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The effectiveness and mechanism of the antioxidant action of a number of biologically active polysubstituted tetrahydroquinolines in a model reaction of liquid-phase oxidation of 1,4-dioxane have been studied. The research into the properties of these substances in the field of pharmacology is becoming increasingly important due to their ability to act as inhibitors of radical chain oxidation of organic compounds. The fact is that the manifestation of the antioxidant properties of biologically active compounds leads to an increase in the therapeutic effect of potential drugs. In this case, the drug, simultaneously with the function of treating the target disease, additionally slows down the rate of the undesirable process of lipid peroxidation of cell membranes. The oxidation reaction has been observed at 348 K using a manometric technique, measuring the change in the concentration of absorbed oxygen in the gas phase under different initial conditions of the studied antioxidants over time. In the presence of tetrahydroquinoline (THQ) additives, the kinetic curves of oxygen absorption exhibit an induction period (τ) when the rate of oxygen absorption is immeasurably low. The dependence of τ and the rate of inhibited oxidation on the concentration of THQ has been studied and the reaction mechanism formulated, including the stage of regeneration of the inhibitor at the stage of chain termination. Using the method of mathematical modeling, the adequacy of the mechanism to the obtained experimental data has been substantiated, the rate constants of the key stages and parameters of the efficiency of inhibitor fregeneration have been found. When comparing the results of this article with previously published data, it has been found that the mechanism and antioxidant efficiency of tetrahydroquinolines depend on their structure and the nature of the active site of inhibition.

Engineered metallic nanoparticles, which are found in numerous applications, are usually stabilized by organic ligands influencing their interfacial properties. We found that the ligands affect tremendously the electrochemical peak oxidation potentials of the nanoparticles. In this work, identical gold nanoparticles were ligand-exchanged and carefully analyzed to enable a precise and highly reproducible comparison. The peak potential difference between gold nanoparticles stabilized by various ligands, such as 2- and 4-mercaptobenzoic acid, can be as high as 71 mV, which is substantial in energetic terms. A detailed study supported by density functional theory (DFT) calculations aimed to determine the source of this interesting effect. The DFT simulations of the ligand adsorption modes on Au surfaces were used to calculate the redox potentials through the thermodynamic cycle method. The DFT results of the peak potential shift were in good agreement with the experimental results for a few ligands, but showed some discrepancy, which was attributed to kinetic effects. The kinetic rate constant of the oxidation of Au nanoparticles stabilized by 4-mercaptobenzoic acid was found to be twice as large as that of the Au nanoparticles stabilized by citrate, as calculated from Laviron’s theory and the Tafel equation. Finally, these findings could be applied to some novel applications such as determining the distribution of nanoparticle population in a dispersion as well as monitoring the ligand exchange between nanoparticles.

Fungi are among the most diverse and ecologically important kingdoms in life. However, the distributional ranges of fungi remain largely unknown as do the ecological mechanisms that shape their distributions1,2. To provide an integrated view of the spatial and seasonal dynamics of fungi, we implemented a globally distributed standardized aerial sampling of fungal spores3. The vast majority of operational taxonomic units were detected within only one climatic zone, and the spatiotemporal patterns of species richness and community composition were mostly explained by annual mean air temperature. Tropical regions hosted the highest fungal diversity except for lichenized, ericoid mycorrhizal and ectomycorrhizal fungi, which reached their peak diversity in temperate regions. The sensitivity in climatic responses was associated with phylogenetic relatedness, suggesting that large-scale distributions of some fungal groups are partially constrained by their ancestral niche. There was a strong phylogenetic signal in seasonal sensitivity, suggesting that some groups of fungi have retained their ancestral trait of sporulating for only a short period. Overall, our results show that the hyperdiverse kingdom of fungi follows globally highly predictable spatial and temporal dynamics, with seasonality in both species richness and community composition increasing with latitude. Our study reports patterns resembling those described for other major groups of organisms, thus making a major contribution to the long-standing debate on whether organisms with a microbial lifestyle follow the global biodiversity paradigms known for macroorganisms4,5.

Structural evolution, mechanical and tribological properties of an wrought Al–Mg alloy (AA5056) admixed with 5, 10 and 15 vol.% of iron powder using multi-pass friction stir processing (FSP) were studied. Homogeneous distribution of intermetallic compound (IMC) particles was achieved after 4 FSP passes that resulted in increasing the stir zone hardness and ultimate tensile stress with simultaneous loss in the ductility. The reinforcement of the aluminum alloy matrix with IMCs allowed reducing wear. Subsurface composite tribological layer was formed on the FSPed samples as a result of rubbing against a steel counterbody.

The paper presents a description of a new chemical method for the synthesis of magnetic nanoparticles of the intermetallic compound Nd2Fe14B, which consists of several stages. At the first stage, nanoparticles of neodymium oxide Nd2O3, iron oxide Fe2O3, and iron borate Fe3BO6were synthesised by chemical deposition methods. At the second stage, the powders were mixed in the required proportion and reduced using a two-stage diffusion-reduction process: first, at 800°C in an Ar + 5% H2medium, and then, to form the Nd2Fe14B phase, the powder mixture was added calcium hydride powder, the resulting mixture was pressed into a tablet, and at 800°C in an Ar medium, the calci-thermal reduction-diffusion synthesis was carried out. At the third stage, Nd2Fe14B nanopowders were separated from calcium oxide CaO by washing the resulting product with a solution of ammonium hydroxide and ethanol NH4Cl/C2H5OH. The phase composition, structure and morphology of the particles were determined by X-ray diffraction (XRD), scanning (SEM) and transmission (TEM) electron microscopy. Particle sizes were determined by dynamic light scattering (DLS). The composition of nanoparticles was determined using an energy dispersive X-ray spectrometer (EDS). XRD results indicate a high efficiency of the proposed method for the preparation of nanopowders of the intermetallic compound Nd2Fe14B.

The efficacy of aminoglycoside antibiotics is waning due to the acquisition of diverse resistance mechanisms by bacteria. Among the most prevalent are aminoglycoside acetyltransferases (AACs) that inactivate the antibiotics through acetyl coenzyme A-mediated modification. Most AACs are members of the GCN5 superfamily of acyltransferases which lack conserved active site residues that participate in catalysis. ApmA is the first reported AAC belonging to the left-handed β-helix superfamily. These enzymes are characterized by an essential active site histidine that acts as an active site base. Here we show that ApmA confers broad-spectrum aminoglycoside resistance with a molecular mechanism that diverges from other detoxifying left-handed β-helix superfamily enzymes and canonical GCN5 AACs. We find that the active site histidine plays different functions depending on the acetyl-accepting aminoglycoside substrate. This flexibility in the mechanism of a single enzyme underscores the plasticity of antibiotic resistance elements to co-opt protein catalysts in the evolution of drug detoxification.

The article assesses the development of the regional market for poultry products using the indicator of the development of the regional market. The purpose of the study is to determine the level of efficiency in managing the development of Ukrainian regional markets for poultry products based on the formation of a system of indicators of the level of development and assessment of their interdependence. The market development indicator is calculated as the sum of a weighted normalized assessment of each of the three components: the regional demand indicator, the regional supply indicator, and the trade development indicator in the region. The methodology for assessing the level of development of regional markets for poultry products includes: establishing indicators characterizing the level of development of regional markets for poultry products; assessment of the significance of characteristics in shaping the level of development of regional markets for poultry products; building a mathematical model for assessing the level of development of regional markets for poultry products. The calculations carried out using the proposed methodological approach make it possible to determine that the highest level of development of regional markets belongs to the central region.

Magnetar giant flares are rare explosive events releasing up to 1047erg in gamma rays in less than 1 second from young neutron stars with magnetic fields up to 1015−16G (refs. 1,2). Only three such flares have been seen from magnetars in our Galaxy3,4and in the Large Magellanic Cloud5in roughly 50 years. This small sample can be enlarged by the discovery of extragalactic events, as for a fraction of a second giant flares reach luminosities above 1046erg s−1, which makes them visible up to a few tens of megaparsecs. However, at these distances they are difficult to distinguish from short gamma-ray bursts (GRBs); much more distant and energetic (1050−53erg) events, originating in compact binary mergers6. A few short GRBs have been proposed7–11, with different amounts of confidence, as candidate giant magnetar flares in nearby galaxies. Here we report observations of GRB 231115A, positionally coincident with the starburst galaxy M82 (ref. 12). Its spectral properties, along with the length of the burst, the limits on its X-ray and optical counterparts obtained within a few hours, and the lack of a gravitational wave signal, unambiguously qualify this burst as a giant flare from a magnetar in M82.

In spite of the pervasive influence of propaganda and conspiracy theories in Russia, qualitative interviews demonstrate Russians' preference for first-hand, factual knowledge. In this article, we draw on the sociology of scientific knowledge to analyze this phenomenon. We conclude that the imperative to "be there" and "see with one's own eyes" is a discursive device that helps people avoid political polarization while reflecting and reinforcing depoliticization. [ABSTRACT FROM AUTHOR]

Electron beam additive manufacturing with simultaneously controlled feeding and melting of ER321 stainless steel and CuA19Mn2 bronze wires was carried out. The composite microstructure was formed consisting of homogeneously distributed ferrite and nickel-enriched bronze grains. Intensive intermixing and diffusion in the melted pool caused redistribution of nickel from stainless steel to the bronze and solidification of ferrite grains instead of the austenitic ones. Dispersion hardening of both ferrite and aluminum bronze grains occurred by core/shell β′/AlNi and AlFe3(κiv-phase) precipitates, respectively, that resulted in improving the ultimate tensile stress and increasing the microhardness of the composites depending upon the content of stainless steel introduced. Deformation was localized mainly in the bronze grains while ferrite grains retained their shape and were almost free of dislocations. The bronze grains allowed revealing only small regions containing the deformation microtwins. The tensile strength and microhardness of the composite samples were increased as compared to those of the pure bronze. No anisotropy was found during tensile testing.

New eco-friendly approaches were proposed for the synthesis of cis-cyclopentene-annulated heterocyclic compounds containing a tetrahydroquinoline moiety. For the first time we implemented a one-pot three-component cyclocondensation of aromatic amines (aniline, 5-aminoquinoline, o-phenylenediamine), aldehydes, and cyclopentadiene (CPD) in water and in the ionic liquid. The effect of synthesized substituted 3a,4,5,9b-tetrahydro-3H-cyclopenta[c]quinolines on the reproduction of house fly imago and on the initial stage of offspring ontogeny was evaluated in comparison with the effect of natural insect hormone using biological screening (Musca domestica). The most probable factors of stabilization of prepared compounds 7–10in the active site of the Heliothis virescensreceptor were identified using AutoDock 4.2, AutoDock Vina, and GOLD Suite molecular docking software. According to the results of three scoring functions, 4-(3-chlorophenyl)-8-fluoro-3a,4,5,9b-tetrahydro-3H-cyclopenta[c]quinoline forms the most stable complex with the chosen receptor. The results of bioassays and molecular docking indicate that these compounds may be considered as potential ecdysone agonists.

The components of the most common explosive ordnance in Eastern Europe have been analysed. The most dangerous explosive materials that rescuers may encounter when disposing explosive ordnance and clearing territories from mines have been identified. Such hazardous materials include tetryl, texogen, trinitrotoluolol, mercury fulminate, lead azide, lead trinitroresorcinate. An analysis of the chemical structure and physical and chemical properties of such materials has been carried out. It has been established that explosive materials can be divided into two classes with similar values based on such parameters as detonation velocity, volume of explosion products, and explosion heat. It has been established that the chemical structure of their molecules corresponds to the said two classes of physical and chemical properties. The first class includes materials based on hydrocarbons, the second includes materials based on heavy metals. It has been established that the specific volume values for the second class materials increase significantly, and exceed the indicators for the first class materials. This is due to the difference in the density of such materials by 2 to 4 times. The established features of the physical and chemical and explosive parameters of explosive materials can be used in the development of standard operating procedures and plans of actions of rescuers in order to increase the safety of handling the explosive ordnance.

Pure titanium composed of α single-phase has important applications for its excellent mechanical, physical, and chemical properties, which also impose high requirements on its surface finish. However, pure titanium is a difficult-to-machine material due to its low mass transportation caused by the low stiffness and the low thermal conductivity. Thus, it is greatly needed to investigate the machinability of pure titanium by precision grinding. In the present work, we carry out experimental and finite element simulation studies on the precision multi-grain grinding of pure titanium. Specifically, finite element model of pure titanium grinding using grinding wheel with multiple grains is established, which enables the prediction of successive material removal behavior by neighboring grains in line with experiments. The machining behavior of pure titanium and its correlation with machined surface morphology and grinding force are studied by experiment, and are further revealed by finite element simulation. Subsequent grinding experiments are performed to study the effects of workpiece speed and grinding depth on the ground surface quality of pure titanium, with which a surface roughness of 0.27 μm is obtained under the optimized grinding parameters.

The development of highly selective probes for nanoparticles is required due to their nanotoxicity. The latter strongly depends on the size, structure, and interfacial properties of the nanoparticles. Here, we demonstrate that a simple approach for the selective detection of Au nanoparticles that differ in their capping agent shows very high promise. Specifically, gold nanoparticles stabilized by each of the three different isomers of mercaptobenzoic acid (MBA) were imprinted in a soft matrix by adsorption of the nanoparticles, followed by filling the non-occupied areas through electropolyermization of an aryl diazonium salt (ADS). Nanocavities bearing the shape of the Au nanoparticles were formed upon the electrochemical dissolution of the nanoparticles, which were used for the reuptake of the Au nanoparticles stabilized by the different isomers. High reuptake selectivity was found where the originally imprinted nanoparticles were recognized better than the Au nanoparticles stabilized by other MBA isomers. Furthermore, an imprinted matrix by nanoparticles stabilized by 4-MBA could also recognize nanoparticles stabilized by 2-MBA, and vice versa. A detailed study using Raman spectroscopy and electrochemistry disclosed the organization of the capping isomers on the nanoparticles as well as the specific nanoparticle-matrix interactions that were responsible for the high reuptake selectivity observed. Specifically, the Raman band at ca. 910 cm–1for all AuNP–matrix systems implies the formation of a carboxylic acid dimer and thus the interaction of the ligands with the matrix. These results have implications for the selective and simple sensing of engineered nanoparticles.

Crystallization in confined spaces is a widespread process in nature that also has important implications for the stability and durability of many man-made materials. It has been reported that confinement can alter essential crystallization events, such as nucleation and growth and, thus, have an impact on crystal size, polymorphism, morphology, and stability. Therefore, the study of nucleation in confined spaces can help us understand similar events that occur in nature, such as biomineralization, design new methods to control crystallization, and expand our knowledge in the field of crystallography. Although the fundamental interest is clear, basic models at the laboratory scale are scarce mainly due to the difficulty in obtaining well-defined confined spaces allowing a simultaneous study of the mineralization process outside and inside the cavities. Herein, we have studied magnetite precipitation in the channels of cross-linked protein crystals (CLPCs) with different channel pore sizes, as a model of crystallization in confined spaces. Our results show that nucleation of an Fe-rich phase occurs inside the protein channels in all cases, but, by a combination of chemical and physical effects, the channel diameter of CLPCs exerted a precise control on the size and stability of those Fe-rich nanoparticles. The small diameters of protein channels restrain the growth of metastable intermediates to around 2 nm and stabilize them over time. At larger pore diameters, recrystallization of the Fe-rich precursors into more stable phases was observed. This study highlights the impact that crystallization in confined spaces can have on the physicochemical properties of the resulting crystals and shows that CLPCs can be interesting substrates to study this process.

Florida has been about as active as it gets with respect to sales tax litigation over the last few years. In 2017, there have been a few noteworthy cases. Both [...]

At the present time, the electrodeposition of chromium metal coatings of sufficient thickness and quality is possible only from chromium plating electrolytes containing chromic acid. The authors investigated the effect of the composition of chromium plating electrolyte on the quality of the resulting metal coating. It has been demonstrated that the introduction of organic additives, of gallic acid in particular, leads to significant changes in the surface of the metal deposit and to a decrease in its hardness. Assumptions have been made about the influence of organic additives on the metal deposition process. The experimental data on the content of gases in the chromium deposits obtained from electrolytes with gallic acid additive and without it have been presented.

Cynanchum viminalesubsp. australe, more commonly known as caustic vine, is a leafless succulent that grows in the northern arid zone of Australia. Toxicity toward livestock has been reported for this species, along with use in traditional medicine and its potential anticancer activity. Disclosed herein are novel seco-pregnane aglycones cynavimigenin A (5) and cynaviminoside A (6), together with new pregnane glycosides cynaviminoside B (7) and cynavimigenin B (8). Cynavimigenin B (8) contains an unprecedented 7-oxobicyclo[2.2.1]heptane moiety in the seco-pregnane series, likely arising from a pinacol-type rearrangement. Interestingly, these isolates displayed only limited cytotoxicity in cancer and normal human cell lines, in addition to low activity against acetylcholinesterase and Sarcoptes scabieibioassays, suggesting that 5–8are not associated with the reported toxicity of this plant species.

•The administration of mesenchymal stromal cells (MSCs) exerts a positive effect on restoration of T cell subpopulations and recovery of immune system of patients after allogeneic hematopoietic stem cell transplantation.•Three days after MSC injection, the numbers of CD8+ effector cells (CD8+TE, CD8+TM, and CD8+EM) increased significantly.•Faster recovery of the CD4+ cell population was observed in patients at 30 days after MSC infusion compared to patients without MSC infusion.•The concentrations of proinflammatory and anti-inflammatory cytokines IL-6, IL-8, IL-17, TNF-α, and IFN-γ, were increased significantly in patients injected with MSCs.

Strigolactones (SLs) regulate many aspects of plant development, but ambiguities remain about how this hormone is perceived because SL-complexed receptor structures do not exist. We find that when SL binds the Strigareceptor, ShHTL5, a series of conformational changes relative to the unbound state occur, but these events are not sufficient for signalling. Ligand-complexed receptors, however, form internal tunnels that posit an explanation for how SL exits its receptor after hydrolysis.

Electrically detected magnetic resonance (EDMR) is an effective spectroscopic method used for characterizing semiconductive solid-state materials. High spin sensitivity and the capability to explore spin-dependent transport mechanisms, which are crucial for the development of semiconductor devices, define it from other methods based on magnetic resonance. High frequency and high magnetic field EDMR implementation was motivated by the necessity to obtain access to more precise, high-resolution data to enhance the method’s research potential. We present an EDMR system based on a unique THz FraScan spectrometer, which performs frequency sweeps ranging from 80 GHz to 1.1 THz, and the magnetic field sweeps up to 16 T. The study addresses the instrumentation, detection scheme, and 85–328.84-GHz EDMR results on highly nitrogen-doped 15R SiC monocrystals. Furthermore, the results demonstrate a subjective advantage of frequency-domain EDMR (FD EDMR) over conventional magnetic field domain measurements in terms of substantially greater signal-to-noise ratio (SNR) and the ability to record an EDMR frequency-field map (EDMR FFM).

Recruitment of representative and generalizable adult samples is a major challenge for researchers conducting economic field experiments. Limited access to representative samples or the high cost of obtaining them often leads to the recruitment of non-representative convenience samples. This research compares the findings from two field experiments involving 860 adults: one from a non-representative in-person convenience sample and one from a representative online counterpart. We find no meaningful differences in the key behaviors of interest between the two samples. These findings contribute to a growing body of literature demonstrating that non-representative convenience samples can be sufficient in certain contexts.

Graphical Abstract:

Purpose: This study aims to create a new tool for fast computer simulations allowing one to design advanced electromagnetic calorimeters with the required properties. The application must calculate the calorimeter efficiency and measure the particles' energies, momenta and interaction time to detect the particles. This application should become the basis for a new technology of positron emission tomography. Methods: To solve the problem, a new C++ application based on Geant4 simulation toolkit has been developed. To monitor the response of calorimeters to different types of primary particles, we used different auxiliary Geant4 classes. In addition, we compare the simulation results for the detectors of three different setups, taking into account the detection of both electrons and gamma-quanta, and analyze their efficiency. To evaluate the capability of calorimeters to work under radiation load, we use an experimentally measured transmission function of radiation-damaged PbF2. Results: Three calorimeter setups exploiting PbF2were simulated with a new C++ application based on Geant4. We showed that such type of calorimeter has an energy resolution of \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${{4.1\% } \mathord{\left/ {\vphantom {{4.1\% } {\sqrt {E_{{e^{ + } }} [{\text{GeV}}]} }}} \right. \kern-0pt} {\sqrt {E_{{e^{ + } }} [{\text{GeV}}]} }}$$\end{document}and good linearity of response for GeV positrons measurements. The efficiency of such structures is found to be approximately 20% for gamma photons’ detection. The multilayered structure based on gamma-quanta detection has been proven to be more efficient. It was shown that for the total ionizing dose of 30 krad the Cherenkov light yield decreases by up to two times for 14 cm long PbF2crystals, while for the shorter ones (2.5 and 1.5 cm) this effect is almost negligible. Conclusions: We present a new user application in Geant4 for fast simulation of complex structures designed for detection of different high-energy neutral and charged particles. Simulation of calorimeter interaction with 103of 3 GeV positrons takes 20 min on usual laptop, while for 105511 keV gamma photons it takes 1 min on average. This application allows one to evaluate the efficiency of electromagnetic calorimeters exploiting lead fluoride crystals. Our results pave the way for advanced particle energy measurements, including those used in rapidly developing medical applications such as positron emission tomography, single-photon emission computed tomography etc.

Abstract: This paper describes the results of calculations using the density functional method to determine the parameters governing charge transfer rates in stacks composed of “donor (D)–π-bridge–acceptor (A)–π-bridge–donor (D)” molecules. The Marcus theory is employed to calculate the reorganization energy, which is a property of individual molecules, and the charge transfer integral, which is calculated for molecular dimers. Another important structural property of the molecules is the side substituent of the acceptor block, that is, short linear or branched alkyl chains. These can influence the reorganization energy values and the morphology of the film, which, in turn, impacts the charge transfer integral. Finally, the Einstein–Smoluchowski formula is used to determine the electron and hole mobility for transport along the stacking direction. The calculated values are then compared to experimental data found in the literature for polymers with similar monomer units that only differ in the length of their acceptor block substituent.

The effects of magnon dissipation on the properties of magnetoelastic waves in ferromagnets in the vicinity of magnetoelastic resonance are investigated. The magnetoelastic waves in this region are strongly anisotropic, and the directions with high intensity (caustic waves) are formed. Dissipation leads to the disappearance of the gap between different magnetoelastic modes, finiteness of amplification factor, and to the damping of caustic waves in some directions. The caustic patterns formed by the caustic waves are transformed due to dissipation. In elastically isotropic and slightly anisotropic ferromagnets, caustics disappear when even a small dissipation is taken into account, while in strongly elastically anisotropic ferromagnets the main features of caustic patterns are retained in a wide region of the external magnetic field.

Exfoliative cheilitis is misdiagnosed due to the similarity of clinical manifestations with other cheilitis. The disease lasts for years.

Most of the light from blazars, active galactic nuclei with jets of magnetized plasma that point nearly along the line of sight, is produced by high-energy particles, up to around 1 TeV. Although the jets are known to be ultimately powered by a supermassive black hole, how the particles are accelerated to such high energies has been an unanswered question. The process must be related to the magnetic field, which can be probed by observations of the polarization of light from the jets. Measurements of the radio to optical polarization—the only range available until now—probe extended regions of the jet containing particles that left the acceleration site days to years earlier1–3, and hence do not directly explore the acceleration mechanism, as could X-ray measurements. Here we report the detection of X-ray polarization from the blazar Markarian 501 (Mrk 501). We measure an X-ray linear polarization degree ΠXof around 10%, which is a factor of around 2 higher than the value at optical wavelengths, with a polarization angle parallel to the radio jet. This points to a shock front as the source of particle acceleration and also implies that the plasma becomes increasingly turbulent with distance from the shock.

Newly formed territorial communities acquire a real subjectivity in the processes of the management of territorial development: they become responsible for a significant share of day-to-day economic activities within their sphere of responsibility, especially in territories with a predominantly rural population. This article aimed to study the changing role of local self-government in ensuring the economic development of the low-urbanized territory, determining public opinion and expectations of residents from local governments in the new conditions. A public opinion poll of residents living in selected local communities was conducted. This article identified the objective factors of the level and pace of newly formed territorial communities’ development in Ukraine. It has been proved that the decentralization of power changes the role of local government and the expectations of residents from it and their assessments of the situation at the local level.

Blazars are active galactic nuclei (AGN) with relativistic jets whose non-thermal radiation is extremely variable on various timescales1–3. This variability seems mostly random, although some quasi-periodic oscillations (QPOs), implying systematic processes, have been reported in blazars and other AGN. QPOs with timescales of days or hours are especially rare4in AGN and their nature is highly debated, explained by emitting plasma moving helically inside the jet5, plasma instabilities6,7or orbital motion in an accretion disc7,8. Here we report results of intense optical and γ-ray flux monitoring of BL Lacertae (BL Lac) during a dramatic outburst in 2020 (ref. 9). BL Lac, the prototype of a subclass of blazars10, is powered by a 1.7 × 108MSun(ref. 11) black hole in an elliptical galaxy (distance = 313 megaparsecs (ref. 12)). Our observations show QPOs of optical flux and linear polarization, and γ-ray flux, with cycles as short as approximately 13 h during the highest state of the outburst. The QPO properties match the expectations of current-driven kink instabilities6near a recollimation shock about 5 parsecs (pc) from the black hole in the wake of an apparent superluminal feature moving down the jet. Such a kink is apparent in a microwave Very Long Baseline Array (VLBA) image.

The technique for determination of zero-strength temperature, [T.sub.z.s] and zeroductility temperature, [T.sub.z.d], is developed and tested with the goal of evaluation of processes, which take place in dispersion-strengthened nickel alloys and in the welded joints of these alloys at temperatures close to the melting temperature point [T.sub.L]. Analysis of changes in tensile strength, [σ.sub.B], at temperatures close to [T.sub.L] shows the presence of an inflection on the strength curve for alloys with both monocrystalline and polycrystalline structures. The temperature of this inflection coincides with the temperature of the sharp fali of relative reduction in area, to almost zero which indicates the start of melting of cast metal. These suppositions are confirmed by fractographic and metallographic investigations of the structure and fracture surface., 1. Introduction Knowledge of the special features of the variation of the properties of metals at elevated temperatures expands the possibilities of improving their weld-ability and can be used to [...]

The article explores the problem of alternative navigation support for high-precision weapons that use guidance based on signals from global navigation systems. It proposes the use of an autonomous navigation system replacing satellite navigation in the case where major Global Positioning System-like systems are unavailable. It suggests the idea and the model of a moving navigation field that can move along the weapon trajectory. The model of accuracy for the pseudolite navigation system uses the least squares method as its basis. The study looks into the accuracy parameters of the moving navigation field. The results of the study show the advantages of a moving field when compared with a stationary navigation field in case of autonomous use. This research also shows the possibility of using an autonomous system for Special Forces, search and rescue operations, and robotic and unmanned aerial, ground, and sea-based vehicles.

Introduction: Akt activation is involved in the pathogenesis of inherited thyroid cancer in Cowden's syndrome and in sporadic thyroid cancers. In cell culture, Akt regulates thyroid cell growth and survival; [...]