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As a result of Russian military aggression in the south-eastern region of Ukraine, water supply pipes and structures of centralized water supply systems were destroyed, and therefore water supply was practically stopped. The solution to the problem can be the use of mobile water treatment stations which use local sources of water: canals, lakes, ponds, or underground water. A feature of water treatment technologies in the field is the need to reliably ensure the process of water disinfection. Existing water disinfection technologies have low efficiency, taking into account the growing number of chlorine-resistant microorganisms, therefore, the implementation of alternative methods of disinfection during water treatment is urgent. One of these methods is liquid disinfection by electric current discharge. The results of the research on disinfection of different types of surface water in Kyiv and water contaminated with E. coli (Escherichia coli (E. coli)) are described. The research was carried out on a laboratory setup with a circulation pump and an ejector-type reactor with integrated electrodes where a water-air mixture is formed through which an electric discharge passes. The discharges initiate the formation of various highly reactive chemicals such as radicals (OH•, H•, O•) and molecules (H2O2, H2, O2, O3). All physical and chemical processes that occur during discharge ensure the formation and action of short-term radicals and relatively long-term oxidants. The study of the influence of the concentration of microorganisms on the speed and completeness of water disinfection was carried out on technical (tap) water with the addition of washings from two tubes with test culture to the reaction tank, which provided the initial concentration of E. coli equal to 3.4∙106 CFU/cm3. Water treatment for 30 seconds reduced the number of microorganisms to 5.4∙104 CFU/cm3. After 1 minute of treatment this indicator decreased to 1.7∙102 and after 3 minutes the value of 5.2 CFU/cm3 was recorded in the samples, that is, the treated water had indicators of practically pure water. Experiments have proven the effectiveness of plasma disinfection for liquids with high concentration of microorganisms.

In this work, after X-ray and electron irradiation, the outcomes of the evaluation dynamic characteristics of interstitial atoms Sij , vacancy V, and O-complexes were evaluated to account for the annealing conditions to derive specific structural defects in the SiO2/Si wafer. A non-destructive method, which allows the determination of the internal friction difference ΔQ-1/Q-1 0 of the elastic vibration structure defect density Nd and the depth of the broken layer hb , is offered for the SiO2/Si wafer. The method was developed, the installation was designed and manufactured for the excitation and registration of damped bending resonant oscillations in a SiO2/Si disc-shaped wafer with a thickness hSiO2 ≈ 100 nm, his = 300÷500×103 nm, and diameter D = 60÷100×10-3 m to measure the structurally sensitive internal friction Q-1 . Measurement of the internal friction background Q-1 0 at harmonic frequencies f0 and f2 allowed us to experimentally determine the nodal lines of the oscillating disks.

In this work after X-ray irradiation outcomes of the evaluation of dynamic characteristics interstitial atoms Sij, vacancy V and O-complexes was applied for account of a condition of an annealing with the purpose of deriving specific structural defects in SiO2/Si wafer-plate. The nondestructive method, which is allow to determine from internal friction difference ΔQ-1/Q-1 0 of elastic vibrations structure defects density Nd and the depth of broken layer hb, is offered for SiO2/Si wafer-plates. 1. Introduction Defect annealing leads to a change in the shape of the internal friction (IF) temperature spectrum Q-1(T) [1]. IF method allows to set the spectrum of structural defects on the analysis of positions of maximums IF, on duration of relaxation time τ and on their deposit in attenuation of elastic vibrations [2]. A non-destructive method for the technological control of the structure defects by measuring internal friction (IF) and elastic modulus E after laser radiation was developed. 2. Experimental procedure Ultrasonic (US) pulse-phase method using USMV-LETI, modernized USMV-KNU and computerized “KERN-4” with frequencies f║ ≈ 1 MHz and f┴ ≈ 0,7 MHz, US invariant-polarization method for determining the effective acoustic μil and elastic constants Cijkl were used [3,4]. The measured velocity error was equal to ΔV/V = 0,5÷1,5%. The study of influence of structure defects on damping of vibrations in Si/SiO2 wafer-plates by the diameter of D = 100÷60 mm and by the thickness of hSiO2 ≈ 600 nm, hSi ≈ 470 000 nm, allows to estimate the degree of perfection of crystalline structure Metallography optical supervision of microstructure by means of the microscope ”LOMO MVT”, atomic-force microscopy (AFM) were used. 3. Results and discussion The quasi-longitudinal US velocity V║[001] = 5870 m/s, elastic modulus E001 = ρV║[001] 2 = 80,28 GPa for SiO2/Si from the oscillogram were determined. Temperature dependence of internal friction Q-1(T) in SiO2/Si wafer-plate p-type, doped with B, KDB-7.5(100) diameter D ≈ 76∙10-3 m, thickness hSi ≈ 460∙103 nm with SiO2 layer thickness hSiO2 ≈ 100 nm after X-ray irradiation with dose Dγ ≈ 102 Gy is showed. 4. Conclusions 1. The growth of internal friction maximum height QM -1 testifies the growth of the structural defects concentration n, and the broadening of internal friction maximum ΔQM -1 here represents the relaxation process of structural defects new types in SiO2/Si wafer-plate. 2. It was found that as the result of the structural defect annealing IF background Q0 -1 significantly decreases during measuring of IF temperature dependence Q-1(T), which indicates the improvement of SiO2/Si crystal structure. 3. The elastic modulus Е, the shear modulus G, Poisson coefficient μ, IF Q-1 are dependent from SiO2/Si wafer-plate anisotropy. 4. The value of IF background Q-1 0 after temperature T, mechanical treatments describes the changes of the elastic stress σi fields in SiO2/Si wafer-plate. 5. The study of vibrations of disk wafer-plate Si/SiO2 at different harmonic frequencies f0, f2 made it possible to develop the technique for determining the structural defects density nD for semiconductor wafers-substrates. 6. The relationship between IF Q-1 value, the logarithmic decrement of ultrasound damping δ and the dislocations density nD was established for disk-shaped semiconductor wafers-substrates. Acknowledgements This work has been supported by Ministry of Education and Science of Ukraine: Grant of the Ministry of Education and Science of Ukraine for perspective development of a scientific direction "Mathematical sciences and natural sciences" at Taras Shevchenko National University of Kyiv. References [1] Golovin I. S. 2012 Internal friction and mechanical spectroscopy of metal materials (Moscow: Publishing company MISIS). [2] Shpak A. P., Kunickiy Y. A. and Karbovskiy V. L. 2001 Cluster and nano structural materials (Kyiv: Academy periodicals). [3] Onanko A. P., Kuryliuk V. V., Onanko Y. A. et al. 2020 Peculiarity of elastic and inelastic properties of radiation cross-linked hydrogels. J. Nano- Electron. Phys. 12, № 4, 04026(5). DOI: https://doi.org/10.21272/jnep.12(4).04026. [4] Onanko A. P., Kuryliuk V. V., Onanko Y. A. et al. 2021 Features of inelastic and elastic characteristics of Si and SiO2/Si structures. J. Nano- Electron. Phys. 13, № 5, 05017(5). DOI: https://doi.org/10.21272/jnep.13(5).05017. Figure 1

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