Since high magnetic field(MF) intensity can improve the image quality and reduce magnetic resonance imaging(MRI) acquisition time, the field intensity of MRIs has continued to increase over the past few decades. A...Since high magnetic field(MF) intensity can improve the image quality and reduce magnetic resonance imaging(MRI) acquisition time, the field intensity of MRIs has continued to increase over the past few decades. Although MRIs in most current hospitals are 0.5 T–3 T, there are preclinical studies have been carried out using 9.4 T MRI, and engineers are also putting efforts on building MRIs with even higher MFs. However, the accompanied safety issue of high-field MRIs is an emergent question to address before their clinical applications. In the meantime, the static magnetic field(SMF) has been shown to inhibit tumor growth in previous studies. Here, we investigated both the safety issue and the anti-tumor potentials of 3.7 T–24.5 T SMFs on GIST-T1 gastrointestinal stromal tumor-bearing nude mice. We followed up the mice three weeks after their exposure to high SMF and found that none of the mice died or had severe organ damage, except for slightly decreased food intake, weight gain, and liver function. Moreover, the tumor growth was inhibited by 3.7 T–24.5 T SMFs(up to ~54%). It is interesting that the effects are more dependent on MF gradient than intensities, and for the same gradient and intensity, mice responded differently to hypogravity and hypergravity conditions. Therefore, our study not only demonstrated the safeness of high SMFs up to 24.5 T on mice but also revealed their anti-tumor potentials in the future.展开更多
We report the first atomically resolved scanning tunneling microscope (STM) imaging in a water-cooled magnet (WM), for which extremely harsh vibrations and noise have been the major challenge. This custom WM-STM f...We report the first atomically resolved scanning tunneling microscope (STM) imaging in a water-cooled magnet (WM), for which extremely harsh vibrations and noise have been the major challenge. This custom WM-STM features an ultra-rigid and compact scan head in which the coarse approach is driven by our newly designed TunaDrive piezoelectric motor. A three-level spring hanging system is used for vibration isolation. Room-temperature raw-data images of graphite with quality atomic resolution were acquired in the presence of very strong magnetic fields, with a field strength up to 27 T, in a 32-mm-diameter bore WM with a maximum field strength of 27.5 T at a power rating of 10 MW, calibrated by nuclear magnetic resonance (NMR). This record field strength of 27 T exceeds the maximal field strength achieved by the conventional supercon- ducting magnets. Besides, our WM-STM has paved the way to STM imaging using a 45 T, 32-mm-diameter bore hybrid magnet, which is the world's flagship magnet, producing the strongest steady magnetic field.展开更多
基金Project supported by the National Key R&D Program of China(Grant Nos.2016YFA0400900 and 2017YFA0402903)the National Natural Science Foundation of China(Grant Nos.U1532151 and 51627901)+2 种基金the Major/Innovative Program of Development Foundation of Hefei Center for Physical Science,Technology(Grant No.2016FXCX004)Hefei Science Center,CAS(Grant No.2016HSC-IU007)the CASHIPS Director’s Fund(Grant No.YZJJ201704)to Qingyou Lu and Xin Zhang
文摘Since high magnetic field(MF) intensity can improve the image quality and reduce magnetic resonance imaging(MRI) acquisition time, the field intensity of MRIs has continued to increase over the past few decades. Although MRIs in most current hospitals are 0.5 T–3 T, there are preclinical studies have been carried out using 9.4 T MRI, and engineers are also putting efforts on building MRIs with even higher MFs. However, the accompanied safety issue of high-field MRIs is an emergent question to address before their clinical applications. In the meantime, the static magnetic field(SMF) has been shown to inhibit tumor growth in previous studies. Here, we investigated both the safety issue and the anti-tumor potentials of 3.7 T–24.5 T SMFs on GIST-T1 gastrointestinal stromal tumor-bearing nude mice. We followed up the mice three weeks after their exposure to high SMF and found that none of the mice died or had severe organ damage, except for slightly decreased food intake, weight gain, and liver function. Moreover, the tumor growth was inhibited by 3.7 T–24.5 T SMFs(up to ~54%). It is interesting that the effects are more dependent on MF gradient than intensities, and for the same gradient and intensity, mice responded differently to hypogravity and hypergravity conditions. Therefore, our study not only demonstrated the safeness of high SMFs up to 24.5 T on mice but also revealed their anti-tumor potentials in the future.
文摘We report the first atomically resolved scanning tunneling microscope (STM) imaging in a water-cooled magnet (WM), for which extremely harsh vibrations and noise have been the major challenge. This custom WM-STM features an ultra-rigid and compact scan head in which the coarse approach is driven by our newly designed TunaDrive piezoelectric motor. A three-level spring hanging system is used for vibration isolation. Room-temperature raw-data images of graphite with quality atomic resolution were acquired in the presence of very strong magnetic fields, with a field strength up to 27 T, in a 32-mm-diameter bore WM with a maximum field strength of 27.5 T at a power rating of 10 MW, calibrated by nuclear magnetic resonance (NMR). This record field strength of 27 T exceeds the maximal field strength achieved by the conventional supercon- ducting magnets. Besides, our WM-STM has paved the way to STM imaging using a 45 T, 32-mm-diameter bore hybrid magnet, which is the world's flagship magnet, producing the strongest steady magnetic field.
基金This work was supported by the Chinese Academy of Sciences 'Hundred Talent program' and National Natural Science Foundation of China (No.U1532151)to X.Z.and by Chinese national high magnetic field facilities,the Fundamental Research Funds for the Central Universities (No.WK2340000035) and National Natural Science Foundation of China (Nos.U1232210,11204306,and 11374278) to Q.Y.L.