Bone marrow mesenchymal stromal cells are multipotent and can differentiate into cells of various tissues, which determines their high importance for clinical application. We performed an
in vitro
...study of the osteogenic potential of mesenchymal stromal cells cultured on intact polylactide scaffolds or scaffolds modified with collagen I or fibrin. Scanning electron microscopy showed that the cells formed osteogenic nodules or osteogenic nodules on both intact and fibrin-modified polylactide scaffolds. Spectrophotometric detection of alkaline phosphatase activity on days 7 and 11 showed that mesenchymal stromal cell grown on intact polylactide scaffolds and on scaffolds modified with collagen type I or fibrin more intensively synthesized alkaline phosphatase than in the control (culture plastic). This dependence increases in the presence of osteogenic differentiation factors in the medium. After long-term culturing (4 weeks), the presence of calcium deposits detected by alizarin red staining confirmed the osteoinductive properties of intact and protein-modified polylactide scaffolds. These findings suggest that polylactide scaffolds and collagen I increase the osteogenic differentiation potential of mesenchymal stromal cells.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
In the article, the content of education law as an object of economic analysis is defined. The characteristics of education law as a complex body of law are identified.The specificity of the ...interpretation of the content and structure of the education-related legislation is analyzed.
Collagen I gels with protein concentrations of 1, 2, and 3.5 mg/ml were prepared and embedded in a porous polylactide scaffold to reduce their contraction. Concentration of the gel did not affect its ...degradation. Collagen gels promoted the formation of cell networks. The cells in the collagen gel with a concentration of 1 mg/ml embedded in polylactide scaffold had elongated spindle-like shape, in contrast to flattened cells in collagen gel of the same concentration not embedded in the scaffold. Stabilization of the collagen gel in the polylactide scaffold promoted active synthesis of laminin and fibronectin by cells as soon as on day 5 of culturing in comparison with that in free collagen substrate.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
The growth mechanism, microstructure, and crystal structure of the polycrystalline n-Bi2Te3 thin films with thicknesses d=15–350nm, prepared by thermal evaporation in vacuum onto glass substrates, ...were studied. Bismuth telluride with Te excess was used as the initial material for the thin film preparation. The thin film characterization was performed using X-ray diffraction, X-ray photoelectron spectroscopy, energy-dispersive X-ray spectroscopy, scan electron microscopy, and electron force microscopy. It was established that the chemical composition of the prepared films corresponded rather well to the starting material composition and the films did not contain any phases apart from Bi2Te3. It was shown that the grain size and the film roughness increased with increasing film thickness. The preferential growth direction changed from 00l to 015 under increasing d. The X-ray photoelectron spectroscopy studies showed that the thickness of the oxidized surface layer did not exceed 1.5–2.0nm and practically did not change in the process of aging at room temperature, which is in agreement with the results reported earlier for single crystals. The obtained data show that using simple and inexpensive method of thermal evaporation in vacuum and appropriate technological parameters, one can grow n-Bi2Te3 thin films of a sufficiently high quality.
•The polycrystalline n-Bi2Te3 thin films were grown thermal evaporation onto glass.•The growth mechanism and film structure were studied by different structure methods.•The grain size and film roughness increased with increasing film thickness.•The growth direction changes from 00l to 015 under film thickness increasing.•The oxidized layer thickness (1–2nm) did not change under aging at room temperature.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
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The effect of the Biosit-Sr Elkor glass-crystalline material on the early stages of morphogenesis of osteoid structures in cultures of mesenchymal stromal cells of bone marrow was studied. The ...maximum cultivation time was 28 days. Morphological investigations were performed with scanning electron microscopy. It was found that silicoaluminophosphate facilitated the generation of osteoid structures; enhanced the synthesis, compaction, and mineralization of fibrillar collagen; and activated matrix vesicles by hyperplasia, hypertrophy, and excretion. During cultivation, glass-crystalline material partially dissolved and disintegrated. Chemical substances with cross-linking, surface-active, and mineralizing properties came out into the nutrient medium. By means of surface-active agents, compacted collagen fibers were straightened and perforated, forming diversified lamellar structures, the precursors of bone plates. The mineralizing effect is mediated by increased homo- and heterogeneous nucleation of calcium phosphates and deposition of mineral concretions in differentiating cells and fibers of the collagen substrate, which accelerates the involution of cell culture. It was concluded that Biosit-Sr Elkor glass-crystalline material has a stimulating effect on the early stages of osteogenesis in vitro.
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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
Studies of the concentration (0–3 mol% PbSe) and temperature (250–670 K) dependences of the lattice thermal conductivity λp in PbTe–PbSe semiconductor solid solutions have shown that in the range of ...0.75–1.25 mol% PbSe an anomalous increase in λp under increasing PbSe concentration takes place in the λp isotherms, plotted as λp/λp0, where λp0 is the lattice thermal conductivity in the absence of PbSe. The observed effect is attributed to critical phenomena and self‐organization processes accompanying the transition from dilute solid solutions to an impurity continuum.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
The dependences of the electrical conductivity, Seebeck coefficient and Hall coefficient on the thickness (d=20–155nm) of the n-type thin films grown on the glass substrates by the thermal ...evaporation in vacuum of the n-type Bi2Te3 topological insulator crystals have been measured. It has been established that these dependences have an oscillatory character with a substantial amplitude. The obtained results are interpreted in terms of quantum size effects, taking into account the peculiar properties of the surface layers of the Bi2Te3 films connected with the topological insulator nature of the bismuth telluride.
•The thickness dependences of Bi2Te3 thin films kinetic coefficients were obtained.•The dependences have oscillatory character with a substantial undamped amplitude.•The oscillation period increases with decreasing film thickness.•The oscillations are attributed to electron confinement in the film growth direction.•It is suggested that topological surface layer affects quantum processes in films.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
The dependences of the Seebeck coefficient
S on the thickness (
d
=
5–110 nm) of SnTe thin films grown by thermal evaporation in vacuum on (001)KCl substrates were obtained at room temperature. ...Distinct oscillations in the
S(
d)-dependences were observed and attributed to the size quantization effect in SnTe thin films. The monotonic component of the
d-dependences of
S decreases with increasing thickness. In this connection it is suggested that the equilibrium concentration of non-stoichiometric cation vacancies depends on the SnTe film thickness.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
An electron microscopy study of the mechanism of SnTe and PbTe layer growth in PbTe/SnTe/PbTe heterostructures prepared by thermal evaporation in vacuum onto a KCl substrate was performed. It is ...established that PbTe and SnTe grow on one another in a layer-by-layer fashion with the introduction of misfit dislocations on the interface at a critical thickness dc~2 nm. The experimentally determined dependence of the elastic stress in a growing layer (either PbTe or SnTe) on the layer thickness and the critical thickness are in good agreement with those calculated theoretically. The dependences of the thermoelectric properties of PbTe/SnTe/PbTe heterostructures on the SnTe layer thickness (dSnTe=5-100 nm) at fixed thicknesses of the PbTe layers were studied at room temperature. It was found that in the thickness range of dSnTe~(10-15) nm, an inversion of the dominant carrier sign from n to p takes place. The d-dependences of the thermoelectric properties were interpreted within the framework of a three-layer model, treating a PbTe/SnTe/PbTe heterostructure as three conductors connected in a parallel fashion, each characterized by its specific electrophysical parameters.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Bi
2
Te
3
compound and Bi
2
Te
3
-based solid solutions have attracted much attention as promising thermoelectric materials for refrigerating devices. The possibility of enhancing the thermoelectric ...efficiency in low-dimensional structures has stimulated studies of Bi
2
Te
3
thin films. Now, interest in studying the transport properties of Bi
2
Te
3
has grown sharply due to the observation of special properties characteristic of three-dimensional (3D) topological insulators in Bi
2
Te
3
. One of the possible manifestations of quantum size effects in two-dimensional structures is an oscillatory behavior of the dependences of transport properties on film thickness,
d
. The goal of this work is to summarize our earlier experimental results on the
d
-dependences of transport properties of Bi
2
Te
3
thin films obtained by thermal evaporation in a vacuum on glass substrates, and to present our new results of theoretical calculations of the oscillations periods within the framework of the model of an infinitely deep potential well, which takes into account the dependence of the Fermi energy on
d
and the contribution of all energy subbands below the Fermi level to the conductivity. On the basis of the data obtained, some general regularities and specificity of the quantum size effects manifestation in 3D topological insulators are established.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
