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This paper presents a description of the modernized detonation driven shock tube DDST-M, in which conditions that simulate the entry of spacecraft into the Earth's atmosphere at the super orbital velocity (11.2 km/s) are achieved. The modernization consists in the inclusion of an additional element in the shock tube design - the prechamber, which separates the end wall of the tube with the igniter from the main volume by the perforated disc. The presence of the prechamber increases the energy efficiency of the facility, primarily due to a more complete combustion of the combustible mixture in the high-pressure chamber, which makes it possible to obtain higher shock wave velocities in the low-pressure chamber. A series of experiments was carried out to study the radiation characteristics of high temperature air in the range of shock wave velocities VSW = 4.2 ÷ 11.4 km/s and initial gas pressures p0 = 0.25 ÷ 10 Torr. Analysis of the obtained data made it possible to distinguish the features of the radiation in different parts of the spectrum depending on the shock wave velocity and the initial gas pressure. The measurement results are compared with the results of other studies.

The emission spectra of oxygen behind the front of a strong shock wave have been studied in the shock wave velocity ranges of 5.7—7.4 and 8.1—10.0 km/s at pressures before the wave front of 1.0 and 0.25 Torr. Time-integrated sweeps of radiation in a wide spectral range of 200—675 nm as well as temporal oscillograms of oxygen radiation have been obtained. An analysis of the obtained panoramic spectra shows that at low velocities of the shock wave, the system of Schumann—Runge molecular bands dominates in the emission spectrum. An increase in the shock wave velocity leads to the appearance of intense atomic lines in the emission spectrum. The peculiarities of temporal oscillograms for the most typical spectral lines, such as radiation of molecular oxygen at a wavelength of 213 nm (Schumann—Runge system) and radiation of atomic oxygen at wavelengths of 394 and 645 nm, are highlighted.

The Letter to Editor presents an analysis of some sections of the clinical guidelines «Diseases and conditions associated with iodine deficiency» published in No. 3 of the journal «Problems of Endocrinology» for 2021. In particular, the discussion deals with the coding of thyroid diseases according to ICD-10, depending on the iodine status of the population of constituent entities of the Russian Federation, as well as issues of diagnosis and treatment, such as «verification» of goiter detected by palpation, or treatment of the vast majority of children, adolescents and adults with potassium iodide. The obstacles to the epidemiological assessment of the iodine status of the population when examining schoolchildren are discussed separately, in connection with the introduction in 2020 of the new regulation, which requires the mandatory use of iodized salt for cooking in school canteens throughout the country.

Abstract The relationship between the structure and properties of nanoscale conductometric sensors based on binary mixtures of metal oxides in the detection of reducing gases in the environment is considered. The sensory effect in such systems is determined by the chemisorption of oxygen molecules and the detected gas on the surface of metal oxide catalytically active particles, the transfer of the reaction products to electron-rich nanoparticles, and subsequent reactions. Particular attention is paid to the doping of nanoparticles of the sensitive layer. In particular, the effect of doping on the concentration of oxygen vacancies, the activity of oxygen centers, and the adsorption properties of nanoparticles is discussed. In addition, the role of heterogeneous contacts is analyzed.

A new simplified kinetic model of kerosene combustion, which can be included in the complex modeling of various gas-dynamic flows, is developed. The model is based on the use of n-decane as a substitute for kerosene and contains 24 components that are involved in 25 chemical reactions describing the ignition of kerosene at both high and low temperatures. The proposed model is tested by comparing the calculation results with the available experimental data on measuring the ignition delay time in shock tubes in a wide range of temperatures and pressures.

Emission spectra of argon behind the front of a strong shock wave are studied in the range of shock-wave velocities of 4.6–8.3 km/s and pressures before the wave front of 0.25–5.00 Torr. Time-integrated sweeps of radiation in a wide spectral range from the ultraviolet to infrared (190–1100 nm) and time dependences of the argon radiation intensity at wavelengths of 420, 532.8, and 740 nm are obtained. Three characteristic stages of the temporal evolution of the emission lines are defined. The dependences of the duration and intensity of the emission lines on the initial gas pressure and shock-wave velocity are established. Data are obtained on the background radiation intensity and can be used to separate the intensities of certain argon-atom lines from the total radiation.

An experimental investigation has been conducted into the pyrolysis of typical medical waste components in a fixed-bed reactor with a view to obtaining detailed information on the process characteristics. It is shown that the main loss of the mass of the mixture of chlorine-containing medical wastes occurs in two stages. The first stage which finishes at a temperature of about 400°C is characterized by the discharge of pyrolysis water and gas which contains hydrogen chlorine. At the second stage, at a temperature from 400 to 500°C, there is a discharge of the main part of volatile substances that are largely made up of pyrolytic oil. An environmentally safe and cost-effective method of solving the problem of medical waste disposal based on its two-stage pyrolysis has been proposed. The method includes the removal of chlorine-containing components from medical waste before the thermal degradation of their organic part, which, in practice, excludes the possibility of formation of highly toxic chlorine-containing substances.

The experimental data on methods for the preparation of sorbent systems containing crown ethers and their complexing properties with cations of some radioactive and heavy metals were summarized and analyzed. The sorbents in which crown ethers are covalently bonded with the organic or inorganic substrate were shown to be more stable in the treatment of municipal and industrial wastewater from radionuclides and heavy metals. The key factor that determines the efficiency of cation adsorption by crown ether is the fit between the cation size and the cavity diameter of the crown ether.

In recent years, significant progress has been made at the global level in eliminating of iodine deficiency. However, until recently, there has been a gap in methods for estimating iodine intake with industrially processed foods (IPF) produced with iodized salt (IS). The aim of this work was to study the iodine consumption with IPF and kitchen salt by the adult population and pregnant women in Armenia and Moldova. Material and methods. For modeling iodine consumption, a special matrix based on MS Excel spreadsheets was used, into which data on the average per capita daily consumption of the main IPF, salt content in IPF, the share of IPF produced with IS in the total volume of their consumption, percentage of households using IS, and the iodine content in salt according to the national standard were entered. Results and discussion. The estimated average daily salt consumption per capita of the adult population of Armenia was 10.6 g. Due to the use of IS in 93% of households and in the production of 82% of bakery products, 7% of cheese, 83% of meat products, 44% of canned vegetables and 5% of pasta, iodine intake in adults was 149% of the recommended daily allowance (RDA). Bakery products and iodized kitchen salt were the main sources of iodine (66 and 70% of the RDA respectively), and the share of other IPF did not exceed 13%. In Moldova, salt consumption was 11.9 g per day. Due to the use of IS for the production of 50% bakery products, 12% of canned vegetables and 20% of pasta, iodine consumption in adults in Moldova amounted to 74% of RDA almost entirely due to bakery products and kitchen salt (37 and 35% of the RDA respectively). The median urinary iodine concentration indicated adequate iodine intake in both countries and was significantly higher in Armenia (242 μg/L) than in Moldova (136 μg/L). A planned 30% reduction in salt intake may lead to an inadequate reduction in iodine intake in pregnant women. Conclusion. Adequate iodine intake among the adult population of Armenia and Moldova is ensured mainly through the use of IS in households and in the production of bakery products.

The sorption of copper and lead ions by sorbents based on 15-crown-5 and 18-crown-6 esters and their benzosubstituted analogs chemically bonded to porous mineral substrates under the action of gamma radiation is considered. The influence of various parameters on the efficiency of metal sorption from aqueous solutions is studied. The correspondence between the ability of the sorbent to absorb metal ions and the size of the cavity of the crown ether (CE) is shown, which determines the high level of selectivity of such sorbents. Indeed, sorbents based on 18-crown-6 ether have a significantly higher sorption capacity in relation to lead, while 15-crown-5 ether is more effective for the sorption of copper ions. The effect of the radiation dose rate and the time of holding the sorbent in a salt solution on the amount of sorbed metal is studied.

A software package consisting of the TETRAN-PRO and the COND-KINET-1 proprietary computer codes, as well as computational methods and models they are based on, is described. The TETRAN-PRO code calculates the composition and thermodynamic properties of a multicomponent reacting system under thermodynamic equilibrium conditions, including products of combustion or pyrolysis of organic and composite fuels. The difference of this code from similar ones is the use of the method of prevailing components, which is most effective as to convergence, computation time, and the range of parameters used. The code includes the necessary database of the original thermodynamic properties for 3000 individual substances. The TETRAN-PRO code’s capabilities are demonstrated by the results from calculation of mercury vapors' conversion in the combustion products of Kuznetsk and Berezovo coals. The COND-KINET-1 calculates the parameters of a condensation aerosol formed during the bulk condensation in a vapor-gas mixture flow. The process is described with a system of moment equations for the droplet size distribution function, which is closed by the equations of momentum and energy. A comprehensive approach, thermodynamic and kinetic, has been formulated to the description of the bulk condensation in multicomponent reacting systems based on the TETRAN-PRO and COND-KINET-1 codes. The approach’s capabilities are demonstrated by the example of numerically simulating the formation of environmentally dangerous submicron particles in burning coals according to the condensation mechanism. Data on the concentration and size distribution of the generated particles are obtained. The predicted data on the fractional composition of particles are compared with the experiment.

The initiation and stabilization of detonation combustion of kerosene vapor in a supersonic air flow entering an expanding axisymmetric nozzle with a coaxial central body is numerically studied. Calculations are based on a reduced kinetic model of combustion, which includes 68 reactions for 44 components. Enthalpy and entropy of components are determined using approximating polynomials from the NASA database. A hydrodynamic model is based on two-dimensional unsteady Euler equations for an axisymmetric flow of a multicomponent reacting gas. Calculations are performed using the Godunov finite-difference scheme and its $$\beta$$ -modification of improved accuracy on smooth solutions. The flow parameters that ensure the steady detonation combustion of kerosene vapor in the nozzle under consideration are determined. The detonation combustion of kerosene has higher thrust than hydrogen combustion, but is noticeably inferior with regard to specific thrust. The calculations are performed on the “Lomonosov" supercomputer at the Lomonosov Moscow State University.

Studying the symmetry of different systems allows one to formulate a variety of conclusions regarding their properties without knowing the detailed information about a particular system. The models of Brownian motors (ratchets) relate the spatial-temporal dependence of the potential energy of Brownian particles and the resulting ratchet effect. In this article, we use the symmetry description of ratchet systems to study the mechanisms of the influence of the spatial and (or) temporal asymmetry of a nanosystem on the average velocity of Brownian motors of the two main types - with fluctuating periodic potential energy and fluctuating force (the so-called pulsating and forced (or tilted) ratchets). We consider the overdamped motion of a Brownian particle in an unbiased force field, which is described by a periodic stepwise coordinate function, that undergoes dichotomous changes with time. The use of symmetry transformations and symmetry properties of Brownian motors made it possible to obtain compact analytical representations of the average velocity of pulsating and forced ratchets as a function of the parameters of the spatial and temporal asymmetries of the force fields. The fundamental difference between the dependences of the average velocity of the Brownian motors of these two types on the asymmetry parameters is revealed. For the pulsating Brownian motors, the directed motion of nanoparticles is absent in a spatially symmetric system regardless of the presence of temporal asymmetry; the motion appears in the presence of spatial asymmetry, and it is possible to obtain the motor stopping points by tuning the temporal asymmetry parameter of the control process. For the forced Brownian motors, it is the temporal asymmetry that permits the ratchet effect in spatially symmetric systems. For this reason, stopping points as a result of competition of spatial and temporal asymmetries are easier to realize precisely for the motors with fluctuating forces (forced ratchets). The results presented in this article were obtained by analyzing only general symmetry properties, without involving hidden symmetries of ratchet systems, therefore the results are also valid for inertial dynamics.

The urgency of the problem of endocrine ophthalmopathy (EOP) is currently in no doubt. This is due to the fact that relatively recently methods of objective assessment of the state of the eyeball and orbital tissues using ultrasound (ultrasound), computed tomography (CT) and magnetic resonance imaging (MRI) have appeared. At the same time, the etiology and pathogenesis of EOP are not well understood, which undoubtedly affects the validity and effectiveness of various treatment methods.

Radioactive iodine, flying out of the destroyed reactor of the Chernobyl nuclear power plant, like a corona virus quickly spread throughout Europe. Iodine deficiency in the regions of Ukraine, Belarus and Russia adjacent to nuclear power plants became a factor in increased uptake of radioactive iodine by the thyroid gland in children and after 5 years led to an epidemic of thyroid cancer. Optimal iodine intake could become a kind of vaccination, which sharply reduces the risk of developing thyroid cancer, as has happened after the accident at the Fukushima nuclear power plant in Japan. Endemic goiter was eliminated 50 years ago, but returned to the country in the early 1990s after the collapse of iodized salt production and has not been eliminated to this day due to the lack of a legislative framework for mandatory salt iodization. The actual average consumption of iodine by residents of Russia is from 40 to 80 mcg per day, which is 23 times less than the recommended norm. Mild and moderate iodine deficiency was detected throughout the Russian Federation, and it is more typical for the the rural population. The iodine deficiency has the greatest negative effect on the psychomotor development of the child during the critical period the first 1000 days of life from the moment of conception to the end of the second year of life. According to WHO, over the past 20 years, iodine deficiency has been eliminated in 115 countries of the world, and the number of iodine-deficient countries has dropped to 25, but Russia is still among them. We believe that after the COVID-19 pandemic, it will no longer be necessary to prove the need for effective support for the prevention of both infectious and non-infectious diseases, and the declared preventive direction of Russian medicine will indeed become such.Радиоактивный йод, вылетевший из разрушенного реактора Чернобыльской атомной электростанции, как коронавирус, быстро распространился по Европе. Дефицит йода в прилегавших к атомной электростанции областях Украины, Беларуси и России стал фактором повышенного захвата радиоактивного йода щитовидной железой у детей и через 5 лет привел у них к эпидемии рака щитовидной железы. Оптимальное потребление йода могло бы стать своеобразной вакцинацией, резко снижающей риск развития поражения щитовидной железы, как это случилось после аварии на атомной электростанции в Фукусиме (Япония). Эндемический зоб устранен 50 лет тому назад, но вернулся в нашу страну в начале 1990-х годов после прекращения выпуска йодированной соли и остается не устраненным до настоящего времени из-за отсутствия законодательной базы для обязательного йодирования соли. Фактическое среднее потребление йода жителями России составляет от 40 до 80 мкг в день, что в 23 раза меньше рекомендованной нормы. На всей территории Российской Федерации выявлен йодный дефицит легкой и средней тяжести, причем в большей мере он характерен для питания сельского населения. Наибольший негативный эффект на психомоторное развитие ребенка йодный дефицит оказывает в критический период первые 1000 дней жизни с момента зачатия до конца второго года жизни. По данным Всемирной организации здравоохранения, за последние 20 лет йодный дефицит устранен в 115 государствах мира, а количество йододефицитных стран снизилось до 25, но Россия по-прежнему входит в их число. Полагаем, что после пандемии COVID-19 не надо будет доказывать необходимость эффективной поддержки в России мероприятий по предупреждению как инфекционных, так и неинфекционных заболеваний, а декларируемое профилактическое направление отечественной медицины действительно станет таковым.