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A Multidisciplinary Research Platform for Nuclear Spins far from Equilibrium

远离平衡核自旋的多学科研究平台

基本信息

批准号：
EP/P009980/1
负责人：
Malcolm Levitt
金额：
$ 189.15万
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：
2017
资助国家：
英国
起止时间：
2017 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=EP%2FP009980%2F1
关键词：
Multidisciplinary Research Platform Nuclear Spins

项目摘要

Nuclear Magnetic Resonance (NMR) is a technique which uses the fact that the nuclei of many atoms act as tiny radiotransmitters, emitting radio signals at precisely-defined frequencies, which can be detected by a carefully-tuned detector. In an NMR experiment, the nuclei are first magnetised by placing a sample in a strong magnetic field for some time. A sequence of radiofrequency pulses is then applied to the sample, which subsequently emits radiowaves which are detected in the radio receiver. The pattern of emitted waves provides information on the chemical composition and spatial distribution of the sample.Magnetic nuclei may be viewed as small bar magnets, which may point in any direction in space. In normal circumstances the directions in which the nuclear magnets point are almost uniformly distributed, meaning that all directions are almost equally likely. As a result the net nuclear magnetism almost completely cancels out. However, when a strong magnetic field is applied, there is a very small change in this distribution, so that slightly more nuclei point along the applied field, than opposite to it. A very small net magnetism is developed along the applied field, and this is used to generate NMR and MRI signals. It is possible to generate materials with strongly perturbed nuclear spin distributions. There are two different types of non-equilibrium nuclear spin states. In the first type, the nuclei are strongly lined up in one direction, to a degree which is much greater than that which is available without intervention. Such materials are said to be hyperpolarized. Materials in hyperpolarized states can generate NMR signals which are 100000 stronger than normal. This phenomenon has already been used in clinical trials for the detection of cancer in human patients. In the second type of non-equilibrium spin state, neighbouring nuclei in the same molecule are strongly aligned with other, as opposed to being aligned along an external direction. In sufficiently symmetrical molecules, this leads to the phenomenon of spin isomerism, in which compounds with different nuclear spin configurations behave as separate physical substances, which can be stable for a long time. The seminal case is hydrogen gas (H2) where the spin isomers are called ortho and parahydrogen. These spin isomers were predicted to exist by Heisenberg (for which he was awarded a Nobel prize) and their existence is one of the triumphs of quantum mechanics. Recently our group showed that ordinary water may also exhibit ortho and para spin isomers, providing the water molecules are trapped inside carbon cages (fullerenes) so that they are free to rotate at low temperature. We also showed that the type of water spin isomer has an influence on the electrical properties of the material. In this Platform Grant we will further develop the sciences of hyperpolarization and spin isomerism and explore how they relate to each other. In some circumstances, spin isomerism may lead to hyperpolarization, and vice versa. By conducting this research we will learn a great deal about the behaviour of magnetic nuclei in symmetrical molecules, and develop new methods for enhancing NMR signals by enormous factors, which will have an impact on a wide range of sciences, including clinical medicine and the detection and characterisation of cancer. The new science of materials in nuclear spin states which are far from equilibrium also offers commercial opportunities in the form of novel MRI (magnetic resonance imaging) technology, and hyperpolarized imaging agents. During the project we will give our research team the opportunity to work flexibly and interactively across several interlocking disciplines. An innovation fund with an internal bidding process will be instituted to allow the participating researchers to explore their own ideas and to visit other laboratories.

核磁共振（NMR）是一种利用许多原子的原子核作为微小无线电发射器的事实的技术，它以精确定义的频率发射无线电信号，这些信号可以被精心调谐的探测器探测到。在核磁共振实验中，首先将样品置于强磁场中一段时间，使原子核磁化。然后将一系列射频脉冲施加到样品上，样品随后发出在无线电接收器中检测到的无线电波。发射波的模式提供了样品的化学成分和空间分布的信息。磁性原子核可以看作是小条形磁铁，可以指向空间中的任何方向。在正常情况下，核磁铁指向的方向几乎是均匀分布的，这意味着所有方向的可能性几乎是相等的。结果净核磁几乎完全抵消了。然而，当施加一个强磁场时，这种分布有一个非常小的变化，所以更多的原子核指向磁场方向，而不是相反方向。一个非常小的净磁场沿着应用领域发展，这是用来产生核磁共振和核磁共振信号。产生具有强扰动核自旋分布的材料是可能的。有两种不同类型的非平衡核自旋态。在第一种类型中，原子核在一个方向上强烈排列，其程度远远大于没有干预的程度。这种材料被称为超极化。处于超极化状态的材料可以产生比正常状态强100000倍的核磁共振信号。这种现象已经被用于临床试验，用于检测人类患者的癌症。在第二种非平衡自旋态中，同一分子中相邻的原子核强烈地排列在一起，而不是沿外部方向排列。在足够对称的分子中，这会导致自旋异构现象，在这种现象中，具有不同核自旋构型的化合物表现为独立的物理物质，可以长时间稳定。最典型的例子是氢气（H2），其自旋异构体被称为邻氢和对氢。这些自旋异构体的存在是由海森堡预言的（他因此获得了诺贝尔奖），它们的存在是量子力学的胜利之一。最近，我们的研究小组发现，如果水分子被困在碳笼（富勒烯）中，在低温下可以自由旋转，那么普通的水也可能表现出邻位和对位自旋异构体。我们还证明了水自旋异构体的类型对材料的电学性能有影响。在这个平台资助下，我们将进一步发展超极化和自旋同分异构科学，并探索它们之间的关系。在某些情况下，自旋同分异构体可能导致超极化，反之亦然。通过进行这项研究，我们将了解对称分子中磁性核的大量行为，并开发出通过巨大因素增强核磁共振信号的新方法，这将对广泛的科学领域产生影响，包括临床医学和癌症的检测和表征。远离平衡状态的核自旋态材料的新科学也以新的MRI（磁共振成像）技术和超极化显像剂的形式提供了商业机会。在项目期间，我们将为我们的研究团队提供在多个相互关联的学科中灵活互动的工作机会。将设立一个内部招标的创新基金，让参与的研究人员探索自己的想法，并参观其他实验室。