Astrakhan State University

The review systemizes literature data on the synthesis, chemical transformations, and application of Bett bases over a period of 2004 to 2025. Various aspects of the classical Betti reaction, including conditions, catalysts, solvents, selectivity, mechanism, and compliance with the “green” chemistry principles, are con­sidered in detail. The effects of different catalysts on the yield, reaction time, and selectivity are compared. Particular attention is given to the transformations of Betti bases, especially oxidative cyclization reactions, rearrangements, reactions with nucleophilic and electrophilic reagents, as well as reactions involving o-quinone methides generated therefrom. The stereochemical output of the reactions with chiral substrates is analyzed with respect to chiral auxiliary, substituent nature, catalyst, and solvent. Examples of application of Betti bases in both fundamental research (as ligands in asymmetric catalysis) and applied fields, such as medicinal chemistry and pharmacology, are given.

Eustrongylides spp. are helminths with a multiple-host life cycle that can infect aquatic oligochaetes, various freshwater fish, fish-eating birds, and accidental mammalian hosts, including humans. This work aimed to morphologically and molecularly characterize the larval stages of Eustrongylides spp. isolated from European perch, and to outline the oxidative/nitrosative stress and histoarchitecture changes induced by active larval migration or tissue-encapsulation. Eighty Perca fluviatilis were collected from the Volga River (Astrakhan, Russia). Thirty-seven were tentatively grouped as infected based on the grossly visible Eustrongylides larvae in the oral cavity, gills, axial muscles, and internal viscera. The nematodes were examined microscopically and characterized at the molecular level by PCR amplification of nuclear small-subunit ribosomal RNA (nSSU-rRNA) gene fragments, followed by sequencing and phylogenetic analysis. Affected organs were evaluated for redox/ nitrosative status and histopathological tissue injury. Fifteen healthy fish were selected as controls. Morphological examination identified the isolated nematodes as Eustrongylides sp., which were subsequently identified as Eustrongylides excisus (E. excisus) by molecular analysis, contributing to an infection rate of 46.25% (37/80). E. excisus was identified based on 100% sequence identity with available GenBank references, although the 18S rRNA marker provides limited species-level identification. Our findings demonstrate that E. excisus infection triggers a significant shift in the host's oxidative and nitrosative burden. This oxidative-inflammatory response leads to marked pathological changes in affected organs, including blood vessel dilation, mononuclear cell infiltration, vacuolar degeneration, and necrosis. Ultimately, these larvae induce severe cellular damage in fish muscle and visceral organs, disrupting cellular integrity essential to normal physiological function.

The decline in physical activity among modern schoolchildren highlights the problem of developing sustainable habits of systematic physical education participation. The purpose of the study is the theoretical substantiation and experimental verification of the effectiveness of an integrated pedagogical model for developing physical activity skills in schoolchildren within a modern educational organization. Research methods and organization. Theoretical analysis of scientific and methodological sources, pedagogical observation, questionnaires, pedagogical experiments, and methods of mathematical and statistical data processing were applied. The research was carried out throughout the academic year based on general education schools in the city of Astrakhan, involving students of grades 5–7. Research results and conclusions. An integrated model has been developed and tested, combining curricular, extracurricular forms of organizing activities and interaction with the family. An increase in the volume of physical activity has been established in both boys and girls; an increase in motivation for systematic physical education classes has been identified. The effectiveness of developing physical activity skills is ensured through the application of an integrated approach, personalization of content, and the creation of a motivating physical education and health-promoting environment.

Garlic is a widely cultivated vegetable valued for its health-promoting compounds. This study investigated the effects of humic acid (HA) and potassium (K) on garlic productivity, bioactive compounds, and nutrient uptake. A field trial was conducted to evaluate treatments combining potassium sulfate (120 and 150 kg K2O ha-1) and humic acid (10 and 20 kg ha-1). Potassium and humic acid significantly enhanced garlic performance, with combined treatments producing the most potent effects. Applying humic and K significantly increased productivity. Photosynthetic pigments increased up to 22% for chlorophylls and 45.7% for carotenoids, improving photosynthesis and photoprotection. HA raised TSS by 20% and vitamin C by 32%. Potassium enhanced TSS by 24%, carbohydrates by 3%, and vitamin C by 28%. Combined treatments maximized TSS (+32%) and vitamin C (+38%), with polyphenols restored to 40%. Bioactive compounds, metabolites, and antioxidants were enhanced, with proline up to 45%, H2O2 up to 55.7%, APX up to 25%, SOD up to 42%, and CAT up to 25-79%, indicating improved osmotic and oxidative management. Nutrient uptake (N, P, Ca, Mg, S, and K) improved markedly, highlighting balanced nutrient allocation from leaves to cloves. Moderate combinations (K120+HA10) maximized yield, improved photosynthetic pigments, increased vitamin C and total soluble solids, and balanced nutrient allocation between cloves and leaves. These results demonstrate that integrating HA and K provides a practical strategy to support sustainable production under nutrient-efficient management.