Journal of magnetic resonance最新文献

{"title":"Surface dielectric resonator for in vivo EPR measurements","authors":"Sergey V. Petryakov ,&nbsp;Maciej M. Kmiec ,&nbsp;Conner S. Ubert ,&nbsp;Victor B. Kassey ,&nbsp;Philip E. Schaner ,&nbsp;Periannan Kuppusamy","doi":"10.1016/j.jmr.2024.107690","DOIUrl":"10.1016/j.jmr.2024.107690","url":null,"abstract":"<div><p>This research report describes a novel surface dielectric resonator (SDR) with a flexible connector for <em>in vivo</em> electron paramagnetic resonance (EPR) spectroscopy. Contrary to the conventional cavity or surface loop-gap resonators, the newly developed SDR is constructed from a ceramic dielectric material, and it is tuned to operate at the L-band frequency band (1.15 GHz) in continuous-wave mode. The SDR is designed to be critically coupled and capable of working with both very lossy samples, such as biological tissues, and non-lossy materials. The SDR was characterized using electromagnetic field simulations, assessed for sensitivity with a B₁ field-perturbation method, and validated with tissue phantoms using EPR measurements. The results showed remarkably higher sensitivity in lossy tissue phantoms than the previously reported multisegment surface-loop resonators. The new SDR can provide potential new insights for advancements in the application of <em>in vivo</em> EPR spectroscopy for biological measurements, including clinical oximetry.</p></div>","PeriodicalId":16267,"journal":{"name":"Journal of magnetic resonance","volume":"362 ","pages":"Article 107690"},"PeriodicalIF":2.2,"publicationDate":"2024-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140768112","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}

{"title":"Frame change technique for phase transient cancellation","authors":"Andrew Stasiuk ,&nbsp;Pai Peng ,&nbsp;Garrett Heller ,&nbsp;Paola Cappellaro","doi":"10.1016/j.jmr.2024.107688","DOIUrl":"https://doi.org/10.1016/j.jmr.2024.107688","url":null,"abstract":"<div><p>The precise control of complex quantum mechanical systems can unlock applications ranging from quantum simulation to quantum computation. Controlling strongly interacting many-body systems often relies on Floquet Hamiltonian engineering that is achieved by fast switching between Hamiltonian primitives via external control. For example, in our solid-state NMR system, we perform quantum simulation by modulating the natural Hamiltonian with control pulses. As the Floquet heating errors scale with the interpulse delay, <span><math><mrow><mi>δ</mi><mi>t</mi></mrow></math></span>, it is favorable to keep <span><math><mrow><mi>δ</mi><mi>t</mi></mrow></math></span> as short as possible, forcing our control pulses to be short duration and high power. Additionally, high-power pulses help to minimize undesirable evolution from occurring during the duration of the pulse. However, such pulses introduce an appreciable phase-transient control error, a form of unitary error. In this work, we detail our ability to diagnose the error, calibrate its magnitude, and correct it for <span><math><mrow><mi>π</mi><mo>/</mo><mn>2</mn></mrow></math></span>-pulses of arbitrary phase. We demonstrate the improvements gained by correcting for the phase transient error, using a method which we call the “frame-change technique”, in a variety of experimental settings of interest. Given that the correction mechanism adds no real control overhead, we recommend that any resonance probe be checked for these phase transient control errors, and correct them using the frame-change technique.</p></div>","PeriodicalId":16267,"journal":{"name":"Journal of magnetic resonance","volume":"362 ","pages":"Article 107688"},"PeriodicalIF":2.2,"publicationDate":"2024-04-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140650734","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}

{"title":"NMR insights into β-Lactamase activity of UVI31+ Protein from Chlamydomonas reinhardtii","authors":"Ashok K. Rout ,&nbsp;Saurabh Gautam ,&nbsp;Vipin Kumar Mishra ,&nbsp;Mandar Bopardikar ,&nbsp;Budheswar Dehury ,&nbsp;Himanshu Singh","doi":"10.1016/j.jmr.2024.107689","DOIUrl":"https://doi.org/10.1016/j.jmr.2024.107689","url":null,"abstract":"<div><p>β-Lactamases (EC 3.5.2.6) confer resistance against β-lactam group-containing antibiotics in bacteria and higher eukaryotes, including humans. Pathogenic bacterial resistance against β-lactam antibiotics is a primary concern for potential therapeutic developments and drug targets. Here, we report putative β-lactamase activity, sulbactam binding (a β-lactam analogue) in the low μM affinity range, and site-specific interaction studies of a 14 kDa UV- and dark-inducible protein (abbreviated as UVI31+, a BolA homologue) from <em>Chlamydomonas reinhartii</em>. Intriguingly, the solution NMR structure of UVI31 + bears no resemblance to other known β-lactamases; however, the sulbactam binding is found at two sites rich in positively charged residues, mainly at the L2 loop regions and the N-terminus. Using NMR spectroscopy, ITC and MD simulations, we map the ligand binding sites in UVI31 + providing atomic-level insights into its β-lactamase activity. Current study is the first report on β-lactamase activity of UVI31+, a BolA analogue, from <em>C. reinhartii</em>. Furthermore, our mutation studies reveal that the active site serine-55 is crucial for β-lactamase activity.</p></div>","PeriodicalId":16267,"journal":{"name":"Journal of magnetic resonance","volume":"362 ","pages":"Article 107689"},"PeriodicalIF":2.2,"publicationDate":"2024-04-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140650688","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}

{"title":"A study of helium-3 nuclear magnetic relaxation mechanism in contact with 20 nm DyF3 nanoparticles","authors":"Adeliya Garaeva,&nbsp;Ekaterina Boltenkova,&nbsp;Kajum Safiullin ,&nbsp;Irina Romanova,&nbsp;Egor Alakshin","doi":"10.1016/j.jmr.2024.107672","DOIUrl":"https://doi.org/10.1016/j.jmr.2024.107672","url":null,"abstract":"<div><p>The spin kinetics of adsorbed and liquid ³He in contact with a mixture of LaF₃ (99.67 %) and DyF₃ (0.33 %) 20 nm powders at temperatures of 1.5–4.2 K in magnetic fields up to 505<!--> <!-->mT was studied by pulsed nuclear magnetic resonance (NMR). Two-component of nuclear magnetic relaxation was observed in the experiment and theoretical relaxation model was proposed. The possible explanation of this phenomena can be carried out by a model that consider the exchange of magnetization of helium-3 nuclei located in the adsorbed layer and in the bulk of the liquid. The proposed relaxation model can be applied to other systems with the strong influence of adsorbed layer.</p></div>","PeriodicalId":16267,"journal":{"name":"Journal of magnetic resonance","volume":"362 ","pages":"Article 107672"},"PeriodicalIF":2.2,"publicationDate":"2024-04-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140631711","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}

{"title":"Optimization of RF coil geometry for NMR/MRI applications using a genetic algorithm","authors":"Techit Tritrakarn ,&nbsp;Masato Takahashi ,&nbsp;Tetsuji Okamura","doi":"10.1016/j.jmr.2024.107685","DOIUrl":"https://doi.org/10.1016/j.jmr.2024.107685","url":null,"abstract":"<div><p>A simulation method that employs a genetic algorithm (GA) for optimizing radio frequency (RF) coil geometry is developed to maximize signal intensity in nuclear magnetic resonance (NMR)/magnetic resonance imaging (MRI) applications. NMR/MRI has a wide range of applications, including medical imaging, and chemical and biological analysis to investigate the structure, dynamics, and interactions of molecules. However, NMR suffers from inherently low signal intensity, which depends on factors related to RF coil geometry. The investigation of coil geometry is crucial for improving signal intensity, leading to a reduction in the number of scans and a shorter total scan time. We have explored a better optimization method by modifying RF coil geometry to maximize signal intensity. The RF coil geometry comprises wire elements, each of which is a small vector representing the current flow, and GA chooses some of the prepared wire elements for optimization. The optimization of a substrate coil with a surface perpendicular to a static field was demonstrated for single-sided NMR system applications while considering various cylindrical sample diameters. A non-optimized and a GA-optimized substrate coil were compared through simulation and experiment to confirm the performance of the GA simulation. The maximum error between simulation and experiment was below 5%, with an average of less than 3%, confirming simulation reliability. The results indicated that the GA improved signal intensity by approximately 10% and reduced the necessary total scan time by around 20%. Finally, we explain the limitations and explore other potential applications of this GA-based simulation method.</p></div>","PeriodicalId":16267,"journal":{"name":"Journal of magnetic resonance","volume":"362 ","pages":"Article 107685"},"PeriodicalIF":2.2,"publicationDate":"2024-04-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140558167","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}

{"title":"Towards a unified picture of polarization transfer — pulsed DNP and chemically equivalent PHIP","authors":"Martin C. Korzeczek ,&nbsp;Laurynas Dagys ,&nbsp;Christoph Müller ,&nbsp;Benedikt Tratzmiller ,&nbsp;Alon Salhov ,&nbsp;Tim Eichhorn ,&nbsp;Jochen Scheuer ,&nbsp;Stephan Knecht ,&nbsp;Martin B. Plenio ,&nbsp;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}

{"title":"Unified understanding of the breakdown of thermal mixing dynamic nuclear polarization: The role of temperature and radical concentration","authors":"Ludovica M. Epasto ,&nbsp;Thibaud Maimbourg ,&nbsp;Alberto Rosso ,&nbsp;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-1-¹³C 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.</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}

{"title":"High-frequency high-power DNP/EPR spectrometer operating at 7 T magnetic field","authors":"Alexander A. Nevzorov,&nbsp;Antonin Marek,&nbsp;Sergey Milikisiyants,&nbsp;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>_1e fields. Three-pulse electron spin echo nutation experiments were employed to characterize the <em>B</em>_1e 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 &lt; 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 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 <em>tri</em>-phenyl phosphine co-dissolved with 100 mM of BDPA in toluene‑<em>d</em>₈.</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}

{"title":"Segmented RF shield design to minimize eddy currents for low-field Halbach MRI systems","authors":"Bart de Vos ,&nbsp;Rob Remis ,&nbsp;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}

{"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,&nbsp;Jonas Lins,&nbsp;Jan Kergassner,&nbsp;Laura Wienands,&nbsp;Sonja Döller,&nbsp;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 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.</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}