Solving Fredholm integrals of the first kind with tensor product structure in 2 and 2.5 dimensions

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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“…Via regularization and by the approach of Venkataramanan et al [35] and Song et al [36] this problem became solvable by conventional desktop PCs.…”

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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“…• La méthode employée dans (Butler et al, 1981;Venkataramanan et al, 2002;Lamanna, 2005) repose sur l'utilisation de la pénalisation de Tikhonov…”

Section: Méthodes D'inversion Pénalisée Existantesunclassified

OPTIMED : optimisation itérative pour la résolution de problèmes inverses de grande taille

Chaâri¹,

Chouzenoux²,

Pustelnik³

et al. 2011

Traitement du signal

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“…Small and big delta were 1 ms and 10 ms, respectively. Two-dimensional T 1 -T 2 and T 2 -D correlation was analyzed by 2D ILT -two-dimensional numerical inverse Laplace transformation [42][43][44].…”

Section: Swelling Kinetics At 5°c 19°c and 30°c By 1 H Nmr Measurementsmentioning

confidence: 99%

Proton NMR Relaxometry as a Useful Tool to Evaluate Swelling Processes in Peat Soils~!2009-07-26~!2009-12-04~!2010-06-15~!

Jaeger¹,

Shchegolikhina²,

As³

et al. 2010

TOMRJ

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Dramatic physical and physico-chemical changes in soil properties may arise due to temperature and moisture variations as well as swelling of soil organic matter (SOM) under constant conditions. Soil property variations may influence sorption/desorption and transport processes of environmental contaminants and nutrients in natural-organic-matterrich soils. Notwithstanding the studies reported in literature, a mechanistic model for SOM swelling is unavailable yet. The objective of the present study was the evaluation of the swelling of peat soils, considered as SOM models, by 1 H NMR relaxometry and differential scanning calorimetry (DSC). Namely, information on the processes governing physical and physicochemical changes of peat during re-hydration were collected. The basic hypothesis of the present study was that the changes are slow and may affect water state as well as amounts of different water types into the peats. For this reason, such changes can be evidenced through the variations of mobility and thermal behaviour of the involved H 2 O molecules by using 1 H NMR relaxometry and DSC. According to the experimental results, a mechanistic model, describing the fundamental processes of peat swelling, was obtained. Two different peats re-wetted at three temperatures were used. The swelling process was monitored by measuring spin-spin relaxation time (T2) over a hydration time of several months. Moreover, DSC, T1 -T2 and T2 -D correlation measurements were done at the beginning and at the end of the hydration. Supplementary investigations were also done in order to discriminate between the swelling effects and the contributions from soil solution, internal magnetic field gradients and/or soil microorganisms to proton relaxation. All the results revealed peat swelling. It was evidenced by pore size distribution changes, volumetric expansion and redistribution of water, increasing amounts of nonfreezable and loosely bound water, as well as formation of gel phases and reduction of the translational and rotational mobility of H 2 O molecules. All the findings implied that changes of the physical and physicochemical properties of peats were obtained. In particular, three different processes having activation energies comprised in the interval 5 -50 kJ mol -1 were revealed. The mechanistic model which was, then, developed included water reorientation in bound water phases, water diffusion into the peat matrix and reorientation of SOM chains as fundamental processes governing SOM swelling. This study is of environmental significance in terms of re-naturation and re-watering of commercially applied peatlands and of sorption/desorption and transport processes of pollutants and nutrients in natural organic matter rich soils.

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Solving Fredholm integrals of the first kind with tensor product structure in 2 and 2.5 dimensions

Cited by 595 publications

References 15 publications

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

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

OPTIMED : optimisation itérative pour la résolution de problèmes inverses de grande taille

Proton NMR Relaxometry as a Useful Tool to Evaluate Swelling Processes in Peat Soils~!2009-07-26~!2009-12-04~!2010-06-15~!

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