Новые публикации

https://elib.sfu-kras.ru/handle/2311/157928

A waveguide system consisting of a hexagonal array of resonators with the sixth-order symmetry is studied. Using deformations in the system obtained by permuting vertices on the coordination spheres and changing the constants of coupling between the resonators, the edge states have been obtained, the origin of which is explained by elementary means. The edge solutions are preserved for an array with the complex coupling constants

В статье рассматривается волноводная система, представляющая собой гексагональный массив резонаторов с симметрией шестого порядка. За счет деформаций в системе, получаемых перестановками вершин на координационных сферах и изменением значений констант связи между резонаторами, были получены краевые состояния, происхождение которых объясняется элементарными средствами. Краевые решения сохраняются для массива с комплексными константами связи

DOI: https://doi.org/10.1103/92fr-pxqn

Neutron diffraction experiments of TmFeO3 single crystals were performed in the external magnetic fields. The field along the 𝑐 axis increases temperature of spin-reorientation transition 𝑇SR from phase Γ⁢4 to Γ⁢2. Application of the field along 𝑏 axis led to the decrease of 𝑇SR and to the formation of new phases. Based on the temperature and field dependence of the Bragg reflection intensity, the configuration of magnetically induced phases was proposed.

https://doi.org/10.1016/j.ceramint.2026.01.345

Copper layered silicates MCuSi₄O₁₀ (M = Ca, Sr, Ba) are promising inorganic pigments exhibiting intense blue color and high reflectance in the near-infrared (700–2500 nm) region. In this work, these compounds were synthesized via a flux method with subsequent mechanochemical activation. According to X-ray diffraction (XRPD) data, increasing the M²⁺ cation radius in the Ca→Sr→Ba series expands the unit cell due to longer average M−O bonds, distorting the tetrahedral-planar [CuO₄]^6- polyhedron. While mechanochemical treatment reduces agglomerate size, it does not change the unit cell parameters. Color coordinates in the CIELab space vary systematically with cation radius, whereas mechanochemical processing significantly increases lightness (L∗) and leads to color hue convergence. The highest integral solar reflectance (R∗, %) in the NIR was found for SrCuSi₄O₁₀ (76 %) and BaCuSi₄O₁₀ (75 %). The presence of an SiO₂ impurity phase detected by IR spectroscopy in CaCuSi₄O₁₀ explains its lower integral solar reflectance (56 %) compared to the other compounds. The obtained results form a holistic understanding of the influence of crystal chemical factors and mechanical processing on the optical properties of MCuSi₄O₁₀ and can serve as a basis for the rational design of highly effective new generation pigments.

https://doi.org/10.1016/j.jmmm.2026.173904

The magnetic and magnetocaloric properties of epitaxial La_1-хK_хMnO₃ thin films (where K is a monovalent cation and x = 0.05–0.18), synthesized via a two-step process involving metal-organic chemical vapor deposition followed by isopiestic annealing, are presented. The magnetic entropy change (ΔS) and relative cooling power (RCP) were systematically evaluated under applied magnetic fields of up to 5 T. The films exhibit at high magnetic fields a pronounced magnetocaloric effect within the temperature range of 130–270 K. The maximum ΔS reaches up to 3.34 J/kg·K, and the RCP up to 310.7 J/kg, depending on the doping level. In contrast to bulk counterparts, the thin films demonstrate reduced magnetocaloric parameters, although the observed values are comparable to those reported for Gd-based thin films. These results emphasize the potential of thin-film structures both for the fundamental investigation of low-dimensional magnetocaloric phenomena and for the integration of magnetocaloric-active materials into microscale solid-state cooling systems. Further refinement of synthesis conditions and film architecture is essential to enhance performance and enable practical applications.

https://doi.org/10.1016/j.jmmm.2026.173900

Single crystals of spinel Fe3−�Mn�O4 were prepared by the flux method using a solvent based on Bi2Mo3O₁₂-B2O3-Na2O with the addition of gallium oxide Ga2O3. The structural features of the obtained samples were studied by powder and single crystal X-ray diffraction analysis. According to EDX data, the obtained Fe3−�Mn�O4 crystals contain gallium in the amount of 12% per formula unit. Differential scanning calorimetry, specific heat study and temperature and field dependences of magnetization of the obtained single crystal showed a significant reduction of the ferrimagnetic phase transition (�� = 380 K) relative the parent Fe2MnO4 compound (�� = 560–580 K). The observed feature is, to a large extent, affected by the Fe/Mn/Ga ratio and demonstrates the possibility of the tuning the ferrimagnetic transition temperature over a wide temperature range. The flux technique for the single crystals synthesis enables precise variation of the Ga, Mn and Fe concentration in the (Fe,Mn,Ga)3O4 allowing one to create the material with the needed magnetic properties. The obtained spinel compound was studied in a wide temperature range: 300–770 K by DSC and 4.2–600 K by magnetization measurements. Along with the high-temperature ferrimagnetic phase transition, anomalies of the temperature dependence of the magnetization in small fields (about � = 50–100 Oe) accompanied by significant thermal hysteresis were detected in the ordered phase at much lower temperatures about � = 150–170 K that has not been observed in the other relative compositions.

https://doi.org/10.1016/j.inoche.2026.116140

We report the first successful synthesis of polycrystalline EuREAgS₃ (RE = Tb, Tm, Yb) compounds. These new quaternary chalcogenides extend an ongoing series of materials produced via a sealed-ampoule method from EuS, RE₂S₃, Ag and S at 1170 K. Powder X-ray diffraction reveals that the compounds adopt high-temperature polymorphs with two distinct structures. EuTbAgS₃ crystallizes in cubic space group Fm3¯m, with a unit cell parameter of a = 5.7267(6) Å. In contrast, EuTmAgS₃ and EuYbAgS₃ form in trigonal space group R3¯m, with unit cell parameters of a = 3.9837(4) Å, c = 9.982(1) Å and a = 3.9763(2) Å, c = 9.9700(7) Å, respectively. Both structure types feature a single crystallographic site for the cations (Eu²⁺/RE³⁺/Ag⁺) and one for the S^2– anions, forming a three-dimensional framework of edge-sharing (Eu/RE/Ag)S₆ octahedra. The structural distinction arises from the different local symmetry at the shared cation site. A clear structural contraction is observed across the EuREAgS₃ series (RE = Tb, Dy, Ho, Tm, Yb), manifesting as a decrease in both unit cell volume and the average bond length d(Eu/RE/Ag–S) with the decreasing ionic radius, r(RE³⁺). Electronic structure analysis confirms that all synthesized compounds are semiconductors, with the measured direct and indirect band gaps ranging from 1.48 to 1.70 eV and from 0.62 and 1.34 eV, respectively.

https://doi.org/10.1016/j.ijbiomac.2026.150299

The paper describes the rational design and truncation of high-affinity DNA aptamer ApTnI12 targeting cardiac troponin I (cTnI), a key biomarker for early diagnosis of cardiac injury. By combining molecular modeling, surface plasmon resonance, and bioluminescent assay, a series of truncated variants of ApTnI12 were obtained and studied to elucidate the role of its structural elements in mediating the aptamer's affinity and specificity. The G-quadruplex motif was shown to be essential for maintaining the aptamer stability and to play a key role in the cTnI epitope recognition, during which the flanking duplex regions and loops significantly contributed to binding strength and specificity through electrostatic and hydrogen bonding interactions. The specificity of the aptamer consisting of only G-quadruplex was significantly reduced, highlighting the need for careful monitoring of its non-specific binding. A rationally designed random duplex aptamer variant achieved comparable affinity to SELEX-derived aptamers, though with a compromise in specificity. These findings emphasize the importance of balancing structural elements in the aptamer design and underscore the need for integrated computational and empirical approaches for developing aptamers with optimal performance in biosensing and therapeutic applications.

https://doi.org/10.1134/S1063784225700483

The coupling coefficients of disk-shaped dielectric resonators interacting through a two-conductors stripline resonator placed in the rectangular diaphragm of a metallic case have been studied. It has been found that the capacitive interaction of the resonators changes to inductive when the eigenfrequency of the stripline resonator is lower than those of dielectric resonators. This feature makes it possible to design small-size multicavity bandpass filters with additional capacitive and inductive couplings, which are expected to offer a high selectivity and a small spread of the group delay time in the passband. Using the electrodynamic analysis of a 3D model, a small-size 12th-order filter with center frequency f₀ = 3.925 GHz of the 45-MHz-wide passband has been synthesized. The width of the passband was measured at a level of 1 dB from the minimal loss level. In the designed filter, a two-conductors stripline resonator is used to provide differing-in-sign additional couplings between disk-shaped resonators and couple feed lines at the input and output. This improves the filter manufacturability and raises the mechanical strength of the device. The characteristics of the filter confirm that the proposed design is promising for creating small-size frequency-selective devices for space communication.

https://doi.org/10.1016/j.jmmm.2026.173900

Single crystals of spinel Fe3−�Mn�O4 were prepared by the flux method using a solvent based on Bi2Mo3O₁₂-B2O3-Na2O with the addition of gallium oxide Ga2O3. The structural features of the obtained samples were studied by powder and single crystal X-ray diffraction analysis. According to EDX data, the obtained Fe3−�Mn�O4 crystals contain gallium in the amount of 12% per formula unit. Differential scanning calorimetry, specific heat study and temperature and field dependences of magnetization of the obtained single crystal showed a significant reduction of the ferrimagnetic phase transition (�� = 380 K) relative the parent Fe2MnO4 compound (�� = 560–580 K). The observed feature is, to a large extent, affected by the Fe/Mn/Ga ratio and demonstrates the possibility of the tuning the ferrimagnetic transition temperature over a wide temperature range. The flux technique for the single crystals synthesis enables precise variation of the Ga, Mn and Fe concentration in the (Fe,Mn,Ga)3O4 allowing one to create the material with the needed magnetic properties. The obtained spinel compound was studied in a wide temperature range: 300–770 K by DSC and 4.2–600 K by magnetization measurements. Along with the high-temperature ferrimagnetic phase transition, anomalies of the temperature dependence of the magnetization in small fields (about � = 50–100 Oe) accompanied by significant thermal hysteresis were detected in the ordered phase at much lower temperatures about � = 150–170 K that has not been observed in the other relative compositions.

https://doi.org/10.1007/s10118-025-3516-2

The development of polymeric materials that exhibit blue thermally activated delayed fluorescence (TADF)0 is of great interest for optoelectronic applications. However, achieving TADF in polymers often requires an elaborate monomer design. The high-energy local triplet state (³LE) of carbazole complicates its application despite the molecular orbital arrangement being suitable for blue emission. Here, we present an approach to polymer design that makes it possible to solve this problem. We demonstrate the in situ formation of a TADF donor-acceptor system during Suzuki polycondensation, creating an extended carbazole-based donor matrix coupled00 with a triazine acceptor. The resulting polymer exhibited efficient TADF with a low energy gap (ΔE_ST) value if a phenyl N-substituent, enabling essential electron delocalization, was present in the carbazole moiety. This work establishes a versatile platform for developing carbazole-based TADF polymers, overcoming the fundamental limitations that hinder their widespread application.

https://doi.org/10.1007/s10948-025-07102-7

The ability to design magnetic anisotropy in one-dimensional nanostructures is a cornerstone of modern spintronics and data storage. Typically, the high aspect ratio of nanowires dictates a dominant shape anisotropy with an easy axis parallel to their length. Here, we demonstrate a dramatic reversal of this paradigm in composition-gradient Co-CoW nanowires. Using a tailored electrodeposition process, we fabricate nanowires with a smooth transition from crystalline hcp-Co at the base to an amorphous CoW alloy. Structural and elemental analysis confirms the controlled longitudinal gradient. Strikingly, magnetic characterization reveals an easy magnetization plane perpendicular to the nanowire long axis, a direct inversion of the conventional easy-axis orientation observed in homogeneous Co or CoW nanowires. This gradient-induced anisotropy is accompanied by a significant enhancement of transverse coercivity up to 250 Oe. The anisotropy field distribution and first-order reversal curve (FORC) analysis reveal a multiphase magnetic system where the magnetization switching is governed by coherent rotation and localized domain wall motion, driven by internal magnetostatic and magnetoelastic effects originating from the composition gradient. Our findings establish compositional grading as a powerful tool for designing unconventional magnetic anisotropies in functional nanomaterials.

https://doi.org/10.1364/AO.580680

Diffraction orders at the Pancharatnam–Berry metasurface are efficiently switched by applying voltage. A liquid crystal layer introduced acts as a half-wave phase plate to exchange left- and right-circular polarizations of light. Applied voltage turns the polarization exchange on and off, causing redistribution of the intensity between the −1 and +1 diffraction orders. The proposed novel, to our knowledge, structure features a multilayer substrate that supports the Tamm plasmon polaritons, enabling the integration of both resonant and non-resonant phase-change mechanisms.

https://doi.org/10.3390/cryst16010018

Rb₂KWO₃F₃ elpasolite was synthesized via the solid-state reaction route. The phase purity of the obtained sample was verified by the XRD analysis with Rietveld refinement in space group Fm-3m, yielding the unit cell parameter a = 8.92413 (17) Å. The electronic structure and chemical states of the constituent elements were investigated using X-ray photoelectron spectroscopy. The binding energy of the W 4f_7/2 core level (34.95 eV) was found to be characteristic of the W⁶⁺ oxidation state, while the values for Rb 3d, K 2p, O 1s and F 1s levels were consistent with those reported for related oxide and oxyfluoride compounds. First-principles density functional theory calculations were performed to model the electronic structure. The fac-configuration of the WO₃F₃ octahedra was identified as the most energetically favorable. The calculations revealed a direct band gap of 4.38 eV, with the valence band maximum composed primarily of O 2p orbitals and the conduction band minimum formed by W 5d orbitals. This combined experimental/theoretical study shows that the electronic structure and wide bandgap of Rb₂KWO₃F₃ are governed by the WO₃F₃ units and are largely insensitive to the Rb/K substitution. The wide bandgap identifies this class of oxyfluorides as a promising platform for developing new UV-transparent materials.

https://doi.org/10.1039/D5TC03374H

Cobalt-containing borates are emerging as multifunctional materials for optical devices, Li-ion and Na-ion battery anodes, and rare-earth-free permanent magnets. In particular, the phases Co₂B₂O₅, Co₃B₂O₆ and Co₃BO₅ – which incorporate Co²⁺ and Co³⁺ centers – can all be crystallized from closely related Bi₂O₃–MoO₃–Na₂O–B₂O₃ fluxes with only minimum compositional adjustments. In this study, we elucidate (1) high-temperature crystallization pathways in these multicomponent flux systems and (2) factors that stabilize Co in oxidation states +2 versus +3. By systematically varying the Na₂O/MoO₃/B₂O₃ ratio, we tune relative populations of Co²⁺- and Co³⁺-bearing species in the flux. We monitor the competitive formation of intermediate phases – Na₂MoO₄, CoMoO₄, Na₂B₄O₇ and putative NaCoO₂ – and show how these intermediates direct the ultimate borate phase. Moreover, by incrementally introducing NiO into the flux, we estimate solid solutions of the kotoite type (Co_3−xNi_xB₂O₆) and ludwigite type (Co_3−xNi_xBO₅) and map their phase boundary in unprecedented detail. This compositional “switch” controls whether Co³⁺-rich borates are formed. We report the first synthesis of Co_3−xNi_xB₂O₆ solid solutions within the range of 0 < x < 1, which has not been previously explored, revealing a magnetic ordering transition near 35 K. Crystals of Co₂B₂O₅ (pyroborate) and Co_3−xNi_xBO₅ ludwigites have also been grown. Comprehensive structural refinements and magnetic measurements of all the phases are presented to substantiate our mechanistic insights.

https://doi.org/10.1016/j.infrared.2026.106387

The spectral properties of ε-Fe₂O₃ nanoparticles of different sizes embedded in SiO₂ silica gel and xerogel matrices have been investigated by vibrational spectroscopy in the frequency range of 380‒4000 cm^‒1. The experimental data have been interpreted using the density functional theory calculation of the ε-Fe₂O₃ structure and phonon modes and the results obtained for the crystal, electronic, and vibrational structure have been found to agree well. Analysis of the dynamics of the spectra has shown that the main contribution to the IR spectra of ε-Fe₂O₃ nanoparticles in SiO₂ silica gel and xerogel matrices is made by bending vibrations of the FeOFe bond in the octahedron and tetrahedron. It has been established that the fraction of hydrogen bonds for nanoparticles with an average size of ∼2 nm is greater than for coarser particles. With an increase in the nanoparticle size, the crystallinity of nanoparticles grows.

https://doi.org/10.1016/j.cjph.2026.01.004

A comprehensive approach for simulating lasing dynamics in a liquid crystal based laser is presented. The approach takes into account the transformation of the liquid crystal structure caused by applied voltage. In particular, it allows us to explicitly account for a resonant mode frequency shift in the laser equations. The laser dynamic is described by a set of coupled non-linear differential equations for dye polarizations, population densities and the electromagnetic fields. The proposed model is applied to a photonic crystal - metal microcavity filled with a resonant nematic liquid crystal layer doped with a dye. The calculated lasing spectra governed by external electric field are verified in comparison with measured spectra.

DOI: 10.18083/LCAppl.2025.3.17

The orientation effects of pure and chlorophyll b (Chl. b)-doped nematic 5CB using the Faraday method and the Fredericksz transition have been investigated. To analyze these effects, the volume diamagnetic anisotropy ΔΧ, which was considered as an orientation parameter, was determined. This parameter is absent in the symmetric state of the system above the temperature TNI (transition of nematic phase into isotropic liquid) and it appears during spontaneous symmetry breaking, when the system passes to an asymmetric nematic state. A discrepancy between ΔΧ(H) dependences with increasing of magnetic field H was found. The discrepancy is caused by an increase in ΔΧ_LC of the liquid crystal due to the contribution ΔΧ_Chl of Chl. b due to the additional current induced in the porphyrin ring by the magnetic field. A decrease in the threshold field for the chlorophyll-doped nematic 5CB H_th = 3.18 kOe as compared with the value H_th = 3.55 kOe of pure 5CB was obtained. It is associated with an increase in ΔΧ_Chl due to the introduction of a chlorophyll porphyrin ring into the liquid crystal. Orientational transitions during minimization of free energy in a layer of pure and chlorophyll-doped nematic 5CB are considered.

https://doi.org/10.1016/j.ijbiomac.2026.150299

The paper describes the rational design and truncation of high-affinity DNA aptamer ApTnI12 targeting cardiac troponin I (cTnI), a key biomarker for early diagnosis of cardiac injury. By combining molecular modeling, surface plasmon resonance, and bioluminescent assay, a series of truncated variants of ApTnI12 were obtained and studied to elucidate the role of its structural elements in mediating the aptamer's affinity and specificity. The G-quadruplex motif was shown to be essential for maintaining the aptamer stability and to play a key role in the cTnI epitope recognition, during which the flanking duplex regions and loops significantly contributed to binding strength and specificity through electrostatic and hydrogen bonding interactions. The specificity of the aptamer consisting of only G-quadruplex was significantly reduced, highlighting the need for careful monitoring of its non-specific binding. A rationally designed random duplex aptamer variant achieved comparable affinity to SELEX-derived aptamers, though with a compromise in specificity. These findings emphasize the importance of balancing structural elements in the aptamer design and underscore the need for integrated computational and empirical approaches for developing aptamers with optimal performance in biosensing and therapeutic applications.

https://doi.org/10.1007/s10948-025-07130-3

The evolution with interaction of the electronic structure of the triangular Hubbard model, which is believed to be the parent model for describing the electronic structure of twisted bilayer dichalcogenides, is studied within the cluster perturbation theory using 13-site clusters. Local and non-local correlations are taken into account within a cluster, while the intercluster hopping is considered using perturbation theory. We obtain the evolution of the electronic structure from metal to insulator through the pseudogap state with increasing interaction. We show that this pseudogap state is characterized by the arc–like Fermi surface with maximum spectral weight located in the Γ−� directions. The energy distribution curves at the Fermi level are not characterized by a strong spectral function peak. Such momentum-dependent behavior of pseudogap suppression of spectral function is not typical for the most familiar pseudogap in doped cuprates in the presence of strong antiferromagnetic correlations and can lead to momentum-uniform pseudogap.

 http://crm-en.ics.org.ru/journal/article/3672/

The work presents an experimental study of the tree structure that occurs during a medical examination. At each meeting with a medical specialist, the patient receives a certain number of areas for consulting other specialists or for tests. A tree of directions arises, each branch of which the patient should pass. Depending on the branching of the tree, it can be as final — and in this case the examination can be completed — and endless when the patient’s goal cannot be achieved. In the work both experimentally and theoretically studied the critical properties of the transition of the system from the forest of the final trees to the forest endless, depending on the probabilistic characteristics of the tree.

For the description, a model is proposed in which a discrete function of the probability of the number of branches on the node repeats the dynamics of a continuous gaussian distribution. The characteristics of the distribution of the Gauss (mathematical expectation of x0�0, the average quadratic deviation of σ�) are model parameters. In the selected setting, the task refers to the problems of branching random processes (BRP) in the heterogeneous model of Galton – Watson.

Experimental study is carried out by numerical modeling on the final grilles. A phase diagram was built, the boundaries of areas of various phases are determined. A comparison was made with the phase diagram obtained from theoretical criteria for macrosystems, and an adequate correspondence was established. It is shown that on the final grilles the transition is blurry.

The description of the blurry phase transition was carried out using two approaches. In the first, standard approach, the transition is described using the so-called inclusion function, which makes the meaning of the share of one of the phases in the general set. It was established that such an approach in this system is ineffective, since the found position of the conditional boundary of the blurred transition is determined only by the size of the chosen experimental lattice and does not bear objective meaning.

The second, original approach is proposed, based on the introduction of an parameter of order equal to the reverse average tree height, and the analysis of its behavior. It was established that the dynamics of such an order parameter in the σ=const�=const section with very small differences has the type of distribution of Fermi – Dirac (σ� performs the same function as the temperature for the distribution of Fermi – Dirac, x0�0 — energy function). An empirical expression has been selected for the order parameter, an analogue of the chemical potential is introduced and calculated, which makes sense of the characteristic scale of the order parameter — that is, the values of x0�0, in which the order can be considered a disorder. This criterion is the basis for determining the boundary of the conditional transition in this approach. It was established that this boundary corresponds to the average height of a tree equal to two generations. Based on the found properties, recommendations for medical institutions are proposed to control the provision of limb of the path of patients.

The model discussed and its description using conditionally-infinite trees have applications to many hierarchical systems. These systems include: internet routing networks, bureaucratic networks, trade and logistics networks, citation networks, game strategies, population dynamics problems, and others.

DOI: https://doi.org/10.1103/f6y7-qtzc

The dynamics of domain walls (DWs) was systematically investigated in epitaxial Pd/Co/Pd(111) samples with different thicknesses of the Pd bottom layer and, as a consequence, different interface roughnesses in the creep and flow regimes. The DWs were displaced by the simultaneous action of driving out-of-plane (OOP) and symmetry-breaking in-plane (IP) magnetic fields. A pronounced asymmetry in the dependencies of the velocities of the DWs on the applied IP magnetic field, 𝑣⁡(𝐻𝑥), was observed in the creep regime, which was related to the dependence of the mobility of the DWs on their chirality, presumably due to a chiral damping. The investigated samples revealed different depinning fields due to different interface roughnesses. Notably, the asymmetry in the 𝑣⁡(𝐻𝑥) dependencies almost disappeared in the flow regime, regardless of the extent of asymmetry observed in the creep regime and the values of depinning fields in the samples. We explain this fact by the precessional dynamics of DWs in the flow regime, in which the chirality of DWs changes between left-handed to right-handed with a large frequency, thus making DWs achiral on average. This study would deepen the understanding of the chiral dynamics of DWs and advance the development of DW devices.

DOI: https://doi.org/10.1103/qlq6-b67j

The multiferroic ferroborate GdF⁢e3⁢(B⁢O3)4 with huntite-type structure exhibits magnetic ordering below 𝑇N=38 K and contains two magnetic subsystems associated with Gd and Fe ions. Competing anisotropies of these subsystems drive a spin-reorientation transition at 𝑇SR=10.7 K, switching the ground state from easy-axis to easy-plane. Using antiferromagnetic resonance, we investigate the spin dynamics across this transition. The observed incomplete softening of a magnon mode during both field- and temperature-induced spin-reorientation transitions indicates the first-order nature of the phase transition, which is accompanied by a discontinuous jump in the effective anisotropy field. We reproduce this behavior using a simple model that attributes the jump in the anisotropy field to the presence of an effective fourth-order anisotropy constant, responsible for the discontinuous character of the transition. Remarkably, for in-plane magnetic fields, we identify a new AFMR mode that persists from 12 K up to 𝑇N. This mode likely corresponds to the dynamics of a long-period incommensurate state, previously detected by resonant elastic x-ray scattering.

https://doi.org/10.1063/5.0302922

Efficient heating of magnetic nanoparticles by means of the ferromagnetic resonance method is demonstrated with the use of isotropic superparamagnetic nickel ferrite powder as an example. The kinetic heating curves Δ�(�) were measured at frequency of �=8.9GHz⁠. It is shown that the obtained Δ� values are fairly well described by theoretical expressions for the absorption of microwave energy in an isotropic superparamagnet. This imparts some basic quantification to the idea of magnetic hyperthermia that operates in the ultra-high frequency range.

DOI: 10.47475/2500-0101-2025-10-2-395-404

Heating of the ferrihydrite (Fe2O3 (H2O)), hematite (-Fe2O3), maghemite (-Fe2O3), cobalt ferrite (CoFe2O4) powders in the ferromagnetic resonance (FMR) mode has been studied. It is shown that the temperature increment is determined by the magnetization of the powders and depends linearly on the squared magnetic component of a microwave f ield. It is demonstrated by the example of CoFe2O4 that heating of magnetic powders in the FMR mode can occur by means of the natural ferromagnetic resonance. The Fe2O3 SiO2NH2 FAS9 composite particles capable of effectively binding to tumor cells of Ehrlich ascites carcinoma have been synthesized. It is shown that magnetic resonance hyperthermia leads to a decrease in the viability of tumor cells.

https://www.mathnet.ru/php/archive.phtml?wshow=paper&jrnid=jsfu&paperid=1296&option_lang=rus

Исследована возможность применения суперпарамагнитных наночастиц на основе магнетита с полисахаридным покрытием, функционализированных аптамером, для визуализации опухолей in vivo на примере асцитной карциномы Эрлиха с помощью МРТ. Синтезированные наночастицы исследованы методами просвечивающей электронной микроскопии, мессбауэровской спектроскопии и ферромагнитного резонанса. Синтезированные наночастицы конъюгировали с аптамером As42, специфичным к клеткам карциномы Эрлиха (As42-Fe${}_3$O${}_4$-AG). Показана возможность применения препарата As42-Fe${}_3$O${}_4$-AG в качестве контрастирующего агента для МРТ-визуализации опухолей у мышей, которые образовались в легких животных через 2 недели после внутрилегочного введения клеток асцитной карциномы Эрлиха. Аптамер AS42 адресно доставляет в опухолевые очаги суперпарамагнитные наночастицы на основе магнетита (Fe${}_3$O${}_4$-AG), которые контрастируют при МРТ сканировании ткани. Препарат позволяет специфично распознавать с помощью МРТ солидные опухоли легких, что подтверждается с помощью аутопсии.

https://doi.org/10.1134/S0040577925120128

Experimental studies of magnetic properties of a topological van der Waals antiferromagnet insulator MnBi2Te4 demonstrated not only an anomalous behavior of magnetization before and after the spin-flop transition but also its strong temperature dependence. To interpret these effects, we present a quantum theory of layered antiferromagnet with a trigonal symmetry of the triangular lattice. Using atomic representations for spin operators and the diagram technique for Hubbard operators, we obtain a dispersion equation describing the temperature dependence of the excitation spectrum. In the anisotropic self-consistent field approximation, we derive a transcendent equation establishing an interrelation between the Néel temperature and model parameters. For the weak-anisotropy case, we obtain its analytical solution. We describe the temperature evolution of magnetization as a function of magnetic field and construct a phase diagram showing regions where different configurations of MnBi2Te4 magnetic sublattices are realized. We observe that quantum effects induced by the trigonal component of the single-ion anisotropy essentially affect the thermodynamic properties of antiferromagnets

https://doi.org/10.3390/molecules30244794

Owing to the fact that ultrathin platinum films have many practical applications, the information concerning the initial stage of the formation of these films raises considerable interest. The effect of the film thickness on the morphology, as well as on the electrical and optical properties, was experimentally studied by a combination of methods (TEM, SAED, SEM, AFM, optical spectrophotometry, and electrical resistance measurements). The growth mechanisms of the films with an average thickness from 0.2 to 20 nm were determined, which is equivalent to the thickness of 1 to 100 monolayers (ML). The percolation threshold was reached, with the average film thickness being ≈1.0 nm, when electrical conductivity appeared. With an average thickness of ≈2.0 nm, the platinum films became almost continuous. The obtained data were analyzed within the framework of scaling theory. The growth of the platinum films at the initial stage (0.2–2.0 nm) was shown to proceed in the mixed 2D/3D growth mode. Here, 3D nanoislands, having a crystalline structure, were formed simultaneously with the formation of an almost continuous 2D subnanometer layer possessing an amorphous-like structure.

DOI: https://doi.org/10.1103/rq46-g378

We revise the temporal coupled mode theory to describe the resonant response of quasiguided modes under oblique incidence in periodic dielectric metasurfaces accounting for the constraints imposed by the symmetry of the unit cell. We derive a universal expression for the Fano resonance line shape in reflection and transmission for subwavelength period metasurfaces and reveal a fundamental link between the Fano parameters and unit cell symmetries, including robust reflection and transmission zeros, as well as spectral signatures of bound states in the continuum. To demonstrate the power of the developed theory, we provide a generalized framework for analyzing asymmetry in the coupling and decoupling coefficients. This allows us to reveal the dual nature of unidirectional guided resonances and counter-propagating modes characterized by single-sided coupling to incident waves, which have been actively discussed in recent years. These insights provide a powerful analytical tool for designing high-Q resonances in metasurfaces through symmetry exploitation.

https://doi.org/10.1016/j.optcom.2025.132836

Orthorhombic strontium tetraborate (α-SBO) is a prospective optical material for future high-power applications in DUV and VUV. Limitations of α-SBO as a nonlinear optical material can be overridden by the use of spontaneous random domain structures inherent to this unique material. The present article reports spatially selective random quasi phase matching of nonlinear optical conversion in random structures of α-SBO that resulted in more than two orders of magnitude efficiency enhancement for the frequency doubling to the blue spectral region due to employing excellent radiation damage resistance of α-SBO and selection of most efficient parts of random structure. Further progress to DUV and VUV generation is prognosed via the development of technology in the direction of obtaining thinner average thickness of domains.

https://doi.org/10.1016/j.omtn.2025.102790

The SARS-CoV-2 spike (S) protein, crucial for viral entry, remains a key target for diagnostics and therapeutics amid evolving variants. Here, we describe the selection and characterization of novel DNA aptamers targeting the S1 subunit, including the Omicron strain, via systematic evolution of ligands by exponential enrichment (SELEX) and biolayer interferometry (BLI). Three aptamers—AptS1-tSP4, AptS1-tSP10, and AptS1-tSP11—exhibited nanomolar dissociation constants (14–59 nM), with AptS1-tSP10 demonstrating good selectivity over MERS-CoV and robust binding in human saliva and pseudovirus samples. Integration with proximity ligation assay and qPCR (PLA-qPCR) achieved a detection limit of 3 pM, surpassing many antibody-based methods. Mass spectrometry-based epitope mapping identified the receptor-binding domain (RBD) peptide VGGNYNYLYR as the primary binding site for AptS1-tSP10. Molecular dynamics and quantum mechanics simulations revealed stable interactions through hydrogen bonding and π-π stacking with neutral residues in both open and closed spike conformations, independent of variant mutations. These multifunctional aptamers offer a versatile platform for ultrasensitive, epitope-specific SARS-CoV-2 detection and pave the way for nucleic acid-based therapeutics to combat viral infections.