Glycogen plays essential roles in glucose metabolism.Imaging glycogen in the liver,the major glycogen reservoir in the body,may shed new light on many metabolic disorders.^(13)C magnetic resonance spectroscopy(MRS)has...Glycogen plays essential roles in glucose metabolism.Imaging glycogen in the liver,the major glycogen reservoir in the body,may shed new light on many metabolic disorders.^(13)C magnetic resonance spectroscopy(MRS)has become the mainstream method for monitoring glycogen in the body.However,the equipment of special hard-ware to standard clinical magnetic resonance imaging(MRI)scanners limits its clinical applications.Herein,we utilized endogenous glycogen as a T_(2)-based relaxation contrast agent for imaging glycogen metabolism in the liver in vivo.The in vitro results demonstrated that the transverse relaxation rate of glycogen strongly correlates with the concentration,pH,and field strength.Based on the Swift-Connick theory,we characterized the exchange property of glycogen and measured the exchange rate of glycogen as 31,847 Hz at 37°C.Besides,the viscosity and echo spacing showed no apparent effect on the transverse relaxation rate.This unique feature enables vi-sualization of glycogen signaling in vivo through T_(2)-weighted MRI.Two hours-post intraperitoneal injection of glucagon,a clinical drug to promote glycogenolysis and gluconeogenesis,the signal intensity of the mice’s liver increased by 1.8 times from the T_(2)-weighted imaging experiment due to the decomposition of glycogen.This study provides a convenient imaging strategy to non-invasively investigate glycogen metabolism in the liver,which may find clinical applications in metabolic diseases.展开更多
Nuclear magnetic resonance gyroscope (NMRG) has the characteristics of high precision and miniaturization, and is one of the main applications of quantum technology in the field of navigation. The transverse relaxatio...Nuclear magnetic resonance gyroscope (NMRG) has the characteristics of high precision and miniaturization, and is one of the main applications of quantum technology in the field of navigation. The transverse relaxation time (T_(2)) of the xenon nuclear spin in the atomic cell of the NMRG directly affects the angular random walk of the gyro. Accurate and rapid measurement of T_(2) is conducive to further improvement of gyroscope. At present, for the measurement of T_(2), the schemes of two orthogonal lasers for pumping and detecting are usually used. By applying two fast-switching orthogonal static magnetic fields and a single beam of circularly polarized laser with corresponding wavelength to pump the atomic cell, the xenon nuclear macroscopic magnetic moment Larmor precession is generated. The cesium atoms parametric magnetometer in cell is formed to detect the free induction decay signal generated by nuclear spin precession of xenon atoms. The measurement of T_(2) by a single laser simplifies the measurement equipment compared with traditional method with two lasers. The experimental results show that the T_(2) of xenon atoms is more than 10 s, and the effects of temperature are studied, which lay the foundation for the subsequent improvement of gyro performance.展开更多
A new method to predict the seed vigor of rice was developed to control adulteration during the seed trading process and to address the deficiencies of traditional manual detection methods.Low-field nuclear magnetic r...A new method to predict the seed vigor of rice was developed to control adulteration during the seed trading process and to address the deficiencies of traditional manual detection methods.Low-field nuclear magnetic resonance(LF-NMR)technique was used to detect the vigor of rice seeds.Four varieties(Beijing-1,Qianchonglang-2,Yanfeng-47 and Shennong-265)of rice seeds from the Rice Research Institute of Shenyang Agricultural University were chosen for the experiment.The transverse relaxation time T_(2),T_(21) and T_(22) were observed in the experiment.The peak start time of free water(transverse relaxation time T_(22)),signal amplitude of bound water(transverse relaxation time T_(21)),and moisture content decreased with the decrease in the vigor of the seeds.There were no obvious trends observed for the top of the peak and the end point of the transverse relaxation time T_(22).In addition,the start,top,and end time of the peak(transverse relaxation time T_(21)),and the signal amplitude of bound water showed no consistent changes.The results indicated that LF-NMR could be used as a method to distinguish the vigor of rice seeds rapidly.This study provided theoretical basis and technical support for the rapid detection of rice seed vigor.展开更多
The factors influencing dormancy release in lily bulbs strongly affect commercialization success, but the mechanism of dormancy release is still unclear. Magnetic resonance imaging (MRI) can detect changes in morpholo...The factors influencing dormancy release in lily bulbs strongly affect commercialization success, but the mechanism of dormancy release is still unclear. Magnetic resonance imaging (MRI) can detect changes in morphology and water status in a living plant bulb and aid in investigating release factors. To evaluate whether MRI could be used to detect intra-bulb metabolic changes during the dormant period in Oriental Lilies (Lilium 'Sorbonne'), a series of MRI and sugar concentration measurements were performed weekly on bulbs stored for 11 weeks at 4°C. The image quality of intra-bulb structure obtained using T 1-weighted imaging was superior to that obtained using T 2 -weighted imaging and had a higher signal-to-noise ratio (0.97±0.01). Magnetization transfer ratio values for the bud and basal plate declined during the first eight weeks of cold storage (P>0.05), and were well correlated with concentration of soluble sugar in the bud (R 2 =0.95) and basal plate (R 2 =0.93). Thus, MRI can serve as a valuable tool for observation and analysis of dynamic morphological and metabolic changes in vivo during dormancy release. This information is potentially useful as a guide in the improvement of horticultural product quality.展开更多
In order to accurately describe the transverse relaxation characteristic and stress relaxation modulus of HTPB coating during pre-strain thermal aging process,a one month thermal aging test was carried out at70C with ...In order to accurately describe the transverse relaxation characteristic and stress relaxation modulus of HTPB coating during pre-strain thermal aging process,a one month thermal aging test was carried out at70C with pre-strain of 0%,3%,6%and 9%,respectively.The low-field1 H NMR and stress relaxation modulus tests were carried out for HTPB coating at different aging stages.The stress relaxation model considering the molecular chains was proposed according to the changes of crosslinking chain and dangling chain of HTPB coating during pre-strain aging.The results showed that with the increase of aging time,the decay rate of transverse relaxation curve became faster,the transverse relaxation time decreased,the value of combined parameter q Mrl increased,the proportion of crosslinking chain decreased,while the proportion of dangling chain increased.Moreover,the stress relaxation modulus increased,the crosslinking network structure of HTPB coating became denser and the degree of crosslinking increased.At the initial aging stage,the pre-strain will destroy the crosslinking network structure of HTPB coating to a certain extent.With the increase of aging time,the effect of pre-strain will gradually weaken and the influence of aging on materials will gradually increase.The correlations between the stress relaxation model considering the molecular chains and the test results were more than 0.9950,which can accurately describe the stress relaxation modulus of HTPB coating during the pre-strain thermal aging process.展开更多
基金This work is supported by the National Key R&D Program of China(2018YFA0704000)the National Natural Science Foundation of China(91859206,U21A20392,82127802 and 21921004)+2 种基金the Key Research Program of Frontier Sciences,Chinese Academy of Sciences(ZDBS-LY-JSC004)the Scientific Instrument Developing Project of the Chi-nese Academy of Sciences(GJJSTD20200002)Xin Zhou acknowledges the support from the Tencent Foundation through the XPLORER PRIZE.
文摘Glycogen plays essential roles in glucose metabolism.Imaging glycogen in the liver,the major glycogen reservoir in the body,may shed new light on many metabolic disorders.^(13)C magnetic resonance spectroscopy(MRS)has become the mainstream method for monitoring glycogen in the body.However,the equipment of special hard-ware to standard clinical magnetic resonance imaging(MRI)scanners limits its clinical applications.Herein,we utilized endogenous glycogen as a T_(2)-based relaxation contrast agent for imaging glycogen metabolism in the liver in vivo.The in vitro results demonstrated that the transverse relaxation rate of glycogen strongly correlates with the concentration,pH,and field strength.Based on the Swift-Connick theory,we characterized the exchange property of glycogen and measured the exchange rate of glycogen as 31,847 Hz at 37°C.Besides,the viscosity and echo spacing showed no apparent effect on the transverse relaxation rate.This unique feature enables vi-sualization of glycogen signaling in vivo through T_(2)-weighted MRI.Two hours-post intraperitoneal injection of glucagon,a clinical drug to promote glycogenolysis and gluconeogenesis,the signal intensity of the mice’s liver increased by 1.8 times from the T_(2)-weighted imaging experiment due to the decomposition of glycogen.This study provides a convenient imaging strategy to non-invasively investigate glycogen metabolism in the liver,which may find clinical applications in metabolic diseases.
基金the Shanghai Aerospace Advanced Technology Joint Research Fund(No.USCAST2019-23)。
文摘Nuclear magnetic resonance gyroscope (NMRG) has the characteristics of high precision and miniaturization, and is one of the main applications of quantum technology in the field of navigation. The transverse relaxation time (T_(2)) of the xenon nuclear spin in the atomic cell of the NMRG directly affects the angular random walk of the gyro. Accurate and rapid measurement of T_(2) is conducive to further improvement of gyroscope. At present, for the measurement of T_(2), the schemes of two orthogonal lasers for pumping and detecting are usually used. By applying two fast-switching orthogonal static magnetic fields and a single beam of circularly polarized laser with corresponding wavelength to pump the atomic cell, the xenon nuclear macroscopic magnetic moment Larmor precession is generated. The cesium atoms parametric magnetometer in cell is formed to detect the free induction decay signal generated by nuclear spin precession of xenon atoms. The measurement of T_(2) by a single laser simplifies the measurement equipment compared with traditional method with two lasers. The experimental results show that the T_(2) of xenon atoms is more than 10 s, and the effects of temperature are studied, which lay the foundation for the subsequent improvement of gyro performance.
基金The project was supported by National Natural Science Foundation of China(Grant No.31701318 and 31601216)National Natural Science Foundation of China Projects of International Cooperation and Exchanges(Grant No.31811540396)+1 种基金National Key Research and Development Program of China(Grant No.2017YFD0701205)Doctoral Research Fund of Liaoning Province,China(Grant No.20170520202).
文摘A new method to predict the seed vigor of rice was developed to control adulteration during the seed trading process and to address the deficiencies of traditional manual detection methods.Low-field nuclear magnetic resonance(LF-NMR)technique was used to detect the vigor of rice seeds.Four varieties(Beijing-1,Qianchonglang-2,Yanfeng-47 and Shennong-265)of rice seeds from the Rice Research Institute of Shenyang Agricultural University were chosen for the experiment.The transverse relaxation time T_(2),T_(21) and T_(22) were observed in the experiment.The peak start time of free water(transverse relaxation time T_(22)),signal amplitude of bound water(transverse relaxation time T_(21)),and moisture content decreased with the decrease in the vigor of the seeds.There were no obvious trends observed for the top of the peak and the end point of the transverse relaxation time T_(22).In addition,the start,top,and end time of the peak(transverse relaxation time T_(21)),and the signal amplitude of bound water showed no consistent changes.The results indicated that LF-NMR could be used as a method to distinguish the vigor of rice seeds rapidly.This study provided theoretical basis and technical support for the rapid detection of rice seed vigor.
基金supported by the Special Fund for Agro-scientific Research in the Public Interest (Grant No. 200903020)
文摘The factors influencing dormancy release in lily bulbs strongly affect commercialization success, but the mechanism of dormancy release is still unclear. Magnetic resonance imaging (MRI) can detect changes in morphology and water status in a living plant bulb and aid in investigating release factors. To evaluate whether MRI could be used to detect intra-bulb metabolic changes during the dormant period in Oriental Lilies (Lilium 'Sorbonne'), a series of MRI and sugar concentration measurements were performed weekly on bulbs stored for 11 weeks at 4°C. The image quality of intra-bulb structure obtained using T 1-weighted imaging was superior to that obtained using T 2 -weighted imaging and had a higher signal-to-noise ratio (0.97±0.01). Magnetization transfer ratio values for the bud and basal plate declined during the first eight weeks of cold storage (P>0.05), and were well correlated with concentration of soluble sugar in the bud (R 2 =0.95) and basal plate (R 2 =0.93). Thus, MRI can serve as a valuable tool for observation and analysis of dynamic morphological and metabolic changes in vivo during dormancy release. This information is potentially useful as a guide in the improvement of horticultural product quality.
基金supported by the National Defense Pre-Research Projects[grant number ZS2015070132A12002]。
文摘In order to accurately describe the transverse relaxation characteristic and stress relaxation modulus of HTPB coating during pre-strain thermal aging process,a one month thermal aging test was carried out at70C with pre-strain of 0%,3%,6%and 9%,respectively.The low-field1 H NMR and stress relaxation modulus tests were carried out for HTPB coating at different aging stages.The stress relaxation model considering the molecular chains was proposed according to the changes of crosslinking chain and dangling chain of HTPB coating during pre-strain aging.The results showed that with the increase of aging time,the decay rate of transverse relaxation curve became faster,the transverse relaxation time decreased,the value of combined parameter q Mrl increased,the proportion of crosslinking chain decreased,while the proportion of dangling chain increased.Moreover,the stress relaxation modulus increased,the crosslinking network structure of HTPB coating became denser and the degree of crosslinking increased.At the initial aging stage,the pre-strain will destroy the crosslinking network structure of HTPB coating to a certain extent.With the increase of aging time,the effect of pre-strain will gradually weaken and the influence of aging on materials will gradually increase.The correlations between the stress relaxation model considering the molecular chains and the test results were more than 0.9950,which can accurately describe the stress relaxation modulus of HTPB coating during the pre-strain thermal aging process.
