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Item type:Publication, Access status: without files , Single-shot velocity mapping by rewinding of velocity encoding with Echo-Planar ImagingThe ability of single-shot NMR imaging methods to follow the time evolution of a velocity distribution within an object is strongly limited by the phase errors accumulated as velocity maps are acquired. In the particular case of Carr-Purcell based sequences combined with Echo Planar Imaging acquisition, phase accumulates through subsequent images, hampering the possibility to acquire several velocity maps, which would be useful to determine transient behavior. In this work, we propose the use of a rewinding velocity encoding module applied after the acquisition of each image during the CPMG echo train. In this way, the first velocity module imparts a velocity dependent phase prior to the image acquisition and the second pair cancels this phase out before the next refocusing radiofrequency pulse is applied. The performance and limits of this method are studied by acquiring 100 images of a co-rotating Couette cell over a period of 1.6 s as a function of the rotation speed. The method is applied to determine the kinematic viscosity of a water/alcohol mixture, which is a relevant topic in many physical, chemical and biological processes.Publicationtype: Journal ArticleScopus© Citations 3 34 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Magnetic Resonance Imaging in Situ Visualization of an Electrochemical Reaction under Forced Hydrodynamic Conditions(American Chemical Society (ACS), 2018); ; ; ; Magnetic resonance imaging (MRI) has proven to be a powerful tool for the characterization and investigation of in situ chemical reactions. This is more relevant when dealing with complex systems, where the spatial distribution of the species, partition equilibrium, flow patterns, among other factors have a determining effect over mass transport and therefore over the reaction rate. The advantage of MRI is that it provides spatial information in a noninvasive way and does not require any molecular sensor or sample extraction. In this work, MRI is used to fully characterize an electrochemical reaction under forced hydrodynamic conditions. Reaction rates, flow patterns, and quantitative concentration of the chemical species involved are spatially monitored in situ in a complex system that involves metallic pieces and a heterogeneous cementation reaction. Experimental data are compared with numerical simulations.Publicationtype: Journal Article47 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Flow-Pattern Characterization of Biphasic Electrochemical Cells by Magnetic Resonance Imaging under Forced Hydrodynamic ConditionsThe fluid dynamics of a liquid|liquid system inside a four-electrode electrochemical cell were studied by velocimetry magnetic resonance imaging (MRI) and flow propagator measurements. To characterize this system fully, three different cell configurations operating at two rotational frequencies were analyzed. Quantitative information about the stability of the liquid|liquid interface and the dynamics of the organic phase were determined. The NMR spectroscopy results were in agreement with the electrochemical measurements performed by using the same experimental setup.Publicationtype: Journal Article33 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Facilitated proton transfer across liquid | liquid interfaces under forced hydrodynamic conditions. Determination of partition coefficients of neutral weak basesA novel quantitative methodology to determine the partition coefficients of neutral weak bases is developed. This new electrochemical approach is based on the measurement of the total transferred charge across the oil | water interface under forced hydrodynamic conditions. The complete procedure has been validated by computational simulations and experimental results (Tylosin A). In addition, flow pattern caused inside the electrochemical cell was simulated with computational fluid dynamics using finite element methods and correlated with experimental results obtained by magnetic resonance imaging.Publicationtype: Journal Article35