Vol 126, No 6 (2019)

Analytical expressions for spontaneous and induced by blackbody radiation energy shifts and widths of atomic circular states are derived. The features of asymptotic behavior of the total width and energy shifts for highly excited Rydberg circular states in the blackbody radiation field are described. Approximate equations are proposed for simple evaluations of energy characteristics and an absence of temperature-independent spontaneous contribution to the total energy width in a range of high temperatures and principal quantum numbers is demonstrated.

Using methods of absorption and fluorescence spectroscopy, we show that noncovalent complexes based on a water-soluble fullerene derivative and chlorin e6 dissolved either in water or in ethanol are formed as a result of electrostatic interactions. The formation of these complexes causes a red shift of the absorption spectrum of chlorin e6 and efficient quenching of the intensity of its fluorescence. The Stern–Volmer quenching constants of complexes in water and ethanol are 7.3 × 10⁵ and 2 × 10⁵ M^–1, respectively. We show that, in an aqueous solution, the complex consists, on average, of one molecule of the water-soluble fullerene derivative and three dye molecules, whereas this ratio in ethanol is 1 : 1.

Light scattering in water and aqueous solutions of NaCl and glucose under the action of a magnetic field with an induction of 0.43 mT is studied. It is established that the magnetic field does not affect the light scattering in water and aqueous solution of NaCl. For an aqueous glucose solution, the switching on of a field leads to the appearance of large fluctuations in the scattering intensity. It has been shown that these fluctuations are due to turbulization of the solution that is caused by the magnetic field.

A fiber laser complex of telecommunication range exhibiting a block architecture the main elements of which are a pulsed erbium fiber laser and several amplification stages is described. Upon inclusion of a fiber element with high normal dispersion, the complex operates as an amplifier delivering high-energy pulses. Characteristic parameters of the power amplifier and parameters of preamplifiers are designed in such a way that the complex can be easily reconfigured into a source of supercontinuum generated in the output highly nonlinear fiber and spanning the range from 600 to 2400 nm.

The problem of second-harmonic generation by a plane elliptically polarized electromagnetic wave from a thin optically nonlinear layer on the surface of a cylindrical dielectric particle of finite dimensions placed in a dielectric medium has been solved analytically in the Rayleigh–Gans–Debye approximation. The result has been presented in the tensor and vector forms in the general case, in which the nonlinear dielectric susceptibility tensor has four independent components (one chiral component and three nonchiral components). It has been shown for the first time that the contribution of chiral components to the generation from the butt-end surfaces of a cylindrical particle differs in phase from the contribution of nonchiral components. It has also been revealed that, if the linear dimensions of a cylindrical particle (height and base radius) are small, the radiation determined by the chiral component of the second-order nonlinear dielectric susceptibility tensor makes a predominant contribution to the second-harmonic generation from a nonlinear cylindrical layer (butt-end and lateral surfaces).

We have presented more than 50 combinations of parameters of the problem on the second-harmonic generation by a plane elliptically polarized electromagnetic wave from a thin optically nonlinear layer on the surface of a cylindrical dielectric particle at which no generation from the lateral surface of the particle is observed. We have also revealed 18 combinations of parameters at which no generation from the butt-end surfaces of the particle is observed. We have determined more than 30 combinations of parameters of the problem at which the second-harmonic radiation generated from the lateral surface (or the butt-end surfaces) of the particle is linearly polarized. Combinations of parameters of the problem have been indicated at which the generation from the entire surface of the cylindrical particle is not observed, as well as parameters at which the polarization of the generated radiation is linear. A method for determining the anisotropy coefficients based on the presented properties has been proposed.

Spectral dependences of complexation in the system of the xylenol orange dye that was immobilized on the surface of ZnO nanoparticles introduced into the volume of hydrogel and lead ions Pb²⁺ have been investigated. It has been shown that the deposition of the dye on the ZnO nanoparticles leads to its binding on the surface and absence of its washing out from the hydrogel, but this process does not prevent the formation of the complexes of the dye with lead ions, which is characterized by increased absorption in the region of 580 nm. The film nanocomposite can be used as a sensor due to its high sensitivity to the presence of low lead concentrations.

Properties of polycrystalline TiO₂ films modified by magnetron sputtering of cobalt followed by pulsed photon-irradiation processing in air are investigated by methods of X-ray phase analysis, raster electron microscopy, atomic force microscopy, magnetic force microscopy, and IR spectroscopy. Formation of a nanocrystalline (with a grain size of ~50 nm) film consisting of cobalt and titanium oxides the surface of which exhibits magnetic properties is established in the process of modification. The IR reflectance spectra obtained at different angles of incidence in the region between 500 and 600 cm^–1 reveal the presence of two bands belonging to transverse modes (TO) and two corresponding bands belonging to the longitudinal modes (LO). These bands are indicative of formation of Co₃О₄ with spinel structure. Investigation of optical absorption suggests a predominant existence of phases characterized by direct interband transitions with energies of 1.43 and 1.83 eV for Co₃O₄, along with a transition with energy of 2.65 eV for cubic phase of CoO, in the films.

The influence of long-term peroral injection of gold nanoparticles with various sizes on the liver, spleen, and lymph nodes of adult laboratory rats and their progeny was studied. The morphometric analysis was conducted using a µVizo-103 medical digital microviser. The conglomerated gold nanoparticles were detected in tissues via the dark-field microscopy. Gold nanoparticles with sizes of 2 and 50 nm were found to cause the mostly pronounced morphological alterations in organs that testifies to their size-dependent impact. The liver in a group receiving 50-nm gold particles exhibit noticeable dystrophy of hepatocytes and activation of a monocyte macrophage system. The spleen and lymph nodes reveal the activation of proliferation and differentiation of immunocompetent cells and macrophages. Peroral injection of gold particles during gestation of females led to an increase in a number of hepatocytes with necrobiotic changes as well as to elevated amount of non-parenchymatic elements in the liver of the progeny, especially in groups containing the 2- and 50-nm gold nanoparticles.

The possibilities of using fluorescence-based analytical methods and their advantages for visualization and identification of the type of programmed cell death in human tumor cells exposed to flavonoids have been analyzed in experiments in vitro. HeLa cervical cancer cells and A498 kidney carcinoma cells were used as the objects of the study, and exposure to the flavonoid-containing extract of common hedgehyssop (Gratiola officinalis L.) was tested as the experimental treatment. The following fluorescence-based techniques were used: the “live and dead” test with double staining by propidium iodide and acridine orange and double staining with annexin and propidium iodide. Autophagy induction was confirmed by fluorescence-based tests implemented in a Muse cell analyzer with a Muse Autophagy LC3-Antibody Based Kit. The use of double staining with acridine orange and propidium iodide fluorescent dyes in the “live and dead” test and comparison with phase contrast microscopy enables the visualization of apoptotic body and autophagosome formation processes in the cells and can, therefore, be used as a method of screening assessment of the efficiency of various chemotherapy drugs.

To diagnose digestive diseases associated with Helicobacter pylori infection, we applied laser spectroscopic analysis of the ¹³СО₂/¹²СО₂ isotope ratio in the exhaled air, which is based on the use of tunable diode lasers. To analyze the isotopic composition of the exhaled air, we developed a spectrophotometer based on a tunable diode laser. The ¹³СО₂/¹²СО₂ ratio was determined using the spectral range near 2.05 μm, in which the R-branch of the 20013–00001 band of ¹²СО₂ overlaps with the P-branch of the 20012–0001 band of ¹³СО₂. H. pylori infection in the gastrointestinal tract of a group of 309 subjects was diagnosed using the ¹³C-urea breath test (¹³C-UBT). The breath test results were compared with the results of morphological analysis of the gastric and duodenal mucosa specimens obtained during fiber gastroduodenoscopy. To compare the results of laser ¹³C-UBT and histology, we have for the first time proposed to use the total values of the results of the histological analysis of biopsy specimens taken in the body and distal part of the stomach and in the duodenum. The dependence of the results of laser ¹³C-UBT on the age, nosology, activity and severity of the inflammatory process, and the degree of atrophy and metaplasia, as well as the type of therapy was analyzed. It is shown that the distribution of the results of laser ¹³C-UBT in patients obtained before and after eradication therapy reflects the epidemiology of gastroduodenal diseases, the incidence of H. pylori infections, the patterns of gastrointestinal tract colonization by H. pylori, the parameters of inflammation, as well as the efficacy of therapy and the characteristics of the recovery of bacterial colonies after unsuccessful therapy.

The possibility to use oral intake of fluorescent dyes approved on humans for intravital fluorescence in vivo imaging is attractive due to its simplicity and non-invasive character. Here we investigate the potential of solid lipid curcumin particles (SLCP) for imaging of capillary permeability using fluorescence video capillaroscopy. Curcumin fluorescence corresponding to 0.7 μg/mL concentration was observed from blood plasma after oral consumption of 2 g of SLCP. However, this signal was ~15% higher than that of blood plasma intrinsic fluorescence, which was itself at least 10-fold lower than the background signal from pericapillary tissue. By comparing the optical properties and concentration to the case of intravenous injection of sodium fluorescein, we analyzed which parameters of the experiment should be optimized for using oral consumption of fluorescing compounds in intravital in vivo capillaroscopy measurements.

We investigated the possibility of using phase-modulation spectrophotometry for the detection and recognition of large blood vessels and nerves in the volume of biological tissues for the tasks of transnasal endoscopic neurosurgery when removing skull base tumors. Optical and dynamic characteristics of neurovascular structures of various types were studied. Informative independent parameters and their corresponding criteria for the detection and recognition of neurovascular structures in the tissue volume, based on the difference in the optical properties of the blood, nerves, and their surrounding tissues, are proposed and experimentally investigated in vivo and in situ. The preliminary results indicate the prospects of applying phase-modulation spectrophotometry in endoscopic neurosurgery and can be used in time-domain spectrophotometry.

The results of an advanced spectral analysis of human donor bone grafts obtained using Raman spectroscopy are presented. Mathematical methods were applied to improve the resolution of spectral profiles, and chemometric principal component analysis was used to evaluate the organic components of the grafts. The results were compared to the proteomic data obtained using mass spectrometry. The main differences between cadaver and intraoperative grafts were observed in the Raman spectral lines at 1450 and 1735 cm^–1 (lipids and fatty acids), 917 and 937 cm^–1 (glycogen), and 814 and 894 cm^–1 (DNA), as well as 1238 and 1560 cm^–1 (amide II and amide III). It is shown that Raman spectroscopy can be employed to evaluate relative concentrations of components of DNA, RNA, collagen, protein, extracellular matrix, and bone tissue.

Mirror and diffuse reflection of light from wheat leaves at two vegetative stages of its development are considered. The research results can serve as a methodological basis for the development of models of optical properties of other crops.