Journal of magnetic resonance最新文献

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Gradient coil design for a 0.23 T NICU MRI system using an improved two-step Target-Field Method with enhanced linearity and compact design 采用改进的两步靶场法设计0.23 T NICU MRI系统的梯度线圈,增强了线性和紧凑的设计
IF 2 3区 化学
Journal of magnetic resonance Pub Date : 2025-10-01 Epub Date: 2025-07-24 DOI: 10.1016/j.jmr.2025.107936
Jinhao Liu , Miutian Wang , Wenchen Wang , Yaohui Wang , Weimin Wang , Feng Liu
{"title":"Gradient coil design for a 0.23 T NICU MRI system using an improved two-step Target-Field Method with enhanced linearity and compact design","authors":"Jinhao Liu ,&nbsp;Miutian Wang ,&nbsp;Wenchen Wang ,&nbsp;Yaohui Wang ,&nbsp;Weimin Wang ,&nbsp;Feng Liu","doi":"10.1016/j.jmr.2025.107936","DOIUrl":"10.1016/j.jmr.2025.107936","url":null,"abstract":"<div><div>This study presents an optimized gradient coil design for a miniature 0.23 T MRI system, aimed at improving absolute and relative magnetic field linearity while accommodating various gradient thicknesses. The design uses a two-step optimization approach: the first step uses Tikhonov regularization to solve a linear problem, providing a stable solution, and the second step refines the solution through nonlinear constrained optimization to further enhance field linearity. An explicit objective function for the inductance matrix of biplanar gradient coils is simplified to enhance computational efficiency. Validation through MATLAB and COMSOL finite element analysis showed excellent performance. Imaging experiments were conducted on small animals (cats and dogs, whose sizes are similar to neonates) while awaiting ethical approval for human neonatal studies. Results demonstrated that all gradient coils achieved absolute and relative linearity errors below 5%. Cubic phantom scans showed slight displacement at the edges, but the structured phantom MRI lines align precisely with the physical markers, indicating negligible geometric distortion. The shield design maintained Z-leakage fields below 5 Gauss, with eddy current compensation achieving a 90% reduction (residual X/Y-gradient <span><math><mo>&lt;</mo></math></span> 0.05%, Z-gradient <span><math><mo>&lt;</mo></math></span> 0.20%). T1 and T2-weighted images depicted clear brain structures, while FLAIR and STIR sequences effectively highlighted tissue changes. The proposed gradient coil design method significantly improves absolute and relative linearity while accommodating various gradient thicknesses, demonstrating strong resistance to interference and broad applicability. The comprehensive design-to-manufacturing process ensures optimal parameter selection, resulting in high-quality imaging across multiple MRI sequences. This design demonstrates strong potential for precise <em>in-vivo</em> brain imaging in further NICU applications.</div></div>","PeriodicalId":16267,"journal":{"name":"Journal of magnetic resonance","volume":"379 ","pages":"Article 107936"},"PeriodicalIF":2.0,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144704306","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
Removing magnetic field noise from NMR spectra: Reference deconvolution revisited 从核磁共振波谱中去除磁场噪声:参考反褶积
IF 1.9 3区 化学
Journal of magnetic resonance Pub Date : 2025-10-01 Epub Date: 2025-07-28 DOI: 10.1016/j.jmr.2025.107937
Alexander Karabanov , Eugeny Kryukov , Gareth Morris , Jeremy Good
{"title":"Removing magnetic field noise from NMR spectra: Reference deconvolution revisited","authors":"Alexander Karabanov ,&nbsp;Eugeny Kryukov ,&nbsp;Gareth Morris ,&nbsp;Jeremy Good","doi":"10.1016/j.jmr.2025.107937","DOIUrl":"10.1016/j.jmr.2025.107937","url":null,"abstract":"<div><div>Reference deconvolution, a powerful mathematical tool for removing the effects of imperfections of the main magnetic field on NMR spectra, is revisited in the context of strong static and dynamic field perturbations. The theoretical basis and experimental evidence for the high efficiency of reference deconvolution for strong magnetic field distortions in basic liquid-state one- and two-dimensional NMR are given.</div><div>In particular, in 2D NMR, we utilise our observation that a strong static inhomogeneity of the main magnetic field suppresses anti-echo coherence transfer contributions, enabling reference deconvolution to be applied to the remaining echo contributions, in each indirect increment separately, in a manner similar to 1D NMR. We show that, in both 1D and 2D NMR, reference deconvolution enables one to remove the vibrational artefacts of cold head operation in cryogen-free magnets.</div><div>This extends the applicability of reference deconvolution in multi-dimensional NMR and advances cryogen-free technology in liquid-state NMR.</div></div>","PeriodicalId":16267,"journal":{"name":"Journal of magnetic resonance","volume":"379 ","pages":"Article 107937"},"PeriodicalIF":1.9,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144723392","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
Diamond rotors for high magic angle spinning frequencies 高魔角旋转频率的金刚石转子
IF 2 3区 化学
Journal of magnetic resonance Pub Date : 2025-10-01 Epub Date: 2025-05-26 DOI: 10.1016/j.jmr.2025.107909
Lauren Schaffer , David Preiss , Ravi Shankar Palani , Nicholas Wiesner , Jiaming Liu , Samuel Strymish , Salima Bahri , Sara Linse , Neil Gershenfeld , Robert G. Griffin
{"title":"Diamond rotors for high magic angle spinning frequencies","authors":"Lauren Schaffer ,&nbsp;David Preiss ,&nbsp;Ravi Shankar Palani ,&nbsp;Nicholas Wiesner ,&nbsp;Jiaming Liu ,&nbsp;Samuel Strymish ,&nbsp;Salima Bahri ,&nbsp;Sara Linse ,&nbsp;Neil Gershenfeld ,&nbsp;Robert G. Griffin","doi":"10.1016/j.jmr.2025.107909","DOIUrl":"10.1016/j.jmr.2025.107909","url":null,"abstract":"<div><div>Magic Angle Spinning (MAS) nuclear magnetic resonance (NMR) spectroscopy is limited in spectral resolution by the spinning frequency of rotors that hold the analyte. Traditional yttria-stabilized zirconia (YSZ) rotors have mechanical constraints that typically limit spinning frequencies of 0.7 mm rotors to ω<sub>r</sub>/2π ∼ 110 kHz. These frequencies are not sufficient to achieve resolution comparable to that of solution NMR, which theoretically requires ω<sub>r</sub>/2π &gt; 300 kHz. Building upon prior work that utilized rotary-assisted drilling, we present significant advances in diamond rotor fabrication using a high precision lathe and a centerless laser machining fixture that achieves improved concentricity of the rotor outer and inner diameters and spinning stability. The new crop of diamond rotors, which interface with the Bruker MAS 3 spinning system equivalently or better than commercial rotors, were spun using automatic 0.7 mm profiles. Furthermore, diamond rotors can be emptied and repacked, and we describe a set of 3D-printed centrifuge tools for efficient execution of this process. We evaluate chemical vapor deposition (CVD) versus high-pressure high-temperature (HPHT) diamonds as rotor material and find HPHT preferable. Extended spin stability tests and multidimensional NMR spectra of Aβ<sub>1</sub><sub>–</sub><sub>40</sub> demonstrate the robustness and usability of these rotors. These advances pave the way for higher frequency spinning with helium gas in the future, enabling transformative improvements in MAS NMR for biological and material sciences.</div></div>","PeriodicalId":16267,"journal":{"name":"Journal of magnetic resonance","volume":"379 ","pages":"Article 107909"},"PeriodicalIF":2.0,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144570748","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
Design and characterization of a tunable open TE011 resonator for Q-band pulse EPR experiments 用于q波段脉冲EPR实验的可调谐开放式TE011谐振腔的设计与表征
IF 2 3区 化学
Journal of magnetic resonance Pub Date : 2025-09-01 Epub Date: 2025-06-08 DOI: 10.1016/j.jmr.2025.107921
Kyle Jorgensen, Alexey Silakov
{"title":"Design and characterization of a tunable open TE011 resonator for Q-band pulse EPR experiments","authors":"Kyle Jorgensen,&nbsp;Alexey Silakov","doi":"10.1016/j.jmr.2025.107921","DOIUrl":"10.1016/j.jmr.2025.107921","url":null,"abstract":"<div><div>Electron Paramagnetic Resonance (EPR) is an important technique for the investigation of the structure and function of metalloproteins and enzymes. The variety of questions in this line of research requires versatile instrumentation. In this work, we explored the utility of the open resonator concept for a general-use highly tunable TE<sub>011</sub> resonator design at Q-band frequencies (≈ 34 GHz). Using proof-of-concept calculations, we establish a viable range of critical parameters compatible with the desired instrument specifications. We then present the resonator design, targeting ease of execution and handling. Experimental characterization of the built resonator shows high tunability. Specifically, we show that the resonator can be critically coupled and overcoupled with a three-fold change in the bandwidth using a matching short. We also show that the resonator can be incorporated with frequency tuning by means of movable axial plungers, allowing it to work with a wide range of samples using relatively narrow-bandwidth microwave instrumentation. Furthermore, because of its high tunability, the resonator is very tolerant of manufacturing imperfections, which makes it affordable and easy to execute with minimal tooling. We also discuss the long-term use of the resonator in our research, highlighting its versatility.</div></div>","PeriodicalId":16267,"journal":{"name":"Journal of magnetic resonance","volume":"378 ","pages":"Article 107921"},"PeriodicalIF":2.0,"publicationDate":"2025-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144270832","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
Probe design for high sensitivity proton-detected solid-state NMR 高灵敏度质子探测固态核磁共振探针设计
IF 2 3区 化学
Journal of magnetic resonance Pub Date : 2025-09-01 Epub Date: 2025-06-09 DOI: 10.1016/j.jmr.2025.107919
Collin G. Borcik , Lauren E. Price , John P. Heinrich , John A. Stringer , Chad M. Rienstra
{"title":"Probe design for high sensitivity proton-detected solid-state NMR","authors":"Collin G. Borcik ,&nbsp;Lauren E. Price ,&nbsp;John P. Heinrich ,&nbsp;John A. Stringer ,&nbsp;Chad M. Rienstra","doi":"10.1016/j.jmr.2025.107919","DOIUrl":"10.1016/j.jmr.2025.107919","url":null,"abstract":"<div><div>Proton (<sup>1</sup>H) detection methodologies in solid-state NMR (SSNMR) have revolutionized the field allowing for probing of new frontiers in determining the structure and dynamics within biological systems and materials. While approaches that maximally leverage the high gyromagnetic ratio of <sup>1</sup>H detection have enhanced sensitivity and resolution of SSNMR experiments, the radiofrequency (rf) circuit of magic-angle spinning (MAS) probes is not well optimized for <sup>1</sup>H detection, limiting the overall signal-to-noise ratio (SNR). Rather, SSNMR probes have historically been optimized for lower gamma nuclei such as <sup>13</sup>C and below. Here we present a design with an inner coil for proton (<sup>1</sup>H) to maximize <sup>1</sup>H sensitivity. Optimizing the <sup>1</sup>H channel resulted in a 1.33–2-fold increase in SNR with <sup>1</sup>H detection in a one-dimensional experiment. An outer coil is tuned to the <sup>13</sup>C and <sup>15</sup>N frequencies, with excellent B<sub>1</sub> homogeneity on all three channels. Using this design, we find that the sensitivity scales better than the theoretical expectations from 600 MHz to 750 MHz, due to a combination of the improved rf efficiency and B<sub>1</sub> homogeneity. We also demonstrate these improvements on a model protein system (GB1) with a 4D experiment collected in less than a day.</div></div>","PeriodicalId":16267,"journal":{"name":"Journal of magnetic resonance","volume":"378 ","pages":"Article 107919"},"PeriodicalIF":2.0,"publicationDate":"2025-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144297133","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
Circuit design for broadband decoupling in multi-coil multi-nuclear applications 多线圈多核应用中宽带去耦电路设计
IF 2 3区 化学
Journal of magnetic resonance Pub Date : 2025-09-01 Epub Date: 2025-06-18 DOI: 10.1016/j.jmr.2025.107924
Joseph Busher , Edith Touchet-Valle , Jacob Degitz , Mary P. McDougall
{"title":"Circuit design for broadband decoupling in multi-coil multi-nuclear applications","authors":"Joseph Busher ,&nbsp;Edith Touchet-Valle ,&nbsp;Jacob Degitz ,&nbsp;Mary P. McDougall","doi":"10.1016/j.jmr.2025.107924","DOIUrl":"10.1016/j.jmr.2025.107924","url":null,"abstract":"<div><div>The wealth of information available from multinuclear magnetic resonance imaging and spectroscopy is largely untapped in the clinical setting. This is due to a multitude of challenges in the pipeline ranging from acquisition strategies, hardware design, processing, and interpretation/analysis. As a small part of addressing these challenges, this work presents a straightforward approach for broadband decoupling between coils. This circuit was created with the implementation of a series PIN diode and was evaluated on the bench and experimentally for <sup>1</sup>H, <sup>31</sup>P and <sup>23</sup>Na at 3 T. Individual coils were single-tuned with this decoupling network and stacked to enable a switched triple-tuned coil. These coils were evaluated in various purposefully coupled configurations and compared to a narrowband trap active detuning network to demonstrate potential modularity of this design. Narrowband trapped coils showed drops in SNR when combined with other coils, presumably due to coupling between receiver elements tuned to different frequencies. This broadband decoupling behavior was shown to be independent of positioning through coils oriented to be nearly perfectly geometrically coupled and the addition of a three-element array of the same size. This configuration was validated on a post-mortem pig to verify the losses of the network did not prohibit its use for preclinical imaging and spectroscopy applications. Although losses were incurred as a result of the broadband decoupling network, it enabled a modular design that can be adapted to a given study without significant compromise of the signal integrity and could eliminate the need for certain custom coils for multi-nuclear studies.</div></div>","PeriodicalId":16267,"journal":{"name":"Journal of magnetic resonance","volume":"378 ","pages":"Article 107924"},"PeriodicalIF":2.0,"publicationDate":"2025-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144548630","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
Using solid-state MRI and a double-tuned RF coil to quantify bone matrix and mineral densities in rat bones 使用固态MRI和双调谐射频线圈量化大鼠骨骼中的骨基质和矿物质密度
IF 2 3区 化学
Journal of magnetic resonance Pub Date : 2025-09-01 Epub Date: 2025-06-20 DOI: 10.1016/j.jmr.2025.107925
Victor B. Kassey , Matthias Walle , Diana Yeritsyan , Daniel V. Kassey , Yaotang Wu , Brian D. Snyder , Edward K. Rodriguez , Jerome L. Ackerman , Ara Nazarian
{"title":"Using solid-state MRI and a double-tuned RF coil to quantify bone matrix and mineral densities in rat bones","authors":"Victor B. Kassey ,&nbsp;Matthias Walle ,&nbsp;Diana Yeritsyan ,&nbsp;Daniel V. Kassey ,&nbsp;Yaotang Wu ,&nbsp;Brian D. Snyder ,&nbsp;Edward K. Rodriguez ,&nbsp;Jerome L. Ackerman ,&nbsp;Ara Nazarian","doi":"10.1016/j.jmr.2025.107925","DOIUrl":"10.1016/j.jmr.2025.107925","url":null,"abstract":"<div><div>Quantitative information on the composition of bone, specifically the content of calcium phosphate mineral and organic matrix, is essential for accurate diagnosis of metabolic bone diseases such as osteoporosis, osteomalacia, and renal osteodystrophy, as well as for differentiating among these conditions. Conventional MRI fails to provide this information because these substances are solid and, therefore, yield no signal in conventional MRI scans, which typically employ spin or gradient echoes. In this report, we show how phosphorus and proton solid-state MRI yield the desired compositional information in bone specimens with ZTE and WASPI pulse sequences, respectively, coupled with the use of a two-port double-tuned solenoidal RF coil.</div><div>Electrical network simulations and construction details of the RF coil are detailed. Electrical performance was simulated using QUCS software to find the circuit component values that minimize reflected power and maximize interport isolation. Phantoms of known composition, as well as ex vivo femurs from normal, low bone density, and vitamin D-deficient rats, were included in the study. A simple correction for B<sub>1</sub> inhomogeneity was applied to achieve quantitative accuracy in the image intensity values.</div><div>Bone matrix and mineral densities derived from MRI strongly correlated (R<sup>2</sup> = 0.84) with chemical analysis, demonstrating the ability to measure compositional differences relevant to osteoporosis and osteomalacia.</div></div>","PeriodicalId":16267,"journal":{"name":"Journal of magnetic resonance","volume":"378 ","pages":"Article 107925"},"PeriodicalIF":2.0,"publicationDate":"2025-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144490632","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
Accurate image reconstruction from reduced data in pulsed electron paramagnetic resonance imaging 脉冲电子顺磁共振成像中简化数据的精确图像重建
IF 2 3区 化学
Journal of magnetic resonance Pub Date : 2025-09-01 Epub Date: 2025-06-23 DOI: 10.1016/j.jmr.2025.107920
Zheng Zhang , Boris Epel , Buxin Chen , Dan Xia , Emil Y. Sidky , Howard Halpern , Xiaochuan Pan
{"title":"Accurate image reconstruction from reduced data in pulsed electron paramagnetic resonance imaging","authors":"Zheng Zhang ,&nbsp;Boris Epel ,&nbsp;Buxin Chen ,&nbsp;Dan Xia ,&nbsp;Emil Y. Sidky ,&nbsp;Howard Halpern ,&nbsp;Xiaochuan Pan","doi":"10.1016/j.jmr.2025.107920","DOIUrl":"10.1016/j.jmr.2025.107920","url":null,"abstract":"<div><h3>Objective:</h3><div>We investigate and develop algorithms for reconstructing effective probe-density images, and then for obtaining oxygen-concentration images, from data of a subject collected at sparse views (SVs) or over a limited-angular range (LAR) for possibly achieving fast pulsed electron paramagnetic resonance imaging (EPRI). We refer to the effective probe-density image simply as the EPR image in the work.</div></div><div><h3>Methods:</h3><div>The reconstruction problem of EPR images from SV or LAR data in pulsed EPRI is formulated as an optimization program that includes a constraint either on the total variation (TV) or on the directional-TVs (DTVs) of the EPR image. Two algorithms, referred to as TV and DTV algorithms, are developed then for reconstruction of EPR images, respectively, from SV and LAR data through solving the respective optimization programs. Oxygen-concentration image is estimated subsequently from the EPR images reconstructed.</div></div><div><h3>Results:</h3><div>Using numerical studies with simulated data of a digital phantom and also with real data of a physical phantom and a mouse model, we demonstrate the potential of the TV and DTV algorithms that yield, respectively, from SV and LAR data, numerically accurate EPR and oxygen-concentration images.</div></div><div><h3>Conclusion:</h3><div>The TV and DTV algorithms developed can yield numerically accurate EPR and oxygen-concentration images, respectively, from SV and LAR data in pulsed EPRI.</div></div><div><h3>Significance:</h3><div>The work may yield insights into the design of scans with minimized scanning time, thus potentially enabling basic and preclinical <em>in vivo</em> studies with fast pulsed EPRI.</div></div>","PeriodicalId":16267,"journal":{"name":"Journal of magnetic resonance","volume":"378 ","pages":"Article 107920"},"PeriodicalIF":2.0,"publicationDate":"2025-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144548629","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
Towards complete suppression of diagonal peaks in solid-state MAS NMR homonuclear chemical shift correlation spectra 固态MAS核磁共振同核化学位移相关谱对角峰的完全抑制
IF 2 3区 化学
Journal of magnetic resonance Pub Date : 2025-09-01 Epub Date: 2025-06-25 DOI: 10.1016/j.jmr.2025.107926
Shengyu Zhang , Yuchen Li , Yansheng Ye , Fang Tian , Xinhua Peng , Riqiang Fu
{"title":"Towards complete suppression of diagonal peaks in solid-state MAS NMR homonuclear chemical shift correlation spectra","authors":"Shengyu Zhang ,&nbsp;Yuchen Li ,&nbsp;Yansheng Ye ,&nbsp;Fang Tian ,&nbsp;Xinhua Peng ,&nbsp;Riqiang Fu","doi":"10.1016/j.jmr.2025.107926","DOIUrl":"10.1016/j.jmr.2025.107926","url":null,"abstract":"<div><div>The feasibility of applying the spin-echo based diagonal peak suppression method in solid-state MAS NMR homonuclear chemical shift correlation experiments is demonstrated. A complete phase cycling is designed to generate sine- and cosine-modulations of the chemical shift difference between the spin-diffused signals, enabling the quadrature detection in the indirect dimension. Meanwhile, all signals not involved in polarization transfer are refocused at the center of the indirect dimension. A data processing algorithm is developed to extract and suppress these spin-echo refocused signals without affecting nearby spin-diffused cross peaks. The processed spectrum is then converted into a conventional two-dimensional homonuclear chemical shift correlation spectrum, free of diagonal peaks. The effectiveness of this method is illustrated using a uniformly <sup>13</sup>C-labeled Fmoc-leucine sample and a sample of human Atg8 homolog LC3B, directly conjugated to the amino headgroup of phosphatidylethanolamine (PE) lipids in liposomes.</div></div>","PeriodicalId":16267,"journal":{"name":"Journal of magnetic resonance","volume":"378 ","pages":"Article 107926"},"PeriodicalIF":2.0,"publicationDate":"2025-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144518107","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
Finite element modeling of Rb-129Xe spin-exchange optical pumping and optimized Rb source distribution 铷- 129xe自旋交换光泵浦的有限元建模及优化铷源分布
IF 2 3区 化学
Journal of magnetic resonance Pub Date : 2025-08-01 Epub Date: 2025-05-30 DOI: 10.1016/j.jmr.2025.107889
Jimmy E. Ball, Jim M. Wild, Graham Norquay
{"title":"Finite element modeling of Rb-129Xe spin-exchange optical pumping and optimized Rb source distribution","authors":"Jimmy E. Ball,&nbsp;Jim M. Wild,&nbsp;Graham Norquay","doi":"10.1016/j.jmr.2025.107889","DOIUrl":"10.1016/j.jmr.2025.107889","url":null,"abstract":"<div><div>Rubidium (Rb) vapor density (<span><math><mrow><mo>[</mo><mtext>Rb</mtext><mo>]</mo></mrow></math></span>) is a key parameter in xenon-129 polarization (<span><math><msub><mrow><mi>P</mi></mrow><mrow><mtext>Xe</mtext></mrow></msub></math></span>) build up in spin-exchange optical pumping. In practice, <span><math><mrow><mo>[</mo><mtext>Rb</mtext><mo>]</mo></mrow></math></span> within the cell often falls below saturation levels and is spatially heterogeneous leading to system underperformance. In this study, finite element modeling was performed to investigate the role of Rb source distribution in heterogeneous in-cell <span><math><mrow><mo>[</mo><mtext>Rb</mtext><mo>]</mo></mrow></math></span>, and to optimize a Rb presaturator to achieve homogeneous <span><math><mrow><mo>[</mo><mtext>Rb</mtext><mo>]</mo></mrow></math></span> and reduce the flow rate dependence of <span><math><mrow><mo>[</mo><mtext>Rb</mtext><mo>]</mo></mrow></math></span>. Lower than expected <span><math><msub><mrow><mi>P</mi></mrow><mrow><mtext>Xe</mtext></mrow></msub></math></span> in previous iterations of our polarizer can be attributed to sub-saturation <span><math><mrow><mo>[</mo><mtext>Rb</mtext><mo>]</mo></mrow></math></span> due to the small surface area of the Rb source in the main cell body and the absence of upstream Rb vapor presaturation, leading to lower than desired <span><math><msub><mrow><mi>P</mi></mrow><mrow><mtext>Xe</mtext></mrow></msub></math></span>. We found that increasing the surface area of the Rb source in the main cell body does not effectively reduce <span><math><mrow><mo>[</mo><mtext>Rb</mtext><mo>]</mo></mrow></math></span> heterogeneity. Instead, achieving a more uniform distribution of <span><math><mrow><mo>[</mo><mtext>Rb</mtext><mo>]</mo></mrow></math></span> necessitates the use of a sufficiently long presaturator at a given gas flow rate, increasing <span><math><msub><mrow><mi>P</mi></mrow><mrow><mtext>Xe</mtext></mrow></msub></math></span>. We also report discrepancy between modeled and experimentally measured laser absorption, highlighting limitations of the existing optical pumping model and suggesting directions for future model revisions and the investigation of currently unexplored areas.</div></div>","PeriodicalId":16267,"journal":{"name":"Journal of magnetic resonance","volume":"377 ","pages":"Article 107889"},"PeriodicalIF":2.0,"publicationDate":"2025-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144178273","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
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