Single-Sided NMR

doi:10.1007/978-3-642-16307-4

Cited by 139 publications

(11 citation statements)

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“…In recent decades, there has been a concerted effort to develop more accessible, portable MR sensors [18,19]. Although fundamentally based on the same phenomena, conventional MRI and portable MR methods differ in many ways including the instrumentation employed, the information provided, and the applications targeted.…”

Section: Open Access Edited Bymentioning

confidence: 99%

Using phase interference to characterize dynamic properties—a review of constant gradient, portable magnetic resonance methods

et al. 2023

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Spatially resolved motion-sensitized magnetic resonance (MR) is a powerful tool for studying the dynamic properties of materials. Traditional methods involve using large, expensive equipment to create images of sample displacement by measuring the spatially resolved MR signal response to time-varying magnetic field gradients. In these systems, both the sample and the stress applicator are typically positioned inside a magnet bore. Portable MR instruments with constant gradients are more accessible, with fewer limitations on sample size, and they can be used in industrial settings to study samples under deformation or flow. We propose a view in which the well-controlled sensitive region of a magnet array acts as an integrator, with the velocity distribution leading to phase interference in the detected signal, which encodes information on the sample’s dynamic properties. For example, in laminar flows of Newtonian and non-Newtonian fluids, the velocity distribution can be determined analytically and used to extract the fluid’s dynamic properties from the MR signal magnitude and/or phase. This review covers general procedures, practical considerations, and examples of applications in dynamic mechanical analysis and fluid rheology (viscoelastic deformation, laminar pipe flows, and Couette flows). Given that these techniques are relatively uncommon in the broader magnetic resonance community, this review is intended for both advanced NMR users and a more general physics/engineering audience interested in rheological applications of NMR.

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Section: Open Access Edited Bymentioning

confidence: 99%

Using phase interference to characterize dynamic properties—a review of constant gradient, portable magnetic resonance methods

et al. 2023

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“…22 The calculation is based on obtaining a numerical solution to the Bloch equations for arbitrary values of B 0 and B 1 and for an arbitrary pulse excitation shape. Using the approximation of short (with respect to the transverse relaxation time) rectangular excitation pulses, a very efficient solution to the Bloch equations, eg, resulting from the method reported by Casanova and Perlo, 24 can be obtained. Here, we set the frequency of the excitation pulses to be equal to the average value of γB 0 in the ROI (γ is the electro-geomagnetic ratio).…”

Section: Predicted Esr-sensitive Volumementioning

confidence: 99%

Compact electron spin resonance skin oximeter: Properties and initial clinical results

Cristea

Wolfson

Ahmad

et al. 2020

Magnetic Resonance in Med

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Purpose Skin oxygen level is of significance for the diagnosis and treatment of many clinical problems, such as chronic wounds and diabetic foot ulcers. Furthermore, skin oxygen levels can be correlated to arterial oxygen partial pressure, thereby revealing potentially dangerous conditions such as hyperoxia (too much oxygen), which may occur in ventilated neonates. Traditionally, skin oxygen levels are measured using electrochemical methods and, more recently, also by fluorescence lifetime techniques. These approaches suffer from several drawbacks, rendering them suboptimal. The purpose of this work is to develop an electron spin resonance (ESR) ‐based method for monitoring oxygen partial pressure (pO2) in skin tissue. Methods A compact sensor for pulsed ESR is designed and constructed. Our ESR‐based method makes use of a unique exogenous paramagnetic spin probe that is placed on the skin in a special partially sealed sticker, and subsequently measuring its signal with the compact pulsed ESR sensor that includes a miniature magnet and a small S‐band (~2.3 GHz) microwave resonator. The inverse of the spin‐spin relaxation time (1/T2) measured by ESR is shown to be linearly correlated with pO2 levels. Results The sensor and its matching sticker were tested both in vitro and in vivo (with human subjects). Measured skin pO2 levels reached equilibrium after ~2‐3 h and were found to be comparable to those measured by continuous‐wave (CW) ESR using a large electromagnet. Conclusions A compact pulsed ESR sensor with a matching paramagnetic sticker can be used for pO2 monitoring of the skin tissue, similar to large bulky CW ESR systems.

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“…referred to as the 2.28 MHz magnet hereafter, is a 18 × 11 × 7 cm, 0.05 T unilateral permanent magnet with a homogeneous sweet spot 2.5 cm off the magnet surface (Garcia-Naranjo, Guo, Marica, Liao, & Balcom, 2014;Marble, Mastikhin, Colpitts, & Balcom, 2007). A ω o /2π = 2.28 MHz homebuilt surface coil designed for the 0.05 T magnet allows the sweet spots of the rf and static magnetic fields to coincide 2.5 cm above the magnet surface (Casanova, Perlo, & Blumich, 2011). The final sensor, which will be referred to as the 19.5 MHz magnet hereafter, is a 10 × 11 × 5 cm, 0.46 T permanent magnet equipped with a flat rf surface coil that is tuned and matched to ω o /2π = 19.5 MHz and a sweet spot standoff of 4 mm.…”

Section: Food Engineering Materials Science and Nanotechnologymentioning

confidence: 99%

Noninvasive, Nondestructive Measurement of Tomato Concentrate Spoilage in Large‐Volume Aseptic Packages

Martin

Balcom

McCarthy

et al. 2019

Journal of Food Science

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Low frequency nuclear magnetic resonance (NMR) is used to noninvasively and nondestructively detect spoiled tomato concentrate stored in >200 L metal‐lined containers. It is shown that longitudinal and transverse NMR relaxation times change as the tomato concentrate spoils. A rapid, viscosity‐dependent spoilage detection method that takes advantage of the inherent inhomogeneity in single‐sided NMR instruments is proposed. Here, the effective transverse magnetization decay rate is used as a parameter to determine tomato concentrate spoilage. Three different low frequency, single‐sided NMR instruments are described and compared to determine the optimum sensor for spoiled tomato concentrate detection in large‐format, metal‐lined, aseptic containers. The most effective NMR sensor for this application is temperature stable and has large magnetic field gradients and a homogeneous magnetic field region offset >0.5 cm from the magnet surface. Practical Application This manuscript describes a noninvasive and nondestructive tomato concentrate spoilage detector for application to large‐format, sealed, commercial storage bins.

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Single-Sided NMR

Cited by 139 publications

References 0 publications

Using phase interference to characterize dynamic properties—a review of constant gradient, portable magnetic resonance methods

Using phase interference to characterize dynamic properties—a review of constant gradient, portable magnetic resonance methods

Compact electron spin resonance skin oximeter: Properties and initial clinical results

Noninvasive, Nondestructive Measurement of Tomato Concentrate Spoilage in Large‐Volume Aseptic Packages

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