Response evolution of a tetrachiral metamaterial unit cell under architectural transformations

This paper studies a mechanical metamaterial with tetrachiral topology by mathematical modeling. Chirality is the property of an object that makes the object distinguishable from its mirror image; chirality can be left‐ or right‐handed. The mechanical response of two metamaterial unit cells with different configurations (patterns A and B) is investigated. It is found that the cubic cell with a regular pattern A exhibits orthotropic mechanical behavior under loading along three coordinate axes. An irregular pattern B differs from pattern A in that the upper face of the unit cell has an opposite chirality. This architectural transformation is considered as a topological defect, which enhances the twisting effect in the loaded metamaterial. Analysis of displacements and stresses shows that the mechanical behavior of the pattern B cell is described by the model of a transversely isotropic material. The orthotropic and transversely isotropic behavior of the cells of given configurations is also confirmed by the values of the effective elastic constants. Microstructural geometry and mechanical deformation of metamaterials are shown to be closely related. It is shown that a topological defect in a unit cell of a tetrachiral metamaterial strongly determines its twisting behavior

High frequency polarization switching of a thin ferroelectric film

We consider both experimentally and analytically the transient oscillatory process that arises when a rapid change in voltage is applied to a $Ba_xSr_{1-x}TiO_3$ ferroelectric thin film deposited on an $Mg0$ substrate. High frequency ($\approx 10^{8} rad/s$) polarization oscillations are observed in the ferroelectric sample. These can be understood using a simple field-polarization model. In particular we obtain analytic expressions for the oscillation frequency and the decay time of the polarization fluctuation in terms of the material parameters. These estimations agree well with the experimental results

Structure and Peculiarities of a Clinical Course of Tick-Borne Infections in Children of the Irkutsk Region

At present there are few studies generalizing the clinical picture of infections, transmitted by Ixodid ticks, in children population. Tick-borne viral encephalitis is still one of the important natural focal infections and accounts for up to 27 % among other tick-borne infections.The aim of the study was to determine the structure and features of the clinical course of tick infections in children of the Irkutsk region.Materials and methods. We conducted a retrospective analysis of 58 cases over three-year period from 2015 to 2017 of children aged 1 to 18 years diagnosed with tick-borne viral encephalitis (TVE), ixodid tick-borne borreliosis (ITB), tick-borne rickettsiosis (TR) according to the data of Irkutsk Regional Infectious Clinical Hospital.Results and discussion. Among tick-borne infections, TVE was found in 43 % of cases, ITB – in 27.5 %, TR – in 29.5 %, there was one case of mixed infection: TVE + tick-borne typhus in North Asia. In TVE, feverish form was found in 40 % of cases, meningeal form – in 36 %, meningoencephalitic form – in 20 %, polyradiculonevritic form – in 4 %. Medium severity was observed in 56 % of cases, severe – in 28 %. In ITB, non-erythematous form was revealed in 62.5 % of cases, erythematous – in 12.5 %. Clinical and epidemiological TR was registered in 18 % of cases. In patients with TVE recovery was observed in 84 %, however, there were 4 % of neurological complications. With the diagnosis of ITB and TR, almost all children were discharged in a satisfactory condition. No deaths were reported within 3 years. According to the medical history: only 1 child was vaccinated against TVE, 2 children underwent seroprevention; ticks, who bit 4 patients, were studied. Medical history showed that 57 % of children had tick bites, and 7 % of cases associated the disease with consumption of non-boiled goat or cow milk. Residents of Irkutsk, Angarsk and Shelekhov comprised 47 %, residents of the Irkutsk region – 53 %. The most common localization of bites is the head and neck.Conclusion. There is a low public commitment to the vaccine prevention of tick-borne infections. Therefore, it is necessary to promote both specific and non-specific prevention of tick-borne encephalitis among children of the Irkutsk region

Sex differences of molecular mechanisms of insulin sensitivity in young and adult C57BL/6J mice

Reduced insulin sensitivity plays an important role in the pathogenesis of type II diabetes. There are sex differences in the development of metabolic disorders. The aim of this work was to investigate the insulin signal transduction gene expression in mice of different sex and age. Male and female C57BL/6J mice were used in our studies. Gene expression was assayed by RT-PCR. It was shown that insulin sensitivity in females was higher than in males regardless of age because the level of glucose in blood plasma of females does not differ from that in males, whereas female insulin levels were lower than male insulin levels. Female glucose tolerance increased with age, and glucose tolerance was higher in females than in males at the age of 30 weeks. It was shown that sex and age affect the expressions of insulin signal transduction genes. It was shown that there are sex differences in the levels of mRNA Pik3cd in the liver, in the levels of mRNA Irs1 in the muscle, in the levels of mRNA Irs1 and Slc2a4 in adipose tissue at the age of 10 weeks, and there are sex differences in the levels of mRNA Irs2 and Pik3cd in the liver, in the levels mRNA Pik3cd and Slc2a4 in the muscle, in the levels mRNA Insr and Pik3cd in adipose tissue at the age of 30 weeks. In young animals, the expression of the genes was higher in females than in males in all tissues. In adult animals, the expression of the genes in the liver was higher in females than in males, the expression of the genes in muscle and adipose tissues were lower in females than in males. In males, the levels of mRNA Insr in the liver and muscles and mRNA Pik3cd in adipose tissue decreased with age, and the level of mRNA Pik3cd in muscles  increased with age. In females, the levels of mRNA Irs1 in muscle and mRNA Pik3cd and Slc2a4 in adipose tissue decreased with age. Thus the molecular basis of sex differences and age-related changes in insulin sensitivity may be a change in expressions of insulin signal transduction genes in the target tissues

О формировании химического и изотопного состава подземных вод иренского горизонта (на примере Кунгурской ледяной пещеры)

Seasonal changes in the chemical and isotopic composition (deuterium and oxygen-18) of surface runoff water, atmospheric precipitation, infiltration and groundwater of the Kungur Ice Cave were studied. The study was conducted for the purpose of a comprehensive analysis of groundwater, determination of patterns of change, and relationship between the characteristics of different water types, that is necessary for a more effective assessment of groundwater resources and prediction of the composition and quality of groundwater. The movement of groundwater in the cave has a complex character. The main flow paths, periodicity and some peculiarities of water movement in the karst massif have been determined and confirmed. Obtained data are valuable for hydrochemical monitoring in the cave.Изучены сезонные изменения химического и изотопного состава (дейтерия и кислорода-18) вод поверхностного руслового стока, атмосферных осадков, инфильтрационных и подземных вод Кунгурской ледяной пещеры. Исследование проведено с целью комплексного анализа подземных вод, определения закономерностей изменения и зависимостей между составом разных видов вод, необходимого для более эффективной оценки ресурсов подземных вод и осуществления прогнозирования состава и качества подземных вод. Установлены и подтверждены основные пути, временной интервал и некоторые особенности перемещения вод в карстовом массиве. Эти данные имеют ценное значение при проведении гидрохимического мониторинга в пещер

STRUCTURE AND TRANSPORT PROPERTIES OF NIOBATES AND ERBATS OF BISMUTH

The solid solutions with general formula have been prepared by solid state synthesis. Analysis of the powder X-ray diffraction data has shown that the samples crystallize in cubic space group Fm3m. Microscopic research were performed using a REM. Electrical conductivity was studied by impedance spectroscopy. The electrical conductivity of doped samples exceeds the matrix value and increases with increasing concentration of dopant

Indicators of Pasture Digression in Steppe Ecosystems of Mongolia

The research shows that widely used key measures of vegetation structure (species diversity, projected cover and above-ground phytomass) are not always suitable as indicators of pasture degradation. Based on an analysis above-ground phytomass composition, new quantitative indices are offered that give a more realistic picture of rangeland condition in Mongolia

The association study of polymorphic variants of hypothalamic-pituitary-adrenal system genes (AVPR1B, OXTR) and aggressive behavior manifestation: a focus on social environment

Considering a multifactorial nature of developing aggression, the present study is aimed to estimate both the genetic- and haplotype-based effects of the OXTR and AVPR1B genes and gene-by-environment interactions in developing A

Peculiarities of structure and phase composition of V-Ti-Cr alloy obtained by sintering technique

Abstract Alloy of the V-Ti-Cr system is a promising material exploited under high radiation and in corrosion environment. We sintered V-4.9Ti-4.8Cr alloy from particles with original average size of 30, 280 and 200 μm, respectively for vanadium, titanium and chromium powders, by pressing of the powder mixture and its further sintering. The studies were undertaken using the methods of X-ray structural analysis, scanning electron microscopy with an energy dispersive analyzer and transmission electron microscopy. It was established that the structure of the alloy represented matrix grains (BCC solid solution), along the boundaries and at junctions of which the groups of oxycarbonitride particles of V, Ti, Cr (C,N,O) type of the variable elemental composition were arranged. The particles possessed a plate-like (0.4 x 2.0 μm) and rounded (0.5 μm) shape. The solid solution of the alloy was heterogeneous by concentration. This was evidenced by the complications of the diffraction patterns obtained from the corresponding sections of the structure. These were cords of main reflexes, satellites and emergence of a moire banded contrast in separate sections of the sample. Inside the matrix grains, there were nanoparticles (15 μm) of carbide V55Cr25C20, being a source of elastic internal local stresses

GENERATION OF BLOOD THROMBIN IN PATIENTS WITH CANCER OF PANCREATOBILIARY ZONE COMPLICATED WITH OBSTRUCTIVE JAUNDICE

Obstructive jaundice is one of the most frequent complications of cancer of pancreatobiliary zone that starts the developments of hemorrhagic complications. This group of patients has decrease of coagulation potential that is expressed in changes of process of thrombin generation even before the operative treatment. The article presents the results of the research of indices of process of thrombin generation by Calibrated. Automated. Thrombogram. method in 57 patients with cancer of pancreatobiliary zone complicated with obstructive jaundice before the operative treatment