Control of light polarization by voltage in excitonic metasurface devices

We propose active metasurface devices where the state of emitted light is controlled by voltage. Based on the simulations of expected emission spectra, we present the concept of a light emitting device with voltage controlled wavelength and degree of linear polarization of emission. The device combines the ability of metasurfaces to control light with a wavelength-tunable light source based on indirect excitons in coupled quantum well heterostructures

Surface modification of platinum with copper and by plasma-chemical treatment and the effect on H-Pt bond energy

Kinetics of H2 desorption from the surface of a platinum catalyst applied to silica gel, as well as from the surface of the same catalyst modified with a copper additive, is studied. Desorption of hydrogen was studied both before and after the treatment of the catalyst in the electric glow discharge of argon or oxygen or in the high-frequency H2 plasma. The H-Pt bond energy was found to increase upon the introduction of cop- per additive and decrease upon the plasma-chemical treatment of copper-platinum specimens. In the latter case, the size of metal particles increases and the microstrain in them decreases. The observed changes in H- Pt bond energy are explained by the change in the electronic state of the surface and the increase in the num- ber of metal structure defects. © Pleiades Publishing, Ltd., 2012

Investigation of residual stresses in welded joints of heat-resistant magnesium alloy ML10 after electrodynamic treatment

In repair of aircraft structures of magnesium alloy ML10, the argon arc non-consumable electrode welding is used. In this case, the residual welding stresses occur in repair welds, being one of the causes for reducing the service characteristics of the restored products. Residual stresses arise as a result of welding. Post-weld heat treatment is used to reduce the residual stresses. The heat treatment, which occurs after welding, increases the cost of repair. This leads to the search for alternative methods to control the stressed state of welded joints, one of which is electrodynamic treatment, which reduces the level of residual stresses in repair welds, and as a consequence, the cost of the welding repair in restoring aircraft structures. It was found from the results of experiments carried out, that the electrodynamic treatment allows reduces the initial level of stresses in welded joints, reaching 120 MPa, to 30 MPa, and at definite geometric characteristics of the specimens forming the field of compressive stresses, the values of which are equal to –50 MPa. It is shown that the optimum distance between the zones of treatment, being 5 mm, provides the guaranteed covering the zones of electrodynamic effect and, as a consequence, the maximum efficiency of the electric dynamic treatment

Surface modification of platinum with copper and by plasma-chemical treatment and the effect on H-Pt bond energy

Kinetics of H2 desorption from the surface of a platinum catalyst applied to silica gel, as well as from the surface of the same catalyst modified with a copper additive, is studied. Desorption of hydrogen was studied both before and after the treatment of the catalyst in the electric glow discharge of argon or oxygen or in the high-frequency H2 plasma. The H-Pt bond energy was found to increase upon the introduction of cop- per additive and decrease upon the plasma-chemical treatment of copper-platinum specimens. In the latter case, the size of metal particles increases and the microstrain in them decreases. The observed changes in H- Pt bond energy are explained by the change in the electronic state of the surface and the increase in the num- ber of metal structure defects. © Pleiades Publishing, Ltd., 2012

Repair of ship hull structures of aluminium alloy AMg6 using electrodynamic treatment

The electrodynamic treatment (EDT) of welded joints from aluminium alloys AMg6 in ship hulls was carried out. The effect of 50...60 % reduction of initial stressed state was obtained at EDT of full-size samples of welded joints. Technological recommendations for EDT of ship welded hulls were worked out. A high process efficiency was shown by monitoring welded joints of hulls after EDT.Peer reviewe

Effects of plasmochemical treatments and cerium additions on the structural characteristics and activity of copper catalyst particles in isopropanol dehydrogenation

The effect of the treatment of the 5 wt % Cu/SiO 2 (I) and (5 wt % Cu + 0.5 wt % Ce)/SiO 2 (II) catalysts with glow discharge plasma in O 2, H 2, and Ar on their structural characteristics was studied by X-ray phase analysis; the influence of cerium additions and plasmochemical treatments on the catalyst activity in isopropanol dehydrogenation was also investigated. Under the plasmochemical treatment, the diameters of Cu particles in catalyst I nearly doubled and microstresses in the metal particles also changed. Catalyst II was X-ray amorphous both before and after plasmochemical treatments. The activity of I after plasmochemical treatment increased because of the increase in the number of centers and changes in their composition. Growth of the activity of I compared with the activity of II was explained by the formation of new catalytic centers due to positive charging of the C +α e adatom on the surface of the copper particle. © Pleiades Publishing, Ltd., 2012

Effects of plasmochemical treatments and cerium additions on the structural characteristics and activity of copper catalyst particles in isopropanol dehydrogenation

The effect of the treatment of the 5 wt % Cu/SiO 2 (I) and (5 wt % Cu + 0.5 wt % Ce)/SiO 2 (II) catalysts with glow discharge plasma in O 2, H 2, and Ar on their structural characteristics was studied by X-ray phase analysis; the influence of cerium additions and plasmochemical treatments on the catalyst activity in isopropanol dehydrogenation was also investigated. Under the plasmochemical treatment, the diameters of Cu particles in catalyst I nearly doubled and microstresses in the metal particles also changed. Catalyst II was X-ray amorphous both before and after plasmochemical treatments. The activity of I after plasmochemical treatment increased because of the increase in the number of centers and changes in their composition. Growth of the activity of I compared with the activity of II was explained by the formation of new catalytic centers due to positive charging of the C +α e adatom on the surface of the copper particle. © Pleiades Publishing, Ltd., 2012

Effect of plasmochemical treatment of platinum catalyst on dispersity of metal phase and its catalytic activity

We studied how treatment of 0.64 wt % Pt/SiO2 catalyst with a glow-discharge plasma in O2 and a high-frequency plasma in H 2 (HF H2) influences the cyclohexane dehydrogenation reaction. The effect of plasmochemical treatment on the average diameter of platinum particles was established by the method of X-ray diffraction analysis. It was found that oxygen plasma increases the surface area of the metal by ∼15% and diminishes activity by raising the activation energy and reducing the number of active centers per unit surface of the metal. The HF H2 plasma increases the reaction rate constant many times over, due to the number of active centers per unit surface of the metal rising sharply while the size of the Pt particles remains unchanged. © Pleiades Publishing, Ltd., 2010

Dependence of the adsorption and catalytic properties of a copper-platinum catalyst on the structure of metal particles and the composition of the catalyst surface

The kinetics of H2 desorption from the surface of a copper-platinum catalyst deposited on silica gel ([1 wt % Pt + 0.15 wt % Cu]/SiO2) and the kinetics of C6H12 dehydrogenation were studied. The effects of copper introduction in a platinum catalyst on the structural characteristics of platinum particles, the com- position of their surface, and the effects of plasmochemical treatments on these parameters were studied by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The metal-H atom bond energies (EPt-H) and the catalytic activity were found to increase in the presence of Cu. This was explained by the for- mation of new hydrogen adsorption centers (due to the Cu+δ adatoms) and catalytic centers composed of Cu +δ adatoms and carbon atoms. The mean diameter of Pt particles (D) increased twofold. The microstresses (ε) in the particles increased after the catalyst was treated with glow discharge plasma in Ar and O 2 and with high-frequency plasma in H2 (HF-H2). The observed changes in the bond energy EPt-H and kinetic param- eters were explained by the increase in microstresses in Pt particles. © 2011 Pleiades Publishing, Ltd