SYNTHESIS OF COCRYSTALS OF BETULIN WITH SUBERIC ACID AND STUDY OF THEIR PROPERTIES

Lupane triterpenoids, betulin and its derivatives, are attracting great interest due to their wide range of biological and pharmacological activities. However, the poor solubility of betulin and its derivatives in aqueous media significantly reduces their bioavailability. Obtaining cocrystals, that is, multicomponent crystal systems containing active pharmaceutical ingredients and non-toxic partner molecules in their structure, is used in pharmacy to change the physicochemical properties of drugs, including the rate of dissolution and solubility. In this study, cocrystals of betulin with suberic acid were obtained by liquid-assisted grinding method using organic solvents of different polarity: ethanol, acetone, ethyl acetate, chloroform, toluene, dioxane. The formation of cocrystals was confirmed by X-ray diffraction analysis, IR spectroscopy, and thermal analysis. It has been shown that cocrystals of betulin with suberic acid contain water molecules in their structure; anhydrous cocrystals can be obtained by heating a physical mixture of reagents until the acid melts. The results of experiments on the dissolution of cocrystals of betulin with suberic acid in comparison with the data for cocrystals of betulin with adipic acid showed that an increase in the length of the aliphatic acid chain leads to a decrease in the rate of betulin release into solution.

MECHANISMS OF MAGMATIC MINGLING IN COMPOSITE DYKES: MODELS OF DISPERSION AND SHEAR DILATATION

This article is focused on the intrusion and formation of combined dykes. Two main groups of conventionally magmatic mingling are distinguished: (1) plutonic bodies, and (2) combined dykes. The first group is represented by small basite inclusions that are uniformly scattered in granitoid bodies, and includes elongated swarms and tails of small bodies. The second group includes composite dykes with the indicators of mechanical mingling of basic and acid melts. Despite the similarities in the structural and textural features and the indicators of mechanical mingling of melts, these two groups are characterized by clearly different proportions of the volumes of contrasting melts and differ in the duration of formation, place of melt mingling, and tectonic setting. None of the available models was able to explain the occurrence of magmatic mingling structures in individual dykes. In our study, the mingling mechanisms of contrasting melts are discussed using the data on the geological objects located in West Sangilen, an area of the Central Asian Orogenic Belt (CAOB). The general and specific parameters of combined dikes of the Saizyral and Tavyt‐ Dag sites are considered. The models of shear dilatation and dispersion are proposed for explaining the mechanisms of magmatic mingling in combined dykes.

The characteristic of acid melts which formed tephra of pleistocene-holocene eruptions of Ichinsky Volcano, Kamchatka (Results of melt inclusions study)

This paper presents the results of a study of melt inclusions in plagioclase, amphibole and pyroxene from Ichinsky volcano’s tephras of different age. Two types of melts have been identified, distinguished by different concentrations of potassium (K2O). Major and trace elements’ composition of these melts indicates that magma mixing was the dominating process in the Ichinsky magmatic system.

Flow and Die-Swell Behavior in Extrusion of PLLA Melts

The rheological properties of two kinds of poly (L-lactic acid) melts (AI-1001 and 4032D) have been investigated using a melt flow indexer within the temperature range from 170 to 190 and load varying from 2.16 to 12.5 kg. It was found that the melt volume flow rate (MVR) and extrudate swell ratios (B) increased non-linearly with increasing load when the temperature was constant; the MVR increased while the B decreased with a rise in temperature for both the AI-1001 and 4032D melts; the relationship between the MVR and temperature obeyed expression like as the Arrhenius equation when the load was fixed. Under the same test conditions, the values of the MVR and B of the AI-1001 melt were higher than those of the 4032D melt, and the sensitivity of the MVR and B to the load for the former is higher than those for the latter.