Nowadays, numerous researches are being performed to formulate nontoxic multifunctional magnetic materials possessing both high colloidal stability and magnetization, but there is a demand in the prediction of chemical and colloidal stability in water solutions. Herein, a series of silica-coated magnetite nanoparticles (MNPs) has been synthesized via the sol-gel method with and without establishing an inert atmosphere, and then it was tested in terms of humic acids (HA) loading applied as a multifunctional coating agent. The influence of ambient conditions on the microstructure, colloidal stability and HA loading of different silica-coated MNPs has been established. The XRD patterns show that the content of stoichiometric Fe3O4 decreases from 78.8% to 42.4% at inert and ambient atmosphere synthesis, respectively. The most striking observation was the shift of the MNPs isoelectric point from pH~ 7 to 3, with an increasing HA reaching up to the reversal of the zeta potential sign as it was covered completely by HA molecules. The zeta potential data of MNPs can be used to predict the loading capacity for HA polyanions. The data help to understand the way for materials’ development with the complexation ability of humic acids and with the insolubility of silica gel to pave the way to develop a novel, efficient and magnetically separable adsorbent for contaminant removal.

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The article presents the results of a study of electromagnetic effects from space rocket activity using the example of the Plesetsk cosmodrome and aviation complex using the example of Ostafyevo Airport. The influence of electromagnetic pollution on the environment is considered; the authors analyze the influence of electromagnetic fields on human health taking into account thermal effects. It was demonstrated that the long-term effect of electromagnetic sources with different wavelengths at moderate intensity causes changes in the irritability of visual, olfactory and vestibular analyzers, as well as development of functional disorders in the nervous system without pronounced changes in endocrine-metabolic processes and blood composition, also trophic disturbance might be present. The authors study in detail the main anthropogenic sources of electromagnetic effects from objects of rocket and space, and aviation activities.

A simplified physical and mathematical model of combined thermal conductivity and filtering of a cooler with a strong dependence of dynamic viscosity on temperature during film cooling of bodies was developed. The model takes into account the inflow of the cooler into the gas-dynamic boundary layer and the evaporation of the resulting protective film of the cooler. Analytical solutions are obtained for the mass evaporation rate, the rate of non-isothermal filtration, and the temperature distribution in the body, taking into account filtration. The resulting relationships are calculated by iterative methods. Analytical solution of the problem permitted us to clearly establish the functional relationship of all the defining characteristics of the system for automatic cooling of bodies.

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The purpose of the article is to analytically solve the conjugate problem of heat transfer in a viscous shock layer on a blunt object and thermal conductivity in an anisotropic half-space. A feature of the flow around such bodies near the critical point is that in this case, the boundary layer equations are not satisfied and it is necessary to solve the Navier-Stokes equations together with the equations of continuity, state, and energy, however, in a stationary formulation of an incompressible flow. The problem of coupled heat transfer between a viscous shock gasdynamic layer and anisotropic half-space with the assumption of incompressibility of the gasdynamic flow behind the normal part of the shock wave is posed. An analytical solution to this problem is obtained with a boundary condition at the gas-solid object interface in the form of a parameter – temperature, as well as an analytical solution to the thermal conductivity problem in an anisotropic half-space with the same boundary condition.

The scientific paper analyzes the influence of the catalytically active surface on the intensity of heat and mass transfer in a chemically active boundary layer. Some features of the mechanism of heat and mass transfer under conditions of heterogeneous catalysis are indicated. Heat transfer analysis is performed in the laminar “frozen” boundary layer with zero and absolute catalytic surface activity. In order to improve the accuracy of the calculation of heat fluxes on the catalytically active surface, a modification of the Gullard ratio is carried out. Using the modified Gullard ratio obtained in this work, calculations of heat transfer on a catalytically active surface are carried out. It is shown that the levels of heat fluxes calculated using a modified ratio of up to 30% below the levels of heat fluxes obtained from the Gullard ratio under otherwise equal conditions.

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