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Mobile single-sided NMR

Progress in Nuclear Magnetic Resonance Spectroscopy (Impact Factor: 8.71). 05/2008; 52(4):197-269. DOI: 10.1016/j.pnmrs.2007.10.002
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    • "There are several factors responsible for that. Most importantly, the inhomogeneous B 0 and B 1 fields lead to a distribution of RF pulses across the sensitive volume [15] [29], producing multiple magnetization pathways and reducing the contribution of the ideal (90–180–180–. . .) pathway to the total NMR signal with every subsequent echo. "
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    ABSTRACT: An NMR signal from a sample in a constant stray field of a portable NMR sensor is sensitized to vibrations. The CPMG sequence is synchronized to vibrations so that the constant gradient becomes an “effective” square-wave gradient, leading to the vibration-induced phase accumulation. The integrating nature of the spot measurement, combined with the phase distribution due to a non-uniform gradient and/or a wave field, leads to a destructive interference, the drop in the signal intensity and changes in the echo train shape. Vibrations with amplitudes as small as 140 nm were reliably detected with the permanent gradient of 12.4 T/m. The signal intensity depends on the phase offset between the vibrations and the pulse sequence. This approach opens the way for performing elastometry and micro-rheology measurements with portable NMR devices beyond the walls of a laboratory. Even without synchronization, if a vibration frequency is comparable to 1/2TE of the CPMG sequence, the signal can be severely affected, making it important for potential industrial applications of stray-field NMR.
    Journal of Magnetic Resonance 10/2014; 248:1-7. DOI:10.1016/j.jmr.2014.09.003 · 2.32 Impact Factor
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    • "As a versatile analytical technique, nuclear magnetic resonance (NMR) has been used not only in fundamental research in physics, chemistry and biology, but also for practical applications such as medical imaging and oil well logging [1]. However, the poor sensitivity of conventional inductive pick-up coils at low frequency hinders many possible applications, and hence most endeavors in enhancing sensitivity focus on high-field NMR. "
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    ABSTRACT: We present a Cs atomic magnetometer with a sensitivity of 150fT/Hz(1/2) operating near room temperature. The nuclear magnetic resonance (NMR) signal of 125μL tap water was detected at an ultralow magnetic field down to 47nT, with the signal-to-noise ratio (SNR) of the NMR signal approaching 50 after eight averages. Relaxivity experiments with a Gd(DTPA) contrast agent in zero field were performed, in order to show the magnetometer's ability to measure spin-lattice relaxation time with high accuracy. This demonstrates the feasibility of an ultralow field NMR spectrometer based on a Cs atomic magnetometer, which has a low working temperature, short data acquisition time and high sensitivity. This kind of NMR spectrometer has great potential in applications such as chemical analysis and magnetic relaxometry detection in ultralow or zero fields.
    Journal of Magnetic Resonance 10/2013; 237C:158-163. DOI:10.1016/j.jmr.2013.10.008 · 2.32 Impact Factor
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    • "However, this did not influence the detection efficiency of LF-NMR on QVOs adulterated with UFO from the adulteration detection point of view. T 2 distribution mainly depends on the homogeneity of the magnetic field where the hydrogen proton locates, and the homogeneity of the magnet field is mainly determined by the main magnetic field (magnet) and the local magnetic field (precessional motion of hydrogen proton) of the internal composition of the measured material (Blümich et al. 2008; Fukui 2008). Therefore, when the main magnetic field's intensity is stabilized, the factor influencing T 2 distribution is the research object's constituents or the interior chemical structure of the components in detail. "
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    ABSTRACT: Pleasant flavor and nutritional benefits of vegetable oils lead to an increase in their consumption amount. In addition, due to being apparently similar to commercially qualified vegetable oils (QVOs), used frying oil (UFO) is added into it to seek high profit by the unscrupulous traders. Thus, the authenticity assurance of commercial oil and fat products remains a challenge to scientists both in terms of its health and commercial perspectives. This work focused on using low field nuclear magnetic resonance (LF-NMR) to discriminate the adulteration of commercial corn, peanut, rapeseed, and soybean oils with two kinds of UFOs. The differences between the transverse relaxation distributions (T 2 distributions) of qualified oil and UFO were in the appearance of the third peak (A), which could be assigned to polymer products that were produced during the deep-fat frying process and the shift of T 2 value of the peaks. In addition, the A peak area accounted for the whole area of peaks linearly increasing along with the increase in adulteration proportion. Based on the changes of peak area, a simple linear equation was built and the determination coefficients (R 2) were all higher than 0.93. Therefore, as a rapid, convenient, and nondestructive method, LF-NMR application could be used to detect adulteration of vegetable oils with UFO.
    Food and Bioprocess Technology 09/2013; 6(9):2562-2570. DOI:10.1007/s11947-012-0826-5 · 3.13 Impact Factor
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