The effects of composite fibroin-gelatin microparticles (100-250 μ) on the rate of wound healing and regeneration under conditions of contraction prevention were studied on the model of splinted ...full-thickness skin wound in a mouse. Subcutaneous injection of these particles into the defect area accelerated wound healing and promoted re-epithelialization and recovery of normal structure of the epidermis. In addition, the composite microparticles promoted the formation of connective tissue of characteristic structure, replacing the derma over the entire defect, and stimulated regeneration of subcutaneous muscle (panniculus carnosus) and skin appendages (sebaceous glands and hair follicles).
X-ray structural analysis and photoluminescence spectroscopy techniques were used to study heterostructures based on InGaAs/InAlGaAs superlattice for active regions of 1300 nm range lasers grown by ...molecular beam epitaxy. It is shown that the grown heterostructures have a high crystal quality. The perpendicular lattice mismatch of the average crystal lattice constant of the InGaAs/InAlGaAs superlattice with respect to the crystal lattice constant of the InP substrate is estimated at ~ +0.01%. An analysis of the photoluminescence spectra made it possible to conclude that the contribution of Auger recombination is insignificant in the studied range of excitation power density. Studies of vertical-cavity surface-emitting lasers with an active region based on the InGaAs/InAlGaAs superlattice made it possible to estimate the gain coefficient at a level of 650 cm
–1
for the standard logarithmic approximation of the dependence of the gain on the current density. The transparency current density of the laser was 400–630 A/cm
2
, which is comparable to the record low values for the case of highly strained InGaAs–GaAs and InGaAsN–GaAs quantum wells in the spectral ranges of 1300 nm, respectively.
The thermal stability of a bimetallic wire made of three novel aluminum alloys Al–0.25 wt % Zr with different Sc and Hf contents has been investigated. A wire made of pure aluminum A99 and ...Al‒0.25 wt % Zr alloy was studied as an object of comparison. Alloys were obtained by injection molding in vacuum. Cast samples were subjected to severe plastic deformation and annealing, which ensured the formation of a uniform microstructure and the release of stabilizing Al
3
(Zr,Sc,Hf) nanoparticles. The wire 0.26 mm in diameter was obtained by joint deformation of an aluminum alloy with a copper shell by rolling in rolls. The effect of annealing for 30 min in the temperature range from 200 to 500°C on the parameters of the microstructure and mechanical properties (microhardness, ultimate strength, ductility, specific electrical resistivity) of the wire was studied. The wire has high strength and increased thermal stability. After annealing at a temperature of 500°C, a homogeneous fine-grained structure with a grain size of 3–5 μm was formed in the wire; increased hardness and ultimate strength of the samples was observed owing to the separation of Al
3
(Zr,Sc,Hf) particles. There is an intense diffusion of copper from the shell into the surface layers of the aluminum alloy, which can lead to embrittlement of the wire.
We investigate both experimentally and theoretically the role of migration effects in a relaxation of the ensemble of Si crystallites formed in multilayer SiOx/SiO2 nano-periodic structure with ...annealing. Photoluminescence spectrum of the multilayer ensemble turns out to be strongly redshifted and narrowed related to its position and width expected from the size distribution of the nanocrystals. Based on the concept of “quantum confinement” we have performed a computer experiment on the ensemble relaxation with taking the migration of electrons, holes, and excitons into account for the ensemble having the size distribution and nanocrystals׳ density similar to those in the experimental sample. This model allows us to calculate the photoluminescence spectrum that agrees well with the one observed experimentally. It was shown experimentally and theoretically that in a dense ensemble, the migration quenches the luminescence of Si nanocrystals whose diameters are, in fact, less than the average nanocrystal diameter in the ensemble. This explains the above mentioned features of the measured spectrum.
•Simulation of luminescence in dense ensembles of silicon nanocrystals was carried out.•Concurrence of radiative transitions and energy transfer is studied in the ensemble.•Smaller nanocrystals transfer their excitation to the greater ones, and become “dark”.
Morphofunctional activity of mast cells in renal cancer is studied on specimens from the center of the tumor, peritumorous zone (with an obligatory fragment of the pseudocapsule), and from renal ...tissues maximally distant from the tumor. The counts and areas of tumor cells were maximum in the peritumorous zone in comparison with intact kidney tissue and central zone of the tumor. Analysis of correlations revealed a direct correlation between the tumor cell count in the peritumorous zone and some clinical morphological parameters of the tumor (anaplasia degree, size, presence of invasion and metastases, and angiogenesis). The count of mast cells in the renal peritumorous zone inversely correlated with 5-year survival: 100% cumulative 5-year survival in patients with mast cell count <6.7±1.6 per field of view.
Hybrid materials based on organically modified silica with immobilized boron-dipyrrins (BODIPY) dyes were obtained. Spectral characteristics of the dyes were measured during the matrix formation and ...in obtained materials. It was stated, that immobilization does not affect the character of the absorption and fluorescence spectra of the dye, but due to the effect of fluorescent molecular rotor observed for
meso
-substituted BODIPY, the fluorescent quantum yields were found to increase during the matrix sealing. Quantum yield increase is linear for all of the investigated matrices except phenyl-substituted one, where the π-π interactions of the dye molecule with matrix could be observed. This effect could be used for fine control of the matrix formation process and leads to increase of the dye emission in the final material for further practical applications. All obtained hybrid materials were found to be stable upon UV light irradiation, hence immobilization enhance the stability of the dye in comparison with the BODIPY in organic solvents.
Coherent narrow resonances in a homogeneously broadened contour of selective reflection from the interface between a cell window and high-density atomic rubidium vapor, where the dipole broadening ...greatly exceeds the Doppler width of the unresolved components of rubidium
D
2 line, are discussed. The formation of coherent resonances is caused by the coherent scattering of probe and pump optical fields from the oscillations of populations of the ground and excited states of atoms at the beat frequency. The width of each resonance depends on the population difference decay rate. Within a simple model conditions are found for observing resonances with a Lorentzian spectral profile. The experimentally recorded coherent resonances are described by a Lorentz function with fitting parameters in the form of amplitude, width, and spectral baseline. In the limit of zero optical saturation the measured half-width of a coherent resonance (HWHM) γ
res
/2π is about 52 MHz, which greatly exceeds the radiative decay rate of the rubidium excited state 5
P
3/2
.
Based on the data of atomic modeling, the different schemes of isomorphic incorporation of Cr
3+
ions into the crystal structures of CaSiO
3
and MgSiO
3
were tested in the pressure range of 18–25 GPa ...and at temperatures of 1873–2223 K. Under these
PT
parameters, the content of Cr
3+
in these structures was estimated quantitatively. The semi-empirical simulation data are in good agreement with the results of experiments.
We have developed far-off resonance single beam dipole trap for optically cooled lithium-7 atoms. In the present paper we discuss some preliminary results. In order to improve performance of the trap ...we optimized the trapping time and increased the atoms number. The lifetime was increased by improving the vacuum from ≈ 3 × 10−10 Torr to ≈ 10−11 Torr and preparing all the atoms in the selected atomic state (the lower ground state level). After vacuum improvement the single particle losses in the magneto-optical trap was reduced by 100 times and as the result the lifetime in the dipole trap reached 25 s.
An experimental study of the self electromagnetic field generated by the low-temperature plasma of the fuel combustion products of a model liquid-propellant rocket engine is carried out. The fuel ...components were gaseous oxygen and ethyl alcohol. When modeling emergency situations in the operation of the model rocket engine, the intensity of its self electromagnetic field generated by the ionized products of fuel combustion was recorded. A linear dependence of the self magnetic field strength on the pressure in the combustion chamber in the range 2.2–3.5 MPa was established. The feasibility of noncontact electrophysical methods for diagnosing the working process in aircraft power plants using as a useful signal the value of the magnetic field strength is shown.
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