Обобщенная нуль-эллипсометрия в схеме "поляризатор-образец-анализатор"

The null-method in generalized ellipsometry with the use of the compensator-free “polarizer ‒ sample ‒ analyzer” scheme is considered for the case of s- and p-polarized incident light on an anisotropic system. Analytical expressions are given that connect the measured angular value — the analyzer azimuth at the detected radiation intensity minimum — with the (2x2) anisotropic Jones matrix elements. To determine the optical and geometric parameters of the studied anisotropic systems, it is proposed to use this value’s dependence on the sample orientation (azimuth). The method sensitivity is estimated. It was found that it is comparable to the sensitivity of the “polarizer‒compensator‒sample‒analyzer” scheme. A comparative analysis of this method and the known photometric method of generalized ellipsometry in the “polarizer-sample-analyzer” scheme based on measuring the dependence of the reflected light intensity on the sample azimuth at the fixed polarizer and analyzer positions is carried out. It is estimated that, to obtain the same sensitivity of these two methods, the one arc minute error in the proposed method corresponds to the 0.05% relative error in determining the energy reflection coefficient in the photometric method.

Age-related blood biochemical changes (lipid metabolism) in healthy young and mature men living under the North conditions

Metabolic disorders (dyslipidemias) are currently crucial since they develop cardiovascular diseases. The work was aimed at studying age dynamics and its correlation with severity of dyslipidemia in basic lipid metabolism variables (in different age groups). Materials and methods: Examinees were Caucasians born and permanently residing in Magadan region: 55 mature men and 147 young men (mean ages were 36.8±0.8 and 18.7±0.8 yr, respectively). Blood serum lipid metabolism was examined by colorimetric and photometric method using AU 680 (Beckman Coulter, USA). Results: The data of obtained lipidogram showed dependence of rise in all indicators on subjective older age with higher percentage of dyslipidemia and increase in calculated indices reflecting degree of the lipid profile atherogenicity. Conclusion: Overall, the North study revealed a safer lipid profile in group of younger men, while biochemical picture of older residents demonstrated increased values. Lipid atherogenicity is a very alarming factor in developing cardiovascular diseases, and a predictor of risks for metabolic syndrome.

PEGylated Graphene Quantum Dot Improved Cardiac Function in Rats with Myocardial Infarction: Morphological, Oxidative Stress, and Toxicological Evidences

Introduction. The biocompatibility and potential application of graphene-based nanomaterials in biomedicine have been documented. The effects of polyethylene glycol-graphene quantum dots (GQDs-PEG) on cardiac function in rats with myocardial infarction (MI) were examined. Methods. Wistar rats were randomly assigned to two main groups, each consisting of sham-Veh., MI-Veh., and MI+GQDs-PEG at doses of 5, 10, and 20 mg/kg. MI was induced by the closure of the left anterior descending (LAD) coronary artery. After MI, GQDs-PEG were injected at different doses IP every other day for two weeks. In the end, hemodynamic and heart contractility indices were assessed. The levels of myocardial MDA (malondialdehyde), SOD (superoxide dismutase), GPX (glutathione peroxidase), and TAC (total antioxidant capacity) were measured by the ELISA method. The serum ALP, ALT, AST, creatinine, and urea levels were measured using the photometric method. The infarct size was assessed by TTC staining. Results. GQDs-PEG decreased the infarct size at doses of 10 and 20 mg/kg and recovered the MI-induced reductions of +dp/dt max and -dp/dt max in the study groups. GQDs-PEG normalized systolic blood pressure and left ventricular systolic pressure reduction at the dose of 20 mg/kg in the MI group. Heart SOD, GPX, and TAC increased in the GQDs-PEG 10 and 20 groups. Almost no signs of toxic effects due to GQDs-PEG administration were observed on the liver and kidneys. Conclusions. The results provided clear evidence that GQDs-PEG improve cardiac performance and hemodynamic parameters in rats with MI by reducing oxidative stress. GQDs-PEG is proposed as a therapeutic target for the treatment of MI.

Identification of Vibrio cholerae O1 strains of the El Tor biovar sensitive to polymyxin B and their molecular genetic analysis

The aim of the work was the identification and genetic characterization of Vibrio cholerae O1 strains of the El Tor biovar sensitive to polymyxin B among isolates imported to Russia.Materials and methods. We used 56 toxigenic and non-toxigenic strains of V. cholerae isolated from patients and from the environmental samples on the territory of Russia in 1970-2020. Resistance to polymyxin B was determined according to MR4.2.2218-07. The ability of strains to form a biofilm on the abiotic surface was assessed by a photometric method. Nucleotide sequences of genes were determined using UGENE 1.32 and MEGA X software. Phylogenetic analysis and tree construction were performed using "maximum parsimony" method in MEGA X software.Results and discussion. Two genetically modified strains of V. cholerae O1 biovar El Tor, M1509 and 3265/80, which were imported to Russia from India in 2012 and 2014, respectively, were identified. The analysis of 12 genes responsible for the resistance of V. cholerae O1 biovar El Tor strains to polymyxin B demonstrated that these strains contain the allele of the carRS gene, which is typical for all strains of cholera vibrio sensitive to polymyxin B. Study of V. cholerae M1509 and 3265/80 phylogeny based on SNP analysis showed that they fall into the same cluster with isolates containing the carRS allele isolated in India (2015) and Bangladesh (2018). V. cholerae M1509 and 3256/8 strains had the ability to form a biofilm similar to those observed in other genetically modified strains of cholera vibrio included into analysis.Conclusion. Highly virulent strains of the cholera agent with altered diagnostically significant features are imported into Russia, which should be taken into account when identifying V. cholerae O1 biovar El Tor strains isolated from patients and environmental samples during monitoring studies.

Determination of histamine in fish and fish products: validation of photometric method

Topicality: The content of histamine in high concentrations causes a number of diseases that even lead to death, it is one of the indicators that characterizes the safety of fish and fish products. Therefore, the choice or development of a simple and inexpensive method for the determination of histamine content in fish and fish products is relevant. Objective: We confirmed the effectiveness of photometric method for the determination of histamine in fish and fish products by obtaining and analyzing validation characteristics. Results: Based on the results of validation, it has been substantiated and experimentally proved that the photometric method of quantitative determination of histamine can be correctly reproduced and is suitable for the quality control of measurements. The most acceptable results were obtained for histamine concentrations in the range from 50.0 ± 0.1 to 200.0 ± 0.5 mg/kg. The lower histamine concentrations are characterized by a higher percentage of total uncertainty, although it is also within acceptable values. Conclusions: Evaluation of the obtained validation characteristics indicates that this technique can be used to quantify the content of histamine in fish and fish products and is not inferior in accuracy and correctness to the method of high performance liquid chromatography.

INFLUENCE OF SUBCLINICAL KETOSIS IN COWS ON FORMATION OF COLOSTRAL IMMUNITY IN CALVES

The health of the newborn depends entirely on the state of the mother’s body throughout the pregnancy. Ensuring optimal conditions for keeping pregnant animals is based, first of all, on adequate feeding and ensuring the sanitary and hygienic conditions of the environment. The cow’s body undergoes a great load during the transition period, which begins 3 weeks before calving and lasts for six weeks. When the technology of feeding and housing is violated, during this period, metabolic disorders often occur in cows, which are manifested by increased production of ketones. It is known that the development of immunity in the early postnatal period in a calf largely depends on the timely feeding of colostrum. Maternal immunoglobulins from colostrum enter the systemic circulation of the newborn in the small intestine through the tubular system of epithelial cells by pinocytosis.The aim of the study is to study the effect of subclinical ketosis in mothers cows on the formation of colostral immunity in calves born from them.For the study, pregnant cows 3-6 years old were selected 3-7 days before delivery. Urine and blood samples were taken from the cows. In order to identify subclinical ketosis in cows, urine was tested for ketones. According to the results of the study, two groups of 10 animals were formed – in the first group (experimental) the level of ketone bodies in the urine ranged from 1.8 to 3.7 mmol/l, in the second group (control) ketones were not found in the urine. Immediately after calving, portions of colostrum were taken from the cows, and blood was taken from newborn calves a day after the first colostrum was fed. The content of immunoglobulins was studied in skim colostrum and in the blood serum of newborn calves. In the blood serum of day-old calves, the content of total protein was also determined by the biuret method, albumin – by the photometric method with bromcresol green.According to the results of the study, a decrease in the classes of immunoglobulins G, M and A was found in the blood serum of cows before calving by 19.1-23.5%, in colostrum – by 23.7-34.4%, and in the blood serum of day old calves – by 21.7-27.6%. The decrease in IgM concentration was determined to the greatest extent. Subclinical ketosis of mothers had practically no effect on the content of albumin in the blood of calves.

MICROBIOLOGICAL AND SANITARY - CHEMICAL CHARACTERISTICS OF WASTEWATER FROM PHARMACEUTICAL COMPANY

Aim. Оssessment of wastewater from a pharmaceutical company according to sanitary-microbiological and chemical indicators to determine the method of treatment and remediation of them from pollutants and pathogens. Methods. In sanitary and bacteriological studies, classical microbiological methods were used to determine the total microbial number of pathogenic bacteria. Determination of the concentration of ammonium, nitrite and nitrate in wastewater samples from a pharmaceutical company was carried out spectrophotometrically using the chemical reaction of ions to Nessler's reagent, Griss reagent, and phenol sulfide acid. The content of heavy metal ions was determined by the method of electrothermal AAS using the device "Saturn-2", by the photometric method using 4-aminoantipyrine – phenol, by the extraction-photometric method – by surfactants, by the method of infrared spectrometry – by petroleum hydrocarbons. Results. It was experimentally confirmed that the total microbial count in wastewater samples from a pharmaceutical company slightly exceeded the standard value. The BGKP index and the E. coli index were within the normal range. The pathogenic bacteria Salmonella moscow and Klebsiella pneumoniae were found in the wastewater of pharmaceutical company. The contamination of pharmaceutical stock can be judged by the 8.5 times excess of the concentration of ammonium ions in them compared to the MPC. The results of chemical analysis of wastewater samples from a pharmaceutical company indicate their multicomponent composition.Of the heavy metal ions, ions of zinc, copper, lead, hexavalent chromium and cadmium were mainly detected. With the exception of cadmium ions, the concentration of heavy metal ions was 1.4–7.2 times higher than the MPC norm. Anionic surfactants predominated in pharmaceutical stocks – their concentration was 8.2 ± 0.7 mg/dm3. The level of phenolic and oil pollution of wastewater was minimal in comparison with the content of anionic surfactants, which could be caused by the activity of aboriginal strains of bacteria-destructors with a high phenolic capacity. Conclusion. The results of sanitary-microbiological and chemical analysis of wastewaters of a pharmaceutical company indicate their multicomponent nature and environmental hazard – they contain pathogenic bacteria Salmonella moscow and Klebsiella pneumoniae and pollutants of various nature: heavy metal ions Cu (II), Cr (VI) and Pb (II) at a concentration of 36.0 ± 14 μg/dm3, 3.0 ± 0.4 μg/dm3 and 14.0 ± 0.7 μg/dm3, respectively, and organic pollutants – phenol, oil products and anionic surfactants at a concentration of 0.003 ± 0.0006 mg/dm3, 0.81 ± 0.05 mg/dm3 and 8.2 ± 0.7 mg/dm3, respectively. Werecommend to carry out a comprehensive purification of wastewater from a pharmaceutical company from phenol, heavy metal ions [Cu (II), Cr (VI), Zn (II)], oil products, anionic surfactants and pathogens.

A Study of the Extragalactic UV Radiation in Helix Nebula using GALEX

We have studied the ultraviolet sources using Galaxy Evolution Explorer medium imaging surveys in Helix Nebula and estimated UV fluxes by using aperture photometry in distant and near ultraviolet bands. The aperture photometric method produces reliable, accurate flux measurements and found inconsistent with the merged catalog of Galaxy Evolution Explorer. From the current results, the fluxes are consistent with brighter absolute magnitude up to 24.5 and the measurement error increases gradually to more than 50 % at the fainter magnitude side. Percentage of error in far UV is greater than near UV, due to the fact that brighter galaxies are more visible than the near UV sources. The diffuse UV contributors of zodiacal light, airglow contribution in the nebula were estimated. The total extragalactic UV radiation from the detected sources to the diffuse background in the nebula is of the order of 50 ± 14 photons cm-2sr-1s-1Å-1 in NUV band and 28 ±10 photons cm-2sr-1s-1Å-1 in FUV band. HIGHLIGHTS GALEX observations have the potential to find extragalactic UV sources Helix Nebula is first identified for distinct source detection Aperture photometric method can detect fainter sources up to the magnitude of 27 Extragalactic sources in the Helix nebula contribute to diffuse UV emission in the nebula GRAPHICAL ABSTRACT

APPLICATION OF PHOTOMETRY IN DETERMINING THE DUST MASS CONCENTRATION OF HARDWOODS

Given the carcinogenicity of hardwood dust, the aim of this study was to determine the effectiveness of the photometric method for different types of woodworking machines and its application in determining the mass concentration of inhalable dust for raw and dry hardwoods. In addition to the optical part of the device, the input part of the measuring device contains the Institute of Occupational Medicine (IOM) inhalable dust filter holder. This correlation of gravimetric and photometric methods in determining the dust mass concentration showed that photometry underestimates the mass concentration measured gravimetrically. The results of this study recommend the application of a correction factor 2 for a timber band saw and a correction factor 3 for circular saws in determining the mass concentration of hardwood dust by the photometric method. It was showed that photometry can be used if the correction factor of the optical device has been previously tested for specific wood processing place.