RanBP1 Couples Nuclear Export and Golgi Regulation through LKB1 to Promote Cortical Neuron Polarity

Neuronal polarity in the developing cortex begins during the early stages of neural progenitor migration toward the cortical plate and culminates with the specification of the axon and dendrites. Here, we demonstrate that the Ran-dependent nucleocytoplasmic transport machinery is essential for the establishment of cortical neuron polarity. We found that Ran-binding protein 1 (RanBP1) regulates axon specification and dendritic arborization in cultured neurons in vitro and radial neural migration in vivo. During axonogenesis, RanBP1 regulates the cytoplasmic levels of the polarity protein LKB1/Par4, and this is dependent on the nuclear export machinery. Our results show that downstream of RanBP1, LKB1 function is mediated by the STK25-GM130 pathway, which promotes axonogenesis through Golgi regulation. Our results indicate that the nucleocytoplasmic transport machinery is a main regulator of neuron polarity, including radial migration, and that the regulated export of LKB1 through RanBP1 is a limiting step of axonogenesis

Typhusoomplicationen.

Diss. Berlin.OPLADEN-RUG0

Urkunden-Buch zur Geschichte des Geschlechts von Kröcher

[August Henning von Kröcher]In Fraktu

Geschichte des Geschlechts von Kröcher

[August Hennig von Kroecher]In Fraktu

Increased nickel exsolution from LaFe0.8Ni0.2O3 perovskite-derived CO2 methanation catalysts through strontium doping

Perovskite-derived Ni catalysts offer the remarkable benefit of redox stability that allows their regeneration after deactivation through poisoning or Ni particle growth. Here, the catalytic activity of LaFe0.8Ni0.2O3 towards CO2 methanation was improved by increasing Ni reducibility and segregation to the perovskite surface through partial substitution of La by Sr (La1-xSrxFe0.8Ni0.2O3-delta, 0 <= x <= 0.1). Temperature programmed reduction, X-ray diffraction, scanning electron microscopy and X-ray absorption spectroscopy were used to characterize the materials, their stability against severe reduction at high temperatures and to quantify Ni segregation. It is shown that Ni reducibility was significantly increased (up to 50%) upon introduction of Sr, because more Ni was exsoluted during catalyst pre-reduction. Nickel reincorporation into the perovskite-type oxide lattice during reoxidation was not affected at these Sr levels and complete redox stability could be demonstrated for all compositions investigated in this work

VOx Surface Coverage Optimization of V2O5/WO3-TiO2 SCR Catalysts by Variation of the V Loading and by Aging

V2O5/WO3-TiO2 selective catalytic reduction (SCR) catalysts with a V2O5 loading of 1.7, 2.0, 2.3, 2.6, 2.9, 3.2 and 3.5 wt. % were investigated in the fresh state and after hydrothermal aging at 600 degrees C for 16 h. The catalysts were characterized by means of nitrogen physisorption, X-ray diffraction and X-ray absorption spectroscopy. In the fresh state, the SCR activity increased with increasing V loading. Upon aging, the catalysts with up to 2.3 wt. % V2O5 exhibited higher NOx reduction activity than in the fresh state, while the catalysts with more than 2.6 wt. % V2O5 showed increasing deactivation tendencies. The observed activation and deactivation were correlated with the change of the VOx and WOx surface coverages. Only catalysts with a VOx coverage below 50% in the aged state did not show deactivation tendencies. With respect to tungsten, above one monolayer of WOx, WO3 particles were formed leading to loss of surface acidity, sintering, catalyst deactivation and early NH3 slip. An optimal compromise between activity and hydrothermal aging resistance could be obtained only with V2O5 between 2.0 and 2.6 wt. %

CO Methanation for Synthetic Natural Gas Production

Energy from woody biomass could supplement renewable energy production towards the replacement of fossil fuels. A multi-stage process involving gasification of wood and then catalytic transformation of the producer gas to synthetic natural gas (SNG) represents progress in this direction. SNG can be transported and distributed through the existing pipeline grid, which is advantageous from an economical point of view. Therefore, CO methanation is attracting a great deal of attention and much research effort is focusing on the understanding of the process steps and its further development. This short review summarizes recent efforts at Paul Scherrer Institute on the understanding of the reaction mechanism, the catalyst deactivation, and the development of catalytic materials with benign properties for CO nnethanation

Promotion of Ammonium Formate and Formic Acid Decomposition over Au/TiO2 by Support Basicity under SCR-Relevant Conditions

This work demonstrates the rational design of a dedicated hydrolysis catalyst for application in the selective catalytic reduction (SCR) of NOx. Modification of titania by lanthanum prior to gold deposition entailed highly improved catalytic activities for ammonium formate (AmFo) and formic acid decomposition under SCR-relevant conditions stemming from dual phenomena: particle size effect and base effect. Smaller gold particles were stabilized, and there was higher uptake of CO2 and formic acid, as demonstrated by HAADF-STEM and in situ DRIFT analyses, respectively. The difference in the activities between the lanthanum-modified, unmodified, and tungsten-modified catalysts was implicitly dictated by the formic acid coverage, which was in turn greatly increased in the presence of base. In situ DRIFT studies under reaction conditions identified formate as a relevant reaction intermediate, under reaction conditions. Higher E-a,E-app alongside a higher pre-exponential factor (A), describe an underlying compensation effect originating from the contribution of enthalpy associated with the desorption of the strongly adsorbed formate, which is consistent with the highly negative formic acid orders observed in the case of the lanthanum-modified catalysts. Gold is essential to achieve selectivity to CO2; its absence yields CO. The introduction of lanthanum to the catalytic system preferentially promoted the CO2 formation mechanism, enabling complete decomposition of formic acid selectively to CO2 at significantly lower gold loading and lower contact times, making it a promising candidate for decomposition of formate-based ammonia precursors in the SCR process

Strukturatlas 95/96: regionale Strukturen und Entwicklungstendenzen in Nordwestdeutschland

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