Simple Metals at High Pressure

In this lecture we review high-pressure phase transition sequences exhibited by simple elements, looking at the examples of the main group I, II, IV, V, and VI elements. General trends are established by analyzing the changes in coordination number on compression. Experimentally found phase transitions and crystal structures are discussed with a brief description of the present theoretical picture.Comment: 22 pages, 4 figures, lecture notes for the lecture given at the Erice course on High-Pressure Crystallography in June 2009, Sicily, Ital

Structure stability in the simple element sodium under pressure

The simple alkali metal Na, that crystallizes in a body-centred cubic structure at ambient pressure, exhibits a wealth of complex phases at extreme conditions as found by experimental studies. The analysis of the mechanism of stabilization of some of these phases, namely, the low-temperature Sm-type phase and the high-pressure cI16 and oP8 phases, shows that they satisfy the criteria for the Hume-Rothery mechanism. These phases appear to be stabilized due to a formation of numerous planes in a Brillouin-Jones zone in the vicinity of the Fermi sphere of Na, which leads to the reduction of the overall electronic energy. For the oP8 phase, this mechanism seems to be working if one assumes that Na becomes divalent metal at this density. The oP8 phase of Na is analysed in comparison with the MnP-type oP8 phases known in binary compounds, as well as in relation to the hP4 structure of the NiAs-type

The Representation of the Image of Russia in Foreign National Mass Media Discourse

This article focuses on the representation of the image of Russia in the discourse of foreign media (2014–2020). Taking into account the definition of the image of the state as a special concept, the article claims the lexeme «Russia», as well as the identities associated with this image in political and mass-information discourse. This concept contains historical, metaphorical, evaluative, ethnocultural and associative layers. Based on scientific  research on the problems of media discourse, image-formation, associations, and using the methods of critical discourse and conceptual metaphorical analysis, the article reveals the range of means of reaching the concept of «Russia» used by the media. Discourse depends on grammar, semiotics, semantics, structure and argumentation,  therefore it is important to answer the questions: how do «they» speak about «us» and how is the image of «us» formed in text or speech? To achieve the goal, we had content analysis of massmedia and had the associative  experimental technique too. These tools demonstrate the ideological values of the discourse in question and the associations that it forms in the minds of people. The paper suggests that the scheme of analysis of the image of state in the political mass media discourse, offered in it, can be applied to the investigation of images of other states

Origin of complex crystal structures of elements at pressure

We present a unifying theory for the observed complex structures of the sp-bonded elements under pressure based on nearly free electron picture (NFE). In the intermediate pressure regime the dominant contribution to crystal structure arises from Fermi-surface Brillouin zone (FSBZ) interactions - structures which allow this are favoured. This simple theory explains the observed crystal structures, transport properties, the evolution of internal and unit cell parameters with pressure. We illustrate it with experimental data for these elements and ab initio calculation for Li.Comment: 4 pages 5 figure

Approaches to the construction of simulation model of the process optimization of rare plants microclonal propagation

The authors present approaches to constructing an imitation model for the optimization of the process of rare plants microclonal reproduction (on the example of the Belgorod region), which allow to identify the most effective ways of explants sterilization, to define the optimal composition of nutrient media for regenerants growth (tube plants) and growth regulators (phytohormones) for propagation of mini-plant

Evidence of local superconductivity in granular Bi nanowires fabricated by electrodeposition

An unusual enhancement of resistance (i.e., superresistivity) below a certain characteristic temperature Tsr was observed in granular Bi nanowires. This superresistive state was found to be dependent on the applied magnetic field (H) as well as the excitation current (I). The suppression of Tsr by magnetic field resembles that of a superconductor. The observed superresistivity appears to be related to the nucleation of local superconductivity inside the granular nanowire without long-range phase coherence. The phenomenon is reminiscent of the Bose-insulator observed previously in ultra thin two-dimensional (2D) superconducting films and 3D percolative superconducting films.Comment: 11 pages, 5 figures. submitted to PR

Breeding of Vicia faba L. in relation to drought resistance

The Yu.N. Kurkina field method was used to determine the drought tolerance of bean plants. An analysis of the totality of ecological and morphological traits of forage bean varieties of different origins revealed varieties with pronounced xeromorphicity with low plant heights and narrow leaves. The varieties with high drought resistance have been identifie

Effect of pressure on the Raman modes of antimony

The effect of pressure on the zone-center optical phonon modes of antimony in the A7 structure has been investigated by Raman spectroscopy. The A_g and E_g frequencies exhibit a pronounced softening with increasing pressure, the effect being related to a gradual suppression of the Peierls-like distortion of the A7 phase relative to a cubic primitive lattice. Also, both Raman modes broaden significantly under pressure. Spectra taken at low temperature indicate that the broadening is at least partly caused by phonon-phonon interactions. We also report results of ab initio frozen-phonon calculations of the A_g and E_g mode frequencies. Presence of strong anharmonicity is clearly apparent in calculated total energy versus atom displacement relations. Pronounced nonlinearities in the force versus displacement relations are observed. Structural instabilities of the Sb-A7 phase are briefly addressed in the Appendix.Comment: 10 pages, 8 figure

Инструмент для горячего прессования металлических полых заготовок

Инструмент содержит контейнер, перекрытый с одного торца матрицей и снабженный соосно расположенным полым пуансоном, контактирующим с пресс-шайбой, соосно расположенную иглу, располагающуюся в полости пуансона, а также средство нагрева иглы. Отличается тем, что средство нагрева иглы дополнительно содержит нагревающую втулку, выполненную в виде стакана с днищем, обращенным в сторону матрицы, и размещаемую в полости контейнера, причем в полости нагревающей втулки размещается игла. Нагревающая втулка выполнена из стали. Технический результат от применения устройства заключается в расширении технологических возможностей