An approach to estimating the dry deposition velocity of aerosol particles on the surfaces of Arctic regions, where snow-covered surfaces, open-water surfaces, tundra, and coniferous forest predominate, is proposed and numerically investigated. Optimal modeling conditions are proposed, taking into account the characteristic sizes and densities of aerosol particles involved in transport in the planetary boundary layer and the interaction of air flows with the surface through the parameter u*, calculated using the WRF-ARW model. The proposed approach is compared with other known models and experimental data. The dependence of the dry deposition velocity obtained by this approach on the diameter, density of aerosol particles, and dynamic velocity u* for the surfaces in the Far North is estimated.

Respiratory protective equipment (RPE) is in high demand during epidemics and pandemics. The SARS-CoV-2 pandemic has demonstrated that the global industry had insufficient capacity for providing people with high-efficiency respirators. In this context, it is important to assess the protective properties of equipment designed to prevent the spread of infections. In this review, the hydrodynamic and filtering characteristics of modern RPE types present in the market, as well as their consumer performance, are analyzed taking into account the properties of virus-bearing aerosols. Approaches to developing novel, more efficient fiber-based RPE are proposed.

During the period from May, 1986 to November, 1987 the aerosol samples were collected around the Chernobyl nuclear power plant to define radioactive aerosol particle sizes by filter pack technique. The parameters of lognormal distribution (activity median aerodynamic diameter, AMAD, and geometric standard deviation) were defined for various radionuclides in aerosol form. The submicron aerosol particle were only shown to be produced by the damaged block-4 during the initial period after the accident. AMAD was increased up to 4–6 μm at the following stages when the secondary updraft of aerosol particles from contaminated surfaces became the dominant source of radioactive aerosols.

A microphysical model has been proposed to assess the scavenging of artificial aerosol particles from the atmosphere by raindrops, where the raindrops are regarded as a highly rarefied filtering medium. The effect of aerodynamic parameters of aerosol particles on the efficiency of their capture by raindrops E and on the scavenging coefficient Λ has been numerically investigated for different precipitation rates I. A new formula has been proposed to evaluate the efficiency of aerosol capture by the raindrops. This model has been compared with other well-known models. The proposed model has been found to describe the interaction between aerosol particles and raindrops more strictly than the microphysical models considered in this study.

The results of an investigation of the effect of collimators with a square cell on the detection efficiency of α-particles and the energy resolution of the spectra of α-emitting aerosols, which were first collected on a filter made of ultrafine polymers fibers, are reported. The investigations will make it possible to develop in the future new and improved already existing apparatus for express spectrometry of α-emitting aerosols.

The results of modeling performed with the MELCOR code of the transport and precipitation of fission product aerosols in the steam-water lines of RBMK during beyond design basis accidents are presented. It is shown that the precipitation of fission product aerosols on the inner surfaces of steam-water lines depends on the course of the accident and can be an effective mechanism for lowering their atmospheric emissions.

Data on the radionuclide composition, volume activity, and dispersity of aerosols taken in 2010–2014 using Petryanov’s filters in rooms 012/7, 012/15, and 210/7 of the Shelter object, into which the lava-like fuel-containing materials (LFCMs) flew after the accident, are presented. In room 012/7, the volume activities of aerosols carrying the Chernobyl accident products are higher by an order of magnitude than those in rooms 012/15 and 210/7. In all the rooms, the carriers of the radioactive products of the accident are, as a rule, aerosols with the activity median aerodynamic diameter larger than 1 µm. This value suggests the dispersion origin of the aerosols. In room 012/7, the aerosols are larger than in the other two rooms. The identity of the radionuclide composition of aerosols and LFCMs in room 012/7 shows that aerosols arise from the degradation of the lava. Considerable difference in the radionuclide compositions of aerosols and LFCMs in rooms 012/15 and 210/7 shows that the lava degradation in these rooms is less intense and that the aerosol generation from the lava surface does not influence the radionuclide composition of aerosols.

This paper is devoted to study of the process of electrospinning fiber materials based on biodegradable and biocompatible polylactides in L and D,L isomer forms. We assess the effect of the rheological properties of the polymer solutions on the course of the process and we establish the optimal synthesis parameters and conditions for obtaining microfiber materials. We examine the effect of the properties of the polymer solution and technological characteristics of the spinning process on the structure and functional properties of material made from polylactide. Therapeutic drugs are incorporated into the fiber structure.

The penetration of submicron particles through fine-fibrous filtering materials is studied. The existing theoretical approach to the description of the fine filtration of aerosols on the basis of the fan model filter is compared with experiments performed on a TSI 31–60 unit. Monodisperse aerosols of sodium chloride and dioctylphthalate are passed through several layers of filtering materials consisting of ultrafine polydisperse fibers. From measurements, it follows that the logarithm of the penetration coefficient of particles with radius r = 0.05–0.20 μm is directly proportional to the number of layers. The most penetrating particle radii r* found from experiments within this range of r and the collection coefficients corresponding to them are in good agreement with the calculations performed for the model on fan filter in the mode of diffusion deposition of finite-size particles with consideration for the slip of a gas over fibers, the action of retarded van der Waals forces, and also the polydispersity of fibers and the structural heterogeneity of filters. The penetrations measured for particles with r < 0.04 μm do not correspond to the exponential law of filtration. The penetration is increased in each subsequent layer of material.

The article considers stretching of liquid polyacrylonitrile jet in electrostatic field. Polymers with molecular weight from 130 000 to 700 000 were investigated. Regularities of stretching of the jet based on polyacrylonitrile solutions were determined.

The deposition of aerosol particles onto filter fibers under the effect of inertial forces is studied in a wide range of Stokes numbers (St) at Reynolds numbers close to unity (Re ∼ 1). Coefficients η of the capture of inertial particles with finite sizes in model filters composed of parallel rows of identical parallel fibers located normal to the direction of a flow are determined based on the numerical solution of the Navier-Stokes and particle motion equations. It is shown that, at Re < 1 and a constant particle-to-fiber radius ratio, R = r p / a , number St uniquely characterizes capture coefficients η for particles with different densities, while, at Re ≥ 1, the capture coefficient depends on both St and Re. At constant R and St values, the larger Re the higher the capture coefficient. The influence of the structure of the model filter on pressure drop Δ p and η is investigated. A nonuniform arrangement of fibers in rows is shown to increase the Δ p / U ratio at lower Re values and to make the η -St dependence more pronounced than that for systems of uniformly ordered fibers. The results of calculations agree with the experimental data.

In the article influence of the molecular weight of polyacrylonitrile on electrospinning process and also on the diameter and mechanical properties of the obtained fibers and fiber materials are considered. Polymers with molecular weight from 280 000 to 700 000 were investigated. Fibers with a diameter from 200 to 1100 nm were obtained.

In 2003–2007, the content of 212Pb (220Rn daughter product) inside the Shelter was, as a rule, in the range 0.5–5 Bq m−3. No seasonal and time dynamics of the 212Pb concentration and no relationship with the technical activity were revealed. At simultaneous sampling of aerosols, the volume activities of 212Pb in the bypass were higher by 1–2 orders of magnitude than in the surrounding medium (local zone). Hence, the sources of 220Rn emanation, in particular, 232U are inside the Shelter. Among 220 samples taken in the bypass, 94% had the activity median aerodynamic diameter of aerosol particles bearing 222Rn and 220Rn daughter products in the range from 0.05 to 0.4 μm. For the Shelter staff members, 222Rn and 220Rn daughter products, and also submicron size of their carriers are negative factors which were not taken into account previously when determining ionizing irradiation doses. The additional inhalation doses can reach tens of percents of the permissible annual dose.