Cathode etching rate in abnormal glow discharges

The cathode etching rate in an abnormal glow discharge was calculated taking into account sputtering both by ions and energetic neutrals originating in cathode dark space due to the charge exchange collisions. The advantage of the model proposed is the evaluation of energetic neutral scattering by the sputtering gas.     

Dimension reduction in fluid dynamics equations

A method for transforming the Euler and Navier-Stokes equations and a complete system of fluid dynamics equations in three dimensions to a closed system on any moving surface is proposed. As a result, for an arbitrary geometric configuration, the dimension of the equations is reduced by one, which makes them convenient for numerical simulation. The general principles of the method are described, and verifying examples are presented.     

Synthesis and testing of chromogenic phenoxazinone substrates for beta-alanyl aminopeptidase

Novel 7-N-(beta-alanyl)aminophenoxazin-3-one salts 27a-d have been synthesized and tested as chromogenic substrates for beta-alanyl aminopeptidase, which is present in Pseudomonas aeruginosa, the most common respiratory pathogen in patients with cystic fibrosis. The biological results show that 7-N-(beta-alanyl)amino-1-pentylphenoxazin-3-one trifluoroacetate salt 27a is a chromogenic substrate for this bacterium, with a low degree of diffusion in nutrient media for growing bacterial cultures and a bright red colour, making it easily distinguishable from the agar background.     

Parametric Study of the Noise from Vortex Rings with Various Diameters

A technique for studying the aeroacoustic parameters of vortex rings with various diameters in an anechoic chamber is developed. The motion trajectories of vortex rings produced by a piston generator with nozzles with various exit diameters are studied. Spectral analysis of the noise of vortex rings for various distances from nozzles with various diameters is carried out. For the first time, the dependences of the fundamental radiation frequency on the time of a ring’s motion are obtained in dimensionless form. The data on noise from turbulent vortex rings confirm the conclusion that sound from rings with different diameters and velocities is emitted by the same mechanism.     

The influence of local phonon modes in a wide-band matrix on the tunnel current-voltage characteristics of quasi-zero-dimensional structures

Experimental results on the visualization of the density of states in InAs/GaSa(001) quantum dots that were obtained by tunnel atomic-force microscopy in an ultrahigh vacuum are presented. A one-dimensional (1D) model of dissipative quantum tunneling is proposed for describing experimental current-voltage characteristics of a tunnel contact between an atomic force microscope probe and the surface of InAs/GaAs (001) quantum dots. It was found that the influence of two local modes of the wide-band matrix on the probability of 1D dissipative tunneling leads to the appearance of several randomly spaced peaks in the field dependence. It was shown that the theoretical dependence agrees qualitatively with experimental the current-voltage characteristic of the atomic force microscope tip and the surface of InAs/GaAs(001) quantum dots.     

Synthesis of epoxyoxirano- and epoxydihydroxyisoindolones

1-Oxo-3a,6-epoxyisoindolones oxidized with potassium permanganate to give 4,5-dihydroxy-3a,6-epoxyisoindolones, while oxidation with peroxyformic acid or 3-chloroperoxybenzoic acid yielded 2,6a-epoxyoxirano[e]isoindolones. Oxidation proceeded with selective formation of exo-cis-adducts.     

First example of the cascade acylation/IMDAV/ene reaction sequence,leading to N-arylbenzo[f]isoindole-4-carboxylic acids possessing anti-viral activity

The reaction between readily accessible N-aryl-3-phenylallylamines and maleic anhydride led to unexpected products – polysubstituted hydrogenated benzo[f]isoindole-4-carboxylic acids. This transformation proceeds through a previously unknown sequence of steps: N-acylation of the allylamine with maleic anhydride, intramolecular Diels-Alder reaction of the vinylarene in the intermediate N-maleamide, and Alder-ene reaction of the products of the previous two steps. Selected benzo[f]isoindoles displayed antiviral activity.     

The Galois closure of the Garcia–Stichtenoth tower

We describe the Galois closure of the Garcia–Stichtenoth tower and prove that it is optimal.     

Sapphire shaped crystals for waveguiding,sensing and exposure applications

Second half of the XX century was marked by a rapid development of sapphire shaped crystal growth technologies, driven by the demands for fast, low-cost, and technologically reliable methods of producing sapphire crystals of complex shape. Numerous techniques of shaped crystal growth from a melt have been proposed relying on the Stepanov concept of crystal shaping. In this review, we briefly describe the development of growth techniques, with a strong emphasize on those that yield sapphire crystals featuring high volumetric and surface quality. A favorable combination of physical properties of sapphire (superior hardness and tensile strength, impressive thermal conductivity and chemical inertness, high melting point and thermal shock resistance, transparency to electromagnetic waves in a wide spectral range) with advantages of shaped crystal growth techniques (primarily, an ability to produce sapphire crystals with a complex geometry of cross-section, along with high volumetric and surface quality) allows fabricating various instruments for waveguiding, sensing, and exposure technologies. We discuss recent developments of high-tech instruments, which are based on sapphire shaped crystals and vigorously employed in biomedical and material sciences, optics and photonics, nuclear physics and plasma sciences.