The development of new strategies for the mass synthesis of SiC nanocrystals with high structure perfection and narrow particle size distribution remains in demand for high-tech applications. In this ...work, the size-controllable synthesis of the SiC 3C polytype, free of sp2 carbon, with high structure quality nanocrystals, was realized for the first time by the pyrolysis of organosilane C12H36Si6 at 8 GPa and temperatures up to 2000 °C. It is shown that the average particle size can be monotonically changed from ~2 nm to ~500 nm by increasing the synthesis temperature from 800 °C to 1400 °C. At higher temperatures, further enlargement of the crystals is impeded, which is consistent with the recrystallization mechanism driven by a decrease in the surface energy of the particles. The optical properties investigated by IR transmission spectroscopy, Raman scattering, and low-temperature photoluminescence provided information about the concentration and distribution of carriers in nanoparticles, as well as the dominant type of internal point defects. It is shown that changing the growth modes in combination with heat treatment enables control over not only the average crystal size, but also the LO phonon—plasmon coupled modes in the crystals, which is of interest for applications related to IR photonics.
The structural, electrical, and magnetic properties of lithium zinc ferrite prepared by ceramic technology have been studied. The composition of lithium zinc ferrite is Li
0.4
Fe
2.4
Zn
0.2
O
4
with ...1 and 2 wt % bismuth oxide. The addition of Bi
2
O
3
prior to sintering of the samples has been shown to affect the structural, electrical, and magnetic properties of the ferrite. A significant increase in density from 4.47 to 4.65 g/cm
3
and a decrease in porosity from 4.8 to 2.3% have been observed when the concentration of bismuth oxide has been increased to 2 wt %. The Bi
2
O
3
-containing samples have higher specific electrical resistivity compared to that of the additive-free lithium zinc ferrite. The introduction of bismuth oxide has reduced the specific saturation magnetization from 70.55 to 54.76 G cm
3
/g. The Curie temperature has not changed significantly. An optimal combination of macroscopic properties of ferrite has been found at 1 wt % Bi
2
O
3
concentration.
This paper considers an original valve electromagnet with integrated armature, designed to implement an electromagnetic overcurrent release of a circuit breaker. Theoretical and experimental studies ...of the proposed electromagnet have been carried out to determine the most important parameters of circuit breakers such as sensitivity and high-speed performance. Calculations and experiments have shown the possibility of increasing the sensitivity and speed of the electromagnetic overcurrent release based on the proposed electromagnet with integrated armature in comparison with existing structures used in modern circuit breakers.
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The paper presents results of petrological and geochemical studies of sulfide-bearing rocks from a bottom apophysis in the central part of the Yoko-Dovyren massif, northern Transbaikalia, Russia. ...It is composed of plagioperidotite and was sampled in a bulge up to 300 m thick throughout the whole vertical section, from its upper to lower contact. The observed diversity of sulfide-bearing rocks is subdivided into four types: (1) picrodolerite with droplet-shaped sulfides, (2) olivine gabbronorite with sulfides varying from droplet-shaped to irregular globules, (3) olivine gabbronorite with larger globules and patchy net-textured domains, and (4) net-textured ores. These varieties occur in the basal zone of the apophysis, in the interval up to 30 m inward from the lower contact. Petrographic features of these rocks correspond to olivine ortho- and mesocumulates, with the only exception of the quenched picrodolerite with an ophitic groundmass. The association of sulfides (pyrrhotite, chalcopyrite, pentlandite, and cubanite) has a pretty little varying composition, except only a relative decrease in the proportion of chalcopyrite in samples with more than 5% sulfides. The results of X-ray computed tomography show an increase in the sulfide connectivity in the rocks (from 25 to 95%) with increasing sulfide abundance. These characteristics, supported by visualized 3D models, allowed us to identify a morpho-structural trend tended from the rocks with sulfide droplets to the net-textured ores. The first ever data were obtained on the chemostratigraphy (PGE and tellurium) of rocks composing this apophysis. Covariations of Au, Pt and Pd with S and Te indicate that the precious metals have a single sulfide precursor. The 100%-sulfide compositions calculated for these rocks indicate that the most primitive and PGE rich sulfides correspond to droplets it the lowerest part of the apophysis, whereas the net-textured ores are depleted in these elements. The geochemical estimates are supported with COMAGMAT-5 modeling which made it possible to calculate the average Au, PGE, and Te contents in the protosulfide melt (in ppm): 2.9 Au, 14.4 Pt, 25.1 Pd, and 44.3 Te. Results of the geochemical studies of different fragments of the net-textured ores reveal a heterogeneity in the form of domains relatively enriched in copper, PGE, and tellurium, whose characteristic size is a few dozen centimeters. This can be considered as a signature of the porous migration and accumulation of the crystallization products of the original sulfide liquid at the subsolidus stage of cooling down the ore-bearing cumulates.
Many biochemical pathways are driven by G protein-coupled receptors, cell surface proteins that convert the binding of extracellular chemical, sensory, and mechanical stimuli into cellular signals. ...Their interaction with various ligands triggers receptor activation that typically couples to and activates heterotrimeric G proteins, which in turn control the propagation of secondary messenger molecules (e.g. cAMP) involved in critically important physiological processes (e.g. heart beat). Successful transfer of information from ligand binding events to intracellular signaling cascades involves a dynamic interplay between ligands, receptors, and G proteins. The development of Förster resonance energy transfer and bioluminescence resonance energy transfer-based methods has now permitted the kinetic analysis of initial steps involved in G protein-coupled receptor-mediated signaling in live cells and in systems as diverse as neurotransmitter and hormone signaling. The direct measurement of ligand efficacy at the level of the receptor by Förster resonance energy transfer is also now possible and allows intrinsic efficacies of clinical drugs to be linked with the effect of receptor polymorphisms.
GPCR studies in live cells have revealed kinetics and rate-limiting steps in receptor-mediated signaling, and have linked receptor polymorphisms and drug selectivity.
For the first time, the peculiarities of the blood proteomic composition depending on the predominance of the vegetative regulation type were analyzed under the conditions of dry immersion in women ...volunteers (age 30.17 ± 5.5 years, height 1.66 ± 0.1 m, weight 62.05 ± 8.4 kg, BMI 22.39 ± 2.2 kg/m
2
) with a natural menstrual cycle. The experiment “NAIAD-2020” was carried out at the Institute of Biomedical Problems (Moscow, Russia). It has been shown that under normal motor activity (in baseline studies), in individuals with various modulating types of autonomic influences, energy expenditure is provided mainly by carbohydrate metabolism, which has genetic features in the implementation of the pentose pathway. During dry immersion, with minimal motor activity, energy expenditure sharply decreases, leveling out vagus-mediated differences between the groups. On the second day of the recovery period, processes related to the functions of heat shock proteins and excosomes were noted.
A recent report on obtaining the n-type conductivity in diamonds doped with boron–oxygen complexes in a metal solvent (X. Liu et al., PNAS 2019) stimulates interest in the synthesis of diamonds in ...heterohydrocarbon systems with oxygen and boron. The simultaneous effect of boron and oxygen heteroatoms on phase transitions in a hydrocarbon system is examined in phenylboronic acid C6H5B(OH)2 at pressures of 7–8.5 GPa and temperatures up to 1600 °C. At pressures of about 7 GPa and temperatures up to 1100 °C, the transformation of the precursor occurs through the stage of polymerization into a graphane-like phase with the subsequent formation of nanographite. Micro- and nanodiamonds are synthesized at 8.5 GPa and 1600 °C from the initial precursor and nanographite, which is a product of preliminary carbonization, respectively. Despite the presence of oxygen and boron in the growth system, the n-type conductivity in diamonds and nanographite is not detected. It is found that the degree of boron doping of diamond in hydrocarbon systems decreases in the presence of oxygen with a high chemical affinity to boron and that nanodiamonds in the carbonized product can be obtained when volatile components leave the system.
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•Synthesis of diamonds from phenylboronic acid C6H5B(OH)2 was studied at 7.5–8.5 GPa.•The n-type conductivity in diamonds due to co-doping with B and O is not detected.•Removing volatile components from carbonized precursor facilitates formation of nanodiamonds.•Introduction of oxygen to hydrocarbon system reduces concentration of boron in diamond.
We obtain the Carnahan–Starling equation for a system of hard spheres using the Euler method of accelerated series convergence. For this purpose, the virial series is transformed into a new series ...with coefficients that differ slightly from each other, even when considering the eleven currently known virial coefficients. The method of accelerated convergence was applied to this series; it allowed us to obtain the Carnahan–Starling equation. In this work, this equation is derived for the first time using the method of accelerated convergence. It is generalized to accurately reproduce all of the known virial coefficients and the asymptotic behavior of the free energy at high densities. This also makes it possible to describe a metastable region with a high degree of accuracy and to obtain the equation of state for a homogeneous system of hard spheres with the accuracy of a computer experiment.
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