关键词: FID 信号, T2 弛豫时间, 水分结合状态, 质子密度, T1 加权成像

Abstract:

Low field (0.01 to 0.5 Tesla) nuclear magnetic resonance (NMR) instrument has spread out its applications in many fields such as food manufacture, petroleum industry,agriculture, matireal research and so on because of its low cost and easy maintenance. For the purpose of explaining the dynamic water absorbing process of mung beans from a new point of view, lowfield NMR technology was adopted in this study. Mung beans were immersed in watre and taken out every 0.5 hfor the testing of FID signal and T2 relaxation time and every 1 h for the NMR imaging. The water absorption of mung beans has a quick rise after 3 hours and enters into a stable period after 5.5 hours. There are three states of water in the mung beans including capillary water T21, free water T22 and bound water T23. Capillary water T21 exhibited a wave-like movements change and free water T22 and bound water T23 had a similar change: stable-rising-stable. Free water as a good solvent participates in different types of biochemical reaction and therefore the increase of proton density value (signal value) of free water was the biggest. The NRM images showed that the watrer absorbing of mung bean was started hilum. Our study results prove that low-field NMR technology also can be applied in the studies of seed immersion of other grains.

Key words: FID signal, T2 relaxation, Combination State of Water, Proton Density, T1 Weighted Imaging