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•Combination of SHS and HP use to obtain ceramics in the ZrSi2-MoSi2-ZrB2 system.•Kinetics of oxidation at 1400 °C described using a power function with index n > 2.•Mostly the ZrSi2 ...phase were oxidized.•Two-layer film formed during oxidation consist of silicate glass and ZrSiO4 sublayer.•ZrSiO4 with scheelite-type structure encapsulate the ZrB2 and MoSi2.
The results of a study of the kinetics and mechanism of heterogeneous and compact ceramics oxidation in the ZrSi2-MoSi2-ZrB2 system at air temperature of 1400 °C are presented. The ceramics were obtained by the hot-pressing of composite powders that were manufactured by self-propagating high-temperature synthesis following the magnesiothermal recovery approach. Oxidation kinetics are described using a power function with index n>2, confirming the significant influence on the evolution process in the structure of the formed oxidation coating. The oxidation mechanism includes the formation of a two-layer structure consisting of a continuous silicate film, of which the outer part contains magnesium and a sublayer based on the ZrSiO4 phase, with the scheelite structure encapsulating the ZrB2 and MoSi2 grains. The influence of the ZrSi2, MoSi2 and ZrB2 phases on the structural-morphological peculiarities of the appearing oxide films and the effectiveness of its protective action are revealed.
Polymorphism of genes of transforming growth factor
TGFB
and its receptors (
TGFBRI
,
TGFBRII
, and
TGFBRIIII
) in patients with primary open-angle glaucoma was analyzed. The frequency of the
TGFBRII ...CC
genotype in patients is increased relative to the control group (OR=6.10,
p
=0.0028). Heterozygosity in this polymorphic position is reduced (OR=0.18,
p
=0.0052). As the effects of TGF-β is mediated through its receptors, we analyzed complex of polymorphic variants of the studied loci in the genome of patients. Two protective complexes consisting only of receptor genes were identified:
TGFBRI TT:TGFBRII CG
(OR=0.10,
p
=0.02) and
TGFBRII CG:TGFBRIII CG
(OR=0.09,
p
=0.01). The study showed an association of
TGFBRII
polymorphism with primary open-angle glaucoma and the need to study functionally related genes in the development of the disease, which should contribute to its early diagnosis and prevention.
The work presents the first data on sulfide mineralization in carbonate–silicate veins, which are widespread on the islands and coast of the White Sea (North Karelia), associating with Early ...Proterozoic metamorphosed gabbroid bodies. The veins with Fe–Cu sulfide mineralization up to ore occurrences are localized within metabasite bodies and along their contacts with host gneisses. During the study of the mineral composition of the veins, the main assemblages of sulfide minerals were identified: chalcopyrite –bornite ± chlorite ± selenides and Pb–Ag tellurides (B1); digenite–bornite ± selenides and Pb, Ag, and Pd tellurides (B2); pyrite–bornite ± chalcopyrite (B3); marcasite–pyrite–bornite–chalcopyrite (B4); and siegenite–chalcopyrite ± acanthite ± chlorargyrite. The development of sulfide associations, as well as quartz–chlorite aggregates, was related to the late stage of vein formation. Inductively coupled plasma and laser ablation mass spectrometry analyses showed that bornite from association B1 has the highest silver content (up to 675 ppm) and, in terms of Ag, Se, and Bi contents, is closest to bornite from low-temperature epithermal, skarn, and high-temperature vein deposits. In general, bornite is the main Ag carrier in the studied associations, while digenite containing up to 1000 ppm Ag, as well as discrete silver minerals (selenides, tellurides, acanthite, and chlorargyrite), occur in subordinate quantities. Fluid inclusions in quartz from sulfide associations, as well as from a sulfide-free carbonate–silicate vein, were studied by cryo- and thermometric methods. It is established that mineralization at the late stages of vein formation was related to heterogeneous CO
2
–H
2
O–NaCl metamorphic fluid. Carbon dioxide fluid inclusions were captured by vein quartz at temperature of 253–314°C and pressure of 2 ± 1 kbar. Water–salt inclusions were captured in a wider temperature range of 100–500°С. The highest temperature fluid inclusions with temperatures of homogenization >300°С are characteristic of quartz veinlets of the siegenite–chalcopyrite association with Ag sulfide and chlorargyrite.
The physicochemical interaction in the ZrSi
2
–ZrSiO
4
system at temperatures higher than 1620°C under the conditions of molecular oxygen deficiency is established and experimentally confirmed. ...Elemental silicon is reduced simultaneously with the oxidation of zirconium to the thermodynamically stable ZrO
2
phase. The mechanism and steps of the interaction processes are proposed.
A review is presented of the latest technologies for vertex detectors that can be used in experiments at the NICA collider. These technologies include both the novel pixel detectors with new ...ultralight radiation-transparent carbon composite structures and cooling systems. The efficiency of reconstructing
D
meson decay is estimated for the developed detector complexes, and the possibility of using these complexes to study the formation of clusters of cold, dense quark-gluon matter inside nuclei are studied.
Nuclear technologies for producing radioactive isotopes are considered with a focus on the radionuclides used as radiopharmaceuticals in state-of-art methods of cancer diagnosis and radionuclide ...therapy—theranostics. New target materials and nuclear reactions for producing these radionuclides are considered. Results are presented from experimental and theoretical studies of the excitation functions of (
p
,
xn
) reactions in the 6–80 MeV range of energies for medium mass nuclear systems to produce such radionuclides as scandium, technetium, antimony, and terbium. These radionuclides are promising for their use in the diagnostics, therapy, and theranostics of nuclear medicine.
Despite the local occurrence of silicic magmatism during the formation of the oceanic crust, the nature of felsic granitoid veins (“oceanic plagiogranite”) remains an important debatable problem of ...chemical differentiation in the global system of mid-oceanic ridges. To date, the actual compositions of granitoid melts in the modern oceanic crust are still poorly constrained, and this complicates petrogenetic interpretations. The structural patterns and compositional variations of minerals from the oceanic core complex at 13° N on the Mid-Atlantic Ridge show the sequence of magmatic differentiation: coarse-grained gabbronorite → vein microgabbro enriched in Fe–Ti oxides and apatite → biotite–plagiogranite veins. The transition to silicic magmatism corresponds to the local crystallization of quartz and zircon in the vein microgabbro with the further Zr/Hf fractionation by zircon. Experimental study of melt inclusions in zircon demonstrated homogenization at 850–910°C and the granitoid composition of the melt with K
2
O >1.8 wt % and SiO
2
of 75–76 wt %. Such a K/Si ratio of the silicic melt, along with the genetic relation to highly differentiated gabbroids, allows us to prefer the model of a high degree differentiation of MORB-type magma in the oceanic core complex for the studied plagiogranite–gabbro association.
The plutonic rocks studied in the Ashadze Complex contain four groups of mineral assemblages: (I) coarse-grained gabbronorite, which is dominant; (IIa) micrograined differentiated gabbro (oxide ...microgabbro) enriched in ilmenite and apatite and sporadically containing zircon grains smaller than 70 µm; (IIb) local oxide microgabbro aggregates with zircon grains as large as 200 µm and quartz; and (III) biotite- and orthopyroxene-bearing plagiogranite veinlets. As an interpretation, a model of sequential differentiation of MORB-type melt is proposed. The compositional variations of the plagioclase and orthopyroxene are consistent with the general sequence of crystal fractionation and show partial overlap of assemblages (II) and (III). In the sequence of zircon-bearing assemblages (IIa), (IIb), and (III), zircon shows a systematic enrichment in Hf. Zircon of assemblage (IIb) hosts melt inclusions. The inclusions were completely remelted at 910°C and quenched into homogeneous glass. The analyzed granitoid (75–76 wt % SiO
2
) water-bearing (H
2
O ~ 3 wt %) composition of the inclusions was interpreted as a residual melt after crystallization of the evolved vein gabbro rich in ilmenite. The results offer an example of an evolved granitoid product of MORB differentiation and are consistent with high-degree magmatic differentiation in the oceanic crust, a model according to which the crystallization of evolved oxide gabbro results in a residual silicic melt.
Coronavirus SARS-CoV-2 was the cause of global pandemic COVID-19 that has claimed millions of lives around the world. One of the approaches to the therapy of severe forms of COVID-19 is based on the ...use of virus-neutralizing antibodies against the receptor-binding domain (RBD) of the virus spike glycoprotein (S). Detailed structural data on particular epitopes recognized by these virus-neutralizing antibodies is an important aspect of the improvement of available antibodies in order to extend the range of recognized virus strains. A stoichiometric complex of the virus-neutralizing single-domain antibody P2C5 and the glycosylated form of SARS-CoV-2 S protein RBD was obtained. Despite numerous conditions in which the crystal growth of the complex was observed, these crystals showed poor diffraction, apparently because of heterogeneity associated with the glycosylation of RBD. With the aim of improving the crystal quality, deglycosylase PNGase F was produced in a bacterial expression system and deglycosylation of RBD was performed. Despite low solubility of the deglycosylated form of RBD, it retains the ability to bind to the nanoantibody P2C5, resulting in the formation of a stable heterodimeric complex during gel filtration. The crystals of this complex were obtained. They showed diffraction to a similar resolution of ~4 Å on a laboratory X-ray diffractometer and at a synchrotron radiation source. The symmetry space group, the unit cell parameters of the crystal, and its protein composition were determined.
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