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.

Isothermal Cyclic Conversion of Methane into Methanol over Copper-Exchanged Zeolite at Low Temperature.

Abstract: Direct partial oxidation of methane into methanol is a cornerstone of catalysis. The stepped conversion of methane into methanol currently involves activation at high temperature and reaction with methane at decreased temperature, which limits applicability of the technique. The first implementation of copper-containing zeolites in the production of methanol directly from methane is reported, using molecular oxygen under isothermal conditions at 200 °C. Copper-exchanged zeolite is activated with oxygen, reacts with methane, and is subsequently extracted with steam in a repeated cyclic process. Methanol yield increases with methane pressure, enabling reactivity with less reactive oxidized copper species. It is possible to produce methanol over catalysts that were inactive in prior state of the art systems. Characterization of the activated catalyst at low temperature revealed that the active sites are small clusters of copper, and not necessarily di- or tricopper sites, indicating that catalysts can be designed with greater flexibility than formerly proposed.

Secondary organic aerosol formation from gasoline vehicle emissions in a new mobile environmental reaction chamber

Abstract: . We present a new mobile environmental reaction chamber for the simulation of the atmospheric aging of different emission sources without limitation from the instruments or facilities available at any single site. Photochemistry is simulated using a set of 40 UV lights (total power 4 KW). Characterisation of the emission spectrum of these lights shows that atmospheric aging of emissions may be simulated over a range of temperatures (−7 to 25 °C). A photolysis rate of NO2, JNO2, of (8.0 ± 0.7) × 10−3 s−1 was determined at 25 °C. We demonstrate the utility of this new system by presenting results on the aging (OH = 12 × 106 cm−3 h) of emissions from a modern (Euro 5) gasoline car operated during a driving cycle (New European Driving Cycle, NEDC) on a chassis dynamometer in a vehicle test cell. Emissions from the entire NEDC were sampled and aged in the chamber. Total organic aerosol (OA; primary organic aerosol (POA) emission + secondary organic aerosol (SOA) formation) was (369.8–397.5)10−3 g kg−1 fuel, or (13.2–15.4) × 10−3 g km−1, after aging, with aged OA/POA in the range 9–15. A thorough investigation of the composition of the gas phase emissions suggests that the observed SOA is from previously unconsidered precursors and processes. This large enhancement in particulate matter mass from gasoline vehicle aerosol emissions due to SOA formation, if it occurs across a wider range of gasoline vehicles, would have significant implications for our understanding of the contribution of on-road gasoline vehicles to ambient aerosols.

[11C]raclopride and positron emission tomography in previously untreated patients with Parkinson's disease Influence of L‐dopa and lisuride therapy on striatal dopamine D2‐receptors

Abstract: We studied cerebral dopamine D2-receptor binding using [11C]raclopride and PET in 18 previously untreated patients with Parkinson's disease (PD) and 14 healthy volunteer subjects. Sixteen patients were scanned before and after 3 to 4 months of stable oral therapy with either L-dopa (300 mg/d) (n = 7) or lisuride (0.8 to 1.2 mg/d) (n = 9). Two additional patients were investigated before and after a continuous IV infusion of L-dopa. In addition, we studied the effect of acute IV L-dopa and lisuride administration on [11C]raclopride binding in a healthy rhesus monkey. At baseline, PD patients showed higher uptake values in the putamen than did healthy subjects (p < 0.0001). Oral lisuride treatment lowered [11C]raclopride uptake in the putamen (-19%) and in the caudate nucleus (-15%) compared with baseline, but the difference did not reach significance upon Bonferroni correction for multiple comparisons. However, putamen tracer uptake returned to baseline in two patients when we repeated [11C]raclopride scans 4 days after lisuride withdrawal. Oral L-dopa treatment did not induce changes in the putamen or caudate nucleus indices. Acute lisuride (25 micrograms) administration in a healthy monkey reduced striatal uptake values, but acute injection of L-dopa (300 mg) did not. The results suggest that lisuride blocks [11C]raclopride binding at dopamine D2-receptor sites and demonstrate that 3 to 4 months' oral therapy with L-dopa or lisuride does not change striatal dopamine D2-receptor density in PD patients.

Atomically controlled quantum chains hosting a Tomonaga-Luttinger liquid

Abstract: The Tomonaga–Luttinger liquid model is the leading candidate for describing one-dimensional metallic conductors at low temperature. Yet, experimental evidence that it is valid is sketchy. Scanning tunnelling and photoemission spectra suggest that it does, in fact, describe the behaviour of chains of gold atoms self-assembled on the surface of germanium.