Journal of magnetic resonance最新文献_第6页

Revealing the sensitivity of methyl tunneling towards local environment changes with quantum-rotor EPR spectroscopy 利用量子转子EPR光谱揭示甲基隧穿对局部环境变化的敏感性

IF 1.9 3区化学

Journal of magnetic resonance Pub Date : 2025-11-01 Epub Date: 2025-08-26 DOI: 10.1016/j.jmr.2025.107943

Andrea Eggeling, Janne Soetbeer, Gunnar Jeschke

{"title":"Revealing the sensitivity of methyl tunneling towards local environment changes with quantum-rotor EPR spectroscopy","authors":"Andrea Eggeling, Janne Soetbeer, Gunnar Jeschke","doi":"10.1016/j.jmr.2025.107943","DOIUrl":"10.1016/j.jmr.2025.107943","url":null,"abstract":"<div><div>Methyl rotors have potential as local environment probes because their rotation barrier is sensitive to hindering interactions with the nearby surrounding. Quantum-rotor electron paramagnetic resonance (EPR) measurements allow access to this local environment information of the methyl rotor if it is coupled to an electron spin. This is the case for commonly used nitroxide-based spin-labels, where electron spin echo envelope modulation (ESEEM) signals exhibit two contributions on different time scales at low temperatures. The slower decaying contribution is related to matrix-driven nuclear pair ESEEM while the faster contribution originates from methyl tunneling of the electron spin-coupled methyl rotors. The tunneling ESEEM contribution contains local environment information in terms of a distribution of the rotation barrier, which can be quantified using the methyl quantum rotor model. Here, we study the sensitivity of the tunneling behavior towards changes in the rotors’ surrounding by systematically investigating the two-pulse ESEEM signal of nitroxide spin probes containing two pairs of geminal methyl groups in different biologically-relevant matrix compositions. We find that the nitroxide ring structure of these probes strongly impacts the rotation barrier of the observed methyl rotors whereas the matrix surrounding does not affect the underlying rotation barrier distribution. These insights are crucial for designing nitroxide-based spin-labels as local environments probes in combination with site-directed spin-labeling for protein structure elucidation.</div></div>","PeriodicalId":16267,"journal":{"name":"Journal of magnetic resonance","volume":"380 ","pages":"Article 107943"},"PeriodicalIF":1.9,"publicationDate":"2025-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144908820","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Recurrence formula-based automatic gradient eddy current compensation method for a 0.255 T MRI system 基于递推公式的0.255 T MRI自动梯度涡流补偿方法

IF 1.9 3区化学

Journal of magnetic resonance Pub Date : 2025-11-01 Epub Date: 2025-08-18 DOI: 10.1016/j.jmr.2025.107951

Jinhao Liu , Miutian Wang , Wenchen Wang , Yaohui Wang , Wenhui Yang , Weimin Wang , Feng Liu

{"title":"Recurrence formula-based automatic gradient eddy current compensation method for a 0.255 T MRI system","authors":"Jinhao Liu , Miutian Wang , Wenchen Wang , Yaohui Wang , Wenhui Yang , Weimin Wang , Feng Liu","doi":"10.1016/j.jmr.2025.107951","DOIUrl":"10.1016/j.jmr.2025.107951","url":null,"abstract":"<div><div>Gradient coils play a critical role in magnetic resonance imaging (MRI) systems by enabling spatial encoding through generating rapidly switching magnetic fields. However, these time-varying fields induce eddy currents in surrounding conductive structures, leading to gradient field distortions and imaging artifacts. In this study, we propose an automatic eddy current compensation method implemented on a field-programmable gate array (FPGA) platform. The approach employs iterative correction formulas for both linear gradient and <span><math><msub><mrow><mi>B</mi></mrow><mrow><mn>0</mn></mrow></msub></math></span> eddy fields, enabling real-time compensation. To enhance computational efficiency, a novel layout for the pre-emphasis (PE) unit is also introduced. Compared to conventional compensation techniques, the proposed FPGA-based solution offers significant improvements in implementation simplicity and system stability. Experimental results demonstrate that the residual direct- and cross-term eddy current fields are reduced to below 0.02%, equivalent to 4 <span><math><mrow><mi>μT</mi><mo>/</mo><mi>m</mi></mrow></math></span>, for a test gradient of 20 mT/m. Furthermore, the <span><math><msub><mrow><mi>B</mi></mrow><mrow><mn>0</mn></mrow></msub></math></span> eddy field is suppressed to below 0.1 <span><math><mi>μT</mi></math></span> when a <span><math><msub><mrow><mi>B</mi></mrow><mrow><mn>0</mn></mrow></msub></math></span> compensation coil is employed. These improvements effectively reduce ghosting artifacts in multi-slice gradient-echo (GRE) phantom images. The robustness of the method is further validated across various imaging sequences, including T1-weighted (T1w) and T2-weighted (T2w) protocols.</div></div>","PeriodicalId":16267,"journal":{"name":"Journal of magnetic resonance","volume":"380 ","pages":"Article 107951"},"PeriodicalIF":1.9,"publicationDate":"2025-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144922377","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

High-speed, high-memory NMR spectrometer and hyperpolarizer 高速，高存储核磁共振光谱仪和超偏振器

IF 1.9 3区化学

Journal of magnetic resonance Pub Date : 2025-11-01 Epub Date: 2025-08-19 DOI: 10.1016/j.jmr.2025.107952

Leo Joon Il Moon , William Beatrez , Jason Ball , Joan Mercade , Mark Elo , Angad Singh , Emanuel Druga , Ashok Ajoy

{"title":"High-speed, high-memory NMR spectrometer and hyperpolarizer","authors":"Leo Joon Il Moon , William Beatrez , Jason Ball , Joan Mercade , Mark Elo , Angad Singh , Emanuel Druga , Ashok Ajoy","doi":"10.1016/j.jmr.2025.107952","DOIUrl":"10.1016/j.jmr.2025.107952","url":null,"abstract":"<div><div>We report on the development of a novel nuclear magnetic resonance (NMR) spectrometer, incorporating a high-speed, commercially available arbitrary waveform transceiver (AWT) – Tabor Proteus P9484M. The spectrometer is optimized for integrated electron-nuclear spin control and dynamic nuclear polarization (DNP) and leverages the AWT’s rapid sampling rate (9 Gs/s), significant memory capacity (16 GB), and efficient data transfer capabilities (6 Gs/s). These features enable effective NMR transmit–receive operations and electron control for DNP. In particular, the high sampling rates permit NMR pulse synthesis and signal reception directly at the Larmor frequency up to <span><math><mo>∼</mo></math></span>2.7 GHz. This can yield NMR signal-to-noise ratio (SNR) improvements by obviating the need for signal heterodyning. Additionally, the spectrometer features on-board, phase-sensitive detection, enabled by numerically controlled oscillators (NCO); and windowed acquisition can be carried out over extended periods and across millions of pulses, enabling the interrogation of nuclear spin dynamics directly in the rotating frame. The device’s architecture opens up new avenues for NMR pulse control and DNP, including closed-loop feedback control, electron decoupling, 3D spin tracking, and potential applications in quantum sensing.</div></div>","PeriodicalId":16267,"journal":{"name":"Journal of magnetic resonance","volume":"380 ","pages":"Article 107952"},"PeriodicalIF":1.9,"publicationDate":"2025-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144890855","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Flexible and shape-adjustable coaxial capacitor (COCA) coils for ultrahigh field MRI: a comparative analysis with rigid coils 用于超高场MRI的柔性和可调形状同轴电容器（COCA）线圈：与刚性线圈的比较分析

IF 1.9 3区化学

Journal of magnetic resonance Pub Date : 2025-11-01 Epub Date: 2025-08-25 DOI: 10.1016/j.jmr.2025.107955

Ming Lu , Caiwan Sun , Xiaoyu Jiang , Jason E. Moore , John C. Gore , Xinqiang Yan

{"title":"Flexible and shape-adjustable coaxial capacitor (COCA) coils for ultrahigh field MRI: a comparative analysis with rigid coils","authors":"Ming Lu , Caiwan Sun , Xiaoyu Jiang , Jason E. Moore , John C. Gore , Xinqiang Yan","doi":"10.1016/j.jmr.2025.107955","DOIUrl":"10.1016/j.jmr.2025.107955","url":null,"abstract":"<div><div>Flexible RF coils enhance patient comfort and increase filling factors, making them attractive for MRI. However, achieving first-mode resonance at 7 T for large-diameter, flexible coils remains a challenge. We present a coaxial capacitor (COCA) coil, which can be 10 cm in diameter and still operates in the first resonant mode at 298 MHz. Unlike coaxial cable coils that rely on self-resonance, the COCA coil combines ultrasoft Litz wire for inductance with a short coaxial structure for capacitance. Bench tests showed that a 1-capacitor COCA coil provides comparable tuning/matching robustness, effective detuning, and inter-element decoupling performance to conventional rigid coils with three distributed lumped capacitors. MRI acquisitions demonstrated high SNR, especially when the coil conformed to the curvature of the load, with up to 20 % SNR improvement over flat configurations. The coil's ability to retain tuning and matching across different shapes also supports the development of shape-adjustable arrays. By enabling flexible, large-diameter coils to operate in the first resonant mode at ultrahigh fields, the COCA design offers a promising solution for imaging anatomies with complex geometries, such as the shoulder, foot, and spine.</div></div>","PeriodicalId":16267,"journal":{"name":"Journal of magnetic resonance","volume":"380 ","pages":"Article 107955"},"PeriodicalIF":1.9,"publicationDate":"2025-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144912347","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

A wireless bilateral transceiver coil based on volume decoupled resonators for a clinical MR mammography 一种基于体积解耦谐振器的双侧无线收发线圈，用于临床磁共振乳房x光检查

IF 1.9 3区化学

Journal of magnetic resonance Pub Date : 2025-11-01 Epub Date: 2025-08-14 DOI: 10.1016/j.jmr.2025.107941

Pavel Tikhonov , Aleksandr Fedotov , Georgiy Solomakha , Anna Hurshkainen

{"title":"A wireless bilateral transceiver coil based on volume decoupled resonators for a clinical MR mammography","authors":"Pavel Tikhonov , Aleksandr Fedotov , Georgiy Solomakha , Anna Hurshkainen","doi":"10.1016/j.jmr.2025.107941","DOIUrl":"10.1016/j.jmr.2025.107941","url":null,"abstract":"<div><div>Wireless radiofrequency coils offer a valuable low cost solution for various MR applications due to several benefits, such as cable-free connection and compatibility with MR platforms of different vendors. Namely, for the purpose of clinical high-field human breast imaging several wireless transceiver coils are known to the date, those operational principle is based on inductive coupling with a body coil. These coils are commonly consist of a several volume resonators to perform bilateral breast imaging. Due to the electrically close location of volume resonators, strong inductive coupling is observed, resulting in the occurrence of hybrid modes. In principle, MR imaging using one of the hybrid modes is possible provided by the homogeneity of a <span><math><msubsup><mrow><mi>B</mi></mrow><mrow><mn>1</mn></mrow><mrow><mo>+</mo></mrow></msubsup></math></span> distribution. However, the question of influence of volume resonators coupling on wireless coil transmit efficiency and receive sensitivity was not previously studied. By this work, we performed study to understand this issue. The first wireless coil with decoupled resonators is developed, evaluated numerically and experimentally including <em>in vivo</em> study on healthy volunteers. Additionally <em>in vivo</em> images were obtained by a conventional receive array to compare with developed wireless coil. According to the obtained results, transmit efficiency and receive sensitivity of a pair of decoupled Helmholtz resonators of the configuration under study is at least 24% higher than for a pair of the same coupled resonators. <em>In vivo</em> images were also obtained using a six-channel receive array to compare with a developed wireless coil. Comparison with a multi-channel receive array have shown that SNR of the developed wireless coil is 10% lower, while time scanning was increased by 68%.</div></div>","PeriodicalId":16267,"journal":{"name":"Journal of magnetic resonance","volume":"380 ","pages":"Article 107941"},"PeriodicalIF":1.9,"publicationDate":"2025-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144866961","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Corrigendum to “The rate of lactate production from glucose in hearts is not altered by per-deuteration of glucose” [J. Magn. Reson. 284 (2017) 86–93] 心脏中葡萄糖产生乳酸的速率不受葡萄糖氘化的影响[J]。粉剂。理性，284(2017)86-93]。

IF 1.9 3区化学

Journal of magnetic resonance Pub Date : 2025-10-01 Epub Date: 2025-08-18 DOI: 10.1016/j.jmr.2025.107942

Alexander M. Funk , Brian L. Anderson , Xiaodong Wen , Thomas Hever , Chalermchai Khemtong , Zoltan Kovacs , A. Dean Sherry , Craig R. Malloy

引用次数: 0

A mathematical model of NMR transverse relaxation for pore size distribution estimation in porous media 多孔介质中孔径分布估计的核磁共振横向弛豫数学模型

IF 2 3区化学

Journal of magnetic resonance Pub Date : 2025-10-01 Epub Date: 2025-06-23 DOI: 10.1016/j.jmr.2025.107922

S. Morales-Chávez , M.A. Valdez-Grijalva , M.A. Díaz-Viera , E. Lucas-Oliveira , T.J. Bonagamba

{"title":"A mathematical model of NMR transverse relaxation for pore size distribution estimation in porous media","authors":"S. Morales-Chávez , M.A. Valdez-Grijalva , M.A. Díaz-Viera , E. Lucas-Oliveira , T.J. Bonagamba","doi":"10.1016/j.jmr.2025.107922","DOIUrl":"10.1016/j.jmr.2025.107922","url":null,"abstract":"<div><div>Nuclear Magnetic Resonance (NMR) is a widely useful technique for studying porous media. Of particular interest are transverse relaxation times (<span><math><msub><mrow><mi>T</mi></mrow><mrow><mn>2</mn></mrow></msub></math></span>), which are often associated with pore size when surface relaxation is the dominant mechanism. Under specific physical assumptions, a distribution of <span><math><msub><mrow><mi>T</mi></mrow><mrow><mn>2</mn></mrow></msub></math></span> can be used to infer the pore size distribution (PSD). However, in real porous rocks, a combination of diffusion and relaxation mechanisms complicates this interpretation. Despite recent advancements in industrial applications, conventional models frequently rely on simplifying assumptions, particularly when pore size is considered in the fast diffusion regime. This results in the neglect of transverse bulk relaxation (<span><math><msub><mrow><mi>T</mi></mrow><mrow><mn>2</mn><mi>B</mi></mrow></msub></math></span>) effects, leading to underestimations of pore sizes. To address this, numerical methods, particularly the Finite Element Method (FEM), offer flexibility in modeling symmetric geometries while significantly reducing computational complexity. This paper presents a mathematical NMR model and numerical implementation based on FEM to simulate transverse magnetization signals for a PSD, validated with semi-analytical solutions and applied to synthetic and real samples, such as Berea sandstone. Additionally, a change of variable in the Inverse Laplace Transform (ILT) model is introduced for the direct PSD estimation, demonstrating a strong agreement between experimental and simulated data.</div></div>","PeriodicalId":16267,"journal":{"name":"Journal of magnetic resonance","volume":"379 ","pages":"Article 107922"},"PeriodicalIF":2.0,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144588622","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Protecting air/moisture-sensitive samples using perdeuterated paraffin wax for solid-state NMR experiments under magic-angle spinning 用渗透石蜡在魔角纺丝下保护对空气/水分敏感的固体核磁共振实验样品

IF 2 3区化学

Journal of magnetic resonance Pub Date : 2025-10-01 Epub Date: 2025-07-11 DOI: 10.1016/j.jmr.2025.107935

Emma A. Foley , Joseph F. Thuma , Jacob Mayer , Mita Halder , Wenyu Huang , Frédéric A. Perras , Damien B. Culver , Takeshi Kobayashi

{"title":"Protecting air/moisture-sensitive samples using perdeuterated paraffin wax for solid-state NMR experiments under magic-angle spinning","authors":"Emma A. Foley , Joseph F. Thuma , Jacob Mayer , Mita Halder , Wenyu Huang , Frédéric A. Perras , Damien B. Culver , Takeshi Kobayashi","doi":"10.1016/j.jmr.2025.107935","DOIUrl":"10.1016/j.jmr.2025.107935","url":null,"abstract":"<div><div>Solid-state nuclear magnetic resonance (SSNMR) spectroscopy is a powerful technique for materials characterization, yet its application to air- and moisture-sensitive materials is often hindered by the difficulty in maintaining an inert environment during magic-angle spinning (MAS). This is particularly true for fast-MAS rotors that do not generally provide tight seals. Herein, we present a generalizable approach employing perdeuterated paraffin waxes—<em>n</em>-icosane-d42 and <em>c</em>-dodecane-d24—as protective embedding media to analyze sensitive organometallic catalysts using SSNMR. We demonstrate that these waxes significantly slow oxidative degradation under MAS conditions. Weak background <sup>1</sup>H and <sup>13</sup>C NMR signals from the waxes are effectively suppressed using double-quantum filtration and cross-polarization techniques. These findings offer a robust method for expanding the scope of SSNMR to air-sensitive systems, with implications for the structural study of reactive materials and catalysts.</div></div>","PeriodicalId":16267,"journal":{"name":"Journal of magnetic resonance","volume":"379 ","pages":"Article 107935"},"PeriodicalIF":2.0,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144632715","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Broadband excitation of nuclei spin by refocused feedback 重聚焦反馈对原子核自旋的宽带激发

IF 2 3区化学

Journal of magnetic resonance Pub Date : 2025-10-01 Epub Date: 2025-07-16 DOI: 10.1016/j.jmr.2025.107927

Vishesh Kaushik, Navin Khaneja

引用次数: 0

Rapid flow characterization measurements using a modified CPMG measurement with incremented echo times, phase cycling and filtering 快速流动特性测量使用改进的CPMG测量增加回声时间，相位循环和滤波

IF 2 3区化学

Journal of magnetic resonance Pub Date : 2025-10-01 Epub Date: 2025-07-18 DOI: 10.1016/j.jmr.2025.107923

Sebastian J. Richard, Benedict Newling, Bruce J. Balcom

{"title":"Rapid flow characterization measurements using a modified CPMG measurement with incremented echo times, phase cycling and filtering","authors":"Sebastian J. Richard, Benedict Newling, Bruce J. Balcom","doi":"10.1016/j.jmr.2025.107923","DOIUrl":"10.1016/j.jmr.2025.107923","url":null,"abstract":"<div><div>We recently demonstrated a magnetic resonance methodology for measuring and characterizing various pipe flows, using a series of individually-acquired spin echoes at different <span><math><mi>τ</mi></math></span>. The key advantage of our approach lies in the simplicity of the experiment, MR hardware, and data processing. However, acquiring each spin echo separately results in prolonged measurement times. To address this, we employ an echo-train approach to acquire the series of variable <span><math><mi>τ</mi></math></span> spin echoes. By incrementing CPMG echo pulse spacings within the echo train and implementing a four-step phase cycling scheme to suppress coherence pathway effects, we obtain the same echo phase and magnitude response to flow as a function of <span><math><msup><mrow><mi>τ</mi></mrow><mrow><mn>2</mn></mrow></msup></math></span> as in our original method, without requiring individual echo acquisitions. This new approach significantly reduces the number of required experiments, shortening measurement time by a factor of <span><math><mrow><mn>1</mn><mo>/</mo><mi>N</mi></mrow></math></span>, where <span><math><mi>N</mi></math></span> is the number of utilized echoes per echo train. Our phase cycling strategy, combined with incremented pulse spacings, enables <span><math><mrow><mi>N</mi><mo>=</mo><mn>3</mn></mrow></math></span> in our benchtop flow measurement. Validation experiments with Newtonian and shear-thinning fluids confirm that the new echo-train technique yields results consistent with the original approach of acquiring each spin echo separately.</div></div>","PeriodicalId":16267,"journal":{"name":"Journal of magnetic resonance","volume":"379 ","pages":"Article 107923"},"PeriodicalIF":2.0,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144655402","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0