Applied Magnetic Resonance最新文献

{"title":"Spatial selectivity by shaping the static field: sweet spots and spider legs","authors":"Mark S. Conradi,&nbsp;Stephen A. Altobelli","doi":"10.1007/s00723-023-01548-5","DOIUrl":"10.1007/s00723-023-01548-5","url":null,"abstract":"<div><p>There is increasing interest in spatially localized NMR, such as low-cost NMR devices for organ-specific measurements, possibly with single-sided magnets. One method for obtaining spatial selectivity (to restrict the results to a specific organ) is to shape the static field, so that spins outside the central “sweet spot” are off-resonance and can be filtered out from the detected signal. However, the laws of magnetostatics dictate that the central sweet region will have “spider leg” extensions (extending outward from the center) where the field strength is unchanged from the central region. We address here the relative volumes of the central region and spider legs. We consider shaped fields of cylindrical symmetry of various orders n, where n reflects the leading term in field variation along the symmetry axis (that is, Zⁿ). We find that this method of localization is unsuitable with low-order fields (2nd and 3rd orders), with a non-convergent fraction of volume in the spider legs. In these low-n cases, localization needs to be aided by a limited volume of rf field and/or by diffusion damping of echoes in regions of strong gradients. However, the fraction of volume residing in the spider legs becomes limited with higher-order fields, providing better localization. Results are also presented for two-dimensional fields.</p></div>","PeriodicalId":469,"journal":{"name":"Applied Magnetic Resonance","volume":"54 11-12","pages":"1689 - 1700"},"PeriodicalIF":1.0,"publicationDate":"2023-06-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"52148520","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":"Identification of Free Radicals Formed in Gamma-Irradiated Acetazolamide Using Electron Paramagnetic Resonance Spectroscopy","authors":"Kerem Sütçü,&nbsp;Y. Emre Osmanoğlu","doi":"10.1007/s00723-023-01551-w","DOIUrl":"10.1007/s00723-023-01551-w","url":null,"abstract":"<div><p>In this study, spectroscopic, dosimetric and stability characteristics of free radicals formed in acetazolamide (ACE) sample as a result of gamma irradiation in the range of 0–15 kGy were determined using electron paramagnetic resonance (EPR) spectroscopy. For this purpose, by interpreting the spectra of the sample in the 0–100 mW microwave power region, it was determined that two different radicals were formed in the sample. The structures formed after irradiation were attributed to CH₃OṄ-(radical I) and -OSOṄH (radical II) radicals. The g-values, hyperfine coupling constants and spectrum contribution ratios of these radicals contributing to the experimental spectrum were also calculated. It has been determined that radical II is quite stable both at high temperature and after a long storage period.\u0000</p></div>","PeriodicalId":469,"journal":{"name":"Applied Magnetic Resonance","volume":"54 8","pages":"737 - 750"},"PeriodicalIF":1.0,"publicationDate":"2023-06-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00723-023-01551-w.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4308905","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":"Stefan Berger: A Praeceptor of Magnetic Resonance","authors":"Dieter Sicker,&nbsp;Jörg Matysik","doi":"10.1007/s00723-023-01550-x","DOIUrl":"10.1007/s00723-023-01550-x","url":null,"abstract":"","PeriodicalId":469,"journal":{"name":"Applied Magnetic Resonance","volume":"54 7","pages":"657 - 660"},"PeriodicalIF":1.0,"publicationDate":"2023-06-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00723-023-01550-x.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4091038","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":"Mesopore Fractal Characteristics in Low-Permeability Sandstone Affected by High Temperature Using NMR","authors":"Shi Liu,&nbsp;Zhe Huang","doi":"10.1007/s00723-023-01549-4","DOIUrl":"10.1007/s00723-023-01549-4","url":null,"abstract":"<div><p>Effectively evaluating the pore structure in sandstone proves to be a difficult task in the field of oil and gas seepage in unconventional reservoirs. Fractal theory demonstrates great potential as a feasible evaluation method. In this paper, we perform transverse relaxation time <span>(T_{2})</span> spectrum tests of low-permeability sandstones subjected to high temperatures via low-field nuclear magnetic resonance (NMR). Introducing fractal theory, statistical analysis and quantitative characterization of pore structure from aspects of pore size distribution and fluid migration are carried out. Five types of pore characteristic fractal dimensions are calculated and the response relationship between fractal characteristics and physical parameters is established. The results demonstrate that the fractal dimension of the adsorption pores does not have fractal characteristics, while that of the seepage pores exhibits obvious fractal characteristics, as well as a strong negative correlation with temperature. This indicates the improvement of adsorption pore uniformity with increasing temperature and its gradual transition to an ordered state. The total pores and pores (corresponding to bound and movable water) exhibit fractal characteristics yet they are not as obvious as those of the seepage pores. An ideal negative correlation is formed with the fractal dimension of seepage pores and the porosity and permeability, indicating that the seepage pores following a high-temperature treatment have a decisive influence on the migration and storage capacity of the reservoir rock, while the extensive amount of developed adsorption pores have a poor connectivity with each other and their contribution to the physical quality of the rock is limited. The effect of high temperature leads to the development of seepage pores, accompanied by a significant increase in the complexity of large-scale pores, which intensifies the complexity and non-uniformity of the pore structure.</p></div>","PeriodicalId":469,"journal":{"name":"Applied Magnetic Resonance","volume":"54 8","pages":"719 - 735"},"PeriodicalIF":1.0,"publicationDate":"2023-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4037525","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":"Band Selective Excitation and (frac{pi }{2})-Rotation using Fourier Synthesis","authors":"Sambeda Sarkar,&nbsp;Navin Khaneja","doi":"10.1007/s00723-023-01547-6","DOIUrl":"10.1007/s00723-023-01547-6","url":null,"abstract":"<div><p>Band selective excitation is widely used in high resolution nuclear magnetic resonance (NMR) spectroscopy to suppress unwanted signals. This article proposes a simple and versatile approach to design such pulses to band selectively rotate the magnetization vector for a desired flip angle. A <span>(90^circ )</span> excitation pulse is designed by amplitude modulation obtained using Fourier series to bring the magnetization vector to the equator of the Bloch sphere. However, this excited magnetization vector is dispersed linearly on the equator with the offset frequency. <span>(180^circ )</span> hard pulses with a free evolution period are used to refocus the excited magnetization vector. The main advantages of this design are overall simplicity and analytical tractability, making it suitable for practical applications. Simulation for band selective excitation and band selective <span>(frac{pi }{2})</span>-rotation are presented to validate the theory. Experimental realization of the proposed pulse sequences is done on a 750 MHz spectrometer for a sample of <span>(99.5% text {D}_2text {O})</span> and <span>(0.5% text {H}_2text {O})</span>.</p></div>","PeriodicalId":469,"journal":{"name":"Applied Magnetic Resonance","volume":"54 7","pages":"699 - 718"},"PeriodicalIF":1.0,"publicationDate":"2023-05-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4804839","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":"Broadband EPR Spectroscopy of the Ground Electron State of the Fe4+ Impurity Ion in Amethyst","authors":"V. F. Tarasov,&nbsp;R. B. Zaripov,&nbsp;V. D. Scherbakov","doi":"10.1007/s00723-023-01545-8","DOIUrl":"10.1007/s00723-023-01545-8","url":null,"abstract":"<div><p>Fine structure of ground electron state of Fe⁴⁺ impurity ion in a natural amethyst crystal was studied by broadband electron paramagnetic resonance spectroscopy in the frequency range of 34–500 GHz. It is established that energy levels scheme consists of ground quasi-doublet Sz = ± 2, quasi-doublet S z= ± 1 and singlet Sz=0 with zero-field energies ± 4.9 GHz, 435.2 ± 45.4 GHz and 584 GHz, respectively. Parameters of effective spin Hamiltonian describing dependences of electron spin levels on magnetic field are determined.</p></div>","PeriodicalId":469,"journal":{"name":"Applied Magnetic Resonance","volume":"54 7","pages":"679 - 686"},"PeriodicalIF":1.0,"publicationDate":"2023-05-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4624247","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":"Clustering into Three Groups on a Quantum Processor of Five Spins S = 1, Controlled by Pulses of Resonant RF Fields","authors":"I. S. Pichkovskiy,&nbsp;V. E. Zobov","doi":"10.1007/s00723-023-01544-9","DOIUrl":"10.1007/s00723-023-01544-9","url":null,"abstract":"<div><p>We consider a quantum processor based on five qutrits represented by spins <i>S</i> = 1, which is driven by radio frequency (RF) pulses selective in transitions between adjacent levels. Numerical simulation of the implementation of the quantum-adiabatic clustering algorithm was performed on the example of partitioning a set of six points into three groups. We find the amplitudes and durations of rectangular RF pulses, as well as the durations of free evolution intervals in the control pulse sequence, which made it possible to engineer a time-dependent effective Hamiltonian in the discrete-time approximation. Also we studied the dependence of the implementation fidelity on the parameters. We took quadrupole nuclei as qutrits, but the results obtained will be useful for controlling quantum processors based on qutrits represented by other systems.</p></div>","PeriodicalId":469,"journal":{"name":"Applied Magnetic Resonance","volume":"54 7","pages":"661 - 677"},"PeriodicalIF":1.0,"publicationDate":"2023-05-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4552514","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":"Suitability of Latebra as a Skin Marker for Magnetic Resonance Imaging","authors":"Tomokazu Takeuchi,&nbsp;Norio Hayashi,&nbsp;Atsuya Fuju","doi":"10.1007/s00723-023-01546-7","DOIUrl":"10.1007/s00723-023-01546-7","url":null,"abstract":"<div><p>Light-colored yolk material inside an egg shows higher magnetic resonance (MR) signals than surrounding material, which is termed the latebra, has been studied previously. The purpose of this study was to evaluate the usefulness of the latebra as a skin marker by comparing with other MR imaging (MRI) markers. Four materials, namely latebra, mouth freshener, baby oil, and a marker from a medical company, were placed in plastic cases and scanned to examine their signal intensities by calculating the contrast with agar signal. These materials were then evaluated using five types of MR imaging techniques, and the contrast values of some of the materials were calculated and compared by performing Tukey’s multiple comparison test. The latebra showed quite high contrast values in T1 weighted images with fat suppression and diffusion weighted image. All materials used in this study were observed to produce stable results over a period of 3 months. The latebra can easily be obtained and, based on the results of this study, is suitable as an MRI skin marker.</p></div>","PeriodicalId":469,"journal":{"name":"Applied Magnetic Resonance","volume":"54 7","pages":"687 - 697"},"PeriodicalIF":1.0,"publicationDate":"2023-05-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4428454","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 (textrm{EuFe}_2textrm{As}_2) Magnetic Structure Revealed by ESR","authors":"Yurii Talanov,&nbsp;Ilnur Gimazov,&nbsp;Ruslan Zaripov,&nbsp;Kirill Pervakov,&nbsp;Vladimir Vlasenko,&nbsp;Vladimir Pudalov,&nbsp;Gregory Teitel’baum","doi":"10.1007/s00723-023-01540-z","DOIUrl":"10.1007/s00723-023-01540-z","url":null,"abstract":"<div><p>Magnetic state of the <span>(textrm{EuFe}_2textrm{As}_2)</span> single crystal was investigated by electron spin resonance (ESR). The ESR spectra of europium ions were registered in the temperature range from 250 to 4 K. To study the anisotropy, the in-plane angular dependences were investigated at temperatures of 15 K upon rotating a crystal around the <i>c</i>-axis. The data analysis shows that <span>(textrm{EuFe}_2textrm{As}_2)</span> is an antiferromagnet with an easy anisotropy plane. Moreover, the second-order easy magnetization axis is observed for each of the two types of magnetic domains related with structural twins arising from the tetragonal-to-orthorhombic crystal lattice transition.</p></div>","PeriodicalId":469,"journal":{"name":"Applied Magnetic Resonance","volume":"54 4-5","pages":"527 - 534"},"PeriodicalIF":1.0,"publicationDate":"2023-04-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4741472","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":"Magnetic Ordering in TlGa1-xFexSe2 Dilute Magnetic Semiconductors with Various Fe Dilution Ratios","authors":"Serdar Gökçe,&nbsp;Tofig Mammadov,&nbsp;Arzu Najafov,&nbsp;Savaş Berber,&nbsp;Faik Mikailzade,&nbsp;MirHasan Seyidov","doi":"10.1007/s00723-023-01539-6","DOIUrl":"10.1007/s00723-023-01539-6","url":null,"abstract":"<div><p>The results of the studies of structural and magnetic properties of Fe-doped <span>({mathrm{TlGaSe}}_{2})</span> (<span>({mathrm{TlGa}}_{1-mathrm{x}}{mathrm{Fe}}_{mathrm{x}}{mathrm{Se}}_{2})</span>) layered magnetic semiconductor grown with two different doping concentrations (<span>(x)</span>) are presented. Electron paramagnetic resonance (EPR) investigations revealed that Fe³⁺ ions are located at the centers of GaSe₄ tetrahedra formed by Se atoms and the site symmetry around Fe³⁺ centers are orthorhombic. The crystal field parameters of the structure have been calculated by fitting the orthorhombic spin Hamiltonian using rotation patterns of EPR spectra. The crystal field parameters and rhombicity ratio (<span>({lambda }^{^{prime}})</span>) estimated from magnetization and EPR measurements of <span>({mathrm{TlGa}}_{1-mathrm{x}}{mathrm{Fe}}_{mathrm{x}}{mathrm{Se}}_{2})</span> crystals are found to be larger and lower for samples with higher and lower dilution ratios respectively. Structural stability, electronic and magnetic properties of the Fe-doped <span>({mathrm{TlGaSe}}_{2})</span> four-layer slab were explored using density functional theory (DFT) calculations. We have found that substituting <span>(mathrm{Fe})</span> single dopant atom at the <span>(mathrm{Ga})</span> site, and the formation of substitutional <span>({mathrm{FeSe}}_{4})</span> complexes due to the strong hybridization between the electronic states of the dopants and the neighboring <span>(mathrm{Se})</span> atoms are geometrically and energetically favorable for <span>({mathrm{TlGa}}_{1-mathrm{x}}{mathrm{Fe}}_{mathrm{x}}{mathrm{Se}}_{2})</span>. Our calculations indicate that the magnetic coupling between Fe dopants and the neighboring <span>(mathrm{Se})</span> atoms is dominantly ferromagnetic. While weakly antiferromagnetic interactions between Fe–Fe dopants due to the super-exchange mechanism is favorable. The positive value of the Curie temperature together with the observed antiferromagnetic hysteresis loops as well as with the characteristic temperature dependence of magnetic susceptibility indicate the existence of combined antiferromagnetic and weak ferromagnetic ordering between interacting unpaired spin orbitals of Fe³⁺ ions in <span>({mathrm{TlGa}}_{1-mathrm{x}}{mathrm{Fe}}_{mathrm{x}}{mathrm{Se}}_{2})</span> compounds are important experimental confirmations of theoretical predictions. The saturation magnetization for <span>({mathrm{TlGa}}_{1-mathrm{x}}{mathrm{Fe}}_{mathrm{x}}{mathrm{Se}}_{2})</span> compound is found to increase with increasing of the Fe³⁺ dopant concentration.</p></div>","PeriodicalId":469,"journal":{"name":"Applied Magnetic Resonance","volume":"54 4-5","pages":"535 - 559"},"PeriodicalIF":1.0,"publicationDate":"2023-04-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00723-023-01539-6.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"5000177","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}