Vol 83, No 12 (2019)

The formation of annular light bullets during the filamentation of femtosecond optical vortices in a LiF crystal under conditions of anomalous group velocity dispersion is considered. Features of the spatiotemporal dynamics of pulses are described. Quantitative estimates of the parameters of light bullets are given. The mechanism of the formation of a light bullet in the first nonlinear focus is analyzed. Models of a stationary optical vortex and a slit beam are considered.

A way of improving the energy efficiency of diffraction optical elements (DOEs) that form two-lobe light fields whose intensity distribution rotates in propagation is studied. Such DOEs find application in ultrahigh resolution microscopy to modify the spread function of a point light source via phase spatial light beam modulation, allowing all three spatial coordinates of point emitting objects to be reconstructed with nanometric accuracy. Enhancing the energy efficiency of diffraction optical elements is essential for improving the accuracy of point emitter localization in the longitudinal direction (along the Z-axis).

A study is made of the technological processes involved in manufacturing tapered fibers with consistent replicability of parameters when they are heated with a brief non-adiabatic window of narrowing. The results are presented from experiments on the electric-spark manufacturing of tapered fibers with specified parameters on a setup with specialized capabilities for implementing these processes.

Spectroscopic data are presented for the motion of molecules in a liquid during double-pulse excitation and registration of the ultrafast optical Kerr effect (OKE). It is shown that selective spectroscopy of individual molecular motions can be achieved by choosing certain parameters of the double-pulse sequence.

A new approach to the creation of photostable highly sensitive sensor elements for reusable luminescent thermometers based on vitrified films of mesogenic europium(III) and terbium(III) beta-diketonate complexes that are oxygen insensitive, effectively absorbing light in the region of 390–410 nm and reversibly changing the luminescence decay time in the region of 143–348 K, is proposed.

YVO₄:Yb,Er luminescent nanoparticles (NPs) with sizes of 10–700 nm are produced. The use of laser excitation wavelengths of 980 and 257 nm results in the emission of Er³⁺ ions in the spectral region of 527 and 555 nm. No spectral line of Er³⁺ ions is recorded at 660 nm, which is indirect evidence of the low efficiency of nonradiative multiphonon intra-ion transitions and the insensitivity of NPs to luminescence quenchers in an aqueous solution.

A complex procedure is developed that allows remote measuring of a set of characteristics of partial discharges and increased gradients of an electric field at the working voltage. Simultaneous use of electromagnetic, acoustic and electro-optical sensors makes it possible to determine the types and locations of defects and their influence on the workability of high-voltage insulators.

Materials for human torso phantom are selected for testing software in developing systems of intra-operational navigation based on 3D modeling with the technology of augmented reality. According to the Hounsfield scale, the X-ray density of the selected equivalent tissues lies in the range corresponding to certain groups of biological tissues. The reliability of the investigation is demonstrated by comparing 3D models of a real patient and a phantom made from the given material.

The technology for producing metallized coatings on superporous carbon fiber materials from colloidal solutions by means of electrophoresis is studied. Technologies and equipment for the deposition of silver nanoparticles and other metal nanoparticles on rolled carbon materials are considered. The carbon materials consist of fibers 6 μm thick and are used as an electrode materials for current sources.

The relationships between the main parameters of active nanoobjects (nanoparticles, atomic defects, and neutrinos), the Higgs boson, and the Higgs field are studied in the context of models of fractal cosmology. The properties of active nanoobjects depend on pressure, the state of the physical vacuum, and cosmological parameters. Estimates are obtained for the rest masses of neutrinos, and for the limit rotational frequency and size of a nanoparticle in a circularly polarized laser field.

The electric field-induced magnetic inhomogeneities generation is demonstrated in (BiLu)₃(FeGa)₅O₁₂ iron garnet film grown on (110) Gd₃Ga₅O₁₂ substrate. The typical shapes of the generated structures are presented.

An experimental study is performed of the effect constant and pulsed magnetic fields have on the coefficient of diffusion for Sn in α-Fe in the 39.8–557.2 kА m⁻¹ range of magnetic field intensities and 1‒21 Hz range of frequencies at 730°С. It is found that the pulsed magnetic fields have a considerable effect on the coefficient of diffusion for Sn in α-Fe. Resonant behavior of the coefficient of bulk diffusion at pulsed magnetic field intensities of more than 238.8 kА m⁻¹ is observed. Possible mechanisms of the observed effect are discussed.

The model of the response of the microstructure of modified wood on the action of a pulsed magnetic field is proposed. The experimental dependence of the hardness of modified wood on the time of the exposure underlies the model. The model makes it possible to determine the parameters characterizing the kinetics of the formation of intermolecular chemical bonds from free radicals stimulated by the action of a pulsed magnetic field.

The article presents the results of the analysis of changes in the IR-spectra of wood samples after their moistening. The analysis is carried out by a simulation method based on minimizing the standard deviation of the strip profile using the Gauss function. Using the proposed approach makes it possible to specify the mechanisms of moisture transfer in micro pores of wood.

Studies of collisions between ultrarelativistic heavy nuclei at the Relativistic Heavy Ion Collider (RHIC) led to the discovery of a qualitatively new state of matter (strongly coupled quark–gluon plasma), in which quarks and gluons are not bound inside hadrons, but move freely within the volume of the created medium. The U + U collision system with an energy of 192 GeV at the RHIC is the heaviest system of colliding nuclei used in colliding beam experiments and allows us to obtain the highest energy density among systems of ultrarelativistic colliding nuclei. The results are presented from measuring factors of the nuclear modification of π⁰- and η-mesons in (U + U) collisions at an energy of 192 GeV.