Russian Journal of General Chemistry最新文献

A high turbidity of water is observed in a fish pond with a high content of organic matter. Because of this, phytoplankton develops poorly. Daphnia longispina predominated among zooplankton, consuming small-sized detritus, bacteria, and other suspended organic matter. Daphnia was located in the upper part of the reservoir. The fish in the studied pond were large and lived mainly near the bottom. Accordingly, their trophic impact on zooplankton was low. Clarification of water in the upper layers of the pond occurs due to the high filtration activity of Daphnia.

Carbon nanoparticles resembling gravel were successfully prepared by self-aggregation of sodium dodecylbenzene sulfonate (SDBS) based on the concentrated salt NaBr system, which could be named as nano-carbon gravel (NCG). Thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), Scanning electron microscopy (SEM), Raman spectroscopy (Raman), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS) and photoluminescence (PL) were used to perform a series of characterizations of NCG. The results showed that the prepared NCG had the intrinsic properties of carbon materials, which were mainly characterized by amorphous carbon with some graphite features. It is worth noting that the NCG widely contained a large number of particles with sizes less than 100 nm and a high degree of particle dispersion. More interestingly, it was initially found that the NCG had blue and cyan-green luminescent behaviors under different wavelength excitations in the range of 360–420 nm, suggesting that it might have some potential applications in the optical field. This method was operable, environmentally friendly and low-cost, and NaBr only played an important role in separation and protection in the construction stage of carbon nanomaterial morphology in the experimental process, and could be effectively recycled after being dissolved by water washing.

Herein, we report a metal-free, photoelectrochemical (PEC) strategy for the direct C–H amination of guaiacol. Using a rationally designed PEC system, we achieved efficient amination with a range of nitrogen nucleophiles, including phenothiazines (PTZs) and phenoxazine (PNX), affording the corresponding products in yields of up to 90%. This operationally simple protocol demonstrates the unique potential of PEC to enable challenging transformations under mild conditions, providing a sustainable route to valuable N-arylamines.

This paper describes the synthesis and investigation of new substituted potassium 3-(thiophen-2-yl)amino-5-oxopenta-1,3-dien-2-olate derivatives which can be used in agriculture and have minimal acute toxicity. The obtained substances were characterized by FTIR spectroscopy, NMR spectroscopy, and elemental analysis. Quantitative evaluation of the cytotoxic effect of the developed compounds was identified, and it was determined the seeds germination rate, morpho- and mass-metric characteristics. The results showed that several synthesized compounds demonstrate a high level of biological activity with a low level of acute toxicity. Thus, this indicates the perspectives of further research on this class of compounds.

Diketopiperazines, or cyclic dipeptides, represent an important class of biologically active compounds with a broad spectrum of functional properties. Solid-state synthesis of cyclic dipeptides from their linear analogs upon heating is a promising strategy. In this study, the solid-state cyclization of the dipeptide _L-phenylalanyl-glycine is investigated for the first time. The structure of the product is determined using a combination of physicochemical methods. A kinetic analysis of this reaction is performed, and the kinetic parameters are determined. Atomic force microscopy demonstrates the effect of solvent on the self-assembly of cyclo(Phe-Gly). These results expand our understanding of the mechanisms of dipeptide cyclization in the solid state and the potential for their use as building blocks for functional and bioinspired materials.

As a result of the reaction between 5-hydroxy-4-oxo-4H-pyran-2,6-dicarboxylic acid (meconic acid, poppy acid) and magnesium acetate, a complex with the composition C₂₈H₆₂Mg₃O₅₄ {[Mg(H₂O)₆]₃·(Mec^2–)₂(HMec^–)₂· 8H₂O} was synthesized. The composition of the complex was determined based on energy-dispersive X-ray spectroscopy and atomic absorption spectroscopy. The structure of the complex was studied using spectroscopic methods (NMR, IR spectroscopy) as well as X-ray diffraction analysis. Based on potentiometric titration data and quantum chemical calculations, a possible composition of the magnesium complex with meconic acid in an aqueous solution was proposed. In vivo experiments demonstrated that the oral administration of magnesium meconate over 30 days promotes the accumulation of Mg²⁺ in myocardial tissues and activates the antioxidant potential by enhancing the expression of a number of antioxidant defense system proteins, such as Gclc, NFE2L2, SOD2, and CAT.

Using methods of electrical conductivity, photosedimentometry, viscometry, and optical microscopy, the regions of relative stability of highly concentrated oil-in-water emulsions of an epoxy oligomer were determined. These emulsions were prepared with nonionic surfactants as emulsifiers and high-molecular-weight compounds or solid microparticles (synthetic latexes and mineral powders) as stabilizers. The introduction of stabilizers significantly affected the size and mass distributions of dispersed-phase droplets, depending on the chemical nature, size, and concentration of the solid microparticles. This led to a marked improvement in the aggregative and sedimentation stability of the emulsions and enhanced their film-forming ability. The films and coatings obtained by curing these emulsions were comparable in physicochemical and operational properties to those produced from epoxy resin solutions in organic solvents.

As a result of a monitoring study of changes in the concentrations of trace elements and biogenic ingredients in the waters of the foothill and estuarine zones for the period 2002‒2023, data were obtained on the composition and quality of the Baksan River waters in a changing climate. The seasonal dynamics of the concentrations of the components under study are presented. As a result of data comparison, it was revealed that in recent years (2020‒2023) the composition of river water has changed upward for some elements, being pollutants of the river waters, while for others there is relative homogeneity and is within the permissible concentrations. The variability of pollutant concentrations by seasons is shown. The interannual variability of the concentrations of trace elements and biogenic components in the Baksan waters in the main phases of the hydrological regime over a long-term period ‒ winter low water and summer rain flood—is considered. The results are presented in tables.

The work investigates the sorption of metals from the water of the Gulf of Finland using a chitosan-based biosorbent obtained from the biomass of Rhizopus oryzae F-814. The mechanisms of interaction between metal ions and the sorbent have been analyzed. The sorption capacity and degree of sorption for 24 metals have been analyzed. The obtained results confirm the effectiveness of the fungal sorbent for water purification in natural water bodies.

This study assesses metal ion contamination (24 elements) in the waters of the Gulf of Finland using inductively coupled plasma mass spectrometry (ICP-MS). Water samples were collected from three distinct locations, including areas affected by wastewater treatment facilities and the flood protection complex. The results revealed multiple exceedances of the maximum permissible concentrations for several elements. Potential pollution sources were analyzed, with particular attention to microbiologically influenced corrosion contributing to metal release into the aquatic environment. The findings highlight the urgent need to strengthen environmental monitoring and to develop effective strategies for mitigating anthropogenic pressure on the Gulf of Finland ecosystem.