Search

The results of studies on layer-by-layer synthesis of multilayers on the electrode surface in order to design electrochemical sensors for the determination of concentrations of inorganic, organic and bioorganic compounds are summarized and analyzed. The principle of the method is discoursed and the key advantages of the approach are highlighted, such as the possibility of single layer synthesis with specified thickness and composition under mild conditions with further fabrication of multilayers. Charge transfer conditions in the layers on the electrode surface between the analyte molecules and electrode redox centres and the operating conditions for the optimal electrode are considered. The role of electrocatalysts and intermediates of these processes is noted. Particular attention is devoted to the methods for synthesis of gold nanoparticles with different diameters. Analytical characteristics for electrochemical sensors are presented and application prospects of the layer-by-layer synthesis to electrode fabrication are discussed. The bibliography includes 241 references.

Because of the nonisothermality of the plasma stream, the most intense acceleration and heating of particles occur in its initial portion. In the main portion the acceleration and heating are less intense. The relationships derived make it possible to estimate the temperature and velocity of particles at any point within the spray-deposition range. The results yielded by a calculation of the temperature and velocity of tungsten particles in argon are in accord with experimental data.

Conclusions 1.The magnitude of the residual stresses and their sign and distribution across the section of carburized plus quenched specimens depend on the case depth and steel composition.2.As the case depth increases from 0. 6 to 2. Z mm (0. 024 to 0. 087 in), the surface residual stresses change systematically. With a relatively shallow case, there are surface compressive stresses which increase until the case depth has reached 1.2 mm (0.047 in). With still heavier cases, they start to decrease and when the depth reaches 2 mm, they change to tensile stresses.3.Corresponding to the change in surface residual stresses, there is a change in the magnitude and character of the stresses through the section of case carburized specimens. When the case depth does not exceed 1.2 mm, the residual stresses within the section change smoothly. When the depth is above 2 mm there is a sharp drop of the compressive stresses.4.The magnitude and sign of the residual stresses is greatly affected by the presence of excess carbides and retained austenite in the case.

1.A study of the mechanical properties of steel 30KhGS showed that repeated impact loads bring out peculiarities which cannot be observed in static tests and in tests involving single bending impacts.2.The curve for impact fatigue strength of this steel as function of the tempering temperature shows two maxima: one at 200°C and the other at 400°C. The magnitude of these maxima is determined by the single-blow energy.