Magnetic Resonance Letters最新文献_第10页

Prospects of borehole NMR instruments and applications 钻孔核磁共振仪器及其应用前景

Magnetic Resonance Letters Pub Date : 2022-11-01 DOI: 10.1016/j.mrl.2022.08.002

Sihui Luo , Jiangfeng Guo , Lizhi Xiao

引用次数: 2

Monitoring Cr(VI) photoreduction at different depths by operando low-field NMR relaxometry 利用低场核磁共振弛豫法监测不同深度下的Cr(VI)光还原

Magnetic Resonance Letters Pub Date : 2022-08-01 DOI: 10.1016/j.mrl.2022.06.005

Beibei Xu, Jingxian Dong, Xuelu Wang, Yefeng Yao

{"title":"Monitoring Cr(VI) photoreduction at different depths by operando low-field NMR relaxometry","authors":"Beibei Xu, Jingxian Dong, Xuelu Wang, Yefeng Yao","doi":"10.1016/j.mrl.2022.06.005","DOIUrl":"10.1016/j.mrl.2022.06.005","url":null,"abstract":"<div>Chromium (VI) (Cr(VI)), a toxic metal ion, is widely present in industrial wastewater. To reduce the contamination of Cr(VI), many technologies for the photocatalytic reduction of Cr(VI) to Cr(III) have been developed in the past decades. However, the practical application of photocatalysts for the reduction of Cr(VI) in wastewater treatment is often hindered by the complicated photoreduction processes due to the sedimentation and stratification of catalyst particles that present during the treatment of the wastewater. Probing and understanding the influences of the sedimentation and stratification of the catalyst particles on the photoreduction processes are long-term challenges in the field. Herein, we demonstrate that this issue can be solved by using layer location integrated low-field time-domain nuclear magnetic resonance (LF-NMR) relaxometry. With paramagnetic Cr (III) cation as the molecular probe, we successfully monitored the Cr(VI) photoreduction processes by operando probing the 1H T2 relaxation time of the photoreduction systems. The influences of catalyst sedimentation and the light wavelength on photocatalysis were studied and discussed. The results showed the great potential of LF-NMR relaxometry in the study of Cr (VI) photoreduction processes during industrial wastewater treatments.</div>","PeriodicalId":93594,"journal":{"name":"Magnetic Resonance Letters","volume":"2 3","pages":"Pages 170-176"},"PeriodicalIF":0.0,"publicationDate":"2022-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S2772516222000249/pdfft?md5=c2fa1b08029b7ac439a8ae39f5523977&pid=1-s2.0-S2772516222000249-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42430857","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: 1

Exploring the intercalation chemistry of layered yttrium hydroxides by 13C solid-state NMR spectroscopy 13C固体核磁共振光谱法研究层状氢氧钇的插层化学性质

Magnetic Resonance Letters Pub Date : 2022-08-01 DOI: 10.1016/j.mrl.2022.03.001

Yanxin Liu, Shijia Jiang, Jun Xu

{"title":"Exploring the intercalation chemistry of layered yttrium hydroxides by 13C solid-state NMR spectroscopy","authors":"Yanxin Liu, Shijia Jiang, Jun Xu","doi":"10.1016/j.mrl.2022.03.001","DOIUrl":"10.1016/j.mrl.2022.03.001","url":null,"abstract":"<div>Layered rare earth hydroxides (LREHs) are a novel class of two-dimensional materials with potential applications in various fields. The exchange reactions with organic anions are typically the first step for the functionalization of LREHs. Although the laminar structures seem to be clear for anion-exchanged compounds, the state of intercalated organic anions and their interactions with cationic rare earth hydroxide layers remain unclear. Herein, we demonstrate that the use of 13C solid-state nuclear magnetic resonance (ssNMR) spectroscopy enables to extract key information on the state of intercalated organic anions such as their local chemical environment, stacking, and dynamics, which are often difficult or impossible to obtain previously. In combination with powder X-ray diffraction and ab initio density functional theory calculations, the intercalation chemistry of two representative layered yttrium hydroxides with selected monovalent organic anions was studied in detail. The products can undergo secondary exchange with a divalent organic anion, depending on the match between the basal spacing of two phases, i.e., the replacement of benzenesulfonate (BS−), 2,4-dimethylbenzene sulfonate (DMBS−), and 4-ethylbenzene sulfonate (EBS−) with 2,6-naphthalene disulfonate (NDS2−) is allowed due to the insignificant change in basal spacing after exchange, while the replacement of very long dodecyl benzene sulfonate (DBS−) and dodecyl sulfate (DS−) with NDS2− is forbidden. The results therefore provide valuable insights into the structure-property relationships of LREH-based functional materials.</div>","PeriodicalId":93594,"journal":{"name":"Magnetic Resonance Letters","volume":"2 3","pages":"Pages 186-194"},"PeriodicalIF":0.0,"publicationDate":"2022-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S2772516222000043/pdfft?md5=ba27458e271fce4405930a3198b119a6&pid=1-s2.0-S2772516222000043-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47318710","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

On the use of cross polarization in solid-state NMR: 1H spin-lock versus adiabatic demagnetization in the rotating frame 关于交叉极化在固态NMR中的应用：旋转框架中的1H自旋锁定与绝热消磁

Magnetic Resonance Letters Pub Date : 2022-08-01 DOI: 10.1016/j.mrl.2022.07.001

Yuchen Li , Shengyu Zhang , Ze Wu , Xinhua Peng , Riqiang Fu

{"title":"On the use of cross polarization in solid-state NMR: 1H spin-lock versus adiabatic demagnetization in the rotating frame","authors":"Yuchen Li , Shengyu Zhang , Ze Wu , Xinhua Peng , Riqiang Fu","doi":"10.1016/j.mrl.2022.07.001","DOIUrl":"10.1016/j.mrl.2022.07.001","url":null,"abstract":"<div>Cross polarization (CP) is a widely used solid-state nuclear magnetic resonance (NMR) technique for enhancing the polarization of dilute S spins from much larger polarization of abundant I spins such as 1H. To achieve such a polarization transfer, the I spin should either be spin-locked or be converted to the dipolar ordered state through adiabatic demagnetization in the rotating frame. In this work, we analyze the spin dynamics of the Hartmann-Hahn CP (HHCP) utilizing the 1H spin-locking, and the dipolar-order CP (DOCP) having the 1H adiabatic demagnetization. We further propose an adiabatic demagnetization CP (ADCP) where a constant radio-frequency pulse is applied on the S spin while 1H is adiabatically demagnetized. Our analyses indicate that ADCP utilizes the adiabatic passage to effectively achieve the polarization transfer from the 1H to S spins. In addition, the dipolar ordered state generated during the 1H demagnetization process could also be converted into the observable S polarization through DOCP, further enhancing the polarized signals. It is shown by both static and magic-angle-spinning (MAS) NMR experiments that ADCP has dramatically broadened the CP matching condition over the other CP schemes. Various samples have been used to demonstrate the polarization transfer efficiency of this newly proposed ADCP scheme.</div>","PeriodicalId":93594,"journal":{"name":"Magnetic Resonance Letters","volume":"2 3","pages":"Pages 147-158"},"PeriodicalIF":0.0,"publicationDate":"2022-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S2772516222000262/pdfft?md5=8863e949f7f57c4885b1d4fe83f7d2ed&pid=1-s2.0-S2772516222000262-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47395050","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

A green route for the preparation of layered double hydroxides from basic magnesium carbonate 碱性碳酸镁制备层状双氢氧化物的绿色途径

Magnetic Resonance Letters Pub Date : 2022-08-01 DOI: 10.1016/j.mrl.2022.06.004

Li Jin , Xiaoyuan Zhou , Juan Wen , Luming Peng

引用次数: 3

Specific protein-urea interactions 特异性蛋白质-尿素相互作用

Magnetic Resonance Letters Pub Date : 2022-08-01 DOI: 10.1016/j.mrl.2022.06.003

Zhi Wei Wong, Daiwen Yang

{"title":"Specific protein-urea interactions","authors":"Zhi Wei Wong, Daiwen Yang","doi":"10.1016/j.mrl.2022.06.003","DOIUrl":"10.1016/j.mrl.2022.06.003","url":null,"abstract":"<div>The mechanism of urea's action in protein denaturation remains largely unknown. To provide an experimental basis for molecular dynamics (MD) simulations on urea-protein interactions, we investigated the effect of urea on human intestinal fatty acid binding protein (hIFABP) by nuclear magnetic resonance (NMR). Hydrogen-deuterium exchange (HDX) rates at ≤ 2 M urea indicate that urea affects hIFABP in a residue-specific manner via direct urea-protein interactions and preferentially weakens hydrogen bonds between highly protected amides. Residue-specific effects of urea on NMR peak intensities and chemical shifts further support the presence of direct urea-protein interactions. Two-dimensional (2D) water-rotating frame Overhauser enhancement (ROE) data shows one protein-bound water molecule in contact with Val66 and Trp82, one putative bound water molecule in interaction with Thr76 and E-F loop, and that urea at low concentrations cannot displace these protein-bound water molecules. Our urea-nuclear Overhauser effect (NOE) experiments using 15N-urea further show no tightly protein-bound urea molecules. Our results thus suggest specific, but weak or transient, urea-protein interactions, supporting the direct interaction model of urea denaturation.</div>","PeriodicalId":93594,"journal":{"name":"Magnetic Resonance Letters","volume":"2 3","pages":"Pages 131-138"},"PeriodicalIF":0.0,"publicationDate":"2022-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S2772516222000225/pdfft?md5=015cd3693d85df00a369ca62ecbac447&pid=1-s2.0-S2772516222000225-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44886776","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

Active shim coils design for Halbach magnet based on inverse boundary element method 基于逆边界元法的Halbach磁体有源补偿线圈设计

Magnetic Resonance Letters Pub Date : 2022-08-01 DOI: 10.1016/j.mrl.2022.06.001

Yajie Xu , Feng Wang , Ya Wang , Peng Yu , Jingzhong Zhang , Xiaodong Yang

{"title":"Active shim coils design for Halbach magnet based on inverse boundary element method","authors":"Yajie Xu , Feng Wang , Ya Wang , Peng Yu , Jingzhong Zhang , Xiaodong Yang","doi":"10.1016/j.mrl.2022.06.001","DOIUrl":"10.1016/j.mrl.2022.06.001","url":null,"abstract":"<div>With advantages of small volume, high field strength, and compact stray field, the Halbach array magnet is of great potential in desktop NMR applications. However, field inhomogeneity poses a main obstacle to its applications. Active shimming is necessary for improving the field homogeneity. An active shim coil design method for cylindrical Halbach magnet based on inverse boundary element method (iBEM) is introduced in this work. Shim coils targeting 1st∼3rd and Z4/Z5/Z6 spherical harmonic (SH) terms were designed with constraints of field accuracy, resistance, inductance, and current density. Wire loops and symmetric property influence were discussed to further improve the performance of high-order shim coils. Finally, with the prototype of the shim coils constructed, field pattern and SH transformation proved that the coils designed could fit the target SH distribution, though contamination from low-order components existed in high-order terms. A practical shimming experiment on the Halbach magnet has improved the homogeneity from 40.3 ppm to 3.8 ppm in radius 2.5 mm, height 5 mm cylindrical sample space, verifying the coils' compensation ability. This work provides a flexible inverse coil design method for cylindrical Halbach magnet and discusses the high-order shim coil design and implementation, which is potential in nuclear magnetic resonance applications based on Halbach magnet arrays.</div>","PeriodicalId":93594,"journal":{"name":"Magnetic Resonance Letters","volume":"2 3","pages":"Pages 159-169"},"PeriodicalIF":0.0,"publicationDate":"2022-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S2772516222000201/pdfft?md5=8401cc79b16c28e9ff0ef1fd75c6ec05&pid=1-s2.0-S2772516222000201-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48625912","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: 2

Conformational dynamics in GPCR signaling by NMR 核磁共振研究GPCR信号的构象动力学

Magnetic Resonance Letters Pub Date : 2022-08-01 DOI: 10.1016/j.mrl.2022.06.006

Yunfei Hu , Changwen Jin

引用次数: 1

NMR used to study the side-reactions between peroxides and antioxidants during the reactive extrusion process of the impact polypropylene 利用核磁共振技术研究了冲击聚丙烯反应挤出过程中过氧化物与抗氧化剂之间的副反应

Magnetic Resonance Letters Pub Date : 2022-05-01 DOI: 10.1016/j.mrl.2021.09.003

Chunfa Li , Ting Huang , Yubin Bao , Zhe Chen , Guangxin Lin

{"title":"NMR used to study the side-reactions between peroxides and antioxidants during the reactive extrusion process of the impact polypropylene","authors":"Chunfa Li , Ting Huang , Yubin Bao , Zhe Chen , Guangxin Lin","doi":"10.1016/j.mrl.2021.09.003","DOIUrl":"10.1016/j.mrl.2021.09.003","url":null,"abstract":"<div>Side reaction pathways are observed to occur between antioxidants and peroxide during the processing of multiple resin grades mediated by controlled peroxide-induced degradation of impact polypropylene. In the present work, the reaction mechanism and main by-products between antioxidants and peroxides were investigated. The results demonstrate that peroxides greatly accelerate the decomposition reactions, and the free radicals formed from peroxide decomposition react with, for example, the antioxidant AO1010 to produce dehydrogenation of phenyl propionic unit(s) at the α position (cinnamic acid ester moiety), which generates a conjugated system leading to the increased color of the product. It is the first time to confirm the cinnamic acid moiety's existence and report its NMR data. Further, this work confirms the dehydrogenation mechanism by comparison with different sterically hindered phenolic antioxidants. It also systematically summarizes the oxidation and degradation mechanism of AO168 and AO1010 under air and peroxide environments, respectively. Based on present study, clear guidelines are obtained to improve the quality of polymeric products, especially the appearance and stability, during product development.</div>","PeriodicalId":93594,"journal":{"name":"Magnetic Resonance Letters","volume":"2 2","pages":"Pages 91-106"},"PeriodicalIF":0.0,"publicationDate":"2022-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S2772516221000292/pdfft?md5=81dd2cdf7901c0b843f73e7c220af51c&pid=1-s2.0-S2772516221000292-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48817976","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

Recent progress in fragment-based drug discovery facilitated by NMR spectroscopy 核磁共振波谱促进基于片段的药物发现的最新进展

Magnetic Resonance Letters Pub Date : 2022-05-01 DOI: 10.1016/j.mrl.2021.100025

Lei Wang , Jia Gao , Rongsheng Ma , Yaqian Liu , Mingqing Liu , Fumei Zhong , Jie Hu , Shuju Li , Jihui Wu , Hualiang Jiang , Jiahai Zhang , Ke Ruan

引用次数: 3