Issue 4 (Volume 2) 2025

In the framework of the extended Nambu–Jona-Lasinio model, the processes τ → ππη(η′)ν_τ and τ → πηη(η′)ν_τ are considered taking into account mesons in the ground and first radially excited intermediate states. It is shown that in the processes τ → ππη(η′)ν_τ the vector channel is dominant, and in the processes τ → πηη(η′)ν_τ the main contribution is given by the axial-vector channel. The scalar meson a₀ plays a dominant role in processes with two η mesons in the final state. The significance of the relative phase between the ground and first radially excited states for these processes is shown. The obtained results for the τ → ππην_τ process are in satisfactory agreement with the recent experimental data from BaBar and CMD-3, which differ from the averaged values given in the PDG tables.

General Relativity (GR) was created in November 1915, and since its creation this theory has undergone many tests. The first realistic cosmological models were proposed in the works of Friedmann, written in the 1920s. For a long time, Friedmann’s cosmological works were actually banned in the Soviet Union due to philosophical reasons, since the models where the birth and evolution of the Universe occurs were considered ideologically unacceptable. Due to great achievements in relativity and cosmology and due to increasing interest in these branches of science in the last decades, we recall the development of relativistic astrophysics and contribution of Russian researchers to these studies. Since one of the world leaders in physical cosmology A. A. Friedmann passed away in September 1925, it is reasonable to outline the main achievements of physical cosmology over the past 100 years. We also discuss observational and theoretical achievements in confirmations of relativistic observational predictions for black holes, including the closest supermassive black hole in our Galactic Center. We outline the evolution of black hole shadow from the purely theoretical concept to observable quantities for supermassive black holes in Sgr A* and M87*.

This study provides a comparative analysis of various components of mesenchymal stem cells (MSC) conditioned media (CM) obtained using serum-containing and serum-free culture methods, revealing significant differences in their composition and potential clinical applicability. Serum-containing CM exhibits significantly higher levels of total protein, non-vesicular RNA, exosomes, and nanoparticles compared to serum-free CM, reflecting the contribution of both the MSC secretome and residual fetal bovine serum components. Ultrafiltration-based fractionation (0.2 µm–50 kDa) allows the isolation of fraction enriched in exosomes and proteins, preserving the functionally significant components of the MSC secretome. This strategy effectively captures small vesicles and mid-sized proteins while excluding larger or smaller biomolecules, enhancing utility for targeted analyses. The presented data underscore the need for context-driven CM selection and provide information for choosing the optimal strategy for obtaining the MSC secretome balancing yield, purity, and regulatory demands in MSC research and therapy.