Chemical shift plays an important role in molecular analysis. However, chemical shifts are influenced by temperature, solvent concentration, pressure, and so forth. Therefore, measuring chemical shift perturbations caused by these factors is helpful to molecular studies. A new form of 2-D spectroscopy (projection spectroscopy) has been introduced whose indirect dimension is derived by implementing the Radon transform on a series of conventional 1-D proton spectra and indicates such perturbations. However, signal overlap may exist in the conventional 1-D spectra and hence in the resulting projection spectra, hampering clear multiplet analysis and accurate extraction of perturbations. Here, the pure shift decoupling technique is employed to obtain clearer projection spectrum with higher spectral resolution. The combination of pure shift technique and the Radon transform is helpful to accurately extract chemical shift perturbations. It is believed that this application will open up a vast prospect for molecular analysis.

Enzymatic hydrolysis of phospholipids is an important biological event in organisms that is also widely applied in the food industry. In situ nuclear magnetic resonance (NMR) is a powerful non-invasive technique for studying the mechanism of enzymatic reactions. However, their application in phospholipid hydrolysis is limited. In this study, we demonstrated that in a phospholipase A1 (PLA1)-catalysed 1,2-diacyl-sn-glycero-3-phosphocholine (POPC) hydrolysis system in an aqueous emulsion, the accumulation of POPC hydrolysates caused severe heterogeneity, which significantly reduced the 1H NMR spectral intensity and resolution. To overcome the sample heterogeneity, we used the intermolecular dipolar-interaction enhanced all lines-II (IDEAL-II) sequence to obtain one-dimensional (1D) high-resolution 1H intermolecular double quantum coherence (iDQCs) NMR spectra through two-dimensional (2D) acquisition. These spectra enabled us to assign and trace the characteristic peaks of POPC and its hydrolysates in real time. In particular, we performed quantitative estimation of the reaction kinetics based on the g2 and g3 protons and provided direct evidence of the enzymatic hydrolysis process. This study not only fills the gap in 1D 1H spectrum data of phospholipids and their mixtures with hydrolysates, but also provides an effective method for a comprehensive and rapid analysis of fatty acids and even more complex heterogeneous systems. © 2023 The Authors

＜正＞核磁共振（NMR）波谱技术为分子结构解析和动力学分析提供一种重要的非侵入性检查手段。在核磁共振检测应用中,谱图分辨率是决定谱图结果可用性的重要因素[1]。由于有限化学位移范围和J偶合裂分效应,常规一维氢谱（~1H NMR）技术在复杂样品检测中往往受到谱峰拥挤甚至重叠的干扰,而降低谱图分辨。此外,实际检测中往往还存在一些不利的实验条件,如磁体环境或样品条件引起的

＜正＞核磁共振（NMR）波谱能够获取化学位移,J偶合和各峰面积之比等等的分子水平信息,在无损检测分子结构和测定样品成分方面有着重要应用。此外,NMR波谱还能用于获取分子动力学的重要信息。横向自旋-自旋（T2）弛豫时间的测量是核磁共振的一个重要分支,它能为各种应用提供重要的信息,如蛋白质骨架动力学研究,大分子内部动力学研究以及磁共振成像（MRI）中疾病诊断的对比机制研究。Carr-Purcell Meiboom-Gill（CPMG）方法为

背景:磁共振波谱（Magnetic Resonance Spectroscopy,MRS）因其非侵入性在医学脑代谢领域大放异彩。颞叶癫痫发作（Temporal Lobe Epileptic Seizures,TLES）给患者及其家属带来沉重的伤害,与此同时还存在着一种发作病症表现非常像癫痫发作的器质性非癫痫性发作（Organic Non-epileptic Seizures,ONES）。本文利用MRS来探究TLES患者和ONES患者之间的脑代谢物的差异,并揭示不同的场强的磁共振仪对区分癫痫患者与健康个体的敏感性的影响。方法:利用病例对照的研究思路,在临床1.5T磁共振系统上对皆处在发作后期的23例TLES患者和9例ONES患者进行了 MRS数据采集,同时利用15名健康志愿者的1.5T数据作为对照。以年龄作为协变量使用Mann-Whitney U检验,对大脑代谢物的比值进行了统计分析。此外在临床3T磁共振系统上对处在发作后期的29例TLES患者进行了 MRS数据采集,同时利用6名健康志愿者的3T数据作为对照,并和23例TLES患者和5名健康志愿者的1.5T的MRS数据进行交叉对比。结果:TLES组与ONES组相比较时,TLES组左颞极的N-乙酰天门冬氨酸/肌酸（N-acetyl-aspartate/Creatine,NAA/Cr）比值明显低于 ONES 组（TLES 组为1.422±0.037,ONES 组为 1.640±0.061,P=0.012）;TLES 组右颞极的 NAA/Cr 比值明显低于 ONES 组（TLES 组为 1.470±0.052,ONES 组为 1.687±0.084,P=0.023）。场强为1.5T和3T的磁共振仪并不会因为场强差异而导致MRS数据产生差异（P＜0.05）。此外TLES组与健康对照组在脑代谢物上的差异体现在NAA/Cr、N-乙酰天门冬氨酸/胆碱（N-acetyl-aspartate/Choline,NAA/Cho）和N-乙酰天门冬氨酸/（胆碱+肌酸）（N-acetyl-aspartate/（Choline+Creatine）,NAA/（Cho+Cr））。结论:本文发现处在发作后期的TLES组与ONES组在脑代谢物上的显著性差异体现在NAA/Cr,NAA/Cr有可能作为一个区分诊断TLES和ONES的推荐参考值,这一点在我们已知的参考文献中未找到这一点。此外,对不同场强下MRS数据的对比表明1.5T系统与3T系统在利用MRS检测脑代谢物含量以诊断癫痫患者时,这二者无明显差异,因此可推荐1.5T系统作为诊断癫痫首选设备以节省医疗成本。

＜正＞核磁共振（NMR）波谱能够获取化学位移,J偶合和各峰面积之比等等的分子水平信息,在无损检测分子结构和测定样品成分方面有着重要应用。此外,NMR波谱还能用于获取分子动力学的重要信息。横向自旋-自旋（T2）弛豫时间的测量是核磁共振的一个重要分支,它能为各种应用提供重要的信息,如蛋白质骨架动力学研究,大分子内部动力学研究以及磁共振成像（MRI）中疾病诊断的对比机制研究。Carr-Purcell Meiboom-Gill（CPMG）方法为

＜正＞作为一种稳健的非侵入性探测技术,核磁共振波谱在化学、生物和生命科学等学科有着广泛的应用。尤其是二维J分解谱,在两个独立的维度上分别揭示化学位移和J偶合信息,是最重要的核磁共振技术之一。传统二维J分解谱[1]是通过演化时间不断增加的自旋回波实现的。因此,传统二维J分解谱通常需要长的采样时间,从而不适用于监控实时化学反应和发展多维核磁共振谱图。此外,由生物组织固有的磁化率不均匀导致的磁场不均匀通常掩

＜正＞EC-NMR联用技术为研究分子氧化还原机理及其代谢过程提供了一种原位无损的有效研究途径。近年来吸引了大量学者的关注[1]。然而由于EC反应常常产生不稳定中间产物、与产物易造成信号重叠,难以被NMR实时监测;再者EC电解池放置在磁场区域,由于电极和电解液磁化率的不同导致磁场均匀性下降,进而产生信号增宽、磁场灵敏度和分辨率下

磁共振（NMR）多维谱相比于一维谱,拓展了谱峰的空间分布范围,提高了谱图的分辨能力;且多维谱可以提供额外与分子结构相关的波谱信息,是分子结构解析的重要工具。然而,采样时间则一直是限制NMR多维谱实际应用的一个重要因素。另外,随NMR波谱应用的不断拓展和深入,对NMR波谱的方法鲁棒性和谱图参数表现也提出更高的要求。本论文的主要研究内容包括两方面:1.开发NMR快速多维谱新方法,加速获取高质量的磁共振多维谱数据;2.设计新型高分辨磁共振多维谱脉冲序列,致力于在不同应用场合下有效地获取高分辨波谱信息。具体可分为以下几个部分:一、回波链采样可用于单扫描采集NMR二维J分解谱,但所获得谱图在化学位移维会经历很严重的截断效应。本文通过引入线性预测数据后处理方法,可以有效消除回波链采样数据中的截断效应,大幅改善谱图分辨率和信噪比。从而将一张质量良好的二维J分解谱的采集时间从数分钟缩短到1秒以内。二、基于层选激发的选择相干转移空间编码方法可以实现NMR二维相关谱的单扫描超快速采集。然而,谱图中提供耦合网络信息的交叉峰信号可能会受到邻近强对角峰及其拖尾信号的干扰而变得难以识别。本文在选择相干转移脉冲序列基础上,针对性地引入同样基于层选激发的对角峰抑制方法,可实现对超快速二维相关谱中对角峰信号的有效压制,改善交叉峰信号的识别和解析。三、J耦合常数包含重要的分子结构信息。但对于复杂耦合体系中J耦合常数的提取则会因为拥挤的谱峰分布和复杂的J裂峰模式而变得越加困难。本文通过结合二维谱间接维恒时演化与选择性J翻转,设计了一种新型二维选择性J分解谱序列。所采集到谱图会在间接维呈现与感兴趣核相关且分离的J裂峰信息,从而实现复杂J耦合裂峰的分解和J耦合常数的特异性提取。该方法与其他同类方法对比,在灵敏度上存在优势,且简单易行。四、不均匀磁场会引起谱线增宽,导致有效波谱信息的丢失。自旋回波相关谱可以在不均匀磁场下获取相互耦合的自旋核之间高分辨率的化学位移差值信息,而回波链采样则可以获取高分辨率的J耦合裂峰信息。本文将两个脉冲序列模块结合,致力于在强不均匀磁场下获取高分辨二维类J分解谱。另外,通过引入组合脉冲,新序列有望可以应用于磁体外检测等同时存在B0和B1磁场不均匀性的场合。

Diffusion-ordered nuclear magnetic resonance spectroscopy (DOSY) plays a vital role in mixture studies. However, its applications to complex mixture samples are generally limited by spectral congestion along the chemical shift domain caused by extensive J coupling networks and abundant compounds. Herein, we develop the in-phase multidimensional DOSY strategy for complex mixture analyses by simultaneously revealing molecular self-diffusion behaviors and multiplet structures with optimal spectral resolution. As a proof of concept, two pure shift-based three-dimensional (3D) DOSY protocols are proposed to record high-resolution 3D spectroscopic view with separated mixture components and their resolved multiplet coupling structures, thus suitable for analyzing complex mixtures that contain abundant compounds and complicated molecular structures, even under adverse magnetic field conditions. Therefore, this study shows a promising tool for component analyses and multiplet structure studies on practical mixture samples. © 2022 American Chemical Society.