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The article discusses the problems of distance learning. They are relevant due to the increase in the demand for continuing education, the development of teaching methods for humanities, particularly history. Distance learning in history is related to the task of shaping historical thinking. The purpose of the article is to study the attitude of university lecturers and students towards distance learning in history classes. The empirical basis of the article was the results of a sociological survey conducted among the students of Togliatti State University in 2021 (N=287).The analysis of the survey results shows that the students’ views on distance learning in history are divided. About half of the students are positive about this mode of study, and the other half are negative. There were more respondents among young males, as well as technical students, who described the history distance learning sessions positively. The students are attracted by the extensive use of Internet sources and visual materials. Among girls, as well as humanities students, there are more of those who have a negative attitude towards distance learning in history. The negative aspects are related to technical problems, as well as the lack of direct communication with the teacher. The respondents who do not have a high level of interest in studying history are more likely to express a positive attitude towards distance learning. In contrast, the respondents who are interested in history are more likely to have a negative attitude towards this form of training.

Natural aluminosilicates are promising sorbents that can be used to separate and isolate biologically active substances, namely vitamins. Hydrochloride pyridoxine (vitamin B6) is an important biologically active compound necessary for the normal functioning of the body. This article describes the investigation of absorption regularities of pyridoxine hydrochloride on the glauconite. Clay aluminosilicate, i.e. glauconite with a layered structure (from south-west of the Voronezh anteclise) was chosen as the subject for the study. Its phase composition is represented by mixed-layer minerals of illite-smectite with 20:80 ratio of layers and a high iron level. Its interlayer space has water molecules and K+, Mg2+ and Ca2+ exchangeable cations. The study of equilibrium in glauconite (0.02–0.06 mm fraction), i.e. aqueous solution of vitamin B6, was carried out at a temperature of 295 K under static conditions by using variable concentrations. The interval for the vitamin concentrations within 0.02 and 7.25 mmol/dm3 in the pH solution was 3.50–3.94, where pyridoxine hydrochloride was mainly present in the solution in the form of cations. Absorption regularities of pyridoxine hydrochloride on the glauconite were identifi ed and explained. To conduct a quantitative description of sorption equilibrium in the interval of concentrations that lead to the formation of the vitamin monolayer the linearized equations of Langmuir, Freundlich, Redlich–Peterson models were used. Whereas the Brunauer–Emmett–Teller (BET) theory was used to describe the isotherm as a whole. It was established that the sorption process involves the localization of pyridoxine cations at the negatively charged centres of glauconite which results from ion exchanges with extra framework cations and the formation of associates. Pyridoxine sorption caused by ion exchange can be described with high probability by the Langmuir model. The multi-molecular nature of the sorption and the increase in the solution concentration determine the formation of pyridoxine associates caused by the formation of hydrogen bonds and π-π interactions in the pyridine ring. The equilibrium coeffi cient for the pyridoxine distribution in the glauconite structure was calculated. The increase in concentration of the solution leads to the sharp decrease in the formation of the monolayer. The polymolecular sorption of the vitamin is characterized by a slight change in the distribution coeffi cient.

This article describes a method for analyzing hierarchies; identifies the problems with inconsistent judgments. The proof is given that the most effective tool allowing one to make the right decisions with inconsistencies is the introduction of the eigenvector on environmental planning and management. The Analytic Hierarchy Process (AHP) is a method for decision making, which includes qualitative factors. In this method, ratio scales are obtained from ordinal scales, which are derived from individual judgments for qualitative factors using the pairwise comparison matrix. This paper describes the applicability of a multicriteria decision-making method, specifically, the analytic network process.

Changes in the surface microgeometry of multilayer graphene films, as a result of hydrogen adsorption (1% mass.), have been examined by the method of low-temperature fractal sorption of nitrogen. It is established that hydrogen atmosphere treatment leads to the significant development of graphene surface and lowers the first layer heat adsorption from 289 down to 260J/kg. There have been found out as well the overall mesopores concentration growth and pore size distribution function broadening. At that, the surface fractal dimension value has grown from 2,52 up to 2,67, which is to give us an evidence of the surface chaotization as a result of hydrogen withdrawal into the atmosphere and the graphene surface erosion.

This review article is focused on the progress made in the synthesis of 5'-α-P-modified nucleoside triphosphates (α-phosphate mimetics). A variety of α-P-modified nucleoside triphosphates (NTPαXYs, Y = O, S; X = S, Se, BH 3 , alkyl, amine, N-alkyl, imido, or others) have been developed. There is a unique class of nucleoside triphosphate analogs with different properties. The main chemical approaches to the synthesis of NTPαXYs are analyzed and systematized here. Using the data presented here on the diversity of NTPαXYs and their synthesis protocols, it is possible to select an appropriate method for obtaining a desired α-phosphate mimetic. Triphosphates' substrate properties toward nucleic acid metabolism enzymes are highlighted too. We reviewed some of the most prominent applications of NTPαXYs including the use of modified dNTPs in studies on mechanisms of action of polymerases or in systematic evolution of ligands by exponential enrichment (SELEX). The presence of heteroatoms such as sulfur, selenium, or boron in α-phosphate makes modified triphosphates nuclease resistant. The most distinctive feature of NTPαXYs is that they can be recognized by polymerases. As a result, S-, Se-, or BH 3 -modified phosphate residues can be incorporated into DNA or RNA. This property has made NTPαXYs a multifunctional tool in molecular biology. This review will be of interest to synthetic chemists, biochemists, biotechnologists, or biologists engaged in basic or applied research.

Detection of the Kirsten rat sarcoma gene ( KRAS ) mutational status is an important factor for the treatment of various malignancies. The most common KRAS -activating mutations are caused by single-nucleotide mutations, which are usually determined by using PCR, using allele-specific DNA primers. Oligonucleotide primers with uncharged or partially charged internucleotide phosphate modification have proved their ability to increase the sensitivity and specificity of various single nucleotide mutation detection. To enhance the specificity of single nucleotide mutation detection, the novel oligonucleotides with four types of uncharged and partially charged internucleotide phosphates modification, phosphoramide benzoazole (PABA) oligonucleotides (PABAO), was used to prove the concept on the KRAS mutation model. The molecular effects of different types of site-specific PABA modification in a primer or a template on a synthesis of full-length elongation product and PCR efficiency were evaluated. The allele-specific PCR (AS-PCR) on plasmid templates showed a significant increase in analysis specificity without changes in Cq values compared with unmodified primer. PABA modification is a universal mismatch-like disturbance, which can be used for single nucleotide polymorphism discrimination for various applications. The molecular insights of the PABA site-specific modification in a primer and a template affect PCR, structural features of four types of PABAO in connection with AS-PCR results, and improvements of AS-PCR specificity support the further design of novel PCR platforms for various biological targets testing.

In this work, we present new oligonucleotide derivatives containing inter-nucleotide N -benzimidazole, N -benzoxazole, N -benzothiazole, and 1,3-dimethyl- N -benzimidazole (benzoazoles) phosphoramide groups. These modifications were introduced via the Staudinger reaction with appropriate azides during standard automated solid-phase oligonucleotide synthesis. The principal structural difference between the new azido modifiers and those already known is that they are bulk heterocyclic structures, similar to purine nucleoside bases. Modified oligonucleotides with one and two modifications at different positions and multiple modified heteronucleotide sequences were obtained with high yields. The possibility of multiple modifications in the process of automatic DNA synthesis is fundamental and critical for further application of our oligonucleotide derivatives. Initial studies on the properties of new oligonucleotides were carried out. The stability of the oligodeoxyribonucleotide duplex containing phosphoramide groups of N -benzoazoles with complementary DNA or RNA is slightly lower than that of native complexes., Competing Interests: The authors declare no competing financial interest., (© 2022 The Authors. Published by American Chemical Society.)

Efficient protocols were developed for the synthesis of a new compounds - nucleoside 5'-α-iminophosphates using the Staudinger reaction. These substances are alpha-phosphate mimetic nucleotide in which an oxygen atom is replaced by a corresponding imino (=N-R)-group. Various 5'-iminomonophosphates of nucleosides were obtained. A chemical method for the synthesis of triphosphate derivatives based on the iminomonophosphates has been designed. Thymidine 5'-(1,3-dimethylimidazolidin-2-ylidene)-triphosphate (ppp(DMI)T) was synthesized, its hydrolytic stability and substrate properties in relation to some DNA polymerases was firstly studied. It was shown that ppp(DMI)T can serve as substrate for enzyme catalyzed template-independent DNA synthesis by human terminal deoxynucleotidyltransferase TdT., (Copyright © 2022 Elsevier Inc. All rights reserved.)

SiO 2 nanoparticles were used as a transport system for cellular delivery of phosphorylated 2',3'-dideoxyuridine to increase its anticancer potency. This data set is related to the research article entitled "2',3'-Dideoxyuridine triphosphate conjugated to SiO 2 nanoparticles: synthesis and evaluation of antiproliferative activity" (Vasilyeva et al., 2018) [1]. It includes a protocol for the synthesis of 2',3'-dideoxyuridine-5'-{N-[4-(prop-2-yn-1-yloxy)butyl]-γ-amino}-triphosphate, its identification by NMR, IR and ESI-MS, experimental procedure of covalent attachment to SiO 2 nanoparticles with via Cu-catalyzed click-chemistry, experimental data on chemical stability of the conjugate at different pH values and cytotoxicity assessment of antiproliferative effect of the conjugate.

A conjugate of triphosphorylated 2',3'-dideoxyuridine (ddU) with SiO 2 nanoparticles was obtained via the CuAAC click chemistry between a γ-alkynyl ddU triphosphate and azido-modified SiO 2 nanoparticles. Assessment of cytotoxicity in human breast adenocarcinoma MCF7 cells demonstrated that ddU triphosphate conjugated to SiO 2 nanoparticles exhibited a 50% decrease in cancer cell growth at a concentration of 183 ± 57 µg/mL, which corresponds to 22 ± 7 µM of the parent nucleotide, whereas the parent nucleoside, nucleotide and alkynyl triphosphate precursor do not show any cytotoxicity. The data provide an example of remarkable potential of novel conjugates of SiO 2 nanoparticles with phosphorylated nucleoside analogues, even those, which have not been used previously as therapeutics, for application as new anticancer agents., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Fluorescently labeled DNA to study protein-DNA interactions was synthesized using the Cu(I)-catalysed cycloaddition (CuAAC) reaction. For this purpose, a new azido-containing fluorophore based on the naphtho[1,2,3-cd]indol-6(2H)-one derivative was obtained. The fluorescent properties of naphtho[1,2,3-cd]indol-6(2H)-one derivatives and labeled DNA were studied. The new fluorescent DNA conjugate was shown to be a useful tool to study complex mechanisms of protein-DNA interactions., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Conjugates of phosphorylated dideoxynucleoside antiviral drugs dideoxycytidine (zalcitabine) and lamivudine with SiO 2 nanoparticles were obtained via the copper(I)-catalyzed azide-alkyne cycloaddition (CuAAC) click chemistry between a nucleoside triphosphate containing an alkynyl group at the γ-phosphate or azidothymidine triphosphate and SiO 2 nanoparticles containing alkyl azide or alkynyl groups, respectively. 4-(Prop-2-yn-1-yloxy)butylamino group has been attached to the γ-phosphate group of dideoxycytidine (zalcitabine) and lamivudine 5'-triphosphates via the phosphoramidate linkage. New compounds were shown to be potent killers of human colon carcinoma cells. Anti-HIV activity of the conjugates was demonstrated as well. The conjugates of phosphorylated lamivudine and dideoxycytidine (zalcitabine) showed higher potency than the parent nucleosides. The conjugate of phosphorylated azidothymidine was less active against HIV-1 than the parent nucleoside probably because of the replacement of its 3'-azido group by 1,2,3-triazole ring. These results show an opportunity for using SiO 2 nanoparticles as a transport for delivering phosphorylated nucleosides to cells in order to increase their efficiency as antiviral and anticancer drugs., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Efficient protocols based on Cu(I)-catalyzed azide-alkyne cycloaddition were developed for the synthesis of conjugates of pyrrole-imidazole polyamide minor groove binders (MGB) with fluorophores and with triplex-forming oligonucleotides (TFOs). Diverse bifunctional linkers were synthesized and used for the insertion of terminal azides or alkynes into TFOs and MGBs. The formation of stable triple helices by TFO-MGB conjugates was evaluated by gel-shift experiments. The presence of MGB in these conjugates did not affect the binding parameters (affinity and triplex stability) of the parent TFOs.

Recent years have seen a resurgence of interest in crystalline silicon Schottky junction solar cells distinguished by the use of low density of electronic states (DOS) nanocarbons (nanotubes, graphene) as the metal contacting the Si. Recently, unprecedented modulation of the power conversion efficiency in a single material system has been demonstrated in such cells by the use of electronic gating. The gate field induced Fermi level shift in the low-DOS carbon serves to enhance the junction built-in potential, while a gate field induced inversion layer at the Si surface, in regions remote from the junction, keeps the photocarriers well separated there, avoiding recombination at surface traps and defects (a key loss mechanism). Here, we extend these results into the third dimension of a vertical Si nanowire array solar cell. A single wall carbon nanotube layer engineered to contact virtually each n-Si nanowire tip extracts the minority carriers, while an ionic liquid electrolytic gate drives the nanowire body into inversion. The enhanced light absorption of the vertical forest cell, at 100 mW/cm(2) AM1.5G illumination, results in a short-circuit current density of 35 mA/cm(2) and associated power conversion efficiency of 15%. These results highlight the use of local fields as opposed to surface passivation as a means of avoiding front surface recombination. A deleterious electrochemical reaction of the silicon due to the electrolyte gating is shown to be caused by oxygen/water entrained in the ionic liquid electrolyte. While encapsulation can avoid the issue, a nonencapsulation-based approach is also implemented.

A system for delivery of analogues of AZT-triphosphates (AZT*TP) based on SiO₂ nanoparticles was proposed. For this purpose, a simple and versatile method was developed for the preparation of SiO₂∼dNTP conjugates using the 'click'-reaction between AZTTP and premodified nanoparticles containing the alkyne groups. The substrate properties of SiO₂∼AZT*TP were tested using Klenow fragment and HIV reverse transcriptase. The 3'-triazole derivatives of thymidine triphosphate being a part of the SiO₂∼AZT*TP nanocomposites were shown to be incorporated into the growing DNA chain. It was shown by confocal microscopy that the proposed SiO₂∼AZT*TP nanocomposites penetrate into cells. These nanocomposites were shown to inhibit the reproduction of POX and Herpes viruses at nontoxic concentrations., (Copyright © 2015 Elsevier Ltd. All rights reserved.)