Influence of the temperature of treatment of KU-1 quartz glass on the value of the elastic recovery of a microindentation imprint

The influence of the treatment temperature of KU-1 quartz glass on the value of the elastic recovery of the microindentation imprint of a Vickers diamond tetrahedral pyramid is studied. It is found that the value of the elastic recovery of the imprint’s diagonal and the fracture resistance of quartz glass upon microindentation varies depending on the preliminary thermal treatment. The obtained experimental results are compared with the data reported by other authors.     

Identification of the position of an equilibrium attitude of the International Space Station as a problem of stable matrix completion

For a discrete model of the angular motion of the International Space Station, using an onboard identification model, the problem of identification of the equilibrium attitude position is solved under the action of aerodynamic, gravitational, gyroscopic moments. It is shown that the convergence of the iteration process is determined by a choice of weight coefficients in the equations of the identification onboard model. In this paper, the possibility of finding numerical values of the weight coefficients by solving the problem of stable matrix completion is addressed. A symbolic method for solving the problem of stable matrix completion is proposed. Using this method, numerical values of the weight coefficients that provide fast convergence of the iteration search of an equilibrium attitude of the International Space Station are obtained.     

Rare and unique communities in the South of Western Siberia of the Bolshaya Sogra natural complex (Kislukhinsky state natural regional reserve,the Altaisky Krai,Russia)

The paper presents floristic and geo-botanical characteristics of rare forest ecosystems of the south of Western Siberia – spruce forests on the site of the Ob river ancient bed within the modern Bolshaya Sogra within the boundaries of the state natural reserve ‘Kislukhinsky’ (Altai region). Spruce forests here are at the edge of their spread in the West Siberian Plain conditions. There are over 300 species of vascular plants found in these spruce forests. Among them are plants that are typical of the mountain taiga associations of Russian Altai, as well as orchids, which have high species diversity. Spruce forest set of associations is also varied. The uniqueness of the described communities to the south of Western Siberia, the large number of rare and endangered plant species listed in the Red Books of different ranks, as well as the boreal forest species complex rare to the lowland wooded steppe, which has a relict character, all served as the basis for allocating a special protection area in the ‘Kislukhinsky’ reserve and attributing the studied spruce forests to the forests of high conservation value.     

Semiconductor lasers with asymmetric barrier layers: An approach to high temperature stability

A method for enhancing the temperature stability of injection lasers that is based on introducing asymmetric barrier layers on each side of the quantum-confined active region is suggested. The asymmetric barrier layers prevent electrons from escaping from the active region into the part of the waveguide region where holes are injected and prevent holes from escaping into the part of the waveguide region where electrons are injected. Parameters of the layers that allow implementation of the asymmetric-barrier design using pseudomorphic structures grown on GaAs substrates are determined. The calculation of the threshold characteristics of these laser structures demonstrates that suppression of electron-hole recombination outside the active region attained due to the use of asymmetric barrier layers leads to a significant decrease in the threshold current and an increase in the characteristic temperature of this type of lasers.     

Synthesis of graphene nanoribbons encapsulated in single-walled carbon nanotubes

A novel material, graphene nanoribbons encapsulated in single-walled carbon nanotubes (GNR@SWNT), was synthesized using confined polymerization and fusion of polycyclic aromatic hydrocarbon (PAH) molecules. Formation of the GNR is possible due to confinement effects provided by the one-dimensional space inside nanotubes, which helps to align coronene or perylene molecules edge to edge to achieve dimerization and oligomerization of the molecules into long nanoribbons. Almost 100% filling of SWNT with GNR is achieved while nanoribbon length is limited only by the length of the encapsulating nanotube. The PAH fusion reaction provides a very simple and easily scalable method to synthesize GNR@SWNT in macroscopic amounts. First-principle simulations indicate that encapsulation of the GNRs is energetically favorable and that the electronic structure of the encapsulated GNRs is the same as for the free-standing ones, pointing to possible applications of the GNR@SWNT structures in photonics and nanoelectronics.     

Novel indium(III) complexes with sterically hindered o-iminobenzoquinone

The first examples of indium(III) derivatives based on sterically hindered 4,6-di-tert-butyl-N-(2,6-di-iso-propylphenyl)-o-iminobenzoquinone (imQ) were synthesized and characterized in details. The interaction of sodium o-iminobenzosemiquinolate with indium(III) iodide produces bis[4,6-di-tert-butyl-N-(2,6-di-iso-propylphenyl)-o-iminobenzosemiquinonato]-iodo-indium(III) (1). The same product 1 was obtained by the reactions of imQ with InI or imQ disodium derivative with indium(III) iodide. The interaction of imQ with InI₃ results in the formation of indium(III) compound (2) containing neutral form of o-iminobenzoquinone ligand. Structures of complexes 1 and 2 were determined by X-ray diffraction analysis.     

Increasing the wear resistance of linings of ore furnaces for melting normal electrocorundum

The use of air-cooled linings on ore furnaces for melting normal electrocorundum has made it possible to increase their wear resistance by an order of magnitude. This is explained by the formation of a steady solid-phase skull due to a higher temperature gradient with a total decrease in the thermodynamic levels of the ambient and the refractory lining.Translated from Ogneupory, No. 10, pp. 29 – 30, October, 1995.     

Dynamic Compression of High-Strength Steel and Titanium Alloy

We describe a procedure of impact compression of 20Kh2N4A high-strength steel and VT-8 titanium alloy and present some experimental results accumulated for these materials. The analysis of these data demonstrates that compression strength significantly increases as the investigated range of strain rates becomes larger by an order of magnitude. Moreover, the compression strength of the studied materials strongly increases with the strain rate.     

Creep of the eye sclera

 Irreversible stretching (creep) of the eye sclera, considered as a cause of the high myopia, has been studied experimentally. Both dramatic acceleration and significant deceleration of the sclera creep have been observed in the presence of some enzymes. Creep of various connective tissues caused by static and cyclic mechanical stresses (gravity, blood pressure, etc.) can manifest in many age and pathological changes in human body. Authors express the hope that investigations in this area and finding appropriate inhibitors may replace surgery (eye, cosmetic) by prophylactic therapy. Received: 21 July 1998 / Accepted: 28 August 1998