Magnetic resonance (Gottingen, Germany)最新文献

{"title":"Line-narrowing by polychromatic selective spin-locking in NMR.","authors":"Coline Wiame, Hadi Loutfi, Kirill Sheberstov, Geoffrey Bodenhausen","doi":"10.5194/mr-7-135-2026","DOIUrl":"10.5194/mr-7-135-2026","url":null,"abstract":"<p><p>Selective Spin-Locking (SSL) of the magnetisation vectors of selected singlets or multiplets in high-resolution Nuclear Magnetic Resonance (NMR) spectra by mono- or polychromatic selective radio-frequency (RF) irradiation can reduce the line-widths to the limit given by homogeneous <math> <mrow><msub><mi>T</mi> <mrow><mn>1</mn> <mi>ρ</mi></mrow> </msub> </mrow> </math> relaxation. The resulting line-narrowing leads to an increase in signal height of spectra of ¹H, ¹⁹F, ³¹P or other nuclei that is in principle only limited by the ratio <math> <mrow><msub><mi>T</mi> <mrow><mn>1</mn> <mi>ρ</mi></mrow> </msub> </mrow> </math> / <math> <mrow><msub><mi>T</mi> <mn>2</mn></msub> </mrow> </math> *. At the same time, the scalar interactions that give rise to multiplets are decoupled, thus leading to an additional gain in signal height. The amplification factors allow one to use samples at low concentrations. Common one-dimensional (1D) experiments such as inversion recovery (IR) as well as the excitation and reconversion of Long-Lived States (LLS) by Spin-Lock Induced Crossing (SLIC) can significantly benefit from SSL.</p>","PeriodicalId":93333,"journal":{"name":"Magnetic resonance (Gottingen, Germany)","volume":"7 2","pages":"135-145"},"PeriodicalIF":0.0,"publicationDate":"2026-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13641085/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149119835","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":"Simulating the extraction of signal parameters and spectrograms for non-stationary NMR signals.","authors":"Jixin Chen","doi":"10.5194/mr-7-125-2026","DOIUrl":"10.5194/mr-7-125-2026","url":null,"abstract":"<p><p>Free induction decay (FID) signals in nuclear magnetic resonance (NMR) spectroscopy are commonly analyzed using the fast Fourier transform (FFT). This simulation study evaluates complementary methods for short or non-stationary FID signals in which linewidth, dephasing, or decay behavior changes during acquisition. Simulated FIDs containing exponentially damped sinusoids, Gaussian-distributed frequencies, and time-dependent broadening were analyzed using FFT, short-time Fourier transform (STFT), wavelet transform, and direct nonlinear time-domain fitting. Simulations of finite collection windows show that point-sampled FIDs can approximate window-integrated signals after amplitude and phase correction when the collection window is sufficiently sharp and reproducible. FFT remains the fastest and most reliable approach for stationary, sufficiently long, high-signal-to-noise signals. Zero filling improves spectral interpolation but does not recover frequency resolution lost through short acquisition. STFT and wavelet methods reveal time-dependent frequency and decay behavior, although with reduced frequency resolution. Direct time-domain fitting can estimate amplitudes, frequencies, phases, and decay constants from very short, relatively simple FID segments, but its reliability depends on model selection, initial estimates, the number of signal components, and avoidance of local minima. These methods therefore serve complementary roles in analyzing stationary and non-stationary NMR signals.</p>","PeriodicalId":93333,"journal":{"name":"Magnetic resonance (Gottingen, Germany)","volume":"7 2","pages":"125-134"},"PeriodicalIF":0.0,"publicationDate":"2026-09-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13576740/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148978932","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":"Optimally controlled nuclear magnetic resonance (NMR) in electrochemistry: Larmor versus nutation frequency selective spin excitation for locally selective NMR experiments.","authors":"Johannes F Kochs, Armin J Römer, Michael Schatz, Matthias Streun, Sven Jovanovic, Rüdiger-A Eichel, Simone S Köcher, Josef Granwehr","doi":"10.5194/mr-7-113-2026","DOIUrl":"10.5194/mr-7-113-2026","url":null,"abstract":"<p><p>Spectroelectrochemical nuclear magnetic resonance (NMR) experiments are faced with numerous challenges originating from shielding effects and susceptibility gradients in samples, leading to inhomogeneities in the static magnetic fields <math> <mrow><msub><mi>B</mi> <mn>0</mn></msub> </mrow> </math> and the radio frequency (rf) fields <math> <mrow><msub><mi>B</mi> <mn>1</mn></msub> </mrow> </math> . Moreover, magnetic feedback caused by eddy currents in conductors can obstruct precise measurements. Previous works have shown that these eddy-current-induced magnetic field distortions can be accurately predicted by finite element method (FEM) simulations. In this work, we present a workflow combining FEM predictions with quantum optimal control (QOC) to tailor custom NMR pulses that exploit specific magnetic field distortions for selective excitation of affected sample regions. The desired selectivity was achieved using pattern pulses optimized for either a particular <math> <mrow><msub><mi>B</mi> <mn>1</mn></msub> </mrow> </math> or Larmor frequency <math> <mrow><msub><mi>ν</mi> <mn>0</mn></msub> </mrow> </math> . Experimental validation was performed on a heterogeneous phantom consisting of two cavities filled with two spectroscopically distinguishable liquids, one between copper disks to mimic an electrochemical cell and one between polymer disks as a reference. An over 30-fold suppression of the reference resonance in between polymer compared to the resonance in between copper disks was achieved, demonstrating how QOC-tailored pulses can selectively address FEM-predicted <math> <mrow><msub><mi>B</mi> <mn>1</mn></msub> </mrow> </math> distortions in the vicinity of electrical conductors to achieve spatial selectivity with simultaneous <math> <mrow><msub><mi>ν</mi> <mn>0</mn></msub> </mrow> </math> robustness. It was also demonstrated how QOC-tailored pulses can selectively excite specific <math> <mrow><msub><mi>ν</mi> <mn>0</mn></msub> </mrow> </math> despite <math> <mrow><msub><mi>B</mi> <mn>0</mn></msub> </mrow> </math> distortions, which implies that difficulties with conventional solvent suppression techniques in electrochemical setups can be mitigated using the adjustable robustness of QOC-tailored pulses. The presented approach sets the stage for gradient-free, localized in operando NMR in electrochemistry and material sciences, with the prospect of surface selectivity down to the detection limit of the setup.</p>","PeriodicalId":93333,"journal":{"name":"Magnetic resonance (Gottingen, Germany)","volume":"7 2","pages":"113-123"},"PeriodicalIF":0.0,"publicationDate":"2026-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13430427/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148671559","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":"Segmented-overlap Fourier filtering and averaging (SOFFA) approach to improve concentration sensitivity of magnetic resonance spectra.","authors":"Jason W Sidabras","doi":"10.5194/mr-7-99-2026","DOIUrl":"10.5194/mr-7-99-2026","url":null,"abstract":"<p><p>The segmented-overlap Fourier filtering and averaging (SOFFA) data acquisition method is described in detail for magnetic resonance spectroscopy. In this work, the four processes that encompass the SOFFA data acquisition method are detailed: (i) oversampling spectral segments, (ii) Fourier block-filtering, (iii) segment-overlap averaging, and (iv) decimation. Three experimental examples are shown: first, conventional continuous-wave (CW) electron paramagnetic resonance (EPR) is compared to SOFFA-CW of a single reduced <math><mrow><mo>[</mo> <mn>4</mn> <mi>Fe</mi> <mtext>-</mtext> <mn>4</mn> <mi>S</mi> <msup><mo>]</mo> <mo>+</mo></msup> </mrow> </math> ( <math><mrow><mi>S</mi> <mo>=</mo> <mn>1</mn> <mo>/</mo> <mn>2</mn></mrow> </math> ) at concentrations of 1 mM, 100 <math><mrow><mi>µ</mi> <mi>M</mi></mrow> </math> , and 10 <math><mrow><mi>µ</mi> <mi>M</mi></mrow> </math> , showing an average increase in concentration sensitivity by a factor of 5.6 in a 100 min measurement time. Second, an experimental comparison of CW and SOFFA non-adiabatic rapid-scan (SOFFA-NARS) data with similar filter parameters and field modulation amplitude demonstrates a factor of 10.3 in signal-to-noise (SNR) improvement (32 min measurement time) for a 150 <math><mrow><mi>µ</mi> <mi>M</mi></mrow> </math> site-directed spin-labeled hemoglobin in 82 % glycerol at 18 <math><mrow><mi>°</mi> <mi>C</mi></mrow> </math> . Finally, an SNR-matched experiment of free TEMPO at 10 <math><mrow><mi>µ</mi> <mi>M</mi></mrow> </math> concentration is presented, where CW was performed at 400 scans (273 min) compared to SOFFA-CW with an overlap factor of 100 (20 min). Also shown is the effect of <math><mrow><mn>1</mn> <mo>/</mo> <mi>f</mi></mrow> </math> noise on these CW and SOFFA-CW experiments. Ultimately, the SOFFA algorithm achieves sensitivity enhancement by combining massive digital oversampling and out-of-band noise filtration with coherent spatial accumulation of highly overlapped spectral segments. The gains reported here are phenomenological and are grounded in established digital signal processing principles but are validated through experiments rather than closed-form analytical prediction. This fundamental restructuring of the acquisition chain successfully decouples high-frequency filtering from low-frequency averaging while providing a data collection scheme that suppresses <math><mrow><mn>1</mn> <mo>/</mo> <mi>f</mi></mrow> </math> noise. The SOFFA method can be implemented to perform real-time segmented processing and, combined with more sophisticated averaging methods, will push the state-of-the-art sensitivity in magnetic resonance spectroscopy.</p>","PeriodicalId":93333,"journal":{"name":"Magnetic resonance (Gottingen, Germany)","volume":"7 2","pages":"99-112"},"PeriodicalIF":0.0,"publicationDate":"2026-07-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13376679/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148581559","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":"Dual bilinear rotations.","authors":"Yannik T Woordes, Burkhard Luy","doi":"10.5194/mr-7-89-2026","DOIUrl":"10.5194/mr-7-89-2026","url":null,"abstract":"<p><p>Bilinear rotations imply differing rotations on a spin <math><mi>I</mi></math> depending on the presence or absence of a bilinear coupling Hamiltonian in connection to a heteronucleus <math><mi>S</mi></math> . As such, spin system selective inversions using BIRD elements, excitations using TANGO, or general (effective) rotations using BANGO and/or BIG-BIRD, as well as multiplicity-edited rotations, are achievable. So far, the well-defined rotations were only imposed on a single spin, e.g., <math><mi>I</mi></math> , while the coupled heteronucleus experienced only an inversion or no rotation at all. Here, we introduce dual bilinear rotations that simultaneously allow spin system selective manipulations on both spins <math><mi>I</mi></math> and <math><mi>S</mi></math> as compared to the coupled spin system <math><mrow><mi>I</mi> <mi>S</mi></mrow> </math> . Particularly with the advent of multi-receive experiments and/or super-sequences with the necessity of exciting and storing specific spin systems in a flexible way, this may open new possibilities in pulse sequence design. A general derivation of the approach is given, and a quadruple- <math><mi>J</mi></math> -resolved-type experiment for obtaining fully decoupled spectra optimized for different spin systems is introduced for demonstration.</p>","PeriodicalId":93333,"journal":{"name":"Magnetic resonance (Gottingen, Germany)","volume":"7 1","pages":"89-98"},"PeriodicalIF":0.0,"publicationDate":"2026-06-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13375272/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148474734","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":"Excitation of delocalized long-lived states of aliphatic protons at low and high magnetic fields.","authors":"Sebastiaan Van Dyck, Coline Wiame, Kirill F Sheberstov, Geoffrey Bodenhausen","doi":"10.5194/mr-7-81-2026","DOIUrl":"10.5194/mr-7-81-2026","url":null,"abstract":"<p><p>Long-lived states (LLSs) can be excited in geminal protons of aliphatic chains by mono- or poly-chromatic spin-lock-induced crossings (SLICs), i.e., by application of one or more selective radio frequency (RF) fields, to create delocalized population imbalances between states belonging to different symmetry under spin permutations. At low fields (in this work at 1.4 T or 60 MHz for proton NMR), these experiments are challenging due to the proximity of the chemical shifts and the need to consider the full untruncated <math><mi>J</mi></math> -coupling Hamiltonian. Five molecules were studied in this work: ethanolamine, lysine, vitamin B1, metronidazole, and phenoxyethylamine (POEA). For POEA and metronidazole, the LLSs are reported for the first time. Measurements were carried out at low and high magnetic fields (1.4 and 11.7 T or 60 and 500 MHz for protons) using 60 MHz Magritek and 500 MHz Bruker NEO spectrometers. The rates <math> <mrow><msub><mi>R</mi> <mi>LLS</mi></msub> <mo>=</mo> <mn>1</mn> <mo>/</mo> <msub><mi>T</mi> <mi>LLS</mi></msub> </mrow> </math> and <math> <mrow><msub><mi>R</mi> <mn>1</mn></msub> <mo>=</mo> <mn>1</mn> <mo>/</mo> <msub><mi>T</mi> <mn>1</mn></msub> </mrow> </math> were determined using monochromatic SLIC excitation at both fields. We describe strategies for optimizing SLIC conditions in cases where the signals of neighboring CH₂ groups are relatively close to each other.</p>","PeriodicalId":93333,"journal":{"name":"Magnetic resonance (Gottingen, Germany)","volume":"7 1","pages":"81-88"},"PeriodicalIF":0.0,"publicationDate":"2026-06-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13294830/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148347647","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":"Scalable modeling of multi-spin ensembles in SABRE hyperpolarization: a symmetry-based framework for zero and ultralow fields.","authors":"Danil Markelov, Alexander Snadin, Alexey Kiryutin, Danila Barskiy, Alexandra Yurkovskaya","doi":"10.5194/mr-7-53-2026","DOIUrl":"10.5194/mr-7-53-2026","url":null,"abstract":"<p><p>This work presents a theoretical framework for quantitative, scalable modeling of signal amplification by reversible exchange (SABRE) experiments under zero- and ultralow-field (ZULF) conditions. SABRE exploits the singlet spin order of parahydrogen to hyperpolarize nuclear spins of substrates without chemical modification, enhancing NMR signals. In the ZULF SABRE method, polarization transfer occurs in ultralow magnetic fields where Zeeman interactions are comparable to or weaker than scalar couplings, enabling coherent mixing of spin states and revealing interactions often suppressed at high fields. Our approach captures the full quantum dynamics of SABRE, including coherent evolution, chemical exchange, and relaxation, within a Liouville space formalism. We demonstrate that the Hamiltonian, relaxation, and exchange superoperators possess symmetry with respect to the total spin, allowing the dynamics to be rigorously restricted to the zero-quantum coherence subspace. This symmetry-based reduction yields a scalable framework for efficient simulation of multi-spin SABRE systems, allowing the treatment of arbitrary spin ensembles, including those containing <math> <mrow><msup><mi></mi> <mn>15</mn></msup> <mi>N</mi></mrow> </math> , <math> <mrow><msup><mi></mi> <mn>13</mn></msup> <mi>C</mi></mrow> </math> , <math> <mrow><msup><mi></mi> <mn>1</mn></msup> <mi>H</mi></mrow> </math> , and other nuclei. The approach is validated against full Liouville space calculations for small systems and is further applied to a 14-spin SABRE complex, demonstrating its ability to treat spin systems of a complexity well beyond the reach of conventional full Liouville space simulations. The framework thus provides a predictive tool for optimal polarization fields, ZULF NMR spectra, and the design of novel hyperpolarization experiments.</p>","PeriodicalId":93333,"journal":{"name":"Magnetic resonance (Gottingen, Germany)","volume":"7 1","pages":"53-79"},"PeriodicalIF":0.0,"publicationDate":"2026-05-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13197189/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148019262","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":"An open-access WebApp for inverse Laplace transform analysis of time-domain nuclear magnetic resonance signals.","authors":"Tiago B Moraes, Gustavo V Von Atzingen, Larissa P Mazzero, William S Mendes, Marina B Zacharias, Marcelo C B Cardinali","doi":"10.5194/mr-7-39-2026","DOIUrl":"10.5194/mr-7-39-2026","url":null,"abstract":"<p><p>Over recent years, compact and low-field time-domain nuclear magnetic resonance (TD-NMR) instruments have become increasingly available, expanding their use in the characterization of biomaterials across food, plant, and agro-industrial research. In this context, the inverse Laplace transform (ILT) has emerged as a powerful mathematical approach for extracting relaxation time distributions from TD-NMR signals. However, despite its widespread use, ILT analysis is often restricted to proprietary software or requires advanced expertise in numerical methods, limiting its accessibility to non-specialist users. In this work, we present an open-access WebApp for performing ILT analysis of TD-NMR signals in a transparent and user-friendly manner. The implemented algorithm is based on non-negative least squares combined with Tikhonov regularization and singular value decomposition, allowing robust inversion of ill-posed relaxation data. The platform supports the main TD-NMR experiments used in practice, including Carr-Purcell-Meiboom-Gill (CPMG), inversion recovery, and saturation recovery pulse sequences, and is compatible with data from instruments of any manufacturer. In addition to describing the mathematical formulation and implementation of the algorithm, a concise methodological discussion of ILT in the context of TD-NMR is provided. The performance of the WebApp is evaluated using both simulated datasets and representative experimental signals, demonstrating that the obtained relaxation time distributions are consistent with those produced by established ILT approaches. By lowering the barrier to advanced signal processing, the proposed WebApp represents a useful open scientific tool for research and teaching in magnetic resonance applications.</p>","PeriodicalId":93333,"journal":{"name":"Magnetic resonance (Gottingen, Germany)","volume":"7 1","pages":"39-51"},"PeriodicalIF":0.0,"publicationDate":"2026-04-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13126518/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147824577","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":"Accelerated ¹⁹F biomolecular magic-angle spinning NMR with paramagnetic dopants.","authors":"Lea M Becker, Giorgia Toscano, Anna Kapitonova, Rajkumar Singh, Undina Guillerm, Roman J Lichtenecker, Paul Schanda","doi":"10.5194/mr-7-29-2026","DOIUrl":"10.5194/mr-7-29-2026","url":null,"abstract":"<p><p>The advantageous characteristics attributed to the <math> <mrow><msup><mi></mi> <mn>19</mn></msup> <mi>F</mi></mrow> </math> nucleus have made it a popular target for nuclear magnetic resonance (NMR) once again in recent years. Aside from solution NMR, an increasing number of studies have been conducted applying solid-state magic-angle spinning (MAS) NMR to fluorine-labelled samples. Here, the high chemical shift anisotropy and strong dipolar couplings can be utilised to get structural insights into proteins and measure long distances. Despite increasing popularity and promising benefits, the sensitivity of biomolecular <math> <mrow><msup><mi></mi> <mn>19</mn></msup> <mi>F</mi></mrow> </math> MAS NMR often suffers from slow longitudinal <math> <mrow><msub><mi>T</mi> <mn>1</mn></msub> </mrow> </math> relaxation and therefore long recycle delays. In this work, we expand paramagnetic doping, an approach commonly used to reduce proton <math> <mrow><msub><mi>T</mi> <mn>1</mn></msub> </mrow> </math> relaxation times, to <math> <mrow><msup><mi></mi> <mn>19</mn></msup> <mi>F</mi></mrow> </math> -labelled biological samples. We study the effect of Gd(DTPA) and Gd(DTPA-BMA) on <math> <mrow><msup><mi></mi> <mn>19</mn></msup> <mi>F</mi></mrow> </math> <math> <mrow><msub><mi>T</mi> <mn>1</mn></msub> </mrow> </math> and <math> <mrow><msub><mi>T</mi> <mn>2</mn></msub> </mrow> </math> , and <math> <mrow><msup><mi></mi> <mn>13</mn></msup> <mi>C</mi></mrow> </math> <math> <mrow><msub><mi>T</mi> <mn>1</mn></msub> </mrow> </math> and <math> <mrow><msub><mi>T</mi> <mn>2</mn></msub> </mrow> </math> relaxation in a [5- <math> <mrow><msup><mi></mi> <mn>19</mn></msup> <msup><mi>F</mi> <mn>13</mn></msup> <mi>C</mi></mrow> </math> ]-tryptophan-labelled protein via <math> <mrow><msup><mi></mi> <mn>19</mn></msup> <mi>F</mi></mrow> </math> -detected MAS NMR experiments. The observed paramagnetic relaxation enhancement substantially reduces measurement times of <math> <mrow><msup><mi></mi> <mn>19</mn></msup> <mi>F</mi></mrow> </math> MAS NMR experiments without compromising resolution. Additionally, we report the chemical shift assignments of all four fluorotryptophan signals in the <math><mrow><mn>12</mn> <mo>×</mo> <mn>39</mn></mrow> </math> <math><mrow><mi>kDa</mi></mrow> </math> -large protein TET2 using a mutagenesis approach.</p>","PeriodicalId":93333,"journal":{"name":"Magnetic resonance (Gottingen, Germany)","volume":"7 1","pages":"29-37"},"PeriodicalIF":0.0,"publicationDate":"2026-04-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13123408/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147791713","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":"Bimodal Q-band probehead with improved signal-to-noise ratio in pulse electron paramagnetic resonance.","authors":"Vasyl Denysenkov, Alexey Fedotov, Burkhard Endeward, Thomas F Prisner","doi":"10.5194/mr-7-21-2026","DOIUrl":"10.5194/mr-7-21-2026","url":null,"abstract":"<p><p>In addition to the development of various resonators, the concept of a probehead equipped with an additional low-noise amplifier (LNA) is becoming increasingly popular to enhance the sensitivity of electron paramagnetic resonance (EPR) spectrometers. The low-noise-detection amplifier makes it possible to measure pulsed EPR signals with high sensitivity. However, a strong reflected pulse signal can cause saturation and deterioration of the LNA characteristics, which requires protection of the LNA (for example, by using a protection switch in front of the LNA), which, in turn, reduces the signal-to-noise ratio. To overcome these limitations, we propose using an EPR probehead based on a bimodal cavity with strong isolation between the input and output ports in combination with a low-noise amplifier connected to the cavity output. The experiments demonstrate a 4-fold increase in the signal-to-noise ratio (SNR) of a bimodal probehead operating in transmission mode compared to its operation in reflection mode, which was achieved thanks to the additional use of LNA. The performance of the probe was also compared with the Bruker EN 5107D2 probe available in our laboratory, which showed an improvement that can be achieved by increasing the SNR by 2 times due to additional LNA and isolation of the detection channel from the input signal and by 3.3 times due to a larger sample volume in the bimodal probe ( <math><mo>∼</mo></math> 20 <math><mrow><mi>µ</mi></mrow> </math> L) at Q-band frequencies compared to the Bruker one ( <math><mo>∼</mo></math> 6 <math><mrow><mi>µ</mi></mrow> </math> L). The developed probehead can be used together with commercial Bruker ELEXYS EPR spectrometers without modification of the microwave bridge.</p>","PeriodicalId":93333,"journal":{"name":"Magnetic resonance (Gottingen, Germany)","volume":"7 1","pages":"21-28"},"PeriodicalIF":0.0,"publicationDate":"2026-03-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13055999/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147640931","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}