Components Of Strains Research Articles

Analysis of spectra of external impacts, reactions to them and limit states under the non-stationary modes of loading

It is noted that under real operating conditions of technical systems the so-called non-stationary loading in which external loadings increase or decrease arbitrarily is realized most often. At the same time final ratios between strains and stresses are of practical interest to engineering calculations. It is shown that for simple cyclic loadings the state equations in final ratios which are based on the theory of small elastic-plastic strains can be used. In this case the existence of the uniform generalized deformation diagram assuming a final relation between the corresponding components of stresses and strains both for initial and cyclic stages of deformation is essential for the analysis of considered conditions of a non-stationary cyclic loading. The analysis of conditions of achieving limit states at all stages of the life cycle the criteria base and the system of the computation equations become more complicated and more saturated by the factors taken into account and among them first external and internal impacts of natural, technogenic, anthropogenous origin, load from these impacts, and the reactions of installations to such impacts and loads as well. At the same time a set of criteria defining a limit state is presented in the form of a functional dependence characterizing a set of force and deformation parameters of the state of technical system on the one hand, and, on the other hand, a complex of criterion characteristics of constructional materials taking into account their change during operation. The most important step of determining conditions for achievement of the limit state causing fracture is establishing the critical parts that determine risks of emergency and catastrophic situations in which processes of local and main fractures are initiated. In this case transition of the operated installation from design area to the area of initiation of refusals, accidents and disasters occurs when the parameters of damage, defectiveness and risk reach their critical values.

Computationally-efficient locking-free isogeometric discretizations of geometrically nonlinear Kirchhoff–Love shells

Discretizations based on the Bubnov-Galerkin method and the isoparametric concept suffer from membrane locking when applied to Kirchhoff–Love shell formulations. Membrane locking causes not only smaller displacements than expected, but also large-amplitude spurious oscillations of the membrane forces. Continuous-assumed-strain (CAS) elements were originally introduced to remove membrane locking in quadratic NURBS-based discretizations of linear plane curved Kirchhoff rods (Casquero et al., CMAME, 2022). In this work, we propose CASs and CASns elements to overcome membrane locking in quadratic NURBS-based discretizations of geometrically nonlinear Kirchhoff–Love shells. CASs and CASns elements are interpolation-based assumed-strain locking treatments. The assumed strains have C0 continuity across element boundaries and different components of the membrane strains are interpolated at different interpolation points. CASs elements use the assumed strains to obtain both the physical strains and the virtual strains, which results in a global tangent matrix which is a symmetric matrix. CASns elements use the assumed strains to obtain only the physical strains, which results in a global tangent matrix which is a non-symmetric matrix. To the best of the authors’ knowledge, CASs and CASns elements are the first assumed-strain treatments to effectively overcome membrane locking in quadratic NURBS-based discretizations of geometrically nonlinear Kirchhoff–Love shells while satisfying the following important characteristics for computational efficiency: (1) No additional unknowns are added, (2) No additional systems of algebraic equations need to be solved, (3) The same elements are used to approximate the displacements and the assumed strains, (4) No additional matrix operations such as matrix inversions or matrix multiplications are needed to obtain the stiffness matrix, and (5) The nonzero pattern of the stiffness matrix is preserved. Analogously to the interpolation-based assumed-strain locking treatments for Lagrange polynomials that are widely used in commercial FEA software, the implementation of CASs and CASns elements only requires to modify the subroutine that computes the element residual vector and the element tangent matrix. The benchmark problems show that CASs and CASns elements, using either 2 × 2 or 3 × 3 Gauss–Legendre quadrature points per element, are effective locking treatments since these element types result in more accurate displacements for coarse meshes and excise the spurious oscillations of the membrane forces.

Low cycle fracture resistance of the superalloy at single- and two-frequency modes of loading

Fatigue and long static damages to the majority of high-loaded units develop under repeated stresses and strains of large amplitudes in elastic and elastoplastic regions at a low number of the main cycles and superimposition of dynamic stresses of significantly smaller value with higher frequencies which results in the so-called two-frequency modes of loading. It is shown that in the region of elevated and high temperatures, which determine the manifestation of temperature and time effects in the material, parameters of the rate and duration of deformation which enter the basic equation for determination of the fatigue life through the frequency and time of loading become the most significant parameters determining the fracture process. The results of theoretical and experimental study carried out on nickel superalloy specimens under a hard mode of loading and high temperatures have shown that estimation of the strength and fatigue life in this case for the single-frequency and two-frequency modes of loading can be performed on the basis of the analysis of strain parameters and diagrams of cyclic elastoplastic deformation using the deformation-kinetic criterion of summation of damages accumulated in the material. A decrease in the fatigue life under two-frequency mode of loading and the possibility of estimating it using the specified criterion and corresponding dependences with the introduction of the parameters of frequency/amplitude ratios of the strains (both full and that imposed on the main process) is experimentally proved. The calculated dependences include the parameters of temperature conditions, frequency and duration of loading which allows (when assessing damage from low-frequency and high-frequency components of cyclic strains) taking into account the effects of cyclicity and time of loading, as well as the existence of a variable coefficient of the asymmetry of high-frequency cycles of the two-frequency mode during high-temperature cyclic elastoplastic deformation.

Prediction of new likely emergent amino acid point mutations from USA, UK, Italy, France, Brazil, and India SARS-CoV-2 variants: a possible source for more reliable cocktail coronavirus vaccine

Abstract Objectives The interaction between genome components of the vaccines, host cells, and SARS-CoV-2 variants can cause mutation of amino acids at high random frequency. Hence, the present study is aimed at using the codon bases—amino acids components of some available strains with a view to determining new likely emergent strains of SARS-CoV-2. Methods Some genome sizes and lengths of SARS-CoV-2 variants were searched from literatures and other parameters were calculated. Point mutation of a single amino acid was deduced from 2/3 of sets of codon bases responsible for expression of amino acids. One base pair of 0.0047 nm Codon Base Table was used to deduce the likely missense amino acids at probability of one-twentieth. Key findings New generated codon bases gave rise to new emergent strains of varying numbers of amino acid pairs. Amino acids have reappeared and disappeared in some strains. Nine strains altogether have shown stop codon bases and the remaining strains have a tendency to form stop codons. Adenine has the highest frequency of the stop codon bases whereas cytosine is not among stop codons. A total of 906 new variants were deduced from 54 coronavirus strains which initially lacked stop codons. The newly predicted strains may become less pathogenic and could serve as immunogens via glycosylation. Strains with a higher number of codon bases undergo mutation faster and may end up in stop codons. Conclusion Hence the likely emergent strains could be less virulent, less pathogenic, and may fom glycans that could serve as a source for manufacturing of more reliable coronavirus vaccines.

Lactobacillus strains reduce the toxic effects of a subchronic exposure to arsenite through drinking water

The aim of the present study was to determine the efficacy of LAB strains in reducing the intestinal toxicity of arsenite [As(III)] and its tissue accumulation. For this purpose, Balb/c mice were randomly separated in four groups. One group received no treatment (control), one group received only As(III) (30 mg/L) via drinking water and the remaining two groups received As(III) via water and a daily dose of two LAB strains (Lactobacillus intestinalis LE1 and Lacticaseibacillus paracasei BL23) by gavage during 2 months.The results show that both strains reduce the pro-inflammatory and pro-oxidant response observed at the colonic level, partially restore the expression of the intercellular junction proteins (CLDN3 and OCLN) responsible for the maintenance of epithelial integrity, and increase the synthesis of the major mucin of the colonic mucus layer (MUC2), compared to animals treated with As(III) alone. Microbial metabolism of short-chain fatty acids also undergoes a recovery and the levels of fatty acids in the lumen reach values similar to those of untreated animals. All these positive effects imply the restoration of mucosal permeability, and a reduction of the marker of endotoxemia LPS binding protein (LBP). Treatment with the bacteria also has a direct impact on intestinal absorption, reducing the accumulation of As in the internal organs.The data suggest that the protective effect may be due to a reduced internalization of As(III) in intestinal tissues and to a possible antioxidant and anti-inflammatory activity of the bacteria through activation of pathways such as Nrf2 and IL-10. In vitro tests show that the protection may be the result of the combined action of structural and metabolic components of the LAB strains.

Sulfachloropyridazine (SCP) effects on anaerobic microorganisms and its degradation pathways

Sulfachloropyridazine (SCP) is frequently detected in animal excreta, as SCP commonly used in livestock and poultry for disease prevention. Anaerobic digestion (AD) has attracted much attention due to its ability to degrade antibiotics in animal excreta and convert animal excreta into renewable energy (biogas). But the degradation pathways of SCP in AD microorganism growth and SCP effect on the growth of AD microorganism are still unclear. In this study, the impact of SCP at 100 mg/L on the growth of representative AD microorganisms and the degradation pathways of SCP during single microorganism growth process were investigated using a pure culture method. Results showed that SCP has no effect on the growth of Clostridium tyrobutyricum and Methanosarcina barkeri, a positive effect on Peptoniphilus stercorisuis, but an inhibitory effect on Terrisporobacter glycolicus, Bacteroides caccae, and Proteiniphilum saccharofermentans, based on changes of cell growth (OD600), cumulative gas production, and gas components of strains. Meanwhile, SCP was degraded in varying degrees during the whole growth cycles of P. saccharofermentans, T. glycolicus, C. tyrobutyricum, B. caccae, P. stercorisuis, and M. barkeri, with degradation rates of 80.9%, 43.5%, 56.7%, 70.8%, 51.0%, and 21.4%, respectively. The SCP degradation pathway is different for these different strains, but the common degradation pathways were hydroxylation, C–N bond cleavage, release SO2, and nitration. These results revealed that anaerobic microorganisms have the high capability of degrading antibiotics and revealing degradation pathway is important for improving antibiotic degradation in AD process.

Study of the laminas’ stress-strain state for cross-ply composites with the [± 45°]2s lay-up: tensile tests

In this paper we have analysed the relations that allows one to determine the components of strains and stresses in the orthotropic axes of layered fiber reinforced composite materials in tensile and compression experiments for test specimens with the [±45°]2s lay-up. In particular, such relations were compiled on the assumption that in a cross-ply fiber composite two adjacent layers with the [±φ] lay-ups can be considered as one symmetrically reinforced layer with orthotropic properties. To establish the degree of accuracy of these relationships and assumptions, numerical experiments were carried out to determine the parameters of the stress-strain state of specimens consisting of two and four monolayers of a unidirectional fibrous composite material with the [±45°]2s lay-up. The analysis has been performed in the ANSYS finite element analysis program system in a linear formulation of two- and three-dimensional problems. It is shown that in the central zone of the specimen, the theoretical-experimental methodology based on the above mentioned relations has a sufficient degree of accuracy. Based on the analysis of results of three-dimensional problems, the formation of a linear torque in the specimen, which causes the twisting of some zones of the specimen along its length, has been revealed.

Retrospective immunogenicity analysis of seasonal flu H3N2 vaccines recommended in the past ten years using immunized animal sera.

Influenza A (H3N2) virus (A/H3N2) has complex antigenic evolution, resulting in frequent vaccine strain updates. We aimed to evaluate the protective effect of the vaccine strains on the circulating strains from past ten years and provide a basis for finding a broader and more efficient A/H3N2 vaccine strain. Eighty-four representative circulating A/H3N2 strains were selected from 65,791 deposited sequences in 2011-2020 and pseudotyped viruses were constructed with the VSV vector. We immunized guinea pigs with DNA vaccine containing the A/H3N2 components of the vaccine strains from 2011 to 2021 and tested neutralizing antibody against the pseudotyped viruses. We used a hierarchical clustering method to classify the eighty-four representative strains into different antigenic clusters. We also immunized animals with monovalent vaccine stock of the vaccine strains for the 2020-2021 and 2021-2022 seasons and tested neutralizing antibody against the pseudotyped viruses. The vaccine strains PE/09, VI/11 and TE/12 induced higher levels of neutralizing antibody against representative strains circulating in recommended year and the year immediately prior whereas vaccine strains HK/14, HK/19 and CA/20 induced poor neutralization against all representative strains. The representative strains were divided into five antigenic clusters (AgV), which were not identical to gene clades. The AgV5 strains were most difficult to be protected among the five clusters. Compared with single-dose immunization, three doses of monovalent vaccine stock (HK/19 or CA/20) could induce stronger and broader neutralizing antibodies against strains in each of the antigenic clusters. The protective effect of vaccine strains indicated that the accurate selection of A/H3N2 vaccine strains must remain a top priority. By increasing the frequency of immunization, stronger and broader neutralizing antibodies against strains in all antigenic clusters were induced, which provides direction for a new immunization strategy. This work was supported by a grant from National Key R&D Program of China (No. 2021YFC2301700).

EVALUASI POTENSI HASIL GALUR PADI LOKAL ACEH HASIL MUTASI RADIASI YANG TERINFEKSI BAKTERI Xanthomonas oryzae pv oryzae (Xoo) PENYEBAB PENYAKIT HAWAR DAUN BAKTERI

Bacterial leaf blight caused by Xanthomonas oryzaepv. oryzae is a biotic stress that can reduce rice productivity. This study aimed to influence the effect of Xanthomonas oryzaepv. oryzae on yield and yield components of several strains of radiation mutated of Aceh's local rice. This study used a non-factorial randomized block design with 3 replications. The factors being tested are 18 strains seeds of the radiation mutated of Aceh's local rice. The results showed that Line 118-(Snbr-238-112-118-180-11) infected with Xanthomonas oryzaepvoryzae (Xoo) had the highest yield potential of 12.43 tons ha. -1. There was no effect of Xanthomonas oryzaepvoryzaebacterial infection on the yield components except for the number of tillers. The strains that showed moderate resistance to Xoo were Sisambay (USK-Snbr-M04-238-081-002), Sanberasi (USK-Snbr-M04-238-017-023), Siteluk (USK-Snbr -M04-238-092-097, Sulutan Unsrat-1, Sibabus (USK-Snbr-M04-238-110-116), Simuara (USK-Snbr-M04-238-091-097B), Sikuala (USK-Snbr - M04-238-114-120), IRBB, 118-(Snbr-238-112-118-180-11), 119- (Snbr-238-112-119-160-10), while the Simeulu strain (USK-Snbr -M04-238-074-001), Sibahak (USK-Snbr-M04-238-073-079), Siluan (USK-Snbr-M04-238-058-064), UF5, Sibuluh (USK-Snbr-M04- 238-V1B-017), Sialavan (USK-Snbr-M04-238-051-057E), Snb, and UF 1 showed a slightly susceptible reaction. Keywords : rice, leaf blight, yield potential

Strength and Service Life of a Steam Turbine Stop and Control Valve Body

The stability of operation of steam turbines depends (along with other factors) on the reliable operation of their steam distribution systems, which are based on stop and control valves. This paper considers the strength of the elements of the K-325-23.5 steam turbine valves, in whose bodies, after 30 thousand hours of operation, cracks came to be observed. Previously determined were the nature of gas-dynamic processes in the flow paths of the valves and the temperature state of the valve body in the main stationary modes of operation. To do this, a combined problem of steam flow and thermal conductivity in stop and control valves was solved in a three-dimensional formulation by the finite element method. Different positions of the valve elements were considered taking into account the filter sieve. The assessment of the thermal stress state of the valve body showed that the maximum stresses in different operating modes do not exceed the yield strength. Therefore, the assessment of the creep of the valve body material is important to determine the valve body damage and service life. Modeling the creep of the stop and control valves of the turbine was performed on the basis of three-dimensional models, using the theory of hardening, with the components of unstable and steady creep strains taken into account. The creep was determined at the maximum power of the turbine for all the stationary operating modes. The maximum calculated values of creep strains are concentrated in the valve body branch pipes before the control valves and in the steam inlet chamber, where in practice fatigue defects are observed. However, even for 300 thousand hours of operation of the turbine (with a conditional maximum power) in stationary modes, creep strains do not exceed admissible values. The damage and service life of the valve bodies were assessed by two methods developed at A. Pidhornyi Institute of Mechanical Engineering Problems of the NAS of Ukraine (2011), and I. Polzunov Scientific and Design Association on Research and Design of Power Equipment. (NPO CKTI) – 1986. The results of assessing the damage and the turbine valve body wear from the effects of cyclic loading and creep of the turbine in stationary modes for 40, 200 and 300 thousand hours show that the thermal conditions of the body in the steam inlet chamber are not violated (without taking into account possible body defects after manufacture). The damage in valve body branch pipes after 300 thousand hours of operation exceeds the admissible value, with account taken of the safety margin. At the same time, the damage from creep in stationary operating modes is about 70% of the total damage. The maximum values of damage are observed in the areas of the body where there are defects during the operation of the turbine steam distribution system. The difference between the results of both methods in relation to their average value is ~20%.

Extending the formulation of the spatial autocorrelation (SPAC) method to strain, rotation and tilt

SUMMARYThe spatial autocorrelation (SPAC) method has been applied to ambient seismic noise measured by arrays of translational seismometers for inverting phase-velocity dispersion curves of Rayleigh or Love waves for shallow S-wave velocity structure. Recently, it is becoming possible to observe wave spatial gradients such as strain, rotation and tilt owing to the development of dense seismic networks and improving measurement technologies. Therefore, it is desirable to extend the formulation of the SPAC method to strain, rotation and tilt. This study presents analytical expressions of cross-spectra and coherence of the strain, rotation and tilt components that are measured on the free surface. According to the results, both Rayleigh and Love waves contribute to most components of strains. The exceptions are the areal strain and the vertical axial strain (ezz) on the free surface that are affected by only Rayleigh waves. Only Rayleigh waves contribute to the tilts and rotations around the horizontal axes on the free surface, too. On the other hand, only Love waves contribute to the rotation around the vertical axis. Therefore, different kinds of wave spatial gradients are helpful to separate Rayleigh and Love waves correctly. For practical applications, the analytical expression for the radial axial strain (err) component will be applied directly to distributed acoustic sensing data measured with straight sections of a fibre-optic cable. On the other hand, dense observations of rotation and tilt may still be difficult to carry out at present. However, an application of analytical formulations in this study to arrays of at least several three-component rotational seismometers is attractive because it enables us to separately estimate the phase velocities of Rayleigh and Love waves.

Theoretical and numerical study for unsteady tube expansion using hemispherical dies

Unsteady hemispherical die expansion process was investigated theoretically and numerically, using a 48 mm base diameter die. Brass specimens of 32 mm inner diameter, and 1.5, 2, and 3 mm initial wall thickness were simulated using Coulomb’s friction concept with a coefficient of 0.1. The governing equation was derived, and solved for the perfect plastic condition. Reasonable agreement was found between the theoretical and the finite-element results for the relation between forming stress vs. expansion ratio which was noticed to be less affected by the wall thickness. The wall plastic bending at the die entrance was developed to wall curling and waving for all cases. The three components of strains were also studied using the finite-element method. It was noticed that the circumferential strain is always tensile, whilst the radial strain is compressive at the expanded end but turns to tensile at the die entrance. The complexity of expansion process was reflected clearly through the longitudinal strain distribution, it begins as a compressive strain at the expanded end with increasing compressive strain until it reaches its maximum compressive value at a distance about 5 mm from the expanded end, then vanishes at the die entrance.

Bimoment theory construction to assess the stress state of thick orthotropic plates

The paper is devoted to the development of a theory and method for calculating thick plates. A detailed analysis of well-known publications devoted to this problem is given. A theory and a method were developed to assess the stress-strain state of thick plates without simplifying hypotheses within the framework of three-dimensional theory of elasticity. When constructing a theory, all components of strains and stresses arising from the nonlinearity of the law of displacement distribution along the plate thickness were taken into account. The equations of motion of the plate were constructed with respect to forces, moments and bimoments. The solution method was based on exact expressions in trigonometric functions. The bending of isotropic and orthotropic plates was considered as a calculation example. The solution obtained showed the effectiveness and accuracy of the proposed bimoment theory in assessing the stress-strain state of thick plates.

Количественная характеристика полей локальных деформаций в образце картона топлайнер при одноосном растяжении

The paper presents the method for quantifying the distribution of local tensile (longitudinal), compressive (transverse) and shear strains in a sample of pulp and paper material. The results of its use for the sample of top-liner board when uniaxial tensile testing are provided. Applying this method, we have determined the values, the degree of heterogeneity and change patterns of local strains in inhomogeneous and anisotropic structure of the sample, depending on the total strain and the direction of fiber orientation. The method is based on constant-speed tensile testing of samples with a pre-applied dot matrix to their surface. The test is accompanied with photo fixing and recording a load-elongation curve. The coordinates and displacements of dots are determined by means of the specially designed software. The analysis of data and calculation of local deformations are performed by finite elements method (FEM) algorithms. The outcomes have shown that the local longitudinal deformations increased, transverse – decreased, and shear – had their maximum at 45° to machine direction (MD) when increasing the angle of preferential fiber orientation to MD in the board samples. The rise of the average absolute values of all components of local strains when increasing total deformation in the sample was confirmed. As it has been found, the heterogeneity of local strains, estimated through the standard deviation, rose when increasing their absolute value; the trends of changing depend on the fiber orientation direction in the sample structure. For citation: Romanova A.N., Kazakov Ya.V., Malkov A.V. Quantitative Characteristics of Local Strain Fields in a Top-Liner Board Sample under Uniaxial Tension. Lesnoy Zhurnal[Russian Forestry Journal], 2020, no. 1, pp. 180–189. DOI: 10.37482/0536-1036-2020-1-180-189

Neutron strain scanning for experimental validation of the artificial intelligence based eigenstrain contour method

The demand for energy generation with low carbon emissions evoked the development of ultra-super critical technology that allows operating steam turbines at high temperature and pressure conditions. However, operating at extreme conditions necessitates careful consideration of structural integrity which is affected by residual stresses. Welding is used for joining of components of steam turbines, but this process causes the formation of residual stresses of complex form. Careful investigation is necessary to understand the distribution of potentially detrimental residual stress fields. Eigenstrain theory was previously used for the development of the artificial intelligence based eigenstrain (AI-eig) contour method that allowed advanced modelling of the behaviour of Inconel alloy 740H under thermo-mechanical loading conditions. Models created using this method are capable of evaluating the residual stress fields in the whole specimen or in the parts and slices created using electric discharge machining (EDM). In the previous applications of the AI-eig contour method, the determination of the distribution of eigenstrain in as-welded and heat-treated specimens was followed by the calculation of volumetric residual stresses. In this study, long- and short-transverse components of the residual strains determined by the AI-eig contour method applied to EDM-cut surfaces of the parts of as-welded and heat-treated specimens were validated using the neutron strain scanning method. The results demonstrate the effectiveness of the integrative modelling approach that enables the determination of eigenstrains in the whole specimen and the calculation of residual strains before and after the machining process.

Ползучесть и длительная прочность металлов при нестационарных сложных напряженных состояниях (обзор)

Данная статья представляет собой аналитический обзор экспериментальных и теоретических исследований ползучести и длительной прочности металлов при нестационарных сложных напряженных состояниях, опубликованных за последние 60 лет. Первые систематические исследования ползучести металлов при сложном напряженном состоянии были опубликованы в конце 50-х и начале 60-х годов ХХ века в Советском Союзе (Л. М. Качанов и Ю. Н. Работнов) и Великобритании (A. E. Johnson). Пионерские работы по длительной прочности впервые появились в СССР (Л. М. Качанов и Ю. Н. Работнов). Впоследствии Ю. Н. Работнов разработал кинетическую теорию ползучести и длительной прочности, с помощью которой можно эффективно описывать различные особенности процесса ползучести металлов вплоть до разрушения при различных программах нагружения. В разных вариантах кинетической теории используются либо скалярный параметр поврежденности, либо векторный параметр, либо тензорный параметр, либо их комбинация. Вслед за работами М. Качанова и Ю. Н. Работнова механика континуального разрушения стала развиваться в Европе, в Азии и затем в США. В качестве основной связи компонент тензоров напряжений и деформаций ползучести принимается гипотеза пропорциональности девиаторов напряжений и девиаторов скоростей деформаций ползучести. При моделировании экспериментальных данных коэффициент пропорциональности в этой зависимости принимает разные формы. Основная проблема в развитии данного направления состоит в трудностях получения экспериментальных данных при произвольных программах нагружения. В данном обзоре приведены основные результаты исследований, проводимых учеными разных стран. Кроме Ю. Н. Работнова и Л. М. Качанова, существенный вклад в развитие рассматриваемого направления науки внесли также российские ученые Н. Н. Малинин, А. А. Ильюшин, В. С. Наместников, С. А. Шестериков, А. М. Локощенко, О. В. Соснин, Ю. П. Самарин, А. Ф. Никитенко и др.

Metabiotics: prospects, challenges and opportunities

In this review authors discuss modern condition of treatment and prophylaxis of human metabolic diseases associated with microecological imbalance of intestinal symbiotic microbiota. Now the most frequently for these aims various probiotic nutrient additives and functional fermented foods prepared on the basis of living bacteria have been used. Unfortunately such probiotics have not possessed the real effectiveness and are not completely safe. Instead of traditional commercially available living probiotics the authors suggest to use novel microecological means (metabiotics) that are structural components of probiotic bactrerial strains, and/or their metabolites and/or signaling molecules with known chemical structure. Metabiotics can optimize host‑specific physiological, regulator, metabolic and/or hormone/behavior functions and reactions. Metabiotics possess some advantages in future personalized medicine because they have exact chemical structure, well dosed, safe and long shelf‑life.

Modeling of the Elastoplastic Deformation of a Body Based on the Energy Balance and Monitoring of Strains

We analyze some aspects of adequate determination of the energy state of the surfaces of structural elements according to the results of monitoring of strain fields in the complex stressed state. The importance of application of the notions of strain and stress intensity is indicated. We establish the dependence of errors caused by neglecting all components of strains both in the elastic and plastic zones on the mechanical properties of the material and the stiffness of deformation.

Exact model for the response of moderately thick laminates to transverse forces

Under the premise of homogeneous force, or curvature-gradient, distribution, a solution for transverse-shear strains and stresses, warping functions, and through-thickness displacements is derived by satisfying all relations and conditions of linear elasticity. Only for calculating the substitute-plate transverse-stiffness matrix the principle of the minimum of the total potential energy is used as a scheme for correctly combining energetically conjugate components of stresses and strains for the entries of the substitute-plate transverse stiffness matrix. The model is valid for all laminate and sandwich designs. The said premise renders the model a point theory rather than a structural theory, so that it is a complement to the classical theory of laminated plates in the sense of mapping substitute-plate properties and distribution of state variables through the laminate thickness. This paper explains the modeling ideas and derivations in detail. Predictions of the responses for a set of sample laminates of varying complexity, and comparison of stiffness values with those obtained by a dedicated FEM formulation, verify the model.

Robust four-node elements based on Hu\u2013Washizu principle for nonlinear analysis of Cosserat shells

Mixed 4-node shell elements with the drilling rotation and Cosserat-type strain measures based on the three-field Hu–Washizu principle are proposed. In the formulation, apart from displacement and rotation fields, both strain and stress resultant fields are treated as independent. The elements are derived in the framework of a general nonlinear 6-parameter shell theory dedicated to the analysis of multifold irregular shells. The novelty of the developed elements stems from the fact that the measures of assumed strains and stress resultants are asymmetric. The original interpolation of drilling and bending components of strains and stress resultants is proposed. In the formulation of new mixed elements, two variants of the interpolation of membrane components are used and interpolation of the independent fields is defined in the natural or skew coordinates. Accuracy and efficiency of the developed elements are tested in several linear and nonlinear numerical examples. It is shown that smaller number of independent parameters in the interpolation of membrane components gives more accurate results. The proposed mixed 4-node elements enable the use of large load steps in nonlinear computations. Moreover, they require significantly less equilibrium iterations than other shell elements formulated in the 6-parameter shell theory.