Amplification of plasma waves in shielded active graphene

Amplification of plasma waves in shielded graphene with inverted energy distribution of charge carriers is investigated theoretically. It is shown that graphene shielding allows one to increase an amplification factor of terahertz plasmons in several times compared to the case of amplification of unshielded plasmons due to strong field confinement of the shielded plasmons near graphene.     

One-zone rolling of composite materials

The energy–force parameters of free rolling of a strip without its tension and rolling with one backward or forward creep zone in the deformation zone are compared. The limiting backward or forward tensions are determined, and the change in the linear sizes of a composite billet during deformation in a rolling mill is considered.     

Effect of heat treatment on corrosion of laser-textured aluminum alloy surfaces

The kinetics of electrochemical corrosion of aluminum alloy (AlMg6) surfaces with different wettability was analyzed. The surfaces were processed by three different methods, in particular, polishing, laser texturing, the combination of laser texturing and low-temperature heating. After laser processing, the dimple-like texture was formed on the surface, and the wettability significantly enhanced. Low-temperature heating of laser-textured AlMg6 alloy surfaces led to the wettability inversion from strongly hydrophilicity to superhydrophobicity. Microscopic and profilometric methods were used to estimate the surface degradation due to corrosion when aggressive solution droplets (a mixture of NaCl and hydrogen peroxide aqueous solutions) evaporated. The potentiodynamic polarization measurements of AlMg6 alloy surfaces were conducted. The typical modes of corrosion and evaporation of aggressive solution droplets were detected. The kinetics of corrosion was estimated by the behavior of the corrosion area evolution. In addition, when immersing laser-textured sample with strongly hydrophilic properties into aggressive solution, the higher corrosion rate was found in the liquid meniscus region (aggressive mixture / alloy / air interface) compared to the textured site immersed in the mixture. This was explained by convection increasing the rate of reaction products removal and promoting a stronger deviation from the equilibrium state in the aggressive mixture. Experimental results of the potentiodynamic polarization measurements revealed that laser-textured samples exhibit enhanced corrosion protective properties compared to polished samples.

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Investigation of Stimulated Emission from HgTe/CdHgTe Quantum-Well Heterostructures in the 3–5 μm Atmospheric Transparency Window

Semiconductors - Stimulated emission based on interband transitions depending on the pumping wavelength is studied for heterostructures with Hg(Cd)Te/CdHgTe quantum wells in the wavelength region...     

The Mechanism and Parameters of Froth Flotation Stimulation for Diamond-Bearing Materials by Thermal and Electrochemical Effects

Journal of Mining Science - The thermodynamic analysis and tests of minerogenesis under higher temperatures determine conditions of thermochemical decomposition of hydrophilic attachments on...     

Chemical reactions in spherically symmetric problems of mechanochemistry

A stress-assisted chemical reaction front propagation in a linear elastic solid is considered. The reaction between gas and solid constituents is sustained by the diffusion of the gas through the transformed material. The consideration is based on the kinetic equation in a form of the dependence of the reaction front velocity on the normal component of the chemical affinity tensor that in turn depends on stresses and gas concentration. Spherically symmetric problems of mechanochemistry are solved for the reaction front propagation in a sphere, in a body with a spherical hole and in an inclusion placed into an infinite medium. It is demonstrated how stresses can enhance, retard and even lock the reaction. The effects of the sign and value of the reaction front curvature are also examined.     

An 8-bit parallel DAC with segmented architecture

An 8-bit parallel DAC with a segmented architecture that employs a 4-bit binary and an unary segments is presented. A switched current source and a thermometric decoder are discussed. A test chip is fabricated using a 180-nm CMOS technology. Measured results show higher conversion rate and smaller chip area in comparison with other papers.     

Deformation and heat treatment of NiAl-Y2O3-based powder alloys: I. Deformation and production of various pressed sections

The effect of a hot extrusion regime for workpieces produced by calcium hydride reduction (CHR) of mechanically activated powders of an NiAl intermetallic alloy and an NiAl-Y₂O₃ alloy composite on their deformability is studied to form various (round, flat, lens-shaped) sections. The extrusion regimes that make it possible to produce defect-free samples of the NiAl-Y₂O₃ alloy composite with a metal-deformed structure without traces of dynamic recrystallization are developed. Deformed semifinished samples are formed.