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Aachen, Germany

Perlo J.,RWTH Aachen | Silletta E.V.,National University of Cordoba | Danieli E.,RWTH Aachen | Cattaneo G.,Acandis GmbH and Co. KG | And 3 more authors.
Magnetic Resonance Imaging | Year: 2015

In this work we evaluate the performance of a 40-mm diameter bore 0.2T desktop Halbach tomograph to obtain 2D and 3D velocity maps for studying intra-aneurismal flow in the presence or absence of nitinol meshed implants with the aim of optimizing the flow diverter efficacy. Phantoms with known spatial velocity distribution were used to determine the performance of the MRI system. Maximum velocities of about 200mm/s could be measured with a precision of 1% at a spatial resolution of 0.5×0.5×1mm3. This accuracy is suitable to evaluate in vitro intra-aneurismal flow under different conditions such as variable flow rates, different vessel-aneurysm geometry, as well as the influence of metallic flow diverters on the intra-aneurismal flow distribution. The information obtained non-invasively with desktop tomographs can be used to complement in vivo studies in order to decide the optimum flow diverter. © 2015 Elsevier Inc.

Danieli E.,RWTH Aachen | Perlo J.,Magritek GmbH | Duchateau A.L.L.,Royal DSM | Verzijl G.K.M.,Royal DSM | And 3 more authors.
ChemPhysChem | Year: 2014

Real-time nuclear magnetic resonance (NMR) spectroscopy measurements carried out with a bench-top system installed next to the reactor inside the fume hood of the chemistry laboratory are presented. To test the system for on-line monitoring, a transfer hydrogenation reaction was studied by continuously pumping the reaction mixture from the reactor to the magnet and back in a closed loop. In addition to improving the time resolution provided by standard sampling methods, the use of such a flow setup eliminates the need for sample preparation. Owing to the progress in terms of field homogeneity and sensitivity now available with compact NMR spectrometers, small molecules dissolved at concentrations on the order of 1 mmolL-1can be characterized in single-scan measurements with 1 Hz resolution. Owing to the reduced field strength of compact low-field systems compared to that of conventional high-field magnets, the overlap in the spectrum of different NMR signals is a typical situation. The data processing required to obtain concentrations in the presence of signal overlap are discussed in detail, methods such as plain integration and line-fitting approaches are compared, and the accuracy of each method is determined. The kinetic rates measured for different catalytic concentrations show good agreement with those obtained with gas chromatography as a reference analytical method. Finally, as the measurements are performed under continuous flow conditions, the experimental setup and the flow parameters are optimized to maximize time resolution and signal-to-noise ratio. © 2014 Wiley-VCH Verlag GmbH & Co. KGaA.

Goldbach M.,Royal DSM | Danieli E.,RWTH Aachen | Perlo J.,Magritek GmbH | Kaptein B.,Royal DSM | And 4 more authors.
Tetrahedron Letters | Year: 2016

A convenient method for the classical preparation of Grignard reagents from aryl halides and magnesium using a fluidized bed reactor under continuous flow conditions was developed. The process was combined with quenching of the Grignard reagent by CO2 as a model reaction performed using a second flow reactor. The formation and quenching of the reagent was monitored by on-line 1H NMR spectroscopy. The combination of continuous flow operation for Grignard reagents with reaction monitoring by on-line NMR spectroscopy allows one to quickly optimize the working conditions. © 2015 Elsevier Ltd.

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