Studying the electrophysical parameters of a holographic microscope

In this work, the main parameters of a holographic microscope are studied with the aim of optimizing them. The optimum positions for the monochromatic electron-beam source with respect to the subject of research and for the screen detecting the interference pattern (the distance is 100 nm and 10 cm, respectively) are determined. The limiting thickness of the thin film of the subject of study (30 Å) at which the interference pattern can be observed is estimated. The main parameters of the coordinate-sensitive detector providing signal gain up to 105 at the output are calculated.     

The growth of controlled profile crystals by Stepanov's method

Single crystals in the shapes of plates, tubes and rods of various cross sections are widely used in many areas of science and technology. Of great importance is the production of such single crystal specimens directly from the melt. By Stepanov's method, the desired shape of the crystal is obtained by the proper selection of a device which shapes the melt column which rises due to the capillary effect. The capillary parameters determine the shape of the profile curve. The thermal parameters, taking into account the equilibrium crystal shape, define the position and shape of the crystallization front. The use of the shaper makes the process self-stabilizing. A negative feedback which damps out perturbations appears in the crystal-melt system and thus permits the production of controlled profile crystals with constant cross-section along their length. Thermoelastic stresses created in ribbons and rods as a result of temperature-induced misfit deformations are considered. The generation of dislocations in crystals occurs mainly due to stresses arising near the crystallization front. Various versions of the method and their applications to some materials are discussed.     

Specific features of the interaction of α- and γ-modifications of Al<Subscript>2</Subscript>O<Subscript>3</Subscript> with carbonate and carbonate-chloride melts

Data on reactivities of α- and γ-Al₂O₃ finely dispersed powders in a melted carbonate eutectic (Li₂CO₃–Na₂CO₃–K₂CO₃)_eut and carbonate-chloride mixture 0.72(Li₂CO₃–Na₂CO₃–K₂CO₃)_eut–0.28NaCl were obtained. The methods of synchronous thermal and X-ray phase analyses and Raman spectroscopy confirmed that, in contrast to γ-Al₂O₃, α-Al₂O₃ does not chemically interact with the melted carbonate eutectic and carbonate-chloride mixture (Li₂CO₃–Na₂CO₃–K₂CO₃)_eut–NaCl can be recommended as a thickening agent for a carbonate fuel cell.     

Acousto-Optic Deflector with Heat Removal from the Piezotransducer by Sound Insulation of a Heat Radiator

Acoustical Physics - A method is proposed for removing heat from the transducer of an acousto-optic deflector without substantial acoustic damping. The rear surface of the transducer and the...     

Effect of the Heating Scheme of Heterogeneous Droplets on the Characteristics of Micro-Explosion Fragmentation

Doklady Physics - According to experimental results, a comparison of sizes of child droplets after micro-explosion fragmentation of water–Diesel droplets is conducted. Convective, conductive,...     

Application of the Donkin Formula in the Theory of Reflecting and Turning Devices

Technical Physics - Electrostatic turning devices are electron- and ion-optical elements changing the direction of movement of a parallel monochromatic beam of charged particles by a given angle...     

Effect of torsional stresses on the magnetoimpedance of amorphous wires with negative magnetostriction

A model to describe the effect of torsional stresses on the magnetoimpedance of amorphous wires with negative magnetostriction is suggested. An approximate expression for the impedance with regard to the spatial distribution of magnetoelastic anisotropy induced by torsional stresses is derived. It is shown that the relative variation of the impedance is maximal near a critical stress value at which the surface magnetic structure of the wire changes. The calculated dependences of the impedance on the external magnetic field and torsional stress are in good qualitative agreement with experimental data for amorphous wires with negative magnetostriction.     

Efficient electron sources utilizing the effect of field emission

W-Cs₃Sb, W-TiO₂, and W-TiO₂-Cs field emission cathodes are fabricated and studied. All these cathodes outperform the conventional tungsten cathode in emission properties: the emission current is very stable and one-and-a-half to two orders of magnitude higher. Physical models of the new emitters are suggested and experimentally verified.     

Steered molecular dynamics simulations of cobra cytotoxin interaction with zwitterionic lipid bilayer: no penetration of loop tips into membranes

Cobra cytotoxins, small proteins of three-fingered toxin family, unspecifically damage membranes in different cells and artificial vesicles. However, the molecular mechanism of this damage is not yet completely understood. We used steered molecular dynamics simulations to study the interaction of cardiotoxin A3 from Naja atra cobra venom with hydrated 1-palmitoyl-2-oleoyl-1-sn-3-phosphatidylcholine (POPC) bilayer. The studied system included one cytotoxin molecule, 64 lipid molecules (32 molecules in each monolayer) and 2500 water molecules. It was found that the toxin interacted with zwitterionic bilayer formed by POPC. During first nanosecond of simulation the toxin molecule was oriented toward membrane surface by loops' basement including cytotoxin regions Cys14-Asn19 and Cys38-Ser46. This orientation was stable enough and was not changed during next 6 ns of simulation. The obtained data suggest that cytotoxin molecule cannot penetrate into membrane composed of zwitterionic lipids without some auxiliary interaction.