Single-Sided Magnet System for Quantitative MR Relaxometry and Preclinical In-Vivo Monitoring.

Objective: We have developed a single-sided magnet system that allows Magnetic Resonance relaxation and diffusion parameters to be measured.

Methods: A single-sided magnet system has been developed, using an array of permanent magnets. The magnet positions are optimised to produce a B magnetic field with a spot that is relatively homogenous and can project into a sample.

Study of zeolite anti-caking effects for fertilisers by H low-field NMR.

Caking is associated with the consolidation of dry powder and granules, leading to losses of function and/or quality. It has been object of studies in the pharmaceutical, food and fertiliser areas since 1920's because of its significant impact on product quality and value. Caking has been described as a three-step event consisting of sorption-dissolution-recrystallisation phases and constitutes a critical factor in fertilisers losses during storage while also hampering fertiliser application.

Oxygen saturation-dependent effects on blood transverse relaxation at low fields.

Objective: Blood oxygenation can be measured using magnetic resonance using the paramagnetic effect of deoxy-haemoglobin, which decreases the [Formula: see text] relaxation time of blood. This [Formula: see text] contrast has been well characterised at the [Formula: see text] fields used in MRI (1.5 T and above).

MAS-NMR of [Pyr][TfN] and [Pyr][TfN] Ionic Liquids Confined to Carbon Black: Insights and Pitfalls.

Electrolytes based on ionic liquids (IL) are promising candidates to replace traditional liquid electrolytes in electrochemical systems, particularly in combination with carbon-based porous electrodes. Insight into the dynamics of such systems is imperative for tailoring electrochemical performance. In this work, 1-Methyl-1-propylpyrrolidinium bis(trifluoromethylsulfonyl)imide and 1-Hexyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide were studied in a carbon black (CB) host using spectrally resolved Carr-Purcell-Meiboom-Gill (CPMG) and 13-interval Pulsed Field Gradient Stimulated Echo (PFGSTE) Magic Angle Spinning Nuclear Magnetic Resonance (MAS-NMR).

Surface model of the human red blood cell simulating changes in membrane curvature under strain.

We present mathematical simulations of shapes of red blood cells (RBCs) and their cytoskeleton when they are subjected to linear strain. The cell surface is described by a previously reported quartic equation in three dimensional (3D) Cartesian space. Using recently available functions in Mathematica to triangularize the surfaces we computed four types of curvature of the membrane.

Quantitative measurement of solid fraction in a silo using SPRITE.

The purpose of this study is to develop MRI methods to measure the solid fraction in granular flows quantitatively. It is increasingly recognised that solid fraction plays a key role in granular rheology, but experimental characterisation of it during flow is challenging. Here centric sectoral-SPRITE imaging is applied to image mustard seeds discharging from a 3D-printed hopper.

Enhanced Ca influx in mechanically distorted erythrocytes measured with F nuclear magnetic resonance spectroscopy.

We present the first direct nuclear magnetic resonance (NMR) evidence of enhanced entry of Ca ions into human erythrocytes (red blood cells; RBCs), when these cells are mechanically distorted. For this we loaded the RBCs with the fluorinated Ca chelator, 1,2-bis(2-amino-5-fluorophenoxy)ethane-N,N,N',N'-tetraacetic acid (5FBAPTA), and recorded F NMR spectra. The RBCs were suspended in gelatin gel in a special stretching/compression apparatus.

On the influence of rotational motion on MRI velocimetry of granular flows - Theoretical predictions and comparison to experimental data.

Continuum dynamics of granular materials are known to be influenced by rotational, as well as translational, motion. Few experimental techniques exist that are sensitive to rotational motion. Here we demonstrate that MRI is sensitive to the rotation of granules and that we can quantify its effect on the MRI signal.

Threshold Isocontouring on High b-Value Diffusion-Weighted Images in Magnetic Resonance Mammography.

Objectives: Motivated by the similar appearance of malignant breast lesions in high b-value diffusion-weighted imaging (DWI) and positron emission tomography, the purpose of this work was to evaluate the applicability of a threshold isocontouring approach commonly used in positron emission tomography to analyze DWI data acquired from female human breasts with minimal interobserver variability.

Methods: Twenty-three female participants (59.4 ± 10.

Rheo-NMR in food science-Recent opportunities.

For over 25 years, nuclear magnetic resonance (NMR) and magnetic resonance imaging (MRI) techniques have been used to study materials under mechanical deformation. Collectively, these methods are referred to as Rheo-NMR. In many cases, it provides spatially and temporally resolved maps of NMR spectra, intrinsic NMR parameters (such as relaxation times), or motion (such as diffusion or flow).

Evaluation of benchtop NMR Diffusion Ordered Spectroscopy for small molecule mixture analysis.

Diffusion Ordered Spectroscopy (DOSY) is an attractive method for analyzing chemical mixtures in the liquid state because it separates spectra by the molecular weight of the associated molecule. It has been compared with hyphenated chromatographic and analytical methods such LC-MS and has broad potential in servicing those same applications including forensics, reaction analysis, quality control, and fraud detection. Benchtop NMR can collect quality spectra on small molecules, however, lacks the chemical shift dispersion of high field instruments, can suffer from spectral overlap common in mixtures, and the diminished sensitivity of the lower field compounds these problems.

Multilamellar Vesicle Formation Probed by Rheo-NMR and Rheo-SALS under Large Amplitude Oscillatory Shear.

The formation of multilamellar vesicles (MLVs) in the lyotropic lamellar phase of the system triethylene glycol mono n-decyl ether (CE)/water is investigated under large amplitude oscillatory shear (LAOS) using spatially resolved rheo-NMR spectroscopy and a combination of rheo-small angle light scattering (rheo-SALS) and conventional rheology. Recent advances in rheo-NMR hardware development facilitated the application of LAOS deformations in high-field NMR magnets. For the range of investigated strain amplitudes (10-50) and frequencies (1 and 2 rad s), MLV formation is observed in all NMR and most SALS experiments.

Quantifying NMR relaxation correlation and exchange in articular cartilage with time domain analysis.

Measured nuclear magnetic resonance (NMR) transverse relaxation data in articular cartilage has been shown to be multi-exponential and correlated to the health of the tissue. The observed relaxation rates are dependent on experimental parameters such as solvent, data acquisition methods, data analysis methods, and alignment to the magnetic field. In this study, we show that diffusive exchange occurs in porcine articular cartilage and impacts the observed relaxation rates in T-T correlation experiments.

Bone volume-to-total volume ratio measured in trabecular bone by single-sided NMR devices.

Purpose: Reduced bone strength is associated with a loss of bone mass, usually evaluated by dual-energy X-ray absorptiometry, although it is known that the bone microstructure also affects the bone strength. Here, a method is proposed to measure (in laboratory) the bone volume-to-total volume ratio by single-sided NMR scanners, which is related to the microstructure of the trabecular bone.

Methods: Three single-sided scanners were used on animal bone samples.

Determining mean fractional anisotropy using DDCOSY: preliminary results in biological tissues.

Complex materials are ubiquitous in science, engineering and nature. One important parameter for characterising their morphology is the degree of anisotropy. Magnetic resonance imaging offers non-invasive methods for quantitative measurements of the materials anisotropy, most commonly via diffusion tensor imaging and the subsequent extraction of the spatially resolved fractional anisotropy (FA) value.

Effect of magnetic pore surface coating on the NMR relaxation and diffusion signal in quartz sand.

Magnetic impurities are ubiquitous in natural porous media such as sand and soil. They generate internal magnetic field gradients because of increased magnetic susceptibility differences between solid and liquid phase in the pore space and because of the presence of magnetic centers. These internal gradients accelerate NMR relaxation rates and thus might limit the possibility of pore space characterization using NMR.

Obtaining T1-T2 distribution functions from 1-dimensional T1 and T2 measurements: The pseudo 2-D relaxation model.

We present the pseudo 2-D relaxation model (P2DRM), a method to estimate multidimensional probability distributions of material parameters from independent 1-D measurements. We illustrate its use on 1-D T1 and T2 relaxation measurements of saturated rock and evaluate it on both simulated and experimental T1-T2 correlation measurement data sets. Results were in excellent agreement with the actual, known 2-D distribution in the case of the simulated data set.

Fast reconstruction of highly undersampled MR images using one and two dimensional principal component analysis.

Recent compressed sensing techniques allow signal acquisition with less sampling than required by the Nyquist-Shannon theorem which reduces the data acquisition time in magnetic resonance imaging (MRI). However, prior knowledge becomes essential to reconstruct detailed features when the sampling rate is exceedingly low. In this work, one compressed sensing scheme developed in wireless sensing networks was adapted for the purpose of reconstructing magnetic resonance images by using one-dimensional principal component analysis (1D-PCA).

Real-time fluid transport characterization through direct acquisition of the averaged propagator.

Brownian motion (diffusion) and coherent flow are fundamental for many natural and artificial processes. Therefore, its accurate measurement and description is highly desirable in many areas of science, engineering, and technology. Currently available methods commonly involve multiple experiments and substantial processing of acquired data.

Advances and artefact suppression in RARE-velocimetry for flow with curved streamlines.

Method and considerations are presented that allow for an improved quantitative velocity measurement of complex fluids under shear using a fast 2D PGSE-RARE technique. While this contribution is relevant for shear geometries with rotational symmetry in general, the focus here is set on cylindrical Couette cells, a device most commonly used for rheological NMR investigations. The curved nature of the flow within the shearing geometry creates challenges in accurately determining the flow profile, as conventional imaging gradients naturally operate on a Cartesian grid.

Magnetic-resonance pore imaging of nonsymmetric microscopic pore shapes.

Imaging of the microstructure of porous media such as biological tissue or porous solids is of high interest in health science and technology, engineering and material science. Magnetic resonance pore imaging (MRPI) is a recent technique based on nuclear magnetic resonance (NMR) which allows us to acquire images of the average pore shape in a given sample. Here we provide details on the experimental design, challenges, and requirements of MRPI, including its calibration procedures.

Symmetry of the gradient profile as second experimental dimension in the short-time expansion of the apparent diffusion coefficient as measured with NMR diffusometry.

The time-dependent apparent diffusion coefficient as measured by pulsed gradient NMR can be used to estimate parameters of porous structures including the surface-to-volume ratio and the mean curvature of pores. In this work, the short-time diffusion limit and in particular the influence of the temporal profile of diffusion gradients on the expansion as proposed by Mitra et al. (1993) is investigated.