Закономерности микроструктурных изменений в титановом сплаве ВТ6 при деформации и наводороживании

Объектом исследования являются образцы титанового сплава марки ВТ6 прокатанные до различных степеней деформации методом механической прокатки. Исследование дефектной структуры проводилось с использованием методов позитронной спектроскопии, которые могут определять тип и концентрацию дефектов, а также химическое окружение данных дефектов. Однако, для получения количественной и качественной оценки количества дефектов методами позитронной спектроскопии необходима дополнительная информация о базовых дефектах и их влиянии на характеристики позитронной аннигиляции. Целью работы является анализ структурных изменений в титановом сплаве ВТ6 в зависимости от степени холоднокатаной пластической деформации и после наводороживания.The object of the study are samples of titanium alloy grade VT6 rolled to various degrees of deformation by mechanical rolling. The study of the defect structure was carried out using positron spectroscopy methods, which can determine the type and concentration of defects, as well as the chemical environment of these defects. However, to obtain a quantitative and qualitative assessment of the number of defects by the methods of positron spectroscopy, additional information is needed about the basic defects and their effect on the positron annihilation characteristics. The aim of the work is to analyze the structural changes in titanium alloy VT6, depending on the degree of cold-rolled plastic deformation and after hydrogenation

Development of a multiplex RT-PCR assay for the identification of recombination types at different genomic regions of vaccine-derived polioviruses

Polioviruses (PVs) are the causal agents of acute paralytic poliomyelitis. Since the 1960s, poliomyelitis has been effectively controlled by the use of two vaccines containing all three serotypes of PVs, the inactivated poliovirus vaccine and the live attenuated oral poliovirus vaccine (OPV). Despite the success of OPV in polio eradication programme, a significant disadvantage was revealed: the emergence of vaccine-associated paralytic poliomyelitis (VAPP). VAPP is the result of accumulated mutations and putative recombination events located at the genome of attenuated vaccine Sabin strains. In the present study, ten Sabin isolates derived from OPV vaccinees and environmental samples were studied in order to identify recombination types located from VP1 to 3D genomic regions of virus genome. The experimental procedure that was followed was virus RNA extraction, reverse transcription to convert the virus genome into cDNA, PCR and multiplex-PCR using specific designed primers able to localize and identify each recombination following agarose gel electrophoresis. This multiplex RT-PCR assay allows for the immediate detection and identification of multiple recombination types located at the viral genome of OPV derivatives. After the eradication of wild PVs, the remaining sources of poliovirus infection worldwide would be the OPV derivatives. As a consequence, the immediate detection and molecular characterization of recombinant derivatives are important to avoid epidemics due to the circulation of neurovirulent viral strains. © 2016, Springer Science+Business Media New York

Highly stable hexitol based XNA aptamers targeting the vascular endothelial growth factor

Biomedical applications of nucleic acid aptamers are limited by their rapid degradation in biological fluids and generally demand tedious post-selection modifications that might compromise binding. One possible solution to warrant biostability is to directly evolve chemically modified aptamers from xenobiotic nucleic acids (XNAs). We have isolated fully modified 2\u2032-O-methyl-ribose-1,5-anhydrohexitol nucleic acid (MeORNA-HNA) aptamers targeting the rat vascular endothelial growth factor 164 (rVEGF164). Three sequences have been identified that interact with the target protein with affinities in the low-nanomolar range and HNA modifications appeared to be mandatory for their tight binding. The evolution of these XNA aptamers was accomplished using an in vitro selection procedure starting from a fully sugar-modified library containing a 20mer 2\u2032-OMe-ribonucleotide region followed by a 47mer HNA sequence. The high binding affinity and selectivity of the selected aptamers were confirmed by several methods including gel-shift, fluorescence polarisation, and enzyme-linked oligonucleotide assays. The isolated HNA ligands exhibited higher specificity to the rVEGF164 and human VEGF165 isoforms compared to rat VEGF120, while very low binding efficiencies were observed to streptavidin and thrombin. Furthermore, it was clearly demonstrated that the resulting aptamers possessed a superior stability to degradation in human serum and DNase I solutions