Magnetic resonance (Gottingen, Germany)最新文献

{"title":"Automated manufacturing process for sustainable prototyping of nuclear magnetic resonance transceivers.","authors":"Sagar Wadhwa, Nan Wang, Klaus-Martin Reichert, Manuel Butzer, Omar Nassar, Mazin Jouda, Jan G Korvink, Ulrich Gengenbach, Dario Mager, Martin Ungerer","doi":"10.5194/mr-6-199-2025","DOIUrl":"10.5194/mr-6-199-2025","url":null,"abstract":"<p><p>Additive manufacturing has enabled rapid prototyping of components with minimum investment in specific fabrication infrastructure. These tools allow for a fast iteration from design to functional prototypes within days or even hours. Such prototyping technologies exist in many fields, including three-dimensional mechanical components and printed electric circuit boards (PCBs) for electrical connectivity, to mention two. In the case of nuclear magnetic resonance (NMR) spectroscopy, one needs the combination of both fields; we need to fabricate three-dimensional electrically conductive tracks as coils that are wrapped around a sample container. Fabricating such structures is difficult (e.g., six-axis micro-milling) or simply not possible with conventional methods. In this paper, we modified an additive manufacturing method that is based on the extrusion of conductive ink to fast-prototype solenoidal coil designs for NMR. These NMR coils need to be as close to the sample as possible and, by their shape, have specific inductive values. The performance of the designs was first investigated using electromagnetic field simulations and circuit simulations. The coil found to have optimal parameters for NMR was fabricated by extrusion printing, and its performance was tested in a 1.05 <math><mrow><mi>T</mi></mrow> </math> imaging magnet. The objective is to demonstrate reproducible rapid prototyping of complicated designs with high precision that, as a side effect, hardly produces material waste during production.</p>","PeriodicalId":93333,"journal":{"name":"Magnetic resonance (Gottingen, Germany)","volume":"6 2","pages":"199-210"},"PeriodicalIF":0.0,"publicationDate":"2025-07-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12332885/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144818591","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":"Determining large hyperfine interactions of a model flavoprotein in the semiquinone state using pulse EPR (electron paramagnetic resonance) techniques.","authors":"Jesús I Martínez, Susana Frago, Milagros Medina, Inés García-Rubio","doi":"10.5194/mr-6-183-2025","DOIUrl":"10.5194/mr-6-183-2025","url":null,"abstract":"&lt;p&gt;&lt;p&gt;Flavoproteins are a versatile class of proteins involved in numerous biological processes, including redox reactions, electron transfer, and signal transduction, often relying on their ability to stabilize different oxidation states of their flavin cofactor. A critical feature of flavin cofactors is their capacity to achieve, within particular protein environments, a semiquinone state that plays a pivotal role in mediating single-electron transfer events and that is key to understanding flavoprotein reactivity. Hyperfine interactions between the unpaired electron and magnetic nuclei in the isoalloxazine ring provide valuable insights into the semiquinone state and its mechanistic roles. This study investigates the hyperfine interactions of isotopically labeled flavodoxin (Fld) with &lt;math&gt; &lt;mrow&gt;&lt;msup&gt;&lt;mi&gt;&lt;/mi&gt; &lt;mn&gt;13&lt;/mn&gt;&lt;/msup&gt; &lt;mi&gt;C&lt;/mi&gt;&lt;/mrow&gt; &lt;/math&gt; and &lt;math&gt; &lt;mrow&gt;&lt;msup&gt;&lt;mi&gt;&lt;/mi&gt; &lt;mn&gt;15&lt;/mn&gt;&lt;/msup&gt; &lt;mi&gt;N&lt;/mi&gt;&lt;/mrow&gt; &lt;/math&gt; in specific positions of the flavin mononucleotide (FMN) ring using advanced electron paramagnetic resonance (EPR) techniques. The combination of continuous-wave (CW) EPR at the X-band and ELDOR-detected NMR and HYSCORE at the Q-band revealed a strong and anisotropic hyperfine interaction with the nucleus of &lt;math&gt; &lt;mrow&gt;&lt;msup&gt;&lt;mi&gt;&lt;/mi&gt; &lt;mn&gt;13&lt;/mn&gt;&lt;/msup&gt; &lt;mi&gt;C&lt;/mi&gt;&lt;/mrow&gt; &lt;/math&gt; at 4a and yielded principal tensor values of 40, &lt;math&gt;&lt;mrow&gt;&lt;mo&gt;-&lt;/mo&gt; &lt;mn&gt;13.5&lt;/mn&gt;&lt;/mrow&gt; &lt;/math&gt; , and &lt;math&gt;&lt;mrow&gt;&lt;mo&gt;-&lt;/mo&gt; &lt;mn&gt;9&lt;/mn&gt;&lt;/mrow&gt; &lt;/math&gt; MHz, the first of which is associated with the axis perpendicular to the flavin plane. On the other hand, as predicted, the hyperfine interaction with the &lt;math&gt; &lt;mrow&gt;&lt;msup&gt;&lt;mi&gt;&lt;/mi&gt; &lt;mn&gt;13&lt;/mn&gt;&lt;/msup&gt; &lt;mi&gt;C&lt;/mi&gt;&lt;/mrow&gt; &lt;/math&gt; nucleus in position 2 was minimal. Additionally, HYSCORE experiments on &lt;math&gt; &lt;mrow&gt;&lt;msup&gt;&lt;mi&gt;&lt;/mi&gt; &lt;mn&gt;15&lt;/mn&gt;&lt;/msup&gt; &lt;mi&gt;N&lt;/mi&gt;&lt;/mrow&gt; &lt;/math&gt; -FMN-labeled Fld provided precise axial hyperfine parameters, i.e., (74, 5.6, 5.6) &lt;math&gt;&lt;mrow&gt;&lt;mi&gt;MHz&lt;/mi&gt;&lt;/mrow&gt; &lt;/math&gt; for &lt;math&gt; &lt;mrow&gt;&lt;msup&gt;&lt;mi&gt;&lt;/mi&gt; &lt;mn&gt;15&lt;/mn&gt;&lt;/msup&gt; &lt;mi&gt;N&lt;/mi&gt;&lt;/mrow&gt; &lt;/math&gt; (5) and (38, 3.2, 3.2) &lt;math&gt;&lt;mrow&gt;&lt;mi&gt;MHz&lt;/mi&gt;&lt;/mrow&gt; &lt;/math&gt; for &lt;math&gt; &lt;mrow&gt;&lt;msup&gt;&lt;mi&gt;&lt;/mi&gt; &lt;mn&gt;15&lt;/mn&gt;&lt;/msup&gt; &lt;mi&gt;N&lt;/mi&gt;&lt;/mrow&gt; &lt;/math&gt; (10). These were used to refine quadrupole tensor values for &lt;math&gt; &lt;mrow&gt;&lt;msup&gt;&lt;mi&gt;&lt;/mi&gt; &lt;mn&gt;14&lt;/mn&gt;&lt;/msup&gt; &lt;mi&gt;N&lt;/mi&gt;&lt;/mrow&gt; &lt;/math&gt; nuclei through isotope-dependent scaling. These results showcase the potential of combining CW EPR, ELDOR-detected NMR, and HYSCORE with isotopic labeling to probe electronic and nuclear interactions in flavoproteins. The new data complete and refine the existing experimental map for the electronic structure of the flavin cofactor and expose systematic divergences between the calculated and experimental values of hyperfine couplings of the atoms that contribute most to the semi-occupied orbital (SOMO). This could indicate a slight but significant shift in the unpaired electron density from position 4a towards the central nitrogens of the pyrazine ri","PeriodicalId":93333,"journal":{"name":"Magnetic resonance (Gottingen, Germany)","volume":"6 2","pages":"183-197"},"PeriodicalIF":0.0,"publicationDate":"2025-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12326372/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144796350","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":"Coherence locking in a parallel nuclear magnetic resonance probe defends against gradient field spillover.","authors":"Mengjia He, Neil MacKinnon, Dominique Buyens, Burkhard Luy, Jan G Korvink","doi":"10.5194/mr-6-173-2025","DOIUrl":"10.5194/mr-6-173-2025","url":null,"abstract":"<p><p>The implementation of parallel nuclear magnetic resonance detection aims to enhance measurement throughput in support of high-throughput-screening applications, including, for example, drug discovery. In support of modern pulse sequences and solvent suppression methods, each detection site must have independent pulsed field gradient capabilities. Hereby, a challenge is introduced in which the local gradients applied in parallel detectors introduce field spillover into adjacent channels, leading to spin dephasing and, hence, to signal suppression. This study proposes a compensation scheme employing optimized pulses to achieve coherence locking during gradient pulse periods. The design of coherence-locking pulses utilizes optimal control to address gradient-induced field inhomogeneity. These pulses are applied in a pulsed-gradient spin echo (PGSE) experiment and a parallel heteronuclear single quantum coherence (HSQC) experiment, demonstrating their effectiveness in protecting the desired coherences from gradient field spillover. This compensation scheme presents a valuable solution for magnetic resonance probes equipped with parallel and independently switchable gradient coils.</p>","PeriodicalId":93333,"journal":{"name":"Magnetic resonance (Gottingen, Germany)","volume":"6 2","pages":"173-181"},"PeriodicalIF":0.0,"publicationDate":"2025-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12302023/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144736011","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":"Automated wide-line nuclear quadrupole resonance of mixed-cation lead-halide perovskites.","authors":"Jop W Wolffs, Jennifer S Gómez, Gerrit E Janssen, Gilles A de Wijs, Arno P M Kentgens","doi":"10.5194/mr-6-143-2025","DOIUrl":"10.5194/mr-6-143-2025","url":null,"abstract":"<p><p>Nuclear quadrupole resonance (NQR), a technique related to nuclear magnetic resonance, is extremely sensitive to local crystal composition and structure. Unfortunately, in disordered materials, this sensitivity also leads to very large linewidths, presenting a technical challenge and requiring a serious time investment to get a full spectrum. Here, we describe our newly developed, automated NQR set-up to acquire high-quality wide-line spectra. Using this set-up, we carried out ¹²⁷I NQR on three mixed-cation lead-halide perovskites (LHPs) of the form MA _<i>x</i> FA_1-<i>x</i> PbI₃ (where MA denotes methylammonium; FA denotes formamidinium; and <math><mrow><mi>x</mi> <mspace></mspace> <mo>=</mo></mrow> </math> 0.25, 0.50 and 0.75) at various temperatures. We achieve a signal-to-noise ratio of up to <math><mrow><mo>∼</mo> <mspace></mspace> <mn>400</mn></mrow> </math> for lineshapes with a full width at half maximum of <math><mrow><mo>∼</mo> <mspace></mspace> <mn>2.5</mn> <mspace></mspace> <mi>MHz</mi></mrow> </math> acquired with a spectral width of 20 MHz in the course of 2-3 d. The spectra, which at least partially exhibit features encoding structural information, are interpreted using a statistical model. This model finds a degree of MA-MA and FA-FA clustering ( <math><mrow><mn>0.2</mn> <mspace></mspace> <mo>≤</mo> <mspace></mspace> <mi>S</mi> <mspace></mspace> <mo>≤</mo> <mspace></mspace> <mn>0.35</mn></mrow> </math> ). This proof-of-principle for both the wide-line NQR set-up and the statistical model widens the applicability of an underutilised avenue of non-invasive structural research.</p>","PeriodicalId":93333,"journal":{"name":"Magnetic resonance (Gottingen, Germany)","volume":"6 2","pages":"143-155"},"PeriodicalIF":0.0,"publicationDate":"2025-07-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12285786/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144700596","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":"3D-printed microcell for protein NMR at high ionic strengths and small sample volumes.","authors":"Tayeb Kakeshpour, Martin D Gelenter, Jinfa Ying, Ad Bax","doi":"10.5194/mr-6-157-2025","DOIUrl":"10.5194/mr-6-157-2025","url":null,"abstract":"<p><p>Standard solution NMR measurements use 5 mm outer diameter (OD) sample tubes that require ca. 0.5 mL of solvent to minimize \"end effects\" on magnetic field homogeneity in the active volume of the sample. Shigemi cells reduce the solvent requirement to ca. 0.29 mL. At high ionic strength or at ultrahigh magnetic fields, smaller OD samples are needed to study samples in conductive, radiofrequency-absorbing solvents such as water. We demonstrate an effective and inexpensive alternative for reducing the active sample volume to 0.13 mL by 3D printing ellipsoidal shaped cells that are inserted into 5 mm OD NMR tubes. Static magnetic susceptibility, <math><mi>χ</mi></math> , of printer resin was measured using a simple slice-selection pulse sequence. We found that the <math><mi>χ</mi></math> of water increases linearly with NaCl concentration from <math><mrow><mo>-</mo> <mn>9.05</mn></mrow> </math> to <math><mrow><mo>-</mo> <mn>8.65</mn></mrow> </math> ppm for 0 to 2 M NaCl. The <math><mi>χ</mi></math> of D₂O was measured to be <math><mrow><mo>-</mo> <mn>9.01</mn></mrow> </math> ppm. The susceptibility difference between the resin ( <math><mrow><mi>χ</mi> <mo>=</mo> <mo>-</mo> <mn>9.40</mn></mrow> </math> ppm) and water can be minimized by paramagnetic doping of the resin. Such doping was found to be unnecessary for obtaining high-quality protein NMR spectra when using ellipsoidal-shaped cells that are insensitive to susceptibility mismatching. The microcells offer outstanding radiofrequency (RF) and good <math> <mrow><msub><mi>B</mi> <mi>o</mi></msub> </mrow> </math> homogeneities. Integrated 600 MHz heteronuclear single quantum coherence (HSQC) signal intensities for the microcell sample in phosphate-buffered saline (PBS) buffer were <math><mrow><mn>6.5</mn> <mo>±</mo> <mn>4</mn></mrow> </math> % lower than for 0.5 mL of the same protein solution in a regular 5 mm sample tube. The cell is demonstrated for N-acetylated <math><mi>α</mi></math> -synuclein in PBS buffer and for observing tetramerization of melittin at 2 M NaCl.</p>","PeriodicalId":93333,"journal":{"name":"Magnetic resonance (Gottingen, Germany)","volume":"6 2","pages":"157-172"},"PeriodicalIF":0.0,"publicationDate":"2025-07-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12296210/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144736010","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":"Inter-residue through-space scalar ¹⁹F-¹⁹F couplings between CH₂F groups in a protein.","authors":"Yi Jiun Tan, Elwy H Abdelkader, Iresha D Herath, Ansis Maleckis, Gottfried Otting","doi":"10.5194/mr-6-131-2025","DOIUrl":"10.5194/mr-6-131-2025","url":null,"abstract":"&lt;p&gt;&lt;p&gt;Using cell-free protein synthesis, the protein G B1 domain (GB1) was prepared with uniform high-level substitution of leucine by (2 &lt;math&gt;&lt;mi&gt;S&lt;/mi&gt;&lt;/math&gt; ,4 &lt;math&gt;&lt;mi&gt;S&lt;/mi&gt;&lt;/math&gt; )-5-fluoroleucine (FLeu1), (2 &lt;math&gt;&lt;mi&gt;S&lt;/mi&gt;&lt;/math&gt; ,4 &lt;math&gt;&lt;mi&gt;R&lt;/mi&gt;&lt;/math&gt; )-5-fluoroleucine (FLeu2), or 5,5&lt;sup&gt;'&lt;/sup&gt;-difluoroleucine (diFLeu). &lt;math&gt; &lt;mrow&gt;&lt;msup&gt;&lt;mi&gt;&lt;/mi&gt; &lt;mn&gt;19&lt;/mn&gt;&lt;/msup&gt; &lt;mi&gt;F&lt;/mi&gt;&lt;/mrow&gt; &lt;/math&gt; nuclear magnetic resonance (NMR) spectra showed chemical shift ranges spanning more than 9 &lt;math&gt;&lt;mrow&gt;&lt;mi&gt;ppm&lt;/mi&gt;&lt;/mrow&gt; &lt;/math&gt; . Through-space scalar &lt;math&gt; &lt;mrow&gt;&lt;msup&gt;&lt;mi&gt;&lt;/mi&gt; &lt;mn&gt;19&lt;/mn&gt;&lt;/msup&gt; &lt;mi&gt;F&lt;/mi&gt; &lt;msup&gt;&lt;mtext&gt;-&lt;/mtext&gt; &lt;mn&gt;19&lt;/mn&gt;&lt;/msup&gt; &lt;mi&gt;F&lt;/mi&gt;&lt;/mrow&gt; &lt;/math&gt; couplings between &lt;math&gt; &lt;mrow&gt;&lt;msub&gt;&lt;mi&gt;CH&lt;/mi&gt; &lt;mn&gt;2&lt;/mn&gt;&lt;/msub&gt; &lt;mi&gt;F&lt;/mi&gt;&lt;/mrow&gt; &lt;/math&gt; groups arising from transient fluorine-fluorine contacts are readily manifested in [ &lt;math&gt; &lt;mrow&gt;&lt;msup&gt;&lt;mi&gt;&lt;/mi&gt; &lt;mn&gt;19&lt;/mn&gt;&lt;/msup&gt; &lt;mi&gt;F&lt;/mi&gt;&lt;/mrow&gt; &lt;/math&gt; , &lt;math&gt; &lt;mrow&gt;&lt;msup&gt;&lt;mi&gt;&lt;/mi&gt; &lt;mn&gt;19&lt;/mn&gt;&lt;/msup&gt; &lt;mi&gt;F&lt;/mi&gt;&lt;/mrow&gt; &lt;/math&gt; ]-TOCSY spectra. The &lt;math&gt; &lt;mrow&gt;&lt;msup&gt;&lt;mi&gt;&lt;/mi&gt; &lt;mn&gt;19&lt;/mn&gt;&lt;/msup&gt; &lt;mi&gt;F&lt;/mi&gt;&lt;/mrow&gt; &lt;/math&gt; chemical shifts correlate with the three-bond &lt;math&gt; &lt;mrow&gt;&lt;msup&gt;&lt;mi&gt;&lt;/mi&gt; &lt;mn&gt;1&lt;/mn&gt;&lt;/msup&gt; &lt;mi&gt;H&lt;/mi&gt;&lt;/mrow&gt; &lt;/math&gt; - &lt;math&gt; &lt;mrow&gt;&lt;msup&gt;&lt;mi&gt;&lt;/mi&gt; &lt;mn&gt;19&lt;/mn&gt;&lt;/msup&gt; &lt;mi&gt;F&lt;/mi&gt;&lt;/mrow&gt; &lt;/math&gt; couplings ( &lt;math&gt; &lt;mrow&gt;&lt;msup&gt;&lt;mi&gt;&lt;/mi&gt; &lt;mn&gt;3&lt;/mn&gt;&lt;/msup&gt; &lt;msub&gt;&lt;mi&gt;J&lt;/mi&gt; &lt;mi&gt;HF&lt;/mi&gt;&lt;/msub&gt; &lt;/mrow&gt; &lt;/math&gt; ), confirming the &lt;math&gt;&lt;mi&gt;γ&lt;/mi&gt;&lt;/math&gt; -gauche effect as the predominant determinant of the &lt;math&gt; &lt;mrow&gt;&lt;msup&gt;&lt;mi&gt;&lt;/mi&gt; &lt;mn&gt;19&lt;/mn&gt;&lt;/msup&gt; &lt;mi&gt;F&lt;/mi&gt;&lt;/mrow&gt; &lt;/math&gt; chemical shifts of the &lt;math&gt; &lt;mrow&gt;&lt;msub&gt;&lt;mi&gt;CH&lt;/mi&gt; &lt;mn&gt;2&lt;/mn&gt;&lt;/msub&gt; &lt;mi&gt;F&lt;/mi&gt;&lt;/mrow&gt; &lt;/math&gt; groups. Different &lt;math&gt; &lt;mrow&gt;&lt;msup&gt;&lt;mi&gt;&lt;/mi&gt; &lt;mn&gt;3&lt;/mn&gt;&lt;/msup&gt; &lt;msub&gt;&lt;mi&gt;J&lt;/mi&gt; &lt;mi&gt;HF&lt;/mi&gt;&lt;/msub&gt; &lt;/mrow&gt; &lt;/math&gt; couplings of different &lt;math&gt; &lt;mrow&gt;&lt;msub&gt;&lt;mi&gt;CH&lt;/mi&gt; &lt;mn&gt;2&lt;/mn&gt;&lt;/msub&gt; &lt;mi&gt;F&lt;/mi&gt;&lt;/mrow&gt; &lt;/math&gt; groups indicate that the rotation of the &lt;math&gt; &lt;mrow&gt;&lt;msub&gt;&lt;mi&gt;CH&lt;/mi&gt; &lt;mn&gt;2&lt;/mn&gt;&lt;/msub&gt; &lt;mi&gt;F&lt;/mi&gt;&lt;/mrow&gt; &lt;/math&gt; groups can be sufficiently restricted in different protein environments to result in the preferential population of a single rotamer. The &lt;math&gt; &lt;mrow&gt;&lt;msup&gt;&lt;mi&gt;&lt;/mi&gt; &lt;mn&gt;3&lt;/mn&gt;&lt;/msup&gt; &lt;msub&gt;&lt;mi&gt;J&lt;/mi&gt; &lt;mi&gt;HF&lt;/mi&gt;&lt;/msub&gt; &lt;/mrow&gt; &lt;/math&gt; couplings also show that &lt;math&gt; &lt;mrow&gt;&lt;msub&gt;&lt;mi&gt;CH&lt;/mi&gt; &lt;mn&gt;2&lt;/mn&gt;&lt;/msub&gt; &lt;mi&gt;F&lt;/mi&gt;&lt;/mrow&gt; &lt;/math&gt; groups populate the different rotameric states differently in the 5,5&lt;sup&gt;'&lt;/sup&gt;-difluoroleucine residues than in the monofluoroleucine analogues, showing that two &lt;math&gt; &lt;mrow&gt;&lt;msub&gt;&lt;mi&gt;CH&lt;/mi&gt; &lt;mn&gt;2&lt;/mn&gt;&lt;/msub&gt; &lt;mi&gt;F&lt;/mi&gt;&lt;/mrow&gt; &lt;/math&gt; groups in close proximity influence each other's conformation. Nonetheless, the &lt;math&gt; &lt;mrow&gt;&lt;msup&gt;&lt;mi&gt;&lt;/mi&gt; &lt;mn&gt;19&lt;/mn&gt;&lt;/msup&gt; &lt;mi&gt;F&lt;/mi&gt;&lt;/mrow&gt; &lt;/math&gt; resonances of the &lt;math&gt; &lt;mrow&gt;&lt;msup&gt;&lt;mi&gt;C&lt;/mi&gt; &lt;mrow&gt;&lt;mi&gt;δ&lt;/mi&gt; &lt;mn&gt;1&lt;/mn&gt;&lt;/mrow&gt; &lt;/msup&gt; &lt;msub&gt;&lt;mi&gt;H&lt;/mi&gt; &lt;mn&gt;2&lt;/mn&gt;&lt;/msub&gt; &lt;mi&gt;F&lt;/mi&gt;&lt;/mrow&gt; &lt;/math&gt; and &lt;math&gt; &lt;mrow&gt;&lt;msup&gt;&lt;mi&gt;C&lt;/mi&gt; &lt;mrow&gt;&lt;mi&gt;δ&lt;/mi&gt; &lt;mn&gt;2&lt;/mn&gt;&lt;/mrow&gt; &lt;/msup&gt; &lt;msub&gt;&lt;mi&gt;H&lt;/mi&gt;","PeriodicalId":93333,"journal":{"name":"Magnetic resonance (Gottingen, Germany)","volume":"6 2","pages":"131-142"},"PeriodicalIF":0.0,"publicationDate":"2025-07-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12281167/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144700597","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":"Pseudo rotary resonance relaxation dispersion effects in isotropic samples.","authors":"Evgeny Nimerovsky, Jonas Mehrens, Loren B Andreas","doi":"10.5194/mr-6-119-2025","DOIUrl":"10.5194/mr-6-119-2025","url":null,"abstract":"<p><p>Enhanced transverse relaxation near rotary resonance conditions is a well-documented effect for anisotropic solid samples undergoing magic-angle spinning (MAS). We report transverse signal decay associated with rotary resonance conditions for rotating liquids, a surprising observation, since first-order anisotropic interactions are averaged at a much faster timescale compared with the spinning frequency. We report measurements of <math> <mrow><msup><mi></mi> <mn>13</mn></msup> <mi>C</mi></mrow> </math> and <math> <mrow><msup><mi></mi> <mn>1</mn></msup> <mi>H</mi></mrow> </math> signal intensities under spin lock for spinning samples of polybutadiene rubber, polyethylene glycol solution, and 99.96 % <math> <mrow><msub><mi>D</mi> <mn>2</mn></msub> <mi>O</mi></mrow> </math> . A drastic reduction in spin-lock signal intensities is observed when the spin-lock frequency matches 1 or 2 times the MAS rate. In addition, oscillations of the signal are observed, consistent with a coherent origin of the effect, a pseudo rotary resonance relaxation dispersion (pseudo-RRD). Through simulations, we qualitatively describe the appearance of pseudo-RRD, which can be explained by time dependence caused by sample rotation and an inhomogeneous field, the origin of which is an instrumental imperfection. Consideration of this effect is important for MAS experiments based on rotary resonance conditions and motivates the design of new MAS coils with improved radio frequency (RF)-field homogeneity.</p>","PeriodicalId":93333,"journal":{"name":"Magnetic resonance (Gottingen, Germany)","volume":"6 1","pages":"119-129"},"PeriodicalIF":0.0,"publicationDate":"2025-06-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12247080/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144628062","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":"ih-RIDME: a pulse EPR experiment to probe the heterogeneous nuclear environment.","authors":"Sergei Kuzin, Victoriya N Syryamina, Mian Qi, Moritz Fischer, Miriam Hülsmann, Adelheid Godt, Gunnar Jeschke, Maxim Yulikov","doi":"10.5194/mr-6-93-2025","DOIUrl":"10.5194/mr-6-93-2025","url":null,"abstract":"<p><p>The intermolecular hyperfine relaxation-induced dipolar modulation enhancement experiment (ih-RIDME) is a pulse electron paramagnetic resonance (EPR) experiment that can be used to probe the properties of a nuclear spin bath in the vicinity of an unpaired electron. The underlying mechanism is the hyperfine spectral diffusion of the electron spin during the mixing block. A quantitative description of the diffusion kinetics being applied to establish the ih-RIDME data model allows one to extend this method to systems with heterogeneous nuclear arrangements assuming a distribution of the local nuclear densities. The heterogeneity can stem from the solvent or the intrinsic nuclei of a structurally flexible (macro)molecule. Therefore, the fitted distribution function can further serve as a method for heterogeneity characterization, quantification and structure-based analysis. Here, we present a detailed introduction to the principles of ih-RIDME application to heterogeneous systems. We discuss the spectral resolution, determination of the spectral diffusion parameters and influence of noise in the experimental data. We further demonstrate the application of the ih-RIDME method to a model spin-labelled macromolecule with unstructured domains. The fitted distribution of local proton densities was reproduced with the help of a conformational ensemble generated using the Monte Carlo approach. Finally, we discuss several pulse sequences exploiting the HYperfine Spectral Diffusion Echo MOdulatioN (HYSDEMON) effect with an improved signal-to-noise ratio.</p>","PeriodicalId":93333,"journal":{"name":"Magnetic resonance (Gottingen, Germany)","volume":"6 1","pages":"93-112"},"PeriodicalIF":0.0,"publicationDate":"2025-03-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12247092/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144628060","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":"Analytical expressions for the time evolution of spin systems affected by two or more interactions.","authors":"Günter Hempel","doi":"10.5194/mr-6-77-2025","DOIUrl":"10.5194/mr-6-77-2025","url":null,"abstract":"<p><p>Analytical expressions for the description of the time evolution of spin systems beyond product-operator formalism (POF) can be obtained if a low-dimensional subspace of the Liouville space has been found in which the time evolution of the spin system takes place completely. This can be achieved using a procedure that consists of repeated application of the commutator of the Hamiltonian with the density operator. This iteration continues as long as the result of such a commutator operation contains a term that is linearly independent of all the operators appearing in the previous commutator operations. The coefficients of the resulting system of commutator relations can be immediately inserted into the generic propagation formulae given in this article if the system contains two, three, or four equations. In cases where the validity conditions of any of these propagation formulae are not met, the coefficients are used as intermediate steps to obtain both the Liouvillian and propagator matrices of the system. Several application examples are given where an analytical equation can be obtained for the description of the time evolution of small spin systems under the influence of two or more interactions. This procedure for finding the Liouvillian matrix is not limited to time-independent interactions. Some examples illustrate the treatment of time-dependent problems using this method.</p>","PeriodicalId":93333,"journal":{"name":"Magnetic resonance (Gottingen, Germany)","volume":"6 1","pages":"77-92"},"PeriodicalIF":0.0,"publicationDate":"2025-02-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12247082/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144628058","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":"Increased sensitivity in electron-nuclear double resonance spectroscopy with chirped radiofrequency pulses.","authors":"Julian Stropp, Nino Wili, Niels C Nielsen, Daniel Klose","doi":"10.5194/mr-6-33-2025","DOIUrl":"10.5194/mr-6-33-2025","url":null,"abstract":"<p><p>Electron-nuclear double resonance (ENDOR) spectroscopy is an EPR technique to detect the nuclear frequency spectra of hyperfine coupled nuclei close to paramagnetic centers, which have interactions that are not resolved in continuous wave EPR spectra and may be fast relaxing on the timescale of NMR. For the common case of non-crystalline solids, such as powders or frozen solutions of transition metal complexes, the anisotropy of the hyperfine and nuclear quadrupole interactions renders ENDOR lines often several megahertz (MHz) broad, thus diminishing intensity. With commonly used ENDOR pulse sequences, only a small fraction of the NMR/ENDOR line is excited with a typical radiofrequency (RF) pulse length of several tens of microseconds ( <math><mrow><mi>µ</mi></mrow> </math> s), and this limits the sensitivity in conventional ENDOR experiments. In this work, we show the benefit of chirped RF excitation in frequency-domain ENDOR as a simple yet effective way to significantly improve sensitivity. We demonstrate on a frozen solution of Cu(II)-tetraphenylporphyrin that the intensity of broad copper and nitrogen ENDOR lines increases up to 9-fold compared to single-frequency RF excitation, thus making the detection of metal ENDOR spectra more feasible. The tunable bandwidth of the chirp RF pulses allows the operator to optimize for sensitivity and choose a tradeoff with resolution, opening up options previously inaccessible in ENDOR spectroscopy. Also, chirp pulses help to reduce RF amplifier overtones, since lower RF powers suffice to achieve intensities matching conventional ENDOR. In 2D triple resonance experiments (TRIPLE), the signal increase exceeds 10 times for some lines, thus making chirped 2D TRIPLE experiments feasible even for broad peaks in manageable acquisition times.</p>","PeriodicalId":93333,"journal":{"name":"Magnetic resonance (Gottingen, Germany)","volume":"6 1","pages":"33-42"},"PeriodicalIF":0.0,"publicationDate":"2025-01-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12247087/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144628061","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}