Russian Physics Journal最新文献

This study proposes a novel numerical solution method for the nonlinear one-dimensional Fisher equation, which involves complex and important physical issues concerning the heat conduction and combustion theory. This algorithm adopts a direct meshless technique based on the configuration point method, breaking through the traditional two-level computing framework by introducing combined radial basis functions. The nonlinear Fisher equation with time-varying characteristics can be transformed into a one-level solving problem. Numerical experiments verify advantages of this method in terms of the computational accuracy and efficiency by solving the Fisher equation and modified Fisher equation. Compared to traditional time stepping methods, this one-level solution architecture significantly improves the computational stability with the high solution accuracy.

This work clearly demonstrated a response to changes in glucose concentration via a linear shift of the resonance wavelength with increasing concentration. The photonic crystal-based sensor was constructed using COMSOL based on the finite element method. Furthermore, it was shown that as the radius of the silver rod increased, plasmonic interferences and increased scattering caused the resonance spectrum (FWHM) to broaden and the quality factor to decrease. It was also shown that changing the radius (r₁) of the photonic crystal material had an impact on the maximum transmittance, resonance wavelength, and spectrum width. Research findings showed that the largest detection limit was 2.25·10⁻⁴ RIU, and the best sensitivity was 500 nm/RIU at r₁ = 0.123 μm. GaAs had the shortest spectrum width and best sensitivity, while TiO₂ had the widest spectral range and the highest detection limit. These results suggested that the sensor could be a useful tool for accurately measuring glucose levels.

Some physical and technological conditions for the growth of large GaSe crystals by the Bridgman method and the calculated and experimentally measured parameters of the samples coated with SiO₂ antireflective films are presented. The fabricated nonlinear optical elements have certain advantages for generating IR and terahertz radiation via nonlinear frequency conversion.

The differences in microstructure and mechanical behavior between the wrought and electron-beam additively manufactured (EBAM) specimens of the AISI 321 stainless steel and CuSi3Mn1 copper-based alloys are studied, with a focus on the crack growth characteristics. The microstructure is examined using transmission electron microscopy. The mechanical properties are evaluated by the Vickers microhardness testing, static tensile tests, and fatigue crack growth experiments on compact tension specimens. The fatigue crack growth behavior is analyzed using a threshold stress intensity factor (SIF) range (∆K_th) and a regression analysis of the latter versus the fatigue crack growth rate (da/dN). The EBAM AISI 321 steel exhibits lower tensile and yield strengths but higher microhardness and strain at failure, indicating an enhanced ductility and a reduced crack sensitivity. However, it shows a lower threshold stress intensity factor range compared to the wrought steel. The EBAM specimens of the CuSi3Mn1 alloy demonstrate significantly lower strength, yield stress, and microhardness, accompanied by an increased elongation at break. The increased ductility of the AM CuSi3Mn1 alloy corresponds to a higher threshold stress intensity factor range.

Using transmission electron microscopy, the paper investigates the structure and strength properties of polycrystalline alloys based on the Cu-Al system with mesoscopic grains. The analysis of the mechanical behavior is based on quantitative parameters of the grain and dislocation structures and long-range stresses. Strain hardening mechanisms are discussed herein, involving the experimental data on the evolution of deformed grain and defect structures.

The properties of Polysulfone electrets, thermally stimulated by depolarization current (TSDC), are investigated in the temperature range of 30 to 210 °C as a function of the polarizing field (5 to 100 kV/cm) and polarizing temperature (40 to 80 °C). The two peaks in the TSDC spectra are termed β and α, and they are located at around 68 °C and 172.5±173.5 °C, respectively. Here, β denotes relaxation processes, while α represents primary (segmental) relaxation or glass transition. These are explained by the space charge motion and dipole orientation, respectively. It is observed that the space charge peak (α) is more responsive to the forming rather than dipole-related parameters. A continuous relaxation distribution is suggested by the observed activation energy relationship for different peaks and the peak temperature parameter dependence on the polarizing temperature. To study the structural characterization, the FT-IR, UV-Vis and XRD analyses are carried out. The microstructural properties of Polysulfone are explained through the Scanning Electron Microscopy (SEM). The spectroscopic analysis confirms that Polysulfone has repeating units of ether and sulfone groups; it is an aromatic amorphous thermoplastic polymer.

In this work, Tri caesium di-molybdate (VI) bromide—TCDMB crystals is well-grown using the solution growth method. Nano-TCDMB crystals are obtained properly by 34-hour milling of macro-TCDMB crystals, and the 25 nm sample is investigated by the powder XRD, SEM and TEM. The interactive profile of TCDMB for normalized and shaped profile represent projections of the TCDMB material normalized and non-linear optical behaviour; the electrical condition, dielectric constant and dielectric loss of nano-TCDMB initially at higher values at lower frequency limits and gradually getting reduced over increase in the frequency limits and variance in logf value, are especially by the milled impact. Also, the higher dielectric constant at room temperature affects the nano-TCDMB crystal that can predict its use in super-capacitors. The nano-TCDMB crystal provides the emission at 541 nm with the band gap of 2.2920 eV in greenish way of fluorescence. The anti-diabetic utility of alpha-amylase and alpha-glucosidase based in-vitro activity of nano-TCDMB is reported. The sensor activity of TCDMB is reported for macro, nano and is 7% and 8%, respectively. So, nano is preferred than macro/micro by sensory and bio-activities.

The performance of metal matrix composites (MMCs) is strongly influenced by the distribution and volume fraction of reinforcement particles within the matrix. Among MMCs, aluminum-based composites, especially those reinforced with zirconium carbide (ZrC), have attracted significant attention due to their superior strength, wear resistance, and thermal stability. Accurate quantification of the reinforcement and matrix phases is essential to understand and tailor the composite’s mechanical behavior. In this study, a fully automated image processing methodology is proposed for the segmentation and calculation of the volume fractions of ZrC and aluminum (AA7075) phases from the scanning electron microscopy-backscattered electron (SEM-BSE) images. This approach utilizes a systematic imaging pipeline involving grayscale conversion, Gaussian blurring for noise reduction, and Otsu’s thresholding for optimal phase separation. The colored masks are generated to visually differentiate between the matrix (green) and reinforcement (red) phases, followed by the formation of combined overlay images for an effective phase visualization. The automated algorithm accurately computes the area-based volume fractions, showing a significant variation across the samples with different ZrC contents. It is shown that the use of BSE imaging enhances the phase contrast, enabling precise detection and quantification. This method demonstrates a rapid, reproducible, and operator-independent approach for microstructural characterization, offering valuable insights for optimizing the fabrication of composites and their property control.

It is demonstrated that the process of discharge development in the pseudospark switch at a current of about 1 kA is significantly different for the case of the external switch triggering and for the static breakdown conditions. With external discharge initiation, the current rise is caused by the development of the dense glow discharge with hollow cathode and the superdense glow discharge with the explosive emission processes on the cathode surface. For the static breakdown, the arc cathode spot is formed at an early temporal stage, and the total switching current flows to this spot. Physical reasons for such a peculiarity are discussed.

The paper investigates the surface treatment by low-temperature plasma affecting the laser-induced damage threshold of ZnGeP₂ single crystals. It is found that the surface exposure to plasma with the electron density of 10¹⁴ to 10¹⁵ cm^–3, 13–20 kV voltage, and 50–100 Hz pulse frequency for 500,000 pulses with a duration of ~40 ns, leads to an increase in the damage threshold by 30%. This effect is attributed to the thickness reduction of the damaged near-surface layer.