Diffusion–relaxation correlation in simple pore structures

Callaghan, Paul T.; Godefroy, S.; Ryland, Brett N.

doi:10.1016/s1090-7807(03)00056-9

Cited by 73 publications

(54 citation statements)

References 22 publications

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“…• Measurement of translational diffusion of the confined water using pulsed magnetic field gradient or fringe magnetic field gradient techniques (Mitzithras et al, 1992;Codd and Callaghan, 1999;Stallmach and Kärger, 1999;Paoli et al, 2002;Kimmich, 2002;Callaghan et al, 2003;Valiullin et al, 2003;Geier et al, 2004).…”

Section: Nmr Relaxation Diffusion and Cryoporometry Studiesmentioning

confidence: 99%

Structural and dynamic studies of water in mesoporous silicas using neutron scattering and nuclear magnetic resonance

Webber

Dore

2004

J. Phys.: Condens. Matter

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Abstract. Experimental techniques for studying the behaviour of water in confined geometry using neutron scattering and NMR methods are reviewed. A brief survey is given of earlier work on sol-gel silicas and these findings are updated by reference to current work on MCM-and SBA-type silicas. Particular attention is focused on the phase transitions and the relation between super-cooled water and ice phases in the confined geometry of the mesopores. The characteristics are found to behave in a systematic manner although the nucleation phenomena for partially-filled pores reveals some unexpected complexity for the SBA-silicas.

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Section: Nmr Relaxation Diffusion and Cryoporometry Studiesmentioning

confidence: 99%

Structural and dynamic studies of water in mesoporous silicas using neutron scattering and nuclear magnetic resonance

Webber

Dore

2004

J. Phys.: Condens. Matter

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“…The aim of this contribution is to investigate the concentration and temperature dependence of self-diffusion of benzene in MOF-5 by the PFG NMR spin echo technique [22] and by diffusion-relaxation correlation spectroscopy (DRCOSY) [24,25]. In recent work, we found an agreement between the results of PFG NMR [26] and MD simulations [13] at 298 K at a relatively low loading of six benzene molecules per unit cell of MOF-5.…”

Section: Introductionmentioning

confidence: 66%

“…In order to gain information about correlations between diffusivities and T 2 relaxation times, one may apply the so called diffusion relaxation correlation spectroscopy (DR-COSY) pulse sequence [24,25]. Figure 4 shows a typical DRCOSY pulse sequence.…”

Section: The Drcosy Pulse Sequencementioning

confidence: 99%

NMR studies of benzene mobility in metal-organic framework MOF-5

Hertel

Wehring

Amirjalayer

et al. 2011

Eur. Phys. J. Appl. Phys.

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Abstract. The concentration and temperature dependence of the self-diffusion of benzene adsorbed in the metal-organic framework MOF-5 (IRMOF-1) is studied by pulsed field gradient (PFG) NMR spectroscopy.When increasing the loading from 10 to 20 molecules per unit cell of MOF-5, the experimental diffusion data drop by a factor of about three while current molecular dynamic (MD) simulations predict slightly increasing diffusion coefficients for this range of loadings. The observation is rationalized using the recently predicted clustering of adsorbate molecules in microporous systems for temperatures well below the adsorbate critical temperature. Necessary improvements of molecular simulation models for predicting diffusivities under such conditions are discussed.

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“…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]. These 2D MR parameter correlation methods provide the potential for unique data on the relation between the structure of the biofilm and the transport processes.…”

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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Diffusion–relaxation correlation in simple pore structures

Cited by 73 publications

References 22 publications

Structural and dynamic studies of water in mesoporous silicas using neutron scattering and nuclear magnetic resonance

Structural and dynamic studies of water in mesoporous silicas using neutron scattering and nuclear magnetic resonance

NMR studies of benzene mobility in metal-organic framework MOF-5

Finla Technical Report DE-FG02-03ER63576

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