Репозиторий Университета

The local crystal/magnetic structures of the SrFe12−xInxO19 solid solutions (x = 0.1; 0.3; 0.6 and 1.2) were investigated using neutron powder diffraction. The measurements of the electric polarization for all investigated samples were carried out as a function of the external electric field. The presence of the ferroelectric and ferromagnetic ordering (dual ferroic ordering) in the SrFe12−xInxO19 hexaferrites at 300 K was found. This appearance contradicts to the conventional opinion describing their crystal structure (centrosymmetric space group P63/mmc (No. 194)). The reason for the existence of a spontaneous polarization (nonzero dipole moment) in the SrFe12−xInxO19 hexaferrites continues controversial. The crystal structure of the hexaferrites was considered both the centrosymmetric P63/mmc and non-centrosymmetric P63mc space groups. This fact made it possible to find a connection between the emerging dipole moment and not equal distortions of the neighbor oxygen polyhedral. The nature description of the nonzero dipole moment formation in a quasi-centrosymmetrical system of the In-substituted SrFe12−xInxO19 hexaferrites was presented based on the neutron diffraction data.

The local crystal/magnetic structures of the SrFe12−xInxO19 solid solutions (x = 0.1; 0.3; 0.6 and 1.2) were investigated using neutron powder diffraction. The measurements of the electric polarization for all investigated samples were carried out as a function of the external electric field. The presence of the ferroelectric and ferromagnetic ordering (dual ferroic ordering) in the SrFe12−xInxO19 hexaferrites at 300 K was found. This appearance contradicts to the conventional opinion describing their crystal structure (centrosymmetric space group P63/mmc (No. 194)). The reason for the existence of a spontaneous polarization (nonzero dipole moment) in the SrFe12−xInxO19 hexaferrites continues controversial. The crystal structure of the hexaferrites was considered both the centrosymmetric P63/mmc and non-centrosymmetric P63mc space groups. This fact made it possible to find a connection between the emerging dipole moment and not equal distortions of the neighbor oxygen polyhedral. The nature description of the nonzero dipole moment formation in a quasi-centrosymmetrical system of the In-substituted SrFe12−xInxO19 hexaferrites was presented based on the neutron diffraction data.

© 2021, The Author(s). Background: HIV infection is a major health problem in Russia. We aimed to assess HIV prevalence in different population groups and to compare the characteristics of 4th generation immunoassays from Abbott, Bio-Rad, Vector-Best, Diagnostic Systems, and Medical Biological Unit. Methods: The study included 4452 individuals from the general population (GP), 391 subjects at high risk of HIV infection (HR) and 699 with potentially interfering conditions. HIV positivity was confirmed by immunoblot and by HIV RNA, seroconversion and virus diversity panels were also used. HIV avidity was employed to assess recent infections. Results: The prevalence in GP was 0.40%, higher in males (0.62%) and in people aged < 40 years (0.58%). Patients attending dermo-venereal centers and drug users had a high prevalence (34.1 and 58.8%). Recent infections were diagnosed in 20% of GP and in 4.2% of HR. Assay sensitivity was 100% except for one false negative (99,54%, MBU). Specificity was 99.58–99.89% overall, but as low as 93.26% on HR (Vector-Best). Small differences on early seroconversion were recorded. Only the Abbott assay detected all samples on the viral diversity panel. Conclusion: HIV infection rate in the high-risk groups suggests that awareness and screening campaigns should be enhanced. Fourth generation assays are adequate but performance differences must be considered.

Background: Confinement due to COVID-19 has increased mental ill-health. Few studies unpack the risk and protective factors associated with mental ill-health and addictions that might inform future preparedness. Methods: Cross-sectional on-line survey with 37,810 Catalan residents aged 16+ years from 21 April to 20 May 2020 reporting prevalence of mental ill-health and substance use and associated coping strategies and behaviours. Results: Weighted prevalence of reported depression, anxiety and lack of mental well-being was, respectively, 23, 26, and 75%, each three-fold higher than before confinement. The use of prescribed hypnosedatives was two-fold and of non-prescribed hypnosedatives ten-fold higher than in 2018. Women, younger adults and students were considerably more likely, and older and retired people considerably less likely to report mental ill-health. High levels of social support, dedicating time to oneself, following a routine, and undertaking relaxing activities were associated with half the likelihood of reported mental ill-health. Worrying about problems living at home, the uncertainty of when normality would return, and job loss were associated with more than one and a half times the likelihood of mental ill-health. With the possible exception of moderately severe and severe depression, length of confinement had no association with reported mental ill-health. Conclusions: The trebling of psychiatric symptomatology might lead to either to under-identification of cases and treatment gap, or a saturation of mental health services if these are not matched with prevalence increases. Special attention is needed for the younger adult population. In the presence of potential new confinement, improved mental health literacy of evidence-based coping strategies and resilience building are urgently needed to mitigate mental ill-health.

© 2021 Mathematical models for complex systems under random fluctuations often certain uncertain parameters. However, quantifying model uncertainty for a stochastic differential equation with an α-stable Lévy process is still lacking. Here, we propose an approach to infer all the uncertain non-Gaussian parameters and other system parameters by minimizing the Hellinger distance over the parameter space. The Hellinger distance measures the similarity between an empirical probability density of non-Gaussian observations and a solution (as a probability density) of the associated nonlocal Fokker-Planck equation. Numerical experiments verify that our method is feasible for estimating single and multiple parameters. Meanwhile, we find an optimal estimation interval of the estimated parameters. This method is beneficial for extracting governing dynamical system models under non-Gaussian fluctuations, as in the study of abrupt climate changes in the Dansgaard-Oeschger events.

© 2021 Elsevier Ltd This review examines investigations into the functionalization of polysaccharides by substituents containing multiple (C[dbnd]C) bonds and thiol (SH) groups that are prone to (co)polymerization in the presence of thermal, redox and photoinitiators or Michael addition reactions. A comparative analysis of the approaches to grafting the mentioned substituents onto the polysaccharide macromolecules was conducted. The use of the modified polysaccharides for the design of the 3D structures, including for the development of the pore bearing matrixes of cells or scaffolds utilized in regenerative medicine was examined. These modified polymers were also examined toward the design of excipient matrixes in pharmacological compositions, including with controllable release of active pharmaceuticals, as wel as of antibacterial and antifungal agents and others. In addition, a few examples of the use of modified derivatives in other areas are given.

© 2021 Elsevier Ltd The functionalization of the bacterial cellulose (BC) surface with a chitosan biopolymer to expand the areas of possible applications of the modified BC is an important scientific task. The creation of such composites in the carbonic acid solutions that were performed in this work has several advantages in terms of being biocompatible and eco-friendly. Quantitative analysis of chitosan content in the composite was conducted by tritium-labeled chitosan radioactivity detection method and this showed three times increased chitosan loading. Different physicochemical methods showed successful incorporation of chitosan into the BC matrix and interaction with it through hydrogen bonds. Microscopy results showed that the chitosan coating with a thickness of around 10 nm was formed in the bulk of BC, covering each microfibril. It was found that the inner specific surface area increased 1.5 times on deposition of chitosan from the solutions in carbonic acid.

© 2021 Elsevier B.V. The Astrakhan region of Russia is endemic for the number of arboviruses. In this paper, we describe the results of the detection of the list of neglected arboviruses in the Astrakhan region for the 2018 season. For the purpose of the study in-house PCR assays for detection of 18 arboviruses have been developed and validated using arboviruses obtained from Russian State Collection of Viruses. Pools of ticks (n = 463) and mosquitoes (n = 312) as well as 420 samples of human patients sera have been collected and analyzed. Using developed multiplex real-time PCR assays we were able to detect RNA of eight arboviruses (Crimean-Congo hemorrhagic fever virus, Dhori (Batken strain) virus, Batai virus, Tahyna virus, Uukuniemi virus, Inkoo virus, Sindbis virus and West Nile fever virus). All discovered viruses are capable of infecting humans causing fever and in some cases severe forms with hemorrhagic or neurologic symptoms. From PCR-positive samples, we were able to recover one isolate each of Dhori (Batken strain) virus and Crimean-Congo hemorrhagic fever virus which were further characterized by next-generation sequencing. The genomic sequences of identified Dhori (Batken strain) virus strain represent the most complete genome of Batken virus strain among previously reported.

© 2020 Wiley Periodicals LLC A modern immunofluorescence analysis based on spectrally encoded microspheres has found numerous and constantly growing applications in disease diagnosis, environmental supervision, and fundamental science. Here we present an overview of microsphere-based methods of multiplex immunofluorescence analysis and consider such important parameters of beads, that are crucial in most microsphere-based immunoassays, as size distribution, fluorescence stability, magnetic properties, and particle material. The preparation methods of the microspheres with tunable diameter, the introduction of various types of fluorochromes, and magnetic particles into the microspheres are discussed in details. This review also addresses the advantages and disadvantages of different approaches to implement technically bead-based immunofluorescence analysis.

© 2021, Springer Science+Business Media, LLC, part of Springer Nature. A virtual element discretisation for the numerical approximation of the three-field formulation of linear poroelasticity introduced in R. Oyarzúa and R. Ruiz-Baier, (SIAM J. Numer. Anal.54 2951–2973, 2016) is proposed. The treatment is extended to include also the transient case. Appropriate poroelasticity projector operators are introduced and they assist in deriving energy bounds for the time-dependent discrete problem. Under standard assumptions on the computational domain, optimal a priori error estimates are established. These estimates are valid independently of the values assumed by the dilation modulus and the specific storage coefficient, implying that the formulation is locking-free. Furthermore, the accuracy of the method is verified numerically through a set of computational tests.

© 2020 The Author(s). Published by IOP Publishing Ltd Printed in the UK Graphene-based nano-porous materials (GNM) are potentially useful for all those applications needing a large specific surface area (SSA), typical of the bidimensional graphene, yet realized in the bulk dimensionality. Such applications include for instance gas storage and sorting, catalysis and electrochemical energy storage. While a reasonable control of the structure is achieved in micro-porous materials by using nano-micro particles as templates, the controlled production or even characterization of GNMs with porosity strictly at the nano-scale still raises issues. These are usually produced using dispersion of nano-flakes as precursors resulting in little control on the final structure, which in turn reflects in problems in the structural model building for computer simulations. In this work, we describe a strategy to build models for these materials with predetermined structural properties (SSA, density, porosity), which exploits molecular dynamics simulations, Monte Carlo methods and machine learning algorithms. Our strategy is inspired by the real synthesis process: starting from randomly distributed flakes, we include defects, perforation, structure deformation and edge saturation on the fly, and, after structural refinement, we obtain realistic models, with given structural features. We find relationships between the structural characteristics and size distributions of the starting flake suspension and the final structure, which can give indications for more efficient synthesis routes. We subsequently give a full characterization of the models versus H2 adsorption, from which we extract quantitative relationship between the structural parameters and the gravimetric density. Our results quantitatively clarify the role of surfaces and edges relative amount in determining the H2 adsorption, and suggest strategies to overcome the inherent physical limitations of these materials as adsorbers. We implemented the model building and analysis procedures in software tools, freely available upon request.

© 2020, Advanced Scientific Research. All rights reserved. In the modern world, acute respiratory viral infections are a widespread and socially significant disease. Having the similarity of structure, epidemiology and strong tropism to the respiratory tract, each causative agent of acute respiratory viral infection has its own characteristics. The most severe course with complications is characteristic of influenza. More than 200 viruses are known to cause acute respiratory viral infections. Their diversity is very great. This creates a situation when a person, having been ill with a disease caused by one virus, can immediately become infected with other viruses of this group and get sick again. For a year in the world, for an adult, 3-4 cases of the disease of acute respiratory viral infection occur. A child suffers from this infection 6-9 times during the year. 3.9 million deaths worldwide are associated with acute respiratory viral infections each year. Due to the enormous social significance of acute respiratory viral infection, the World Health Organization has launched the Battle against Respiratory Viruses initiative to combat it. Her prerequisites were problems with the treatment and prevention of acute respiratory viral infection. It is aimed at improving diagnostic methods to differentiate viral and bacterial infections at the earliest stages of the disease, developing effective antiviral drugs for the most common viruses and safe and effective stimulants of defense mechanisms in the body. It becomes clear that acute respiratory viral infections are a diverse group of infectious diseases of the respiratory tract that have similar developmental mechanisms, epidemiological and clinical characteristics. Given that these diseases have a high contagiousness, rapid spread, a significant number of complications, especially among people at risk, they require serious and lengthy research.

© 2020 Elsevier Ltd The purpose of this study is the mechanical characterization of the mid-to- old-age human anterior lens capsules (ALCs) obtained by capsulorhexis using Atomic Force Microscopy (AFM) and a nanoindenter at different spatial scales. The dependencies on the human age, presence or absence of pseudoexfoliation syndrome (PEX), and application of trypan blue staining during the surgery were analyzed. The measurements on both the anterior (AS) and epithelial (ES) sides of the ALC were conducted and the effect of cells present on the epithelial side was carefully accounted for. The ES of the ALC had a homogenous distribution of the Young's modulus over the surface as shown by the macroscale mapping with the nanoindenter and local AFM indentations, while the AS was more heterogeneous. Age-related changes were assessed in groups ranging from the mid-age (from 48 years) to old-age (up to 93 years). We found that the ES was always stiffer than the AS, and this difference decreased with age due to a gradual decrease in the Young's modulus of the ES and an increase in the modulus of the AS. No significant changes were found in the mechanical properties of ALCs of PEX patients versus the PEX-free group, as well as in the properties of the ALC with and without trypan blue staining.

© 2020 by the authors. Licensee MDPI, Basel, Switzerland. Web-surveys are one of the most popular forms of primary data collection used for various researches. However, mass surveys involve some challenges. It is required to consider different platforms and browsers, as well as different data transfer rates using connections in different regions of the country. Ensuring guaranteed data delivery in these conditions should determine the right choice of technologies for implementing web-surveys. The paper describes the solution to transfer a questionnaire to the client side in the form of an archive. This technological solution ensures independence from the data transfer rate and the stability of the communication connection with significant survey filling time. The conducted survey benefited the service of education psychologists under the federal Ministry of Education. School psychologists consciously took part in the survey, realizing the importance of their opinion for organizing and improving their professional activities. The desire to answer open-ended questions in detail created a part of the answers in the dataset, where there were several sentences about different aspects of professional activity. An important challenge of the problem is the Russian language, for which there are not as many tools as for the languages more widespread in the world. The survey involved 20,443 school psychologists from all regions of the Russian Federation, both from urban and rural areas. The answers did not contain spam, runaround answers, and so on as evidenced by the average response time. For the surveys, an authoring development tool DigitalPsyTools.ru was used. Dataset: http://dx.doi.org/10.17632/m32kz6jjcx.1 Dataset License: CC-BY-4.0.

© 2020 Elsevier B.V. This work proposes an original method for generating atomistic models of multi-branched and arbitrary-shaped seamless junctions of different nanostructures. Atomic frameworks of new hybrid systems with a wide variety of topological forms based on 1D and 2D structures can be obtained using this method. The topological diversity of generated hybrid systems is provided by the some features of the developed method. This method combines a triangulated nanomesh framework generation with a molecular dynamics (MD) method that allows us to generate dozens of topological configurations of the contact region of different objects. Energetically favorable junctions of carbon nanostructures, including Y- and X-shaped junctions of carbon nanotubes, a fullerene-nanotube junction, and a fullerene-graphene hybrid system are created using the developed original method.

© 2020 Elsevier B.V. Single phase barium titanate–bismuth ferrite ((1-x)BaTiO3-(x)BiFeO3, BTO-BFO) solid solutions were prepared using citric acid and ethylene glycol assisted sol-gel synthesis method. Depending on the dopant content the samples are characterized by tetragonal, tetragonal-pseudocubic, pseudocubic and rhombohedral structure as confirmed by Raman spectroscopy and XRD measurements. An increase of the BFO content leads to a reduction in the cell parameters accompanied by a decrease in polar distortion of the unit cell wherein an average particle size increases from 60 up to 350 nm. Non zero piezoresponse was observed in the compounds with pseudocubic structure while no polar distortion was detected in their crystal structure using X-ray diffraction method. The origin of the observed non-negligible piezoresponse was discussed assuming a coexistence of nanoscale polar and non-polar phases attributed to the solid solutions with high BFO content. A coexistence of the nanoscale regions having polar and non-polar character is considered as a key factor to increase macroscopic piezoresponse in the related compounds due to increased mobility of the domain walls and phase boundaries.

© 2020 Elsevier Ltd In Pt/Co/Ir/Co/Pt synthetic ferrimagnet, non-monotonic magnetic relaxation (NMMR) caused by switching of external magnetic dependends on Co layer thicknesse and temperature. In this paper, we have varied thickness of one of the Co layers in the Pt/Co/Ir/Co/Pt synthetic ferrimagnet in the 0.6–1.0 nm range at fixed Co layer thickness of another layer 1.1 nm in the 50–300 K range to find experimental conditions for NMMR. We found interdependence between Co layer thickness tCo and temperature T providing NMMR. Energy balance between magnetic anisotropies and exchange interaction of the two Co layers stipulates linear dependence of nessecary T on tCo. Exsact expression limitating magnetic anisotropies of the thick and thin Co layers and predicting NMMR conditions in tCo - T space is proposed. Altough all mentioned results relates to experiments in permanent magnetic field, the contribution of the NMMR to the magnetic hysteresis loops recorded in sweeping magetic field was experimentally found. Obtained results can be used for wide family of synthetic ferrimagnets with perpendicular anisotropy.

© 2020 Elsevier B.V. The chemical and biochemical analysis of bodily fluids after death is an important thanatochemical approach to assess the cause and time since death. Vitreous humor (VH) has been used as a biofluid for forensic purposes since the 1960s. Due to its established relevance in toxicology, a literature review highlighting the use of VH with an emphasis on endogenous compounds has not yet been undertaken. VH is a chemically complex aqueous solution of carbohydrates, proteins, electrolytes and other small molecules present in living organisms; this biofluid is useful tool for its isolated environment, preserved from bacterial contamination, decomposition, autolysis, and metabolic reactions. The post-mortem analysis of VH provides an important tool for the estimation of the post-mortem interval (PMI), which can be helpful in determining the cause of death. Consequently, the present review evaluates the recent chemical and biochemical advances with particular importance on the endogenous compounds present at the time of death and their modification over time, which are valuable for the PMI prediction and to identify the cause of death.

© 2020 Elsevier B.V. The chemical and biochemical analysis of bodily fluids after death is an important thanatochemical approach to assess the cause and time since death. Vitreous humor (VH) has been used as a biofluid for forensic purposes since the 1960s. Due to its established relevance in toxicology, a literature review highlighting the use of VH with an emphasis on endogenous compounds has not yet been undertaken. VH is a chemically complex aqueous solution of carbohydrates, proteins, electrolytes and other small molecules present in living organisms; this biofluid is useful tool for its isolated environment, preserved from bacterial contamination, decomposition, autolysis, and metabolic reactions. The post-mortem analysis of VH provides an important tool for the estimation of the post-mortem interval (PMI), which can be helpful in determining the cause of death. Consequently, the present review evaluates the recent chemical and biochemical advances with particular importance on the endogenous compounds present at the time of death and their modification over time, which are valuable for the PMI prediction and to identify the cause of death.

© 2020 Elsevier B.V. Herein four modified polymers were prepared from readily available addition poly(5-vinyl-2-norbornene) (PVNB) and their gas-transport properties were studied in detail. Hydrogenation, epoxidation, cyclopropanation and thiol-en reactions were chosen for the modifications of PVNB. Hydrogenation of PVNB was performed using p-toluenesulfonyl hydrazide. Epoxidation of PVNB was realized employing m-chloroperoxybenzoic acid. Cyclopropanation of PVNB was carried out using diazomethane in the presence of a Pd-catalyst. For thiol-en reaction, thioacetic acid was applied as the source of a thiol and AIBN as an initiator. All listed modifications were performed in high yields (≥80%) without the destruction of polymer main chains. The degree of functionalizations was up to 99%. The influence of these modifications on the properties of the resulting polymers was evaluated. Cyclopropanation and hydrogenation of PVNB led to an enhancement of gas permeability with minimal decrease in selectivity, while epoxidation or thioacetylation gave a substantial increase in CO2/N2 selectivity with decrease in permeability. The modified polymers with polar side-groups exhibited attractive selectivities for CO2/N2, CO2/CH4 and H2/N2 gas separations.