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The shock-induced metal ejecta model based on the Richtmyer–Meshkov instability physics and developed for calculating the ejected mass of metal particles and their velocity distribution in the flow is applied to calculate the particle size distribution. The model is developed for metals transforming to a liquid state after the shock wave impact. It is shown that one has to know not only the density and surface tension of the liquid medium, but also the initial amplitude and wavelength of perturbations, as well as the shock wave profile for predicting the particle size spectrum in the case of liquid medium ejection. According to the theory developed, the particle size in the flow is largely determined by the perturbation wavelength than by the initial amplitude. The results are compared to experimental data on the size of nanoparticles ejected from narrow bands with initial perturbations on the free surface on tin and lead samples.

This paper presents the results of an experimental study of ejection and dispersion of a lead sample in vacuum after shock-wave loading and isentropic unloading using optoelectronic microscopy and photonic Doppler velocimetry. The dynamics and spectrum of predominantly dispersed particles are studied. Optical visualization is ensured by cutting out an 0.5-mm wide stream from the dispersed cloud using a diaphragm with a slit. The experiments are carried out in a sealed armored chamber. A 1- or 2.5-mm thick sample is loaded with a solid explosive through a metal substrate 1 and 2 mm in thickness. The shock wave intensity varies from about 23 to 38 GPa, and the pressure gradient behind the wave front ranges from 80 to 157 GPa/cm. After the loading, the lead is either in a liquid phase, in a solid phase, or in a mixture of both. It is shown that the particle size distributions of dispersed lead are different at different phase states.

The fragmentation of a drop of liquid (water, alcohol, glycerin) under the action of an air shock wave with a pressure of 0.2 and 3.2 atmg is studied experimentally and theoretically. The experiments are carried out using an air shock tube, and the liquid drop diameter is approximately 0.6 and 2 mm. The process is studied using high-speed video recording. Dispersed liquid particles from ≈5 μm in size are detected, liquid particle size distributions are plotted, and the particle velocities are determined. The experimental results are compared with the results of computational–theoretical estimation.

When studying the process of shock-induced ejecta, in particular when particle jets move in a gas or are caused by several shock waves, it is necessary to obtain experimental data on the time history of density in these jets starting from the moment of shock-wave arrival at the free surface of the sample. In this work, such measurements were performed using flash radiography with synchrotron radiation. In the experiments, one or two successive shock waves with a pressure of GPa arrived at the free surface of tin samples with a roughness Rz of 5, 20, and 60. Shock unloading occurred in vacuum or gas (air, helium, nitrogen) at initial pressures of atm. The paper presents the experimental setups and experimental data on the density dynamics in ejecta formed after the arrival of one and two successive shock waves at the free surface of samples in vacuum and gas media.

Two devices intended for copper cylindrical liner gasdynamic acceleration to velocities of 5–7 km/s using the chemicals explosion energy have been investigated. It has been demonstrated that the acceleration of quasi-isentropically and isentropically loaded liners under the conditions of high-level dynamics, symmetry of deposition, and suppression of shock-induced dusting is feasible.

This paper describes measurements of mass distribution along a microparticle jet with the use of synchrotron radiation (SR) from the VEPP-3 collider. The SR \"soft\" spectrum made it possible to measure microparticle jets of a record (minimum) density of about 1 mg/cm3. Simultaneous recording of microparticle jets using piezoelectric sensors made it possible to compare and mutually complement their readings.

The review is devoted to the most critical and yet least studied neurobiological effects of combined exposure to the radiation and gravitational factors in space exploration missions. The authors present the data of own multiyear investigations in this area, including the neurobiological responses of the central nervous system to synchronous combined exposure to ionizing radiation of varying quality modeling some types of galactic cosmic radiation and modeled microgravity in laboratory experiments with rats and primates using an original model. Neurobiological effects were explored in different levels of CNS organization from molecular to integrative (behavior of animals). The investigations point to the consequences of prolonged exposure, typological characteristics of animals, and complicated character of interaction of the factors under study.

We studied neurobiological effects of physical factors modeling interplanetary spaceflight conditions—microgravity (modeled by antiorthostatic suspension) and deep space radiation (modeled by quasi-chronic gamma irradiation and head irradiation by 12 C ions)—in Long-Evans male rats, taking into account typological characteristics of their higher nervous activity (HNA). We investigated behavioral changes, as well as the dynamics of EEG and neurochemical processes in the brain regions responsible for cognition and emotions (frontal cortex, thalamus, hypothalamus). We found differences in the effects of the above factors on orientation-exploratory activity and cognitive functions in control vs. exposed rats, as well as in animals of different HNA typologies (“excitable” vs. “inhibited”). These differences were underlain by the shift in the balance of the main inhibitory and excitatory neurotransmitters, GABA and glutamate, as well as in the dopaminergic system. Specifically, rats with the predominance of excitation learnt faster but were inferior to rats with the predominance of inhibition in retaining new skills. We also found some changes in the ratio of main EEG rhythms, elicited by experimental exposures.

A study of molecular mechanisms of the neurobiological effects of the combined exposure to 10‑day antiorthostatic suspension (AnOS), daily γ-irradiation, and irradiation with carbon ions in rats was carried out. Analysis of molecular changes in dopamine receptors of the hippocampus revealed changes in irradiated rats; in particular, increased expression of monoamine oxidase A, the substrates of which are serotonin, adrenaline, norepinephrine and histamine, was found. The spectral and amplitude–frequency EEG characteristics of rats after the specified influences were studied. Comparison of primary EEG results revealed a tendency towards a decrease in the frequencies of the first peak in irradiated rats regardless of rhythms. In irradiated animals, a tendency towards a decrease in the center frequencies and amplitudes of the most pronounced peak of the EEG spectrum and a decrease in the center frequency and amplitude within the delta rhythm of the maximum peak of the spectrum was observed. Increased anxiety and somewhat accelerated learning in the Morris tests and conditioned reflexes of active avoidance in the shuttle chamber were observed in the behavior of rats, which was consistent with changes in some metabolites of dopamine and serotonin in the hippocampus.

Long-term potentiation of monosynaptic projections from the ventral hippocampus to the medial prefrontal cortex was accompanied by increases in the power and synchronization of the θ rhythm in the cortex and hippocampus. Independently of changes in the power, increases in synchronization in the θ and δ ranges were seen with minimal expression of the θ rhythm.