Химия

Phase equilibria and critical phenomena in the ternary system potassium nitrate – water – methyldiethylamine, where a constituent binary liquid system is characterized by phase separation with a lower critical solution temperature (LCST), were studied by means of the visual-polythermal method within 25–55°C.

A novel scheme of the isothermal phase diagram of the quaternary system salt + three solvents with three liquid-phase equilibrium (its ternary liquid subsystem to be characterized by a band-like delamination region) was deduced by means of the topological transformation method.

Complexation of the rare-earth elements (REE) La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb with o-phthalic acid was studied potentiometrically at 298 K and an ionic strength of 0.2 (KCl). Complex species MHA²⁻ and MA⁺, M being REE and A – C₆H₄O₄²⁻, were detected. The pH range and stability constants of the complexes were established.

The structure of complexes of lithium, sodium, and potassium cations with molecules of several aprotic solvents (diethyl carbonate, dimethyl sulfoxide, and dimethyl formamide) was studied by means of the density functional method. Changes in the geometry and electronic structure of the solvent molecules at their coordination with an alkaline metal ion are considered.

Optimal conditions for synthesis of 2,4-diphenyl-5-oxo-5,6,7,8-tetrahydrochromillium salts on the basis of triketones of 2-(1,3- diphenyl-3-oxopropyl)-cyclohexanedione-1,3 have been found. For the first time the ability of oxo-1,5-diketones with no substituent at C-1 of the side chain to form salts has been established.

In the traditional method of removing excess acid used to obtain the salt form of chitosan, not only a reaction with neutralizing bases proceeds, but also partial deprotonation of macrochains. Since charged amino groups are responsible for the biological activity of the aminopolysaccharide, it seems important to develop methods for optimizing the acid–base composition of a chitosan-containing system without proton elimination.

The substances that make up the three-component reciprocal system of fl uorides and chlorides of potassium and cadmium have various applications, both individually and in mixtures. The faceting elements of the ternary reciprocal system include in binary systems the formation of compounds KF∙CdF2 , KCl∙CdCl2 of congruent and compound 4KCl∙CdCl2 of incongruent melting. The crystallization tree is constructed. Taking into account the compounds, a crystallization tree has been constructed that has a linear structure and includes fi ve stable secondary triangles.

Expanding the beer assortment by partially replacing barley malt with new types of raw materials based on grain crops is a promising direction for the industry development. A promising grain crop that can partially replace barley malt is triticale. The aim of the work is to study the possibility of using triticale grain and malt for partial replacement of barley malt in beer production and to evaluate the eff ect of this raw material on the physicochemical and organoleptic quality indicators using the principal component analysis (PCA).

An important aspect of modern analytical chemistry is the study of multicomponent objects, including medicinal plants with clinically proven pharmacological activity, and promising plants from the point of view of pharmacy, which are not offi cinal, but belong to the same family. In addition, it is of interest for pharmacy to determine the content of valuable types of fl avonoids (rutin, cynaroside, luteolin) in these plants, due to their high antitumor activity.

One of the promising directions of carbon-neutral energy development is the development of technologies for biofuel production from microalgae. Eff ective control of biotechnological processes in the fi eld of cultivation of such microalgae requires express and eff ective methods of process control. In this study, a fl ow-through photometric cell has been designed and fabricated for online determination of the biomass content of the microalgae Nannochloropsis sp. in the culture medium. The microalgae biomass has been cultured in a custom-made photobioreactor.