The chemistry of organoelement compounds is now one of the most rapidly developing fields of research, regarding both fundamental science and solution of applied problems. This review covers a ...variety of classes of organoelement compounds, ranging from molecules with highly labile carbon-element bonds to compounds with stable bonds that form the basis of novel structural materials and demonstrates their role in scientific research and industrial production. The use of Grignard reagents in modern organic synthesis and application of catalytic cyclomagnesiation and cycloalumination reactions for the preparation of difficult-to-access metallacycles are considered. The electron transfer processes in redox-active derivatives of Group 14 elements and the role of radical ions in these processes are discussed. Considerable attention is paid to organometallic compounds, first of all, as catalysts; the dynamic nature of catalysis with these compounds is noted. Unusual strained metallacycles of high thermal stability, zirconacyclocumulenes, which also exhibit catalytic activity, are described. Complexes with redox-active ligands that substantially affect the reactivity of the metal centre and directly participate in reactions with various substrates as well as organometallic compounds of lanthanides are considered. Modern environmentally benign methods for the synthesis of organosilicon compounds and production of unique materials based on them are discussed. Particular Sections are devoted to organophosphorus compounds, including those exhibiting therapeutic properties and possessing unusual optical characteristics, and organic chalcogen compounds, which find use as ligands and biologically active molecules. The bibliography includes 1045 references.
Aluminum nanopowders are widely used in powder metallurgy, pyrotechnic industry, and chemical technologies. Aluminum nanopowder properties such as thermal effect of oxidation can be improved by the ...incorporation of different chemical additions. Different chemical additions in nanopowders are usually used for changing of some properties such as thermal oxidation effect or starting oxidation temperature. This study examines the influence of an absorbed dose of the electron beam irradiation on a thermal effect of oxidation for aluminum nanopowders. A thermal oxidation effect has been increased for the samples from 7898 J/g by 18.0% after 0.4 MeV and by 16.7% after 4.0 MeV electron beam irradiation for the same absorbed dose of 50 kGy. For the same time starting oxidation temperature was decreased by 5% on absolute (Kelvin) scale only for the sample irradiated by 4 MeV electron beam.
•The electron beam influence on the thermal properties of aluminum powder was studied.•Aluminum nanopowder irradiation results in changing in the thermal oxidation effect.•An increase in the absorbed dose leads to an increase in thermal effect of oxidation.•An absorbed dose is more significant than the kinetic energy of electrons.•The kinetic energy of beam electrons can be chosen depending on the sample thickness.
Tetrakisquaternary ammonium compounds based on pentaerythritol were synthesized for the first time. Bacteriostatic effect of the obtained compounds was evaluated towards opportunistic gram-positive
...Methicillin-resistant Staphylococcus aureus
(strain ATCC 25923), gram-negative
Escherichia coli
(ATCC 25922), and
Pseudomonas aeruginosa
(ATCC 27853). The activity of reported salts was evaluated competitively with that of known antiseptics, Octenidine Dihydrochloride and Chlorhexidine Digluconate. The effect of length of the alkyl substituent in the salts on their biological activity was established. These new compounds are based on available pentaerythritol and 3-hydroxypyridine.
Hepatitis B virus core antigen (HBc) with the insertion of four external domains of the influenza A M2 protein (HBc/4M2e) form virus-like particles whose structure was studied using a combination of ...molecular modeling and cryo-electron microscopy (cryo-EM). It was also shown that self-assembling of the particles occurs inside bacterial cells, but despite the big inner volume of the core shell particle, purified HBc/4M2e contain an insignificant amount of bacterial proteins. It was shown that a fragment of the M2e corresponding to 4M2e insertion is prone to formation of amyloid-like fibrils. However, as the part of the immunodominant loop, M2e insertion does not show a tendency to intermolecular interaction. A full-atomic HBc-4M2e model with the resolution of about 3 Å (3.13 Å for particles of Т = 4 symmetry, 3.7 Å for particles of Т = 3 symmetry) was obtained by molecular modeling methods based on cryo-EM data.
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•Peptide, corresponding to influenza A M2 protein ectodomain prone to the formation of amyloid-like aggregates•The HBc/4M2e VLPsare seem to self-assembled inside the bacterial cells due to high aggregation propensity of the monomers•The HBc antigenic loop containing 4M2e does not possess stable spatial structure•The 4M2e insertion into the “antigenic loop” is localized outside the HBc/4M2e particle
The influenza NS1 protein is involved in suppression of the host immune response. Recently, there is growing evidence that prion-like protein aggregation plays an important role in cellular signaling ...and immune responses. In this work, we obtained a recombinant, influenza A NS1 protein and showed that it is able to form amyloid-like fibrils in vitro. Using proteolysis and subsequent mass spectrometry, we showed that regions resistant to protease hydrolysis highly differ between the native NS1 form (NS1-N) and fibrillar form (NS1-F); this indicates that significant structural changes occur during fibril formation. We also found a protein fragment that is capable of inducing the process of fibrillogenesis at 37 °C. The discovery of the ability of NS1 to form amyloid-like fibrils may be relevant to uncovering relationships between influenza A infection and modulation of the immune response.
•Recombinant NS1 protein is capable of forming amyloid-like fibrils.•Native form NS1 features a protease-resistant fragment from a.a. residues 1 to 78.•The fibrillar NS1 form's C-terminus is hydrolyzed by trypsin least of all.•During fibril formation, SDS-resistant non-native dimers form.•The NS1 Beta domain likely plays an important role in conformational transition.
The ultraviolet (UV)-C range ensures high noise immunity and the possibility of operating equipment in the troposphere during the daytime, since the ozone layer of the atmosphere almost completely ...absorbs the UV-C radiation from the Sun. One of the main advantages of this range in comparison with the visible, infrared, and even radio range is the weak scattering of ultraviolet on aerosol particles of dust, snow, hail, water droplets, fog, and rain. In this paper, we propose a method for determining the optical thickness of the atmosphere during the propagation of UV-C radiation along an inclined path over the sea. Accounting for the inhomogeneity of the path of propagation of UV-C radiation is ensured by introducing in the model the dependence of the extinction coefficient and the optical thickness of the atmosphere on altitude. The validity of the proposed model is confirmed by the data of a full-scale experiment conducted over the Black Sea. The extinction coefficient of the atmosphere above the sea surface, as well as its aerosol and molecular components, is determined based on the experimental data.
Single-mode vertical-cavity surface-emitting lasers (VCSELs) with intracavity contacts, composite distributed Bragg reflectors, and a rhomboidal selectively-oxidised current aperture are studied. It ...is shown that the use of a rhomboidal current aperture allows the light output polarisation to be fixed without using a special surface relief and leads to efficient narrowing of the emission line with retaining a high slope efficiency. The developed VCSELs have a high output power (exceeding 1 mW), a threshold current below 1 mA, an effective modulation frequency exceeding 5 GHz, and a linewidth smaller than 60 MHz at increased (65 - 75 °C) temperatures and are promising for application in compact Cs vapour cell atomic clocks.
We study the phenomenon of optical nonreciprocity in multilayer systems of magnetic nanoislands FeNi-Al2O3N. An anomalously large optical nonreciprocity was observed in these systems. The effect was ...manifested in nonequivalence of polarization plane rotation of reflected light for the sample in an initial position and rotated by . We assume that the super-vortex magnetization in the FeNi layers is responsible for the optical nonreciprocity effect. It was found that the value of nonreciprocity effect depends on the effective thickness of FeNi island layer and reaches a maximum with the super-vortex magnetization formation. The nonreciprocity magnitude is significantly higher than the values observed recently in systems of specially formed magnetic nanoparticles. Nonreciprocity magnitude is strongly dependent on interlayer interaction between nanoisland layers at large distances.
The development of heavy oil fields has been actively on the agenda. The problem arises due to the depletion of deposits with easily recoverable reserves, as well as due to the large reserves of ...shale oil and gas. Modern technology is gradually reaching an acceptable level of profitability. Many tasks remain to reduce environmental pressure on the environment. An important step in this direction was made with the introduction of electric fracturing technology. Technologies for isolating the mining zone are being developed. A variety of approaches are used to recover heavy oil. Use formation heating in various ways. Separate formation fluids into fractions in order to diversify recovery methods. Great prospects are opened using combined methods of exposure to kerogen. At the same time, many questions remain on methods for the further development of shale hydrocarbons. This is the development of norms and rules for the development of heavy oil. Coordination of actions of law-enforcement bodies and activity of technology developers is required. It is necessary to develop technological approaches that have shown their environmental effectiveness.
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