No abstract

Upon modification of V 2 O 5 with SnO 2 or ZrO 2 , increase in the activity and selectivity of the vanadium-oxide catalyst in the vapor-phase oxidation of 3-methylpyridine into nicotinic acid were observed. It was shown that the promoting effects of SnO 2 and ZrO 2 were the result of increases under their influence of the proton affinity of the vanadyl oxygen and decreases in the enthalpy of deprotonation of the methyl group of the substrate, connected by a nitrogen atom with the Lewis acidic center (vanadium ion). The given characteristics were calculated by the density functional theory quantum-chemical method. Modification of binary V 2 O 5-SnO 2 and V 2 O 5-ZrO 2-catalysts by TiO 2 addition resulted in a further increase in the nucleophility of the vanadyl oxygen and, as a consequence, an increase in the catalytic activity and selectivity for nicotinic acid formation.

The genome editing approach using the components of the CRISPR/Cas system has found wide application in molecular biology, fundamental medicine and genetic engineering. A promising method is to increase the efficacy and specificity of CRISPR/Cas-based genome editing systems by modifying their components. Here, we designed and chemically synthesized guide RNAs (crRNA, tracrRNA and sgRNA) containing modified nucleotides (2’-O-methyl, 2’-fluoro, LNA—locked nucleic acid) or deoxyribonucleotides in certain positions. We compared their resistance to nuclease digestion and examined the DNA cleavage efficacy of the CRISPR/Cas9 system guided by these modified guide RNAs. The replacement of ribonucleotides with 2’-fluoro modified or LNA nucleotides increased the lifetime of the crRNAs, while other types of modification did not change their nuclease resistance. Modification of crRNA or tracrRNA preserved the efficacy of the CRISPR/Cas9 system. Otherwise, the CRISPR/Cas9 systems with modified sgRNA showed a remarkable loss of DNA cleavage efficacy. The kinetic constant of DNA cleavage was higher for the system with 2’-fluoro modified crRNA. The 2’-modification of crRNA also decreased the off-target effect upon in vitro dsDNA cleavage.

This research examines the use of coal-processing wastes of Shubarkol deposit (Kazakhstan) in obtaining useful materials such as carbon fibers. For our experiments, mesophase pitch was obtained by coal tar heat treatment at 773 K. Spinnable solution was prepared by crushing mesophase pitch into the pieces with adding poly(methylmethacrylate) as a fiber-forming material and 1,2-dichloroethane as a solvent. Elemental analysis revealed that the chemical composition of mesophase pitch (С – 91.48 %; О – 8.52 %; S – 0.00 %) showed that heat treatment up to 773 K leads to the complete removal of sulfur-containing components which affect the mesophase formation. Raman data of the obtained pitch revealed the appearance of D (1366 cm-1) and G (1605 cm-1) peaks, which are responsible for carbon materials; another peak at 2900 cm-1 shows the presence of C–H bonds. Carbon fibers with the diameter of 0.8–1.75 μm were obtained by electrospinning method in laboratory settings.