Recently, the use of plant-origin materials has become especially important due to the aggravation of environmental problems and the shortage and high cost of synthetic materials. One of the potential candidates among natural organic compounds is polysaccharides, characterized by a number of advantages over synthetic polymers. In recent years, natural polysaccharides have been used to design composite catalysts for various organic syntheses. This review is devoted to the current state of application of polysaccharides (chitosan, starch, pectin, cellulose, and hydroxyethylcellulose) and composites based on their catalysis. The article is divided into four main sections based on the type of polysaccharide: (1) chitosan-based nanocomposites; (2) pectin-based nanocomposites; (3) cellulose (hydroxyethylcellulose)-based nanocomposites; and (4) starch-based nanocomposites. Each section describes and summarizes recent studies on the preparation and application of polysaccharide-containing composites in various chemical transformations. It is shown that by modifying polysaccharides, polymers with special properties can be obtained, thus expanding the range of biocomposites for catalytic applications.

Solid waste management is one of the main problems in large cities. The determination of the quantitative and qualitative composition of municipal solid waste is necessary for proper planning in the processing of such waste. This article presents the results of studies of the morphological composition, physico-chemical parameters and energetical potential of municipal solid waste (MSW) from the landfill of the city of Shymkent. Waste samples were taken from 10 different points of the landfill. The volume–mass parameters of the samples and their average density were determined. The combined waste samples mainly consisted of food waste, paper and cardboard, polymers and plastic, glass, metal, textiles, wood, leather, bones and rubber. Most of the waste, more than 30%, contains plastic products. The moisture of the combustible fraction of the samples is low and varies from 0.3% to 2.3%. The average ash content of the combustible fraction of the samples was determined and its average value is 18.4%. The yield of the volatile substances was determined and the average value per dry state is 78.7%. To determine the energetical potential of municipal solid waste, the gross calorific value was determined and the net calorific value was calculated, the average value of which is 24.15 MJ/kg. This shows the possibility of using solid waste as an energy source.

In Central Eurasia, the availability of drugs that are inhibitors of the SARS-CoV-2 virus and have proven clinical efficacy is still limited. The aim of this study was to evaluate the activity of drugs that were available in Kazakhstan during the acute phase of the epidemic against SARS-CoV-2. Antiviral activity is reported for Favipiravir, Tilorone, and Cridanimod, which are registered drugs used for the treatment of respiratory viral infections in Kazakhstan. A licorice (Glycyrrhiza glabra) extract was also incorporated into this study because it offered an opportunity to develop plant-derived antivirals. The Favipiravir drug, which had been advertised in local markets as an anti-COVID cure, showed no activity against SARS-CoV-2 in cell cultures. On the contrary, Cridanimod showed impressive high activity (median inhibitory concentration 66 μg/mL) against SARS-CoV-2, justifying further studies of Cridanimod in clinical trials. Tilorone, despite being in the same pharmacological group as Cridanimod, stimulated SARS-CoV-2 replication in cultures. The licorice extract inhibited SARS-CoV-2 replication in cultures, with a high median effective concentration of 16.86 mg/mL. Conclusions: The synthetic, low-molecular-weight compound Cridanimod suppresses SARS-CoV-2 replication at notably low concentrations, and this drug is not toxic to cells at therapeutic concentrations. In contrast to its role as an inducer of interferons, Cridanimod is active in cells that have a genetic defect in interferon production, suggesting a different mechanism of action. Cridanimod is an attractive drug for inclusion in clinical trials against SARS-CoV-2 and, presumably, other coronaviruses. The extract from licorice shows low activity against SARS-CoV-2. At the same time, high doses of 2 g/kg of this plant extract show little or no acute toxicity in animal studies; for this reason, licorice products can still be considered for further development as a safe, orally administered adjunctive therapy.

Kazakhstan’s asbestos industry produces over 3 million tons of waste annually. The primary component of asbestos ore waste (AOW) is magnesium rich minerals. In this study, the extraction of magnesium from AOW with nitric acid (HNO₃) was for the first time systematically studied. A series of experiments were conducted to optimize acid concentration (300–600 g/L), leaching temperature (55–95 °C), leaching time (60–180 min), solid-to-liquid ratio (1:3–1:7), and particle size, with the overall goal of maximizing magnesium extraction and cost efficiency. Our results provide dependence of magnesium extraction in the order of acid concentration > temperature > time > solid-to-liquid ratio, while particle size was found to be negligible. The cost-efficiency optimization demonstrated the positive impact of the relatively low acid concentrations (< 450 g/L) and temperatures between 65 and 85 °C, while the Protodyakonov model validated a linear dependence of the extraction rate on temperature and acid concentration. Our model demonstrates that extraction efficiencies of up to 90% can be achieved while reducing reagent use and lowering the overall cost of magnesium production. Leaching of magnesium by HNO₃ also opens a pathway to a closed-cycle process, due to the formation of magnesium nitrate. The thermal decomposition of Mg(NO₃)₂ provides valuable products such as MgO and NO₂ reused in HNO₃ regeneration for subsequent cycles. The proposed model predicts magnesium extraction from asbestos ore depending on leaching parameters with reasonable accuracy.