Thermal transformation of betulin by alkaline activation

Carbonization of betulin (betulinol) as an individual carbon precursor was studied in the temperature range of 400–800°C in the presence of KOH. Differential thermal analysis and IR spectroscopy were used to determine the influence of KOH on major structural changes and the chemical composition of betulin, which occur at 400–500°C. It was shown by scanning electron microscopy and BET analysis that KOH promoted the formation of a developed specific surface (S_BET 1350–2100 m²/g) at temperatures of 600–800°C and had the greatest influence on the textural and adsorption properties of the resulting porous carbon adsorbents. It has been found that the formation of microporous carbon materials with a pore size of 1.92 nm and a specific micropore surface area of 1275 m²/g is possible upon the activation of betulin with KOH at 800°C. Betulin may be proposed to control the porosity of the carbon carriers derived from birch wood.     

Damaging Effect of Antibiotics on the Structure of Synaptonemal Complexes of Meiotic Mouse Chromosomes

The structure of synaptonemal complexes (SCs) of chromosomes of mouse primary spermatocytes were studied using electron microscopy on days 1, 10, and 36 after the completion of per os administration of drugs belonging to three groups of antibiotics: tetracyclins, macrolides, and fluoroquinolones. The antibiotics were administered to mice during ten days. At the substages of early and middle pachytene, heteromorphic SC bivalents and fragments of chromosome-core elements were detected in spermatocytes at all times studied after the administration of the antibiotics of three groups. As cells passed through the period from early to middle pachytene, the number of cells containing heteromorphic SC bivalents and the fragments of axial cores gradually decreased, which could be an indication of selection of cells with chromosomal aberrations. A high level of associations between the X chromosome and autosome bivalents (including heteromorphic ones) also favors this suggestion. A gradual decrease in the number of chromosomal aberrations was detected, as time elapsed from the completion of antibiotics administration. The study of sperm obtained from epididymises of males did not reveal significant differences in both morphology and motility of sperm between males of the control and experimental groups.