Journal of Magnetic Resonance Open最新文献

{"title":"New challenges and opportunities for low-field MRI","authors":"Esteban Anoardo ,&nbsp;Gonzalo G. Rodriguez","doi":"10.1016/j.jmro.2022.100086","DOIUrl":"https://doi.org/10.1016/j.jmro.2022.100086","url":null,"abstract":"<div><p>In this manuscript we deal with recent advances in low-field Magnetic Resonance Imaging (MRI). The development of low-cost MRI solutions allowing portability and trustable diagnosis is a hot topic worldwide by these days. We analyze basic technical issues of recent examples of fixed-field instruments operating at low-field. Then we discuss pros and cons of the pre-polarized approach, from both physical and technical perspectives. Permanent magnet and electromagnet technology are confronted. Finally, magnetic field-cycling is introduced as an alternative MRI technique, where field-dependent experiments can be exploded for the development of new contrast mechanisms that are not feasible for fixed-field MRI instruments. As field cycled machines usually deals with switched currents in electromagnets, magnetic field instability and inhomogeneity are the main limiting factors affecting image quality. We finalize this manuscript discussing how it turns possible to overcome these limitations, thus opening new possibilities for the development of cost effective MRI technology.</p></div>","PeriodicalId":365,"journal":{"name":"Journal of Magnetic Resonance Open","volume":"14 ","pages":"Article 100086"},"PeriodicalIF":2.624,"publicationDate":"2023-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"1826371","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Solid state NMR characterization of NaNbO3 and LiNbO3 nanoparticles obtained by microwave-assisted combustion","authors":"Guilherme O. Siqueira ,&nbsp;Geraldo M. de Lima ,&nbsp;Francielle C. Araújo ,&nbsp;Fabrício V. de Andrade ,&nbsp;Tiago B. Moraes ,&nbsp;Marcos de Oliveira Jr.","doi":"10.1016/j.jmro.2022.100088","DOIUrl":"https://doi.org/10.1016/j.jmro.2022.100088","url":null,"abstract":"<div><p>Nanoparticles of LiNbO₃ and NaNbO₃ were obtained for the first time by microwave-assisted combustion. Preliminary experiments reveal that the synthetic conditions influence their microstructure and optoelectronic features. Therefore, there is a need for performing the structural characterization of these materials, obtained by this new route. In the case of NaNbO₃, there are two polimorphs which are stable at room temperature, space groups P2₁ma and Pbma. Powder x-Ray diffraction experiments were not capable to identify the crystalline phases present in the nanoparticles. Therefore, we have performed a detailed structural characterization of the nanoparticles by 1D and 2D solid state ²³Na and ⁹³Nb Nuclear Magnetic Resonance (NMR) techniques. ²³Na results reveal the presence of both phases, Pbma and P2₁ma, for samples prepared using NaNO₃ precursor in a 1:1 Na:Nb ratio or NaCl in excess. On the other hand, the P2₁ma polymorph could be isolated in the synthesis using NaCl salt in 1:1 Na:Nb ratio. On the other hand, LiNbO₃ nanoparticles display the usual rhombohedral structure R3c. ⁷Li MAS NMR results reveal the presence of two types of Li species, with distinct dynamics. Highly mobile Li⁺ ions are found at the surface of the nanoparticles, while bulk Li⁺ show restricted movement. Finally, as a proof of principle, the photocatalytic activity of these niobates was tested for the degradation of methylene blue dye, a common organic-water contaminant.</p></div>","PeriodicalId":365,"journal":{"name":"Journal of Magnetic Resonance Open","volume":"14 ","pages":"Article 100088"},"PeriodicalIF":2.624,"publicationDate":"2023-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"1826373","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Pulse sequence induced variability combined with multivariate analysis as a potential tool for 13C solid-state NMR signals separation, quantification, and classification","authors":"Etelvino H. Novotny ,&nbsp;Rodrigo H.S. Garcia ,&nbsp;Eduardo R. deAzevedo","doi":"10.1016/j.jmro.2022.100089","DOIUrl":"https://doi.org/10.1016/j.jmro.2022.100089","url":null,"abstract":"<div><p>Multivariate Curve Resolution (MCR) is a multivariate analysis procedure commonly used to analyze spectroscopic data providing the number of components coexisting in a chemical system, the pure spectra of the components as well as their concentration profiles. Usually, this procedure relies on the existence of distinct systematic variability among spectra of the different samples, which is provided by different sources of variation associated to differences in samples origin, composition, physical chemical treatment, etc. In solid-state NMR, MCR has been also used as a post-processing method for spectral denoising or editing based on a given NMR property. In this type of use, the variability is induced by the incrementation of a given parameter in the pulse-sequence, which encodes the separation property in the acquired spectra. In this article we further explore the idea of using a specific pulse sequence to induce a controlled variability in the ¹³C solid-state NMR spectra and then apply MCR to separate the pure spectra of the components according to the properties associated to the induced variability. We build upon a previous study of sugarcane bagasse where a series of ¹³C solid-state NMR spectra acquired with the Torchia-<em>T</em>₁ CPMAS pulse sequence, with varying relaxation periods, was combined with different sample treatments, to estimate individual ¹³C solid-state NMR spectra of different molecular components (cellulose, xylan and lignin). Using the same pulse sequence, we show other application examples to demonstrate the potentiality, parameter optimization and/or establish the limitations of the procedure. As a first proof of principle, we apply the approach to commercial semicrystalline medium density polyethylene (MDPE) and polyether ether ketone (PEEK) providing the estimation of the individual ¹³C ssNMR spectra of the polymer chains in the amorphous (short <span><math><msub><mi>T</mi><mn>1</mn></msub></math></span>) and crystalline (long <span><math><msub><mi>T</mi><mn>1</mn></msub></math></span>) domains. The analysis also provided the relative intensities of each estimated pure spectra, which are related to the characteristic <span><math><msub><mi>T</mi><mn>1</mn></msub></math></span> decays of the amorphous and crystalline domain fractions. We also apply the analysis to isotactic poly (1-butene) (iPB-I) as an example in which the induced <span><math><msub><mi>T</mi><mn>1</mn></msub></math></span> variability occurs due to the mobility difference between the polymer backbone and side-chains. A jack-knifing procedure and a student t text allow us to stablish the minimum number of spectra and the range of relaxation periods that need to be used to achieve a precise estimation of the individual pure spectra and their relative intensities. A detail discussion about possible drawbacks, applications to more complex systems, and potential extensions to other type of ind","PeriodicalId":365,"journal":{"name":"Journal of Magnetic Resonance Open","volume":"14 ","pages":"Article 100089"},"PeriodicalIF":2.624,"publicationDate":"2023-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"1826374","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Observation of Li+ jumps in solid inorganic electrolytes over a broad dynamical range: A case study of the lithium phosphidosilicates Li8SiP4 and Li14SiP6","authors":"Björn Wankmiller ,&nbsp;Michael Ryan Hansen","doi":"10.1016/j.jmro.2023.100098","DOIUrl":"https://doi.org/10.1016/j.jmro.2023.100098","url":null,"abstract":"<div><p>⁷Li NMR spectroscopy is known to be very sensitive to translational motion in solids and therefore highly suited for investigating temperature-dependent Li⁺ dynamics. A number of different NMR methods are available for choosing the dynamical range of the observed Li⁺ jump frequencies present in inorganic solid-state electrolytes. This includes ⁷Li spin-alignment echo NMR spectroscopy, static ⁷Li lineshape analysis, and ⁷Li spin-lattice relaxometry that can be used to detect Li⁺ jumps in the Hz, kHz, and MHz range, respectively. We introduce and discuss these NMR techniques with respect to their theoretical description and practical application to investigate the Li⁺ dynamics at different time scales for the two solid-state electrolytes Li₈SiP₄ and Li₁₄SiP₆. The data evaluation for all methods is discussed in detail, focusing on the determination of Li⁺ jump frequencies and activation energies for the investigated self-diffusion processes in a given structure.</p></div>","PeriodicalId":365,"journal":{"name":"Journal of Magnetic Resonance Open","volume":"14 ","pages":"Article 100098"},"PeriodicalIF":2.624,"publicationDate":"2023-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"1826377","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Nuclear pair electron spin echo envelope modulation","authors":"G. Jeschke","doi":"10.1016/j.jmro.2023.100094","DOIUrl":"https://doi.org/10.1016/j.jmro.2023.100094","url":null,"abstract":"<div><p>The interaction of electron spins with homonuclear spin pairs in their vicinity is one of the dominating mechanisms of electron spin echo decay at low temperature and low concentration. Here, we study this mechanism using established concepts of electron spin echo envelope modulation (ESEEM). We obtain analytical expressions for the Hahn echo, the refocused echo, the stimulated echo, and Carr–Purcell pulse trains with small numbers of <span><math><mi>π</mi></math></span> pulses. Hahn echo decay is well approximated by the product of nuclear pair ESEEM functions. The same approximation can explain dependence of stimulated echo decay on the first interpulse delay and provides reasonable time scale estimates for decay of Carr–Purcell echos after an odd number of <span><math><mi>π</mi></math></span> pulses. Carr–Purcell echoes after an even number of <span><math><mi>π</mi></math></span> pulses are rather sensitive to correlations within larger nuclear spin clusters. Approximations improve for both odd and even numbers of <span><math><mi>π</mi></math></span> pulses by factorising the nuclear spin bath into disjoint clusters, provided that modulation due to pairs of spins belonging to different clusters is considered in addition to cluster modulation. The analytical ESEEM expressions for the Hahn echo and the Carr–Purcell echo after two <span><math><mi>π</mi></math></span> pulses have the same mathematical form as the filter functions of these sequences of spin noise spectroscopy. This coincidence provides a computationally very efficient way of predicting Hahn echo decay induced by homonuclear spin pairs. The analytical pair product approximation predicts the previously observed (Bahrenberg et al., 2021) increase of the refocused echo amplitude when one refocusing time is incremented and other one is fixed but longer. In contrast, the spin-noise concept fails to predict this effect.</p></div>","PeriodicalId":365,"journal":{"name":"Journal of Magnetic Resonance Open","volume":"14 ","pages":"Article 100094"},"PeriodicalIF":2.624,"publicationDate":"2023-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"3135446","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Combined experimental and computational 1H NMR study of water adsorption onto graphenic materials","authors":"Alan R. Ambrozio ,&nbsp;Thierry R. Lopes ,&nbsp;Daniel F. Cipriano ,&nbsp;Fábio A.L. de Souza ,&nbsp;Wanderlã L. Scopel ,&nbsp;Jair C.C. Freitas","doi":"10.1016/j.jmro.2022.100091","DOIUrl":"https://doi.org/10.1016/j.jmro.2022.100091","url":null,"abstract":"<div><p>The effects caused by the interaction with graphene-like layers on the <span><math><msup><mrow></mrow><mrow><mn>1</mn></mrow></msup></math></span>H NMR spectra of water molecules adsorbed onto porous carbon materials were investigated by a combination of shielding calculations using density functional theory (DFT) and <span><math><msup><mrow></mrow><mrow><mn>1</mn></mrow></msup></math></span>H NMR experiments. Experimental <span><math><msup><mrow></mrow><mrow><mn>1</mn></mrow></msup></math></span>H NMR spectra were recorded for different water-containing carbon materials (activated carbons and milled graphite samples); the <span><math><msup><mrow></mrow><mrow><mn>1</mn></mrow></msup></math></span>H NMR signals due to adsorbed water in these materials showed a strong shielding effect caused by the electron currents present in the graphene-like layers. This effect was enhanced for activated carbons prepared at high heat treatment temperatures and for milled graphite samples with short milling times, evidencing that the structural organization of the graphene-like layers was the key feature defining the magnitude of the shielding on the <span><math><msup><mrow></mrow><mrow><mn>1</mn></mrow></msup></math></span>H nuclei in the water molecules adsorbed by the analyzed materials. The DFT calculations of the shielding sensed by these <span><math><msup><mrow></mrow><mrow><mn>1</mn></mrow></msup></math></span>H nuclei showed an increased interaction with the graphitic layers as the distance between these layers (representing the pore size) was reduced. A continuous decrease of the <span><math><msup><mrow></mrow><mrow><mn>1</mn></mrow></msup></math></span>H NMR chemical shift was then predicted for pores of smaller sizes, in good agreement with the experimental findings. These calculations also showed a large dispersion of chemical shifts for the several <span><math><msup><mrow></mrow><mrow><mn>1</mn></mrow></msup></math></span>H nuclei in the water clusters, attributed to intermolecular interactions and to shielding variations within the pores. This dispersion, combined with the effects due to the locally anisotropic diamagnetic susceptibility of graphite-like crystallites, are the main contributions to the broadening of the <span><math><msup><mrow></mrow><mrow><mn>1</mn></mrow></msup></math></span>H NMR signals associated with water adsorbed onto porous carbon materials.</p></div>","PeriodicalId":365,"journal":{"name":"Journal of Magnetic Resonance Open","volume":"14 ","pages":"Article 100091"},"PeriodicalIF":2.624,"publicationDate":"2023-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"3451240","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Utility of methyl side chain probes for solution NMR studies of large proteins","authors":"Andrew C. McShan","doi":"10.1016/j.jmro.2022.100087","DOIUrl":"https://doi.org/10.1016/j.jmro.2022.100087","url":null,"abstract":"<div><p>Selective isotopic labeling of methyl side chain groups in proteins and other biomolecules, combined with advances in perdeuteration, new pulse sequences, and high field spectrometers with cryogenic probes, has revolutionized the field of solution nuclear magnetic resonance (NMR) spectroscopy by enabling characterization of macromolecular systems with molecular weights above 1 MDa in their native aqueous environment. This tutorial provides a basic overview for how modern NMR spectroscopists can utilize methyl side chain probes to study their system of interest. The advantages and limitations of methyl side chain probes are discussed. In addition, the preparation of selectively ¹³C-methyl labeled recombinant protein samples, strategies for manual and automated methyl NMR resonance assignment, and the application of methyl probes for characterization of dynamics and conformational exchange are discussed. A sneak preview for ways in which methyl probes are expected to continue to advance the field of biomolecular NMR towards new horizons in solution studies of large supramolecular complexes is also presented.</p></div>","PeriodicalId":365,"journal":{"name":"Journal of Magnetic Resonance Open","volume":"14 ","pages":"Article 100087"},"PeriodicalIF":2.624,"publicationDate":"2023-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"1826372","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Evaluation of multi-channel phase reconstruction methods for quantitative susceptibility mapping on postmortem human brain","authors":"Fábio Seiji Otsuka ,&nbsp;Maria Concepcion Garcia Otaduy ,&nbsp;José Henrique Monteiro Azevedo ,&nbsp;Khallil Taverna Chaim ,&nbsp;Carlos Ernesto Garrido Salmon","doi":"10.1016/j.jmro.2023.100097","DOIUrl":"https://doi.org/10.1016/j.jmro.2023.100097","url":null,"abstract":"<div><p>Quantitative Susceptibility Mapping (QSM) is an established Magnetic Resonance Imaging (MRI) technique with high potential in brain iron studies associated to several neurodegenerative diseases. Unlike other MRI techniques, QSM relies on phase images to estimate tissue's relative susceptibility, therefore requiring a reliable phase data. Phase images from a multi-channel acquisition should be reconstructed in a proper way. On this work it was compared the performance of combination of phase matching algorithms (MCPC3D-S and VRC) and phase combination methods based on a complex weighted sum of phases, considering the magnitude at different powers (<em>k</em> = 0 to 4) as the weighting factor. These reconstruction methods were applied in two datasets: a simulated brain dataset for a 4-coil array and data of 22 postmortem subjects acquired at a 7T scanner using a 32 channels coil. For the simulated dataset, differences between the ground truth and the Root Mean Squared Error (RMSE) were evaluated. For both simulated and postmortem data, the mean (MS) and standard deviation (SD) of susceptibility values of five deep gray matter regions were calculated. For the postmortem subjects, MS and SD were statistically compared across all subjects. A qualitative analysis indicated no differences between methods, except for the Adaptive approach on postmortem data, which showed intense artifacts. In the 20% noise level case, the simulated data showed increased noise in central regions. Quantitative analysis showed that both MS and SD were not statistically different when comparing <span><math><mrow><mi>k</mi><mo>=</mo><mn>1</mn></mrow></math></span> and <span><math><mrow><mi>k</mi><mo>=</mo><mn>2</mn></mrow></math></span> on postmortem brain images, however visual inspection showed some boundaries artifacts on <span><math><mrow><mi>k</mi><mo>=</mo><mn>2</mn></mrow></math></span>. Furthermore, the RMSE decreased (on regions near the coils) and increased (on central regions and on overall QSM) with increasing <span><math><mi>k</mi></math></span>. In conclusion, for reconstruction of phase images from multiple coils with no reference available, alternative methods are needed. In this study it was found that overall, the phase combination with <span><math><mrow><mi>k</mi><mo>=</mo><mn>1</mn></mrow></math></span> is preferred over other powers of <span><math><mi>k</mi></math></span>.</p></div>","PeriodicalId":365,"journal":{"name":"Journal of Magnetic Resonance Open","volume":"14 ","pages":"Article 100097"},"PeriodicalIF":2.624,"publicationDate":"2023-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10062192/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"1826380","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}

{"title":"Conformational dynamics and kinetics of protein interactions by nuclear magnetic resonance","authors":"Adolfo H. Moraes ,&nbsp;Ana Paula Valente","doi":"10.1016/j.jmro.2023.100093","DOIUrl":"https://doi.org/10.1016/j.jmro.2023.100093","url":null,"abstract":"<div><p>Structural information of protein complexes is fundamental for the rational drug design and improvement of vaccines and biosensors. Also, protein misassembly can have severe biological consequences. Here we discuss the challenges of studying protein complexes and show examples of systems characterized using NMR.</p></div>","PeriodicalId":365,"journal":{"name":"Journal of Magnetic Resonance Open","volume":"14 ","pages":"Article 100093"},"PeriodicalIF":2.624,"publicationDate":"2023-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"1826376","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Conducting a three-pulse DEER experiment without dead time: A review","authors":"Sergei A. Dzuba","doi":"10.1016/j.jmro.2023.100100","DOIUrl":"https://doi.org/10.1016/j.jmro.2023.100100","url":null,"abstract":"<div><p>Double electron-electron resonance spectroscopy (DEER, also known as PELDOR) is used to study spin-spin dipolar interactions between spin labels, at the nanoscale range of distances. The DEER effect is obtained as a signal generated by echo-forming microwave (mw) pulses with an additional mw pump pulse applied at a different frequency. It is important to carry out measurements without artefacts induced by overlap of the pulses in the time scale. Such an experiment without the dead-time effect is achieved using the 4-pulse (4p) DEER method. The analysis of the literature performed here shows however that the 3-pulse (3p) DEER can also be free of the dead time problem, for which there are two possibilities. The first occurs using a specially designed bimodal resonator, for which the two frequencies are completely decoupled. The second possibility, which can be implemented for any commercial spectrometer, involves the signal correction based on an additional “blank” measurement with the pump pulse applied outside the EPR resonance. A detailed comparison of the 3p and 4p DEER data obtained previously by Milov et al. [Appl. Magn. Reson. 41 (2011) 59–67] shows that 3p and 4p approaches give similar results. The advantages of the 3p DEER techniques are discussed.</p></div>","PeriodicalId":365,"journal":{"name":"Journal of Magnetic Resonance Open","volume":"14 ","pages":"Article 100100"},"PeriodicalIF":2.624,"publicationDate":"2023-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"1826378","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}