Pulse Gradient Spin Echo Measurement of Flow Dynamics in a Porous Structure: NMR Spectral Analysis of Motional Correlations

2002 ◽  
pp. 433-444
Author(s):  
Janez Stepišnik ◽  
Aleš Mohorič ◽  
Andrej Duh
Keyword(s):  
Spectral Analysis ◽  
Porous Structure ◽  
Spin Echo ◽  
Flow Dynamics ◽  
Pulse Gradient

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

2001 ◽  
Vol 307 (1-4) ◽  
pp. 158-168 ◽  
Author(s):  
Janez Stepišnik ◽  
Aleš Mohorič ◽  
Andrej Duh
Keyword(s):  
Spectral Analysis ◽  
Porous Structure ◽  
Spin Echo

scholarly journals Sequential Diffusion Spectra as a Tool for Studying Time-Dependent Translational Molecular Dynamics: A Cement Hydration Study

Molecules ◽  
2019 ◽  
Vol 25 (1) ◽  
pp. 68
Author(s):  
Igor Serša
Keyword(s):  
Molecular Dynamics ◽  
Porous Structure ◽  
Time Scales ◽  
Cement Hydration ◽  
Pulse Sequence ◽  
Spin Echo ◽  
Model Parameters ◽  
Signal Attenuation ◽  
Wide Range ◽  
Novel Method

The translational molecular dynamics in porous materials are affected by the presence of the porous structure that presents an obstacle for diffusing molecules in longer time scales, but not as much in shorter time scales. The characteristic time scales have equivalent frequency ranges of molecular dynamics, where longer time scales correspond to lower frequencies while the shorter time scales correspond to higher frequencies of molecular dynamics. In this study, a novel method for direct measurement of diffusion at a given frequency of translational molecular dynamics is exploited to measure the diffusion spectra, i.e., distribution of diffusion in a wide range of frequencies. This method utilizes NMR modulated gradient spin-echo (MGSE) pulse sequence to measure the signal attenuation during the train of spin-echoes formed in the presence of a constant gradient. From attenuation, the diffusion coefficient at the frequency equal to the inverse double inter-echo time is calculated. The method was employed to study the white cement hydration process by the sequential acquisition of the diffusion spectra. The measured spectra were also analyzed by the diffusion spectra model to obtain the time-dependence of the best-fit model parameters. The presented method can also be applied to study other similar systems with the time evolution of porous structure.

Do dendritic amphiphiles self-assemble in water? A Fourier transform pulse-gradient spin-echo NMR study

2001 ◽  
Vol 14 (7) ◽  
pp. 392-399 ◽  
Author(s):  
Fredric M. Menger ◽  
Andrey V. Peresypkin ◽  
Shaoxiong Wu
Keyword(s):  
Fourier Transform ◽  
Spin Echo ◽  
Nmr Study ◽  
Pulse Gradient

scholarly journals New Biocompatible Polyurethanes: Synthesis, Structural Characterization and Cytotoxicity

2018 ◽  
Author(s):  
Barbara S. Gregorí Valdes ◽  
Clara S. B. Gomes ◽  
Pedro T. Gomes ◽  
José R. Ascenso ◽  
Hermínio P. Diogo ◽  
...  
Keyword(s):  
13C Nmr ◽  
Spin Echo ◽  
Assay Method ◽  
Molecular Weights ◽  
Pulse Gradient ◽  
Diluted Solution ◽  
Keratinocyte Cell ◽  
Hacat Keratinocyte ◽  
Pgse Nmr ◽  
Poly Propylene

The synthesis of four samples of new polyurethanes was evaluated by changing the ratio of the diol monomers used, poly(propylene glycol) (PPG) and D-isosorbide, in the presence of aliphatic isocyanates such as the isophorone diisocyanate (IPDI) and 4,4′-methylenebis(cyclohexyl isocyanate) (HMDI). The thermal properties of the four polymers obtained were determined by DSC, exhibiting Tg values in the range 55-70 ºC, and their molecular structure characterized by FTIR, 1H and 13C NMR spectroscopies. The diffusion coefficients of these polymers in solution were measured by the Pulse Gradient Spin Echo (PGSE) NMR method, enabling the calculation of the corresponding hydrodynamic radii in diluted solution (1.62–2.65 nm). The molecular weights were determined by GPC/SEC and compared with the values determined by quantitative 13C NMR analysis. Finally, the biocompatibility of the polyurethanes was assessed using the HaCaT keratinocyte cell line by the MTT reduction assay method showing values superior to 70% cell viability.

A 1H NMR pulse gradient spin-echo (PGSE) study of the mass transport of dimethyl oxalate and ethylene glycol: new fuels for the DOFC

2003 ◽  
Vol 48 (14-16) ◽  
pp. 2187-2193 ◽  
Author(s):  
S. Suarez ◽  
S.H. Chung ◽  
S. Greenbaum ◽  
S. Bajue ◽  
E. Peled ◽  
...  
Keyword(s):  
Mass Transport ◽  
Ethylene Glycol ◽  
1H Nmr ◽  
Spin Echo ◽  
Dimethyl Oxalate ◽  
Pulse Gradient

scholarly journals Synthesis and Characterization of Isosorbide-Based Polyurethanes Exhibiting Low Cytotoxicity Towards HaCaT Human Skin Cells

Polymers ◽  
2018 ◽  
Vol 10 (10) ◽  
pp. 1170 ◽  
Author(s):  
Barbara Gregorí Valdés ◽  
Clara Gomes ◽  
Pedro Gomes ◽  
José Ascenso ◽  
Hermínio Diogo ◽  
...  
Keyword(s):  
13C Nmr ◽  
Spin Echo ◽  
Assay Method ◽  
Molecular Weights ◽  
Pulse Gradient ◽  
Diluted Solution ◽  
Keratinocyte Cell ◽  
Low Cytotoxicity ◽  
Hacat Keratinocyte ◽  
Pgse Nmr

The synthesis of four samples of new polyurethanes was evaluated by changing the ratio of the diol monomers used, poly(propylene glycol) (PPG) and D-isosorbide, in the presence of aliphatic isocyanates such as the isophorone diisocyanate (IPDI) and 4,4′-methylenebis(cyclohexyl isocyanate) (HMDI). The thermal properties of the four polymers obtained were determined by DSC, exhibiting Tg values in the range 55–70 °C, and their molecular structure characterized by FTIR, 1H, and 13C NMR spectroscopies. The diffusion coefficients of these polymers in solution were measured by the Pulse Gradient Spin Echo (PGSE) NMR method, enabling the calculation of the corresponding hydrodynamic radii in diluted solution (1.62–2.65 nm). The molecular weights were determined by GPC/SEC and compared with the values determined by a quantitative 13C NMR analysis. Finally, the biocompatibility of the polyurethanes was assessed using the HaCaT keratinocyte cell line by the MTT reduction assay method showing values superior to 70% cell viability.

Self-Diffusion in Compressed Dimethylether: The Influence of Dipole-Dipole Interaction and Hydrogen Bonding Upon Translational Diffusivity in Simple Fluids

1995 ◽  
Vol 50 (2-3) ◽  
pp. 145-148 ◽  
Author(s):  
A. Heinrich-Schramm ◽  
W. E. Price ◽  
H.-D. Lüdemann
Keyword(s):  
Hydrogen Bonding ◽  
Dipole Moment ◽  
Diffusion Coefficients ◽  
Spin Echo ◽  
Dipole Interaction ◽  
Gradient Field ◽  
Simple Fluids ◽  
Self Diffusion ◽  
Pulse Gradient ◽  
Calculated Activation

Abstract Self-diffusion coefficients of dimethylether have been measured as a function of temperature (185-458 K) and pressure (up to 200 MPa) by pulse-gradient field spin-echo NMR. Calculated activation volumes (ΔV*) fall from 15 (10-6 m3/mole) at the highest temperature to 7 (10-6 m3/mole) at the lowest. This trend is in keeping with values for other non-associating liquids. Comparison with self diffusion data for propane and ethanol reveals that the translational diffusivity in dimethylether is influenced by the substance's modest dipole moment (1.3 Debye). The effect is small but measur­able and becomes more pronounced at lower temperatures.

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