An NMR technique for rapid measurement of flow

Song, Yi‐Qiao; Scheven, Ulrich M.

doi:10.1016/j.jmr.2004.09.018

Cited by 29 publications

(31 citation statements)

References 10 publications

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“…The inclusion of the Dirac delta function in the correction, Eq. [16], prevents the third moment from reaching zero even at very long times or large displacements.…”

Section: Flow Propagatorsmentioning

confidence: 99%

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Rapid measurements of diffusion using PFG: Developments and applications of the Difftrain pulse sequence

Mitchell

Johns

2009

Concepts Magnetic Resonance

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Pulsed-field gradient (PFG) nuclear magnetic resonance (NMR) is one of the few experimental techniques that can determine directly mean square molecular displacements, allowing self-diffusion coefficient of liquids to be derived. PFG measurements are used commonly for diffusion, flow, and microstructure characterization. However, these conventional PFG experiments are often time consuming, requiring the gradient strength or observation time to be incremented independently. Here we discuss how the rapid Difftrain pulse sequence has proved invaluable in the study of time sensitive systems by allowing multiple observation times to be probed in a single scan. Difftrain has been applied successfully to the study of emulsions, surfactant solutions, bead packs, and permeable rock cores. We discuss various implementations of the Difftrain pulse sequence, suggest suitable phase cycles, and review the applications to date.

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“…The inclusion of the Dirac delta function in the correction, Eq. [16], prevents the third moment from reaching zero even at very long times or large displacements.…”

Section: Flow Propagatorsmentioning

confidence: 99%

“…There are several other rapid diffusion measurement techniques described in the literature (14)(15)(16)(17)(18)(19)(20)(21) although Difftrain offers uniquely the user the ability to predetermine, unambiguously, the values of observation time and gradient strength.…”

Section: Introductionmentioning

confidence: 99%

Rapid measurements of diffusion using PFG: Developments and applications of the Difftrain pulse sequence

Mitchell

Johns

2009

Concepts Magnetic Resonance

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“…qðtÞg v ðtÞtdt: [22] Note also that this term can be conveniently related to the coherence pathway wavevector k v along the velocity through integration of Eq. [22] by parts:…”

Section: D Flowmentioning

confidence: 99%

Multiple‐modulation‐multiple‐echo magnetic resonance

Sigmund

Cho

Song

2007

Concepts Magnetic Resonance

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ABSTRACT:We describe several applications of a versatile pulse sequence family employing multiple spin echoes within one acquisition to accelerate multidimensional experiments. The core sequence, called multiple modulation multiple echo, measures the maximal set of spin echoes generated from a set of RF pulses with unequal time spacings. These echoes can be modulated individually to exhibit different encoding. As a result, one scan of the sequence determines a series of data points as a function of the specific encoding mechanism. The variety of realizations of this sequence includes single shot measurements of diffusion or flow in 1D, 2D, and single-scan 2D slice-selective imaging. The essential spin dynamics of such sequences is introduced and their applications are reviewed.

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“…Multiple gradient methods provide the ability to determine multiple displacement directional correlations [16,57], velocity time and directional correlations [58], frequency dependent dispersion [59] and velocity autocorrelation functions [60,61]. In addition rapid 'single shot' techniques for the measurement of effective diffusion and flow provide the means to acquire complete data in the millisecond time scale to study transient behavior [62,63]. Of particular application to the study of bioactivity in porous media are new techniques for the measurements of 2-D correlations of magnetic relaxation time and effective diffusion [64][65][66].…”

Section: Advanced Techniquesmentioning

confidence: 99%

Finla Technical Report DE-FG02-03ER63576

Seymour¹

2007

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The magnetic resonance microscopy (MRM) work at Montana State University has extended the imaging of a single biofilm in a 1 mm capillary reactor to correlate T 2 magnetic relaxation maps displaying biofilm structure with the corresponding velocity patterns in three dimensions in a Staphylococcus epidermidis biofilm fouled square capillary. A square duct geometry is chosen to provide correlation with existing experiments and simulations, as research bioreactors tend to be of square or rectangular cross section for optical or microelectrode access. The spatially resolved velocity data provide details on the impact of biofilm induced advection on mass transport from the bulk fluid to the biofilm and through the capillary bioreactor. These issues are of significant importance in biosensor and bioseparations applications based on microfluidics or 'lab on a chip' technology, as well as a model for a flow in fractured geological media. Extension of published work in Journal of Magnetic Resonance applied concepts from the theory of fluid mixing to quantify the secondary flows induced by the spatially heterogeneous biofilm. The secondary flows are measured to be 20% of the axial velocity and indicate a significant alteration of transport from the bulk fluid to the biomass from diffusive to convective dominated. A paper has been published in Biotechnology and Bioengineering detailing the experimental results and analysis. The impact of microbial activity, particularly surface attached biofilms, on the transport of fluids in porous systems is relevant to fields as seemingly diverse as geophysics and medicine. Few direct experimental data on the impact of bioactivity on transport dynamics in three-dimensional media are available due to sample opacity. Non-invasive magnetic resonance microscopy (MRM) directly measures length and time scale dependent dynamics in porous media. Our research demonstrates by direct measurement of the propagator, i.e. the displacement conditional probability or van Hove scattering function, the transition from normal to anomalous hydrodynamic dispersion as a function of bioactivity. The microbial activity transforms the porous media from a homogeneous to heterogeneous structure, increasing system complexity as defined in terms of dynamics. Continuous time random walk (CTRW) based fractional advection-diffusion equation (ADE) models which generate anomalous or fractional dynamics are compared to the measured dynamics in both the propagator displacement space and the Fourier reciprocal displacement wavelength space. The data provide insight into the application and development of fractional calculus based models and indicates their direct applicability to biofilm impacted porous media transport. A manuscript reporting these results was published in Physical Review Letters. Unsaturated flow in porous media has been analyzed using magnetic resonance (MR) propagator measurements of scale dependent displacement. The data show a change in dynamics from Gaussian to non-Gaussian. Velocity and pore distrib...

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An NMR technique for rapid measurement of flow

Cited by 29 publications

References 10 publications

Rapid measurements of diffusion using PFG: Developments and applications of the Difftrain pulse sequence

Rapid measurements of diffusion using PFG: Developments and applications of the Difftrain pulse sequence

Multiple‐modulation‐multiple‐echo magnetic resonance

Finla Technical Report DE-FG02-03ER63576

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