Pub Date : 2024-04-12DOI: 10.1016/j.jmr.2024.107671
Martin C. Korzeczek , Laurynas Dagys , Christoph Müller , Benedikt Tratzmiller , Alon Salhov , Tim Eichhorn , Jochen Scheuer , Stephan Knecht , Martin B. Plenio , Ilai Schwartz
Nuclear spin hyperpolarization techniques, such as dynamic nuclear polarization (DNP) and parahydrogen-induced polarization (PHIP), have revolutionized nuclear magnetic resonance and magnetic resonance imaging. In these methods, a readily available source of high spin order, either electron spins in DNP or singlet states in hydrogen for PHIP, is brought into close proximity with nuclear spin targets, enabling efficient transfer of spin order under external quantum control. Despite vast disparities in energy scales and interaction mechanisms between electron spins in DNP and nuclear singlet states in PHIP, a pseudo-spin formalism allows us to establish an intriguing equivalence. As a result, the important low-field polarization transfer regime of PHIP can be mapped onto an analogous system equivalent to pulsed-DNP. This establishes a correspondence between key polarization transfer sequences in PHIP and DNP, facilitating the transfer of sequence development concepts. This promises fresh insights and significant cross-pollination between DNP and PHIP polarization sequence developers.
{"title":"Towards a unified picture of polarization transfer — pulsed DNP and chemically equivalent PHIP","authors":"Martin C. Korzeczek , Laurynas Dagys , Christoph Müller , Benedikt Tratzmiller , Alon Salhov , Tim Eichhorn , Jochen Scheuer , Stephan Knecht , Martin B. Plenio , Ilai Schwartz","doi":"10.1016/j.jmr.2024.107671","DOIUrl":"https://doi.org/10.1016/j.jmr.2024.107671","url":null,"abstract":"<div><p>Nuclear spin hyperpolarization techniques, such as dynamic nuclear polarization (DNP) and parahydrogen-induced polarization (PHIP), have revolutionized nuclear magnetic resonance and magnetic resonance imaging. In these methods, a readily available source of high spin order, either electron spins in DNP or singlet states in hydrogen for PHIP, is brought into close proximity with nuclear spin targets, enabling efficient transfer of spin order under external quantum control. Despite vast disparities in energy scales and interaction mechanisms between electron spins in DNP and nuclear singlet states in PHIP, a pseudo-spin formalism allows us to establish an intriguing equivalence. As a result, the important low-field polarization transfer regime of PHIP can be mapped onto an analogous system equivalent to pulsed-DNP. This establishes a correspondence between key polarization transfer sequences in PHIP and DNP, facilitating the transfer of sequence development concepts. This promises fresh insights and significant cross-pollination between DNP and PHIP polarization sequence developers.</p></div>","PeriodicalId":16267,"journal":{"name":"Journal of magnetic resonance","volume":"362 ","pages":"Article 107671"},"PeriodicalIF":2.2,"publicationDate":"2024-04-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S1090780724000557/pdfft?md5=a3a0f38ec0c330f9b0f6062aa2e958f1&pid=1-s2.0-S1090780724000557-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140549906","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-04-10DOI: 10.1016/j.jmr.2024.107670
Ludovica M. Epasto , Thibaud Maimbourg , Alberto Rosso , Dennis Kurzbach
We reveal an interplay between temperature and radical concentration necessary to establish thermal mixing (TM) as an efficient dynamic nuclear polarization (DNP) mechanism. We conducted DNP experiments by hyperpolarizing widely used DNP samples, i.e., sodium pyruvate-1-13C in water/glycerol mixtures at varying nitroxide radical (TEMPOL) concentrations and microwave irradiation frequencies, measuring proton and carbon-13 spin temperatures. Using a cryogen consumption-free prototype-DNP apparatus, we could probe cryogenic temperatures between 1.5 and 6.5 K, i.e., below and above the boiling point of liquid helium. We identify two mechanisms for the breakdown of TM: (i) Anderson type of quantum localization for low radical concentration, or (ii) quantum Zeno localization occurring at high temperature. This observation allowed us to reconcile the recent diverging observations regarding the relevance of TM as a DNP mechanism by proposing a unifying picture and, consequently, to find a trade-off between radical concentration and electron relaxation times, which offers a pathway to improve experimental DNP performance based on TM.
{"title":"Unified understanding of the breakdown of thermal mixing dynamic nuclear polarization: The role of temperature and radical concentration","authors":"Ludovica M. Epasto , Thibaud Maimbourg , Alberto Rosso , Dennis Kurzbach","doi":"10.1016/j.jmr.2024.107670","DOIUrl":"https://doi.org/10.1016/j.jmr.2024.107670","url":null,"abstract":"<div><p>We reveal an interplay between temperature and radical concentration necessary to establish thermal mixing (TM) as an efficient dynamic nuclear polarization (DNP) mechanism. We conducted DNP experiments by hyperpolarizing widely used DNP samples, i.e., sodium pyruvate-1-<sup>13</sup>C in water/glycerol mixtures at varying nitroxide radical (TEMPOL) concentrations and microwave irradiation frequencies, measuring proton and carbon-13 spin temperatures. Using a cryogen consumption-free prototype-DNP apparatus, we could probe cryogenic temperatures between 1.5 and 6.5 K, i.e., below and above the boiling point of liquid helium. We identify two mechanisms for the breakdown of TM: (i) Anderson type of quantum localization for low radical concentration, or (ii) quantum Zeno localization occurring at high temperature. This observation allowed us to reconcile the recent diverging observations regarding the relevance of TM as a DNP mechanism by proposing a unifying picture and, consequently, to find a trade-off between radical concentration and electron relaxation times, which offers a pathway to improve experimental DNP performance based on TM.</p></div>","PeriodicalId":16267,"journal":{"name":"Journal of magnetic resonance","volume":"362 ","pages":"Article 107670"},"PeriodicalIF":2.2,"publicationDate":"2024-04-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S1090780724000545/pdfft?md5=55d1b85fa26a6684d12c60f8735a15b3&pid=1-s2.0-S1090780724000545-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140543458","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-04-10DOI: 10.1016/j.jmr.2024.107677
Alexander A. Nevzorov, Antonin Marek, Sergey Milikisiyants, Alex I. Smirnov
One of the most essential prerequisites for the development of pulse Dynamic Nuclear Polarization (DNP) is the ability to generate high-power coherent mm-wave pulses at the electron precession frequencies corresponding to the magnetic fields of modern high-resolution NMR spectrometers. As a major step towards achieving this goal, an Extended Interaction Klystron (EIK) pulse amplifier custom-built by the Communications and Power Industries, Inc. and producing up to 140 W at 197.8 GHz, was integrated with in-house built NMR/DNP/EPR spectrometer operating at 7 T magnetic field. The spectrometer employs a Thomas Keating, Ltd. quasioptical bridge to direct mm-waves into a homebuilt DNP probe incorporating photonic bandgap (PBG) resonators to further boost electronic B1e fields. Three-pulse electron spin echo nutation experiments were employed to characterize the B1e fields at the sample by operating the homodyne 198 GHz bridge in an induction mode. Room-temperature experiments with a single-crystal high-pressure, high-temperature (HPHT) diamond and a polystyrene film doped with BDPA radical yielded < 9 ns π/2 pulses at ca. 50 W specified EIK output at the corresponding resonance frequencies and the PBG resonator quality factor of Q≈300. DNP experiments carried out in a “gated” mode by supplying 20 μs mm-wave pulses every 1 ms yielded 13C solid-effect DNP with gains up to 20 for the polystyrene-BDPA sample at natural 13C abundance. For a single-crystal HPHT diamond, the gated DNP mode yielded almost the same 13C enhancement as a low-power continuous wave (CW) mode at 0.4 W, whereas no DNP effect was observed for the BDPA/polystyrene sample in the latter case. To illustrate the versatility of our upgraded DNP spectrometer, room-temperature Overhauser DNP enhancements of 7–14 for 31P NMR signal were demonstrated using a liquid droplet of 1 M tri-phenyl phosphine co-dissolved with 100 mM of BDPA in toluene‑d8.
{"title":"High-frequency high-power DNP/EPR spectrometer operating at 7 T magnetic field","authors":"Alexander A. Nevzorov, Antonin Marek, Sergey Milikisiyants, Alex I. Smirnov","doi":"10.1016/j.jmr.2024.107677","DOIUrl":"https://doi.org/10.1016/j.jmr.2024.107677","url":null,"abstract":"<div><p>One of the most essential prerequisites for the development of pulse Dynamic Nuclear Polarization (DNP) is the ability to generate high-power coherent mm-wave pulses at the electron precession frequencies corresponding to the magnetic fields of modern high-resolution NMR spectrometers. As a major step towards achieving this goal, an Extended Interaction Klystron (EIK) pulse amplifier custom-built by the Communications and Power Industries, Inc. and producing up to 140 W at 197.8 GHz, was integrated with in-house built NMR/DNP/EPR spectrometer operating at 7 T magnetic field. The spectrometer employs a Thomas Keating, Ltd. quasioptical bridge to direct mm-waves into a homebuilt DNP probe incorporating photonic bandgap (PBG) resonators to further boost electronic <em>B</em><sub>1e</sub> fields. Three-pulse electron spin echo nutation experiments were employed to characterize the <em>B</em><sub>1e</sub> fields at the sample by operating the homodyne 198 GHz bridge in an induction mode. Room-temperature experiments with a single-crystal high-pressure, high-temperature (HPHT) diamond and a polystyrene film doped with BDPA radical yielded < 9 ns π/2 pulses at <em>ca</em>. 50 W specified EIK output at the corresponding resonance frequencies and the PBG resonator quality factor of <em>Q</em>≈300. DNP experiments carried out in a “gated” mode by supplying 20 μs mm-wave pulses every 1 ms yielded <sup>13</sup>C solid-effect DNP with gains up to 20 for the polystyrene-BDPA sample at natural <sup>13</sup>C abundance. For a single-crystal HPHT diamond, the gated DNP mode yielded almost the same <sup>13</sup>C enhancement as a low-power continuous wave (CW) mode at 0.4 W, whereas no DNP effect was observed for the BDPA/polystyrene sample in the latter case. To illustrate the versatility of our upgraded DNP spectrometer, room-temperature Overhauser DNP enhancements of 7–14 for <sup>31</sup>P NMR signal were demonstrated using a liquid droplet of 1 M <em>tri</em>-phenyl phosphine co-dissolved with 100 mM of BDPA in toluene‑<em>d</em><sub>8</sub>.</p></div>","PeriodicalId":16267,"journal":{"name":"Journal of magnetic resonance","volume":"362 ","pages":"Article 107677"},"PeriodicalIF":2.2,"publicationDate":"2024-04-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140558166","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-04-09DOI: 10.1016/j.jmr.2024.107669
Bart de Vos , Rob Remis , Andrew Webb
MRI systems have a thin conducting layer placed between the gradient and RF coils, this acts as a shield at the RF-frequency, minimizing noise coupled into the experiment, and decreasing the coupling between the RF and gradient coils. Ideally, this layer should be transparent to the gradient fields to reduce eddy currents. In this work the design of such a shield, specifically for low-field point-of-care Halbach based MRI devices, is discussed. A segmented double layer shield is designed and constructed based on eddy current simulations. Subsequently, the performance of the improved shield is compared to a reference shield by measuring the eddy current decay times as well as using noise measurements. A maximum reduction factor of 2.9 in the eddy current decay time is observed. The segmented shield couples in an equivalent amount of noise when compared to the unsegmented reference shield. Turbo spin echo images of a phantom and the brain of a healthy volunteer show improvements in terms of blurring using the segmented shield.
{"title":"Segmented RF shield design to minimize eddy currents for low-field Halbach MRI systems","authors":"Bart de Vos , Rob Remis , Andrew Webb","doi":"10.1016/j.jmr.2024.107669","DOIUrl":"https://doi.org/10.1016/j.jmr.2024.107669","url":null,"abstract":"<div><p>MRI systems have a thin conducting layer placed between the gradient and RF coils, this acts as a shield at the RF-frequency, minimizing noise coupled into the experiment, and decreasing the coupling between the RF and gradient coils. Ideally, this layer should be transparent to the gradient fields to reduce eddy currents. In this work the design of such a shield, specifically for low-field point-of-care Halbach based MRI devices, is discussed. A segmented double layer shield is designed and constructed based on eddy current simulations. Subsequently, the performance of the improved shield is compared to a reference shield by measuring the eddy current decay times as well as using noise measurements. A maximum reduction factor of 2.9 in the eddy current decay time is observed. The segmented shield couples in an equivalent amount of noise when compared to the unsegmented reference shield. Turbo spin echo images of a phantom and the brain of a healthy volunteer show improvements in terms of blurring using the segmented shield.</p></div>","PeriodicalId":16267,"journal":{"name":"Journal of magnetic resonance","volume":"362 ","pages":"Article 107669"},"PeriodicalIF":2.2,"publicationDate":"2024-04-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S1090780724000533/pdfft?md5=772bb53db7d3ab1032d0848b4783c66e&pid=1-s2.0-S1090780724000533-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140540099","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-04-09DOI: 10.1016/j.jmr.2024.107673
Franziska Theiss, Jonas Lins, Jan Kergassner, Laura Wienands, Sonja Döller, Gerd Buntkowsky
The rapid advancement of parahydrogen-induced hyperpolarization (PHIP) and its diverse array of applications highlights the critical need for enhanced signals in both 1H NMR and heteronuclear NMR spectroscopy. Simultaneously, there is an increasing interest in utilizing benchtop NMR analysis across various laboratory settings. However, due to their lower magnetic fields, benchtop NMR spectrometers inherently produce weaker signal intensities. Here, PHIP is a well-established solution to this challenge. Consequently, we are expanding our cost-effective PHIP setup from a high-field NMR spectrometer (11.7 T) to include an additional benchtop NMR spectrometer (1.4 T), thereby enabling concurrent execution of PHIP experiments and measurements. Through the implementation of automated experimental protocols, we aim to minimize experiment time while increasing reproducibility. In this work, a non-isotope labelled propargyl alcohol sample is used at low concentrations to demonstrate our setup’s capabilities. It could be shown that single-scan PASADENA experiments can be run with comparable signal enhancements at the benchtop as well as the high-field spectrometer. At 1.4 T, fully automated PHIP pseudo-2D measurements will also be demonstrated. Additionally, two different field profiles for the spin-order transfer of p-H2 to 13C at zero- to ultralow fields are elaborated upon. The setup facilitates the measurement of carbon signal enhancement of more than 2000 on the benchtop NMR spectrometer, employing a straightforward one-pulse, one-scan experiment.
{"title":"Two fields are better than one – A multifunctional (semi)automated setup for quantitative measurements of parahydrogen-induced signal enhancement at low and high fields","authors":"Franziska Theiss, Jonas Lins, Jan Kergassner, Laura Wienands, Sonja Döller, Gerd Buntkowsky","doi":"10.1016/j.jmr.2024.107673","DOIUrl":"https://doi.org/10.1016/j.jmr.2024.107673","url":null,"abstract":"<div><p>The rapid advancement of parahydrogen-induced hyperpolarization (PHIP) and its diverse array of applications highlights the critical need for enhanced signals in both <sup>1</sup>H NMR and heteronuclear NMR spectroscopy. Simultaneously, there is an increasing interest in utilizing benchtop NMR analysis across various laboratory settings. However, due to their lower magnetic fields, benchtop NMR spectrometers inherently produce weaker signal intensities. Here, PHIP is a well-established solution to this challenge. Consequently, we are expanding our cost-effective PHIP setup from a high-field NMR spectrometer (11.7 T) to include an additional benchtop NMR spectrometer (1.4 T), thereby enabling concurrent execution of PHIP experiments and measurements. Through the implementation of automated experimental protocols, we aim to minimize experiment time while increasing reproducibility. In this work, a non-isotope labelled propargyl alcohol sample is used at low concentrations to demonstrate our setup’s capabilities. It could be shown that single-scan PASADENA experiments can be run with comparable signal enhancements at the benchtop as well as the high-field spectrometer. At 1.4 T, fully automated PHIP pseudo-2D measurements will also be demonstrated. Additionally, two different field profiles for the spin-order transfer of p-H<sub>2</sub> to <sup>13</sup>C at zero- to ultralow fields are elaborated upon. The setup facilitates the measurement of carbon signal enhancement of more than 2000 on the benchtop NMR spectrometer, employing a straightforward one-pulse, one-scan experiment.</p></div>","PeriodicalId":16267,"journal":{"name":"Journal of magnetic resonance","volume":"362 ","pages":"Article 107673"},"PeriodicalIF":2.2,"publicationDate":"2024-04-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S1090780724000570/pdfft?md5=52770f9f6675850643abaf6a23d588fa&pid=1-s2.0-S1090780724000570-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140540110","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Two-dimensional (2D) J-resolved spectroscopy provides valuable information on J-coupling constants for molecular structure analysis by resolving one-dimensional (1D) spectra. However, it is challenging to decipher the J-coupling connectivity in 2D J-resolved spectra because the J-coupling connectivity cannot be directly provided. In addition, 2D homonuclear correlation spectroscopy (COSY) can directly elucidate molecular structures by tracking the J-coupling connectivity between protons. However, this method is limited by the problem of spectral peak crowding and is only suitable for simple sample systems. To fully understand the intuitive coupling relationship and coupling constant information, we propose a three-dimensional (3D) COSY method called CTCOSY-JRES (Constant-Time COrrelation SpectroscopY and J-REsolved Spectroscopy) in this paper. By combining the J-resolved spectrum with the constant-time COSY technique, a doubly decoupled COSY spectrum can be provided while preserving the J-coupling constant along an additional dimension, ensuring high-resolution analysis of J-coupling connectivity and J-coupling information. Moreover, compression sensing and fold-over correction techniques are introduced to accelerate experimental acquisition. The CTCOSY-JRES method has been successfully validated in a variety of sample systems, including industrial, agricultural, and biopharmaceutical samples, revealing complex coupling interactions and providing deeper insights into the resolution of molecular structures.
{"title":"CTCOSY-JRES: A high-resolution three-dimensional NMR method for unveiling J-couplings","authors":"Xiaoqing Lin, Yulei Chen, Chengda Huang, Xiaozhen Feng, Bo Chen, Yuqing Huang, Zhong Chen","doi":"10.1016/j.jmr.2024.107675","DOIUrl":"https://doi.org/10.1016/j.jmr.2024.107675","url":null,"abstract":"<div><p>Two-dimensional (2D) <em>J</em>-resolved spectroscopy provides valuable information on <em>J</em>-coupling constants for molecular structure analysis by resolving one-dimensional (1D) spectra. However, it is challenging to decipher the <em>J</em>-coupling connectivity in 2D <em>J</em>-resolved spectra because the <em>J</em>-coupling connectivity cannot be directly provided. In addition, 2D homonuclear correlation spectroscopy (COSY) can directly elucidate molecular structures by tracking the <em>J</em>-coupling connectivity between protons. However, this method is limited by the problem of spectral peak crowding and is only suitable for simple sample systems. To fully understand the intuitive coupling relationship and coupling constant information, we propose a three-dimensional (3D) COSY method called CTCOSY-<em>J</em>RES (Constant-Time COrrelation SpectroscopY and <em>J</em>-REsolved Spectroscopy) in this paper. By combining the <em>J</em>-resolved spectrum with the constant-time COSY technique, a doubly decoupled COSY spectrum can be provided while preserving the <em>J</em>-coupling constant along an additional dimension, ensuring high-resolution analysis of <em>J</em>-coupling connectivity and <em>J</em>-coupling information. Moreover, compression sensing and fold-over correction techniques are introduced to accelerate experimental acquisition. The CTCOSY-<em>J</em>RES method has been successfully validated in a variety of sample systems, including industrial, agricultural, and biopharmaceutical samples, revealing complex coupling interactions and providing deeper insights into the resolution of molecular structures.</p></div>","PeriodicalId":16267,"journal":{"name":"Journal of magnetic resonance","volume":"362 ","pages":"Article 107675"},"PeriodicalIF":2.2,"publicationDate":"2024-04-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140558162","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-04-06DOI: 10.1016/j.jmr.2024.107674
Justinas Sakas , Dušan Uhrín , Ole W. Sørensen
Proton-detected INADEQUATE NMR experiments are widely used for structure elucidation of small molecules, in particular the implementations that display 13C single-quantum rather than double-quantum frequencies in the indirect dimension of 2D spectra. But unfortunately, such spectra in addition to the desired 1H–13C two-bond correlations also contain HSQC artifacts of comparable magnitude. The redesigned versatile experiment presented in this paper requires no compromise based on different 13C multiplicities and suppresses the HSQC artifacts that are a source of possible spectral misinterpretation. Demonstration of the new method is shown by applications to typical small molecules of different complexity.
{"title":"Clean PDI-1 SQ: Suppression of HSQC artifacts in 2D proton-detected INADEQUATE spectra by pulse sequence redesign","authors":"Justinas Sakas , Dušan Uhrín , Ole W. Sørensen","doi":"10.1016/j.jmr.2024.107674","DOIUrl":"https://doi.org/10.1016/j.jmr.2024.107674","url":null,"abstract":"<div><p>Proton-detected INADEQUATE NMR experiments are widely used for structure elucidation of small molecules, in particular the implementations that display <sup>13</sup>C single-quantum rather than double-quantum frequencies in the indirect dimension of 2D spectra. But unfortunately, such spectra in addition to the desired <sup>1</sup>H–<sup>13</sup>C two-bond correlations also contain HSQC artifacts of comparable magnitude. The redesigned versatile experiment presented in this paper requires no compromise based on different <sup>13</sup>C multiplicities and suppresses the HSQC artifacts that are a source of possible spectral misinterpretation. Demonstration of the new method is shown by applications to typical small molecules of different complexity.</p></div>","PeriodicalId":16267,"journal":{"name":"Journal of magnetic resonance","volume":"362 ","pages":"Article 107674"},"PeriodicalIF":2.2,"publicationDate":"2024-04-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140539946","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-04-01DOI: 10.1016/j.jmr.2024.107662
José M. Algarín , Teresa Guallart-Naval , José Borreguero , Fernando Galve , Joseba Alonso
The open-source console MaRCoS, which stands for “Magnetic Resonance Control System”, combines hardware, firmware and software elements for integral control of Magnetic Resonance Imaging (MRI) scanners. Previous developments have focused on making the system robust and reliable, rather than on users, who have been somewhat overlooked. This work describes a Graphical User Interface (GUI) designed for intuitive control of MaRCoS, as well as compatibility with clinical environments. The GUI is based on an arrangement of tabs and a renewed Application Program Interface (API). Compared to the previous versions, the MaRGE package (“MaRCoS Graphical Environment”) includes new functionalities such as the possibility to export images to standard DICOM formats, create and manage clinical protocols, or display and process image reconstructions, among other features conceived to simplify the operation of MRI scanners. All prototypes in our facilities are commanded by MaRCoS and operated with the new GUI. Here we report on its performance on an experimental 0.2 T scanner designed for hard-tissue, as well as a 72 mT portable scanner presently installed in the radiology department of a large hospital. The possibility to customize, adapt and streamline processes has substantially improved our workflows and overall experience.
{"title":"MaRGE: A graphical environment for MaRCoS","authors":"José M. Algarín , Teresa Guallart-Naval , José Borreguero , Fernando Galve , Joseba Alonso","doi":"10.1016/j.jmr.2024.107662","DOIUrl":"https://doi.org/10.1016/j.jmr.2024.107662","url":null,"abstract":"<div><p>The open-source console MaRCoS, which stands for “Magnetic Resonance Control System”, combines hardware, firmware and software elements for integral control of Magnetic Resonance Imaging (MRI) scanners. Previous developments have focused on making the system robust and reliable, rather than on users, who have been somewhat overlooked. This work describes a Graphical User Interface (GUI) designed for intuitive control of MaRCoS, as well as compatibility with clinical environments. The GUI is based on an arrangement of tabs and a renewed Application Program Interface (API). Compared to the previous versions, the MaRGE package (“MaRCoS Graphical Environment”) includes new functionalities such as the possibility to export images to standard DICOM formats, create and manage clinical protocols, or display and process image reconstructions, among other features conceived to simplify the operation of MRI scanners. All prototypes in our facilities are commanded by MaRCoS and operated with the new GUI. Here we report on its performance on an experimental 0.2 T scanner designed for hard-tissue, as well as a 72 mT portable scanner presently installed in the radiology department of a large hospital. The possibility to customize, adapt and streamline processes has substantially improved our workflows and overall experience.</p></div>","PeriodicalId":16267,"journal":{"name":"Journal of magnetic resonance","volume":"361 ","pages":"Article 107662"},"PeriodicalIF":2.2,"publicationDate":"2024-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S1090780724000466/pdfft?md5=b16f023fb275e84de53d69f4129e9e1c&pid=1-s2.0-S1090780724000466-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140343935","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-04-01DOI: 10.1016/j.jmr.2024.107668
Laouès Guendouz , Sébastien Leclerc , Daniel Canet
The measurement of translational diffusion coefficients by NMR generally makes use basically of two magnetic field gradient pulses separated by a so-called diffusion interval. The magnetic field gradient arises either from the static magnetic field (denoted by B0 used for polarizing the nuclear spins) or from the radio-frequency field (denoted by B1 used for inducing NMR transitions). The B0 method may be hampered by short effective transverse relaxation times (), by important gradient rise and fall times or by eddy currents. This does not occur with B1 gradients. Moreover, the effect of short transverse relaxation times during the gradient pulses is reduced by at least a factor of two. However, for B1 gradients, one might face with the limited volume in which the gradient is uniform and with the effect of short relaxation times which imply to reduce the various intervals in the diffusion experiment (this is as well true for the B0 method). Examples will be given for which the measurement of the diffusion coefficient by B0 gradients turned out to be impossible while a proper result was obtained with B1 gradients as far as a correction taking into account the limited volume is applied, together with a correction about the gradient calibration especially when dealing with samples containing paramagnetic species.
{"title":"NMR measurement of diffusion coefficients by radio-frequency gradients in the case of short relaxation times","authors":"Laouès Guendouz , Sébastien Leclerc , Daniel Canet","doi":"10.1016/j.jmr.2024.107668","DOIUrl":"https://doi.org/10.1016/j.jmr.2024.107668","url":null,"abstract":"<div><p>The measurement of translational diffusion coefficients by NMR generally makes use basically of two magnetic field gradient pulses separated by a so-called diffusion interval. The magnetic field gradient arises either from the static magnetic field (denoted by B<sub>0</sub> used for polarizing the nuclear spins) or from the radio-frequency field (denoted by B<sub>1</sub> used for inducing NMR transitions). The B<sub>0</sub> method may be hampered by short effective transverse relaxation times (<span><math><mrow><msubsup><mi>T</mi><mrow><mn>2</mn></mrow><mrow><mo>∗</mo></mrow></msubsup></mrow></math></span>), by important gradient rise and fall times or by eddy currents. This does not occur with B<sub>1</sub> gradients. Moreover, the effect of short transverse relaxation times during the gradient pulses is reduced by at least a factor of two. However, for B<sub>1</sub> gradients, one might face with the limited volume in which the gradient is uniform and with the effect of short relaxation times which imply to reduce the various intervals in the diffusion experiment (this is as well true for the B<sub>0</sub> method). Examples will be given for which the measurement of the diffusion coefficient by B<sub>0</sub> gradients turned out to be impossible while a proper result was obtained with B<sub>1</sub> gradients as far as a correction taking into account the limited volume is applied, together with a correction about the gradient calibration especially when dealing with samples containing paramagnetic species.</p></div>","PeriodicalId":16267,"journal":{"name":"Journal of magnetic resonance","volume":"361 ","pages":"Article 107668"},"PeriodicalIF":2.2,"publicationDate":"2024-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140346900","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-03-28DOI: 10.1016/j.jmr.2024.107667
Rashik Ahmed , Atul K. Rangadurai , Lisa Ruetz , Martin Tollinger , Christoph Kreutz , Lewis E. Kay
Solution NMR spectroscopy has tremendous potential for providing atomic resolution insights into the interactions between proteins and nucleic acids partitioned into condensed phases of phase-separated systems. However, the highly viscous nature of the condensed phase challenges applications, and in particular, the extraction of quantitative, site-specific information. Here, we present a delayed decoupling-based HMQC pulse sequence for methyl-TROSY studies of ‘client’ proteins and nucleic acids partitioned into ‘scaffold’ proteinaceous phase-separated solvents. High sensitivity and excellent quality spectra are recorded of a nascent form of superoxide dismutase and of a small RNA fragment partitioned into CAPRIN1 condensates.
{"title":"A delayed decoupling methyl-TROSY pulse sequence for atomic resolution studies of folded proteins and RNAs in condensates","authors":"Rashik Ahmed , Atul K. Rangadurai , Lisa Ruetz , Martin Tollinger , Christoph Kreutz , Lewis E. Kay","doi":"10.1016/j.jmr.2024.107667","DOIUrl":"10.1016/j.jmr.2024.107667","url":null,"abstract":"<div><p>Solution NMR spectroscopy has tremendous potential for providing atomic resolution insights into the interactions between proteins and nucleic acids partitioned into condensed phases of phase-separated systems. However, the highly viscous nature of the condensed phase challenges applications, and in particular, the extraction of quantitative, site-specific information. Here, we present a delayed decoupling-based HMQC pulse sequence for methyl-TROSY studies of ‘client’ proteins and nucleic acids partitioned into ‘scaffold’ proteinaceous phase-separated solvents. High sensitivity and excellent quality spectra are recorded of a nascent form of superoxide dismutase and of a small RNA fragment partitioned into CAPRIN1 condensates.</p></div>","PeriodicalId":16267,"journal":{"name":"Journal of magnetic resonance","volume":"362 ","pages":"Article 107667"},"PeriodicalIF":2.2,"publicationDate":"2024-03-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140407964","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}