Physics of Atomic Nuclei最新文献

Results are presented from designing an 8-MeV linear electron accelerator associated with modeling a two-section accelerating structure and microwave power coupler devices. The dynamics of the electron beam in the accelerator is simulated using the BEAMDULAC-BL program. Results are used to adjust a electrodynamic model of the accelerating structure with couplers and obtain values of its electrodynamic characteristics.

Chromium coatings can significantly improve the corrosion resistance of fuel rod cladding made from EP823-Sh steel in liquid lead environments at temperatures up to 650°C. To ensure the long-term effectiveness of the coating, it is crucial to prevent the diffusion interaction between the chromium layer and the underlying steel throughout the operational lifespan of the fuel rod. High-temperature tests on samples reveal a coating-steel interaction layer. At 420°C, with a holding time of 1000 h, the coating retains its adhesion to the steel, and no interaction is observed between the two materials. However, at 540°C and 650°C with a holding time of 1000 h, a diffusion layer with uneven thickness (ranging from 150 to 600 nm) forms at the coating-steel interface. This layer, which has a complex composition, effectively blocks further diffusion of elements from both the coating and the steel. The EP823-Sh steel contains approximately 1 wt % molybdenum and tungsten, which promote the coating-steel interaction. Overall, the results suggest that chromium coatings are a promising option for enhancing the corrosion resistance and longevity of fuel rod cladding made from EP823-Sh steel.

In this work, nanoparticles of aluminum, copper, and titanium oxides were obtained by plasma discharge in the liquid phase (ethylene glycol, water) under the influence of intense ultrasound. Particular procedures have been developed for creating sedimentation-stable aqueous dispersed systems of nanoparticles of copper(II), aluminum, and titanium(IV) oxides. Nanoparticles are stabilized by the nonionic surfactant Tween 85 at its optimal concentration of 3 mmol/L and with a metal oxide content of up to 0.2 g/L. It has been shown that stable dispersed systems of particles are obtained by adding a surfactant to the initial system, followed by diluting it with distilled water and ultrasonic dispersion. Using scanning electron microscopy, it was shown that nanoparticles of copper, aluminum, and titanium oxides have a spherical shape. Highly stable dispersed systems with a narrow particle size distribution were obtained: 20 nm for Al₂O₃, 40 nm for CuO, and 30 nm for TiO₂ after membrane filtration of the initial dispersed systems. Electrokinetic studies have shown that the surface of nanoparticles of copper, aluminum, and titanium oxides becomes negatively charged when stabilized by Tween-85. The average value of the ξ-potential was –20 ± 5 mV. The study of the kinetics of growth and stability of nanoparticles showed that titanium oxide nanoparticles, under equal conditions, have higher aggregation stability compared to copper and aluminum oxides. The stability time of the obtained samples was approximately 1.5 months.

Resonant cavities based on porous silicon (pSi) are of interest as a basis for hybrid photoluminescent (PL) systems from the viewpoints of both fundamental and applied research. One of the most promising fluorophores for creating such hybrid systems is semiconductor quantum dots (QD), due to their narrow PL spectra and broad absorption spectra. Depending on the structure and parameters of a hybrid system, polariton states can be created and the PL properties of the embedded fluorophores can be modified. This work describes a 4.4-fold narrowing of the PL spectrum of CdSe/ZnS semiconductor quantum dots (core/shell) and a 3.7-fold acceleration of spontaneous emission in pSi microcavities, relative to similar parameters of QDs in a solution. The observed changes in the PL properties of QDs are attributed to the interaction of light and matter between the microcavity eigenmode and the QD excitons. The obtained results pave the way for developing new photonic and optoelectronic devices.

Oncological diseases, constituting a major global cause of death, require more selective treatments to minimize side effects. Immunotherapy using antibodies targeting immune checkpoints is a promising approach, but it is limited by poor tumor penetration and treatment resistance of cancer cells. The use of biocompatible and biodegradable calcium carbonate microparticles as drug carriers offers a solution due to their capacity for encapsulation of biomolecules and control of their release, which increase the therapeutic efficacy while reducing side effects. Our study was aimed at optimizing the synthesis of calcium carbonate microparticles and improving the loading of bovine serum albumin, used as a model protein, into them by means of coprecipitation. The approaches developed here make it possible to obtain protein carriers with advanced morphological characteristics and with a loading efficiency of more than 90%.

The strategy for detecting collapsing stars in the Galaxy using a pair of instruments including the OGRAN optoacoustic gravitational detector and the BUST neutrino scintillation telescope, located in the ground laboratories of the Baksan Neutrino Observatory, Institute for Nuclear Research, Russian Academy of Sciences, is discussed. A key element of the strategy is the search for correlated responses from both detectors, the so-called search for neutrino-gravitational correlations. The efficiency of various algorithms for joint data processing, including analysis of the CH1987A event, is assessed. The processing technique is illustrated using the current output signals of the mentioned instruments.

Accelerator complexes with a chain of accelerators have been created in recent years for solving relevant problems of particle physics and application research. These chains consist of accelerators for intermediate energies, the main accelerator for project beam parameters, experimental stations, and beam transfer channels. Operation with a synchrotron accelerator requires the correction of a closed beam orbit. Automatic software is developed for this purpose. The main features of software development for beam orbit correction in ring accelerators and colliders are described for the NICA complex booster synchrotron as an example. Multipurpose methods have been used for general application in beam orbit correction systems.

Monte Carlo (MC) calculations are made for a two-dimensional model of a layered HTS. The strength of the electric field is calculated for samples subjected to rectangular pulses of current with amplitudes exceeding the critical value. The model considers the heating of the sample caused by the flow of current. Calculations are made for different strengths of magnetic fields and amplitudes of pulse currents. The effect an external magnetic field has on the shape of the response of a superconductor to a rectangular current pulse is determined.

The method of pulsed laser deposition (PLD) has attracted increasing attention as a promising approach for optimizing catalysts to enhance their efficiency in various applications. One of the current challenges is the simple and controllable synthesis of materials based on transition metal chalcogenides (in particular, MoS_x), which can exhibit an increased electrocatalytic activity in the hydrogen evolution reaction. Changes in the chemical states of sulfur and molybdenum as a result of photoelectrochemical tests are studied in this work. By varying the laser fluence and buffer gas pressure, deposition regimes have been determined that result in catalytic layers with minimal substoichiometric states, which are responsible for shifting the Fermi level to the conduction band edge. Combining experimental results and DFT calculations, catalytically active sites on the film surfaces have been identified.

The authors consider current ways of studying the 3D nanostructure of  biomaterials and biological objects based on scanning probe nanotomography—a combination of fluorescence microscopy, probe microscopy, and ultramicrotomy. Results are presented from experiments to study the 3D nanostructure of composite scaffolds based on Bombyx mori silk fibroin and microparticles of an extracellular matrix obtained from decellularized liver tissue. Such scaffolds have great potential for using in regenerative medicine. It is shown that probe nanotomography allows effective analysis of the 3D nanostructure of microinclusions and their morphological parameters that influence the biological activity of products.