Optics and Spectroscopy最新文献

As a result of the research, the model combining the ResNet-50 architecture and the pre-trained BERT language model that has achieved the following indicators: Accuracy 0.94, AUROC 0.87, and F1‑score 0.90 has been developed.

The aim of this paper is to provide an overview of the current state of graphene magnetoplasmonics, including fundamentals and applications. We consider the physical effects, including the “giant” Faraday effect, in electrically and magnetically controlled graphene magnetoplasmonic metasurfaces, as well as their use for creating new graphene-based plasmonic devices in the THz and IR range that are dynamically tunable by an external magnetic field. We present the principles of operating of electrically and magnetically tunable graphene THz and IR devices: THz absorbers, switches, polarizers, filters, sensors, modulators and integrated magneto-optical elements such as IR isolators and circulators. We discuss their applications in photonics and optoelectronics, telecommunications, THz spectrometry, and biomedical technologies.

Sodium alkylbenzene sulfonates or linear alkylbenzene sulfonates (LAS), as they are commonly known, are among the most toxic anionic synthetic surfactants, which are stable in the freshwater environment. A new approach is proposed to determine these toxicants in natural water in the form of alkylbenzene sulfonic acid methyl esters using high-performance liquid chromatography (HPLC) with spectrophotometric detection in the UV spectral range. The limit of quantification (LOQ) estimated from the peak of the C10 homologue group is 16.0 ng/L under analysis on a Milikhrom™ А-02 chromatograph with a microcolumn 2 × 75 mm in size with a Nucleosil 100-5-С₁₈ sorbent. A new method is proposed for extraction and preconcentration of linear alkylbenzene sulfonates from filtered and ethyl alcohol-preserved water samples, which includes (i) solid-phase extraction on reversed-phase C18 cartridges at a flow rate of 30–50 cm³/min (recovery 100%) with subsequent elution of the analytes with methanol, (ii) re-dissolution of the analytes in distilled water and their re-extraction with chloroform in the form of an ion pair with methylene blue (recovery 98%), (iii) methylation of the extract with a new trimethyl orthoformate reagent in the environmental monitoring with a 98% yield of methyl esters of alkylbenzene sulfonic acids, and (iv) additional precleaning and preconcentration of the analytes by 20 000 times as compared with the initial sample on cartridge tubes with silica gel (100% recovery). The structure of methylated derivatives is confirmed by ¹H NMR spectroscopy and gas chromatography‒mass spectrometry (GC-MS) with electron impact ionization (70 eV) in the total ion current (TIC) mode (m/z 50‒500). The new approaches are tested by analyzing sodium alkylbenzene sulfonate homologues C10–C13 in the water of the Krestovka River, a tributary of Lake Baikal, during spring season when the floods associated with snow and ice melting have already complited by the sampling. The average (n = 3) total concentration of the analytes in river water is estimated as 2.1 ± 0.4 µg/L using the external standard calibration method.

Observation by optical polarization microscopy of test particles (spacers) embedded in a nematic layer with negative diamagnetic susceptibility placed in a magnetic field has shown that there is no movement of particles in the realized torsion geometry. In this regard, a model of magnetohydrodynamic domains describing the motion of a nematic fluid with negative diamagnetic susceptibility in the geometry of splay distortion has been considered.

Modern robotic systems are equipped with complex electrical equipment, which accounts for more than half of the failures caused by degradation processes. Monitoring of the electrical equipment of transport mobile robotic complexes is necessary to warn of the approaching limit. The model of change of the technical condition based on fuzzy inference that allows solving monitoring tasks is discussed. The development of monitoring support based on the considered model will increase the life of transport robotic complexes.

The relevance of the topic is because of the need to master the infrared (IR) range for optical telecommunications systems, IR spectroscopy and biophotonics applications and is dictated by the needs of nonlinear IR optics in the implementation of active optical functions based on graphene, such as IR radiation generation, frequency conversion for applications in optical communications, material processing, precision measurements, spectroscopic sensing, and biological sensors. The purpose of this work is to present the principles of construction and operation of electrically tunable nonlinear devices in the far- and mid-IR ranges: harmonic generators, multipliers, frequency converters, and mixers based on graphene metasurfaces, using the latest achievements of graphene plasmonics.

The paper proposes a method for calculating the ground state of the lithium atom based on the search for the roots of the Jost function calculated for the process of electron scattering by a singly ionized ion.

This article describes the development of a technique for the determination of fat-soluble vitamins using high-performance liquid chromatography with mass spectrometric detection in feed, feed additives. Measurement ranges of mass concentrations of vitamins: A—from 0.35–14.0 mg/kg, D₃—from 0.0065–1.0 mg/kg, and E—from 0.63–50.0 mg/kg. The technique is based on alkaline hydrolysis of the sample and extraction of fat-soluble vitamins with hexane. The analysis of the obtained extracts is carried out by high-performance liquid chromatography with mass spectrometric detection (HPLC MS/MS).

The possibility of complete absorption of an incident electromagnetic wave in a narrow frequency band by a two-dimensional array of metal nanoparticles placed in the surface layer of a one-dimensional photonic crystal structure is demonstrated. The nature of the influence of the parameters of an array of nanoparticles (particle shape, interparticle distance) on the reflection and absorption spectra of the photonic structure in the photonic band gap is determined.

In this work, laser spectroscopy was used to study reverse microemulsions, in which the reaction of ZnS nanoparticle synthesis was carried out. The sizes of the synthesized nanoparticles do not exceed 5 nm. As a result of studying the processes in the reaction medium, it was found that the band of stretching vibrations of HS^– ions in the region of 2568 cm^–1 is an identification sign of the synthesis of nanoparticles: by its intensity it is possible to determine the stage and completion of the ZnS synthesis.