New Publications

DOI:https://doi.org/10.1103/PhysRevB.110.035410

We study the effects of relaxation/decoherence processes on quantum transport of noninteracting Fermi particles across the disordered tight-binding chain, where we distinguish between relaxation processes in the contacts (external decoherence) and those in the chain (internal decoherence). It is shown that external decoherence reduces conductance fluctuations but does not alter the Anderson localization length. This is in strong contrast with the effect of internal decoherence which is found to suppress Anderson localization. We also address quantum transport in chains with particle losses which are of considerable interest for laboratory experiments with cold atoms.

https://doi.org/10.1016/j.mtcomm.2024.109623

Utilizing density functional theory (DFT), we embarked on a comprehensive investigation of the structural, electronic, and optical properties characteristic of the ferroelectric hybrid (Me2NH2)[NaFe(CN)5(NO)] crystal. The geometry of the crystal structure in the ���21 phase was optimized. We simulated the electronic band structure within the first Brillouin zone. The calculated band gap for the indirect U-X transition is 2.401 eV, indicative of a wide band gap semiconductors. We also simulated the density of electronic states across the Brillouin zone. The simulation of the electronic structure revealed that the crystal comprises both ionic and covalent bonds. We accurately predicted various optical parameters including the dielectric function, conductivity, reflectivity, loss function, absorption, and refractive index. The reflectivity of the crystal does not exceed 21 percent. All calculated optical properties of the (Me2NH2)[NaFe(CN)5(NO)] crystal are anisotropic.

https://doi.org/10.1016/j.jmmm.2024.172287

The structural, electrical, magnetic, magneto-optical properties and magnetoresistance of {[(Co₄₀Fe₄₀B₂₀)₃₄(SiO₂)₆₆]/[ZnO]}_n multilayer structures, where n = 50 is the number of bilayers (Co₄₀Fe₄₀B₂₀)₃₄(SiO₂)₆₆ nanocomposite and ZnO have been studied. The thicknesses of (Co₄₀Fe₄₀B₂₀)₃₄(SiO₂)₆₆ nanocomposite layers as well as ZnO spacers were varied in a wide range. The samples were synthesized by ion-beam sputtering onto glass ceramic substrates. The (Co₄₀Fe₄₀B₂₀)₃₄(SiO₂)₆₆ composite have an amorphous structure and the semiconductor ZnO interlayers have a hexagonal crystalline structure with the p63mc symmetry group. The nanocomposite layers containing a ferromagnetic component far from the percolation threshold are in a superparamagnetic state. The presented in the paper data of magnetization, magneto-optical transverse Kerr effect and magnetoresistance indicates that long-range ferromagnetic order does not form down to 77 K both for references ZnO films and studied multilayers with thin and thick ZnO interlayers. An increase in the magneto-optical signal in multilayers compared to references (Co₄₀Fe₄₀B₂₀)₃₄(SiO₂)₆₆ composite films has been detected at 1.2 eV. The magnetoresistance of {[(Co₄₀Fe₄₀B₂₀)₃₄(SiO₂)₆₆]/[ZnO]}_n multilayers with thick (>32 nm) ZnO interlayers is lower than in reference (Co₄₀Fe₄₀B₂₀)₃₄(SiO₂)₆₆ nanocomposite, while at thin ZnO interlayers magnetoresistance is significantly higher and reaches 12 % at temperatures of 77 К. Possible mechanisms of ferromagnetic and antiferromagnetic ordering, enhancement of the magneto-optical response and magnetoresistance in {[(Co₄₀Fe₄₀B₂₀)₃₄(SiO₂)₆₆]/[ZnO]}_n multilayer nanostructures are discussed.

http://dx.doi.org/10.2139/ssrn.4805398

Ni2CrBO5 has been synthesized and investigated by X-ray diffraction, dc magnetization, and specific heat measurements. The unusual cation distribution has been established: the M1 and M3 sites are occupied by Ni2+ ions, the M2 site is by Cr3+ ions, and the M4 site is mixed, featuring both Ni2+and Cr3+ ions. The magnetic order onsets at TN=140 K, which is confirmed by a λ-type peak in specific heat, followed by the dome-shaped anomaly of the magnetization at about 30 K. In the magnetically ordered state, a remarkable sequence of temperature-induced magnetization reversal sensitive to the measurement’s regime is observed. Dominant antiferromagnetic interactions are characterized by the Weiss temperature θ = -73 K. The effective magnetic moment of 5.37 μB per formula unit is close to the spin-only one. The effect of the cation distribution on the magnetic properties is discussed.

https://doi.org/10.1016/j.jssc.2024.124880

Lanthanum selenidofluorides belong to wide-gap semiconductors and are promising for optoelectronics. La₂F₄Se, B–LaFSe compounds were obtained by the ampoule method from binary compounds. Crystals La₂F₄Se, R-3m, a = 4.18245(11) Å, c = 23.2939(6) Å, Z = 3, B–LaFSe P6₃/mmc, a = 4.21989(5) Å, c = 8.19140(10) Å, Z = 2 have a layered grain structure, their microhardnesses are 340 and 450 HV, which allows samples processing. The optical bandgap of La₂F₄Se is 4.5 eV. The optical bandgaps of La₂F₄Se and B–LaFSe were analyzed by comparing the calculated absorption spectra and the experimental Kubelka-Munk Functions. It was shown that this approach is attractive in explaining optical properties in the vicinity of fundamental absorption onset and in neighboring regions. In LaF₃–La₂Se₃ system, temperatures and enthalpies of five phase transformations were determined, and their balance equations were obtained. It was shown that La₂F₄Se, B–LaFSe compounds melt incongruently and that an eutectic is formed between the phases. A phase diagram of LaF₃–La₂Se₃ system was constructed. The liquidus calculated by Redlich-Kister polynomial agrees with the data of differential scanning calorimetry.

https://doi.org/10.1016/j.jallcom.2024.175500

The kinetics of diffusion and formation of Al-Au intermetallic compounds in a solid-state reaction between layers of aluminum and gold has been studied by the method of in situ electron diffraction. The phase sequence in the solid-state reaction in Al/Au thin films is found to depend on the atomic ratio of aluminum and gold at the initial state. Specifically, with the atomic ratio being Al:Au=2:1, one observes the formation sequence: Al₃Au₈→AlAu₂→Al₂Au, while with the ratio Al:Au=1:4, the sequence is Al₃Au₈→AlAu₄. The observed change in the sequence is explained using the theoretical model of EHF (Effective Heat of Formation). The kinetic parameters of the diffusion of gold through the layer of reaction products in the Al/Au thin films have been determined, including the apparent activation energy of the diffusion E_a=1.17 eV and pre-exponential factor D₀=120 cm²/s. Based on the data obtained by in situ electron diffraction, the kinetic parameters of the phase formation have been estimated by the Kissinger-Akahira-Sunose method. In addition, the kinetic parameters of the formation of the Al-Au intermetallic compounds have been determined (apparent activation energy E_a, pre-exponential factor A) in the solid-state reaction in the Al/Au thin films, namely, E_a = 0.77 eV, log(A, s⁻¹) = 9 for Al₃Au₈; E_a = 1.08 eV, log(A, s⁻¹) = 13 for AlAu₂; E_a = 1.13 eV, log(A, s⁻¹) = 13 for Al₂Au; and E_a = 1.35 eV, log(A, s⁻¹) = 16 for the phase AlAu₄. The kinetic parameters of the formation of the AlAu₄ phase have been estimated for the first time.

Liquid crystal cells, in which the planar director orientation is specified by SU-8 polymer films treated by the stamp nanoprinting method, have been studied. The orienting film surface after texturing represents a comb-shaped lattice, the profile of which depends on the processing temperature. In cells filled with nematic LC E7, a homogeneous orientational structure with a small number of surface linear defects on both substrates is formed. These defects do not appear in LC cells with asymmetric substrates, when one of them is coated with an SU-8 film, and the other one is covered with a rubbed nylon-6 film. It has been shown that the director pre-tilt angle on the studied SU-8 films is close to zero and the films set a strong polar anchoring energy for the nematic E7. The results obtained are of interest for the development of methods for manufacturing LC devices using technologies for nanoprinting of orienting polymer films.

DOI: 10.18083/LCAppl.2024.1.90

Исследовано фотоиндуцированное изменение ориентационной структуры хирального нематика на основе ЛН-396, допированного хиральными добавками S811 и cChD. Продемонстрировано, что использование планарно-конических граничных условий позволяет реализовать плавное изменение угла закрутки его структуры вследствие изменения шага спирали. Показано, что при коническом сцеплении, задаваемом полимером ПиБМА для исследуемого хирального нематика, закрутка структуры на угол более 240° приводит к появлению ондуляций структуры. Обнаружено, что полимер ПтБМА задает для исследуемого хирального нематика тангенциальные граничные условия, позволяющие директору легко поворачиваться в плоскости образца. Представленные результаты могут быть перспективными для разработки жидкокристаллических систем с тонко настраиваемыми и перестраиваемыми полярным и азимутальным углами директора.

DOI:10.18083/LCAppl.2024.2.54

In order to gain an adequate understanding about the nature of spectral and optical properties of uniaxial molecular (polymer) films, the data about the energy structure of molecules (monomers) and the long-range orientation order of dipole moments m_q of electronic/vibrational transitions are needed. This order is characterized by the order parameters U_q of moments m_q with respect to the optical axis n of the film. Until now, components n_j(omega), k_j(omega) of refractive indices N_j(omega) = n_j(omega) – ik_j(omega) or components epsilon_(1,2)j(omega) of dielectric constants epsilon_j(omega) = epsilon_1j(omega) – iepsilon_2j(omega) of the film for the light-wave polarizations along (j = ||) and across (j = perpendicular) the axis n had been used as indirect sources of such data. The direct information about the energy structure of molecules (monomers) and parameters U_q is contained in the components gamma_(1,2)j(omega) of ensemble-averaged polarizabilities gamma_j(omega) = gamma_1j(omega) – igamma_2j(omega) of molecules (monomers). In this work, components P_(1,2)j(omega) of polarizabilities densities P_j(omega) = [epsilon_j(omega) – 1]/f_j(omega) = 4PiNgamma_j(omega) = P_1j(omega) – iP_2j(omega) are used for receiving such information. Here, f_j(omega) = 1 + L_j[epsilon_j(omega) – 1] are the local-field tensor components for the light wave in the film; the Lorentz-tensor components L_j are obtained using the dependences n_j(omega) in the transparency region of the film; N is the number of molecules (monomers) per unit volume of the film. Methods for determining parameters U_q for molecular transitions were developed using the dependences P_(1,2)j(omega) within the isolated absorption bands corresponding to the transitions. The methods were confirmed for the uniaxial films of the conjugated polymer F8BT with the preferred orientation of macromolecules in the film plane XY with the optical axis n||Z and the known dependences n_j(omega), k_j(omega) in the transparency and lowfrequency electronic absorption ranges. The spectral-invariant correlations connecting functions P_(1,2)j(omega) and epsilon_(1,2)j(omega) were established.

https://doi.org/10.2174/0113852728296495240409062733

Synthesis of new hybrid organosilicon compounds based on the amides 1- naphthylacetic acid was described. N-Organyl-2-(1-naphthyl)-N-[(triethoxysilyl)methyl]- acetamides were obtained by the reaction of 1-naphthylacetyl chloride with α-silylamines RNHCH₂Si(OEt)₃ (R = Me, i-Pr and Ph). Their subsequent interaction with N(CH₂CH₂OH)₃ led to the formation of N-organyl-2-(1-naphthyl)-N-(silatranylmethyl)acetamides. The structure of these hybrid compounds was characterized by ¹H, ¹³C, and ²⁹Si NMR spectroscopy. The structure of N-methyl- and N-isopropyl-2-(1-naphthyl)-N-(silatranylmethy)acetamides was confirmed by X-ray diffraction analysis. Results of computational screening showed that these silatranes are bioavailable and have drug-likeness.

DOI 10.1088/1555-6611/ad5156

In experiments on second harmonic (SH) generation (SHG), a conical structure of radiation has been observed. In the present study, a non-stationary theory of SH excitation of ultrashort laser pulses with phase modulation has been developed, which explains the properties of such a structure as Cherenkov radiation. Under phase-mismatched interactions, a maximum of the SH spectrum is observed at the Cherenkov angle, which is determined by the ratio of the SH and laser radiation phase velocities. It is shown that tightly focused laser beams are preferred to observe Cherenkov SHG. The SH spectral width depends on the group velocity mismatch and is more complicated on the excited radiation spectrum. The SH energy can be proportional to the crystal length or group delay length depending on their ratio. We also demonstrate that a complex angular distribution of spectral components (an angular chirp) appears within the SH cross-section.

https://doi.org/10.1016/j.jtice.2024.105560

Crystal structure of rare-earth LaCoO₃ cobalt oxide subjected to high energy mechanical activation has been studied. In the temperature range of 300–800 K, the electrical conductivity and Seebeck coefficient were measured. Thermal conductivity was measured at 300–480 K.

DOI https://doi.org/10.1039/D4AY00706A

Melanoma inhibitory activity protein (MIA) does obviously offer the potential to reveal clinical manifestations of melanoma. Despite a pressing need for effective diagnosis of this highly fatal disease, there are no clinically approved MIA detection ELISA kits available. A recommended MIA threshold has not yet been defined, mostly by reason of variability in immunoglobulins' affinity and stability, the difference in sample preparation and assay conditions. Here we present a pair of high-affinity DNA aptamers developed as an alternative recognition and binding element for MIA detection. Their stability and reproducible synthesis are expected to ensure this analysis under standard conditions. The devised aptamer-based solid-phase microassay of model standard and control human sera involves luciferase NLuc as a highly sensitive reporter. Bioluminescence dependence on MIA concentration ranges in a linear manner from 2.5 to 250 ng mL⁻¹, providing a MIA detection limit of 1.67 ± 0.57 ng mL

https://doi.org/10.1007/s10909-024-03171-5

We study different resonances (first of all of the Fano type) in the interference device formed by the Aharonov–Bohm ring with superconducting (SC) wire in the topologically nontrivial state playing a role of a bridge between top and bottom arms. We analyze Majorana modes on the ends of the SC wire and show that the collapse of the additional Fano resonance, that is initially induced by transport scheme asymmetry, is connected with the increase of the length of the bridge when the binding energy of the Majorana end modes tends to zero. In local transport regime, the Fano resonances are stable against the change of the transport symmetry. The reasons of both collapse and sustainability are analyzed using a spinless toy model including the Kitaev chain.

https://doi.org/10.1007/s10853-024-09885-x

The effect of the size of Bi₂Fe₄O₉ and BiFeO₃ nanoparticles on the magnetoelectric interaction in the Bi₂Fe₄O₉/BiFeO₃ composite with a percentage ratio of 67/33 has been studied. The electrostriction and electric polarization on electric and magnetic field in wide temperature range has been measured. The hysteresis of the polarization and I‒V characteristics has been found. Temperature ranges with activation and hopping types of conductivity have been found. The mechanism of electric polarization and the crossover temperature from dipole polarization to migration polarization at 260 K have been established. Linear and quadratic contributions to the magnetoelectric effect have been found. Below 120 K the linear contribution is an order of magnitude greater than the quadratic contribution and above 240 K the quadratic contribution to the ME effect prevails. Models have been proposed to explain the enhancement of the magnetoelectric effect as a result of the migration polarization in mullite and linear magnetoelectric effect in bismuth ferrite. The correlation of temperatures of the extremum of the temperature coefficient of the electrical resistance and the magnetic phase transition in mullite at 260 K indicates a polaron-type conductivity and a strong electron‒phonon interaction. A change in the sign of the electrostriction coefficient upon heating and the compression temperature of the composite in an electric field was found.

https://doi.org/10.1016/j.ceramint.2024.06.171

The Mn_XTm_1‒XSe (0 ≤ Х ≤ 0.2) solid solutions have been first synthesized and their structural, magnetic, and transport properties have been studied in the temperature range of 80–1000 K and magnetic fields of up to 12 kOe. The surface morphology of the samples has been examined and the chemical analysis has been carried out. It is shown that the valence change with the increasing substitution concentration is accompanied by a change in the lattice parameter and a decrease in the magnetic moment of the samples. The Kondo temperatures caused by the manganese and thulium subsystem have been found in the low- and room-temperature regions. The temperature of localization of small-radius polarons has been determined. A drastic decrease in the relaxation time in the range of the manganese ion percolation through the lattice in the Mn_XTm_1‒XSe system has been established. The change of the current carrier type upon variation in the temperature and substitution concentration was determined from the Seebeck coefficient. A high-temperature extremum of thermopower was revealed, which is explained within the framework of the Anderson model.

https://doi.org/10.1016/j.vacuum.2024.113375

The controlled vacuum-arc synthesis of zirconium dioxide (ZrO₂) nanoparticles is considered, which makes it possible to regulate the percentage ratio of the monoclinic and tetragonal phases. The samples were characterized using XRD analysis, SEM, HRTEM analysis, FT-IR analysis, TG/DTA analysis and EPR spectroscopy. It has been established that the formation of the tetragonal phase is associated with the formation of a large number of oxygen vacancies formed due to high-speed quenching of nanoparticles. Reducing the operating gas pressure in a vacuum chamber from 180 Pa to 30 Pa makes it possible to obtain nanoparticles up to 2 nm in size. The synthesized ZrO₂ nanoparticles do not contain foreign impurities and when heated, the weight loss is up to 7 %. The process of local resistive switching in the contact of an atomic force microscope (AFM) probe to a nanostructured ZrO_(2-x) layer on a conducting substrate has been studied. Cyclic current-voltage characteristics demonstrate the existence of stable states of high and low resistance, switched by changing the polarity of the applied voltage. The coexistence of the m- and t-ZrO₂ phases (and the resulting oxygen nonstoichiometry in the interboundary regions) provides conditions for the formation/destruction of a filament from oxygen vacancies, which determine the conductivity of the dielectric in the LRS state

https://doi.org/10.1002/adfm.202401860

Hybrid metal halides (HMHs) have emerged as a promising platform for optically functional crystalline materials, but it is extremely challenging to thoroughly elucidate the electron transition coupled to additional ligand emission. Herein, to discover sequences of lead-free HMHs with distinct optically active metal cations are aimed, that is, Sb³⁺ (5s²) with the lone-pair electron configuration and In³⁺ (4d¹⁰) with the fully-filled electron configuration. (Me₂NH₂)₄MCl₆·Cl (Me = −CH₃, M = Sb, In) exhibits the superior temperature/component-dependent luminescence behaviors resulting from the competition transition between triplet-states (T_n-S₀) self-trapped excitons (STEs) of inorganic units and singlet-state (S₁-S₀) of organic cations, which is manipulated by the optical activity levels of [SbCl₆]³⁻ and [InCl₆]³⁻. The bonding differences between Sb³⁺/In³⁺ and Cl⁻ in terms of electronic excitation and hybridization are emphasized, and the different electron-transition mechanisms are established according to the PL spectra at the extreme temperature of 5 to 305 K and theoretical calculations. By fine-tuning the B-site Sb³⁺/In³⁺ alloying, the photoluminescence quantum yield (PLQY = 81.5%) and stability are optimized at 20% alloying of Sb³⁺. This research sheds light on the rules governing PL behaviors of HMHs, as well as exploring the optical-functional application of aviation temperature sensors and access-control systems.

https://doi.org/10.1039/D4TC01477D

The discovery of novel Mn²⁺-based metal halides with excellent luminescence properties and thermostability is particularly of great importance for solid-state lighting (SSL). Herein, a novel one-dimensional hybrid manganese chloride (TMA)MnCl₃ of a hexagonal system with a P6₃/m space group is synthesized via a simple saturation crystallization method. Under 443 nm excitation, (TMA)MnCl₃ single crystals exhibit a strong broad-band red emission peak at 645 nm originating from the ⁴T₁ → ⁶A₁ transition of Mn²⁺ ions with a full width at half maximum of 99 nm and a photoluminescence quantum yield (PLQY) of 98.6%. Moreover, (TMA)MnCl₃ shows a high anti-thermal quenching behavior, and the integrated PL intensity still retains 100% of the initial intensity measured at 300 °C, caused by the high structural rigidity. Benefiting from its strong blue light excitation, high PLQY, and excellent thermal stability, a stable white light-emitting diode device is fabricated by combining a 465 nm blue LED chip, green-emitting Lu₃Al₅O₁₂:Ce³⁺ and the (TMA)MnCl₃ red phosphor with a high color rendering index of 94.3% and a correlated color temperature of 3995 K. This work develops a novel hybrid manganese chloride red-emitter and paves a new path to explore high-performance phosphors excited by blue light for SSL.

https://doi.org/10.1016/j.jallcom.2024.175104

Hydrated iron fluoridotitanate (FeTiF₆ × 6 H₂O) single crystals are fascinating magnetic materials with unique properties. To understand the underlying mechanisms, this study combines X-ray absorption near-edge structure (XANES) and X-ray magnetic circular dichroism (XMCD) techniques, complemented by density functional theory (DFT) calculations. Polarization-dependent X-ray absorption spectroscopy, encompassing XANES and XMCD, is a powerful technique for probing the local structures and magnetic properties of materials. It is element-selective, bulk-sensitive, and compatible with a wide range of experimental conditions. In this study, we used XANES and XMCD spectroscopies to investigate the local structures and magnetic properties of Fe and Ti in FeTiF₆ × 6 H₂O single crystals. XANES analysis revealed distinct local environments around Fe and Ti, providing insights into their coordination environments. Element-selective magnetization measurement at the Fe K-edge demonstrated that iron sites in the oxidation state Fe²⁺ have an unambiguous paramagnetic contribution to the magnetization along the b-axis. Notably, the absence of an XMCD signal at the Ti K-edge confirmed the absence of a magnetic moment in Ti atoms within the crystal. DFT calculations corroborate the experimental findings and provide insights into the electronic structure and magnetic interactions. The combined results provide a comprehensive understanding of the dynamic Jahn-Teller effect in FeTiF₆ × 6 H₂O single crystals, highlighting the significance of polarization-dependent X-ray absorption spectroscopy in unraveling the intricate magnetic behavior of such materials. This study contributes to the fundamental understanding of magnetism in these materials and paves the way for the development of novel magnetic materials with tailored properties.

https://elib.sfu-kras.ru/handle/2311/152806

Controlled drug delivery is one of the frontier areas of science, which uses an interdisciplinary approach. The delivery systems offer numerous advantages over conventional dosage forms, such as improved efficacy and patient compatibility, reduced toxicity, and ease of use. Such systems often use micro- and nanoparticles as carriers for drugs, the prolonged effect of which is achieved due to the controlled slow release of the encapsulated drug. This study investigated the effects of encapsulation of various antiseptics (brilliant green, miramistin, and furacilin) and the chemical composition of the polymer on the yield, structure, size, drug release kinetics, and antibacterial activity of microparticles produced from resorbable polyesters of microbiological origin, polyhydroxyalkanoates. Microparticles with a 5.6–94.8 μm diameter were produced. The form of the active substance molecule has been found to be the most significant factor affecting the characteristics of polyhydroxyalkanoate microparticles. The surface structure of particles is rather determined by the chemical composition of the polymer, and the release kinetics to the model medium depends on the encapsulated drug. Microparticles based on PHAs loaded with brilliant green and furacilin showed antibacterial effects in S. aureus and E. coli cultures. The study demonstrated that microparticles with antiseptics encapsulated in them have potential as prolonged drug delivery systems and are of interest for further research

https://doi.org/10.1007/s10853-024-09755-6

Mn₅Ge₃ is a ferromagnetic hexagonal crystal promising for spintronics and magnetocalorics. A systematic study and analysis of the magnetic properties of the Mn₅Ge₃ thin film grown on Si(111) were performed. The magnetic anisotropy of the film is determined by the shape anisotropy and the easy magnetization axis aligned along the c axis of the crystal. The uniaxial anisotropy constant K_u fully corresponds to that for a bulk single crystal, which indicates that c axis coincides with film normal. Mn₅Ge₃ film demonstrates high saturation magnetization M_S = 900 emu/cm³ (900 kA/m) at T = 100 K and magnetocaloric effect ΔS = 3.16 ± 0.22 J kg⁻¹ K⁻¹ at 300 K and B = 1.5 T. ΔS is comparable to that for multicomponent or Gd rare earth films. Furthermore, a different anisotropy of the magnetocaloric effect compared to bulk Mn₅Ge₃ was found, which may be related to the anisotropy of the film shape and, possibly, to the domain structure. The results obtained are promising for the design and development of magnetocaloric, spintronic, and spin-caloritronic devices on a silicon platform.

https://doi.org/10.1016/j.matchemphys.2024.129524

Magnetic nanocomposites containing iron oxide and gold components take great attention last years because of their relative biocompatibility and the ability to combine the magnetic properties of iron and the chemical bonding properties of gold for the possible drug delivery or diagnostics for various diseases. However, such particles have some toxicity to living cells, and the effect depends on many factors, including size, shape, the ratio of components in the composites, and the type of cells affected. And thus, the search for compositions and technologies for producing iron-gold particles with improved properties and reduced cytotoxicity remains relevant. The aim of the study was to synthesize and characterize Fe₃O₄/Au nanocomposites and evaluate their influence on living cells using the example of cell line HEK293.

Fe₃O₄ nanoparticles (NPs) were synthesized by co-precipitation of Fe²⁺/Fe³⁺ water solution in alkaline conditions and then boiled with HAuCl₄ in 0.1 M sodium citrate. The NPs properties were estimated by transmission electron microscopy (TEM), vibration magnetometry and ferromagnetic resonance (FMR).

According to magnetometric measurements, nanoparticles are mainly in a superparamagnetic state. By fitting magnetization curves, the magnetic characteristics of nanoparticles were determined: saturation magnetization (59.3 emu/g) and magnetic anisotropy constant (� = 0.86·10⁵ erg/cm³). The average particle size estimated from magnetic measurements was 8.7 nm. Considering the presence of a magnetically dead layer, this is in good agreement with the TEM results. The temperature dependence of the FMR linewidth was analyzed using two models. As a result, the parameters ��� and �/�� were determined. The models used showed good agreement. The values of the anisotropy constant (� = 1.06·10⁵ erg/cm³) and the average particle size (6.8 nm) are estimated.

The effect of the NPs on the HEK293 cells was studied by MTT-assay, flow cytometry and RT-PCR. The exposure with the NPs lead to a significant decrease of cell metabolic activity in HEK293 cell culture, but this effect was not accompanied by cell death. It was shown that the expression of antioxidant enzymes SOD1 and GPX1 was reduced at the mRNA stage. So the NPs synthesized may affect gene expression and metabolism of HEK293 cells, but this does not have fatal consequences for cell viability.

https://doi.org/10.48550/arXiv.2404.14726

The levitation of a cylindrical permanent magnet over a high-temperature superconductor cooled by liquid nitrogen can be accompanied by spontaneous oscillations and rotation. The reason for spontaneous rotation of the magnet is magnetization inhomogeneity induced by the temperature gradient. An experiment was carried out on the levitation of Nd-Fe-B magnets over a composite high-temperature superconductor. The experimental results confirm that the rotation frequency depends on the difference in the magnetization values in the upper and lower halves of the magnet. Methods for controlling the rotation frequency of a levitating magnet are proposed.

https://doi.org/10.1007/978-981-99-6105-4_22

People have been exposed to airborne nanosized materials (100 nm) for thousands of years, but since the industrial revolution, particularly with regard to combustion operations, the level of exposure has significantly increased. Since the advent of nanotechnology, two decades ago, the danger of exposure to nanomaterials by ingestion, absorption through the skin, absorption through the dermis, and medication administration utilizing designed nanoparticles, has grown. Nanomaterials acquire new mechanical, electrical, optical, catalytic, and, last but not least, biological capabilities when they shrink from bulk to nanoscale. The creation, usage, and disposal of the product, as well as the toxicological impacts of nanomaterials, must all be studied. Basic multidisciplinary research including materials scientists, toxicologists, medical professionals, and environmental engineers is necessary to better understand the health risks and safety concerns of nanoparticles.

https://doi.org/10.1134/S0361768824010067

wolfram cellular automata are considered and their operation is demonstrated using an example of traffic flow simulation. For the class of one-dimensional elementary cellular automata, the concept of linearity is introduced in the language of Zhegalkin operators. An algorithm for finding linear Zhegalkin operators with multipliers of three variables is presented. The algorithm is implemented in Python.

https://doi.org/10.1134/S1062873824706573

The authors propose a way of reconstructing the Raman tensor by studying the angular dependences of the intensities of the Raman lines of unoriented microcrystals. The technique is verified using familiar calomel Hg₂Cl₂ crystals. It is shown that the lines on DUT-8 (Ni) crystals indicating phases with open and closed pores have different types of symmetries. The technique can be used to reconstruct the Raman tensor for any unoriented crystalline sample.

https://doi.org/10.1016/j.jtice.2024.105560

Crystal structure of rare-earth LaCoO₃ cobalt oxide subjected to high energy mechanical activation has been studied. In the temperature range of 300–800 K, the electrical conductivity and Seebeck coefficient were measured. Thermal conductivity was measured at 300–480 K.

https://doi.org/10.1134/S0030400X24700206

Using a generalized refractive mixture dielectric model, the influence of the relative permittivity spectra of bound and unbound water in mineral soil on the nature of the temperature dependence of the relative permittivity of natural mineral soil, with a clay fraction content of 41.3%, was studied in the electromagnetic field frequency range from 50 MHz to 15 GHz. The causes of the emergence of intersections in the relative permittivity spectra of mineral soil, obtained at different temperatures but for a sample of the same moisture content, have been studied. It has been proved that the emergence of such an intersection point in the frequency range up to 1.5 GHz is due to the Maxwell–Wagner effect in bound water. The dependences of the frequency of the intersection point of the relative permittivity spectra of mineral soil on the temperature and volumetric content of bound and unbound water have been studied.

https://doi.org/10.1016/j.jmmm.2024.172193

The magnetic properties of ordered MAX phases Mn₂(Al_xGa_1−x)C (x = 0.125, 0.25, 0.5, 0.75 and 0.875) have been studied within the DFT-GGA. We have found that increase of Al atom at A-site leads to the formation of the ferromagnetic phase with large magnetization of about 3.6 μ_B/f.u. The investigation of the phase stability is performed by comparing the total energy of the MAX phases with that of a set of competitive phases for calculation of the phase formation enthalpy. Up to a concentration of Al atoms x = 0.7 the compound remains thermodynamically stable. The exchange constants analysis shows the crucial role of exchange interactions between manganese atoms along the c-axis in forming of ferromagnetism. The magnetic transition temperature of Mn₂(Al_xGa_1−x)C alloys increases with increase of the aluminum concentration.