NMR Study of Miscibility in Polyepichlorohydrin/Poly(Vinylmethylether) Blends

1994 ◽  
Vol 67 (4) ◽  
pp. 629-635 ◽  
Author(s):  
K. J. McGrath ◽  
C. M. Roland
Keyword(s):  
Glass Transition ◽  
Nmr Spectroscopy ◽  
Chemical Shift ◽  
Glass Transition Temperatures ◽  
129Xe Nmr ◽  
Nmr Study ◽  
Miscible Blends ◽  
Fast Exchange ◽  
Exchange Regime ◽  
Fast Exchange Regime

Abstract 129Xe NMR spectroscopy is employed to demonstrate that polyepichlorohydrin and poly(vinylmethylether), which have virtually equal glass transition temperatures, form thermodynamically miscible blends. This conclusion is drawn from the appearance of a single resonance in the blend spectrum, at a chemical shift differing from that calculated for the fast exchange regime. 13C NMR results are consistent with thermodynamic miscibility, and reflect the similarity of the component dynamics.

Intermolecular Interactions of Xe Atoms Confined in One-dimensional Nanochannels of Tris(o-phenylenedioxy)cyclotriphosphazene as Studied by High-pressure 129Xe NMR

2003 ◽  
Vol 58 (12) ◽  
pp. 727-734 ◽  
Author(s):  
Hirokazu Kobayashi ◽  
Takahiro Ueda ◽  
Keisuke Miyakubo ◽  
Taro Eguchi
Keyword(s):  
High Pressure ◽  
Nmr Spectroscopy ◽  
Chemical Shift ◽  
Pressure Dependence ◽  
Average Distance ◽  
Chemical Shift Tensor ◽  
Axially Symmetric ◽  
One Dimensional ◽  
129Xe Nmr ◽  
The One

The pressure dependence of the 129Xe chemical shift tensor confined in the Tris(o-phenylenedioxy) cyclotriphosphazene (TPP) nanochannel was investigated by high-pressure 129Xe NMR spectroscopy. The observed 129Xe spectrum in the one-dimensional TPP nanochannel (0.45 nm in diameter) exhibits a powder pattern broadened by an axially symmetric chemical shift tensor. As the pressure increases from 0.02 to 7.0 MPa, a deshielding of 90 ppm is observed for the perpendicularcomponent of the chemical shift tensor δ⊥, whereas a deshielding of about 30 ppm is observed for the parallel one, δ‖. This suggests that the components of the chemical shift tensor, δ‖ and δ⊥, are mainly dominated by the Xe-wall and Xe-Xe interaction, respectively. Furthermore, the effect of helium, which is present along with xenon gas, on the 129Xe chemical shift is examined in detail. The average distance between the Xe atoms in the nanochannel is estimated to be 0.54 nm. This was found by using δ⊥ at the saturated pressure of xenon, and comparing the increment of the chemicalshift value in δ⊥ to that of a β -phenol/Xe compound.

scholarly journals The impact of defects and crystal size on negative gas adsorption in DUT-49 analyzed by in situ 129Xe NMR spectroscopy.

2020 ◽  
Author(s):  
Simon Krause ◽  
Florian Reuter ◽  
Sebastian Ehrling ◽  
Volodymyr Bon ◽  
Irena Senkovska ◽  
...  
Keyword(s):  
Nmr Spectroscopy ◽  
Chemical Shift ◽  
Crystal Size ◽  
Gas Adsorption ◽  
Adsorption Behavior ◽  
129Xe Nmr ◽  
High Concentrations ◽  
The Impact ◽  
Fluid Interactions

The origin of crystal size-dependent adsorption behavior of flexible metal-organic frameworks is increasingly studied. In this contribution, we probe the solid-fluid interactions of DUT-49 crystals of different size by in situ 129Xe NMR spectroscopy at 200 K. With decreasing size of the crystals, the average solid-fluid interactions are found to decrease reflected by a decrease in chemical shift of adsorbed xenon from 230 to 200 ppm explaining the lack of adsorption-induced transitions for smaller crystals. However, recent studies propose that these results can also originate from the presence of lattice defects. To investigate the influence of defects on the adsorption behavior of DUT-49 we synthesized a series of samples with tailored defect concentrations and characterized them by in situ 129Xe NMR. In comparison to the results obtained for crystals with different size we find pronounced changes of the adsorption behavior and influence of the chemical shift only for very high concentrations of defects, which further emphasizes the important role of particle size phenomena.

A 139La NMR study of the interactions between the La(III) cation and D-ribose in aqueous solution

1994 ◽  
Vol 72 (7) ◽  
pp. 1753-1757 ◽  
Author(s):  
Zhigang Chen ◽  
Nicole Morel-Desrosiers ◽  
Jean-Pierre Morel ◽  
Christian Detellier
Keyword(s):  
Aqueous Solution ◽  
Nmr Spectroscopy ◽  
Chemical Shift ◽  
Stability Constant ◽  
Chemical Shifts ◽  
Similar Treatment ◽  
Calorimetric Measurements ◽  
Nmr Study ◽  
The Stability ◽  
Good Agreement

The interactions of the La(III) cation with D-ribose and with D-arabinose in aqueous solution were investigated by 139La NMR spectroscopy. In the case of D-ribose, the formation of a La(III)-sugar complex was indicated by variations of the 139La chemical shift and linewidth with an increase of the sugar concentration in solution. In contrast, the complexation of La(III) by arabinose is very weak and almost undetectable by 139La NMR. On the basis of a 1:1 stoichiometry, the stability constant for the complex of La(III) with D-ribose was calculated from the observed 139La chemical shift values. A similar treatment was done for the viscosity corrected 139La linewidths using arabinose as an uninteractive reference. The stability constants, K, obtained independently from 139La chemical shifts and linewidths are in good agreement, 2.8 ± 0.5 and 2.2 ± 0.6 M−1 respectively at 299.0 ± 0.5 K. The thermodynamic parameters for the complexation of La(III) by D-ribose could also be obtained: ΔH0 = −12 ± 2 kJ mol−1, and ΔS0 = −31 ± 5 J K−1 mol−1. These values are in very good agreement with those obtained by calorimetric measurements.

scholarly journals A high-resolution natural abundance 33S MAS NMR study of the cementitious mineral ettringite

2017 ◽  
Vol 19 (35) ◽  
pp. 24082-24089 ◽  
Author(s):  
Akiko Sasaki ◽  
Luis Baquerizo Ibarra ◽  
Stephen Wimperis
Keyword(s):  
Nmr Spectroscopy ◽  
High Resolution ◽  
Chemical Shift ◽  
Mas Nmr ◽  
Natural Abundance ◽  
Nmr Study

Natural abundance 33S STMAS NMR spectroscopy is used to determine the 33S chemical shift and quadrupolar parameters in the cement-forming mineral ettringite.

scholarly journals Nongaussian Intravoxel Incoherent Motion Diffusion Weighted and Fast Exchange Regime Dynamic Contrast-Enhanced-MRI of Nasopharyngeal Carcinoma: Preliminary Study for Predicting Locoregional Failure

Cancers ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 1128
Author(s):  
Ramesh Paudyal ◽  
Linda Chen ◽  
Jung Hun Oh ◽  
Kaveh Zakeri ◽  
Vaios Hatzoglou ◽  
...  
Keyword(s):  
Nasopharyngeal Carcinoma ◽  
Intravoxel Incoherent Motion ◽  
Cutoff Value ◽  
Dce Mri ◽  
Locoregional Failure ◽  
Dynamic Contrast Enhanced ◽  
Contrast Enhanced ◽  
Fast Exchange ◽  
Exchange Regime ◽  
Fast Exchange Regime

The aim of the present study was to identify whether the quantitative metrics from pre-treatment (TX) non-Gaussian intravoxel incoherent motion (NGIVIM) diffusion weighted (DW-) and fast exchange regime (FXR) dynamic contrast enhanced (DCE)-MRI can predict patients with locoregional failure (LRF) in nasopharyngeal carcinoma (NPC). Twenty-nine NPC patients underwent pre-TX DW- and DCE-MRI on a 3T MR scanner. DW imaging data from primary tumors were fitted to monoexponential (ADC) and NGIVIM (D, D*, f, and K) models. The metrics Ktrans, ve, and τi were estimated using the FXR model. Cumulative incidence (CI) analysis and Fine-Gray (FG) modeling were performed considering death as a competing risk. Mean ve values were significantly different between patients with and without LRF (p = 0.03). Mean f values showed a trend towards the difference between the groups (p = 0.08). Histograms exhibited inter primary tumor heterogeneity. The CI curves showed significant differences for the dichotomized cutoff value of ADC ≤ 0.68 × 10−3 (mm2/s), D ≤ 0.74 × 10−3 (mm2/s), and f ≤ 0.18 (p < 0.05). τi ≤ 0.89 (s) cutoff value showed borderline significance (p = 0.098). FG’s modeling showed a significant difference for the K cutoff value of ≤0.86 (p = 0.034). Results suggest that the role of pre-TX NGIVIM DW- and FXR DCE-MRI-derived metrics for predicting LRF in NPC than alone.

scholarly journals The impact of defects and crystal size on negative gas adsorption in DUT-49 analyzed by in situ 129Xe NMR spectroscopy.

2020 ◽  
Author(s):  
Simon Krause ◽  
Florian Reuter ◽  
Sebastian Ehrling ◽  
Volodymyr Bon ◽  
Irena Senkovska ◽  
...  
Keyword(s):  
Nmr Spectroscopy ◽  
Chemical Shift ◽  
Crystal Size ◽  
Gas Adsorption ◽  
Adsorption Behavior ◽  
129Xe Nmr ◽  
High Concentrations ◽  
The Impact ◽  
Fluid Interactions

The origin of crystal size-dependent adsorption behavior of flexible metal-organic frameworks is increasingly studied. In this contribution, we probe the solid-fluid interactions of DUT-49 crystals of different size by in situ 129Xe NMR spectroscopy at 200 K. With decreasing size of the crystals, the average solid-fluid interactions are found to decrease reflected by a decrease in chemical shift of adsorbed xenon from 230 to 200 ppm explaining the lack of adsorption-induced transitions for smaller crystals. However, recent studies propose that these results can also originate from the presence of lattice defects. To investigate the influence of defects on the adsorption behavior of DUT-49 we synthesized a series of samples with tailored defect concentrations and characterized them by in situ 129Xe NMR. In comparison to the results obtained for crystals with different size we find pronounced changes of the adsorption behavior and influence of the chemical shift only for very high concentrations of defects, which further emphasizes the important role of particle size phenomena.

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