Interfacial Spin–Spin Coupling in Wood by 2D Time-Domain NMR

Oleskevich, D.A.; Ghahramany, N.; Węglarz, Władysław P.; Peemoeller, H.

doi:10.1006/jmrb.1996.0148

Cited by 15 publications

(20 citation statements)

References 8 publications

(11 reference statements)

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“…As a result of exchange, which partially mixes magnetizations from different polymer regions on a timescale of hundreds of milliseconds, only the apparent values of T 1 and fraction magnitudes are observed. 46,47 The fact that at least two components are observed at all temperatures, in contrast to previous reports, 11,12 is likely due to extensive annealing of this sample, resulting in more effective separation between different regions in the sample.…”

Section: Present Resultscontrasting

confidence: 49%

Characterization of annealed isotactic polypropylene in the solid state by 2D time-domain1H NMR

Węglarz

Peemoeller

Rudin

2000

J. Polym. Sci. B Polym. Phys.

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Section: Present Resultscontrasting

confidence: 49%

Characterization of annealed isotactic polypropylene in the solid state by 2D time-domain1H NMR

Węglarz

Peemoeller

Rudin

2000

J. Polym. Sci. B Polym. Phys.

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“…(0), with the T 2 values and normalized magnetization fractions, obtained from the fit, given in Table. It may be noted that the T 2 values obtained from the present fit of the Gaussian damped sinc function or sinc-Gaussian function (∼ 20 µs) (Eq. (0)) are longer than those observed for the Gaussian fit for biological dry matrices (∼ 14 µs) [8].…”

Section: Resultsmentioning

confidence: 72%

“…The experimental parameters, and model apparent parameters calculated from Eq. (3) for certain trial intrinsic values of these parameters are compared within an iterative minimization algorithm, giving the intrinsic relaxation parameters ((1/T 1,int ) i [j] and k ij ), which represent the best match between these two sets of parameters [8]. We found the exchange rate k starch−water = 86 s −1 , and spin-lattice relaxation time T 1starch = 172 ms for the major 82.2% component, and T 1water = 49 ms for the minor 17.8% component magnetization.…”

Section: Resultsmentioning

confidence: 99%

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Investigation of Starch Hydration by 2D Time Domain NMR

et al. 2006

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Proton exchange between spin groups of the solid matrix of hydrated granular potato starch and water was studied using the 2D time domain NMR. The proton spin-spin relaxation time T2, and spin-lattice relaxation time T 1 (selective and non-selective pulse sequences) were measured at room temperature. The observed spin relaxation results were analysed for exchange assuming a two-site exchange model (between water and solid matrix of starch). In this analysis we determined the intrinsic spin-lattice relaxation time for water protons (49 ms) and solid starch matrix protons (172 ms), as well as the water-starch magnetization exchange rate (86 s −1 ).

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“…We obtained T ex = 8.1 ms which was in the same order as previous measurements for water in aspen wood (16 ms) [48], in poly [2-hydroxyethyl-methacrylaye] (21.1 ms) [12], in polyelectrolyte multilayers (24.6 ms) [37] and in filter paper (44 ms) [4].…”

Section: Goldman-shen Experimentsmentioning

confidence: 92%

Suppressing magnetization exchange effects in stimulated-echo diffusion experiments

Pagès

Dvinskikh

Furó

2013

Journal of Magnetic Resonance

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Exchange of nuclear magnetization between spin pools, either by chemical exchange or by cross-relaxation or both, has a significant influence on the signal attenuation in stimulated-echo-type pulsed field gradient experiments. Hence, in such cases the obtained molecular self-diffusion coefficients can carry a large systematic error. We propose a modified stimulated echo pulse sequence that contains T2-filters during the z-magnetization store period. We demonstrate, using a common theoretical description for chemical exchange and cross-relaxation, that these filters suppress the effects of exchange on the diffusional decay in that frequent case where one of the participating spin pools is immobile and exhibits a short T2. We demonstrate the performance of this experiment in an agarose/water gel. We posit that this new experiment has advantages over other approaches hitherto used, such as that consisting of measuring separately the magnetization exchange rate, if suitable by Goldman-Shen type experiments, and then correcting for exchange effects within the framework of a two-site exchange model. We also propose experiments based on selective decoupling and applicable in systems with no large T2 difference between the different spin pools.

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Interfacial Spin–Spin Coupling in Wood by 2D Time-Domain NMR

Cited by 15 publications

References 8 publications

Characterization of annealed isotactic polypropylene in the solid state by 2D time-domain1H NMR

Characterization of annealed isotactic polypropylene in the solid state by 2D time-domain1H NMR

Investigation of Starch Hydration by 2D Time Domain NMR

Suppressing magnetization exchange effects in stimulated-echo diffusion experiments

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