Paul Scherrer Institute

About: Paul Scherrer Institute is a facility organization based out in Villigen, Switzerland. It is known for research contribution in the topics: Neutron & Large Hadron Collider. The organization has 9248 authors who have published 23984 publications receiving 890129 citations. The organization is also known as: PSI.

Measurement of the differential cross section for top quark pair production in pp collisions at √s=8 TeV

Abstract: The normalized differential cross section for top quark pair (tt) production is measured in pp collisions at a centre-of-mass energy of 8TeV at the CERN LHC using the CMS detector in data corresponding to an integrated luminosity of 19.7fb^(−1). The measurements are performed in the lepton+jets (e/μ +jets) and in the dilepton (e^+e^−, μ^+μ^−, and e^±μ^∓) decay channels. The tt cross section is measured as a function of the kinematic properties of the charged leptons, the jets associated to b quarks, the top quarks, and the tt system. The data are compared with several predictions from perturbative quantum chromodynamic up to approximate next-to-next-to-leading-order precision. No significant deviations are observed relative to the standard model predictions.

Radiation Grafted Membranes for Polymer Electrolyte Fuel Cells

Abstract: The cost of polymer electrolyte fuel cell (PEFC) components is crucial to the commercial viability of the technology. Proton exchange membranes fabricated via the method of radiation grafting offer a cost-competitive option, because starting materials are inexpensive commodity products and the preparation procedure is based on established industrial processes. Radiation grafted membranes have been used with commercial success in membrane separation technology. This review focuses on the application of radiation grafted membranes in fuel cells, in particular the identification of fuel cell relevant membrane properties, aspects of membrane electrode assembly (MEA) fabrication, electrochemical performance and durability obtained in cell or stack tests, and investigation of failure modes and post mortem analysis. The application in hydrogen and methanol fuelled cells is treated separately. Optimized styrene / crosslinker grafted and sulfonated membranes show performance comparable to perfluorinated membranes. Some properties, such as methanol permeability, can be tailored to be superior. Durability of several thousand hours at practical operating conditions has been demonstrated. Alternative styrene derived monomers with higher chemical stability offer the prospect of enhanced durability or higher operating temperature.

Catalytic oxidation of nitrogen monoxide over Pt/SiO2

Abstract: The catalytic oxidation of NO was studied on a catalyst consisting of platinum supported on SiO2. The kinetic behavior over Pt/SiO2 with a platinum loading of 2.5 wt.% was investigated in a feed containing 5% water and various concentrations of oxygen, nitrogen monoxide and nitrogen dioxide. The conversion of NO to NO2 increases when the oxygen concentration is increased from 0.1 to 10%, but levels off at higher concentrations. Increasing feed concentrations of NO lead to a decrease in the conversion to NO2. The formation of NO2 is also depressed by the addition of NO2 to the feed. Both observations suggest that the oxidation of NO on Pt/SiO2 is autoinhibited by the reaction product NO2. Further experiments have shown that the inhibition caused by NO2 is mostly persistent, i.e. a deactivation of the catalyst occurs. A pretreatment at 250 °C in a feed containing 500 ppm NO2 causes a very strong decrease in activity. However, the initial activity can be restored either by a thermal regeneration at 650 °C in air or by a regeneration under reducing conditions at 250 °C, e.g. in a feed containing NH3. This suggests that the deactivation by NO2 is due to the formation of a thin layer of platinum oxide covering the platinum surface at least partially.