We construct a spectral representation of neutrino propagator in moving matter or in external magnetic field. In both cases there exists fixed four-dimensional axis of polarization, such that the ...corresponding spin projectors commute with propagator. As a result, all eigenvalues of propagator and, consequently, dispersion laws for neutrino in media are classified according to spin projection onto this axis. Use of the found spin projectors simplifies essentially the eigenvalue problem and allows to build spectral representation of propagator in moving matter or external magnetic field in analogy with the vacuum propagator.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
A new high light yield liquid scintillator based on linear alkylbenzene (LAB) as an organic solvent and a novel nanostructured organosilicon liminophore as a scintillation fluor has been developed ...for the next generation large-scale experiments in astroparticle physics. It is shown that the developed liquid scintillator has light yield almost two times higher than traditional LAB-based liquid scintillator with PPO fluor, when peak light yield values are compared, since the former peaks at 490 nm, while the latter peaks at 360 nm. At the same time light emission kinetics is characterized by about 10 ns decay time constant for its fastest component which contributes more than 80% to the total light yield of the scintillator.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The Navier–Stokes equations were used to carry out the numerical modeling of chemically reactive gas flow in an annular flow chamber. The model was based on laws of conservation of mass, momentum, ...and energy for nonstationary two-dimensional compressible gas flow in the case of axial symmetry with a tangential component of the gas velocity. Viscosity, thermal conductivity, and turbulence were taken into account. Fuel and oxidizer were fed into the chamber separately, and heat release in the chemical reaction zone was largely determined by the rate of turbulent mixing of the gas components. The possibility of burning out of the mixture in the chamber was demonstrated numerically. Detonation failure can occur if reagents temporarily cease to be fed into the chamber, which can be caused by high pressure in the reaction zone. With short combustion chamber lengths, there are the underburning of fuel and the release of unreacted hydrogen into the atmosphere.
This paper describes the numerical modeling of gas flow in a plane vortex chamber by using the Navier–Stokes equations. The model is based on the laws of conservation of mass, momentum, and energy ...for nonstationary two-dimensional compressible gas flow in the case of axial symmetry with a tangential component of the gas velocity. The processes of viscosity, thermal conductivity, and turbulence are accounted for. It is shown that the transition of the kinetic energy of gas into thermal energy as a result of transfer processes leads to the formation of hot spots in the boundary layers near the walls of the chamber. The gas temperature at these hot spots can exceed the gas combustion temperature, while the gas remains rather cold in the neighboring regions. This could be the reason for the cold gas self-ignition observed in the experiments. The turbulence of the flow and the processes of mixing and diffusion of the components make a significant contribution to the capacity of gas self-ignition.
The immunological paradox of pregnancy, when maternal immune system recognizes but does not reject the semiallogenic foetus, is not yet fully understood. The aim of this work was to detail the ...mechanisms of the interaction of decidual CD56+ NK, infiltrating the maternal part of placenta, and trophoblast cells of foetal origin. Samples of the endometrial tissue from 13 healthy non‐pregnant women, 37 placentas, obtained after medical abortion of viable pregnancy at 7–10 weeks of gestation, and 26 samples of placentas from first‐trimester recurrent spontaneous abortion (RSA) were used as the material for investigation. Phenotype of NK was assessed by flow cytometry. The influence of trophoblast cells upon IFNγ and GrB mRNAs expression by dNK was investigated by RT‐PCR. The influence of dNK upon trophoblast cells migration and invasion was studied using collagen and Matrigel systems. In RSA group comparing to the normal pregnancy, the decrease of dNK with inhibitory receptors (NKG2A) and elevation of activated dNK were seen. In normal pregnancy, but not in RSA, trophoblast cells increased the expression of IFNγ and GrB mRNAs by CD56+ dNK. Both in normal and RSA pregnancy, dNK inhibited the migration and invasion of trophoblast cells. Initially, low invasive and migration capacities of trophoblast cells were seen during RSA. Thus, unbalanced activation of dNK can lead to the impairment of dNK and trophoblast cells interaction during RSA.
The possibility of using composite fibers with phase change properties as a thermoregulating additive to dry building mixes (mortar mix) with the possibility of accumulating thermal energy under the ...action of sunlight and a high-frequency alternating magnetic field is studied. Composite fibers were obtained by adsorption of the organic phase-change material eicosane on fibers of microfibrillar cellulose modified with magnetite nanoparticles. The obtained composites demonstrated specific values of stored thermal energy in the range of 129-148 J/g, depending on the content of eicosane in their composition. It is shown that the addition of 10–15% wt. of composite fibers to the dry building mix makes it possible to store and release thermal energy in hardened samples in a temperature range of 27-43°C, corresponding to melting and crystallization of the eicosane in the structure of the composite fibers. It was shown that addition of the composites affects the dynamics of heating under the action of artificial sunlight and subsequent cooling: the samples with added fiber showed more intense heating and slower cooling compared with control samples when the temperature reached 35°C. Samples of the hardened mixture with addition of the composite fibers also exhibited the ability to accumulate thermal energy when exposed to a high-frequency alternating magnetic field with its subsequent sustained removal.
Biopolymeric materials appear as promising eco-friendly and biodegradable matrices for the preparation of composite materials. In this work,
G. lucidum
,
T. hirsuta
,
P. eryngii
,
F. velutipes
,
G. ...applanatum
,
L. edodes
, and
H. erinaceus
fungi strains were studied and the fastest-growing fungi strains were revealed. The growth rate and the morphology of formed mycelium were studied depending on the fungi strain type and employed feeding substrate (malt agar, cellulose microcrystals, cellulose microfibrills). It was shown that the mycelium of
G. lucidum
and
T. Hirsuta
grown on cellulose microfibrils appears as intertwined hyphae with narrow diameter size distribution and has an optimal morphology as a substrate for the preparation of fibrous composite materials. .
In this work, we synthesized samples of carboxylated nanofibrillar cellulose (NFC) and a derivative that is a product of chemical crosslinking of carboxylated NFC with ethylenediamine. The results of ...transmission electron microscopy revealed that crosslinking does not lead to noticeable morphological changes in the NFC structure. The chemical modification of the carboxylated NFC was confirmed by FTIR spectroscopy. It was found that chemical crosslinking of carboxylated NFC with ethylenediamine leads to an increase in the colloidal stability of aqueous suspensions, water retention capacity, and dynamic viscosity of gels. The study of the rheological characteristics showed that the aqueous dispersions of the obtained samples are pseudoplastic liquids and have thixotropic properties.
The spectral representation for the neutrino propagator in moving matter with a constant density has been derived. It has been found that matter includes a four-dimensional axis of complete ...polarization and all poles of the propagator are classified in terms of the projection of the spin on this axis.
This work is devoted to the analysis of the digital tools that a modern teacher should possess to implement the educational process using distance learning technologies. Based on the conducted ...research, the main competencies that a teacher should have to conduct professional activities from the point of view of students were established. Digital tools are urgently needed to implement these competencies. In this paper, we will show our view on the algorithm for using digital tools in the educational process. A teacher should have a wide arsenal of digital tools: be able to use office programs, be able to search, to select, to analyze and to interpret information. To be able to create a teacher’s website, record digital audio and video content, to be able to place it for easy access for students, and, of course, be able to use the University’s learning management system.
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