Methods

Cleaning oil paintings: NMR relaxometry and SPME to evaluate the effects of green solvents and innovative green gels

Gels have been recently introduced in conservation to better control the cleaning action. The slow solvent release is of the utmost importance to selectively remove varnish layers of few microns thickness, applied on painting layers which may have similar chemical properties. To evaluate the interactions of the underlying painting with solvents, diagnostic methods should study …

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Sequence for simultaneous measurement of long-limit diffusion and longitudinal relaxation in unilateral NMR

When unilateral NMR is employed with large gradients (20 T/m), measurements of T1 using standard sequences become affected by Brownian motion of spins, particularly in samples with long spin-lattice relaxation times T1 (>2000 ms) and a large diffusion coefficient D (2*10−6 mm2/ms). In light of this, a modified saturation sequence which we have called GAUSS-SR is proposed that allows direct measurement of both D and T1 to be …

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Probing molecular dynamics with hyperpolarized ultrafast Laplace NMR using a low-field, single-sided magnet

Laplace NMR (LNMR) offers deep insights on diffusional and rotational motion of molecules. The so-called “ultrafast” approach, based on spatial data encoding, enables one to carry out a multidimensional LNMR experiment in a single scan, providing from 10 to 1000-fold acceleration of the experiment. Here, we demonstrate the feasibility of ultrafast diffusion–T2 relaxation correlation (D–T2) measurements …

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Hydraulic characterisation of iron-oxide-coated sand and gravel based on nuclear magnetic resonance relaxation mode analyses

The capability of nuclear magnetic resonance (NMR) relaxometry to characterise hydraulic properties of iron-oxide-coated sand and gravel was evaluated in a laboratory study. Past studies have shown that the presence of paramagnetic iron oxides and large pores in coarse sand and gravel disturbs the otherwise linear relationship between relaxation time and pore size. Consequently, the …

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Visualizing the detection area of a unilateral NMR sensor using deconvolution and back-projection

Understanding the detection volume of a unilateral NMR sensor is crucial to interpret acquired data appropriately. Whereas this is easily done in the sensor’s axial dimension by running a depth profile on a well-defined sample, the lateral dimension is commonly characterized with very small samples, where each position along a regular grid is scanned individually, …

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Evaluation of the NMR-MOUSE as a new method for continuous functional monitoring of the small intestine during different perfusion states in a porcine model

Objective The study aim was to evaluate a small low-field NMR (nuclear magnetic resonance) scanner, the NMR-MOUSE®, for detecting changes in intestinal diffusion under different (patho-) physiological perfusion states. Methods Laparotomy was performed on 8 female landrace pigs (body weight 70±6 kg) and the feeding vessels of several intestinal loops were dissected. Successively, the intestinal …

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Measuring diffusion–relaxation correlation maps using non-uniform field gradients of single-sided NMR devices

Single-sided NMR systems are becoming a relevant tool in industry and laboratory environments due to their low cost, low maintenance and capacity to evaluate quantity and quality of hydrogen based materials. The performance of such devices has improved significantly over the last decade, providing increased field homogeneity, field strength and even controlled static field gradients. For …

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An estimation method of MR signal parameters for improved image reconstruction in unilateral scanner.

Unilateral NMR devices are a valuable tool in various applications such as non-destructive testing or well logging, but are not applied routinely for biomedical imaging. A low cost, unilateral and portable MRI can introduce MRI into clinical applications previously non-feasible, exploiting the advantages of the open architecture, the portability and affordable costs of these scanners. …

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Miniaturized multi-coil arrays for functional planar imaging with a single-sided NMR sensor

Nowadays most low-field NMR sensors, such as the single-sided Profile NMR-MOUSE®, still suffer from poor sensitivity, either resulting from low magnetic field strengths and correspondingly low NMR frequencies, or lack of sensitivity. Generally, micro-coils can improve sensitivity, but due to their small size, and thus small inductance, they are mainly used for high-field NMR. Their main application field is parallel …

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