P.N. Lebedev Physical Institute of the Russian Academy of Sciences

The reactions of copper(II) and zinc(II) salts with 2-{[(4H-1,2,4-triazol-4-yl)imino]-methyl}phenol (HL) were studied. The reaction of copper(ii) trifluoroacetate with HL in MeOH affords the mononuclear complex [CuL2] (1). In the crystal, molecules 1 form a supramolecular layered structure through Cu⋯N contacts (2.74 Å). The reaction of zinc(ii) chloride with HL in the presence of Et3N gives the 2D coordination polymer [ZnL2]n (2), whereas this reaction using a protonating agent (HCl) instead of the organic base produces the mononuclear complex [Zn(HL)2Cl2] (3). The photoluminescent properties of compounds HL, 2, and 3 were studied and their 1H NMR spectra were measured. The electronic absorption spectra of all synthesized compounds in solution were recorded. The free ligand HL and compounds 1–3 were evaluated for antibacterial activity against E. coli and S. aureus strains, antifungal activity against the molds A. fumigatus, R. oryzae and the yeast fungi C. albicans, C. glabrata, and antiprotozoal activity against Colpoda steinii.

It has been demonstrated experimentally and in the theoretical calculation that the energy of protons accelerated by a 60-TW femtosecond laser pulse can be increased by choosing the optimal position of the focus spot relative to the surface of the irradiated target at a given nanosecond pedestal due to amplified spontaneous emission. This position is determined as the best focusing option that ensures a sufficiently efficient matching of incident and preplasma-trapped laser radiation under the conditions of emerging self-consistent spatial profiles of the preplasma and crater (i.e., the remaining thickness of the target) on the irradiated surface. At the same time, the focal spot does not lie on the surface of the target, but is shifted into the preplasma, which makes it possible to raise the maximum proton energy by a factor of 1.5.

Optical microscopy studies have demonstrated that the chemical composition of the Li2O–Nb2O5–Tb2O3 melt has a significant effect on the macro- and microdomain configuration of the growth defect structure in the bulk of the nonlinear optical LiNbO3 single crystal doped with subthreshold concentrations of the Tb³⁺ ions, which is promising as an active nonlinear laser medium for continuous-wave generation in the blue spectral range. In the frequency range of 1000–2000 cm⁻¹, second-order Raman lines were detected in LiNbO3:Tb³⁺(0.1, 0.48, 2.21 wt%) crystals, the intensity and frequencies of which depend on the concentration of the Tb³⁺ ions. These lines are interpreted as manifestations of bound states of fundamental optical vibrations formed as a result of strong anharmonicity of vibrations and the presence of various types of structural defects in the crystal. It is shown that the presence of lines with frequencies of 3470, 3483, and 3486 cm⁻¹ in the IR absorption spectra of LiNbO3:Tb³⁺(0.1, 0.48, 2.21 wt%) crystals in the region of OH-group stretching vibrations is due to the violation of the stoichiometry (Li/Nb values) of the crystal and the formation of complex defects (VLi-OH). It is established that in the studied LiNbO3:Tb³⁺ crystals, there are two times fewer VLi point defects than in the congruent LiNbO3 crystal.

The cascade relaxation of a polarized vacuum in the expanding Universe is a chain of evolutionary epochs of decreasing its density with the exit of dominant fields (each in its own time) from the initial zero states to nonzero values, from the dominant scalar field in the early Universe to subsequent ones, including the Λ-term in the modern Universe. The cascade vacuum relaxation creates the entire observable cosmology from the Friedmann model with small perturbations of the metric with non-power-law power spectra from which primordial black holes could have arisen, and gravitational waves over a wide wavenumber range to the formation of dark matter and energy, early galaxies, supermassive black holes, and the large-scale structure of the Universe. An observational model of cascade vacuum relaxation in the early Universe has been constructed, which contains two constants determined by observational data and does not require information on the potential of the fields. A solution has been obtained for the general relativity vacuum attractor, including, in addition to the two previously mentioned constants, the third constant (not yet limited by observations), which leads to an additional power of density perturbations on a small scale ( k > 10 Mpc –1 ) in the form of a “bump,” a two-power spectrum, etc.

For the first time, the Raman spectra in a range of 50–2850 cm ⁻¹ from different areas of the gradient crystal LiNbO 3 :Er ³⁺ (congruent in the main components, Er gradient of 0.55 at%/cm) grown by the Czochralski method were investigated. The compositionally homogeneous, nominally pure, congruent LiNbO 3cong ( R = [Li]/[Nb] = 0.946) and the single‐crystal LiNbO 3 :Er ³⁺ (3.1 wt%), also grown by the Czochralski method, were used as reference samples. It was found that in the gradient crystal LiNbO 3 :Er ³⁺ (congruent in the main components, Er gradient of 0.55 at%/cm), the intensity of the second‐order Raman lines is significantly higher than the intensity of fundamental vibrations, which is due to the high microheterogeneity of the gradient crystal. A coincidence of the type of Raman spectra in scattering geometries and has been established, for which no explanation has been found at the moment. It has been shown that second‐order Raman spectra can be a powerful tool for studying the compositional and structural perfection of materials based on LiNbO 3 crystals, including doped crystalline and ceramic materials and materials with an artificially specified composition gradient.

Introduction. The development of methods for early diagnosis of tumor diseases of the head and neck is one of the most important areas of biomedicine and healthcare in general. Special attention should be paid to consideration of issues related to the diagnosis of malignant neoplasms of the skin of the head and neck area. In this aspect, confocal Raman microspectroscopy is of interest. Objective. To demonstrate the feasibility of using Raman microspectroscopy to differentiate intact skin from malignant skin neoplasms. Material and methods. The study used Raman microspectroscopy with an excitation wavelength of 532 nm to diagnose basal cell carcinoma and squamous cell carcinoma of the skin and differentiate them from intact skin. Results. During the study, spectra of intact skin and skin neoplasms in the head and neck region (basal cell and squamous cell carcinoma of the skin) were obtained. Conclusion. The results of the study can be used in the future for optical biopsy and early diagnosis of tumors.

An Erratum to this paper has been published: https://doi.org/10.1134/S1062873825020017

In this paper, we theoretically study how electron scattering on domain walls modifies the anomalous transverse conductivity on the surface of a magnetic semiconductor with a strong Rashba effect. The band structure of such a semiconductor, characterized by a nontrivial Berry curvature, determines the occurrence of a one-dimensional resonant state on the magnetic domain wall in a local exchange gap. Under relatively weak exchange splitting, the resonant state has linear dispersion with small spectral broadening and has the property of chirality. It is shown that the presence of a pair of parallel domain walls on the surface can have a measurable physical consequence: an additional almost half-quantized contribution to the anomalous Hall effect. The surface of the BiTeI polar semiconductor doped with transition metal atoms is a suitable material platform for detecting such a contribution.

Through numerical experiments, we have predicted that if dark matter contains even a small fraction, ${{f}_{0}} \sim {{10}^{{ - 4}}}$ , of primordial black holes (PBHs), during the formation of the gravitationally bound halo of a dwarf galaxy, these PBHs will concentrate in a region with a radius of about 10 pc, so that their local fraction will exceed 1%. Unlike previous studies of PBH migration to the centers of galaxies, the numerical experiments conducted here take into account the early formation of a massive “dress” of dark matter around the PBHs and the non-stationarity of the halo during its formation. Applying our results to models of heating stellar clusters in the Eridanus II and Segue I galaxies due to dynamical friction between stars and PBHs allows us to impose constraints on the abundance of PBHs that are two orders of magnitude stricter than previously thought.