Pub Date : 2026-09-01Epub Date: 2026-08-22DOI: 10.1016/j.jmro.2026.100226
David E. Korenchan, Neha Koonjoo, Sheng Shen, Chetan Dhakan, Scott D. Swanson, Christian T. Farrar, Matthew S. Rosen
Portable low-field MRI is expanding access to imaging, but its diagnostic impact will depend in part on developing quantitative contrast mechanisms that remain informative at ultra-low magnetic field strengths. Magnetization transfer provides one such opportunity by probing interactions between free water and semisolid macromolecular pools, potentially adding molecular specificity to low-field MRI. Quantification of semisolid tissue parameters can further improve disease specificity but requires validated mathematical models applicable to ultra-low magnetic field strengths. Using custom semisolid samples that mimic in vivo brain tissue, we perform some of the first studies of quantitative magnetization transfer spectroscopy at an ultra-low field strength of 6.5 mT, combining saturation-based Z-spectroscopy methods with dynamic water-selective inversion-recovery and simultaneous model fitting to improve semisolid parameter isolation. Our results strongly suggest that the quantitative models developed for high-field magnetic resonance are also applicable at ultra-low field, laying the groundwork for molecularly informed quantitative imaging on future low-field portable MRI systems.
{"title":"Quantitative magnetization transfer model validation at ultra-low field by combining saturation and inversion methods with simultaneous fitting","authors":"David E. Korenchan, Neha Koonjoo, Sheng Shen, Chetan Dhakan, Scott D. Swanson, Christian T. Farrar, Matthew S. Rosen","doi":"10.1016/j.jmro.2026.100226","DOIUrl":"10.1016/j.jmro.2026.100226","url":null,"abstract":"<div><div>Portable low-field MRI is expanding access to imaging, but its diagnostic impact will depend in part on developing quantitative contrast mechanisms that remain informative at ultra-low magnetic field strengths. Magnetization transfer provides one such opportunity by probing interactions between free water and semisolid macromolecular pools, potentially adding molecular specificity to low-field MRI. Quantification of semisolid tissue parameters can further improve disease specificity but requires validated mathematical models applicable to ultra-low magnetic field strengths. Using custom semisolid samples that mimic <em>in vivo</em> brain tissue, we perform some of the first studies of quantitative magnetization transfer spectroscopy at an ultra-low field strength of 6.5 mT, combining saturation-based Z-spectroscopy methods with dynamic water-selective inversion-recovery and simultaneous model fitting to improve semisolid parameter isolation. Our results strongly suggest that the quantitative models developed for high-field magnetic resonance are also applicable at ultra-low field, laying the groundwork for molecularly informed quantitative imaging on future low-field portable MRI systems.</div></div>","PeriodicalId":365,"journal":{"name":"Journal of Magnetic Resonance Open","volume":"28 ","pages":"Article 100226"},"PeriodicalIF":2.2,"publicationDate":"2026-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148854184","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-09-01Epub Date: 2026-08-29DOI: 10.1016/j.jmro.2026.100227
Ming Lu, John C. Gore, Xinqiang Yan
Background
High-density and flexible RF coils in MRI systems have greatly improved patient comfort and enhanced the signal-to-noise ratio (SNR) by better conforming to anatomical shapes and reducing weight. However, the feed boards in flexible coils often occupy large space and require many components, which can limit coil flexibility and integration.
Purpose
To minimize the footprint of the feed board and reduce the number of components while maintaining effective common-mode suppression, this study introduces a compact one-inductor-three-capacitor (LCCC) lumped-element balun design.
Methods
The proposed LCCC balun consists of three capacitors and one inductor. Theoretical analysis based on Kirchhoff’s circuit laws was used to determine the optimal component values, and numerical simulations were conducted to verify the design performance. Prototypes for both 3 T and 7 T MRI were fabricated and experimentally evaluated.
Results
The experimental results demonstrated negligible insertion loss and effective common-mode current suppression across the operating frequencies. The compact design enables easy integration into flexible RF coil arrays. Furthermore, this study explores the potential for dual-tuned applications and alternative topologies, highlighting the versatility of the LCCC balun in advanced MRI RF technologies.
Conclusion
The LCCC lumped-element balun offers a simple, compact, and versatile solution for flexible MRI RF coils. Its small footprint and strong performance make it a promising candidate for next-generation high-density and dual-tuned RF coil arrays.
{"title":"Balun with one inductor and three capacitors for MRI RF coils","authors":"Ming Lu, John C. Gore, Xinqiang Yan","doi":"10.1016/j.jmro.2026.100227","DOIUrl":"10.1016/j.jmro.2026.100227","url":null,"abstract":"<div><h3>Background</h3><div>High-density and flexible RF coils in MRI systems have greatly improved patient comfort and enhanced the signal-to-noise ratio (SNR) by better conforming to anatomical shapes and reducing weight. However, the feed boards in flexible coils often occupy large space and require many components, which can limit coil flexibility and integration.</div></div><div><h3>Purpose</h3><div>To minimize the footprint of the feed board and reduce the number of components while maintaining effective common-mode suppression, this study introduces a compact one-inductor-three-capacitor (LCCC) lumped-element balun design.</div></div><div><h3>Methods</h3><div>The proposed LCCC balun consists of three capacitors and one inductor. Theoretical analysis based on Kirchhoff’s circuit laws was used to determine the optimal component values, and numerical simulations were conducted to verify the design performance. Prototypes for both 3 T and 7 T MRI were fabricated and experimentally evaluated.</div></div><div><h3>Results</h3><div>The experimental results demonstrated negligible insertion loss and effective common-mode current suppression across the operating frequencies. The compact design enables easy integration into flexible RF coil arrays. Furthermore, this study explores the potential for dual-tuned applications and alternative topologies, highlighting the versatility of the LCCC balun in advanced MRI RF technologies.</div></div><div><h3>Conclusion</h3><div>The LCCC lumped-element balun offers a simple, compact, and versatile solution for flexible MRI RF coils. Its small footprint and strong performance make it a promising candidate for next-generation high-density and dual-tuned RF coil arrays.</div></div>","PeriodicalId":365,"journal":{"name":"Journal of Magnetic Resonance Open","volume":"28 ","pages":"Article 100227"},"PeriodicalIF":2.2,"publicationDate":"2026-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148952139","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-06-01Epub Date: 2026-05-09DOI: 10.1016/j.jmro.2026.100220
David Cristea , Utsab Banerjee , Xiaoxun Chen , Julia C. Draeger , Dominik B. Bucher , Aharon Blank
Nitrogen-vacancy (NV) centers in diamond are leading platforms for quantum sensing, yet efficient control of macroscopic ensembles remains challenging. While resonant structures offer high microwave-to-magnetic-field conversion factor (Cp), their narrow bandwidths typically preclude simultaneous addressing of NV transitions and co-located g∼2 paramagnetic species, which are separated by ∼2.87 GHz at X-band. By enabling concurrent pulsed control of NVs and bath electron spins, one can facilitate advanced applications such as spin-bath driving and NV-assisted dynamic nuclear polarization in ensemble samples. We present a compact dual-frequency dielectric resonator designed to resolve this limitation by co-exciting the TE01δ mode (∼9 GHz) and the HEM12δ mode (∼11.8 GHz) within a high-permittivity (ε' ∼ 80) ceramic ring. This architecture concentrates magnetic fields in a shared sample volume just above the resonator surface while maintaining essential optical access and minimizing electric-field-induced heating. Experimental characterization demonstrates resonance frequencies of 8.78 GHz (Q ∼ 237) and 11.41 GHz (Q ∼ 64), with fine-tuning capabilities. Electron spin resonance (ESR) measurements on P1-rich diamond yielded microwave magnetic field, B1, conversion factors of Cp ∼3.6 and ∼1.2 G/√W, for the respective modes. Additional validation via optically detected magnetic resonance (ODMR) confirmed high-fidelity Rabi oscillations for the low frequency mode (the NV transition |0>↔|-1>) π-pulse durations of ∼ 24 ns, using a peak microwave power of 63 W.
{"title":"Dual-frequency dielectric resonator for combined magnetic resonance of g∼2 paramagnetic species and diamond NV centers","authors":"David Cristea , Utsab Banerjee , Xiaoxun Chen , Julia C. Draeger , Dominik B. Bucher , Aharon Blank","doi":"10.1016/j.jmro.2026.100220","DOIUrl":"10.1016/j.jmro.2026.100220","url":null,"abstract":"<div><div>Nitrogen-vacancy (NV) centers in diamond are leading platforms for quantum sensing, yet efficient control of macroscopic ensembles remains challenging. While resonant structures offer high microwave-to-magnetic-field conversion factor (<em>C</em><sub>p</sub>), their narrow bandwidths typically preclude simultaneous addressing of NV transitions and co-located g∼2 paramagnetic species, which are separated by ∼2.87 GHz at X-band. By enabling concurrent pulsed control of NVs and bath electron spins, one can facilitate advanced applications such as spin-bath driving and NV-assisted dynamic nuclear polarization in ensemble samples. We present a compact dual-frequency dielectric resonator designed to resolve this limitation by co-exciting the TE<sub>01δ</sub> mode (∼9 GHz) and the HEM<sub>12δ</sub> mode (∼11.8 GHz) within a high-permittivity (<em>ε</em>' ∼ 80) ceramic ring. This architecture concentrates magnetic fields in a shared sample volume just above the resonator surface while maintaining essential optical access and minimizing electric-field-induced heating. Experimental characterization demonstrates resonance frequencies of 8.78 GHz (<em>Q ∼</em> 237) and 11.41 GHz (<em>Q</em> ∼ 64), with fine-tuning capabilities. Electron spin resonance (ESR) measurements on P1-rich diamond yielded microwave magnetic field, <em>B</em><sub>1</sub>, conversion factors of <em>C</em><sub>p</sub> ∼3.6 and ∼1.2 G/√W, for the respective modes. Additional validation via optically detected magnetic resonance (ODMR) confirmed high-fidelity Rabi oscillations for the low frequency mode (the NV transition |0>↔|-1>) π-pulse durations of ∼ 24 ns, using a peak microwave power of 63 W.</div></div>","PeriodicalId":365,"journal":{"name":"Journal of Magnetic Resonance Open","volume":"27 ","pages":"Article 100220"},"PeriodicalIF":2.624,"publicationDate":"2026-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148186786","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-06-01Epub Date: 2026-05-20DOI: 10.1016/j.jmro.2026.100223
Jesse D. Roberts Jr. , Sharron X. Lin , Matthew S. Rosen , Yiqiao Song
Bronchopulmonary dysplasia (BPD) is a major complication of premature birth and a leading cause of morbidity, mortality, and health care utilization. Susceptibility to BPD is strongly linked to the developmental state of the peripheral lung and decreases sharply with the onset of alveolarization, a postnatal phase characterized by rapid increases in tissue microstructural complexity and extracellular matrix assembly. While these processes are well described biologically, their influence on nuclear spin relaxation behavior—particularly at low magnetic field—has not been established.
Here, we hypothesized that the onset and progression of alveolarization produce distinct and measurable changes in hydrogen spin–lattice (T₁) and spin–spin (T₂) relaxation times reflecting evolving tissue composition, water–macromolecule interactions, and microstructural organization. Using a novel and compact low-field ¹H NMR system, we measured T₁ and T₂ in peripheral lung tissues obtained from mouse pups spanning pre- and post-alveolarization stages, as well as from mature adult lungs.
We observed robust, reproducible, and development-dependent reductions in both T₁ and T₂ that coincided with the emergence and maturation of alveolar structures. Relaxation metrics distinguished pre- from post-alveolarization lung tissue, exhibited stable coupling between T₁ and T₂ across development, and showed no detectable inter-lobe variability, indicating sensitivity to intrinsic developmental remodeling. Together, these findings establish low-field NMR relaxometry as a sensitive probe of lung developmental states and provide a framework for interpreting relaxation contrast in heterogeneous, aerated tissues. Our results support continued development of portable relaxometry systems for noninvasive assessment of lung maturation and early stratification of BPD risk. (250/250 words allowable)
{"title":"Low-magnetic-field NMR relaxometry detects alveolarization in the developing lung","authors":"Jesse D. Roberts Jr. , Sharron X. Lin , Matthew S. Rosen , Yiqiao Song","doi":"10.1016/j.jmro.2026.100223","DOIUrl":"10.1016/j.jmro.2026.100223","url":null,"abstract":"<div><div>Bronchopulmonary dysplasia (BPD) is a major complication of premature birth and a leading cause of morbidity, mortality, and health care utilization. Susceptibility to BPD is strongly linked to the developmental state of the peripheral lung and decreases sharply with the onset of alveolarization, a postnatal phase characterized by rapid increases in tissue microstructural complexity and extracellular matrix assembly. While these processes are well described biologically, their influence on nuclear spin relaxation behavior—particularly at low magnetic field—has not been established.</div><div>Here, we hypothesized that the onset and progression of alveolarization produce distinct and measurable changes in hydrogen spin–lattice (T₁) and spin–spin (T₂) relaxation times reflecting evolving tissue composition, water–macromolecule interactions, and microstructural organization. Using a novel and compact low-field ¹H NMR system, we measured T₁ and T₂ in peripheral lung tissues obtained from mouse pups spanning pre- and post-alveolarization stages, as well as from mature adult lungs.</div><div>We observed robust, reproducible, and development-dependent reductions in both T₁ and T₂ that coincided with the emergence and maturation of alveolar structures. Relaxation metrics distinguished pre- from post-alveolarization lung tissue, exhibited stable coupling between T₁ and T₂ across development, and showed no detectable inter-lobe variability, indicating sensitivity to intrinsic developmental remodeling. Together, these findings establish low-field NMR relaxometry as a sensitive probe of lung developmental states and provide a framework for interpreting relaxation contrast in heterogeneous, aerated tissues. Our results support continued development of portable relaxometry systems for noninvasive assessment of lung maturation and early stratification of BPD risk. (250/250 words allowable)</div></div>","PeriodicalId":365,"journal":{"name":"Journal of Magnetic Resonance Open","volume":"27 ","pages":"Article 100223"},"PeriodicalIF":2.624,"publicationDate":"2026-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148186787","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-03-01Epub Date: 2025-12-16DOI: 10.1016/j.jmro.2025.100214
Gordon E. Sarty
We have been developing Magnetic Resonance Imaging (MRI) technology that is suitable for imaging astronauts in space for a little more than a decade. The technology may be classified as “gradient-free” MRI and works by using Radio Frequency (RF) spatial phase encoding instead of the usual magnetic field gradient mediated spatial frequency encoding. Here a progress report is given along with an outline of where and how MRI can be used in future space flight. To date we have completed several design concept studies for the Canadian Space Agency (CSA), have flown a prototype in zero-g and have developed an approach that can realize the CSA’s Health Beyond vision for the MRI technology. The first applications for MRI in space will be for research on the effects of space flight on the human body, especially that of interplanetary radiation. Following that, MRI can be a central part of an integrated spacecraft medical system and used for diagnostic medical purposes.
{"title":"The development of Magnetic Resonance Imaging (MRI) technology for use in space—A progress report","authors":"Gordon E. Sarty","doi":"10.1016/j.jmro.2025.100214","DOIUrl":"10.1016/j.jmro.2025.100214","url":null,"abstract":"<div><div>We have been developing Magnetic Resonance Imaging (MRI) technology that is suitable for imaging astronauts in space for a little more than a decade. The technology may be classified as “gradient-free” MRI and works by using Radio Frequency (RF) spatial phase encoding instead of the usual magnetic field gradient mediated spatial frequency encoding. Here a progress report is given along with an outline of where and how MRI can be used in future space flight. To date we have completed several design concept studies for the Canadian Space Agency (CSA), have flown a prototype in zero-g and have developed an approach that can realize the CSA’s Health Beyond vision for the MRI technology. The first applications for MRI in space will be for research on the effects of space flight on the human body, especially that of interplanetary radiation. Following that, MRI can be a central part of an integrated spacecraft medical system and used for diagnostic medical purposes.</div></div>","PeriodicalId":365,"journal":{"name":"Journal of Magnetic Resonance Open","volume":"26 ","pages":"Article 100214"},"PeriodicalIF":2.624,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145898069","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-03-01Epub Date: 2025-12-19DOI: 10.1016/j.jmro.2025.100213
Johanna Tratz, Markus Matz, Manfred Wilhelm
In NMR spectroscopy, samples are usually dissolved in deuterated solvents to avoid overlap of small analyte signals with large, protonated solvent signals. However, for reasons such as cost and widespread use, using deuterated solvents is impractical, e.g., for on-flow NMR applications, since large volumes of solvent are required. This study compares six different solvent suppression techniques: PRESATuration (PRESAT), Water suppression Enhanced through T1 effects (WET), Pulsed Gradient STimulated Echo (PGSTE), 1-pulse-spoil, simple solvent subtraction, and a newly developed post-acquisition suppression method named Solvent Attenuation by Fourier Elimination (SAFE). The SAFE method is based on alternating measurements of the sample solution and the pure solvent 2n times, followed by a fast Fourier transform to eliminate the solvent signals, which are constant in the first approximation. The different solvent suppression methods were compared alone and in several combinations to determine their optimum suppression efficiency. The suppression was quantified by evaluating the Analyte-to-Solvent Ratio normalized to the unsuppressed 1H reference spectrum (ASRnorm). Furthermore, a comparison was made between the methods concerning their suitability for polymer solutions of varying molar masses, quantification towards measurement time efficiency, repeatability, and intermediate precision. The PGSTE-SAFE combination proved to be the most efficient method for polymer samples, achieving an ASRnorm of about 47,000. The applicability of solvent suppression methods in flow-based setups was also assessed by investigating polystyrenes in non-deuterated solvents. WET, PGSTE, and a WET-PGSTE combination were applied in online Size Exclusion Chromatography-NMR (SECNMR) to demonstrate their potential for efficient solvent suppression in this context.
{"title":"Comparison of different solvent suppression techniques for polymer characterization with a 90 MHz benchtop spectrometer","authors":"Johanna Tratz, Markus Matz, Manfred Wilhelm","doi":"10.1016/j.jmro.2025.100213","DOIUrl":"10.1016/j.jmro.2025.100213","url":null,"abstract":"<div><div>In NMR spectroscopy, samples are usually dissolved in deuterated solvents to avoid overlap of small analyte signals with large, protonated solvent signals. However, for reasons such as cost and widespread use, using deuterated solvents is impractical, e.g., for on-flow NMR applications, since large volumes of solvent are required. This study compares six different solvent suppression techniques: PRESATuration (PRESAT), Water suppression Enhanced through <em>T</em><sub>1</sub> effects (WET), Pulsed Gradient STimulated Echo (PGSTE), 1-pulse-spoil, simple solvent subtraction, and a newly developed post-acquisition suppression method named Solvent Attenuation by Fourier Elimination (SAFE). The SAFE method is based on alternating measurements of the sample solution and the pure solvent 2<sup>n</sup> times, followed by a fast Fourier transform to eliminate the solvent signals, which are constant in the first approximation. The different solvent suppression methods were compared alone and in several combinations to determine their optimum suppression efficiency. The suppression was quantified by evaluating the Analyte-to-Solvent Ratio normalized to the unsuppressed <sup>1</sup>H reference spectrum (ASR<sub>norm</sub>). Furthermore, a comparison was made between the methods concerning their suitability for polymer solutions of varying molar masses, quantification towards measurement time efficiency, repeatability, and intermediate precision. The PGSTE-SAFE combination proved to be the most efficient method for polymer samples, achieving an ASR<sub>norm</sub> of about 47,000. The applicability of solvent suppression methods in flow-based setups was also assessed by investigating polystyrenes in non-deuterated solvents. WET, PGSTE, and a WET-PGSTE combination were applied in online Size Exclusion Chromatography-NMR (SEC<img>NMR) to demonstrate their potential for efficient solvent suppression in this context.</div></div>","PeriodicalId":365,"journal":{"name":"Journal of Magnetic Resonance Open","volume":"26 ","pages":"Article 100213"},"PeriodicalIF":2.624,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145898105","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-03-01Epub Date: 2026-02-09DOI: 10.1016/j.jmro.2026.100215
Hanna Wili , Nicholas Alaniva , Snædís Björgvinsdóttir, Alexander B. Barnes
Magic-angle spinning (MAS) partially averages anisotropic NMR interactions to improve spectral resolution of solid samples. MAS requires the sample to be spun precisely about an angle of 54.74° with respect to the magnetic field. This technique introduces components within MAS NMR radiofrequency probes that are distinguishable from their solution-state counterparts - most notably, a stator that spins and sets the angle of spinning axis. Here, we present an MAS stator that spins and pneumatically sets the spinning axis angle of a 6 mm spherical rotor (65µL sample volume) while inside a 10 mm solution-state NMR tube. 79Br experiments are used to verify the pneumatic adjustment and stability of the spinning angle, with 79Br spinning echoes from KBr observed out to 8 ms. Utility for solid state MAS NMR is then demonstrated by a 31P experiment of a proton-free inorganic phosphate, K4P2O7. Although this stator is applied here as an MAS insert that expands the utility of a solution-state probe, its compact design is advantageous for any spinning experiments in a restricted space.
{"title":"MAS NMR with a spherical rotor in a 10 mm NMR tube","authors":"Hanna Wili , Nicholas Alaniva , Snædís Björgvinsdóttir, Alexander B. Barnes","doi":"10.1016/j.jmro.2026.100215","DOIUrl":"10.1016/j.jmro.2026.100215","url":null,"abstract":"<div><div>Magic-angle spinning (MAS) partially averages anisotropic NMR interactions to improve spectral resolution of solid samples. MAS requires the sample to be spun precisely about an angle of 54.74° with respect to the magnetic field. This technique introduces components within MAS NMR radiofrequency probes that are distinguishable from their solution-state counterparts - most notably, a stator that spins and sets the angle of spinning axis. Here, we present an MAS stator that spins and pneumatically sets the spinning axis angle of a 6 mm spherical rotor (65µL sample volume) while inside a 10 mm solution-state NMR tube. <sup>79</sup>Br experiments are used to verify the pneumatic adjustment and stability of the spinning angle, with <sup>79</sup>Br spinning echoes from KBr observed out to 8 ms. Utility for solid state MAS NMR is then demonstrated by a <sup>31</sup>P experiment of a proton-free inorganic phosphate, K<sub>4</sub>P<sub>2</sub>O<sub>7</sub>. Although this stator is applied here as an MAS insert that expands the utility of a solution-state probe, its compact design is advantageous for any spinning experiments in a restricted space.</div></div>","PeriodicalId":365,"journal":{"name":"Journal of Magnetic Resonance Open","volume":"26 ","pages":"Article 100215"},"PeriodicalIF":2.624,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147421230","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-03-01Epub Date: 2026-02-10DOI: 10.1016/j.jmro.2026.100216
Jasmin Schönzart , Alexander B. Barnes
We propose small and simplified magnets above 50 Tesla for wide dissemination to the NMR community. High temperature superconductor (HTS) with high current densities readily provide a viable path to a new generation of magnets for NMR which are smaller, better, and cheaper. A key innovation we foresee is the reduction of NMR magnet mandrels (a.k.a. winding bobbins) from typically employed diameter of >100 mm to smaller than 15 mm. Conventional NMR probes are far too large in diameter to fit into such small magnet bores and are unfavorably long due to the distance from the homogenous region of the magnet to the edge of the bore. Instead, we envision narrow (<10 mm diameter) and short (<20 mm length) extensions of the probe inside the magnet bore. Additionally, interior to the bore will be a stator housing a magic angle spinning (MAS) sphere. Exterior to the bore, radio frequency circuity and other probe component dimensions will therefore be unrestricted, and uncoupled, from magnet geometry. Moreover, MAS spheres together with narrow bore HTS magnets will be the keystone technology enabling solid state NMR above 50 Tesla. We also consider effects of magnetic susceptibility and symmetry of components near the sample to ultimately acquire high-resolution NMR spectra. Possible avenues for thermal isolation between the magnet and sample are considered for experiments in a temperature range of 4 to 400 Kelvin. These magnets will be small enough to fit in the palm of your hand. Shrinking the overall size of NMR magnets will improve dissemination as the production costs and required laboratory space will be significantly smaller. The small magnets will have 5 Gauss radii of less than a meter without active shielding—making them easier to site and easier to manufacture. With this new paradigm of enhanced technology, NMR spectroscopists will be well-positioned to push the frontiers of science ahead in the future.
{"title":"Miniaturized magnets for NMR above 50 tesla","authors":"Jasmin Schönzart , Alexander B. Barnes","doi":"10.1016/j.jmro.2026.100216","DOIUrl":"10.1016/j.jmro.2026.100216","url":null,"abstract":"<div><div>We propose small and simplified magnets above 50 Tesla for wide dissemination to the NMR community. High temperature superconductor (HTS) with high current densities readily provide a viable path to a new generation of magnets for NMR which are smaller, better, and cheaper. A key innovation we foresee is the reduction of NMR magnet mandrels (a.k.a. winding bobbins) from typically employed diameter of >100 mm to smaller than 15 mm. Conventional NMR probes are far too large in diameter to fit into such small magnet bores and are unfavorably long due to the distance from the homogenous region of the magnet to the edge of the bore. Instead, we envision narrow (<10 mm diameter) and short (<20 mm length) extensions of the probe inside the magnet bore. Additionally, interior to the bore will be a stator housing a magic angle spinning (MAS) sphere. Exterior to the bore, radio frequency circuity and other probe component dimensions will therefore be unrestricted, and uncoupled, from magnet geometry. Moreover, MAS spheres together with narrow bore HTS magnets will be the keystone technology enabling solid state NMR above 50 Tesla. We also consider effects of magnetic susceptibility and symmetry of components near the sample to ultimately acquire high-resolution NMR spectra. Possible avenues for thermal isolation between the magnet and sample are considered for experiments in a temperature range of 4 to 400 Kelvin. These magnets will be small enough to fit in the palm of your hand. Shrinking the overall size of NMR magnets will improve dissemination as the production costs and required laboratory space will be significantly smaller. The small magnets will have 5 Gauss radii of less than a meter without active shielding—making them easier to site and easier to manufacture. With this new paradigm of enhanced technology, NMR spectroscopists will be well-positioned to push the frontiers of science ahead in the future.</div></div>","PeriodicalId":365,"journal":{"name":"Journal of Magnetic Resonance Open","volume":"26 ","pages":"Article 100216"},"PeriodicalIF":2.624,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147421229","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-01Epub Date: 2025-11-01DOI: 10.1016/j.jmro.2025.100212
Joseph P. Hornak , James D. Phillips , Arash Fereidouni
Field-programmable gate array (FPGA) enabled direct digital detection (DDD) at higher frequencies is becoming increasingly available and popular due to the high-speed real-time signal processing. Consequently, it is opening up new possibilities for digital rather than analog demodulation, filtering, quadrature detection, and general signal processing that can reduce the spectrometer noise associated with thermal drift, aging, and layout of the equivalent analog detection chain. This article presents the result of a comparison of the low-frequency electron paramagnetic resonance (LFEPR) signal-to-noise ratio for a DPPH standard on the electron paramagnetic resonance (EPR) mobile universal surface explorer (MOUSE) by two signal detection schemes. The first utilized the classic analog detection and demodulation scheme of a LFEPR spectrometer and the second utilized the Zurich Instruments ultra-high frequency lock-in (UHFLI) amplifier, which replaces most of the analog components in the LFEPR spectrometer. The UHFLI spectrometer configuration improved the signal-to-noise ratio by a factor of two, reduced the baseline drift to one eighteenth, reduced the instrument volume by 70 %, and reduced the instrument weight by 50 % compared to the values with the classic analog system.
{"title":"Improving a low frequency EPR spectrometer using field-programmable gate array enabled direct digital detection","authors":"Joseph P. Hornak , James D. Phillips , Arash Fereidouni","doi":"10.1016/j.jmro.2025.100212","DOIUrl":"10.1016/j.jmro.2025.100212","url":null,"abstract":"<div><div>Field-programmable gate array (FPGA) enabled direct digital detection (DDD) at higher frequencies is becoming increasingly available and popular due to the high-speed real-time signal processing. Consequently, it is opening up new possibilities for digital rather than analog demodulation, filtering, quadrature detection, and general signal processing that can reduce the spectrometer noise associated with thermal drift, aging, and layout of the equivalent analog detection chain. This article presents the result of a comparison of the low-frequency electron paramagnetic resonance (LFEPR) signal-to-noise ratio for a DPPH standard on the electron paramagnetic resonance (EPR) mobile universal surface explorer (MOUSE) by two signal detection schemes. The first utilized the classic analog detection and demodulation scheme of a LFEPR spectrometer and the second utilized the Zurich Instruments ultra-high frequency lock-in (UHFLI) amplifier, which replaces most of the analog components in the LFEPR spectrometer. The UHFLI spectrometer configuration improved the signal-to-noise ratio by a factor of two, reduced the baseline drift to one eighteenth, reduced the instrument volume by 70 %, and reduced the instrument weight by 50 % compared to the values with the classic analog system.</div></div>","PeriodicalId":365,"journal":{"name":"Journal of Magnetic Resonance Open","volume":"25 ","pages":"Article 100212"},"PeriodicalIF":2.624,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145463159","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-01Epub Date: 2025-09-04DOI: 10.1016/j.jmro.2025.100210
Matthew C. Young , Sarah L. Codd , Joseph D. Seymour
Plant fibers are of current interest in biocomposites and known hydrophilicity of plant fibers, e.g. corn stalk pith and hemp stalk, require enhanced understanding of water impacts on fiber structure. Water distribution during hydration in these fibers is compared to fibrous cellulose media using nuclear magnetic resonance (NMR) relaxometry and diffusometry. Measurements were made every 6 h from h, or until equilibrium. NMR measured bound, intermediate bound and macropore water populations at two water mass hydrations. NMR diffusometry measured diffusion coefficients of mobile water populations in each material. The diffusion coefficient was acquired as a function of molecular migration time to detect restricted diffusion. behavior indicated increased interpore connectivity in highly saturated hemp, versus swollen pores saturated pith. values were fit for surface to volume ratio to determine average pore radius as a function of hydration. values were paired to distributions to provide an effective average transverse magnetic surface relaxivity throughout hydration, which is then used to rescale distributions as pore size distributions. Bound water was found in pores m, semi-bound water in pores from m and macropore water in pores from m, in agreement with prior literature.
{"title":"Long-term water migration in hydrated corn stalk pith and hemp stalk by 250 MHz NMR relaxometry and diffusometry","authors":"Matthew C. Young , Sarah L. Codd , Joseph D. Seymour","doi":"10.1016/j.jmro.2025.100210","DOIUrl":"10.1016/j.jmro.2025.100210","url":null,"abstract":"<div><div>Plant fibers are of current interest in biocomposites and known hydrophilicity of plant fibers, e.g. corn stalk pith and hemp stalk, require enhanced understanding of water impacts on fiber structure. Water distribution during hydration in these fibers is compared to fibrous cellulose media using nuclear magnetic resonance (NMR) <span><math><msub><mrow><mi>T</mi></mrow><mrow><mn>2</mn></mrow></msub></math></span> relaxometry and diffusometry. Measurements were made every 6 h from <span><math><mrow><mn>3</mn><mtext>–</mtext><mn>237</mn></mrow></math></span> h, or until equilibrium. NMR <span><math><msub><mrow><mi>T</mi></mrow><mrow><mn>2</mn></mrow></msub></math></span> measured bound, intermediate bound and macropore water populations at two water mass hydrations. NMR diffusometry measured diffusion coefficients <span><math><mi>D</mi></math></span> of mobile water populations in each material. The diffusion coefficient <span><math><mi>D</mi></math></span> was acquired as a function of molecular migration time <span><math><mi>Δ</mi></math></span> to detect restricted diffusion. <span><math><mrow><mi>D</mi><mrow><mo>(</mo><mi>Δ</mi><mo>)</mo></mrow></mrow></math></span> behavior indicated increased interpore connectivity in highly saturated hemp, versus swollen pores saturated pith. <span><math><mrow><mi>D</mi><mrow><mo>(</mo><mi>Δ</mi><mo>)</mo></mrow></mrow></math></span> values were fit for surface to volume ratio <span><math><mrow><mi>S</mi><mo>/</mo><mi>V</mi></mrow></math></span> to determine average pore radius <span><math><mi>r</mi></math></span> as a function of hydration. <span><math><mrow><mi>S</mi><mo>/</mo><mi>V</mi></mrow></math></span> values were paired to <span><math><msub><mrow><mi>T</mi></mrow><mrow><mn>2</mn></mrow></msub></math></span> distributions to provide an effective average transverse magnetic surface relaxivity <span><math><msub><mrow><mover><mrow><mi>ρ</mi></mrow><mrow><mo>̄</mo></mrow></mover></mrow><mrow><mn>2</mn></mrow></msub></math></span> throughout hydration, which is then used to rescale <span><math><msub><mrow><mi>T</mi></mrow><mrow><mn>2</mn></mrow></msub></math></span> distributions as pore size distributions. Bound water was found in pores <span><math><mrow><mo><</mo><mn>1</mn><mspace></mspace><mi>μ</mi></mrow></math></span>m, semi-bound water in pores from <span><math><mrow><mn>1</mn><mtext>–</mtext><mn>30</mn><mspace></mspace><mi>μ</mi></mrow></math></span>m and macropore water in pores from <span><math><mrow><mn>30</mn><mtext>–</mtext><mn>300</mn><mspace></mspace><mi>μ</mi></mrow></math></span>m, in agreement with prior literature.</div></div>","PeriodicalId":365,"journal":{"name":"Journal of Magnetic Resonance Open","volume":"25 ","pages":"Article 100210"},"PeriodicalIF":2.624,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145047896","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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