SINGLET-DIFFUSION-NMR TO PROBE TRANSLATIONAL DYNAMICS IN POROUS MEDIA

单线态扩散核磁共振探测多孔介质中的平移动力学

• 批准号: EP/N033558/1
• 负责人: Giuseppe Pileio
• 金额: $ 12.87万
• 依托单位: University of Southampton
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2016
• 资助国家: 英国
• 起止时间: 2016 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=EP%2FN033558%2F1
• 关键词: SINGLET; DIFFUSION; NMR; PROBE; TRANSLATIONAL

Diffusion-NMR is a powerful technique with applications that span from material science to medicine. With the characteristic non-invasiveness and non-harmfulness of Nuclear Magnetic Resonance (NMR), the technique can infer information on molecular diffusion in various media. Diffusion-NMR has applications that range from analytic sciences where it can be used for example to sort out complex molecular mixtures according to different diffusion coefficients up to medicine where it is used to obtain contrast between biological tissues within which molecules have different diffusion properties.Porous media, which are ubiquitous in nature with examples including rocks, bones, wood etc. are perhaps the most suitable systems to be characterised through diffusion-NMR. And indeed scientific literature contains numerous examples of such investigations. However, because conventional NMR signals last typically for only up to a few seconds, diffusion-NMR studies have some limitations. The measurements of diffusion are done on a microscopic level by registering the changes in the intensity of an NMR signal as molecules diffuse in solution. The longer the diffusion time the farther the molecules diffuse, so that the the registered change in signal is more dramatic and the more accurate the measurement.Molecular diffusion is affected by the microscopic structure of the material a molecule diffuses within, therefore diffusion-NMR is a very sensitive tool to probe micro-structures, hence its great utility in porous media investigations. However its sensitivity to dimensions is directly linked to the timescale explored i.e. to the available diffusion time. Limitations to diffusion time due to the lifetime of conventional NMR signals therefore restrict the technique to geometries within 100 micrometers. Since many interesting porous structures have pore larger than 100 micrometers the technique cannot probe pore connectivity in those systems hence cannot provide a measure of tortuosity which is of instrumental importance in many areas including oil engineering and battery development. In the past 10 years I have been investigating the topic of long-lived spin states which are particular configurations of nuclear spin states displaying very long lifetimes that can reach in some cases even an hour length. This lifetime extension can be used in diffusion-NMR to prolong the diffusion time and obtain a better accuracy in diffusion measurement plus the possibility to access information on pore connectivity and hence measure tortuosity. This proposal deals with the development and assessment of methodology that exploit long-lived states to expand the accessible diffusion time in diffusion-NMR experiments thus giving access to measurement of tortuosity, macroscopic compartmentation and diffusion anisotropy in porous media. The main outcomes of this research are:1. molecular probes of diffusion that support long-lived states to give access to very long diffusion times2. NMR methodology to measure diffusion by encoding positional information on long-lived spin states 3. a simulation procedure for simulation of complex NMR experiments on porous systems4. measurements of tortuosity, anisotropic diffusion and macrostructures in porous media The proposed methodology is expected to benefit laboratories and industries with interests in characterising porous material and/or developing new materials (an increase in the tortuosity of lithium batteries' electrodes during electrochemical cycling is thought to be partially responsible for the observed reduction of performances, for example). Diffusion anisotropy is of particular interest in MRI where it is exploited in diffusion-tensor-imaging, a technique that uses diffusion anisotropy to map the direction of fibres in the body: methods and procedures developed in this project have the potential to impact this area too.

扩散核磁共振是一种功能强大的技术，其应用范围从材料科学到医学。利用核磁共振（NMR）的非侵入性和无害性，该技术可以推断各种介质中分子扩散的信息。扩散-NMR的应用范围从分析科学（例如，可用于根据不同的扩散系数分选复杂的分子混合物）到医学（用于获得分子具有不同扩散性质的生物组织之间的对比度）。多孔介质，其在自然界中普遍存在，例如岩石，骨骼，木材等可能是通过扩散-NMR表征的最合适的体系。事实上，科学文献中包含了许多这样的调查的例子。然而，由于常规NMR信号通常仅持续几秒钟，因此扩散NMR研究具有一些限制。通过记录分子在溶液中扩散时NMR信号强度的变化，在微观水平上进行扩散测量。扩散时间越长，分子扩散的距离越远，因此记录的信号变化就越剧烈，测量也就越准确。分子扩散受分子扩散所处材料的微观结构影响，因此扩散核磁共振是探测微观结构的一种非常灵敏的工具，因此在多孔介质研究中有很大的用途。然而，它对尺寸的敏感性直接与探索的时间尺度有关，即与可用的扩散时间有关。由于常规NMR信号的寿命对扩散时间的限制，因此将该技术限制在100微米内的几何形状。由于许多有趣的多孔结构具有大于100微米的孔，因此该技术不能探测这些系统中的孔连通性，因此不能提供在包括石油工程和电池开发在内的许多领域中具有重要意义的弯曲度的测量。在过去的10年里，我一直在研究长寿命自旋态的主题，这些自旋态是核自旋态的特殊配置，显示出非常长的寿命，在某些情况下甚至可以达到一个小时的长度。这种寿命延长可用于扩散NMR以延长扩散时间并获得更好的扩散测量准确度，以及访问孔连通性信息并因此测量弯曲度的可能性。该建议涉及开发和评估的方法，利用长寿命的状态，以扩大可访问的扩散时间在扩散-NMR实验，从而获得多孔介质中的曲折度，宏观划分和扩散各向异性的测量。本研究的主要成果有：1.扩散的分子探针，支持长寿命状态，以获得非常长的扩散时间2。NMR方法通过编码长寿命自旋态的位置信息来测量扩散3.一个模拟程序，用于模拟多孔系统上的复杂NMR实验4.多孔介质中弯曲度、各向异性扩散和宏观结构的测量所提出的方法预期将有益于对表征多孔材料和/或开发新材料感兴趣的实验室和工业（例如，在电化学循环期间锂电池电极弯曲度的增加被认为是所观察到的性能降低的部分原因）。扩散各向异性在MRI中特别令人感兴趣，它被用于扩散张量成像，这是一种使用扩散各向异性来绘制体内纤维方向的技术：该项目中开发的方法和程序也有可能影响这一领域。

项目成果

A dual-core NMR system for field-cycling singlet assisted diffusion NMR.

• DOI: 10.3389/fchem.2023.1229586
• 发表时间: 2023
• 期刊: Frontiers in chemistry
• 影响因子: 5.5

Long-lived Nuclear Spin Order - Theory and Applications

长寿命核自旋有序 - 理论与应用

• DOI: 10.1039/9781788019972-00302
• 发表时间: 2020
• 作者: Torres A

Correlative Visualization of Root Mucilage Degradation Using X-ray CT and MRI

使用 X 射线 CT 和 MRI 根部粘液降解的相关可视化

• DOI: 10.3389/fenvs.2018.00032
• 发表时间: 2018
• 期刊: Frontiers in Environmental Science
• 影响因子: 4.6
• 作者: Van Veelen A

A pulse sequence for singlet to heteronuclear magnetization transfer: S2hM.

用于单线态到异核磁化转移的脉冲序列：S2hM。

• DOI: 10.1016/j.jmr.2017.03.002
• 发表时间: 2017
• 期刊: 1997)
• 作者: Stevanato G

Singlet-assisted diffusion-NMR (SAD-NMR): extending the scope of diffusion tensor imaging via singlet NMR.

• DOI: 10.3389/fchem.2023.1224336
• 发表时间: 2023
• 期刊: Frontiers in chemistry
• 影响因子: 5.5