Construction and Test of a Gradient System for NMR Diffusion Studies in Interface Systems

Schlayer, Stefan; Stallmach, Frank; Horch, Carsten; Splith, Tobias; Pusch, Anne-Kristin; Pielenz, Frederike; Peksa, Mikuláš

doi:10.1002/cite.201300087

Cited by 8 publications

(6 citation statements)

References 28 publications

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“…Magnetic field gradient pulses in conventional PFG NMR can today be operated with values above 20 T/m. Schlayer et al [31], e.g., achieved a value of 37 T/m with a 100 A power supply. The design with two gradient coils on the top and on the bottom of the MAS stator of a Bruker probe reaches about 0.5 T/m with a 10 A power supply.…”

Section: Methodsmentioning

confidence: 99%

Diffusion in Nanoporous Materials: Novel Insights by Combining MAS and PFG NMR

2018

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Pulsed field gradient (PFG) nuclear magnetic resonance (NMR) allows recording of molecular diffusion paths (notably, the probability distribution of molecular displacements over typically micrometers, covered during an observation time of typically milliseconds) and has thus proven to serve as a most versatile means for the in-depth study of mass transfer in complex materials. This is particularly true with nanoporous host materials, where PFG NMR enabled the first direct measurement of intracrystalline diffusivities of guest molecules. Spatial resolution, i.e., the minimum diffusion path length experimentally observable, is limited by the time interval over which the pulsed field gradients may be applied. In “conventional” PFG NMR measurements, this time interval is determined by a characteristic quantity of the host-guest system under study, the so-called transverse nuclear magnetic relaxation time. This leads, notably when considering systems with low molecular mobilities, to severe restrictions in the applicability of PFG NMR. These restrictions may partially be released by performing PFG NMR measurements in combination with “magic-angle spinning” (MAS) of the NMR sample tube. The present review introduces the fundamentals of this technique and illustrates, via a number of recent cases, the gain in information thus attainable. Examples include diffusion measurements with nanoporous host-guest systems of low intrinsic mobility and selective diffusion measurement in multicomponent systems.

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Section: Methodsmentioning

confidence: 99%

Diffusion in Nanoporous Materials: Novel Insights by Combining MAS and PFG NMR

2018

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“…8 The self-diffusion coefficient D of water at a temperature of 303 K is D = 2.594 × 10 −9 m 2 s −1 . 49 The gradient strength obtained at 100% gradient intensity is 0.54 T m −1 for the MAS PFG NMR probe (AVANCE 750, 10 A gradient current supply) and 21 T m −1 for the static PFG NMR probe PK3 50 on AVANCE 400 (60 A gradient current supply). PK3 50 is a low-power homemade probe with a nutation frequency of 20 kHz for 1 H measurements.…”

Section: Methodsmentioning

confidence: 99%

“…The gradient strength obtained at 100% gradient intensity is 0.54 T m –1 for the MAS PFG NMR probe (AVANCE 750, 10 A gradient current supply) and 21 T m –1 for the static PFG NMR probe PK3 on AVANCE 400 (60 A gradient current supply). PK3 is a low-power homemade probe with a nutation frequency of 20 kHz for 1 H measurements. The repetition delay was always longer than the fivefold of the longitudinal relaxation time.…”

Section: Methodsmentioning

confidence: 99%

NMR Study of the Host Structure and Guest Dynamics Investigated with Alkane/Alkene Mixtures in Metal Organic Frameworks ZIF-8

et al. 2018

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Within the family of metal–organic frameworks, the zeolite–imidazolate framework (ZIF) of type ZIF-8 is among the most promising materials with potential application for hydrocarbon separation, notably of alkanes and alkenes. We have applied NMR spectroscopy for exploring the interaction of representative alkane/alkene mixtures with the host framework as well as the mobility of the various components in their mixture. Deviating from, for example, the separation patterns known for MFI-based membranes, the mobility of the faster molecules (alkenes) is found to remain essentially unaffected by the presence of more slowly diffusing molecules (alkanes). In addition, 2H and 67Zn magic-angle spinning NMR contributes to the characterization of ZIF-8 in search for guest-induced changes in the lattice structure.

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“…All NMR experiments were performed at 3T on a custom‐built 125 MHz FEGRIS‐NT spectrometer, which achieves a maximum gradient amplitude of

G_{italicmax}

= 35 T/m along the direction of the main magnetic field . The dimensions of the shielded gradient coil and the saddle‐type RF coil were optimized for a 10 mm sample height inside a 7 mm NMR tube . The sample temperature was controlled and monitored within

Δ T

= 0.1°C (0.1 K) using an evaporated nitrogen stream and a built‐in heater/thermometer regulation system.…”

Section: Methodsmentioning

confidence: 99%

“…55,56 The dimensions of the shielded gradient coil and the saddle-type RF coil were optimized for a 10 mm sample height inside a 7 mm NMR tube. 57 The sample temperature was controlled and monitored within ΔT = 0.1°C (0.1 K) using an evaporated nitrogen stream and a built-in heater/thermometer regulation system. The initial temperature was set to T = +20°C (293 K) and decreased to 0°C (273 K) in steps of 2°C (2 K).…”

Section: Nmr Acquisitionsmentioning

confidence: 99%

Influence of the extracellular matrix on water mobility in subcortical gray matter

Georgi

Metere

Jäger

et al. 2018

Magnetic Resonance in Med

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Purpose Water mobility in tissues is related to the microstructure that modulates diffusion and spin relaxation. Previous work has shown that the extracellular matrix (ECM) impacts water diffusion in cartilage. To investigate if similar contributions to image contrast exist for brain, which is characterized by a substantially lower ECM content, diffusion and relaxation were studied in fixed samples from goat and human thalamus before and after enzymatic digestion of ECM compounds. Selected experiments in human corpus callosum were included for comparing subcortical gray matter and white matter. Methods Digestion of matrix components was achieved by treatment with hyaluronidase. Nonlocalized pulsed field gradient measurements were performed with b values between 0.6 and 18,000 s/mm2 at 3T and temperatures between 0°C and 20°C, in addition to T1 and T2 relaxation measurements. The data were fitted to multiexponential models to account for different water compartments. After the measurements, the samples were sliced and stained for ECM‐sensitive markers to verify efficient digestion. Results Microstructural alterations associated with hyaluronan digestion did not lead to measurable effects on water diffusion or T2. However, T1 of the main relaxographic component, attributed to intra‐/extracellular water, decreased by 7%. Conclusion Investigations with very strong gradients did not reveal a detectable effect on water diffusion or T2 after hyaluronan removal, indicating that the brain ECM content is too low to produce a detectable effect. The subtle alteration of T1 upon hyaluronidase treatment might reflect a modulation of intercompartmental water exchange properties.

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Construction and Test of a Gradient System for NMR Diffusion Studies in Interface Systems

Cited by 8 publications

References 28 publications

Diffusion in Nanoporous Materials: Novel Insights by Combining MAS and PFG NMR

Diffusion in Nanoporous Materials: Novel Insights by Combining MAS and PFG NMR

NMR Study of the Host Structure and Guest Dynamics Investigated with Alkane/Alkene Mixtures in Metal Organic Frameworks ZIF-8

Influence of the extracellular matrix on water mobility in subcortical gray matter

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