It was established that stable colloids of graphitic carbon nitride (GCN) can be obtained by relatively mild heat treatment of the bulk material in aqueous solutions of tetraethylammonium hydroxide. The colloids contain particles of average size of 40-45 nm with thicknesses of 6-8 nm. The band gap of the colloidal particles of GCN (3.45 eV) is significantly larger than E g of the bulk material (2.82 eV) as a result of spatial confinement of the charge carriers. The colloidal GCN is characterized by strong photoluminescence emitted in a broad spectral range with a maximum at 410-420 nm and a quantum yield of 21%-22%.Alongside graphene, MoS 2 , and a series of other layered materials graphitic carbon nitride (GCN) C 3 N 4 , which belongs to a class of long known organic polymers [1, 2], has attracted increased attention for researchers in recent years particularly in the region of heterogeneous catalysis and photocatalysis [1][2][3][4][5]. The monolayer of GCN is formed by heptazine heterocycles linked through the tertiary amine nitrogen atom into an infinite one-dimensional aromatic network. Layered GCN, formed by stacking pp interaction between individual monolayers, has semiconducting properties and is characterized by thermostability up to 650-700°C and chemical stability particularly in concentrated acids and alkalis [1,2]. The high stability, the low toxicity, and the fortunate disposition of the permitted energy bands of GCN, giving rise to its sensitivity to visible light and making it possible to realize simultaneously many reduction and oxidation processes involving photogenerated charge carriers, are the prerequisites for the swift development of research into the photocatalytic characteristics of GCN and systems based on it [1-5]. At the same time the effectiveness of many photocatalytic processes involving GCN is limited by its low specific surface area (~10 m 2 /g) on account of the fairly rigorous conditions of production in the course of the pyrolysis of melamine, dicyanodiamide, urea, and other precursors at 500-600°C [1,2]. In this connection searches are being made for methods of template synthesis of mesoporous GCN with a developed surface [3][4][5]. Simultaneously with this approaches are being developed for exfoliation of GCN [6-10] similar to the well-known methods for the exfoliation of graphite and its oxide or the dispersion of bulk GCN to nanosized particles [6,11,12] by extreme heat treatment [6,12] or by the action of oxidizing agents [11]. Such investigations today are sporadic, but the obtained results indicate the existence of a strong relationship between the size of the GCN particles and likewise the number of layers in their composition and the electrophysical and photophysical characteristics of the material [7,10,11,13,14]. This fact gives a special urgency to the search for new methods of dispersion of GCN and stabilization of its nanoparticles in colloidal solutions. The present work was devoted to investigation of the 0040-5760/14/5005-0291
Background.The COVID-19 epidemic in the Russian Federation, which began in March 2020, caused serious damage to health of the population and led to severe economic losses. By December 28, 2020, 3 078 035 cases of COVID-19 and 55 265 lethal outcomes were registered in the country. The population of all territorial subjects of the country is involved in the epidemic process of COVID-19. The severe epidemiological situation made it necessary to conduct an analysis to identify the factors that determine the high intensity of the epidemic process, as well as the population groups with the highest risk of SARS-CoV-2 infection. Aims to study the patterns of SARS-CoV-2 spread and the epidemiological features of the initial stage of the COVID-19 pandemic in the Russian Federation in 2020. Methods.An epidemiological analysis of the COVID-19 situation in the Russian Federation was carried out to determine the dynamics of morbidity, the gender proportion and age structure of patients, the proportion of hospitalized patients, the ratio of various forms of infection, the social and professional status of patients. Standard methods of descriptive statistics Microsoft Excel and STATISTICA 12.0 (StatSoft, USA) were used for statistical processing. The mean values were estimated with a 95% confidence interval [95% CI] (the exact Klopper Pearson method). Results.During the observation time (2020), several periods were identified in the dynamics of the new COVID-19 cases detection: the period of importation of SARS-CoV-2 and the increase in morbidity, the period of epidemic decline, the period of autumn growth, the period of sustained high incidence of COVID-19. It was found that people over 70 years of age are the group with the highest risk of infection and a more severe course of COVID-19. The presence of target contingents among social and professional groups of the population, which should include medical workers, retired person, employees of educational institutions, law enforcement agencies, transport, who require special attention and medical and social support, was shown. Conclusions.The analysis showed that the large-scale spread of COVID-19 requires in-depth epidemiological studies and the development of additional disease control measures, taking into account the dynamics of the incidence of this socially significant infection.
Aim. Identification of epidemiological patterns of the SARS-CoV-2 spread among the population of St. Petersburg during the one-year COVID-19 pandemic period.Materials and methods. The performed analysis focused on the dynamics of COVID-19 cases in St. Petersburg from 2/3/2020 to 4/4/2021 and on the gender-age profile of patients. The information about patients (age, gender, type of the disease, hospitalization, social, and occupational status) was obtained from the database containing the materials from statistical data form No. 058/u.Results. After one year, the dynamics of reported cases of COVID-19 in St. Petersburg shows two cycles of seasonal surge (spring and autumn-winter) and 8 epidemic periods. It has been found that there are no gender-age differences among COVID-19 patients, which can be seen from the relatively similar number of cases among men and women per 100,000 people in each age group during specific epidemic periods. The strong association between clinical manifestations of COVID-19 and the patients' age was detected: Severe cases were more frequently diagnosed in patients over 70 years, regardless of their gender identity. Based on the social and occupational status, the people who were most exposed to the COVID-19 epidemic process were retirees and people whose occupation was associated with health and safety of St. Petersburg. Among the COVID-19 patients, retirees accounted for 13.69% (men) and 17.67% (women). The proportion of healthcare workers was 3.67% (men) and 9.41% (women).Conclusion. It has been assumed that COVID-19 tends to be a seasonal disease featuring annual autumn-winter epidemic cycles. The study addressed prospects of preventive vaccination against COVID-19 in Russia and the importance of tracking the complications pathogenetically associated with the acute phase of the disease in the system of epidemiological surveillance.
Relevance. Hepatitis B is a global problem of global and Russian public health due to its high prevalence and the possibility of forming a chronic form of the disease with the development of cirrhosis and hepatocellular carcinoma. Aims. Assessment of the herd immunity to hepatitis B in the population of the Russian Federation in 2017‒2019.Materials and methods. The research was carried out at the Central Institute of Epidemiology within the framework of a large-scale program to assess herd immunity to hepatitis B in the population of the Russian Federation. The results of studies for the presence of anti-HBs in various subjects of the Russian Federation in 2017 to 2019, which were performed in accordance with MU 3.1.2943-11, were analyzed. Additionally, as a reference study in 2020, a survey of donors in Moscow (n = 427) was conducted for the presence of anti-HBs. Standard methods of descriptive statistics Microsoft Excel and STATISTICA 12.0 (StatSoft, USA) were used for statistical processing. The mean values were estimated taking into account the 95% confidence interval [95% CI] (according to the Klopper-Pearson method (exact method).Results. The average annual values of the proportion of persons with protective immunity against hepatitis B for 2017, 2018 and 2019 were 70.03%, 67.95% and 66.36%, respectively. Significant differences were revealed in the average values of the proportion of persons with a protective level of anti-HBs in the Federal Districts (FD): higher than the average Russian indicators were found in the Northwestern (74.2%), Southern (71.0%) and Far Eastern FD (70.7%). In 44 subjects of the Russian Federation during the observation period, the proportion of persons with protective immunity against hepatitis B was less than 60%.Conclusion. The necessity of optimizing the system of serological monitoring of post-vaccination immunity against hepatitis B is substantiated, which will increase the effectiveness of preventive measures nationwide
In the studied cohort, HCV subtypes 1b and 3a prevailed — 47,7% and 38,9%, respectively HCV genotype 2 was detected in 7,2% of cases and HCV subtype 1a — in 5,8% of cases. HCV genotype was not determined in 0,4% of patients. Difference between a frequency of detection of subtypes 1b and 3a of HCV in men and women were recorded. Subtype 3a HCV was determined in men in 44,8% of cases, and in women — in 31,7% of cases (p < 0.01). HCV subtype 1b in women was determined with a higher frequency (55,0%, р < 0, 01), than in men (41,8%).
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