Propagation of viral bioaerosols indoors.

Here we look into the spread of aerosols indoors that may potentially carry viruses. Many viruses, including the novel SARS-CoV-2, are known to spread via airborne and air-dust pathways. From the literature data and our research on the propagation of fine aerosols, we simulate herein the carryover of viral aerosols in indoor air. We demonstrate that a lot of fine droplets released from an infected person's coughing, sneezing, or talking propagate very fast and for large distances indoors, as well as bend around obstacles, lift up and down over staircases, and so on. This study suggests equations to evaluate the concentration of those droplets, depending on time and distance from the source of infection. Estimates are given for the safe distance to the source of infection, and available methods for neutralizing viral aerosols indoors are considered

Aerosol cloud propagation in a closed space

This paper presents the results of an experimental–theoretical investigation of the evolution of a cloud of aerosol particles in a closed space obtained by the shock-wave method. It has been shown that the prevailing propagation mechanism of aerosol particles of diameter 1–7.5 μm is convective diffusion. For the considered class of aerosols, the effective value of the convective diffusion coeffi cient in a closed space has been determined

Aerosol cloud propagation in a closed space

This paper presents the results of an experimental–theoretical investigation of the evolution of a cloud of aerosol particles in a closed space obtained by the shock-wave method. It has been shown that the prevailing propagation mechanism of aerosol particles of diameter 1–7.5 μm is convective diffusion. For the considered class of aerosols, the effective value of the convective diffusion coeffi cient in a closed space has been determined

Effects of platelets activated by different agonists on fibrin formation and thrombin generation

Activated platelets possess procoagulant activity expressing on their surface phosphatidylserine (PS), a substrate for assembling coagulation complexes. We examined the effects of platelets activated by different agonists on fibrin formation and thrombin generation and compared these effects with each other and with PS expression. Modified plasma recalcification assay was developed to assess platelet effects on fibrin formation. Washed human platelets were left intact or activated by A23187 ionophore, collagen, arachidonic acid, ADP or TRAP (Thrombin Receptor Activating Peptide) and spun down in 96-well plates. Plasma was then added, recalcified, and fibrin formation was monitored by light absorbance. Platelets prepared in the same way were tested for their effect on thrombin generation. PS expression was evaluated by flow cytometry using annexin V staining. Platelets significantly accelerated fibrin formation and thrombin generation. They shortened lag phase and increased maximum rate of plasma clotting, and increased peak and maximum rate of thrombin generation. In both tests platelets were presumably activated by endogenous thrombin formed in plasma after triggering coagulation reactions. However, pretreatment with exogenous agonists additionally increased platelet procoagulant activity. It reached the maximum after incubation with A23187, being lower with collagen and arachidonic acid and minimum with ADP and TRAP (the latter might be ineffective due to competition with endogenous thrombin). The effects of platelets activated by different agonists on fibrin formation and thrombin generation correlate with each other and correspond to PS expression on their surface

Development of KM-5 Hall effect thruster and its flight testing onboard GEO spacecraft “Express-A4”

The paper presents the outcomes of development of Keldysh Research Center (KeRC) KM-5 Hall effect thruster and experience obtained from the in-orbit exploiting of the thruster onboard Reshetnev's Scientific and Production Association of Applied Mechanics (NPO PM) “Express-A4” GEO communication spacecraft (SC). KM-5 is a multimode thruster with operational power range from 1 to 2.5 kW in contrast to other thrusters applied in space missions. It has high thrust characteristics. It makes possible solution of orbit raising tasks to geostationary orbit (GEO) for medium and heavy weight SC in addition to tasks of station keeping for geostationary SC already being solved by Hall-effect thrusters. Furthermore, a thruster with such performance can be an efficient choice as a main engine for small interplanetary probes