[en] States in the AlAs/GaAs(12)/AlAs(110) quantum well and AlAs(6)/GaAs(12)(110) superlattice are considered. For analysis of mixing of light- and heavy-hole states in these structures, a parameter-dependent set of basis functions is suggested and the values of the parameter at which one of the functions describes basically heavy-hole states and the other light-hole states are determined. For the energy region considered in the study, four energy levels are determined in the AlAs/GaAs(12)/AlAs(110) quantum well and, correspondingly, four minibands in the AlAs(6)/GaAs(12)(110) superlattice. Analysis shows that the first and fourth levels in the quantum well and the first and fourth minibands in the superlattice are related basically to heavy-hole states. The other two states in the quantum well and the second and third minibands in the super-lattice are structurally more complex: in these states and minibands, the hole states are noticeably mixed. In these minibands, states are substantially separated in space and in spin.

[en] The 18-band kp model is used to analyze the wave functions of the states in the valence band. It is found that the typically used approximation based on the assumption that the effective masses are energy-independent for the band of light and heavy holes is justified only near the valence-band top. The conditions for matching of the envelope functions for holes at the GaAs/AlAs heterointerfaces with the (111) and (110) orientations taking into account and disregarding the spin-orbit interaction for energies in the vicinity of the valence-band top are considered. These conditions are derived as a result of simplifying the description of electronic states using the pseudopotential method. The matching conditions obtained are completely consistent with the problem's symmetry. These conditions involve mixing of the envelope functions with their normal derivatives and mixing of derivatives with the functions. It is shown that the light and heavy holes are not mixed at the (111) heterointerface but are mixed at the (110) heterointerface. It is found that the states are mixed at resonance energies to a much greater extent at the (110) heterointerface than at the (001) interface

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[en] This paper presents the results of the works under the Russian RERTR Program for the past period and some plans for the future. In 1994, a branch program entitled 'Design of Fuel Elements and Fuel Assemblies with 20% Uranium-235 Enriched Fuel for Research Reactor Cores' was developed and initiated by the order of the Ministry of the Russian Federation for Atomic Energy. The major objectives of the Program are as follows: Prevention of nuclear weapons proliferation; retaining the market for FA supplies to the CIS and East European countries, etc.; enabling Russia's participation in competition projects for building research reactors in different countries of the world. In connection with the lack of financing, the 1994 Branch Program was not implemented in full within the schedule. Currently, Russian RERTR program has been developed and implemented, with the completion dates of 2004-2005. It has specified the works with regard for the revision of the concept of certain tasks and their accomplishment dates and also with introduction of new problem solution paths

[en] The Russian program started at the end of 70's. The final goal of the program was to minimize and in perspective to eliminate using of HEU in fuel elements and assemblies supplied to foreign research reactors with the minimum of penalties for the experimenters. Later officials, scientists and engineers began political and scientific discussion about reducing enrichment domestic reactors as well as return of fresh and spent HEU fuel. Important issues of the Russian program is concerned with cooperation with USA, especially related to new types of LEU fuel elements development and fabrication to be used in Russian designed foreign research reactors. According to present results this goal will be achieved by 2006

[en] A new tunnel resonance method to estimate the concentration of nano-sized objects in the product obtained by plasma-chemical synthesis compared to pure fullerene is proposed. We have complied tunnel resonant structure (TRS) which includes two barrier layers (silicon oxide and silicon monoxide) with nanosized particles layer between them, placed on the surface of silicon plate and covered by copper layer. The obtained TRS is connected to power supply circuit, current recorder and voltage register. Based on measured current-voltage characteristic the local current maxima and resonant potentials have been determined. The concentration of nano-sized objects in the synthesis products was estimated from the current amplitude for the corresponding resonant potentials. The article provides theoretical substantiation of the proposed methodology and considers its practical implementation. (paper)

No abstract available

[en] This paper presents results of the work under the Russian RERTR program for the past period and some plans for the future. (author)

[en] The article reviews efficient methods of accomplishing stronger bonds between concrete and outer steel shell through transverse prestressing of the concrete core. Load-strain diagrams are provided for concrete subject to uniaxial and triaxial compression. The authors describe formulas of the basic parametric point, a vertex, of a deformation curve of triaxially compressed concrete. When making estimations using these formulas, the following is considered: long-term stressing of concrete, specifics of its behavior under triaxial compression, and whether it was prestressed. (paper)