Journal of Magnetic Resonance Open最新文献_第3页

Paramagnetic relaxation: Direct and Raman relaxation of spin S=12 顺磁弛豫：自旋S=12的直接和拉曼弛豫

IF 2.624

Journal of Magnetic Resonance Open

Pub Date : 2025-06-01 Epub Date: 2025-03-12 DOI: 10.1016/j.jmro.2025.100193

W.Th. Wenckebach

Paramagnetic relaxation in solids is a vast subject, about as vast as the range of manifestations of electron spin in matter. It is a complex subject as well: it is the interface between paramagnetic centres – be it transition metal ions, radicals or defects – and quantized vibrations: phonons. So it requires an understanding of both these phonons and those paramagnetic centres. Moreover, contrary to the case of integer spin, for half-integer spin the coupling between electron spins and phonons is indirect. Two interactions are needed, the spin–orbit interaction between the spin and the orbits of the paramagnetic centre and the orbit–phonon interaction between the latter and the phonons.

The present article is an effort to navigate the theory of this extensive subject for spin

S = \frac{1}{2}

and aims to derive the main properties of the two most important mechanisms: direct and red Raman relaxation. It tries to do so from first principles, that is, it includes a generalized, but fundamental description of the vibrational states, the orbital and spin states on the one hand, and the orbit–phonon and spin–orbit interaction on the other. Based on these descriptions it derives the transition matrix elements responsible for paramagnetic relaxation, following the original approach of Van Vleck for paramagnetic centres with spin

S = \frac{1}{2}

, a relatively weak spin–orbit interaction and embedded in an insulating, diamagnetic solid. Subsequently phonon statistics are included to derive the paramagnetic relaxation rates. No effort is done to review the vast body of experimental work on the subject.

固体中的顺磁弛豫是一个庞大的课题，其范围与物质中电子自旋的表现形式一样庞大。它也是一个复杂的课题：它是顺磁性中心（无论是过渡金属离子、自由基还是缺陷）与量化振动（声子）之间的界面。因此，需要同时了解这些声子和顺磁中心。此外，与整数自旋的情况相反，对于半整数自旋，电子自旋与声子之间的耦合是间接的。本文旨在为自旋 S=12 的这一广泛课题的理论导航，并旨在推导出两种最重要机制的主要特性：直接拉曼弛豫和红色拉曼弛豫。文章试图从第一原理出发，即包括对振动状态、轨道和自旋状态以及轨道-声子和自旋-轨道相互作用的概括性但基本的描述。在这些描述的基础上，它按照范-弗莱克（Van Vleck）针对自旋 S=12 的顺磁中心、相对较弱的自旋轨道相互作用和嵌入绝缘二磁固体的原始方法，推导出了顺磁弛豫的过渡矩阵元素。随后加入声子统计，得出顺磁弛豫率。没有对有关这一主题的大量实验工作进行回顾。

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引用次数: 0

Introduction to average Hamiltonian theory. II. Advanced examples 平均哈密顿理论导论。2。先进的例子

IF 2.624

Journal of Magnetic Resonance Open

Pub Date : 2025-06-01 Epub Date: 2025-02-16 DOI: 10.1016/j.jmro.2025.100191

Andreas Brinkmann

Where the first part of our tutorial Introduction to average Hamiltonian theory (Brinkmann, 2016) introduced in detail the basic concepts and demonstrated the application to two composite radio-frequency (rf) pulses in nuclear magnetic resonance (NMR) spectroscopy, this second part will present in a comprehensive but educational manner two, more advanced examples for the application of average Hamiltonian theory in solid-state NMR spectroscopy, both to analyse and design rf pulse sequences: (i) The Rotational-Echo Double Resonance (REDOR) sequence, which recouples the heteronuclear dipolar coupling during sample rotation around an axis at the magic-angle of

54.7 4^{\circ}

with respect to the external static magnetic field. We will gradually increase the complexity of applying average Hamiltonian theory by first considering ideal, infinitesimally short rf pulses. Next, we will examine finite pulses with an rf phase of zero, and finally, we will explore finite pulses with arbitrary rf phases. In the latter case, if a first order average Hamiltonian proportional to heteronuclear longitudinal two-spin order (

2 I_{z} S_{z}

) is desired, solutions for the choice of rf phases include the XY and MLEV type schemes. (ii) The Lee–Goldburg homonuclear dipolar decoupling sequence under static samples conditions and its improved successors, Flip-Flop Lee–Goldburg (FFLG) and Frequency-Switched Lee–Goldburg (FSLG).

我们的教程《平均哈密顿理论介绍》（Brinkmann, 2016）的第一部分详细介绍了基本概念，并演示了在核磁共振（NMR）光谱中的两个复合射频（rf）脉冲的应用，第二部分将以全面但具有教育意义的方式呈现两个更高级的例子，用于平均哈密顿理论在固态核磁共振光谱中的应用，包括分析和设计rf脉冲序列。(i)旋转回声双共振（REDOR）序列，在样品相对于外部静态磁场以54.74°的魔角绕轴旋转时，将异核偶极耦合重新耦合起来。我们将通过首先考虑理想的、无限短的射频脉冲来逐渐增加应用平均哈密顿理论的复杂性。接下来，我们将研究射频相位为零的有限脉冲，最后，我们将探索具有任意射频相位的有限脉冲。在后一种情况下，如果期望与异核纵向双自旋阶（2IzSz）成比例的一阶平均哈密顿量，则射频相位选择的解包括XY和MLEV型格式。（ii）静态样本条件下的Lee-Goldburg同核偶极解耦序列及其改进后的触发器Lee-Goldburg （FFLG）和频率开关Lee-Goldburg （FSLG）。

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引用次数: 0

Probing cation dynamics and phase transition in hybrid organic-inorganic perovskites by 13C solid-state NMR spectroscopy at very high resolution 高分辨率13C固体核磁共振光谱探测有机-无机杂化钙钛矿的阳离子动力学和相变

IF 2.624

Journal of Magnetic Resonance Open

Pub Date : 2025-06-01 Epub Date: 2025-03-28 DOI: 10.1016/j.jmro.2025.100197

Yue Dou , Qing Wang , Hengxing Ji , Haiming Liu

The spatial dynamics of cations have a significant impact on the photodynamic behavior of excited states in high-performance hybrid organic-inorganic perovskites. Multinuclear (¹H, ²H, and ¹⁴N) solid-state NMR (SSNMR) spectroscopy has traditionally been utilized to study the motion of methylammonium (MA) cations in methylammonium lead (II) halides MAPbX₃ (X = I, Br, Cl). NMR methods based on spin-lattice relaxation or quadrupolar line shape analysis over a limited temperature range demonstrate rapid MA reorientation, but the cation dynamics in a wider temperature range covering phase transition of all major crystallographic phases is lacking. Due to its low sensitivity, ¹³C NMR is rarely used to assess MA dynamics in these perovskites. Herein, we adopte variable-temperature (VT) ¹³C MAS NMR at very high resolution and dipolar-coupled transverse relaxation analysis as a new tool for dynamical characterization without isotopic enrichment, and systematically investigated MA dynamics in MAPbX₃ across phase transitions. This new approach enables retrieval of activation energy of MA reorientation and assessment of motion regimes. We propose a generalized “Camel model” that describes the common trend of cation dynamics for MAPbX₃, suggesting possible complicated reorientation modes. Furthermore, we discover the evolution of multiple MA sites in orthorhombic MAPbCl₃, consistent with X-ray crystallography, demonstrating its unique advantage in resolving and characterizing multi-cation dynamics. The VT ¹³C SSNMR effectively probes organic ion motions and phase transitions in hybrid perovskites, helpful for further elucidating the structure-property relationship in photovoltaic conversion mechanisms.

阳离子的空间动力学对高性能有机-无机杂化钙钛矿中激发态的光动力学行为有重要影响。多核（1H， 2H和14N）固态核磁共振（SSNMR）光谱传统上被用于研究甲基铵铅（II）卤化物MAPbX3 （X = I, Br, Cl）中甲基铵（MA）阳离子的运动。基于自旋晶格弛豫或四极线形分析的核磁共振方法在有限的温度范围内显示出快速的MA重定向，但缺乏涵盖所有主要晶体相相变的更宽温度范围内的阳离子动力学。由于其低灵敏度，13C核磁共振很少用于评估这些钙钛矿中的MA动力学。本文采用超高分辨率的变温13C MAS NMR和偶极耦合横向弛豫分析作为不富集同位素的动力学表征新工具，系统地研究了MAPbX3在不同相变中的MA动力学。这种新方法可以检索MA重新定向的激活能和评估运动状态。我们提出了一个广义的“骆驼模型”，描述了MAPbX3阳离子动力学的共同趋势，提出了可能的复杂重定向模式。此外，我们发现了正交MAPbCl3中多个MA位点的演化，与x射线晶体学一致，证明了其在解析和表征多阳离子动力学方面的独特优势。VT 13C SSNMR有效地探测了杂化钙钛矿中有机离子的运动和相变，有助于进一步阐明光伏转换机制中的结构-性能关系。

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引用次数: 0

Determination of the surface relaxivity of soft sediment using particle size and shape 用颗粒大小和形状测定软沉积物的表面弛豫度

IF 2.624

Journal of Magnetic Resonance Open

Pub Date : 2025-06-01 Epub Date: 2025-04-02 DOI: 10.1016/j.jmro.2025.100198

Nick J. Hol , Ismail Myouri , Claire Chassagne , Leo Pel

This study presents a method to determine surface relaxivity in soft sediments by combining one-dimensional Nuclear Magnetic Resonance (NMR) imaging with particle size and shape estimates. In order to determine the surface relaxivity up to now often methods like Mercury Intrusion Porosimetry or Brunauer–Emmett–Teller (BET) are used which where drying steps are involved which can alter material properties during analysis, particularly in highly deformable materials, making these techniques unreliable for soft soils. By combining NMR relaxometry and estimates of particle sizes and shapes of a soft soil, this new approach provides accurate, non-invasive surface relaxivity measurements. This method is demonstrated on kaolinite, glass beads, and natural soils, showing that this method supports detailed assessment of pore size distributions in soft sediments, benefiting geotechnical and environmental research where soil stability is critical.

本研究提出了一种将一维核磁共振成像与颗粒大小和形状估计相结合的方法来确定软沉积物的表面弛豫度。到目前为止，为了确定表面松弛度，通常使用汞侵入孔隙法或布鲁诺尔-埃米特-泰勒（BET）等方法，这些方法涉及干燥步骤，在分析过程中会改变材料的特性，特别是在高度变形的材料中，使得这些技术对软土不可靠。通过结合核磁共振弛豫测量和软土颗粒大小和形状的估计，这种新方法提供了准确的，非侵入性的表面弛豫测量。该方法在高岭石、玻璃微珠和天然土壤中得到了验证，表明该方法支持对软质沉积物中孔隙大小分布的详细评估，有利于土壤稳定性至关重要的岩土工程和环境研究。

引用次数: 0

Chiral recognition of some D and L-amino acids by microcrystalline cellulose assisted diffusion-ordered NMR spectroscopy 微晶纤维素辅助扩散有序核磁共振光谱法手性识别某些D和l氨基酸

IF 2.624

Journal of Magnetic Resonance Open

Pub Date : 2025-03-01 Epub Date: 2025-02-01 DOI: 10.1016/j.jmro.2025.100189

Bowen Han , Jing He , Shaohua Huang

Chiral amino acids play an indispensable role in living organisms. Diffusion-ordered NMR spectroscopy is an effective NMR tool and a noninvasive analytical method for the analyses of mixture without the need for physical separation of the analytes. However, conventional diffusion-ordered NMR spectroscopy method usually fails to resolve the mixtures of chiral amino acids because of their same molecular masses, sizes, and shapes. Microcrystalline cellulose has been gradually gained more and more interest owing to its wide compatibility, surface area, excellent separation efficiency, non-toxicity, cost-effective, and mechanical stability in many fields. Herein we provide a fast, simple, specific and sensitive method to resolve some D and L-amino acids mixtures by using microcrystalline cellulose as a matrix. This work recognized some D and L- proteinogenic amino acid enantiomers with diffusion-ordered NMR for the first time.

手性氨基酸在生物体中起着不可缺少的作用。扩散有序核磁共振波谱法是一种有效的核磁共振分析工具，是一种无需对被分析物进行物理分离就能对混合物进行分析的无创分析方法。然而，由于手性氨基酸的分子质量、大小和形状相同，传统的扩散有序核磁共振波谱方法通常无法解析手性氨基酸的混合物。微晶纤维素因其相容性广、表面积大、分离效率高、无毒、经济、机械稳定性好等优点，在许多领域逐渐受到人们的关注。本文以微晶纤维素为基质，提供了一种快速、简单、特异、灵敏的方法来分离D和l氨基酸混合物。本工作首次用扩散有序核磁共振识别了一些D -和L-蛋白质原氨基酸对映体。

引用次数: 0

A hybrid setup for rodent hyperpolarized metabolic imaging using a clinical magnetic resonance scanner 一种用于临床磁共振扫描仪的啮齿类动物超极化代谢成像的混合装置

IF 2.624

Journal of Magnetic Resonance Open

Pub Date : 2025-03-01 Epub Date: 2025-01-28 DOI: 10.1016/j.jmro.2025.100190

Ditte Bentsen Christensen , Ingeborg Sæten Skre , Jan Henrik Ardenkjær-Larsen , Mor Mishkovsky , Mathilde H Lerche

Metabolic magnetic resonance spectroscopic imaging using hyperpolarized contrast agents offers a non-invasive approach to monitoring real-time in vivo energy metabolism. The technique involves hyperpolarizing a contrast agent in a polarizer, administering it to a living system, and then imaging its distribution and metabolites using a magnetic resonance scanner. Over the past two decades, the method has transitioned from in vitro studies to clinical research, with an increasing focus on clinical applications.

Here, we present a hybrid system that adapts a clinical magnetic resonance scanner for pre-clinical rodent experiments. The hybrid system includes (1) a customizable, 3D-printable animal cradle setup and (2) optimized imaging strategies, including coil configurations, metabolic contrast agent administration, and proton imaging acquisition. The system enables ¹³C dynamic imaging, which we illustrate with detection of hyperpolarized [1–¹³C]pyruvate and its metabolites in the mouse brain. We detail the experimental procedure, provide practical guidance, and showcase the capabilities of the system with example data from mouse brain imaging.

This hybrid setup bridges the gap between clinical and pre-clinical research, enabling iterative testing of equipment, imaging sequences, and hypotheses across phantoms, in vivo rodent models and clinical settings. By facilitating a smoother translation, both forward and reverse, between pre-clinical and clinical applications, this approach enhances the potential for advancing metabolic imaging research.

使用超极化造影剂的代谢磁共振光谱成像为实时监测体内能量代谢提供了一种非侵入性方法。该技术包括在偏光器中对造影剂进行超极化，将其施用于活体系统，然后使用磁共振扫描仪对其分布和代谢物进行成像。在过去的二十年中，该方法已经从体外研究过渡到临床研究，越来越关注临床应用。在这里，我们提出了一个混合系统，适应临床磁共振扫描仪的临床前啮齿动物实验。该混合系统包括(1)可定制的3d打印动物摇篮设置和(2)优化的成像策略，包括线圈配置、代谢造影剂管理和质子成像采集。该系统能够实现13C动态成像，我们通过检测小鼠大脑中的超极化[1-13C]丙酮酸及其代谢物来说明这一点。我们详细介绍了实验过程，提供了实用的指导，并通过小鼠脑成像的示例数据展示了该系统的功能。这种混合装置弥合了临床和临床前研究之间的差距，使设备、成像序列和假设能够在幻影、体内啮齿动物模型和临床环境中进行迭代测试。通过促进临床前和临床应用之间更顺畅的正向和反向转换，该方法增强了推进代谢成像研究的潜力。

{"title":"A hybrid setup for rodent hyperpolarized metabolic imaging using a clinical magnetic resonance scanner","authors":"Ditte Bentsen Christensen , Ingeborg Sæten Skre , Jan Henrik Ardenkjær-Larsen , Mor Mishkovsky , Mathilde H Lerche","doi":"10.1016/j.jmro.2025.100190","DOIUrl":"10.1016/j.jmro.2025.100190","url":null,"abstract":"<div><div>Metabolic magnetic resonance spectroscopic imaging using hyperpolarized contrast agents offers a non-invasive approach to monitoring real-time in vivo energy metabolism. The technique involves hyperpolarizing a contrast agent in a polarizer, administering it to a living system, and then imaging its distribution and metabolites using a magnetic resonance scanner. Over the past two decades, the method has transitioned from in vitro studies to clinical research, with an increasing focus on clinical applications.</div><div>Here, we present a hybrid system that adapts a clinical magnetic resonance scanner for pre-clinical rodent experiments. The hybrid system includes (1) a customizable, 3D-printable animal cradle setup and (2) optimized imaging strategies, including coil configurations, metabolic contrast agent administration, and proton imaging acquisition. The system enables <sup>13</sup>C dynamic imaging, which we illustrate with detection of hyperpolarized [1–<sup>13</sup>C]pyruvate and its metabolites in the mouse brain. We detail the experimental procedure, provide practical guidance, and showcase the capabilities of the system with example data from mouse brain imaging.</div><div>This hybrid setup bridges the gap between clinical and pre-clinical research, enabling iterative testing of equipment, imaging sequences, and hypotheses across phantoms, in vivo rodent models and clinical settings. By facilitating a smoother translation, both forward and reverse, between pre-clinical and clinical applications, this approach enhances the potential for advancing metabolic imaging research.</div></div>","PeriodicalId":365,"journal":{"name":"Journal of Magnetic Resonance Open","volume":"22 ","pages":"Article 100190"},"PeriodicalIF":2.624,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143353597","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}

引用次数: 0

Dynamic electron and nuclear spin polarization in solution using porphyrin and tris(2,4,6-trichlorophenyl)-methyl (TTM) radical derivatives 卟啉和三（2,4,6-三氯苯基）-甲基（TTM）自由基衍生物在溶液中的动态电子和核自旋极化

IF 2.624

Journal of Magnetic Resonance Open

Pub Date : 2025-03-01 Epub Date: 2024-12-09 DOI: 10.1016/j.jmro.2024.100181

Reiya Yabuki , Koki Nishimura , Yuta Sawada , Masaaki Fuki , Yasuhiro Kobori , Nobuhiro Yanai

Chemically induced dynamic electron polarization (CIDEP) generates radical electron spins with high polarization at room temperature by quenching the photo-excited state of chromophores, which is useful for microwave-free optical dynamic nuclear polarization (DNP) in solution. While nitroxyl (TEMPO) radicals are typically used for this purpose, we show that a tris(2,4,6-trichlorophenyl)-methyl (TTM) radical derivative shows greater electron spin polarization than TEMPO by CIDEP using porphyrin chromophores. This is attributed to the longer spin-lattice relaxation time of TTM radicals, with a contribution of efficient quenching of chromophore photo-excited state by energy transfer from the triplet state of porphyrins to the doublet state of the TTM radicals. The porphyrin-TTM pair shows a larger nuclear spin polarization under continuous laser excitation than the porphyrin-TEMPO pair because of the larger polarization and longer spin-lattice relaxation time of the TTM radical electron spins. This work demonstrates the first example of in-solution CIDEP and optically-driven DNP using TTM radicals, opening new opportunities in a wide range of biological and medical applications.

化学诱导动态电子极化（CIDEP）通过猝灭发色团的光激发态，在室温下产生具有高极化的自由基电子自旋，为溶液中无微波光学动态核极化（DNP）的研究提供了理论依据。虽然硝基（TEMPO）自由基通常用于此目的，但我们发现三（2,4,6-三氯苯基）-甲基（TTM）自由基衍生物在使用卟啉发色团的CIDEP中表现出比TEMPO更大的电子自旋极化。这是由于TTM自由基的自旋晶格弛豫时间较长，这是由于从卟啉的三重态到TTM自由基的双重态的能量转移有效地猝灭了发色团的光激发态。在连续激光激发下，卟啉-TTM对表现出比卟啉- tempo对更大的核自旋极化，这是由于TTM自由基电子自旋的极化更大，自旋晶格弛豫时间更长。这项工作展示了溶液内CIDEP和使用TTM自由基的光驱动DNP的第一个例子，为广泛的生物和医学应用开辟了新的机会。

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引用次数: 0

Unveiling the impact of second-order 1H-17O Quadrupolar-Dipolar interaction on solid-state NMR spectroscopy 揭示二级1H-17O四极-偶极相互作用对固体核磁共振波谱的影响

IF 2.624

Journal of Magnetic Resonance Open

Pub Date : 2025-03-01 Epub Date: 2024-12-10 DOI: 10.1016/j.jmro.2024.100182

Yi Ji , Kuizhi Chen , Aijing Hao , Guangjin Hou

Recent advances in the ¹⁷O-enrichment techiques and high-resolution nuclear magnetic resonance (NMR) methods have opened new opportunities to utilize ¹⁷O NMR to disentangle the zeolitic structure−property relationship that has not been well resolved through traditional ¹H, ²⁷Al, and ²⁹Si NMR spectroscopy. Compared with one-dimensional ¹⁷O magic angle spinning (MAS) NMR experiments, ¹H-¹⁷O correlation spectrocopy has become a crucial method for revealing the structures and dynamics of reactive hydroxyl species in zeolites with higher resolution and precision. However, the introduction of ¹⁷O can induce changes in ¹H MAS NMR signals due to the second-order ¹H-¹⁷O quadrupolar-dipolar (2nd-QD) cross interaction, which has recently been revealed by us on H-ZSM-5 (H-MFI) zeolites with 10-membered-ring (MR) channels. Herein, we performed various ¹H-¹⁷O correlation experiments (¹H{¹⁷O}-J-heteronuclear multiple quantum coherence (HMQC), ¹H{¹⁷O}-D-HMQC, and ¹H→¹⁷O-D-RINEPT) on two other types of ¹⁷O-enriched zeolites, i.e., H-Mordenite (H-MOR) with 8-/12-MR channels and H-ZSM-35 (H-FER) with 8-/10-MR channels. Notably, unusual ¹H-¹⁷O correlation signals with tilted patterns and magnetic-field-dependent shifts were observed on both samples and all tested correlation experiments at high fields up to 18.8 T. These observations were further comprehensively explained by theoretical analysis of the ¹H-¹⁷O quadrupolar-dipolar interaction, thus demonstrating that the ¹H-¹⁷O 2nd-QD interaction generally affects the ¹H and ¹H-¹⁷O correlation MAS NMR spectra of the dehydrated ¹⁷O-enriched zeolites, irrespective of the framework types. Beyond zeolites, the non-ignorable 2nd-QD interaction on NMR spectroscopy can complicate NMR identification of ¹⁷O-labeled hydroxyls in many other inorganic materials and biomolecules. The analysis methods proposed in this study are expected to effectively address these challenges and provide clearer insights into such systems.

17O富集技术和高分辨率核磁共振（NMR）方法的最新进展为利用17O NMR来解开传统1H、27Al和29Si核磁共振光谱无法很好解决的沸石结构-性质关系开辟了新的机会。与一维17O魔角旋转（MAS）核磁共振实验相比，1H-17O相关光谱以更高的分辨率和精度成为揭示沸石中活性羟基结构和动力学的重要方法。然而，17O的引入会引起1H MAS NMR信号的变化，这是由于二阶1H-17O四极-偶极（2 - qd）交叉相互作用，最近我们在具有10元环（MR）通道的H-ZSM-5 （H-MFI）沸石上发现的。在此，我们对另外两种富含17O的沸石，即具有8-/12-MR通道的h -丝光沸石（H-MOR）和具有8-/10-MR通道的H-ZSM-35 （H-FER）进行了各种1H-17O相关实验（1H{17O}- j -异核多重量子相干性（HMQC）、1H{17O}- d -HMQC和1H→17O- d - rinept）。值得注意的是，在两个样品和所有测试的相关实验中，在高达18.8 t的高场下，都观察到异常的倾斜模式和磁场依赖位移的1H- 17o相关信号。这些观察结果进一步通过1H- 17o四极-偶极相互作用的理论分析得到了全面的解释，从而表明1H- 17o第2 - qd相互作用通常影响脱水富17o沸石的1H和1H- 17o相关MAS NMR谱。不管框架类型如何。除沸石外，核磁共振波谱上不可忽视的第二量子点相互作用使许多其他无机材料和生物分子中17o标记羟基的核磁共振鉴定复杂化。本研究提出的分析方法有望有效解决这些挑战，并为此类系统提供更清晰的见解。

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引用次数: 0

Developing hyperpolarized metabolic contrast agents at high field dDNP for large animal research 大动物实验高场dDNP超极化代谢造影剂的研制

IF 2.624

Journal of Magnetic Resonance Open

Pub Date : 2025-03-01 Epub Date: 2024-12-27 DOI: 10.1016/j.jmro.2024.100184

Ditte B. Christensen , Ingeborg S. Skre , Jan Henrik Ardenkjær-Larsen, Magnus Karlsson, Mathilde H. Lerche

Dissolution Dynamic Nuclear Polarization (dDNP) polarizers have achieved high field strengths and large sample volumes. These advancements necessitate new formulations of hyperpolarized metabolic contrast agents (HMCAs) to enable large animal studies. While several metabolic substrates have been investigated at lower field dDNP and tested as HMCAs in rodents, ¹³C-labeled pyruvate remains the most studied HMCA and is currently the only one actively used in clinical trials due to its favorable biological and physical properties. Effective human and large animal dDNP formulations require high molar substrate concentrations, low DNP sample viscosity for efficient dissolution, and adequate dilution of the DNP sample to minimize signal decay and maximize HMCA concentration.

We present substrate formulations optimized for high-field polarization and large-volume dissolution. Specifically, we validate the upscaling of [1–¹³C]pyruvate under high-field conditions and demonstrate that [1–¹³C]2-keto-isocaproate and [1,4–¹³C₂]fumarate, which have been proven successful in rodent studies, can be formulated to yield high polarization at suitable concentrations and volumes for large animal metabolic MR imaging.

溶解动态核极化（dDNP）偏振器实现了高场强和大样本量。这些进步需要新的超极化代谢造影剂（HMCAs）配方来进行大型动物研究。虽然在低场dDNP下已经研究了几种代谢底物，并在啮齿动物中作为HMCA进行了测试，但13c标记的丙酮酸仍然是研究最多的HMCA，并且由于其良好的生物学和物理特性，目前是唯一一种积极用于临床试验的HMCA。有效的人类和大型动物dDNP配方需要高摩尔底物浓度，低DNP样品粘度以有效溶解，并充分稀释DNP样品以减少信号衰减和最大化HMCA浓度。我们提出了适合高场极化和大体积溶解的衬底配方。具体来说，我们验证了[1 - 13c]丙酮酸在高场条件下的放大，并证明[1 - 13c]2-酮-异己酸酯和[1,4 - 13c2]富马酸酯在啮齿动物研究中已被证明是成功的，可以在合适的浓度和体积下形成高极化，用于大型动物代谢MR成像。

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引用次数: 0

Hyperpolarized 129Xe for benchtop NMR: Inline instrumentation for automated yet flexible operation yielding high polarization 用于台式核磁共振的超极化129Xe：内联仪器，用于自动化但灵活的操作，产生高极化

IF 2.624

Journal of Magnetic Resonance Open

Pub Date : 2025-03-01 Epub Date: 2024-12-10 DOI: 10.1016/j.jmro.2024.100179

Wolfgang Kilian , Samira Gulich , Thomas Riemer , Lorenz Mitschang

The use of hyperpolarized media in combination with benchtop NMR spectrometers is currently extensively investigated to enable cost effective but highly sensitive applications. In this work, the instrumentation for the use of hyperpolarized ¹²⁹Xe gas on a commercial benchtop-NMR spectrometer in a fully controllable yet automated mode is presented. A continuous-flow ¹²⁹Xe polarizer is operated inline with the benchtop spectrometer. While the adjustment of the xenon gas partial pressure in the range of mbar to bar as well as the volume flow through the NMR sample is facilitated by the polarizer’s mass-flow controllers and two back-pressure regulators, respectively, the gas flow towards the NMR sample in situ in the benchtop magnet is time-controlled within the spectrometer’s RF pulse sequence programming. A calibration procedure for the gas flow control as well as thermally polarized xenon gas standards are introduced for quantification of the absolute ¹²⁹Xe polarization. In this way, the ¹²⁹Xe polarization achieved in the NMR measurement is determined in the 50% to 5% regime for very lean 1 mbar to high 500 mbar xenon partial pressure, respectively – in the optimum a more than 250,000-fold increase in comparison to thermal polarization. Such instrumentation may be implemented by combining any of the well-established continuous-flow ¹²⁹Xe polarizer with any of the commercial benchtop spectrometers, thus facilitating high-performance hyperpolarized ¹²⁹Xe benchtop NMR studies.

超极化介质与台式核磁共振光谱仪相结合的使用目前被广泛研究，以实现成本效益和高灵敏度的应用。在这项工作中，介绍了在完全可控的自动化模式下，在商用台式核磁共振光谱仪上使用超极化129Xe气体的仪器。一个连续流动的129Xe偏振器与台式光谱仪联机操作。虽然氙气分压在毫巴到巴范围内的调节以及通过核磁共振样品的体积流分别由偏振器的质量流控制器和两个背压调节器促进，但在台式磁铁中流向核磁共振样品的气体流是在光谱仪的射频脉冲序列编程中进行时间控制的。介绍了气体流量控制和热极化氙气体标准的校准程序，用于定量的绝对129Xe偏振。通过这种方式，在核磁共振测量中获得的129Xe极化分别在非常低的1mbar到500mbar的氙气分压下的50%到5%的范围内确定-在最佳情况下，与热极化相比增加了25万倍以上。这种仪器可以通过将任何成熟的连续流129Xe偏振器与任何商用台式光谱仪相结合来实现，从而促进高性能超极化129Xe台式核磁共振研究。

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引用次数: 0