Applied Magnetic Resonance最新文献

The extreme complexity of petroleum products makes the detection and monitoring of their physicochemical properties a persistent challenge in petroleum refining. Low-field nuclear magnetic resonance (LF-NMR) technology, particularly time-domain nuclear magnetic resonance (TD-NMR), is a rapid and non-destructive technique for characterizing fluid states and properties and has become a valuable tool for detecting and monitoring state changes during petroleum refining processes. Because it is simple, cost-effective, and requires minimal sample preparation, LF-NMR is well suited to the determination of composition, content and other key physicochemical parameters when ultra-high resolution analysis is not required. This review summarizes the applications of LF-NMR in petroleum refining processes, including physical property determination, chemical composition analysis, mixture analysis and porous material characterization. Current methodological limitations are also discussed, and future directions are proposed to support safer and high-quality refinery operations.

The properties YGa₃(BO₃)₄ and EuGa₃(BO₃)₄ crystals doped with Mn²⁺ were investigated by electron paramagnetic resonance (EPR) and X‑ray diffraction methods in the temperature range 4–295 K. It was established that Mn²⁺ impurity ions substitute trivalent rare‑earth ions while preserving the symmetry of the substitution site. Heating of the crystals is accompanied by a smooth decrease in the splitting of the ground S state (spin S = 5/2) of the manganese ion.

The article summarizes the results of observation of cross-relaxation resonances discovered during studies of optically detected magnetic resonance in dielectric and semiconductor crystals conducted at the Ioffe Institute. The following phenomena are considered: cross-relaxation between optically pumped F-centers and impurity defects in irradiated crystals of alkali halides doped with thallium and indium, detected by monitoring magnetic circular dichroism in the absorption of F-centers; the Ce³⁺—Gd³⁺ cross-relaxation registered via the luminescence of Ce³⁺ in garnet crystals co-doped with cerium and gadolinium; cross-relaxation in the photoluminescence of localized heavy-hole excitons in GaAs/AlAs superlattices; cross-relaxation between NV centers and loosely coupled pairs of substitutional nitrogen atoms in diamond, and cross-relaxation between optically active S = 3/2 vacancy centers and other defects in silicon carbide.

The multi-echo turbo spin-echo (ME-TSE) method shortens acquisition time as the turbo spin-echo (TSE) factor increases; however, its influence on T₂ value measurement remains unclear. Using the ME-TSE method, this study evaluated the error rates in T₂ measurements caused by TSE factor variation. Sixty-three bottle phantoms were created by combining contrast agent and agar at different concentrations. Imaging was performed on a 1.5-T magnetic resonance imaging system using the multi-echo spin-echo (ME-SE) or ME-TSE method, with the TSE factor ranging from 2 to 10. The relative difference rates for T₂ values were calculated based on the difference between each TSE factor and the reference (ME-SE). Higher TSE factors increased relative difference rates in phantoms with shorter T₂ values, whereas relative difference rates decreased in phantoms with longer T₂ values. Considering the balance between acquisition time and relative error, a TSE factor of 3 was deemed optimal, although it depends on the target T₂ value of the measurement.

The methods of application of a magnon Bose–Einstein condensate as a multiparticle spinor qubit are proposed. The basic principles of its operation are considered using the example of a Bose–Einstein condensate of magnons in superfluid (^3)He-B. Potential advantages of its application for quantum computing are demonstrated. In particular, a parallel method for reading the results of quantum computations on a multiparticle qubit is proposed. The feasibility of performing quantum computations on yttrium iron garnet films at room temperature is explored.

This review discusses the evolution of quantum optical magnetometers intended for biomagnetic measurements, with particular emphasis on magnetoencephalography. The development of modern optically pumped magnetometers has gradually shifted from the pursuit of ultimate magnetic sensitivity toward suitability for dense multichannel arrays. We describe the evolution of nonzero-field all-optical sensors, including single-beam design, operation in the ultra-low-field regime, vector measurements, and fiber-based optical power distribution. Taken together, these developments demonstrate that high-performance biomagnetic sensing can be achieved without RF excitation and with simplified optical layout, making all-optical nonzero-field Bell–Bloom magnetometers a promising platform for distributed neurodiagnostic systems.

Analytical expressions have been derived for the parameters of the spin Hamiltonian of the transferred hyperfine interaction in CaF₂:Pu³⁺. It has been established that the parameter A_s of the spin Hamiltonian of this interaction is mainly due to charge transfer processes to the excited 5f⁴6d states. The covalency parameters have been estimated using the experimental electron–nuclear double resonance data on CaF₂:Pu³⁺. The splitting of the excited 5fⁿ⁻¹6d configurations under the influence of the crystal field has been studied. It has been shown that the splitting of the 6d electron state leads to an increase in the efficiency of the transfer of the hyperfine interaction from the Pu³⁺ ion to the fluorine nuclei via π bonds and a decrease in the efficiency of the transfer via σ bonds.

MucR is a conserved global regulator in α-proteobacteria, essential for virulence in Brucella and symbiotic adaptation in rhizobia. It primarily acts as a xenogeneic silencer, repressing AT-rich horizontally acquired genes. Structurally, MucR comprises an N-terminal oligomerization domain, a linker region, and a C-terminal zinc finger DNA-binding domain. Here, we report the optimization of NMR experimental condition and NMR resonance assignments for the complex formed by the C-terminal DNA-binding domain of MucR and 3A3T-DNA. Nearly complete assignments are obtained for ¹H, ¹³C, and ¹⁵N resonances of the protein and ¹H resonances of 3A3T-DNA. Histidine tautomeric state analysis confirms that the two zinc-coordinating histidine residues adopt N^δ1–H tautomeric state. Additional NMR-based analyses provided structural insights into the MucR^CTD and DNA complex formation. The NMR assignments provide a good basis for further structural study of the DNA binding and recognition mechanism of MucR.