Petro fabric characteristics of olivine from xenoliths, peridotites, and basalts (from Canary Islands, Kuznetsk Alatau and Yoko-Dovyren Massif)

This paper presents results of study of petro fabric specific characteristics of olivine from xenoliths, peridotites, and basalts (from Canary Islands, Kuznetsk Alatau and Yoko-Dovyren Massif

Sedimentary deposits and petrography of the basalts of the island of Tenerife of the Canary archipelago (Spain)

The article is devoted to the study of sedimentary deposits on the slopes of the Teide volcano and petrography of the volcanic rocks of the island of Tenerife of the Canary archipelago (Spain). A description of the sediments, which are presented on the island's territory, and an analysis of the features of the material composition of rocks are given

Application of hydrogenation to low-temperature cleaning of the Si(001) surface in the processes of molecular-beam epitaxy: Investigation by STM, RHEED and HRTEM

Structural properties of the clean Si(001) surface obtained as a result of low-temperature (470--650C) pre-growth annealings of silicon wafers in a molecular-beam epitaxy chamber have been investigated. To decrease the cleaning temperature, a silicon surface was hydrogenated in the process of a preliminary chemical treatment in HF and NH_4F aqueous solutions. It has been shown that smooth surfaces composed by wide terraces separated by monoatomic steps can be obtained by dehydrogenation at the temperatures > 600C, whereas clean surfaces obtained at the temperatures < 600C are rough. It has been found that there exists a dependence of structural properties of clean surfaces on the temperature of hydrogen thermal desorption and the process of the preliminary chemical treatment. The frequency of detachment/attachment of Si dimers from/to the steps and effect of the Ehrlich-Schwoebel barrier on ad-dimer migration across steps have been found to be the most probable factors determining a degree of the resultant surface roughness.Comment: 8 pages, 8 figures; version accepted to J. Appl. Phy

Where is the consumer center of St. Peterburg?

In an urban economy, the distribution of people and real estate prices depends on the location of the central business district of a city. As distance from the city center increases, both prices and population density diminish, for travel costs increase in terms of time and money. As manufacturing gradually leaves the cities, the importance of consumer amenities as attractors of population to the urban areas increases. The role of a business center is being replaced by the consumer center. In this paper, we identify the location of the consumer center of St. Petersburg - the second largest city in Russia and its former capital. For this purpose using the data from open sources in the Internet regarding the location of many different types of urban amenities, the indices of their spatial density are computed. Using the weights based on coefficients of spatial variation and survey-based weights, the individual indices are aggregated to two general centrality indices. Their unique maxima correspond to the city center of St. Petersburg, which is located on Nevsky prospekt, between Fontanka river and Liteinyi prospekt

Experience of universities in practice-oriented training personnel for high-tech enterprises

Different options have been considered of work-based learning (WBL) in Russian and foreign universities. Special attention is given to the variant of PBL - project learning (PL) on training bachelors. Basic concepts and principles have been discussed dealing with the organization of PL developed by Aalborg University - one of the founders of this teaching technique. Тhe advisability is shown of organizing special courses of introduction to project learning in the first two semesters.peer-reviewe

Analysis of the problems of formation of calligraphic skills in primary school pupils

The article presents the results of a study of calligraphic writing skills in primary school pupils of the general education school and analyzes problems with the acquisition of these skills.В статье представлены результаты исследования каллиграфического навыка письма у обучающихся начальных классов общеобразовательной школы, проведен анализ трудностей овладения данным навыком

Impact of High-Temperature, High-Pressure Synthesis Conditions on the Formation of the Grain Structure and Strength Properties of Intermetallic Ni[3]Al

The impact of the preliminary load on 3Ni+Al powder mixture and the impact of the duration of the delay in application of compacting pressure to synthesis product under the conditions of continuous heating of the mixture up to its self-ignition on the grain size and strength properties of the synthesized Ni[3]Al intermetallide material have been studied. The grain structure of the intermetallide synthesized under pressure was studied by means of metallography, transmission electron microscopy and EBSD analysis, with the dependence of ultimate tensile strength on the grain size in the synthesized intermetallide having been investigated at room temperature and at temperatures up to 1000°С. It is shown that an increase in the pressure preliminarily applied to the initial mixture compact results in reduced grain size of the final intermetallide, whereas an increase in pre-compaction time makes the grain size increased. A decrease in the grain size increases the ultimate tensile strength of the intermetallide. The maximum value of the ultimate tensile strength in the observed anomalous temperature dependence of this strength exhibits a shift by 200°С toward higher temperatures, and the ultimate strength of the synthesized intermetallide at 1000°С increases roughly two-fold