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The paper presents the results of experimental studies of the arc discharge between the graphite electrodes in an argon atmosphere at a pressure of 0.1–100 kPa. The discharge was ignited after the destruction of a graphite bar heated by a fixed electric current and maintained for ~103 s at a temperature of ~3 kK. Evidence of the formation of liquid phase on the surface of the graphite electrodes at a temperature of ~3.2 kK is presented. Data on the saturated carbon vapor pressure are discussed. The pressure in the carbon triple point does not exceed ~0.1 kPa.

Modeling of cationic and excited states of boron difluoride acetylacetonate and eight of its γ-substituted derivatives was carried out using the methods of outer-valence Green's functions (OVGF), algebraic-diagrammatic construction for the polarization propagator of the second order (ADC(2)), coupled clusters with single and double excitations (EOM-CCSD), and time-dependent density functional theory (TDDFT/CAMB3LYP). Comparison of the calculated data with the absorption spectra made it possible to determine the influence of functional groups on the energies of electronic transitions and the nature of the absorption spectrum bands. Addition of the substituent SPh causes a decrease in the energy gap between the levels of the highest occupied and lowest vacant molecular orbitals, which determine the bathochromic shift of the long-wavelength band in the absorption spectrum relative to the other studied complexes. In the complexes containing Cl, Br, SCN, SEt, SPh and OS(O)2Ph groups in the γ-position, it was found that the highest occupied molecular orbitals are localized mainly on the substituents, and the lowest vacant molecular orbital corresponds to the chelate orbital π4, which determines the presence of transitions with charge transfer. It was shown that the calculated energies of excited states according to the ADC(2) method, in comparison with EOM-CCSD and TDDFT/CAMB3LYP, can be correlated with maxima of the experimental absorption spectra for the lowest average shift (0.27 eV).

The effect of different polyoxyethylene–polyoxypropylene triblock copolymers, their concentration, and mode of action on the loading of poly-(lactic-co-glycolic acid) copolymer-based microparticles containing such medicinal agents as radachlorin (chlorin e6) or ethidium bromide in mesenchymal stem cells was studied. It has been shown that medicinal agents encapsulated inside microparticles affect the loading of these particles in the cytoplasm of mesenchymal stem cells. The number of cells that absorbed the particles with chlorin e6 is approximately two times lower than that in the experiments with ethidium bromide. It has been shown that pretreatment of microparticles with triblock copolymers is more efficient for loading them in cells compared with simultaneous introduction of triblock copolymers and particles into the culture medium. Treatment of ethidium bromide-containing microparticles with triblock copolymers is not efficient for their loading in mesenchymal stem cells compared to the control. The exception is Pluronic 123; when particles are treated with it at concentrations of 1 and 2%, the loading of particles in cells increases compared to the control by factors of approximately 11 and 5, respectively. For particles with chlorin e6, their pretreatment with triblock copolymers at a concentration of 4% is most efficient; the loading of the pretreated particles in cells is increased by factors of approximately 3 to 11.

We present the cases of three patients with severe, life-threatening coronavirus disease 2019 (COVID-19) who had failed to achieve substantial improvement on intial treatment. They subsequently received pulse therapy with methylprednisolone [1,000 mg/day intravenously (IV) for three consecutive days] and IV immunoglobulin (20 g/day). This treatment regimen was associated with a prompt resolution of respiratory failure, elimination of clinical manifestations of the cytokine release syndrome (CRS), and reversal of pulmonary CT changes. The treatment was generally safe and well-tolerated. There was no evidence of protracted persistence of the virus in the patients. Further randomized controlled trials are required to better understand the efficacy and safety of high-dose methylprednisolone and IV immunoglobulin, separately or in combination with each other, in the treatment of severe, life-threatening COVID-19.

Three patients with severe life-threatening COVID-19 who failed to achieve substantial improvement on tocilizumab, received pulse therapy with corticosteroids (methylprednisolone, 1000 mg/day IV for three consecutive days) and intravenous immunoglobulin (20 g/day IV). This was associated with a prompt resolution of respiratory failure, elimination of cytokine release syndrome, and reversal of pulmonary CT changes. The treatment was generally safe and well tolerated. There was no evidence of protracted persistence of the virus in the patients who received pulse therapy. Randomized controlled trials are necessary to specify the efficacy and safety of high-dose methylprednisolone and intravenous immunoglobulin in the treatment of severe life-threatening COVID-19 separately or in combination.

The electronic structure and cationic states of two 1,5-diphenylformazanes and two boron diacetate (B(OAc)2) formazanates were modeled using the outer valence Green's function (OVGF) and density functional theory (DFT) methods. Comparison of data of the OVGF and ultraviolet photoelectron spectroscopy (UPS) methods made it possible to determine an effect of functional groups and complexing agents on energies of cationic states. Addition of NO2-group at the γ-position of the chelate cycle causes stabilization of levels the five upper occupied molecular orbitals (MO) and destabilization of the bonding orbital π3Ph + π3 level. The levels of MOs π3Ph–π3 and n– are stabilized due to influence of the complexing agent B(OAc)2, with a difference in the shift of 0.67 eV. The ionization energies (In) changes for the π-orbitals of benzene rings are within the error of the OVGF method. Under methylation of phenyl groups, the differences between the calculated In, corresponding to the π-orbitals of aromatic substituents, are in good agreement with the experimental In shifts at transition from benzene to toluene. According to the OVGF method, in all the studied complexes the lowest unoccupied molecular orbital (LUMO) is localized mainly on the chelate cycle and has a strong acceptor character, which should contribute the low-lying charge-transfer electronic excitations. Moreover, an application of the DFT analog of the Koopmans' theorem with the BHHLYP and B2PLYP functionals made it possible to determine qualitatively a sequence of cationic states and energy intervals between them in the spectral range up to 10 eV. The DFT/wB97x/cc-pVTZ method data on the energy gap between the highest occupied molecular orbital (HOMO) and LUMO levels correlate with the OVGF/cc-pVTZ calculation results.

The electronic structure of boron difluoride acetylacetonate and its three derivatives was studied using photoelectron and absorption spectroscopy, as well as the density functional theory. In a series of binuclear acetylacetonate complexes containing bridge-moieties of sulfur and selenium atoms, it was found an appreciable mixing of the π 3 -orbital of the chelate cycle with atomic orbitals S 3p and Se 4p resulting in destabilization of the HOMO levels by 0.4–0.6 eV, in comparison with the monomer. The positively charged fragment C(CH 3 )-CX-C(CH 3 ) causes the field effect, which leads to stabilization of the LUMO levels by 0.3–0.4 eV and C 1s-levels by 0.5–1.2 eV. An analysis of the research results on the electronic structure made it possible to determine the effect of substituents in the γ position on the absorption spectra, which is mainly determined by the electron density transfer from the chalcogen atoms to the chelate cycles. It is shown that the calculated energy intervals between electron levels correlate well with the structure of the photoelectron spectra of valence and core electrons.

Dusty plasma structures in glow discharge in helium in the temperature range of 5–300 K are investigated experimentally. We have described the experimental setup that makes it possible to continuously vary the temperature regime. The method for experimental data processing has been described. We have measured interparticle distances in the temperature range of 9–295 K and compared them with the Debye radius. We indicate the ranges of variations in experimental parameters in which plasma–dust structures are formed and various types of their behavior are manifested (rotation, vibrations of structures, formation of vertical linear chains, etc.). The applicability of the Yukawa potential to the description of the structural properties of a dusty plasma in the experimental conditions is discussed.

The electronic structure of Zn(II) bis-beta-diketonate complexes was studied by the methods of ultraviolet photoelectron spectroscopy (PES) (HeI) and electron density functional theory (CAM-B3LYP/cc-pVTZ): acetylacetonate (Zn(acac)2), its thio-analogs with aromatic substituents in the beta positions – Zn(OC(OEt)CHC(C6H5)S)2 and Zn(OC(CH3)CHC(C10H7)S)2. To improvethe analysis of the spectra, the raw spectra were compared with differential spectra (second derivative), the spectra were interpreted using calculations in the outer valence Green functions (OVGF) method. In order to study the electronic effects at substitution of O by S and CH3 by С6Н5 in Zn(acac)2, the electronic structures of Zn(acac)2 and Zn(Sbzac)2 were calculated and analyzed. It is shown that in Zn(bzac)2 the dihedral angles between the planes of cycles of chelate and aromatic substituents are close to 40–45°, that allows π-σ mixing. The splitting of Zn3d-orbitals by ligand fieldinto a1+b1+b2 +e and their mixing with the ligand MOs, shown by the DFT method was used in the interpretation of the PES spectrum.

The electronic structure of Be (II), Mg (II), and Zn (II) acetylacetonates and hexafluoroacetylacetonates was calculated in the DFT approximation. The energies of MOs and ionization energies calculated by the OVGF method were compared with the published data of photoelectron spectroscopy (HeI). The outer valence region of the spectra is equally effectively reproduced by DFT and OVGF methods. The calculations allowed determining the ionization energies of the π2 orbitals of the chelate cycles. It was determined that an increase in the binding energy of the electrons of the valence and core levels upon substitution of CH3>CF3 by 1,7–2,1 eV was correlated with a change of the negative charge of the carbon atom of the substituted groups on positive one. The polarity of M − O bonds increases in the series of Be, Mg, Zn. It was found that in addition to outer valence orbitals, a covalent bonding was also significantly affected by the deep valence σ-orbital 4a1 with a high degree of overlap with metal s-orbitals.

Active physical exercises and growth are associated with mineral imbalances in young athletes. The purpose of this study was to examine the impact of sport-related factors on tissue mineral status in adolescent female athletes. Saliva and hair samples were used for the analysis of immediate and more permanent tissue mineral status, respectively. Samples taken from a control non-athletic female group and two groups of female athletes (field hockey and fencing) were analyzed for seven essential minerals: calcium, chromium, iron, potassium, magnesium, selenium and zinc. Inductively-coupled plasma mass spectrometry was used for the quantification of elements having very low concentration range in samples (Se, Cr and Zn) whereas inductively coupled plasma optical emission spectrometry was used for quantification of more ubiquitous elements (Mg, К, Са, Fe). The obtained results for athletic groups were compared with control. Female athletes had increased levels of selenium in both saliva and hair as well as chromium in saliva. Field hockey players had the higher level of zinc in hair whereas fencers had the lower levels of salivary calcium. Strong negative correlation between potassium levels in saliva and hair was identified. Iron and magnesium did not differ between the studied groups. In conclusion, novel sport-specific features of chromium tissue levels in female athletes were found. The studied sport disciplines have different impact on the distribution of osteoporosis-related minerals (calcium and zinc). Our finding can help in the development of osteoporosis preventive trainings and in the proper nutrient supplementation to correct mineral imbalances in female athletes.

A model making it possible to calculate the emission currents in a cathode and its volt-ampere characteristic (VAC) taking the phenomena in the near-cathode plasma layer into account is proposed. The effect of plasma electrons and ions, thermal field-emission processes, and radiation from the plasma and evaporation of the cathode material are taken into account. The fields of the electrical potential and temperature in the cathode body, with the Joule heat release taken into account, are calculated. The numerical simulation yielded the conditions causing the volt-ampere characteristic ambiguity in the near-cathode layer in the absence of a liquid cathode spot. The obtained characteristics make it possible to estimate the lifetime and efficiency of a plasmotron with a tungsten cathode and argon serving as an actuating medium used in a number of plasma technologies.

Signal processing is one of the most important system control mechanisms across a wide variety of functional devices and mechanisms from electronics to biology. The chemical reaction networks underlying the response of a cell to both externally and internally generated signals comprise an extraordinary real-time multivariate control problem. There are two phenomena that exemplify the biological importance of chemical systems' response to oscillatory signals. One includes a number of important cases of differential cellular response to particular frequencies of periodic chemical signals. The most widespread example of this is the encoding of an external agonist concentration in the frequency of calcium ion concentration spiking inside certain eukaryotic cells. The second is based on the fact that, owing to the low concentrations and slow reaction rates often associated with, for example, the mechanisms of gene expression, a significant amount of fluctuation in protein production rates is to be expected. Th...

Rock-forming amphiboles of alkaline rocks and carbonatites - richterite, magnesioarfvedsonite, and magnesioriebeckite belong to the isomorphic series with gradual change of the L/M ratio, where L = 3-5 is mainly Mg 2 + and M = 0-2 is mainly Fe 3 + . The studied representatives of this series from carbonatites of Eastern Siberia are characterized by L/M = 1.4-35 with the variations of L from 4.86 (with M = 0.14) down to 2.94 (with M = 2.06). Richterite-magnesioarfvedsonite and magnesioarfvedsonite-magnesioriebeckite parts of the considered isomorphic series are characterized by different mechanisms of isomorphic replacement. The main isomorphic effect for the richterite-magnesioarfvedsonite part may be represented by the scheme: Ca 2 + +L 2 + ←Na B 1 + +M 3 + with the possibility of total replacement of Ca by Na in the B-group. The main isomorphic effect for magnesioarfvedsonite-magnesioriebeckite part may be represented by the scheme: A 1 + +L 2 + ←M 3 + with the variation of the value of the A-group from 0-1. The clear correlation between the value of the M formula subgroup and optical properties (refractive indices n z and n x , birefringence, pleochroism, optical elongation) characterize the amphiboles of richterite-magnesioarfvedsonite-magnesioriebeckite series.

1. X-ray diffraction patterns of natural and heat-treated anthracites, graphites, pyrolytic carbon, schungite, and polyacetylene contain, besides graphitic reflections, a significant number of other, nongraphitic, reflections. A portion of them is caused by heteroatomic fragments and disappears upon heating, but other reflections, on the other hand, grow during heat treatment. 2. The basic mass of carbonaceous material in the original anthracites, polyacetylene, and schungite exists not in the form of graphitoid substances, but in the form of partially crosslinked, spatially branched carbon chains, containing, perhaps, secondary fragments. 3. During heating, the processes of aromatization and graphitation spread, and the lamellar structure is formed. In a parallel manner, crystalline fragments of nongraphitic nature are formed. 4. Upon heating, anthracites twice transform into the thermoplastic state.