Applied Magnetic Resonance最新文献

{"title":"Semiclassical Magnetization Dynamics and Electron Paramagnetic Resonance in Presence of Magnetic Fluctuations in Strongly Correlated Systems","authors":"S. V. Demishev","doi":"10.1007/s00723-023-01638-4","DOIUrl":"10.1007/s00723-023-01638-4","url":null,"abstract":"<div><p>Semiclassical magnetization dynamics in presence of magnetic fluctuations (including the quantum ones) is derived for a strongly correlated electronic system in the region of the linear magnetic response. Landau–Lifshitz (LL) and Gilbert (G) type equations are obtained with the effective parameters depending on the type of magnetic fluctuations and their magnitude and applied to evaluation of electron paramagnetic resonance (EPR) problem in Faraday geometry. It is shown that in the studied systems LL and G equations may not be equivalent except the case of weak relaxation, where consistent Landau–Lifshitz–Gilbert (CLLG) equation may be considered. Whereas G equation is affected by quantum fluctuations solely, the LL and CLLG equations may be renormalized by magnetic fluctuations of any nature. In contrast to G equation, the LL and CLLG magnetization dynamics may be characterized by the anisotropic relaxation term caused by anisotropic magnetic fluctuations. A consequence of anisotropic relaxation is the unusual polarization effect consisting in strong dependence of the EPR line magnitude on orientation of vector <b>h</b> of the oscillating magnetic field with respect to the crystal structure, so that EPR may be suppressed for some directions of <b>h</b>. In the case of dominating quantum fluctuations, the LL and CLLG equations may lead to a universal relation between fluctuation induced contributions to the EPR line width Δ<i>W</i> and g-factor Δ<i>g</i> in the form <span>(Delta W/Delta g = a_{0} k_{B} T/mu_{B})</span>, where <i>a</i>₀ is a numerical coefficient of the order of unity and independent of the quantum fluctuation magnitude. The applicability of the proposed semiclassical magnetization dynamics models to the EPR in spin nematic phases and detection by EPR method of a new group of magnetic phenomena – spin fluctuation transitions is discussed.</p></div>","PeriodicalId":469,"journal":{"name":"Applied Magnetic Resonance","volume":"55 9","pages":"1091 - 1114"},"PeriodicalIF":1.1,"publicationDate":"2024-01-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139585104","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Wayne Hubbell: On the Occasion of His 80th Birthday","authors":"Zhongyu Yang,&nbsp;Candice Klug,&nbsp;Miyeon Kim","doi":"10.1007/s00723-023-01639-3","DOIUrl":"10.1007/s00723-023-01639-3","url":null,"abstract":"","PeriodicalId":469,"journal":{"name":"Applied Magnetic Resonance","volume":"55 1-3","pages":"1 - 4"},"PeriodicalIF":1.1,"publicationDate":"2024-01-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139077968","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Features of the Primary Electron Spin Echo Signal for Spin-Correlated Radical Pairs","authors":"K. M. Salikhov,&nbsp;A. A. Sukhanov,&nbsp;I. T. Khairutdinov","doi":"10.1007/s00723-023-01636-6","DOIUrl":"10.1007/s00723-023-01636-6","url":null,"abstract":"<div><p>The phase of the primary electron spin echo signal was analyzed on model radical pairs (RPs) in a singlet spin state. An interpretation is given of the fact known in the literature that the echo signal of such pairs may not have a component with a “normal” phase, which is expected for the echo signal of non-interacting unpaired electrons in the RP. For the first time, it has been theoretically shown that forbidden EPR transitions can make a significant contribution to the phase shift of the magnetization of RP spins, caused by the dipole–dipole hyperfine interaction of unpaired RP electrons with magnetic nuclei. The “anomalous” phase of the spin echo signal of interacting spins in radical pairs is a demonstration that spin dynamics is accompanied by reversible transitions of dipole polarization (spin magnetization) and quadrupole spin polarization.</p></div>","PeriodicalId":469,"journal":{"name":"Applied Magnetic Resonance","volume":"55 4","pages":"463 - 475"},"PeriodicalIF":1.1,"publicationDate":"2023-12-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139066667","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Probing the “Dead-Time” in NMR by Combining Single Pulse and Solid Echo Experiments Followed by a Global Model Fit Analysis","authors":"Eddy Walther Hansen","doi":"10.1007/s00723-023-01637-5","DOIUrl":"10.1007/s00723-023-01637-5","url":null,"abstract":"<div><p>The main question addressed in this work is how to probe the “effective dead-time” in an NMR instrument, i.e., the time needed to blank the receiver after an rf-pulse excitation to prevent damage to the receiver and to avoid any distortion of the NMR signal being sampled. The strategy is to design a suitable FID-model to fit the single pulse excitation (SPE) and solid echo pulse (SEPS) data (on solid Tricosane) using a Global model-fit analysis technique. The derived dead time is discussed with respect to sampling temperature (25–40 °C) and—in particular—with respect to the number of SEPS data involved in the Global fit analysis by applying the Bayesian Information Criterion (BIC) in combination with more traditional statistical analysis. It is concluded that the “effective dead time” can be determined within a standard error of less than 2.5%.</p></div>","PeriodicalId":469,"journal":{"name":"Applied Magnetic Resonance","volume":"55 4","pages":"477 - 496"},"PeriodicalIF":1.1,"publicationDate":"2023-12-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00723-023-01637-5.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139057468","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Magnetic Resonance Express Analysis and Control of NV− Diamond Wafers for Quantum Technologies","authors":"Roman A. Babunts,&nbsp;Aleksandr S. Gurin,&nbsp;Yulia A. Uspenskaya,&nbsp;Kirill V. Likhachev,&nbsp;Valentina V. Yakovleva,&nbsp;Anastasia V. Batueva,&nbsp;Artyom M. Skomorokhov,&nbsp;Igor P. Veyshtort,&nbsp;Maxim V. Uchaev,&nbsp;Marat K. Eseev,&nbsp;Viktor G. Vins,&nbsp;Alexander P. Yelisseyev,&nbsp;Zulfiya F. Urmantseva,&nbsp;Pavel G. Baranov","doi":"10.1007/s00723-023-01632-w","DOIUrl":"10.1007/s00723-023-01632-w","url":null,"abstract":"<div><p>Magnetic resonance methods for express analysis and control of diamond wafers with NV⁻ centers for quantum technologies were developed. The scanning NV⁻-based ODMR spectrometer was built to analyze NV⁻ local concentration, coherent properties, stress/strain, nitrogen content, electron-nuclear interactions in diamond wafers for quantum technologies. As an example, a 3D image of the ODMR and PL maps was presented for a non-uniform distribution of NV⁻ centers in a diamond wafer, which had several growth zones with significantly different concentrations of nitrogen. The local stress/strain map was obtained by measuring the splitting of the ODMR line in zero magnetic field at room temperature. The double ODMR line is a consequence of the stress-induced splitting of the doublet with projections M_S = + 1 and M_S = − 1 in the ground triplet state of the NV⁻ center. Local concentration of nitrogen donors (in EPR literature it is designated as N or P1 centers) was estimated from the ratio of the intensity of satellites caused by interaction with nitrogen donors and the central line of ODMR. The central line has a 2E split into two overlapping lines, the intensity of one of the lines is selected. The spectrometer is also designed to perform pulsed measurements of Rabi oscillations, spin–lattice and spin–spin relaxation times at wafer points isolated by focused laser excitation. A new option for using a spectrometer was introduced for measuring the ODMR of NV⁻ centers in a linearly polarized light, which allowed to distinguish PL for centers of a certain orientation and suppress the PL from others.</p></div>","PeriodicalId":469,"journal":{"name":"Applied Magnetic Resonance","volume":"55 4","pages":"417 - 428"},"PeriodicalIF":1.1,"publicationDate":"2023-12-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138686577","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Solution NMR Studies of LPRDA Peptide: an Oligopeptide Inhibitor of Staphylococcus aureus Sortase A","authors":"Evgenii S. Kuchaev,&nbsp;Sergey V. Efimov,&nbsp;Alexander V. Klochkov,&nbsp;Albert V. Aganov,&nbsp;Polina M. Ivantcova,&nbsp;Konstantin V. Kudryavtsev,&nbsp;Konstantin S. Usachev","doi":"10.1007/s00723-023-01635-7","DOIUrl":"10.1007/s00723-023-01635-7","url":null,"abstract":"<div><p>Sortases are Gram-positive bacterial extracellular transpeptidases involved in the attachment of surface proteins to the cell wall. The mechanism of action of Staphylococcus aureus Sortase A (SrtA) is based on specific recognition of the LPXTG motive at the C-terminus of the surface protein, cleavage of this site between threonine and glycine residues, subsequent transfer of the N-terminal transmembrane domain to the amino group of the pentaglycine linker and thus anchoring of proteins with this motive on the cell surface. As SrtA is involved in both early and late stages of bacterial infection because it attaches adhesins and immune evasion proteins to the cell wall, this enzyme is a good target for combating bacterial infections. The oligopeptide LPRDA was recently found to be an effective inhibitor of the enzymatic activity of SrtA through competitive binding to its active site. By NMR spectroscopy we solved the solution structure of the LPRDA peptide and showed the presence of several conformers in solution. The obtained data are the basis for further studies of the structure and function of peptidomimetics based on LPRDA oligopeptide.</p></div>","PeriodicalId":469,"journal":{"name":"Applied Magnetic Resonance","volume":"55 4","pages":"451 - 461"},"PeriodicalIF":1.1,"publicationDate":"2023-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138686579","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Synthesis and Magnetic Properties of the Nd3+ Ion in the CsCaF3 Single Crystal","authors":"M. L. Falin,&nbsp;V. A. Latypov,&nbsp;S. L. Korableva","doi":"10.1007/s00723-023-01634-8","DOIUrl":"10.1007/s00723-023-01634-8","url":null,"abstract":"<div><p>A CsCaF₃ single crystal doped with Nd³⁺ ions is studied using electron paramagnetic resonance spectroscopy. A paramagnetic Nd³⁺ center of trigonal symmetry is recorded. The parameters of the corresponding spin Hamiltonians, the ground states and their wave functions are determined. Structural models of the observed complexes are proposed. The experimental results are analyzed in comparison with those for the same paramagnetic ion in other lattices.</p></div>","PeriodicalId":469,"journal":{"name":"Applied Magnetic Resonance","volume":"55 4","pages":"443 - 449"},"PeriodicalIF":1.1,"publicationDate":"2023-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138686581","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Applying a Power and Gender Lens to Understanding Health Care Provider Experience and Behavior: A Multicountry Qualitative Study.","authors":"Pooja Sripad, Summer Peterson, Daoudou Idrissou, Martha Kamanga, Abigail Kezembe, Charity Ndwiga, Chantalle Okondo, Anja Noeliarivelo Ranjalahy, Natacha Stevanovic-Fenn, Charlotte E Warren, Brady Zieman, Sanyukta Mathur","doi":"10.9745/GHSP-D-22-00420","DOIUrl":"10.9745/GHSP-D-22-00420","url":null,"abstract":"<p><p>A limited but growing body of literature shows that health care providers (HCPs) in reproductive, maternal, and newborn health face challenges that affect how they provide services. Our study investigates provider perspectives and behaviors using 4 interrelated power domains-beliefs and perceptions; practices and participation; access to assets; and structures-to explore how these constructs are differentially experienced based on one's gender, position, and function within the health system. We conducted a framework-based secondary analysis of qualitative in-depth interview data gathered with different cadres of HCPs across Kenya, Malawi, Madagascar, and Togo (n=123). We find across countries that power dynamics manifest in and are affected by all 4 domains, with some variation by HCP cadre and gender. At the service interface, HCPs' power derives from the nature and quality of their relationships with clients and the community. Providers' power within working relationships stems from unequal decision-making autonomy among HCP cadres. Limited and sometimes gendered access to remuneration, development opportunities, material resources, supervision quality, and emotional support affect HCPs' power to care for clients effectively. Power manifests variably among community and facility-based providers because of differences in prevailing hierarchical norms in routine and acute settings, community linkages, and type of collaboration required in their work. Our findings suggest that applying power-and secondarily, gender lenses-can elucidate consistencies in how providers perceive, internalize, and react to a range of relational and environmental stressors. The findings also have implications on how to improve the design of social behavior change interventions aimed at better supporting HCPs.</p>","PeriodicalId":469,"journal":{"name":"Applied Magnetic Resonance","volume":"50 7","pages":""},"PeriodicalIF":2.5,"publicationDate":"2023-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10698231/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72449952","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Automatic Optimization of Pulse Sequences Based on a Closed-Loop Control Strategy","authors":"Guanghui Shi,&nbsp;Lizhi Xiao,&nbsp;Guangzhi Liao,&nbsp;Sihui Luo,&nbsp;Xueli Hou,&nbsp;Huaxue Liu,&nbsp;Jian Zhong,&nbsp;Jihong Liu","doi":"10.1007/s00723-023-01633-9","DOIUrl":"10.1007/s00723-023-01633-9","url":null,"abstract":"<div><p>Generally, the pulse sequence parameters and acquisition parameters of nuclear magnetic resonance (NMR) logging tools are determined before logging and kept unchanged during logging. Because the detection area changes constantly during logging, the preset parameters are often not the best for different detection objectives, the energy consumption and sampling resolution will be reduced. To solve this problem, we propose a closed-loop control scheme for parameter optimization, which achieves the dynamic regulation of parameters according to the relaxation characteristics of the samples. The closed-loop control system has been implemented in a laboratory core analyzer to prove the effectiveness of the variable TE sequence as a reconnaissance sequence. When the sample changes, the control system can guide the control circuit to switch to the Carr-Purcell-Meiboom-Gill (CPMG) pulse sequence with appropriate parameters in a timely manner. Compared with conventional parameter setting methods, this scheme can better avoid insufficient attenuation of the echo train or excessive data collection caused by the improper setting of pulse train length while reducing energy consumption during measurements.</p></div>","PeriodicalId":469,"journal":{"name":"Applied Magnetic Resonance","volume":"55 4","pages":"429 - 441"},"PeriodicalIF":1.1,"publicationDate":"2023-11-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138508263","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Site-Directed Fluorescence Labeling (SDFL): TrIQ Methods Provide Insights Using the Fluorescent Probe Bimane","authors":"Anthony D. Shumate,&nbsp;David L. Farrens","doi":"10.1007/s00723-023-01628-6","DOIUrl":"10.1007/s00723-023-01628-6","url":null,"abstract":"<div><p>This review is in honor of Professor Wayne Hubbell’s 80th birthday, and his many contributions to the philosophy and practice of science. He continues to pioneer the use of site-directed spin labeling (SDSL) as a powerful tool for studying protein structure and dynamics. Inspired by his efforts, our lab has worked to develop site-directed fluorescence labeling (SDFL) as a complementary approach to SDSL. Throughout this process, we have emulated many of the novel methods and concepts Dr. Hubbell and his colleagues used during their development of SDSL. Some of our approaches are discussed here, not in a comprehensive or exhaustive way, but to highlight SDFL methods we have found to be robust, reproducible, and relatively easy to use. Specifically, we will focus on the development and application of SDFL using the fluorescent probe bimane, and how the unique properties of bimane can be exploited to glean information about protein structure and function. We also review past examples of how we have used bimane and SDFL to investigate the activation of G protein-coupled receptors (GPCRs) and their interaction with key binding partners.</p></div>","PeriodicalId":469,"journal":{"name":"Applied Magnetic Resonance","volume":"55 1-3","pages":"101 - 126"},"PeriodicalIF":1.1,"publicationDate":"2023-11-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138508274","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}