Bismuth films are interesting objects for research because of the many effects occurring when the film thickness is less than 70 nm. The electronic band structure changes significantly depending on ...the film thickness. Consequently, by changing the film thickness, it is possible to control the physical properties of the material. The purpose of this paper is to give a brief description of the basic structural and physical properties of bismuth films. The structural properties, namely, morphology, roughness, nanoparticle size, and texture, are discussed first, followed by a description of the transport properties and the band structure. The transport properties are described using the semi-metal–semiconductor transition, which is associated with the quantum size effect. In addition, an important characteristic is a two-channel model, which allows describing the change in resistivity with temperature. The band structure of bismuth films is the most interesting part due to the anomalous effects for which there is still no unambiguous explanation. These effects include anomalous spin polarization, nontrivial topology, and zone changes near the edge of the film.
We present a method for the quantitative determination of the Agidol-1 antioxidant additive in fuels for jet engines in concentrations of 0.001–0.006 wt % by HPLC after its preconcentration by ...extraction with methanol. The ratio of fuel-to-methanol-to-water in extraction is optimized. Chromatographic separation was performed on a Kromasil C18 reversed-phase column, upon isocratic elution with a mixture of acetonitrile–water (60 : 40) and UV detection at a wavelength of 210 nm. The data were processed using the Turbochrom software.
In premature babies, plastic changes develop in the neural retina, which, depending on the severity of retinopathy of prematurity (ROP), are a manifestation of adaptive or non-adaptive plasticity. In ...various experimental studies on animal ROP models, the conditioning effects of intermittent white light stimulation and various mechanisms of the positive effect of red and ultraviolet radiation on the plasticity of the retina have been demonstrated, which allows phototherapy to be considered as a promising modifying treatment for ROP supplementing the main therapy. Taking into account that light-dependent processes are involved in the pathogenesis of ROP, we also hypothesize that fractal phototherapy with complex-structured optical stimuli, as a method of activating adaptive neuroplasticity, can be most effective in the complex of methods for preventing and treating ROP.
The structure of pseudoplacoid sensilla characteristic of Amphiesmenoptera was studied by SEM and TEM methods by the example of the mushroom-like sensilla in
Philopotamus montanus
Don., a member of ...the primitive family Philopotamidae. These sensilla were found to be different from the externally similar placoid sensilla in the presence of a socket-like depression and a sensillar stem arising from it. The expanded terminal part filled with the dendrites of the sensory neurons has numerous pores on its upper and lower surfaces. The sensillar dendrites have subterminal expansions filled with electron-transparent fluid, while their thin terminal parts have electron-dense central elements. The pseudoplacoid sensillum of
Ph. montanus
comprises three sensory neurons. The mushroom-like pseudoplacoid sensilla of
Ph. montanus
are compared with chemoreceptive sensilla of other insects.
Aim: to assess the relationship between colonization of the oral cavity with S. mutans and different genotypic characteristics and the degree of tooth decay in children.Materials and methods. 274 ...children aged 5 to 17 years (153 girls and 121 boys) who received a preventive dental checkup were included in the study. The dental caries experience was assessed by the DMFT index (number of decayed, missing due to caries, and filled teeth), according to WHO recommendations. The plaque was collected with sterile wooden toothpicks from the buccal gingival margin or from fissures of the first molars and placed in 1.5 mL Eppendorf tubes, and then plated on Mitis Salivarius Agar medium (HiMedia, India). 481 strains of S. mutans were selected for further study. DNA was extracted by an express method. Amplification was performed in the CFX-96 thermal cycler (Bio-Rad, USA). Serotyping was performed by multiplex PCR. PCR products were analyzed by gel electrophoresis in 1.5% agarose gel with ethidium bromide (10 mg/mL) manufactured by Helicon, Moscow, and visualized in UV light in transilluminator UVT1 by Biokom. Genotyping was performed according to the methodology (Saarela et al., 1996) with the oligonucleotide primer OPA-02 (5’-TGCCGAGCTG-3’). Strains of S. mutans were studied for the presence of the following genes: gtfB, spaP, cnm, fruA, gtfB, htrA, comE, mutA x(I), mutA (II), mutA (III), nlmAB (IV), adcA, Smu.399, Smu.583, Smu.761, Smu.940c, Smu.1449, Smu.2130.Results. S. mutans was isolated from all the examined children. Dental decay was detected in 82.4% of the children. Among the strains studied, all 4 serotypes were found: in children with a DMFT = 0 only serotypes k and f were detected; the predominant serotype in children with tooth decay was serotype c (74.7%). 19 genotypes of S. mutans were identified. In children without caries (DMFT = 0), S. mutans did not contain the genes spaP, comE, adcA, Smu.2130, Smu.1449, gtfB, htrA. With the increase in the DMFT index, the frequency of their detection increased. 9 genotypes of S. mutans had all 7 virulence factors. In 94.9% of children colonized by these “virulent” genotypes, high DMFT index scores were observed.Conclusion. The data obtained indicate that only a limited number of specific strains have a cariogenic potential. Strains of S. mutans belonging to serotypes e and c with a combination of virulence genes spaP, gtfB, comE, adcA, Smu.2130, Smu.1449, and htrA were isolated from children with tooth decay. Strains without these factors did not cause any damage to the teeth. The degree of tooth decay increases with colonization by several genotypes with the combination of virulence factors described above.
The complexes of precursor with pentadentate Salten ligand has been shown to have high-spin state (
S
= 5/2) in a single crystal and polycrystalline phase and contain both high-spin and low-spin (
S
...= 1/2) fractions in vitrified acetonitrile solutions. A correlation between ESR spectrum shape and crystallinity degree has been tracked for polycrystalline phase. The majority of complexes in crystals has been found to form exchange-coupled clusters. The ESR spectra of vitrified solutions have shown several types of high-spin centers and two kinds of low-spin complexes with different g-factors. On the basis of quantum chemical calculations, conclusion was drawn for the most likely structural form of the precursor in single crystal and polycrystalline samples and possible supramolecular associates in frozen solutions.
Objective was to investigate the SARS-CoV-2 collective immunity status of the population of Belarus within the context of the COVID-19 pandemic. Materials and methods. The work was carried out ...according to the methodology for assessing SARS-CoV-2 population immunity, developed by Rospotrebnadzor Russia and the Ministry of Health of Belarus with the participation of the St. Petersburg Pasteur Institute, taking into account WHO recommendations. The Bioethics Committee of Belarus and the local ethics committee of the St. Petersburg Pasteur Institute approved the study. Selection of participants was carried out using a questionnaire method and online technology (internet, cloud server). Volunteers were randomized into seven age groups (years of age): 1–17; 18–29; 30–39; 40–49; 50–59; 60–69; and 70+. Regional randomization ensured proportional representation of volunteers from each region, and no more than 30 people were included from one enterprise. In accordance with manufacturer instructions, blood plasma samples were analyzed for: IgG antibodies (Abs) to the SARS-CoV-2 nucleocapsid (Nc) using a quantitative ELISA test system; and IgG Abs to the receptor binding domain (RBD) of the SARS-CoV-2 S (spike) surface glycoprotein using a qualitative ELISA test system. Statistical processing was carried out using Excel 2010 and other software. Statistical differences were designated as significant when p 0.05, unless otherwise indicated. Results. The level of seroprevalence, in terms of Abs to Nc among the Belarusian population, was 38.4% (95% CI 37.6–45.4). The highest Ab levels were found among individuals in older age groups (50-70+ years old). The lowest were found in children 1–17 years old and in young people 18–39 years old The distribution of seroprevalence across Belarusian regions was relatively homogeneous, with the exception of the Minsk Region, where a statistically significant decrease in the indicator was noted. In terms of profession, the largest share of seropositive individuals was found among transportation workers; the smallest was found in business. The moderate COVID-19 incidence has not led to a dramatic increase in the number of contacts. The base reproduction number (R0) was 1.3. In the Republic of Belarus, there was a moderate level of asymptomatic COVID-19 among seropositive individuals (45.3% 95% CI 44.0–46.7). This form of infection was observed most often among children aged 1–17 years old (65.0% 95% CI 61.3–68.6). In parallel with seroprevalence assessment, SARS-CoV-2 vaccination was carried out. We used two vaccines: Gam-COVID-Vac (also known as Sputnik V, developed by Gamaleya National Center for Epidemiology and Microbiology, Russia); and BBIBP-CorV (Sinopharm, PRC). Vaccination against SARS-CoV-2 was accompanied by an increase in the level of anti-RBD Abs (95% 95% CI 94.7–96.7). Taking into account the vaccination of a subset of the population with BBIBP-CorV, the overall herd immunity, inferred from the analyzed indicators (presence of anti-Nc or anti-RBD Abs), was 47.1% (95% CI 46.3–48.0). Conclusion. COVID-19 in Belarus was characterized by a moderately pronounced course of the epidemic process. The threshold level of herd immunity to SARS-CoV-2 has not yet been reached, as a result of which the conditions for progression of the epidemic remain.
The first case of COVID-19 was diagnosed in St. Petersburg on March 2, 2020; the period of increase in the incidence lasted for 10 weeks, the maximum rates were recorded in mid-May, and subsequently ...there was a statistically significant decrease in the incidence.
Objective:
to determine the level and structure of community immunity to SARS-CoV-2 among the population of St. Petersburg during the period of intensive spread of COVID-19.
Materials and methods.
Selection of volunteers for the study was carried out through interviewing and randomization. The exclusion criterion was active COVID-19 infection at the time of the survey. 2713 people aged 1 to 70 years and above were examined for the presence of specific antibodies to SARS-CoV-2. Antibodies were detected by enzyme immunoassay.
Results and discussion
. Studies have shown that in St. Petersburg, in the active phase of COVID-19 epidemic, there was a moderate seroprevalence to SARS-CoV-2, which amounted to 26 %, against the background of a high frequency (84.5 %) of asymptomatic infection in seropositive individuals who did not have a history of COVID-19 disease, positive PCR result and ARI symptoms on the day of examination. The maximum indicators of herd immunity were established in children 1–6 years old (31.1 %), 7–13 years old (37.7 %) and people over 70 years old (30.4 %). Differences in the level of seroprevalence in the age groups of 18–49 years are statistically significant. The highest level of seroprevalence was found among the unemployed (29.7 %), healthcare workers (27.1 %), education sector (26.4 %) and business sector personnel (25 %). In convalescents, COVID-19 antibodies are produced in 75 % of cases. In individuals with positive result of PCR analysis carried out earlier, antibodies are detected in 70 % of the cases. The results of the study of herd immunity to SARS-CoV-2 are essential to forecast the development of the epidemiological situation, as well as to plan measures for specific and non-specific prevention of COVID-19.
In this paper, a numerical study of the formation of nitrogen oxides in the combustion chamber based on the model created by Mitchellom and Terbellom. The distribution of furnace temperature and the ...concentration of nitrogen oxides, as well as a comparison of numerical results with the data of field experiment.
In the meantime, search for environmentally friendly renewable energy sources alternative to fossil fuel has been driven by energy security challenges including limited availability of fuel and ...energy price fluctuations. Therefore herbal perennial grasses with their rapid growth and prominent biomass yield increasingly make it a favorite choice as a valuable agricultural crop usable for cellulosic ethanol production. As an example, the genus Miscanthus Anderss. (silvergrass) comprises ca. 14–20 species including M. sacchariflorus (Maxim.) Hack., M. sinensis Anderss., M. purpurascens Anderss, and M. × giganteus, which appear to be an almost inexhaustible source of sustainable raw material, and several Miscanthus species were investigated as a potential biofuel energy crop with commercially viable way of its producing. Introduction and investigation of Miscanthus species were initiated in the Central Siberian Botanical Garden of the Siberian Branch of the Russian Academy of Sciences (CSBG SB RAS, Novosibirsk, Russia) based on the grass and ornamental plant collection in the late 1990s. The paper objective is studying the biological traits of three Miscanthus species introduced into the CSBG SB RAS, selection and genetic identification of cultivars and varieties as the most perspective agricultural crop. To evaluate the potential crop yield and selection prospects of Miscanthus species being competitive as a valuable biofuel energy crop, the authors have estimated seasonal rhythms of model species development in the continental climate conditions of West Siberia. The article characterizes different Miscanthus varieties obtained either by the ex situ or in situ methods; presents the biochemical analysis of plant material and molecular identification of three Miscanthus species introduced into the CSBG SB RAS. The seasonal development analysis of three selected varieties of Miscanthus (M. sacchariflorus, M. sinensis, and M. purpurascens) proved the hydrometeorological conditions to be advantageous for prominent biomass yield, e. g. contributory to use Miscanthus in West Siberia as an easy to grow cellulose-rich grass. Molecular markers applicable in DNA-identification and genetic passportization of Miscanthus varieties have been established, which are perspective as such an economically available plant material as alternative non-woody source of cellulose.
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