scholarly journals Operational Amplifiers Revisited for Low Field Magnetic Resonance Relaxation Time Measurement Electronics

Proceedings ◽  
2019 ◽  
Vol 42 (1) ◽  
pp. 1
Author(s):  
Najlaa K. Almazrouei ◽  
Michael I. Newton ◽  
Robert H. Morris
Keyword(s):  
Relaxation Time ◽  
Magnetic Resonance ◽  
Field Measurements ◽  
Time Measurement ◽  
Operational Amplifiers ◽  
Frequency Range ◽  
Sensor Applications ◽  
Low Field ◽  
Front End ◽  
Resonance Relaxation

Advances in permanent magnet technology has seen more reports of sensor applications of low field magnetic resonance. Whilst most are either in the 10–20 MHz range or in the earth’s field, measurements at below 1 MHz are beginning to become more widespread. This range is below the need for careful radio frequency electronics design but above the audio domain and represents an interesting cross over. Many commercial spectrometers do not include the pulse power amplifier, duplexer and preamplifier as these depend on the frequency range used. In this work we demonstrate that, with the current specifications of the humble operational amplifier, the most simple form of an inverting design using only two resistors and decoupling, can effectively provide this ‘front end’ electronics. The low powers used mean crossed Ge diodes provide an excellent duplexer and it is suitable for battery powered applications.

scholarly journals Rapid Identification of Adulteration in Edible Vegetable Oils Based on Low-Field Nuclear Magnetic Resonance Relaxation Fingerprints

Foods ◽  
2021 ◽  
Vol 10 (12) ◽  
pp. 3068
Author(s):  
Zhi-Ming Huang ◽  
Jia-Xiang Xin ◽  
Shan-Shan Sun ◽  
Yi Li ◽  
Da-Xiu Wei ◽  
...  
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Vegetable Oils ◽  
Professional Training ◽  
Univariate Analysis ◽  
Rapid Identification ◽  
Resonance Spectroscopy ◽  
Low Field ◽  
Resonance Relaxation ◽  
Nuclear Magnetic

Most current approaches applied for the essential identification of adulteration in edible vegetable oils are of limited practical benefit because they require long analysis times, professional training, and costly instrumentation. The present work addresses this issue by developing a novel simple, accurate, and rapid identification approach based on the magnetic resonance relaxation fingerprints obtained from low-field nuclear magnetic resonance spectroscopy measurements of edible vegetable oils. The relaxation fingerprints obtained for six types of edible vegetable oil, including flaxseed oil, olive oil, soybean oil, corn oil, peanut oil, and sunflower oil, are demonstrated to have sufficiently unique characteristics to enable the identification of the individual types of oil in a sample. By using principal component analysis, three characteristic regions in the fingerprints were screened out to create a novel three-dimensional characteristic coordination system for oil discrimination and adulteration identification. Univariate analysis and partial least squares regression were used to successfully quantify the oil adulteration in adulterated binary oil samples, indicating the great potential of the present approach on both identification and quantification of edible oil adulteration.

Earliest cardiac toxicity induced by iron overload selectively inhibits electrical conduction

2002 ◽  
Vol 93 (2) ◽  
pp. 746-751 ◽  
Author(s):  
Kenneth A. Schwartz ◽  
Zy Li ◽  
Dianne E. Schwartz ◽  
Thomas G. Cooper ◽  
W. Emmett Braselton
Keyword(s):  
Relaxation Time ◽  
Magnetic Resonance ◽  
Left Ventricular Pressure ◽  
Left Ventricular ◽  
Warning Signs ◽  
Cardiac Conduction ◽  
Ventricular Contractility ◽  
Iron Load ◽  
High Incidence ◽  
Resonance Relaxation

Female guinea pigs were injected intraperitoneally with 0.083 g/kg iron dextran (Fe-D) to achieve progressively increasing levels of iron load; controls received dextran. Delayed and blocked cardiac conductivity at the Purkinje fiber-papillary muscle junction was initially observed with Fe-D loads of 0.33 g/kg. Serial magnetic resonance relaxation time measurements obtained from livers of live animals showed a decrease (8.1 ± 0.86 vs. 14.8 ± 1.03 ms in controls, P < 0.001) that was first observed in animals loaded with 0.25 g/kg Fe-D. Iron concentrations in hearts and livers were significantly increased ( P < 0.001). Left ventricular pressure measurements on 1.5 g/kg Fe-D animals failed to demonstrate a defect in contractility, but 27% (9/33) ( P < 0.050) of the animals died without warning signs. We conclude that 1) initial decreases in liver magnetic resonance-relaxation time occur in the same range of iron excess as the threshold of iron load that induces delay or blockade of cardiac conduction and 2) a high incidence of sudden death, presumably from cardiac arrhythmias, was observed with large doses of iron that did not decrease left ventricular contractility.

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