The functional role of nano-dispersed multi-layered composite coatings (NMCC) deposited on the working surfaces of cutting inserts (CI) made of the layered high-strength ceramic (LHC) to equip the cutting tools when cutting hardened (high-strength) steels was investigated. It is shown that the variation in the composition, structure and properties of coatings allows controlling the contact processes at cutting, increasing the length of contact, reducing normal contact stresses and probability of micro- and macro-brittle failure of tool cutting edge. The mathematical models of cutting which establish dependences of flank wear land of the tool, the tangential component of cutting force, power of cutting and roughness of the machined surface from conditions of cutting of high-strengthen steels are developed. It is found out that the application of nano-dispersed ceramic multi-layered coatings on ceramic tool significantly increases its wear resistance and improves the quality of machining.

Recent experiments on the UV and electron beam irradiation of solid O 2 reveals a series of IR features near the valence antisymmetric vibration band of O 3 which are frequently interpreted as the formation of unusual O n allotropes in the forms of weak complexes or covalently bound molecules. In order to elucidate the question of the nature of the irradiation products, the structure, relative energies, and vibrational frequencies of various forms of O n (n = 1−6) in the singlet, triplet, and, in some cases, quintet states were studied using the CCSD(T) method up to the CCSD(T,full)/cc-pCVTZ and CCSD(T,FC)/aug-cc-pVTZ levels. The results of calculations demonstrate the existence of stable highly symmetric structures O 4 (D 3h ), O 4 (D 2d ), and O 6 (D 3d ) as well as the intermolecular complexes O 2 ·O 2 , O 2 ·O 3 , and O 3 ·O 3 in different conformations. The calculations show that the local minimum corresponding to the O 3 ···O complex is quite shallow and cannot explain the ν 3 band features close to 1040 cm −1 , as was proposed previously. For the ozone dimer, a new conformer was found which is more stable than the structure known to date. The effect of the ozone dimer on the registered IR spectra is discussed.

We examine the applicability of the assumption that nighttime ozone is in photochemical equilibrium. The analysis is based on calculations with a 3‐D chemical transport model. These data are used to determine the ratio of correct (calculated) O3 density to its equilibrium value for the conditions of the nighttime mesosphere depending on the altitude, latitude, and month in the annual cycle. The results obtained demonstrate that the retrieval of O and H distributions using the assumption of photochemical ozone equilibrium may lead to a significant error below 81–87 km depending on season. Possible modifications of the currently used approach that allow improving the quality of retrieval of O and H mesospheric distributions from satellite‐based observations are discussed.

Abstract. The mechanism of generation of 2-day photochemical oscillations in the mesopause region (80-90 km) has been studied analytically. The initial system of equations of chemical kinetics describing the temporal evolution of O, O 3 , H, OH and HO 2 concentrations with allowance for diurnal variations of solar radiation has been simplified successively to a system of two nonlinear first-order time equations with sinusoidal external forcing. The obtained system has a minimum number of terms needed for generation of 2-day oscillations. Linearization of this system near the perioddoubling threshold permits separating explicitly a particular case of the Mathieu equationẍ+α·sin ωt ·x = 0, in which the first sub-harmonic (ω/2) of the exciting force starts to grow exponentially when the amplitude of external forcing (α) exceeds its threshold value. Finally, a system of two simplest differential equations with power-law nonlinearity has been derived that allows analytical investigation of the effect of arising of reaction-diffusion waves in the mesospheric photochemical system.

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[1] The influence of a quasi-2-day atmospheric wave of given amplitude on the 2-day photochemical oscillations occurring in the mesopause region (heights of 80 to 90 km) in the regime of subharmonic nonlinear response to diurnal variations of solar radiation is investigated. It is revealed that the most significant mechanism is periodic transport of minor gas constituents by the vertical wind associated with the wave. This mechanism may lead to phase locking of photochemical oscillations to wind oscillations and, thereby, to the formation of regular horizontal distribution of minor gas constituents with zonal wave number close to the wave number of the atmospheric wave. The influence on phase locking of two other factors, namely, transport by the zonal mean zonal wind and by the horizontal component of wind of the wave, is also analyzed.

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Abstract. For the retrieval of atomic oxygen via ozone observations in the extended mesopause region under sunlight conditions, two assumptions are used: first, the photochemical equilibrium of ozone and, second, that the ozone losses are dominated by ozone's dissociation from solar UV radiation, silently ignoring the O 3 destruction by atomic hydrogen. We verify both by 3-D modeling. We found that ozone approaches photochemical equilibrium at 75-100 km for daytime conditions. Hence, the first assumption is valid. However, the reaction of ozone with atomic hydrogen was found to be an important loss process and should not be omitted in retrieving atomic oxygen.