Characterization of moisture in acetylated and propionylated radiata pine using low-field nuclear magnetic resonance (LFNMR) relaxometry

AbstractMoisture in radiata pine (Pinus radiataD. Don) earlywood (EW), which was acetylated or propionylated to various degrees, was measured by low-field nuclear magnetic resonance (LFNMR) relaxometry. Spin-spin relaxation times (T2) were determined for fully saturated samples at 22 and −18°C.T2values for EW lumen water increased with increasing acetylation weight percentage gain (WPG), perhaps caused by the less hydrophilic acetylated wood (AcW) surface. Cell wall water (WCW) and the water in pits and small voids also showed increasingT2values as a function of WPG but with a weaker tendency. A possible explanation is the counteracting effects of decreased hydrophilicity and reduced moisture content (MC) of these water populations at higher levels of acetylation. The evaluation of propionylation on WCWT2data was complicated by peak splitting in the relaxation spectrum. ConstantT2values for void water populations at various WPG levels for propionylated samples indicate a modification gradient in the cell wall. Fiber saturation point (FSP) was significantly reduced by both modifications. Slightly higher FSP values for propionylated samples suggest that physical bulking is not the only factor causing moisture exclusion in AcW. But this interpretation is tentative because of the possibility of cell wall damage caused by propionylation.

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Preliminary magnetic resonance relaxometric analysis of Fricke gel dosimeters produced with polyvinyl alcohol and glutaraldehyde

Nuclear Technology and Radiation Protection ◽

10.2298/ntrp1703242g ◽

2017 ◽

Vol 32 (3) ◽

pp. 242-249 ◽

Cited By ~ 9

Author(s):

Salvatore Gallo ◽

Giorgio Collura ◽

Giuseppina Iacoviello ◽

Anna Longo ◽

Luigi Tranchina ◽

...

Keyword(s):

Nuclear Magnetic Resonance ◽

Magnetic Resonance ◽

Polyvinyl Alcohol ◽

Dose Range ◽

Relaxation Times ◽

Ion Concentration ◽

Nuclear Magnetic Resonance Relaxometry ◽

New Formulation ◽

Nuclear Magnetic

This work describes the preliminary analysis of Fricke gels dosimeters characterized by a new formulation making use of a matrix of polyvinyl alcohol cross-linked by adding glutaraldehyde and analyzed by means of nuclear magnetic resonance relaxometry. In previous optical studies, these gels have shown promising dosimetric features in terms of photon sensitivity and low diffusion of ferric ions produced after irradiation. In this work, we used a portable nuclear magnetic resonance relaxometer to measure the relaxation times (which are important for dosimetric applications) of these gel materials. For this purpose, we performed a study for optimizing the acquisition parameters with a nuclear magnetic resonance relaxometer. Gel samples were exposed to clinical 6 MV photons in the dose range between 0 and 20 Gy. Nuclear magnetic resonance relaxometry measurements were per- formed and the sensitivity to photon beams was measured for various values of the Fe2+ ion concentration. The analyses pointed out that the MR signal increases as the Fe2+ content in- creases and the increase is about 75 % when the concentration of Fe2+ ions is increased from 0.5 mM to 2.5 mM. Furthermore, the sensitivity improvement achieved with increasing the Fe2+ concentration is about 60 %. This paper shows that the portable nuclear magnetic resonance relaxometer used for analysis of porous materials can be used for characterization of these dosimetric gels and this study can be considered as the first step for the characterization of these dosimeters which in future could be used for 3-D dose mapping in clinical applications.

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High-resolution characterization of nanoparticle transport in heterogeneous porous media via low-field nuclear magnetic resonance

Journal of Hydrology ◽

10.1016/j.jhydrol.2020.124558 ◽

2020 ◽

Vol 583 ◽

pp. 124558

Author(s):

Qian Zhang ◽

Yanhui Dong ◽

Hang Deng ◽

Derek Elsworth

Keyword(s):

Nuclear Magnetic Resonance ◽

Porous Media ◽

Magnetic Resonance ◽

High Resolution ◽

Heterogeneous Porous Media ◽

Nanoparticle Transport ◽

Low Field ◽

Nuclear Magnetic

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Nuclear Magnetic Resonance (NMR) Characterization of a Polymerized Ionic Liquid Electrolyte Material

MRS Proceedings ◽

10.1557/opl.2012.1280 ◽

2012 ◽

Vol 1440 ◽

Cited By ~ 3

Author(s):

A.L. Michan ◽

G.T.M. Nguyen ◽

O. Fichet ◽

F. Vidal ◽

C. Vancaeyzeele ◽

...

Keyword(s):

Nuclear Magnetic Resonance ◽

Magnetic Resonance ◽

Field Gradient ◽

Diffusion Coefficients ◽

Polymer Network ◽

Relaxation Times ◽

Solid Polymer ◽

Pulsed Field ◽

Nuclear Magnetic

ABSTRACTSolid electrolyte materials have the potential to improve performance and safety characteristics of lithium-ion batteries by replacing conventional solvent-based electrolytes. A candidate solid polymer electrolyte, AMLi/PEGDM, has been synthesized by crosslinking an anionic monomer AMLi, with poly(ethylene glycol) dimethacrylate. The main goal of the synthesis is to produce a single-ion conducting polymer network where lithium cations can move freely and fluorinated anions are immobilized as part of the polymer network. A comprehensive characterization of anion and cation mobility in the resulting material is therefore required. Using pulsed-field gradient nuclear magnetic resonance (PFG-NMR), we are able to measure and quantify the individual diffusion coefficients of mobile species in the material (19F and 7Li) and confirm the extent to which the fluorinated anionic component is immobilized. We have characterized dry (σ~3.0 x10-7 S/cm at 30°C) and propylene carbonate (PC) saturated gel (σ~1.0x10-4 S/cm at 30°C) samples. Experimental results include NMR spin-spin and spin-lattice relaxation times in addition to diffusion coefficient measurements over a temperature range up to 100°C. Practically, the diffusion measurements are extremely challenging, as the spin-spin (T2) relaxation times are very short, necessitating the development of specialized pulsed-field gradient apparatus. Diffusion coefficients for the most mobile components of the lithium cations and fluorinated anions at 100°C in dry membranes have been found to be 3.4 x10-8 cm2/s and 2.1 x10-8 cm2/s respectively. These results provide valuable insight into the conduction mechanisms in these materials, and will drive further optimization of solid polymer electrolytes.

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