The degree of salinity, the freezing point, and the amount of unfrozen water are key factors in predicting the temperature, humidity, and mechanical behavior of saline permafrost soils used in construction as foundations for buildings. The results of the experimental studies are presented and a method for calculation of the amount of unfrozen water in saline soils is proposed. The calculated and experimental data show good convergence for both sandy and clay soils of different salinity and water content.

Большое количество заторфованных грунтов на территории Российской Федерации, особенно в Арктической зоне, обуславливает необходимость изучения их температурного режима и теплофизических свойств.В этой работе приводятся экспериментальные данные по определению пористости, теплопроводности и количества незамерзшей воды песчаных грунтов с различной степенью содержания торфа.Экспериментальные исследования проводились на образцах с нарушенной структурой, которые были представлены слаборазложившимся торфом, среднезернистым речным песком и их различными смесями.Установлено, что степень заторфованности влияет на такие физические величины, как пористость, теплопроводность и количество незамерзшей воды.Для талых заторфованных песчаных грунтов при увеличении степени заторфованности значение пористости увеличивается.Как для талых, так и для мерзлых заторфованных песчаных грунтов теплопроводность с увеличением степени заторфованности уменьшается.При этом теплопроводность для мерзлых грунтов выше, чем для талых.Количество незамерзшей воды также зависит от степени заторфованности грунта

Using the molecular dynamics method, the role of many-particle interactions in the dynamics of low-energy ions in carbon nanotubes has been studied, highlighting the necessity of considering such interactions in corresponding molecular-dynamic calculations. The effect of elastic perturbations of the carbon nanotube wall on ion motion inside the nanotube channel has been investigated. It was found that ion energy losses decrease by a factor of 1.5 to 3 when taking into account the effect of the wall perturbation on ion motion as the ion velocity approaches the perturbation propagation velocity. Additionally, it was shown that the interaction between moving ions and wall perturbations of the carbon nanotube becomes more monotonic with a decrease in the magnitude of thermal fluctuations of the nanotube wall in terms of ion energy losses. Within the considered model, the stopping power of the electron gas bound to the atoms forming the carbon nanotube wall is small compared to the energy losses of ions due to elastic collisions with nanotube atoms.

The results of the development and implementation of a mathematical model for assessing the thermal influence of a building with a slab foundation on a compacted seasonally thawing (active) layer of permafrost with a system of air thermosiphons are presented. The data obtained show that the proposed solution makes it possible to ensure the formation of stable frozen conditions and the preservation of permafrost soils.

To generalize experimental data on the thermophysical characteristics of soils at positive and negative temperatures and reduce the scope of the experimental work, there is a need to systematize and expand the calculation of the thermal conductivity of soils. This paper proposes a method for calculating the thermal conductivity of fine soils in frozen and thawed states. The calculation models include a shell model combined with a model with interpenetrating components. The calculated thermal conductivity values were compared with experimental data.

Various nanostructured materials have been assessed for their ability to prevent bacterial growth. This paper reports the effects of intrinsic defects and ion irradiation on the antibacterial activity of multi-walled carbon nanotubes (MWNTs) against Escherichia coli (E. coli). The results suggested that 0.4 mg/ml of irradiated MWNTs (R-MWNTs) is the optimal dose for maximal inhibition, with an inhibition rate of 92.5 %. The bactericidal performance of R-MWNTs was confirmed by the dielectric conductivity, bacterial growth, and surface wettability measurements. E. coli was sensitive to R-MWNTs by forming a 35 mm inhibitory zone at a dose of 0.4 mg/ml. The length and diameter of the R-MWNTs were significantly reduced compared to the initial samples. As indicated by transmission electron microscopy, R-MWNTs can biologically separate the pathogen cells from their environ-ment, resulting in cell death. The enhancement of oxygen concentration after ion irradiation confirmed by energy dispersive spectroscopy. The induced defects on the surface of R-MWNTs were determined by Raman spec-troscopy. These results suggest that irradiated MWNTs could be an alternative antimicrobial material against infectious bacteria. The novel irradiation technique improved the antibacterial properties of the MWNTs high-lighting their potential applications in medical devices and industrial processes.

In the design of nuclear-optical converters (NOC) for detecting intense neutron fields (fluxes over 1015 cm–2·s–1), it is proposed to use hybrid gas ionization chambers (IC), in which electrical and optical neutron detecting methods are combined. For hybrid ICs, a technology is proposed for obtaining radiation-resistant and mechanically strong radiator materials capable of operating at temperatures of up to 1000 °C. This technology is based on solid-phase boron diffusion saturation of steel. It is shown that, at thermal neutron fluxes of 1×1010 n/(cm2·s) and higher, the integral intensity of argon luminescence as a result of ionization by α-particles and 7Li ions from layers of boride phases is sufficient for detection. The combination of optical and radiation properties of multicomponent fluoride glasses makes it possible to use them as condensed active substances of NOCs. Choosing the elemental and isotopic composition, it becomes possible to use fluoride glasses for multichannel neutron detection as well as to significantly simplify the procedure for separating gamma and neutron components of radiation under conditions of intense radiation fluxes. It has been experimentally shown that in irradiation with a neutron flux of 1×1017 n/(cm2·s), the intensity of Nd IR luminescence in glasses based on zirconium fluoride (ZBLAN) increases in the presence of Gd, which interacts with neutrons.

Multiwall carbon nanotubes (MWCNTs) with different initial diameters have been irradiated with accelerated He $${}^{+}$$ ions in the fluence range from $$2.5\times 10^{15}$$ to $$3\times 10^{16}$$ ion/cm $${}^{2}$$ . Raman scattering showed that the number of defects and amorphicity of MWCNTs rapidly increase with increasing fluence. The change in the mean diameter of MWCNTs depending on the irradiation fluence is shown. The change in the nature of this dependence for different initial diameters of the nanotubes is discussed. Sputtering of nanotubes has been simulated. It is shown that the value of the sputtering yield is in good agreement with the experimentally measured values of the mean diameter of the nanotubes.

A study of He+ ion irradiation influence on the wettability of the multi-walled carbon nanotubes is presented. Tablets of pressed nanotubes of two types with different diameters were prepared and irradiated by 80 keV He+ ions. Raman and X-ray photoelectron spectroscopies showed the differences in the rate of radiation-induced defect formation for different types of nanotubes. The formation of cross-links between the layers of nanotubes under ion irradiation was demonstrated by the molecular dynamics simulation. Contact angle changes drastically with an increase in the fluence for both types of nanotubes: at low fluences superhydrophobic surfaces are formed, with an increase in the fluence a significant reduction in contact angle is observed, especially for the nanotubes of smaller diameters.

In this work, we investigated the relationship between the structural properties of materials based on multi-walled carbon nanotubes and the vital activity of bacteria E. Coli strain M-17. In the course of research using scanning electron microscopy and Raman spectroscopy, the structure of nanotubes was analyzed. Nanotube samples were tested for wettability. The effect of carbon nanotube samples on the growth of the bacterial culture of E. Coli strain M-17 using spectrophotometry was investigated. As a result, it was shown that samples containing more disordered defective nanotubes on the surface are more hydrophilic and also show worse biocompatibility properties for E. Coli bacteria.

The biological interaction materials study is necessary when creating biocompatible implantable devices, including biosensors. Important criteria for their creation are the bactericidal properties of such materials. In this paper, we study the bacteria with vertically aligned carbon nanotubes interaction. In this work we examined the bioaffinity of multi-walled carbon nanotubes samples with E. Coli strain M17 bacteria. We synthesized carbon nanotubes with various structural features on the surface of silicon wafers. Then westudied of the wettability of the obtained samplesand tested bioactivity of E. Coli bacteria using spectrometry and photometry methods. It was found that E. Coli bacteria of strain M-17 demonstrated the best vital signs when interacting with the surfaces of hydrophobic samples of vertically oriented carbon nanotubes.

The effect of hypersonic waves excited by a heterostructure based on a silicon wafer with natural oxide on the survival of planaria after their decapitation has been experimentally investigated. The aim of the work was to study the physical and biological factors affecting the regeneration of planarians. The main object of study was a model organism – planaria Dugesia Tigrina. The planaria were decapitated, and then they were monitored by their habitat for a week. Identification and counting of microorganisms, bacterial microflora inoculation, temperature, and pH control were carried out. To explain the mechanisms that occur under the influence of hypersound, a mathematical model of the passage of hypersonic waves through a thin layer of water near the glass-liquid interface was developed. In the process of regeneration after decapitation of the experimental group, it was found that in the experimental group exposed to hypersound, the survival of planaria was 60% higher than in the control. It was shown that in an aqueous medium along the glass-water interface, hypersonic propagation occurs with less attenuation than in the water column. This leads to a waveguide effect and improved transmission of hypersonic effects to the studied organisms.

In this work, the formation of defects during the ionic modification of carbon nanotubes was studied. It was shown that during the ionic modification of multiwalled carbon nanotubes, the defect formation mechanism is reduced not only to the formation of recoil atoms by ions, but also due to the thermal peak. It can be seen that the radial distribution function for the irradiated nanotube is significantly different from the radial distribution function of a heated 4000 K nanotube. In addition, disorder has a special character: in the case of ion irradiation, in contrast to heating.

The propagation of wave packets of quantum particles through porous structures in thin semi-transparent films is studied. Numerical solution of the nonstationary Schrödinger equation is used in two-dimensional (for slits) and three-dimensional (round holes) cases. The transmission coefficient of quantum particles is compared with that of classical particles with the same density distribution. The vortex motion of the flux density having a hydrodynamic analog is studied. A variant of the “quantum caustic” is considered upon scattering of the particle wave packet at an obstacle.