Journal of magnetic resonance最新文献_第4页

15N optimal control pulses: an efficient approach to enhance heteronuclear-detected NMR experiments at high magnetic fields 15N最优控制脉冲：一种在高磁场下增强异核探测核磁共振实验的有效方法。

IF 1.9 3区化学 Q3 BIOCHEMICAL RESEARCH METHODS

Journal of magnetic resonance

Pub Date : 2025-12-01 Epub Date: 2025-10-04 DOI: 10.1016/j.jmr.2025.107972

Marco Schiavina , David Joseph , Christian Griesinger , Isabella C. Felli , Roberta Pierattelli

Carbon-13 detected Nuclear Magnetic Resonance (NMR) experiments have become a well-established and powerful tool for investigating a wide variety of biomolecular systems, offering unique insights into structure and dynamics. High field NMR spectrometers offer unprecedented resolution, particularly when working at 1.2 GHz, which is crucial in general and particularly important for samples with crowded NMR spectra. However, operating at such high fields introduces new challenges, including the need for efficient spin manipulations across broad frequency ranges while adhering to the power limitations of modern probes. Optimal control (OC) theory offers a powerful framework for designing Radio-Frequency (RF) pulses that achieve desired spin manipulations with high efficiency, even under strict experimental constraints. In this work, we focus on the implementation of OC-designed ¹⁵N pulses to enhance the performance of ¹³C-detected experiments at 1.2 GHz. Specifically, we demonstrate how these pulses improve both excitation bandwidth and signal sensitivity. The approach is validated using a small, well-folded protein and a more challenging intrinsically disordered protein (IDP) dissolved in a high-salt buffer as commonly required for IDPs' stability. Our results show that ¹⁵N OC pulses provide clear benefits across sample types and conditions, confirming their utility as a robust solution for bandwidth-limited NMR experiments at the highest available magnetic fields.

碳-13检测核磁共振（NMR）实验已经成为研究各种生物分子系统的一种成熟而强大的工具，提供了对结构和动力学的独特见解。高场核磁共振光谱仪提供了前所未有的分辨率，特别是当工作在1.2 GHz时，这在一般情况下是至关重要的，对于具有拥挤核磁共振光谱的样品尤其重要。然而，在如此高的磁场下工作带来了新的挑战，包括需要在宽频率范围内进行有效的自旋操作，同时坚持现代探针的功率限制。最优控制（OC）理论为设计射频（RF）脉冲提供了一个强大的框架，即使在严格的实验约束下，也能高效地实现所需的自旋操纵。在这项工作中，我们专注于实现oc设计的15N脉冲，以提高1.2 GHz下13c检测实验的性能。具体来说，我们演示了这些脉冲如何提高激励带宽和信号灵敏度。该方法使用小的、折叠良好的蛋白质和溶解在高盐缓冲液中的更具挑战性的内在无序蛋白（IDP）进行了验证，这通常是IDP稳定性所必需的。我们的研究结果表明，15N OC脉冲在样品类型和条件下都有明显的优势，证实了它们作为在最高可用磁场下带宽有限的核磁共振实验的强大解决方案的实用性。

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引用次数: 0

Measuring reliable electron spin coherence times with dynamical decoupling sequences that use selective mw pulses 使用选择性毫瓦脉冲的动态解耦序列测量可靠的电子自旋相干时间。

IF 1.9 3区化学 Q3 BIOCHEMICAL RESEARCH METHODS

Journal of magnetic resonance

Pub Date : 2025-12-01 Epub Date: 2025-10-06 DOI: 10.1016/j.jmr.2025.107981

George Mitrikas , Rania Giourtsidou

Dynamical decoupling methods like the Carr-Purcell-Meiboom-Gill (CPMG) or XY4- and XY8-based sequences play a key role in the measurement of reliable electron spin coherence times as they help to disentangle different sources of decoherence. Although these methods are mainly evaluated for their robustness and ability to mitigate pulse imperfections, to date little attention has been paid to the selectivity of the microwave pulses (mw), which is a factor that affects the determination of

T_{2}

in two ways: first, unwanted stimulated echoes, which decay with

T_{1}

, overlap with desired refocused echoes, resulting in overestimated values of

T_{2}

. Second, under selective mw excitation, the amplitude of the different refocused echoes shows an additional time decay even in the absence of relaxation processes. Here, we investigate the characteristics of CPMG, XY4 and XY8-based sequences by performing numerical simulations for a two-level spin system. Using the Liouville space representation of the spin state, we introduce relaxation effects in the simulations. We show that our numerical calculations reproduce well all the features of the experimental echoes and allow for the accurate determination of

T_{2}

times without the need to perform tedious phase-cycle protocols to eliminate unwanted signals.

动态解耦方法，如carr - purcell - meiboomm - gill （CPMG）或基于XY4-和xy8的序列，在可靠的电子自旋相干时间测量中起着关键作用，因为它们有助于解开不同的退相干源。虽然这些方法主要是通过鲁棒性和减轻脉冲缺陷的能力来评估的，但迄今为止，人们很少关注微波脉冲的选择性（mw），这是影响T2测定的一个因素，主要有两个方面：首先，不需要的受激发回波，随着T1衰减，与期望的重聚焦回波重叠，导致T2值高估。其次，在选择性毫微米激励下，即使在没有弛豫过程的情况下，不同重聚焦回波的振幅也表现出额外的时间衰减。本文通过对两能级自旋系统的数值模拟，研究了CPMG、XY4和xy8序列的特性。利用自旋态的刘维尔空间表示，我们在模拟中引入了弛豫效应。我们表明，我们的数值计算可以很好地再现实验回波的所有特征，并允许准确确定T2时间，而无需执行繁琐的相位周期协议来消除不需要的信号。

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引用次数: 0

Polychromatic excitation for 1H SABRE polarization transfer in weakly coupled systems at high field 强场弱耦合系统中1H SABRE极化转移的多色激发。

IF 1.9 3区化学 Q3 BIOCHEMICAL RESEARCH METHODS

Journal of magnetic resonance

Pub Date : 2025-12-01 Epub Date: 2025-10-14 DOI: 10.1016/j.jmr.2025.107970

Danil A. Markelov, Alexey S. Kiryutin, Alexandra V. Yurkovskaya

Signal Amplification By Reversible Exchange (SABRE) increases NMR sensitivity using parahydrogen as a source of nuclear spin polarization. In SABRE, the to-be-polarized substrate and dihydrogen in bulk form a transient polarization transfer complex (PTC). This study reports high-field ¹H polarization transfer via SABRE induced by selective polychromatic excitation of ¹H nuclear spins, avoiding a magnetic field-cycling setup and high-power RF pulses. This enables routine SABRE implementation on standard NMR equipment, including MRI scanners. The proposed polychromatic excitation is efficient for the ¹H polarization transfer in the PTCs comprising two weakly coupled hydride ¹H nuclei, i.e. with a large chemical shift difference

\frac{γ}{2 π} B_{0} Δδ ≫ (J)

. We show that in a single type of the PTC, coherent high-field ¹H polarization transfer is driven by double-RF excitation, i.e. applied at two different frequencies simultaneously. In the general case of several PTCs formed by the substrate molecule, the double-RF excitation allows to selectively induce the ¹H polarization transfer in the PTC of interest. To maximize the polarization levels achieved when the substrate forms several types of the PTCs, we propose multi-RF excitation, i.e. applied at more than two ¹H frequencies simultaneously, as a generalization of the double-RF approach. The maximum ¹H signal enhancements at 9.4 T achieved are as follows: −27 for free nicotinamide (−85 for complex-bound), −21 for free 3-methylpyridine (−105 for complex-bound), −23 for pyridine. Remarkably, for all substrates the ¹H signal enhancement exceeds that obtained spontaneously in the high-field: ∼3–9 -fold for the free substrates and ∼10–20-fold for the complex-bound substrates.

可逆交换信号放大（SABRE）利用对氢作为核自旋极化源提高核磁共振灵敏度。在SABRE中，待极化衬底和二氢体形成瞬态极化转移配合物（PTC）。本研究报道了由选择性多色激发1H核自旋通过SABRE诱导的高场1H极化转移，避免了磁场循环设置和高功率RF脉冲。这使得常规的SABRE实现在标准的核磁共振设备，包括MRI扫描仪。所提出的多色激发对于由两个弱耦合氢化物1H核组成的ptc的1H极化转移是有效的，即具有较大的化学位移差γ2πB0Δδ》J。我们发现，在单一类型的PTC中，相干高场1H极化转移是由双射频激励驱动的，即同时在两个不同的频率下施加。在由底物分子形成的几个PTC的一般情况下，双射频激发允许选择性地诱导感兴趣的PTC中的1H极化转移。为了在衬底形成几种类型的ptc时最大限度地提高极化水平，我们提出了多射频激励，即同时在两个以上的1H频率下应用，作为双射频方法的推广。在9.4 T时获得的最大1H信号增强如下：游离烟酰胺-27（配合物结合-85），游离3-甲基吡啶-21（配合物结合-105），吡啶-23。值得注意的是，对于所有底物，1H信号增强都超过了在高场中自发获得的增强：自由底物为~ 3-9倍，配合物结合底物为~ 10-20倍。

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引用次数: 0

On the effects of differential scalar relaxation and chemical exchange in perfect echo NMR spectroscopy of AX spin systems 差标量弛豫和化学交换对AX自旋体系完美回波核磁共振波谱的影响。

IF 1.9 3区化学 Q3 BIOCHEMICAL RESEARCH METHODS

Journal of magnetic resonance

Pub Date : 2025-12-01 Epub Date: 2025-10-11 DOI: 10.1016/j.jmr.2025.107986

Gennady Khirich , Guilherme Dal Poggetto , Matthew P. Augustine

Spin echoes (SE) refocus chemical shift evolution in weakly coupled homonuclear AX spin systems but leave scalar coupling evolution intact, leading to contamination of the in-phase (IP) echo with anti-phase (AP) coherence. In contrast, the so-called perfect echo (PE), which consists of two SEs flanking a central 90° pulse, can minimize the contribution of AP coherence at the echo, with complete refocusing of homonuclear scalar coupling evolution expected in AX systems based on product operator analysis. However, this precludes the consideration of the effects of differential scalar relaxation (DSR) from the interconversion of IP and AP coherences during a PE or a train of PE echoes (PE-CPMG). In this work, the effects of DSR on an AX spin system subject to a PE or PE-CPMG are considered, and the resulting theoretical spin dynamics are discussed. Exact analytical expressions characterizing the IP and AP coherences of each spin as a function of PE time τ_PE are derived for a single PE and show relaxation-induced oscillations (RIOs) superimposed onto the decay envelopes of IP coherences along with the concomitant generation of AP coherence, even when pulses are assumed to be ideal, instantaneous, and on-resonance for both spins. Numerical simulations reveal that oscillations in the decay envelop may persist under a PE-CPMG, and that the relaxation of the IP coherences is sensitive to pulse sequence timing in terms of both the repetition rate

1 / τ_{PE}

and total relaxation period. In general, rapid pulsing quenches the AP components and slows down relaxation, though RIOs persist. Notably, specific values of

1 / τ_{PE}

termed dispersion resonances – result in effectively decoupled and non-oscillatory IP decay profiles. We extend our analysis to an AX system undergoing a global two-state exchange process. In direct analogy to DSR, differences between R_ex,I and R_ex,S – each spin's exchange-induced relaxation enhancements – may induce oscillations in the IP decay profiles and concomitantly generate AP coherence. Moreover, each spin's effective relaxation enhancement is shown to depend on both R_ex,I and R_ex,S. The analysis of the spin dynamics reported here may be of interest in the further understanding, development, and optimization of PE and PE-CPMG-based pulse sequences, particularly those intended to be used for the accurate measurement and quantification of the underlying dynamics of a homonuclear AX systems undergoing chemical exchange.

自旋回波（SE）重新聚焦弱耦合同核AX自旋体系中的化学位移演化，但保持标量耦合演化不变，导致同相（IP）回波受到反相（AP）相干性的污染。相比之下，所谓的完美回波（PE），由两个se侧面的中心90°脉冲组成，可以最大限度地减少回波处AP相干性的贡献，并且基于乘积算子分析的AX系统有望完全重新聚焦同核标量耦合演化。然而，这排除了在PE或PE回波序列（PE- cpmg）期间，IP和AP相干相互转换所产生的微分标量弛豫（DSR）的影响。本文研究了DSR对受PE或PE- cpmg作用的AX自旋体系的影响，并讨论了由此产生的理论自旋动力学。对于单个自旋，导出了每个自旋的IP和AP相干作为PE时间τPE函数的精确解析表达式，并显示了弛豫诱导振荡（RIOs）叠加在IP相干的衰减包络上，伴随着AP相干的产生，即使假设两个自旋的脉冲都是理想的、瞬时的和非共振的。数值模拟结果表明，在PE-CPMG下，衰减包络中的振荡可能持续存在，并且在重复率1/τPE和总弛豫周期方面，IP相干的弛豫对脉冲序列时序都很敏感。一般来说，快速脉冲淬灭AP成分并减缓弛豫，尽管RIOs持续存在。值得注意的是，1/τPE的特定值称为色散共振-导致有效解耦和非振荡的IP衰减剖面。我们将分析扩展到经历全局双状态交换过程的AX系统。直接类比DSR， Rex，I和Rex，S之间的差异-每个自旋的交换诱导弛豫增强-可能会引起激电衰变谱中的振荡，并伴随产生AP相干性。此外，每个自旋的有效弛豫增强都取决于Rex，I和Rex，S。本文报道的自旋动力学分析可能有助于进一步理解、开发和优化基于PE和PE- cpmg的脉冲序列，特别是那些用于进行化学交换的同核AX系统潜在动力学的精确测量和量化的脉冲序列。

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引用次数: 0

An experimental demonstration of the use of a cryogen-free system for high-resolution 1D and 2D solid and liquid state NMR 无低温系统用于高分辨率一维和二维固体和液态核磁共振的实验演示

IF 1.9 3区化学 Q3 BIOCHEMICAL RESEARCH METHODS

Journal of magnetic resonance

Pub Date : 2025-12-01 Epub Date: 2025-10-08 DOI: 10.1016/j.jmr.2025.107985

Eugeny Kryukov , Alexander Karabanov , Denis Langlais , Dinu Iuga , Shashwata Moitra , Jeremy Good

We show that the magnetic field in cryogen-free magnets is stable enough for high-resolution solid-state and liquid-state NMR. The same magnet can be used at different magnetic fields, which can be changed every day without compromising the spectral resolution. The magnet performance was demonstrated on a series of solid-state and liquid-state NMR experiments. Hardware and software correction can additionally be applied to improve the quality of 1D and 2D NMR spectra.

我们证明了无低温磁体中的磁场足够稳定，可以用于高分辨率的固态和液态核磁共振。相同的磁体可以在不同的磁场中使用，可以每天更换而不影响光谱分辨率。在一系列的固态和液态核磁共振实验中证明了该磁体的性能。硬件和软件校正还可以用于提高一维和二维核磁共振谱的质量。

引用次数: 0

Advancing quantitative NMR for high-precision isotopic analysis with rnmrfit 2.0 推进定量核磁共振高精度同位素分析与rnmrfit 2.0。

IF 1.9 3区化学 Q3 BIOCHEMICAL RESEARCH METHODS

Journal of magnetic resonance

Pub Date : 2025-12-01 Epub Date: 2025-10-31 DOI: 10.1016/j.jmr.2025.107991

Kathy Sharon Isaac , Phuong Mai Le , Theodore Street , Akila Wijerathna-Yapa , Stanislav Sokolenko

Quantitative NMR is widely utilized in isotopic ratio measurement for determining the origins and authenticity of chemical compounds. Achieving high precision required for such analyses depends on accurately separating signal from noise, which is essential for reliable quantification of resonance peak areas. In this study, we present rnmrfit 2.0, an NMR peak-fitting tool tailored for high precision isotopic analysis. This new version incorporates semi-global peak fitting with automated peak region selection, achieving greater robustness and computational efficiency than previously reported. The newly developed software was used to explore the impact of two common spectral processing techniques, line broadening and zero filling, as well as the choice of baseline span on peak fitting precision. All three were found to have a significant impact on fit precision, with optimal settings for line broadening and zero filling deviating from what is commonly recommended for 13C spectra, at 1–3 Hz and 0.5–1.0, respectively. Compared to commercial tools including TopSpin and MestReNova, rnmrfit demonstrated superior precision and trueness, achieving precision as low as 0.26% for 2H and 0.16% for 13C. The new version of rnmrfit is available as an open-source executable, offering a scalable solution for isotopic analysis with minimal user input, paving the way for more reliable isotopic quantification.

定量核磁共振广泛应用于同位素比测量，以确定化合物的来源和真实性。实现这种分析所需的高精度取决于准确地将信号与噪声分离，这对于可靠地量化共振峰面积至关重要。在这项研究中，我们提出了ranmrfit 2.0，一个为高精度同位素分析量身定制的核磁共振峰拟合工具。这个新版本结合了半全局峰拟合和自动峰区域选择，实现了比以前报道的更大的鲁棒性和计算效率。利用新开发的软件探讨了两种常用的光谱处理技术——谱线展宽和零填充，以及基线跨度的选择对峰值拟合精度的影响。这三种方法都对拟合精度有显著影响，线宽和零填充的最佳设置分别为1-3 Hz和0.5-1.0，偏离了通常推荐的13C光谱。与TopSpin和MestReNova等商用工具相比，rnmrfit的精度和正确率更高，2H和13C的精度分别低至0.26%和0.16%。新版本的rnmrfit是一个开源的可执行文件，提供了一个可扩展的解决方案，以最少的用户输入进行同位素分析，为更可靠的同位素量化铺平了道路。

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引用次数: 0

Magnetic resonance imaging using a straight wire magnetic field for spatial signal encoding: Imaging verification with 2D experiments and 3D modeling 使用直线磁场进行空间信号编码的磁共振成像：用二维实验和三维建模进行成像验证。

IF 1.9 3区化学 Q3 BIOCHEMICAL RESEARCH METHODS

Journal of magnetic resonance

Pub Date : 2025-12-01 Epub Date: 2025-10-30 DOI: 10.1016/j.jmr.2025.107990

Kaja Tušar , Igor Serša

Spatial encoding in MRI is usually performed using gradient coils that produce a linearly increasing magnetic field B_z in a desired spatial direction such that its gradient is constant. However, it has been shown that spatial encoding in MRI can also be performed with coils that produce nonlinear magnetic fields. In this study, the performance of different types of nonlinear encoding coils, which have a simple design based on the use of a straight wire segment as a building block and a source of a highly nonlinear magnetic field, was experimentally tested in 2D and by simulation in 3D on coils with a nonsymmetric and a symmetric arrangement of these wire segments. All images were reconstructed using our newly presented method, in which the signals are first transformed from the time- to the frequency-domain, yielding a distorted image (spectrum), which is then geometrically and intensity corrected. The quality of the reconstructed images was quantified by comparing them with corresponding reference images obtained with conventional gradient coils. The reconstruction method was accurate for all tested encoding coils and showed that the symmetric coil type produced results that required significantly less corrections compared to the nonsymmetric coil type. Quantitative image quality measurements showed that all encoding coils, despite large differences in the magnetic field of the encoding coils, produce images of similar quality. The results of the study may help advance the design of “gradient” coils towards freer geometries, higher magnetic field gradients or lower inductance and thus faster switching times.

MRI中的空间编码通常使用梯度线圈进行，梯度线圈在期望的空间方向上产生线性增加的磁场Bz，使其梯度恒定。然而，已经证明MRI中的空间编码也可以用产生非线性磁场的线圈进行。在本研究中，不同类型的非线性编码线圈具有基于使用直导线段作为构建块和高度非线性磁场源的简单设计，通过在这些导线段的非对称和对称排列的线圈上进行二维实验测试和三维仿真测试。所有图像都使用我们新提出的方法进行重建，其中信号首先从时域转换到频域，产生失真图像（频谱），然后进行几何和强度校正。通过与常规梯度线圈得到的相应参考图像的比较，量化了重建图像的质量。重建方法对所有测试的编码线圈都是准确的，并且表明对称线圈类型产生的结果与非对称线圈类型相比需要更少的校正。定量图像质量测量表明，尽管编码线圈的磁场差异很大，但所有编码线圈产生的图像质量相似。这项研究的结果可能有助于将“梯度”线圈的设计推向更自由的几何形状、更高的磁场梯度或更低的电感，从而加快开关时间。

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引用次数: 0

Passive shimming performance in 3 T MRI systems: Influence of shim parameters under varying magnet field distributions 3t MRI系统的被动摆振性能：不同磁场分布下摆振参数的影响。

IF 1.9 3区化学 Q3 BIOCHEMICAL RESEARCH METHODS

Journal of magnetic resonance

Pub Date : 2025-12-01 Epub Date: 2025-09-27 DOI: 10.1016/j.jmr.2025.107969

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

This study proposes a simple and computationally efficient method to optimize the structural design parameters of passive shimming slots, aiming to improve magnetic field homogeneity in cryogen-free 3 T/200 mm superconducting magnets used across diverse application environments. The proposed method combines Latin Hypercube Sampling (LHS), utilizing over 300 sampled configurations, with a linear programming (LP)-based optimization framework to explore high-dimensional design spaces while adhering to structural constraints. The method was applied to four distinct magnets, each characterized by unique field inhomogeneity patterns resulting from manufacturing and assembly variations. Through harmonic decomposition, system-specific sensitivities were identified and effectively mitigated using customized passive shimming strategies tailored to each magnet. The optimization process achieved substantial improvements in magnetic field homogeneity, with peak-to-peak (PP) values enhanced to 12.16, 10.04, 27.28, and 54.59 parts per million (ppm) for Magnets 1 to 4, respectively. Correspondingly, the root-mean-square error (RMSE) homogeneity improved to 2.28, 1.98, 5.07, and 9.68 ppm. Furthermore, the magnitudes of all harmonic terms were reduced by 1-2 orders of magnitude, with suppression levels exceeding 90%, while minimizing the use of ferromagnetic materials. The practical feasibility of the proposed strategy was validated on-site: Magnet 1 successfully delivered high-quality animal MRI imaging with excellent signal-to-noise ratios (SNRs), and the remaining magnets are currently undergoing final calibration and delivery. This work presents a robust and scalable optimization framework for precise and resource-efficient passive shimming, offering valuable guidance for future magnet design, customization, and deployment in biomedical and industrial applications.

本研究提出了一种简单且计算效率高的方法来优化被动调光槽的结构设计参数，旨在改善不同应用环境下无低温3t / 200mm超导磁体的磁场均匀性。该方法将拉丁超立方体采样（LHS）与基于线性规划（LP）的优化框架相结合，利用300多个采样配置来探索高维设计空间，同时坚持结构约束。该方法应用于四种不同的磁体，每个磁体都具有独特的磁场不均匀性模式，这是由制造和组装变化引起的。通过谐波分解，确定了系统特定的灵敏度，并使用针对每个磁体量身定制的被动摆振策略有效地减轻了灵敏度。优化过程显著改善了磁场均匀性，磁体1至4的峰对峰（PP）值分别提高到12.16、10.04、27.28和54.59 ppm。相应的，均方根误差（RMSE）均匀性提高到2.28、1.98、5.07和9.68 ppm。此外，所有谐波项的幅度降低了1-2个数量级，抑制水平超过90%，同时最大限度地减少了铁磁材料的使用。现场验证了所提出策略的实际可行性：磁体1成功提供了高质量的动物MRI成像，具有优异的信噪比（SNRs），其余磁体目前正在进行最后的校准和交付。这项工作为精确和资源高效的被动摆振提供了一个强大的可扩展优化框架，为未来磁体的设计、定制和部署在生物医学和工业应用中提供了有价值的指导。

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引用次数: 0

T2–T2∗ relaxation correlation measurement T2-T2 *松弛相关测量。

IF 1.9 3区化学 Q3 BIOCHEMICAL RESEARCH METHODS

Journal of magnetic resonance

Pub Date : 2025-12-01 Epub Date: 2025-10-13 DOI: 10.1016/j.jmr.2025.107987

Dominic O. Couillard, Peiyuan Yan, Mohammad Sadegh Zamiri, Bruce J. Balcom, Benedict Newling

Relaxation and relaxation–diffusion correlation measurements have emerged as essential tools for magnetic resonance of materials. Examples of correlation measurements include the

T_{1}

–

T_{2}

, the

T_{2}

–

D

, and the

T_{1}

–

T_{2}^{*}

variants. In this paper, we describe the implementation and validation of a

T_{2}

–

T_{2}^{*}

relaxation correlation measurement. It is shown that this technique effectively distinguishes microscopic environments dominated by local field inhomogeneity from those dominated by nuclear spin–spin interactions. The method is demonstrated in simulation and in glass bead packs.

弛豫和弛豫扩散相关测量已成为材料磁共振研究的重要工具。相关测量的例子包括T1-T2、T2-D和T1-T2 *变量。在本文中，我们描述了T2-T2 *弛豫相关测量的实现和验证。结果表明，该方法可以有效地区分局部场不均匀性主导的微观环境和核自旋-自旋相互作用主导的微观环境。该方法在仿真和玻璃珠包中得到了验证。

引用次数: 0

NMR of chemical exchange: Revisited 核磁共振化学交换：重访

IF 1.9 3区化学 Q3 BIOCHEMICAL RESEARCH METHODS

Journal of magnetic resonance

Pub Date : 2025-12-01 Epub Date: 2025-09-24 DOI: 10.1016/j.jmr.2025.107968

Janez Stepišnik , Aleš Mohorič

Nuclear magnetic resonance is a powerful technique for examining chemical exchange in liquids by observing how molecular structures evolve. The Carr-Purcell-Meiboom-Gill technique, one of key NMR methods, enables the detection of molecular conformation fluctuations and their influence on observed chemical shifts. This study proposes how NMR measurements of chemical exchange processes can be interpreted using a molecular conformation fluctuation spectrum framework together with chemical Langevin equations. Experimental results obtained for sucrose solutions support the proposed approach, revealing insights into chemical exchange dynamics and spectral line behavior.

核磁共振是一种强大的技术，通过观察分子结构的演变来检测液体中的化学交换。Carr-Purcell-Meiboom-Gill技术是核磁共振的关键方法之一，可以检测分子构象波动及其对观察到的化学位移的影响。本研究提出了如何利用分子构象波动谱框架和化学朗之万方程来解释化学交换过程的核磁共振测量。蔗糖溶液的实验结果支持该方法，揭示了化学交换动力学和谱线行为。

引用次数: 0