Diffusion and flow in a porous structure by the gradient spin echo spectral analysis

Stepišnik, Janez; Mohorič, Aleš; Duh, Andrej

doi:10.1016/s0921-4526(01)01025-0

Cited by 27 publications

(31 citation statements)

References 21 publications

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“…o d can be exactly determined as the position of the main peak on the gradient modulation spectrum, which is the Fourier transform of the diffusion gradient first moment. 8,9 For apodized cosinemodulated gradients, practical relationship between the diffusion frequency and the effective diffusion time is given by t d ¼ 0.25/o d . 6 Magnetic Resonance Spectroscopy Methods Implementation…”

Section: Probing Diffusion Using Oscillating Gradientsmentioning

confidence: 99%

“…As a result, as the frequency decreases (long t d ), D does not tend towards zero but towards an effective diffusion coefficient D free /T 2 , where the tortuosity T reflects to what extent pores are interconnected. 9 Therefore, the term D free /T 2 is added to the sum in equation (5), and the resulting model has three free parameters: D free, T and d. Expressions of a k and B k for spherical pores are given by:…”

Section: Diffusion Modelsmentioning

confidence: 99%

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Anomalous Diffusion of Brain Metabolites Evidenced by Diffusion-Weighted Magnetic Resonance Spectroscopy in Vivo

Marchadour

Brouillet

Hantraye

et al. 2012

J Cereb Blood Flow Metab

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Translational displacement of molecules within cells is a key process in cellular biology. Molecular motion potentially depends on many factors, including active transport, cytosol viscosity and molecular crowding, tortuosity resulting from cytoskeleton and organelles, and restriction barriers. However, the relative contribution of these factors to molecular motion in the cytoplasm remains poorly understood. In this work, we designed an original diffusion-weighted magnetic resonance spectroscopy strategy to probe molecular motion at subcellular scales in vivo. This led to the first observation of anomalous diffusion, that is, dependence of the apparent diffusion coefficient (ADC) on the diffusion time, for endogenous intracellular metabolites in the brain. The observed increase of the ADC at short diffusion time yields evidence that metabolite motion is characteristic of hindered random diffusion rather than active transport, for time scales up to the dozen milliseconds. Armed with this knowledge, data modeling based on geometrically constrained diffusion was performed. Results suggest that metabolite diffusion occurs in a low-viscosity cytosol hindered by B2-mm structures, which is consistent with known intracellular organization.

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Section: Probing Diffusion Using Oscillating Gradientsmentioning

confidence: 99%

Section: Diffusion Modelsmentioning

confidence: 99%

Anomalous Diffusion of Brain Metabolites Evidenced by Diffusion-Weighted Magnetic Resonance Spectroscopy in Vivo

Marchadour

Brouillet

Hantraye

et al. 2012

J Cereb Blood Flow Metab

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“…In Fig.4A1, D(ω) shows a clear ω 2 -dependence at low frequencies, which is typical for restricted diffusion. In restricted diffusion case, the slope of D(ω) vs. is different from the Lorentzian spectrum for diffusion in porous media [14,29]. However, the length of ballistic grain motion depends on the distribution of adjacent beads, which might be responsible for the observed form of I z (ω) at high frequencies.…”

Section: Resultsmentioning

confidence: 91%

“…is introduced, which gives the low-frequency dependence similar to the restricted diffusion [29], and the exponential decay at high frequencies. Here ξ 2 is the size of the bead caging, τ c is the characteristic time of ballistic motion and D is the diffusion-like constant describing hopping between cages.…”

Section: Resultsmentioning

confidence: 99%

Autocorrelation spectra of an air-fluidized granular system measured by NMR

et al. 2006

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“…The MGSE approach is able to separate the effects of restricted diffusion from molecular migration across the interconnected porous structure. [31][32][33] This fact allows one to determine tortuosity as well as the size of restrictions experienced by the diffusing molecules. Different gradient modulation schemes have been employed in MGSE experiments to study water diffusion in porous media 32 and in emulsions.…”

mentioning

confidence: 99%

Investigations of vesicle gels by pulsed and modulated gradient NMR diffusion techniques

Lasič¹,

Åslund²,

Oppel³

et al. 2011

Soft Matter

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Vesicle gels are surfactant systems that form stiff gels with rather low amounts of surfactant. So far their structures have mostly been investigated using scattering techniques, which are generally appropriate for the study of structures on the nm-length-scale. Here we examine these gels using two complementary diffusion NMR techniques, which are both sensitive to structures on the mm-scale. The presented results imply structural features on the mm-scale, indicating a more complex structure than just that of densely packed small vesicles, as previously found for these systems. It is demonstrated that a combination of the diffusion NMR methods, described here, can provide useful insights, when morphological features extend over a wide range of length scales.

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Diffusion and flow in a porous structure by the gradient spin echo spectral analysis

Cited by 27 publications

References 21 publications

Anomalous Diffusion of Brain Metabolites Evidenced by Diffusion-Weighted Magnetic Resonance Spectroscopy in Vivo

Anomalous Diffusion of Brain Metabolites Evidenced by Diffusion-Weighted Magnetic Resonance Spectroscopy in Vivo

Autocorrelation spectra of an air-fluidized granular system measured by NMR

Investigations of vesicle gels by pulsed and modulated gradient NMR diffusion techniques

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