The medial entorhinal cortex is necessary for temporal organization of hippocampal neuronal activity.

The superficial layers of the medial entorhinal cortex (MEC) are a major input to the hippocampus. The high proportion of spatially modulated cells, including grid cells and border cells, in these layers suggests that MEC inputs are critical for the representation of space in the hippocampus. However, selective manipulations of the MEC do not completely abolish hippocampal spatial firing. To determine whether other hippocampal firing characteristics depend more critically on MEC inputs, we recorded from hippocampal CA1 cells in rats with MEC lesions. Theta phase precession was substantially disrupted, even during periods of stable spatial firing. Our findings indicate that MEC inputs to the hippocampus are required for the temporal organization of hippocampal firing patterns and suggest that cognitive functions that depend on precise neuronal sequences in the hippocampal theta cycle are particularly dependent on the MEC

Silicon oxycarbonitride ceramic containing nickel nanoparticles from design to catalytic application

Nickel containing silicon oxycarbonitride ceramic nanocomposites are synthesized from hydrous nickel acetate and poly vinyl silazane Durazane 1800 or perhydropolysilazane NN120 20 A PHPS . A room temperature chemical reaction results in Ni containing polysilazane precursors which are transformed into ceramic nanocomposites with nickel nanoparticles 2 4 nm upon pyrolysis at elevated temperatures 700 1100 C under an argon atmosphere. The ceramic nanocomposites derived from the Durazane 1800 Ni precursor by the thermolysis process at 700 and 900 C manifest a microporous structure with a BET specific surface area of amp; 8764;361 and amp; 8764;232 m2 g amp; 8722;1, respectively. In contrast, all pyrolyzed samples derived from the PHPS Ni precursor exhibit a nonporous structure. The Ni SiOCN ceramic nanocomposites tested in a plug flow fixed bed reactor display significant catalytic activity in dry methane reforming to syngas. The highest CH4 reaction rate of 0.18 mol min amp; 8722;1 gNi amp; 8722;1 is observed at 800 C for the sample derived from the PHPS Ni precursor by pyrolysis at 900 C. All these make the materials developed in this work, i.e. nickel nanoparticles in situ formed in the SiOCN ceramic matrix, as promising candidates for heterogeneous catalysi

A laboratory spectrometer for high throughput X-ray emission spectroscopy in catalysis research

We have built a laboratory spectrometer for X-ray emission spectroscopy. The instrument is employed in catalysis research. The key component is a von Hamos full cylinder optic with Highly Annealed Pyrolytic Graphite (HAPG) as a dispersive element. With this very efficient optic, the spectrometer subtends an effective solid angle of detection of around 1 msr, allowing for the analysis of dilute samples. The resolving power of the spectrometer is approximately E/ΔE = 4000, with an energy range of ∼2.3 keV–10 keV. The instrument and its characteristics are described herein. Further, a comparison with a prototype spectrometer, based on the same principle, shows the substantial improvement in the spectral resolution and energy range for the present setup. The paper concludes with a discussion of sample handling. A compilation of HAPG fundamentals and related publications are given in a brief Appendix.EC/FP7/615414/EU/Spectroscopic Studies of N2 Reduction: From Biological to Heterogeneous Catalysis/N2RE

Insights into structure and dynamics of (Mn,Fe)O_x-promoted Rh nanoparticles

The mutual interaction between Rh nanoparticles and manganese/iron oxide promoters in silica-supported Rh catalysts for hydrogenation of CO to higher alcohols was analyzed by applying a combination of integral techniques including temperature-programmed reduction (TPR), X-ray photoelectron spectroscopy (XPS), X-ray absorption (XAS) and Fourier transform infrared (FTIR) spectroscopy with local analysis by using high angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) in combination with energy dispersive X-ray spectroscopy (EDX). The promoted catalysts show reduced CO adsorption capacity as evidenced by FTIR spectroscopy, which is attributed to a perforated core-shell structure of the Rh nano-particles in accordance with the microstructural analysis by electron microscopy. Iron and manganese occur in low formal oxidation states between 2+ and zero in the reduced catalysts as shown by TPR and XAS. Infrared spectroscopy measured in diffuse reflectance at reaction temperature and pressure indicates that partial coverage of the Rh particles is maintained at reaction temperature under operation and that the remaining accessible metal adsorption sites might be catalytically less relevant because hydrogenation of adsorbed carbonyl species at 523 K and 30 bar hydrogen essentially failed. It is concluded that Rh⁰ is poisoned due to adsorption of CO under reaction conditions of CO hydrogenation. The active sites are associated either with a (Mn,Fe)O_x (x<0.25) phase or species at the interface between Rh and its co-catalyst (Mn,Fe)O_x