Angular distributions of Ni and Ti atoms sputtered from a NiTi alloy under He and Ar ion bombardment

The angular distributions of sputtered components were measured for NiTi polycrystalline alloy under 9 keV Ar⁺ and He⁺ ions bombardments with various fluences in ultrahigh vacuum. Combination of Rutherford Backscattering Spectrometry (RBS) and Auger Electron Spectrometry (AES) techniques allowed us to observe enhanced concentration of Ni over a layer with thickness comparable to a primary He⁺ ions penetration depth due to selective sputtering of Ti atoms and radiation-induced diffusion processes. A preferential emission of Ni atoms towards the surface normal was observed during bombardment by both He⁺ and Ar⁺ ions. More forward-peaked “over-cosine” angular distributions of sputtered Ni in comparison with those for Ti atoms have been measured. Nonstoichiometric sputtering of NiTi alloy dependent on emission angle was observed for bombardment fluence of He⁺ well below that needed for the steady-state altered layer formation. To explain the peculiarities of NiTi sputtering, an interpretation is discussed in terms of sputtering due to backscattered He⁺ ions.     

A method for numerical solution of a multidimensional convection-diffusion problem

We propose a modification of the additive splitting algorithm to solve the convection-diffusion problem using an efficient finite-difference scheme. The modification decreases the number of data exchanges and their amount during the numerical solution of a system of multidimensional equations. Approximation, stability, and convergence are considered. Translated from Kibernetika i Sistemnyi Analiz, No. 1, pp. 100–107, January–February 2009.     

Choosing the parameter of a modified additive-averaged splitting algorithm

The problem-solving time and the solution accuracy are expressed as functions of a parameter. An optimization problem of choosing the parameter using a “time cost–solution accuracy” criterion is considered. A Pareto-optimal set of solutions is obtained. The best value of the parameter is chosen by the ideal-point method. Translated from Kibernetika i Sistemnyi Analiz, No. 4, pp. 98–105, July–August 2009.     

Defect formation and recrystallization mechanisms in silicon-on-sapphire films under ion irradiation

The effect of the parameters (energy, dose) of the irradiation of silicon-on-sapphire (SOS) structures with ions Si⁺ ions on the quality of the silicon-film crystal structure after solid-phase epitaxial recrystallization and annealing is studied. It is shown that the most efficient mechanism of crystal-structure recovery is recrystallization from the silicon surface layer which is a seed.     

Increasing the effectiveness of thiamine by its administration together with methionine and vitamin E]

The influence of methionine and vitamin E, compounds intensifying thiol metabolism, on thiamine-phosphate level and thiamine-dependent dehydrogenase activity was studied in the liver of rats with varying thiamine providing: in case of its alimentary deficiency, and intensified thiamine consumption due to rat feeding with high-carbohydrate food. Methionine administration to vitamin B1-deficient rats led to a significant rise in thiamine-phosphate content and normalized alpha-ketoacid dehydrogenase acidity and non-protein SH-group level. Combined administration of thiamine with methionine and vitamin E increased the level of parameters studied. Methionine and vitamin E administered with thiamine intensified the regulatory action of thiamine on pyruvate dehydrogenase activity in the animals fed high-carbohydrate ration.