Electrochemical doping of graphene with toluene

The electrical properties of graphene are known to be modified by chemical species that interact with it. We investigate the effect of doping of graphene-based devices by toluene (C₆H₅CH₃). We show that this effect has a complicated character. Toluene is seen to act as a donor, transferring electrons to the graphene. However, the degree of doping is seen to depend on the magnitude and polarity of an electric field applied between the graphene and a nearby electrode. This can be understood in terms of an electrochemical reaction mediated by the graphene crystal.     

Regeneration dynamics of the carboxyl cation exchanger with sulfuric acid in the mode of loosening its layer

The paper presents the research results of the regeneration process of carboxylic cation exchanger Lewatit CNP 80, depleted in water softening, by sulfuric acid in the mode of loosening its layer. It has been established that the theoretical model of sorption intradiffusion dynamics adequately describes the regeneration process in this mode. The value of the effective kinetic coefficient of internal mass transfer does not vary in an increase of the expansion of the layer and coincides with this value in a dense layer.     

Texture formation on the friction surface in transformation-toughened ceramics

The surface of Y-TZP ceramics after dry friction on steel in a wide range of relative sliding velocities (0.2–11.1 m/s) was studied by X-ray diffraction. An analysis of the surface structure showed that the texture state of the friction surface is similar to that observed for analogous materials upon rough grinding. The main trends in the I ₍₀₀₂₎/I ₍₂₀₀₎ intensity ratio characterizing the tetragonal ZrO₂ phase as a function of the sliding velocity and the ceramic grain size are established. The mechanisms of lattice reorientation operative at various sliding velocities are discussed.     

Damping of the mechanical vibrations of a piezoelectric element by sensitive coatings

A method of calculating the viscoelastic properties of moisture-sensitive polymer films deposited on the piezoelectric element of a quartz resonator is proposed.Translated from Inzhenerno-fizicheskii Zhurnal, Vol. 60, No. 6, pp. 994–999, June, 1991.     

Classification of radar signatures by autoregressive model fittingand cluster analysis

Ninety radar signatures were digitally recorded during the probing of ten different land and marine objects with a pulsed coherent Doppler radar. Their spectra were evaluated on the basis of the Marple algorithm for autoregressive model fitting. An attempt at classification is made. The method consists in representing the radar signatures as points in four-dimensional space and identifying the obtained clusters of four-dimensional points with the observed objects. The cluster analysis is carried out assuming that the classification parameters have different clustering lengths     

Production and Heat Treatment of Yarn from Copolyamide Based on Poly-(p-Phenylene Terephthalamide)

Fibres made of an aromatic rigid-chain copolyamide based on PPTA were manufactured by spinning through an air gap from liquid-crystalline sulfuric-acid solutions. In heat treatment under tension, marked structural changes take place in Armalon copolymeric fibres which significantly increase their strength and modulus of elasticity.