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Introduction. The COVID-19 pandemic was announced by WHO in February 2020. In the Kaliningrad region, the first case (imported) was registered in early March 2020, the beginning of the epidemic increase fell on the 14th week. 2020, and the peak incidence was reached in the 22nd week of the year, after which there was a steady decrease in the number of cases. The study of population immunity was carried out at the 32nd week during the period of the lowest level of intensity of the epidemic process.Purpose of the study. Assessment of the assessment of the level of population immunity to the SARS-CoV-2 virus among the population of the Kaliningrad region during the period of the epidemic incidence of the population of COVID-19.Materials and methods. The study was carried out as part of the first stage of the Rospotrebnadzor program to assess population immunity to SARS-CoV-2 among the population of the Russian Federation. The selection of volunteers for the study was carried out by a questionnaire survey and subsequent randomization. The analysis includes the results of a survey of 2675 people. The number of volunteers in age groups ranged from 314 to 493 people. The results obtained were processed by the methods of variation statistics.Results. The results obtained showed that the average seroprevalence in the population was 50.2%, while the highest seroprevalence was found in the child age group 1-17 years (66.9%) and among persons aged 18-29 (57.0). No significant gender differences were found (men – 48,3 ± 1,6%, women – 51,1 ± 1,1%). The distribution of the proportion of seropositive people in the settlements of the region varied from 33,9% to 59.6%. The largest share of seroprevalence in the representative samples was found among people engaged in art / creativity (55,3%), the smallest – among educational workers (42,0%). Among COVID-19 convalescents, the level of humoral immunity reached 94,6%. Most of the seropositive volunteers (95,2%) did not have any symptoms of COVID-19, that is, they belonged to the category of asymptomatic carriers.Output. The results of a survey of a representative cohort of volunteers in the Kaliningrad region showed that they are characterized by a high level of population immunity, which makes it possible to expect a decrease in.

A method of determining the lasing capacity of complex molecules is proposed. This is based on general theory of intramolecular excitation energy redistribution processes and quantum-chemical calculations of the electronic structure, oscillator strengths, and loss spectra in systems of triplet and singlet excited states. The nature of the forbidden and allowed excited states is determined and laws governing changes in the spectral and luminescence characteristics, essential for laser action are determined for a large class of benzoxazoles as a function of the molecular structure. Lasing compounds are identified and laser action is reported for new compounds in the ultraviolet.

The theory and parametrization of an iterative method of calculating the electron structure of molecules are presented. Use is made of the modified Mulliken equation for calculating the population of the atomic orbits, while group theory is employed for estimating the parameters. A comparison between the calculated and experimental ionization potentials of certain molecules confirms that the simple computing method here proposed yields reasonably satisfactory results.

Calculations of the energetic characteristics (the heat of atomization, the rotation barrier, and the ionization potential) and the dipole moments of several hydrocarbon molecules by the CNDO/BW method are discussed. The method gives a good description of these properties and correctly describes the structure of certain molecules (hyperconjugation and change in the inductive effect). The results of calculations by various versions of the CNDO method are compared.

It is shown that the lasing ability of benzoxazoles depends on the structure of different types of their electronic energy levels. Compounds with Tππ*,S*ππ*,Tnπ*,and S*nπ* lower levels emit radiation. Stimulated emission was obtained from solutions of 2-phenylbenzoxazole derivatives in the shortest wavelength range of 319–360 nm and from solutions of 4-(benzoxazole-2-yl)–4'-phenylstilbene derivatives in the 426–446 nm range. A nonselective resonator pumped by λp=308 nm radiation from a pulse-periodic excimer laser was used. The laser action was achieved in two bands corresponding to the vibrational structure in the gain spectrum.

Lasing was observed in vapors of new organic compounds: para-terphenyl, 2-phenylbenzoxazole, 2-(n-tolyl) benzoxazole, 2-(n-methoxyphenyl) benzoxazole, 2-(n-dimethylaminophenyl) benzoxazole, 2-biphenylbenzoxazole, 2-(α-naphthyl) benzoxazole, and also 1,4-di(n-phenylethynyl) benzole, and paraquaterphenyl pumped transversely by XeCl* excimer laser radiation at λp = 308 nm. The lasing bands without tuning covered the 330–370 nm range. The shortest-wavelength maximum (333.5 nm) was observed for 2-(n-methoxyphenyl) benzoxazole. An analysis was made of the lasing ability of the molecules.

A study is made of the possibility of improving the laser properties of dyes pumped by the radiation of a copper-vapor laser, the choice of dye mixtures optimal from the point of view of producing stimulated emission, and the influence of the solvent on these properties, the aim being to obtain optimal energy parameters in an instrument based on a copper-vapor laser and an optical attachment.

The nature of theπ→π* transitions in the spectra of quinoxaline 1-N-oxides as compared with unoxidized quinoxalines was examined on the basis of an experimental, study and calculation by the Pariser-Parr-Pople configurational interaction method.

diagrammes Sc203--Ln20~," J. Solid State Chem., 26, 311-319 (1978). I0. M. J. Weber and T. E. Varitimos, "Optical spectra and intensities of Nd 3+ in YAI03," J. Appl. Phys., 42, 4996-5005 (1971) 0 Ii. P. A. Arsen'ev---and K. E. Binert, "Synthesis and optical properties of gadolinium alumihate single crystals doped with neodymium," Zh. Prikl. Spektrosk., 17, 1084-1087 (1972). 12. A. A. Kaminskii, A. O. Ivanov, S. E. Sarkisov, et al., "Combined studies on the spectral generation characteristics of LnAIO3 crystals containing Nd3+, '' Zh. Eksp. Teor. Fiz., 71, 984-1002 (1976).

The electronic structure, band characteristics, and interaction mechanism in aniline-nitrobenzene and nitrobenzene-phenol complexes are discussed. The discussion is based on the results from calculations by the Huckel and self-consistent field methods [7, 8].

The CNDO/2 method (complete neglect of differential overlap for valence electrons) [1] was used to calculate the models of molecules of toluene (I), nitrobenzene (II), o-nitrotoluene (III), and 2,4-dinitrotoluene (IV). The π- and σ-electronic structure of these molecules was discussed in the ground electronic state. A comparison of the total energies of various forms of III and IV molecules was used to determine the most likely pathway of conversion of the aci-nitro form into the nitro form and to estimate the activation energy of this process.

Quantum chemistry methods are used to calculate the cross section for stimulated emission σ(ν) and the Einstein coefficients B(ν) for several substituted forms of oxazole, oxadiazole, naphthalene, pyrene, and other molecules. It is shown that introduction of electron-donor and phenylethynyl substituents into molecules of heteroaromatic and aromatic compounds, respectively, increases considerably both σ(ν) and B(ν) and imparts lasing ability to nonlasing compounds. A criterion is established for the oscillator strength of an electronic transition which must be satisfied if a compound is to have the lasing ability.

Lasing was observed in pentane-stabilized vapors of 1,4-di[2-(5-phenyloxazolyl)]benzene (POPOP) and 1,4-di(benzoxazol-2'-yl)benzene (BOPBO) pumped by KrF* excimer laser radiation (λp = 248 nm). An investigation was made of the dependences of the threshold pump power density Wp.th on the pentane pressure, on temperature, and on the vapor pressure of the lasing substance at pump wavelengths λp = 248, 308, 337, and 350 nm. In the case of BOPBO the minimum threshold power density was Wp.th = 250 kW/cm2.

Nephrotoxicity and pharmacokinetics of gentamicin were studied on rats treated with the antibiotic for 30 days in doses of 6.25, 12.5 and 25 mg/kg administered daily. The pharmacokinetics of gentamicin and the time course of changes in the urea nitrogen levels of the blood serum were studied after the 1st, 5th, 8th and 30th injection. The analysis of the respective curves was used for calculation of the average integral values of the concentrations of the antibiotic (C) and urea nitrogen (E). After that the average integral values of these parameters ((CAVG and EAVG respectively) within the whole treatment couse with the use of every dose were calculated in the same way by using the curves of the dynamics of C and E changing. Comparison of the diagrams of E dependence on C for gentamicin and sisomycin showed that nephrotoxicity of sisomycin was 1.48 times higher than that of gentamicin.

The pharmacokinetics of ampicillin was studied in 30 children with diseases of the upper respiratory tracts. The data obtained with a single administration of anhydrous ampicillin in a dose of 25 mg/kg were estimated on one-compartment model. It was shown that the maximum antibiotic levels in the serum were attained in 1.52 hours and averaged to 4.56 micrograms/ml. The antibiotic half-life was 1.24 hours. The period of half-absorption of the antibiotic was 0.66 hours. Comparison of the experimental results with the literature data showed that the pharmacokinetic properties of anhydrous ampicillin and ampicillin trihydrate were close.

The pharmacokinetics of cephalexin monohydrate after its oral administration in a single dose was studied on rats and dogs. The analysis of the pharmacokinetic data obtained with the one-compartmental model showed that the rate of the antibiotic absorption in the rats was higher than that in the dogs. The periods of the cephalexin half-absorption and maximum concentration were 0.2 and 1.1 hour in the rats and 0.64 and 1.9 hours in the dogs respectively. The period of the antibiotic half-life was almost the same in both animal species. Selective localization of cephalexin in the kidney and liver tissues was noted. The antibiotic was mainly excreted by the kidneys (98.8 per cent for 24 hours).

The action of cefazolin on the pharmacokinetics and nephrotoxic effect of sisomicin was studied on Wistar rats. Sisomicin in doses of 12.5 and 25 mg/kg alone or in combination with cefazolin in doses of 90 and 360 mg/kg was administered intramuscularly to the animals daily for 16 days. It was shown that in both the doses cefazolin had no noticeable action on the level of the functional and morphological changes in the kidneys. Consequently, there were no significant changes in the levels of sisomicin in serum and the site of the nephrotoxic effect (cortical layer of the kidneys) and in the half-life of the aminoglycoside in the kidney cortical layer under the action of cefazolin. At the same time there was observed a marked individual variability of the levels of urea nitrogen and sisomicin in serum of the rats treated with the aminoglycoside alone or in combination with cefazolin. Analysis of the dependence of the nephrotoxic effect on concentration of sisomicin in serum after its use alone or in combination with cefazolin revealed that the changes in the individual intensity of the effect in all the cases were mainly induced by the changes in the sisomicin blood levels. Therefore, control of the blood levels of the aminoglycoside should provide prevention of the development of its nephrotoxic effect not only in monotherapy but also in the use of aminoglycosides in combination with cefazolin.