Chemistry: Breaking the billion-hertz barrier

Bhattacharya, Ananyo

doi:10.1038/463605a

Cited by 44 publications

(31 citation statements)

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“…Usually, the current densities for MRI applications below 9.4 T are in the range of several 100 A/mm 2 . At present, MRI scanners using magnets with bore sizes of C68 cm are not commercially available above 11.7 T. However, there are analytical NMR systems operating at up to 23.5 T (Bhattacharya 2010) and dedicated small bore (animal) MRI systems on the market operating at field strength up to 17.2 T. The critical current density of NbTi decreases above 10 T considerably (see Fig. 9) when operating it at 4.2 K. By a reduction of the temperature to 2 K, NbTi can be used up to 11.7 T, but this is the limit for this conductor.…”

Section: Superconductormentioning

confidence: 98%

High-Field Superconducting Magnets

Liebel

2011

Medical Radiology

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Section: Superconductormentioning

confidence: 98%

High-Field Superconducting Magnets

Liebel

2011

Medical Radiology

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“…At 1 GHz new horizons open in structural biology, metabolomics and material science. Although the increase in field strength is only about 11% over previously available 900 MHz spectrometers, there is a significant increase in speed and sensitivity for low concentration samples [36].…”

Section: Analytical Nmrmentioning

confidence: 99%

Ultra-High Field NMR and MRI—The Role of Magnet Technology to Increase Sensitivity and Specificity

Moser

Laistler

Schmitt³

et al. 2017

Front. Phys.

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"History, of course, is difficult to write, if for no other reason, than that it has so many players and so many authors." -P. J. Keating (former Australian Prime Minister)Starting with post-war developments in nuclear magnetic resonance (NMR) a race for stronger and stronger magnetic fields has begun in the 1950s to overcome the inherently low sensitivity of this promising method. Further challenges were larger magnet bores to accommodate small animals and eventually humans. Initially, resistive electromagnets with small pole distances, or sample volumes, and field strengths up to 2.35 T (or 100 MHz 1 H frequency) were used in applications in physics, chemistry, and material science. This was followed by stronger and more stable (Nb-Ti based) superconducting magnet technology typically implemented first for small-bore systems in analytical chemistry, biochemistry and structural biology, and eventually allowing larger horizontal-bore magnets with diameters large enough to fit small laboratory animals. By the end of the 1970s, first low-field resistive magnets big enough to accommodate humans were developed and superconducting whole-body systems followed. Currently, cutting-edge analytical NMR systems are available at proton frequencies up to 1 GHz (23.5 T) based on Nb 3 Sn at 1.9 K. A new 1.2 GHz system (28 T) at 1.9 K, operating in persistent mode but using a combination of low and high temperature multi-filament superconductors is to be released. Preclinical instruments range from small-bore animal systems with typically 600-800 MHz (14.1-18.8 T) up to 900 MHz (21 T) at 1.9 K. Human whole-body MRI systems currently operate up to 10.5 T. Hybrid combined superconducting and resistive electromagnets with even higher field strength of 45 T dc and 100 T pulsed, are available for material research, of course with smaller free bore diameters. This rather costly development toward higher and higher field strength is a consequence of the inherently low and, thus, urgently needed sensitivity in all NMR experiments. This review particularly describes and compares the developments in superconducting magnet technology and, thus, sensitivity in three Moser et al.UHF MR-Magnet Technology fields of research: analytical NMR, biomedical and preclinical research, and human MRI and MRS, highlighting important steps and innovations. In addition, we summarize our knowledge on safety issues. An outlook into even stronger magnetic fields using different superconducting materials and/or hybrid magnet designs is presented.

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“…Very high magnetic fields are now available and facilitate the study of quadrupolar nuclei (nuclear spin quantum number, I > 1 2 ) in inorganic materials, 3,11 or more recently, the first 23.5 T commercial instrument in Lyon, France. 12 Further, the suppression of significant homogeneous and inhomogeneous broadening interactions has been achieved by spinning samples up to 70 kHz (in 1.3 mm commercial sample carriers (rotors)) compared to a maximum of 35 kHz only 15 years ago. 5,13 Despite all these technological improvements and the wide variety of compounds which can be analysed by NMR, to our knowledge, only one solid-state structural analysis experiment has been performed previously on materials containing transuranic elements (highly radioactive Pu-containing a) Author to whom correspondence should be addressed.…”

Section: Introductionmentioning

confidence: 99%

A nuclear magnetic resonance spectrometer concept for hermetically sealed magic angle spinning investigations on highly toxic, radiotoxic, or air sensitive materials

Martel

Somers

Berkmann

et al. 2013

Review of Scientific Instruments

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A concept to integrate a commercial high-resolution, magic angle spinning nuclear magnetic resonance (MAS-NMR) probe capable of very rapid rotation rates (70 kHz) in a hermetically sealed enclosure for the study of highly radiotoxic materials has been developed and successfully demonstrated. The concept centres on a conventional wide bore (89 mm) solid-state NMR magnet operating with industry standard 54 mm diameter probes designed for narrow bore magnets. Rotor insertion and probe tuning take place within a hermetically enclosed glovebox, which extends into the bore of the magnet, in the space between the probe and the magnet shim system. Oxygen-17 MAS-NMR measurements demonstrate the possibility of obtaining high quality spectra from small sample masses (∼10 mg) of highly radiotoxic material and the need for high spinning speeds to improve the spectral resolution when working with actinides. The large paramagnetic susceptibility arising from actinide paramagnetism in (Th 1−x U x )O 2 solid solutions gives rise to extensive spinning sidebands and poor resolution at 15 kHz, which is dramatically improved at 55 kHz. The first 17 O MAS-NMR measurements on NpO 2+x samples spinning at 55 kHz are also reported. The glovebox approach developed here for radiotoxic materials can be easily adapted to work with other hazardous or even air sensitive materials.

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Chemistry: Breaking the billion-hertz barrier

Cited by 44 publications

References 0 publications

High-Field Superconducting Magnets

High-Field Superconducting Magnets

Ultra-High Field NMR and MRI—The Role of Magnet Technology to Increase Sensitivity and Specificity

A nuclear magnetic resonance spectrometer concept for hermetically sealed magic angle spinning investigations on highly toxic, radiotoxic, or air sensitive materials

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