Study of the Temperature Dependence of a Carbidized Layer Formation on the Tungsten Surface Under Plasma Irradiation

The paper considers a method of tungsten surface carbidization using a beam-plasma discharge (BPD), which was implemented in a plasma-beam installation (PBI). The advantage of this method is to create conditions for chemical reactions and physical processes as close as possible to those possible in thermonuclear installations. The BPD makes it possible to generate plasma using different working gases. Methane was used as a plasma-forming gas. The working gas pressure in a chamber was (1,3-1,4)·10-1 Pa. The temperature dependence of the carbidized layer formation on the tungsten surface under plasma irradiation was determined in the temperature range of 700-1700 °C. The formation of tungsten carbides in surface layers was confirmed by SEM and X-ray diffraction analysis. It was found that interaction between tungsten and methane in a wide temperature range can proceed with simultaneous or sequential formation of the carbide phases W2C and WC.

SYNTHESIS OF 3,3´-(1,4-PHENYLENE)BIS(1-(4-R-PHENYL)-5-PHENYL-5,6-DIHYDRO-1,2,4,5-TETRAZINIUM) PERCHLORATES

A series of 3,3'-(1,4-phenylene)bis(1-4-R-phenyl)-5-phenyl-5,6-dihydro-1,2,4,5-tetrazinium) perchlorates containing hydrogen, methyl, bromio, methoxy, acetyl and nitro groups (R = H, Me, Br, OMe, COMe, NO2) as substituents were obtained as a result of a three-stage synthesis from terephthalic aldehyde. The synthesis of tetrazinium salts was carried out by reaction of the corresponding formazans with formalin in the presence of perchloric acid in dioxane. Formazans were obtained by reaction of terephthalic aldehyde phenylhydrazone with arenediazonium tosylates in a mixture of DMF and pyridine. The usage of arenediazonium tosylates made it possible to extremely simplify the segregation and purification of formazans. The phenylhydrazone was synthesized according to the standard procedure from terephthalic aldehyde and phenylhydrazine/hydrochloric acid in aqueous dioxane. The formazans and tetrazinium perchlorates were isolated in individual state and characterized by elemental analysis, IR, UV, 1H and 13C NMR spectroscopy data. The process of electrochemical reduction of tetrazinium perchlorates was studied using the method of cyclic voltammetry (CV). Thus, the CV curves of all salts in the cathode region contain two one-electron reduction peaks, which are related to the sequential formation of a radical cation and a biradical. It was found that electron-donating substituents (R = Me, OMe) in the aromatic ring at position 1 facilitate the reduction of tetrazinium cation, while electron-withdrawing substituents (R = COMe, NO2) hinder this process. On this basis, it was suggested that the corresponding bis-verdazyl radicals should be easily formed in the presence of electron-donating substituents in the aromatic ring at position 1. Thus, 3,3´-(1,4-phenylene)bis(1-(4-R-phenyl)-5-phenyl-5,6-dihydro-1,2,4,5-tetrazinium-1) perchlorates are perspective precursors of symmetric biradical systems based on verdazyl radicals.

An Analysis of the Compliance of the Structures of Relations of Objects of Classes on the Varieties of their Descriptions

The synthesis of latent features is considered in order to reduce the size of the space for describing objects of disjoint classes K1, K2. A condition is proposed for the sequential formation of feature sets X(h) I X(n), 2 ? h ? n for linear display of object descriptions from X(h) to R2. Latent features are synthesized from data obtained as a result of preprocessing the values of the initial features. Preprocessing is realized through normalization in [0,1] and data transformation that is invariant to the scales of feature measurements. The correspondence structures of objects in X(h) and R2 are investigated according to the results of data preprocessing and grouping. A measure of compliance of two structures of relations of objects in different features spaces is proposed. The measure of compliance is calculated by splitting the objects of classes into disjoint groups. When splitting into groups, the relation of connectedness of class objects by a defined set of hyper balls is used.

Synchronization of the neurons coupled with sequential developing electrical and chemical synapses

<abstract> <p>There is some evidence representing the sequential formation and elimination of electrical and chemical synapses in particular brain regions. Relying on this feature, this paper presents a purely mathematical modeling study on the synchronization among neurons connected by transient electrical synapses transformed to chemical synapses over time. This deletion and development of synapses are considered consecutive. The results represent that the transient synapses lead to burst synchronization of the neurons while the neurons are resting when both synapses exist constantly. The period of the transitions and also the time of presence of electrical synapses to chemical ones are effective on the synchronization. The larger synchronization error is obtained by increasing the transition period and the time of chemical synapses' existence.</p> </abstract>

Common interests of parents and adolescents

The article discusses the common interests of parents and adolescents, who have become significantly different in modern society with the advent of innovative technologies between the older and younger generations. The author analyzes the problem of underdeveloped forms of family leisure and take notice to the fact that in various types of leisure activities, the sequential formation of personal qualities of children such as independence, curiosity, organization, sociability, confidence, success and others is more effectively carried out. Family values are promoted by joint leisure, influencing the development of adolescents in socialization. The scientific works of scientists are analyzed, from which the conclusion about the common interests of adults and children follows. The types of family vacations at home and outside are consid it is worthwhile to form interests and traditions that unite adolescents and parents on the positive side. The author suggests synthesizing traditional and innovative forms of organizing family leisure activities in order to achieve common interests of parents and adolescents.

Jewelry and ornamental ammonites from the deposits of the Hauterivian stage of the Ulyanovsk Region: Mineral composition, gemological characteristics

Significant volumes of products from ammonites of jewelry and ornamental quality of the Ulyanovsk region are entering the Russian and world markets. Ammonites are associated with the Lower Cretaceous Hauterivian deposits and consist mainly of aragonite, calcite and pyrite. The walls and partitions of the ammonite shells retained the original aragonite composition. Also established inclusions of apatite, algodonite, pyrolusite, hematite, goethite, quartz, ferrihydrite, magnetite, uranium oxide, vernadite, todorokite, monazite, halloysite, plagioclase, kaolinite, glauconite, dolomite, graphite and organic matter. An important role in the formation of new mineral species was played by bacteria. Mineralization of undamaged ammonite chambers was carried out by the sequential formation of calcite and pyrite layers without metasomatic substitutions. The color of calcite layers is determined by the contents of Mn and Fe. Ammonites are characterized by high decorativeness and good technological characteristics; they can be mined in the coastal cliffs and the beach area of the river Volga without mining, without violating the environment.