a desorbed NaAlH4. (C) 2006 Elsevier B.V. All rights reserved