We report on the unified approach to the classification of defects in continuum-based analysis of the defect self-distortions. Defects of various dimensionality including point, linear, surface, and ...volume defects are considered depending on the domain of self-distortion definition. The results of analytical calculations of elastic fields and the energies of dislocations, disclinations, and inclusions in bodies of various geometries with internal and external boundaries are considered. Examples of defects in modern functional materials, e.g., graphene, are given. It is discussed how the presence of defects and associated elastic fields affects the properties of modern functional materials and the characteristics of devices based on them.
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DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
High refractive glasses in the La2O3–Nb2O5–B2O3 (LNB) system were synthesized by the melt-quenching technique and correlations between their compositions and structural features were clarified. It ...was found that the refraction index of the LNB glasses is tunable from 1.71 to 1.98 by the variation of the Nb2O5 fraction from 5 to 30 mol%. The infrared spectroscopy analysis implies on the presence of three and four coordinated borate units, as well as six coordinated niobium atoms. The X-ray absorption (La L3-edge and Nb K-edge XANES and EXAFS) spectroscopy and total X-ray scattering results show that niobium atoms maintain octahedral oxygen coordination despite the wide variation of the Nb2O5 content, while average lanthanum coordination number is versatile and changes from ~8 to ~10. The interatomic distance values testify that the niobium octahedra in the glass network are connected only “by corners”. The stability of niobium local atomic structure implies that the main source of the changes in the optical properties of studied glasses is the variation of the Nb2O5 content. The deeper understanding of the local atomic structure of the high refractive index LNB glasses paves ways for the development of new glass wafers for cutting-edge augmented reality devices.
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•High refractive index Nb2O5–La2O3–B2O3 glasses derived by the melt-quenched technique.•Local atomic structure of Nb and La studied by the X-ray synchrotron techniques.•Nb atomic structure weakly depends on the concentration of Nb2O5.•Nb octahedra connected “by corners” in the glass network.•Local atomic structure of La is sensitive to the concentration of Nb2O5.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
We develop a new technique for finding elastic fields for axisymmetric dilatational inclusions (DIs) in the forms of finite cylinder and truncated sphere, when the DIs and surrounding infinite matrix ...have the same isotropic elastic moduli. DIs are built of circular dilatational disks distributed continuously along the axis of symmetry. Total displacements of DIs are found by integration of the displacements of a dilatational disk. Then, using the linear elasticity equations, the elastic fields of cylindrical and truncated spherical DIs are derived and written via compact easy-to-read and easy-to-calculate Lipschitz-Hankel integrals and Lur'e series, correspondingly. The independence of the strain energy and the elastic dilatation on the DI shape is confirmed. The effect of the aspect ratio and the shape on the elastic fields of the DIs is analyzed. The elastic model of Janus particle and other possible useful applications of solved problems are discussed.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Disclinations together with dislocations represent a class of linear defects in solids. Disclinations are characterized by typical singularities and the property of multi-value of the fields of ...displacement and rotation associated with the defects. We present an introduction to and overview of recent achievements of the disclination approach in physics and mechanics of solid structures. In the development of F.R.N. Nabarro ideas, the use of the disclination approach in materials science is demonstrated. The following milestones of the disclination concept are given and discussed: (i) definitions and designations for Volterra dislocations, Frank (rotation) vector of a disclination, wedge and twist disclinations; (ii) geometry of disclinations in structure-less and crystalline solids; (iii) the properties of screened low-energy disclination configurations, e.g. loops, dipoles, defects at the vicinity of a free surface, including the methods and results of calculation of their elastic fields and energies. Then using the properties of screened disclinations a number of qualitative and quantitative models for the structure formation and evolution in plastically deformed materials, is considered. Disclination theory of grain boundaries and their junctions in conventional polycrystals is presented. The bands with misorientated crystal lattice in metals and other materials are described as a result of partial wedge disclination dipole motion. Disclination approach is applied to the study of work-hardening at large strains. For nanocrystals, disclination approach allows to explain the peculiarities of the flow stress dependence on the grain size. The contribution of disclinations to relaxation of mechanical stresses in lattice mismatched thin layers placed on the bulk substrate is examined and linked to the appearance of domain patterns. Finally, disclination models for the structure and properties of nanoparticles are presented. These models treat the pentagonal symmetry of micro- and nanoparticles and nanorods of materials with FCC crystal structure and explain stability and relaxation phenomena in such pentagonal objects.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
We studied the effect of bone marrow autotransplantation on the morphofunctional properties and numerical population of mast cells. The experiments were performed on 4-monthold male mice. The animals ...received an injection of a suspension of bone marrow obtained from the femoral epiphyses of these animals into the caudal vein. In 40 min and 2 h after autotransplantation, the number of tryptase-positive mast cells increased by 1.1 times. The formation of groups of mast cells near erythroid-neutrophil islets and near blood vessels was observed. The proportion of metachromatic mast cells significantly increased. By the degree of mast cells degranulation, we detected non-degranulated up to 48.0±1.4% (
vs
55.2±1.2% in intact mice) and moderately degranulated mast cells 22.0±1.2% (
vs
18.2±0.9% in intact mice); the percentage of actively degranulated cells was 10.0±0.8% (
vs
3.6±0.9% in intact mice;
p
<0.05). Morphometric parameters of mast cells were changed, with a slight increase in their diameter and distance between the cells. The number of histamine-containing mast cells increased significantly (by 3.2 times in 40 min and by 5.9 times in 2 h) and histamine content in these cells also increased. Thus, bone marrow autotransplantation led to intensification of degranulation and sulfation of mast cells and the release of histamine from them.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
The histamine content in bioamine-containing cells and the content of NSE
+
cells of the lymph nodes were studied in rats in 40 min and in 2 and 4 h after bone marrow allotransplantation by using the ...cross luminescence-histochemical method and immunohistochemical method, respectively. Within 2 h after allotransplantation of the bone marrow, a significant increase in histamine content in bioamine-containing cells and an increase in the number of NSE
+
cells in the period were observed. Both APUD and NSE+ cells were found to be heterogeneous by staining and luminescence.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
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•Dilatational conical inclusion (CI) is modelled as the set of dilatational infinitesimally thin disks with linearly varying diameter along the cone symmetry axis.•Analytical ...expressions are presented for total displacements, elastic strains, and stresses of the CI in spherical coordinates with the origin in the cone-apex in the form of the series with Legendre polynomials.•The specific features of an “hourglass” dipole inclusion consisting of two CIs with opposite sign of their eigenstrains are demonstrated.
In this article, the analytical solution for the isotropic elasticity problem for the cone-shaped inclusion with dilatational eigenstrain in an infinite medium is given. The conical inclusion is modeled by dilatational infinitesimally thin circular disks distributed continuously along the cone z-axis with the radii of the disks being proportional to z-coordinate. The displacements, strains, and stresses of the conical inclusion are given in spherical coordinates with the origin in the cone-apex in the form of the series with Legendre polynomials. The maps of the displacements and the stresses are presented. A comparison of the displacements of the conical inclusion with the displacements of the finite cylindrical and hemispherical inclusions is provided. It is also shown, as expected, that the energy of the dilatational inclusion does not depend on its shape. In Discussion section, the specific features of an “hourglass” dipole inclusion consisting of two conical inclusions with different sign eigenstrains are demonstrated.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
A theoretical model is suggested to determine the critical conditions for generation of circular prismatic misfit dislocation loops in hollow core–shell nanoparticles. Based on a strict solution of ...the linear elasticity boundary-value problem for a circular prismatic dislocation loop in a free-surface shell, we examine the loop formation energy in the nanoparticle and show a potential opportunity to fabricate hollow, coherently bonded, i.e. dislocation-free, core–shell nanoparticles by using thin-wall shells with inner-to-outer radii ratio >0.8 as supporting cores.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
The sources of internal stresses in nanowires are considered, the model of which is an infinite elastically isotropic cylinder of circular cross section. Sources of internal stresses are defects that ...have their own distortion (eigenstrain) and are localized either at a point, on a line, on the surface, or in a region inside the nanowire. Relations are given for the elastic fields and energies of some defects in nanowires, including rectilinear (straight) dislocations and disclinations, dislocation loops, and dilatation inclusions. The interaction between sources of internal stresses in an elastic cylinder is analyzed. The role of the found solutions to the problems of solid mechanics in the interpretation of relaxation processes in pentagonal nanowires and hybrid semiconductor nanostructures with radial and axial heterointerfaces is discussed.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Exploring an approach to grain boundary (GB) mesoscopic structure in 3D polycrystals, we develop a model description for equilibrium and non-equilibrium states of GBs in graphene. Non-equilibrium ...states of GBs in graphene are analyzed for the first time. On the base of this model, dependence of total energy for symmetric GBs on the misorientation angle, E(θ), in graphene was calculated. It was found that for the same average misorientation angle the energy in a non-equilibrium state of a GB in graphene can significantly exceed the energy in the equilibrium state. In graphene, the GB energy depends to a greater extent on the deviation from the equilibrium state than on the misorientation angle. It is proposed to account for the presence of non-equilibrium GBs in the explanations of unusual physical properties of graphene.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
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