Pressure-induced phase transition of Bi2Te3 into the bcc structure

The pressure-induced phase transition of bismuth telluride, Bi2Te3, has been studied by synchrotron x-ray diffraction measurements at room temperature using a diamond-anvil cell (DAC) with loading pressures up to 29.8 GPa. We found a high-pressure body-centered cubic (bcc) phase in Bi2Te3 at 25.2 GPa, which is denoted as phase IV, and this phase apperars above 14.5 GPa. Upon releasing the pressure from 29.8 GPa, the diffraction pattern changes with pressure hysteresis. The original rhombohedral phase is recovered at 2.43 GPa. The bcc structure can explain the phase IV peaks. We assumed that the structural model of phase IV is analogous to a substitutional binary alloy; the Bi and Te atoms are distributed in the bcc-lattice sites with space group Im-3m. The results of Rietveld analysis based on this model agree well with both the experimental data and calculated results. Therefore, the structure of phase IV in Bi2Te3 can be explained by a solid solution with a bcc lattice in the Bi-Te (60 atomic% tellurium) binary system.Comment: 12 pages, 5 figure

Adhesive coatings based on aligned arrays of carbon nanostructures

This work was financially supported by Russian Foundation for Basic Research (projects 16-29-14023 and 18-32-00652) and Internal grant of the Southern Federal University (project VnGr-07/2017-26)

The role of aTp-dependent chromatin remodeling factors in chromatin assembly in vivo

Chromatin assembly is a fundamental process essential for chromosome duplication subsequent to DNA replication. In addition, histone removal and incorporation take place constantly throughout the cell cycle in the course of DNA-utilizing processes, such as transcription, damage repair or recombination. In vitro studies have revealed that nucleosome assembly relies on the combined action of core histone chaperones and ATP-utilizing molecular motor proteins such as ACF or CHD1. Despite extensive biochemical characterization of ATP-dependent chromatin assembly and remodeling factors, it has remained unclear to what extent nucleosome assembly is an ATP-dependent process in vivo. Our original and published data about the functions of ATP-dependent chromatin assembly and remodeling factors clearly demonstrated that these proteins are important for nucleosome assembly and histone exchange in vivo. During male pronucleus reorganization after fertilization CHD1 has a critical role in the genomescale, replication-independent nucleosome assembly involving the histone variant H3.3. Thus, the molecular motor proteins, such as CHD1, function not only in the remodeling of existing nucleosomes but also in de novo nucleosome assembly from DNA and histones in vivo. ATP-dependent chromatin assembly and remodeling factors have been implicated in the process of histone exchange during transcription and DNA repair, in the maintenance of centromeric chromatin and in the loading and remodeling of nucleosomes behind a replication fork. Thus, chromatin remodeling factors are involved in the processes of both replication-dependent and replication-independent chromatin assembly. The role of these proteins is especially prominent in the processes of large-scale chromatin reorganization; for example, during male pronucleus formation or in DNA repair. Together, ATP-dependent chromatin assembly factors, histone chaperones and chromatin modifying enzymes form a “chromatin integrity network” to ensure proper maintenance and propagation of chromatin landscape

Fouilles de la cité de Taman : de l’antique Hermonassa à la Tamatarkha médiévale

Hermonassa est située sur la côte méridionale de la baie de Taman. Elle occupe aujourd’hui une surface de près de 16 ha répartie sur deux niveaux. Des recherches archéologiques sont actuellement menées dans la moitié ouest, déclarée protégée et libre de toute construction moderne. La ville d’Hermonassa apparaît au plus tard à la fin du VIe s. av. J.-C. et subsiste presque sans interruption durant les époques historiques successives, changeant seulement de taille et de nom. Au IVe s. av. J.-C., elle intègre l’État du Bosphore Cimmérien en même temps que la Sindiké. Durant les premiers siècles de notre ère, des liens commerciaux entre le Bosphore et les tribus alanes sont entretenus via Hermonassa. L’histoire antique de la ville d’Hermonassa s’achève avec l’arrivée des nomades. Dès le milieu du IIIe siècle, la ville subit l’invasion des Goths, alors que durant la seconde moitié du IVe siècle, l’arrivée des Huns ne cause pas de destruction notable à la ville. L’influence de Byzance commence à se faire sentir à Hermonassa aux Ve et IVe siècles. L’histoire médiévale de la ville de Tamatarkha débute lorsqu’elle passe sous la coupe des Khazars au VIIe siècle. Il se peut que Tamatarkha ait fait partie, avec d’autres centres urbains de Tauride, du système de « dyarchie » byzantino-khazare. Ce système de rapports réciproques s’est poursuivi jusqu’au deuxième tiers du IXe siècle

Internet communications of military personnel and their families in social networks as an object of digital sociology’s study

The conceptual, methodological and technological approaches to organization of sociological study of communicative Internet activity ofmilitary personnel in a social networks, the specific behavior in accordance with the requirements as to members ofthe militaryprofessional corporate group of people in the information-communication network “Internet” have been considered. The constitutional norms that restrict the rights of military personnel in various spheres of social interaction, as well as the norms of domestic legislation that specify these requirements have been analyzed. The described type of Internet communication has been characterized as an object of study of military sociology at various levels: general scientific, private scientific and empirical. The author's found a connection between a considered problem with the concepts of “information society”, “digital society”, “digital economy” and virtualization of social relations, as well as the concept of “human rights”. The general tendency to include of various countries confrontation with a likely enemy in the virtual space in the military- doctrinal documents has been revealed. At the same time, ensuring military security involves protecting the minds of their military personnel from negative impact, including in the case of their use of services in the Internet space. The experience of other countries in regulating the social activity of military personnel and their families in the Internet has been described. Based on the generalization of social practice, conclusions from the risk analysis of the participation of subjects of military professional activity in social networks, which is associated with threats to determine the location of military units, plans for the movement of troops, weapons, staff and personnel, that is, information constituting a military secret, have been presented. A list of other threats related to social communications of military personnel and their families in the virtual space also has been adduced. The ways to reduce the risk of negative impact on military members and their families participate in social networks and other Internet communications by implementing legal, organizational and outreach activities have been presented

Vertically Aligned Carbon Nanotubes Production by PECVD

This chapter presents the results of experimental studies of the PECVD technological mode parameters’ influence on the formation of catalytic centers and carbon nanotubes’ (CNTs’) growth processes. This chapter also presents the ability to regulate the growth parameter for the controlled production of CNTs with the required geometric parameters, properties, and growth mechanisms. The results of experimental studies of the heating temperature and activation time effects on the catalytic center formation will be presented. This chapter also shows the effects of growth temperature, heating rate, and the activation time on the geometric and structural parameters of the carbon nanotubes. Experimental studies were carried out with the use of AFM, SEM, TEM, and EXAFS techniques. The results can be used in the development of technological processes for creating ultrafast energy-efficient electronic component base with carbon nanostructures, particularly nanoelectromechanical switches, flexo- and piezoelectric generators, gas sensors, and high-performance emitters

Application of Probe Nanotechnologies for Memristor Structures Formation and Characterization

This chapter presents the results of experimental studies of the formation and investigation of the memristors by probe nanotechnologies. This chapter also perspectives and possibilities of application of local anodic oxidation and scratching probe nanolithography for the manufacture of memristors based on titanium oxide structures, nanocrystalline ZnO thin film, and vertically aligned carbon nanotubes. Memristive properties of vertically aligned carbon nanotubes, titanium oxide, and ZnO nanostructures were investigated by scanning probe microscopy methods. It is shown that nanocrystalline ZnO films manifest a stable memristor effect slightly dependent on its morphology. Titanium oxide nanoscale structures of different thicknesses obtained by local anodic oxidation demonstrate a memristive effect without the need to perform any additional electroforming operations. This experimentally confirmed the memristive switching of a two-electrode structure based on a vertically aligned carbon nanotube. These results can be used in the development of designs and technological processes of resistive random access memory (ReRAM) units based on the memristor devices

Scanning Probe Techniques for Characterization of Vertically Aligned Carbon Nanotubes

This chapter presents the results of experimental studies of the electrical, mechanical and geometric parameters of vertically aligned carbon nanotubes (VA CNTs) using scanning probe microscopy (SPM). This chapter also presents the features and difficulties of characterization of VA CNTs in different scanning modes of the SPM. Advanced techniques for VA CNT characterization (the height, Young’s modulus, resistivity, adhesion and piezoelectric response) taking into account the features of the SPM modes are described. The proposed techniques allow to overcome the difficulties associated with the vertical orientation and high aspect ratio of nanotubes in determining the electrical and mechanical parameters of the VA CNTs by standard methods. The results can be used in the development of diagnostic methods as well as in nanoelectronics and nanosystem devices based on vertically aligned carbon nanotubes (memory elements, adhesive structures, nanoelectromechanical switches, emission structures, etc.)

In vitro antifungal activity of metal complexes of a quaternized chitosan derivative with copper ions

© 2017, Pleiades Publishing, Ltd. Antifungal activity of synthetic metal complexes of quaternized N-(propyl) chitosan derivatives with Сu(II) against yeastlike (Saccharomyces cereviseae, Rodothorula rubra, and Candida albicans) and mycelial fungi (Fusarium oxysporum, Alternaria alternata, Cladosporium herbarum) was studied. In vitro application (at 250‒500 μg/mL) of the metal complex of quaternized N-(propyl) derivative of low-molecular chitosan with 53% substitution and 1.3% copper ions proved efficient against F. оxysporum, one of ten most common fungal plant pathogens. Water-soluble quaternized N-(propyl) chitosan derivatives with 40−58% degree of substitution were synthesized using glycidyltrimethylammonium chloride under optimally adjusted conditions. Metal complexes of the chitosan derivative with 53% degree of substitution with Сu(II) ions were obtained by dialysis. The quantity of copper ions in the metal complexes was determined by atomic emission spectrometry. The structure of chitosan derivatives was confirmed by spectral analysis (IR, 1 H NMR)

Amperometric detection of hydroxypurines at an electrode modified with a composite based on mixed-valence ruthenium and cobalt oxides in flow injection analysis

© 2017, Pleiades Publishing, Ltd.A composite material based on mixed-valence ruthenium and cobalt oxides, electrodeposited on the surface of a screen printed electrode, exhibits high catalytic activity in the electrooxidation of uric acid, xanthine, and hypoxanthine. Catalysis manifests itself as a decrease in the substrate oxidation overvoltage and an increase in current at the potential of modifier oxidation. A method is proposed for the simultaneous amperometric detection of two-component systems uric acid–xanthine, xanthine–hypoxanthine, and uric acid–hypoxanthine using a screen printed electrode with two working electrodes modified by this composite. The dependence of the analytical signal on the concentration of analytes is linear in the range 5 × 10–8 to 5 × 10–3 M for uric acid and xanthine and from 5 × 10–7 to 5 × 10–3 M for hypoxanthine