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Abstract—The paper presents the results of rock magnetic studies and relative paleointensity determinations from sediments of Lake Shira, Khakassia. Carrier minerals of natural remanent magnetization (NRM) were identified through hysteresis loop parameter measurements, thermomagnetic and X-ray diffraction (XRD) analyses. The sediment age was determined by radiocarbon dating; according to age estimates, the studied sediment sequence covers approximately the past 9100 years. To obtain high-quality relative paleointensity results, the determinations were made on linear segments of the pseudo-Arai‒Nagata diagrams. The quality was assessed by the criteria of the number of points in the calculations of slope, quality criterion (q), NRM fraction destroyed in the paleointensity determination interval, and relative paleointensity determination error (σ). According to the rock magnetic studies and XRD analysis, the magnetic carriers are mainly single-domain (SD) and pseudo-single-domain (PSD) magnetite and hematite. The comparison of the obtained relative paleointensity data with model paleointensities calculated for the Shira coordinates from the various models (CALS10K.1b (Korte et al., 2011), PFM9k.1 (Nilsson et al., 2014), HFM.OL1.AL1, CALS10k.2 ARCH10k.1 (Constable et al., 2016)), with absolute paleointensities and with the collection of results from the studies of sedimentary and igneous rocks and archaeomagnetic objects has shown that these data are in good agreement and share common trends. This provides grounds for applying this approach to paleointensity determination from bottom sediments of modern lakes using the pseudo-Thellier method. [ABSTRACT FROM AUTHOR]

The planishing of the surface of solids is aimed to minimize its roughness, downgrade a content of larger cracks in the modified layer, and, in general, reduce a thickness of the latter one. However, the abrasive processing induces residual stresses in the surface layer. The stresses relax through the motion of dislocations but in superhard materials like corundum or silicon dioxide, is extremely limited. In the present work, the role of the modified surface layer in corundum was studied within the context of the method and regime choice which affect the surface processing the mechanical characteristics of corundum. An efficiency of the abrasive treatment was assessed by comparison with the properties of surfaces processed with the ion polishing, sheared surface, and natural face of crystal from the viewpoint of reaching the high mechanical damage resistance of the surface. [ABSTRACT FROM AUTHOR]

Mathematical modeling is applied to study the electrothermal explosion conditions of a gasless system surrounded by a dielectric medium. It is shown how conductive heat exchange intensity and Joule heating power affect the formation of dimensionless temperature and concentration profiles, the integral depth of transformation, and the reaction front propagation velocity. The stages of ignition and reaction propagation are divided using a criterion that assumes a conversion depth of 0.99 at any point in the sample. The amount of product formed at the ignition stage is determined. It is demonstrated that a large transformation depth is achieved near critical conditions during ignition on the axis of the sample, thereby causing the displacement of the ignition zone from the axis to the surface of the sample. [ABSTRACT FROM AUTHOR]

Volcanic rocks, preserving paleorecords of Earth's magnetic field, are essential to constrain the working of the geodynamo, provided their primary signal was not biased. Using a thermomagnetometer, we simulate a situation where a sample's primary record, carried by a thermoremanence (TRM, acquired by cooling in air from 600°C to room temperature), is partly overprinted by a chemical remanence (CRM, acquired by 200 hr of isothermal exposure at 400°C). This situation leads to two directional and intensity components (in the form of linear segments) in the Zijderveld and Arai‐Nagata diagrams. In the case of unstable titanomagnetite grains prior to CRM acquisition, we show that both components can be strongly biased by up to ∼50° for paleodirections and ∼50% for paleointensities. In such a worst‐case scenario, the secondary CRM strongly overprints the primary TRM, rendering the common interpretation of Zijderveld and Arai‐Nagata diagrams in terms of characteristic components invalid. Plain Language Summary: Volcanic rocks, the magnetic minerals of which can acquire a thermoremanent magnetization (TRM) from Earth's magnetic field during their initial cooling, are essential to constrain the working of the geodynamo through Earth's history. However, if the rock is subsequently reheated at moderate temperature in another ambient field, the initial record can be partly overprinted by a chemical remanence (CRM). Starting from a TRM applied on materials of various thermostability, we reproduced in laboratory conditions the acquisition of a CRM by annealing the rock in a controlled ambient field for 200 hr at 400°C. Rock‐magnetic and structural analyses at regular intervals, supplemented by continuous measurements of the remanent magnetization, indicate the creation of new phases as a result of oxidation processes. The paleomagnetic analysis of the final products reveals the existence of two distinct components that can be associated with the initial TRM and the secondary CRM. Whereas the paleomagnetic record of the initial TRM is trustworthy for the most stabilized initial products, directional (up to 50°) and intensity (up to 50%) biases are observed for the least stabilized initial products, illustrating a critical example where the interpretation of characteristic components (linear segments in the interpretation diagrams) is invalid. Key Points: We overprint a thermoremanent magnetization (TRM) by cooling from 600°C with a chemical remanent magnetization by 200 hr exposure at 400°CChemical remanent magnetization was produced by the creation of cation‐deficient titanomagnetite phases, then stabilized by oxyexsolutionPaleodirections and intensities are strongly biased in the worst scenario, making the interpretation of characteristic components invalid [ABSTRACT FROM AUTHOR]

We consider a class of well-known high-order trinomial linear difference equations and analyze the non-asymptotic behavior of their solutions under non-zero initial conditions from the unit box. It is shown that, for certain subsets of coefficients in the stability domain, there always exist initial conditions leading to peak, a large deviation of solutions from the equilibrium position, and that these deviations may take arbitrarily large values. Various special cases are studied, numerical examples are presented. [ABSTRACT FROM AUTHOR]

It is shown that the results of dispersion of various materials in the mode of pulsed current action correspond to theoretical estimates of the wavelength of MHD instability. The sizes of the obtained metal grain, including refractory ones, correspond to the modes of exposure, and their microstructure corresponds to the conditions of formation. Modeling in the Comsol Multiphysics environment at a qualitative level revealed the influence of the thickness of the surface layer of the current flow on the dynamics of the formation and separation of liquid metal droplets. It is shown that one of the operating factors that create and increase instabilities is the heterogeneity of the distribution of Lorentz forces in the current supply zone. [ABSTRACT FROM AUTHOR]

Routes of modification of 5,6,7,8-tetrafluoro-3-methoxycarbonyl-2-(4-methoxyphenyl)-4H-chromen-4-one and its decarboxylated analogs in the reactions with aliphatic amines were studied and the biological activity of both the starting compounds and the products was tested. It was found that 5,6,7,8-tetrafluoro-3-methoxycarbonyl-2-(4-methoxyphenyl)-4H-chromen-4-one under the action of primary amines underwent the flavone-coumarin rearrangement through the addition of the amine at the C(2) atom. 7-Amino-substituted flavones were formed as by-products in the reactions with methyl- and benzylamines and as major products in the reactions with pyrrolidine. The process of nucleophilic aromatic substitution at the C(7) atom becomes a key one in the reactions of decarboxylated tetrafluoroflavones with primary amines and pyrrolidine. Mechanisms for the studied transformations were proposed. The starting tetrafluoroflavones were found to exhibit high antifungal activity, while antigonorrheal agents were revealed among the products of their transformations. [ABSTRACT FROM AUTHOR]

Praying mantises are the apex insect predators in many ecosystems, nevertheless they receive relatively less recognition in biodiversity reviews. We report a first survey of diversity of praying mantises in Cameroon, which is situated in the Congo Basin region, one of the richest biodiversity hotspots. Combination of light trapping with manual collecting resulted in 495 specimens representing 62 species. A total of eight species are novel for the country, at least five species are likely undescribed. DNA barcodes of 72 specimens representing every collected species were obtained, curated, and submitted to NCBI database. For eight species, barcodes are published for the first time. A maximum likelihood phylogenetic tree was created using all available barcodes of Mantodea of Central African subregion. The results obtained during this study stress the importance of combining traditional and molecular approaches during biodiversity assessments of often neglected taxa, the latter aiding in uncovering new species, resolving unknown morphological divergencies and assigning conspecifics. [ABSTRACT FROM AUTHOR]

We performed Monte Carlo simulations of single-wavelength lidar signals from multi-layered clouds with special attention focused on the multiple-scattering (MS) effect in regions of the cloud-free molecular atmosphere (i.e. between layers or outside a cloud system). Despite the fact that the strength of lidar signals from the molecular atmosphere is much lower compared to the in-cloud intervals, studies of MS effects in such regions are of interest from scientific and practical points of view. The MS effect on lidar signals always decreases with the increasing distance from the cloud far edge. The decrease is the direct consequence of the fact that the forward peak of particle phase functions is much larger than the receiver field of view (RFOV). Therefore, the photons scattered within the forward peak escape the sampling volume formed by the RFOV (i.e. the escape effect). We demonstrated that the escape effect is an inherent part of MS properties within the free atmosphere beyond the cloud far edge. In the cases of the ground-based lidar, the MS contribution is lower than 5 % within the regions of the cloud-free molecular atmosphere with a distance from the cloud far edge of about 1 km or higher. In the cases of the space-borne lidar, the rate of decrease of the MS contribution is so slow that the threshold of 5 % can hardly be reached. In addition, the effect of non-uniform beam filling is extremely strong. Therefore, practitioners should employ, with proper precautions, lidar data from regions below the cloud base when treating data of a space-borne lidar. In the case of two-layered cloud, the distance of 1 km is sufficiently large so that the scattered photons emerging from the first layer do not affect signals from the second layer when we are dealing with the ground-based lidar. In contrast, signals from the near edge of the second cloud layer are severely affected by the photons emerging from the first layer in the case of a space-borne lidar. We evaluated the Eloranta model (EM) in extreme conditions and showed its good performance in the cases of ground-based and space-borne lidars. At the same time, we revealed the shortcoming that can affect practical applications of the EM. Namely, values of the key parameters – i.e. the ratios of phase functions in the backscatter direction for the n th-order-scattered photon and a singly scattered photon – depend not only on the particle phase function but also on the distance from a lidar to the cloud and the receiver field of view. Those ratios vary within a quite large range, and the MS contribution to lidar signals can be largely overestimated or underestimated if erroneous values of the ratios are assigned to the EM. [ABSTRACT FROM AUTHOR]

We report a first example of field-induced (HDC = 2500 Oe) slow magnetization relaxation in the homotrinuclear linear heterospin manganese coordination compound with S = 7/2 ground state, based on the bidentate 3,5-di-tert-butyl-1,2-benzoquinone-1-monooxime (HL) ligand with composition {[MnL3]Mn[MnL3]}. [ABSTRACT FROM AUTHOR]

Titanium nickelide alloys have been prepared by pressure-assisted electrothermal explosion (ETE) synthesis. We have examined the effect of Joule heating power on ETE parameters and the physicomechanical properties of the synthesized alloys. The results demonstrate that raising the electrical voltage applied to the starting mixture leads to a decrease in ignition time and increase in the maximum ETE temperature. The ignition temperature was 350°C, independent of the Joule heating power. X-ray diffraction characterization showed that the major phase in the alloys was NiTi. According to uniaxial compression test results, the compressive strength of the alloys is 1980 MPa. Their microhardness HV is 6.4 ± 0.8 GPa. Instrumental indentation has been used to determine their hardness under load (HM = 9.4 GPa) and characteristics of their plastic and elastic deformation. The synthesized alloys have been shown to have high plasticity. [ABSTRACT FROM AUTHOR]

We study properties of the eigenvalues of the Laplace–Beltrami operator on L2 S d N - 1 , restricted to the class of antisymmetric functions. We prove that Vandermonde type determinants generate a basis for the space of antisymmetric homogeneous harmonic polynomials. Based on this fact, we calculate the multiplicity of each eigenvalue for d = 1 and present an algorithm for calculating eigenvalues for d ⩾ 2. [ABSTRACT FROM AUTHOR]

In semiconductors, exciton or charge carrier diffusivity is typically described as an inherent material property. Here, we show that the transport of excitons among CsPbBr3 perovskite nanocrystals (NCs) depends markedly on how recently those NCs were occupied by a previous exciton. Using transient photoluminescence microscopy, we observe a striking dependence of the apparent exciton diffusivity on excitation laser power that does not arise from nonlinear exciton-exciton interactions or thermal heating. We interpret our observations with a model in which excitons cause NCs to transition to a long-lived metastable configuration that markedly increases exciton transport. The exciton diffusivity observed here (>0.15 square centimeters per second) is considerably higher than that observed in other NC systems, revealing unusually strong excitonic coupling between NCs. The finding of a persistent enhancement in excitonic coupling may help explain other photophysical behaviors observed in CsPbBr3 NCs, such as superfluorescence, and inform the design of optoelectronic devices. [ABSTRACT FROM AUTHOR]

The article presents the results of a study of modern geodynamic movements in bottom structures of the White Sea (Baltic Shield). Based on expeditionary work in the White Sea, data were obtained on the formation of the seabed relief and thickness of unconsolidated sediments under the influence of modern seismotectonic events and geodynamic movements, as well as long-term neotectonic processes. It is shown that the Kandalaksha Bay depression is a modern graben developing along faults activated in the Quaternary. Graben development continues to the northwest, where a new Quaternary structure is being formed. Signs of modern geodynamic movements have been identified. The authors demonstrate the role of disjunctive tectonics in the formation of slopes and tectonic structures transverse to the strike of the bay, morphologically represented by relief ridges cutting the Sredny Ludy rise in Kandalaksha Bay. The influence of modern geodynamic processes on the distribution of thicknesses of Quaternary sediments of various genesis and the mosaic distribution of modern bottom sediments has been established. The influence of gravitational processes involved in the formation of underwater landslides, leading to the appearance of abnormally thick layers of the unconsolidated sedimentary cover, has been studied. [ABSTRACT FROM AUTHOR]

Abstract—Temporal characteristics of the localized damage development initiated by a short-time impact pointed loading of SiC ceramics which is widely applied as a protective material against the shock action upon engineering constructions and people were investigated. The statistics of crack nucleation and relaxation was studied with the methods of acoustic emission and electromagnetic emission, correspondingly. It was shown that the length of intervals between microcrack nucleations follows a power law specific to cooperative phenomena. The time distribution of decaying electric charges which appear on impact-induced crack edges and annihilate after the passage of impact wave was, in contrast, linear. The temporal pattern of the crack relaxation permitted identifying two sets of newly formed damages that are the tiny cracks localized in the grain bulk and those that interconnect grains. [ABSTRACT FROM AUTHOR]

The 17 km diameter, 30 Ma old Logoisk structure in Belarus (54°12′ N, 27°48′ E) was intensively drilled within the crater area. We summarize geological structure and petrologic information previously published mostly in Russian and describe shock deformation of zircon for the first time. The shock deformation features of zircon in the Logoisk suevite include the transition to reidite, the formation of planar fractures and granular textures, and the thermal decomposition to ZrO2 and SiO2. The presence of reidite in two grains in suevite was confirmed by micro‐Raman spectroscopy and EBSD (electron backscattered diffraction). Reidite was found in suevite glass of the Logoisk structure in grains containing zircon and in the ZrO2‐enriched rims on zircon. Granular zircon is commonly associated with ZrO2 and occurs as rims on zircon with interstitial impact melt, as dendritic rims, and in the inner parts of a zircon grain. A granular zircon from Logoisk represents the highest documented temperature of zircon transformation. The new data expands the knowledge of the P‐T conditions of formation of the Logoisk structure. [ABSTRACT FROM AUTHOR]

The mechanical fracture of silicon dioxide initiates the mechanoluminescence (ML) lighting due to multiple breakage of interatomic bonds with producing non-bridged oxygen groups of [≡Si–O–]. The detected ML signals consisted of series of pulses, the energy of which is proportional to the number of photons irradiated from the broken bonds. The comparative analysis of the energy distributions in ML series induced by the impact damage of the surface of crystalline and vitreous SiO2 before and after the Ar+-ion implantation was conducted. The interplay between random and correlated accumulation of broken bonds under the impact loading was found and discussed. [ABSTRACT FROM AUTHOR]

Abstract—A new approach to the solution of kinetic equations describing the process of formation of anhysteretic remanent magnetization (ARM) is proposed, which made it possible to accelerate the numerical calculation of the process of formation of ARM by two orders of magnitude for uniaxial oriented non-interacting single-domain particles, while practically not yielding in accuracy to a strict numerical solution. It follows from the calculation results that the susceptibility of ARM is entirely determined by the magnitude of the particle's coercivity parameter . The data of the previous approximate calculations of ARM value are compared with the exact results presented here and it is shown that the discrepancy between the exact data and the approximate estimates increases with the growth of g, but remains relatively small, within 23%. The proposed algorithm for the rapid calculation of kinetic equations allows us to analyze with physical rigor the method of pseudo-Thellier estimation of paleointensity for an ensemble of single-domain particles, which is supposed to be done in subsequent works. [ABSTRACT FROM AUTHOR]

In this work, a model is proposed to examine the role of viscoelasticity in the generation of simulated earthquake-like events. This model serves to investigate how nonlinear processes in the Earth's crust affect the triggering and decay patterns of earthquake sequences. These synthetic earthquake events are numerically simulated using a slider-block model containing viscoelastic standard linear solid (SLS) elements to reproduce the dynamics of an earthquake fault. The simulated system exhibits elements of self-organized criticality, and results in the generation of avalanches that behave similarly to naturally occurring seismic events. The model behavior is analyzed using the Epidemic-Type Aftershock Sequence (ETAS) model, which suitably represents the observed triggering and decay patterns; however, parameter estimates deviate from those resulting from natural aftershock sequences. Simulated aftershock sequences from this model are characterized by slightly larger p-values, indicating a faster-than-normal decay of aftershock rates within the system. The ETAS fit, along with realistic simulated frequency-size distributions, supports the inclusion of viscoelastic rheology to model the seismogenic fault dynamics. [ABSTRACT FROM AUTHOR]

Gold‐catalyzed interplay between ynamides and aminocarbonyls comprises a route to 2‐aminoquinolines. This modular annulation proceeds under relatively mild conditions (Ph3PAuCl/AgNTf2 5 mol %, DCE, 60–80 °C), and a number of functionalities were compatible (42 examples; 25–98% yields). In contrast to a group of other gold‐catalyzed methods employing the ynamide/amine combinations for the assembly of 2‐aminoquinolines, the developed approach utilizes a diversity of aminocarbonyl substrates and, in particular, allows a variation of the substituents in the 4th quinoline position. The synthetic potential of the obtained heterocyclic products was illustrated by post‐modifications of the quinoline backbone and the peripheral substituents. [ABSTRACT FROM AUTHOR]

Sufficient conditions for a trigonometric polynomial to be a refinement mask corresponding to a tight wavelet frame are obtained. The condition is formulated in terms of the roots of a mask. In particular, it is proved that any trigonometric polynomial can serve as a mask if its associated algebraic polynomial has only negative roots (of course at least one of them equals −1). [ABSTRACT FROM AUTHOR]

Motivated by recent experimental data on dichloro-tetrakis thiourea-nickel (DTN) [Soldatov et al., Phys. Rev. B 101, 104410 (2020)], a model of antiferromagnet on a tetragonal lattice with single-ion easy-plane anisotropy in the tilted external magnetic field is considered. Using the smallness of the in-plane field component, we analytically address field dependence of the energy gap in "acoustic" magnon mode and transverse uniform magnetic susceptibility in the ordered phase. It is shown that the former is non-monotonic due to quantum fluctuations, which was indeed observed experimentally. The latter is essentially dependent on the "optical" magnon rate of decay on two magnons. At magnetic fields close to the one which corresponds to the center of the ordered phase, it leads to experimentally observed dynamical diamagnetism phenomenon. [ABSTRACT FROM AUTHOR]

Recovering the geomagnetic field strength in the past is key to understanding deep Earth dynamics and detecting potential geodynamo regimes throughout the history of Earth. To better constrain the predictive power of the paleomagnetic record, we propose an approach based on the analysis of the dependency between geomagnetic field strength and inclination (angle made by the horizontal with the field lines). Based on the outcomes of statistical field models, we show that these two quantities should correlate for a wide range of Earth-like magnetic fields, even with enhanced secular variation, persistent nonzonal components, and severe noise contamination. Focusing on the paleomagnetic record, we show that the correlation is not significant for the Brunhes polarity chron, what we ascribe to inadequate spatiotemporal sampling. In contrast, the correlation is significant for the 1 to 130 Ma interval, whereas it only marginally succeeds prior to 130 Ma when strict filters on both paleointensities and paleodirections are applied. As we cannot detect significant variations in the strength of the correlation over the 1 to 130 Ma interval, we conclude that the Cretaceous Normal Superchron may not be associated with enhanced dipolarity of the geodynamo. The strong correlation obtained prior to 130 Ma when strict filters are applied indicates that the ancient field may not be on average so different from the present-day field. If long-term fluctuations nevertheless existed, detecting potential geodynamo regimes during the Precambrian is currently impeded by the sparsity of high-quality data passing strict filters in both paleointensities and paleodirections. [ABSTRACT FROM AUTHOR]

We performed Monte Carlo simulations of single-wavelength lidar signals from multi-layered clouds with special attention focused on multiple-scattering (MS) effect in regions of the cloud-free molecular atmosphere, i.e. between layers or 10 outside a cloud system. Despite the fact that the strength of lidar signals from molecular atmosphere is much lower compared to the in-cloud intervals, studies of MS effects in such regions are of interest from scientific and practical points of view. The MS effect on lidar signals is always decreasing with the increasing distance from the cloud far edge. The decreasing is the direct consequence of the fact that the forward peak of particles phase functions is much larger than the receiver field of view (RFOV). Therefore, the photons scattered within the forward peak escape the sampling volume formed by the RFOV, i.e. the 15 escape effect. We demonstrated that the escape effect is an inherent part of MS properties within the free atmosphere beyond the cloud far edge. In the cases of the ground-based lidar, the MS contribution is lower than 5% within the regions of the cloud-free molecular atmosphere having the distance from the cloud far edge about 1 km or higher. In the cases of the space-borne lidar, the decreasing rate of the MS contribution is so slow that the threshold of 5% can hardly be reached. In addition, the effect of non- 20 uniform beam filling is extremely strong. Therefore, practitioners should employ with proper precautions lidar data from regions below the cloud base when treating data of a space-borne lidar. In the case of two-layered cloud, the distance of 1 km is sufficiently large that the scattered photons emerging from the first layer do not affect signals from the second layer when we are dealing with the ground-based lidar. In contrast, signals from the near edge of the second cloud layer are severely affected by the photons emerging from the first layer in the case of a 25 space-borne lidar. We evaluated the Eloranta model (EM) in extreme conditions and showed its good performance in the cases of ground-based and space-borne lidars. At the same time, we revealed the shortcoming that can affect practical applications of the EM. Namely, values of the key parameters, i.e. the ratios of phase functions in the backscatter direction for the nth-order-scattered photon and a singly scattered photon depend not only on the particles phase function, but also on the distance from a lidar to the cloud 30 and the receiver field of view. Those ratios vary within a quite large range and the MS contribution to lidar signals can be largely overestimated or underestimated if erroneous values of the ratios are assigned to the EM. [ABSTRACT FROM AUTHOR]

The Ti x Zr 1-x C solid solutions were synthesized by electro-thermal explosion under pressure in the (Ti + Zr + C) blends mechanically activated in hexane (MA-ETE). The effect of mechanical activation (MA) duration on reaction blend characteristics, ETE parameters, phase composition, and microstructure formation in solid solutions was investigated. At MA, the Ti + Zr blend deforms metal crystal lattices for 20 min, complete amorphization occurs for 40 min, and the carbide grains form a cubic structure for 90 min. The single-phase Zr 0.50 Ti 0.50 C solid solution with a grain size of 3–5 μm and a submicron composite with a grain size of 0.1–0.2 μm containing the Ti 0.86 Zr 0.14 C and Zr 0.74 Ti 0.26 C solid solutions were synthesized in a one-stage process for the first time without any additional thermotreatment. The influence of mechanical activation on diffusional mass transfer of reactants, structure, and phase formation is discussed. [ABSTRACT FROM AUTHOR]

Effect of mechanical activation of components and external pressure on the combustion of a heterogeneous Ti + C mixture under SHS compaction is under study. It is shown that the presence of pressure (15 MPa) results in low-rate layered combustion (4–7 cm/s) and the absence of any external pressure causes unsteady combustion at a high burning rate (50–70 cm/s), namely surface-annular combustion and volumetric combustion, both based on convective heat and mass transfer. This paper proposes a mechanism for convective combustion at a high burning rate, based on the ignition of a heterogeneous mixture by a hot impurity gas released in a combustion wave and filtered through layered cracks and other macrodefects in the volume of charge compacts, which form during the pressing of powder mixtures. The mechanical activation of the reaction mixture components reduces the density and strength of the compacts and increases the efficiency of the formation of macrodefects. External pressure has the opposite effect as it prevents crack formation and the propagation of hot impurity gas through cracks. The consolidated samples of titanium carbide with a relative density of up to 95% are obtained in volumetric combustion. [ABSTRACT FROM AUTHOR]

Bezymianny volcano eruptions transport numerous xenoliths to the surface. Crustal xenoliths contain unique information about the crust structure and composition of crustal rocks located around the active magmatic system. We describe the chemical and mineral composition of upper crustal xenoliths that pyrometamorphosed (recrystallized and partially melted) in the Bezymianny shallow chamber. We reconstructed protoliths and hydrothermal processes for several rocks, which were previously altered, based on pre-pyrometamorhic relics (primary igneous associations in some xenoliths and rare hydrothermal relics). Moderate-K andesites, basaltic andesites, and basalts of Kamen and Bezymianny volcanoes dominate among the xenoliths. During pyrometamorphism, a microgranoblastic assemblage composed of homogenous pyroxenes, plagioclase, Fe-Ti oxides, and interstitial glass is formed in these xenoliths. Less common xenoliths are presented by high-K basaltic trachyandesite (plateau basalt from the basement of the Klyuchevskaya group of volcanoes). Quartz–carbonate–sulfide mineralization is present in some of them, which formed prior to xenolith entrapment and pyrometamorphism. When xenoliths were entrapped by magma, recrystallization of hydrothermally altered rock produced Fe-wollastonite–hedenbergite association (in some cases with garnet), untypical for Bezymianny. Some of these xenoliths have extremely high copper content (up to 1500 ppm). [ABSTRACT FROM AUTHOR]

Abstract—The evolution of the domain structure (DS) of cubic submicron- and micron-sized magnetite particles has been studied in detail during "cooling" of specimens from the Curie temperature Тс to room temperature Тr followed by their "reheating" to Тс in order to determine the degree of irreversibility of DS changes during heat treatment and their possible effects on the thermoremanent magnetization (TRM) properties. It is shown that typical magnetic configurations in particles up to 2 μm in size have flower or vortex shapes with one or two vortices. A model of the formation of thermoremanent magnetization (TRM) in submicron-sized pseudo-single-domain particles (PSD) is proposed based on an expansion of Neel's single-domain thermofluctuation model of TRM acquisition. According to the model, the equality of blocking and deblocking temperatures is retained for submicron PSD grains. Consequently, for this magnetic fraction, the Thellier laws of pTRM additivity and independence must also be valid. [ABSTRACT FROM AUTHOR]

The winter and spring varieties of peas (Pisum sativum) require careful study of the entire range of technological measures, including seeding rates, as the basis for optimal sowing density and the formation of phytocenose crops. This issue has not been resolved to date, not only in the context of agrobiological justification but also in everyday practice in Ukraine. This research was carried out in a field experiment in a three-way factorial experiment: factor "A" was the type of development - winter and spring; factor "B" was the variety - spring peas (Svit and Darunok Stepu) and winter peas (Moroz, Enduro and Baltrapp); and factor "C" was the seeding rate. According to the field studies, differences in the physiological and biochemical parameters of the P. sativum test culture characterised the photosynthetic activity of the plants, considering the type of development and variety. The winter varieties of P. sativum were characterised by a higher chlorophyll content (by 35-40%) compared to the spring varieties, which had an economic effect with an increase in the yield of dry biomass of the experimental crop and a decrease in seeding rates, with the formation and increase in grain yield by 14-18%. The intensity of chlorophyll in the process was not a determining factor in the accumulation of organic biomass. The extensive nature of the integration complex was noted (the amount of chlorophyll - the amount of biomass). At the optimal seeding rate, a certain specificity was observed in different types of P. sativum: for spring varieties, the sufficient rate was 0.9 million seeds/ha, and for winter varieties, it was 0.7 million seeds/ha. For varieties with a low productivity level (spring - Svit and winter - Moroz), the optimum sowing rate was around 0.7 million seeds/ha. The increase in the seeding rate was accompanied by a decrease in the content of various chlorophyll fractions from 10-12% to 20-26%. [ABSTRACT FROM AUTHOR]

A new method for the synthesis of benzofuro[3,2-d]pyrimidines was developed based on the oxidation of 2-(5-bromo-3,4-dihydropyrimidin-4-yl)phenols followed by the intramolecular nucleophilic aromatic substitution reaction. [ABSTRACT FROM AUTHOR]

The interaction of optically resonant semiconductor metasurfaces with intense, ultrashort laser pulses can be harnessed for enhancing and tailoring nonlinear frequency generation and ultrafast all-optical effects. Additionally, the dispersive nature of the metasurface response offers important opportunities to temporally shape the pulses themselves. Following a brief review of the state of the art of nonlinear, dispersive, and ultrafast semiconductor metasurfaces, this Perspective outlines possible future research directions and application opportunities for semiconductor metasurfaces operated in conjunction with ultrashort or shaped laser pulses. In particular, we speculate on possibilities for synthesizing arbitrary spatiotemporal light fields using specially designed metasurfaces as well as on potential application scenarios of the generated light fields. [ABSTRACT FROM AUTHOR]

A tunable polarization state converter/synthesizer based on an anisotropic resonant metasurface (ARM) is demonstrated. The semiconductor-based metasurface is designed to have a thermo-optically actuated optical mode excited by an incident free-space optical field. A diversity of output polarization states is reversibly generated and controlled by the temperature-dependent phase retardance between the two principal linear polarization states. The effect of metasurface inhomogeneity on the range of achievable polarization states is discussed and quantified, and the potential routes to "perfect" efficiency are suggested. By virtue of having a thickness of a fraction of the operating wavelength, ARMs represent a novel class of tunable polarization states' generating devices poised to find use in free-space communications and other applications. [ABSTRACT FROM AUTHOR]

Complete structural characterization of colloidal nanocrystals is challenging due to rapid variation in the electronic, vibrational, and elemental properties across the nanocrystal surface. While electron microscopy and X-ray scattering techniques can provide detailed information about the inorganic nanocrystal core, these techniques provide little information about the molecular ligands coating the nanocrystal surface. Moreover, because most models for scattering data are parametrically nonlinear, uncertainty estimates for parameters are challenging to formulate robustly. Here, using oleate-capped PbS quantum dots as a model system, we demonstrate the capability of small angle neutron scattering (SANS) in resolving core, ligand-shell, and solvent structure for well-dispersed nanocrystals using a single technique. SANS scattering data collected at eight separate solvent deuteration fractions were used to characterize the structure of the nanocrystals in reciprocal space. Molecular dynamics simulations were used to develop a coarse-grained form factor describing the scattering length density profile of ligand-stabilized nanocrystals in solution. We introduce an affine invariant Markov chain Monte Carlo method to efficiently perform nonlinear parameter estimation for the form factor describing such dilute solutions. This technique yields robust uncertainty estimates. This experimental design is broadly applicable across colloidal nanocrystal material systems including emergent perovskite nanocrystals, and the parameter estimation protocol significantly accelerates characterization and provides new insights into the atomic and molecular structure of colloidal nanomaterials. [ABSTRACT FROM AUTHOR]

References [[19], [21]] discuss some important features in this area for direction-of-arrival estimations, near-field microwave computational imaging, physics-driven intelligent autoencoder, and time-coding spoof surface plasmon polaritons. 10.1063/5.0132554 19 X. Q. Chen, L. Zhang, and T. J. Cui, " Intelligent autoencoder for space-time-coding digital metasurfaces", Appl. Phys. M. Sadafi, A. F. da Mota, and H. Mosallaei, " Dynamic control of light scattering in a single particle enabled by time modulation", Appl. Phys. [Extracted from the article]

Foot-and-mouth disease (FMD) has long been recognized as a highly contagious, transboundary disease of livestock incurring substantial losses and burdens to animal production and trade across Africa, the Middle East, and Asia. Due to the recent emergence of the O/ME-SA/Ind-2001 lineage globally contributing to the expansion of FMD, molecular epidemiological investigations help in tracing the evolution of foot-and-mouth disease virus (FMDV) across endemic and newly affected regions. In this work, our phylogenetic analysis reveals that the recent FMDV incursions in Russia, Mongolia, and Kazakhstan in 2021–2022 were due to the virus belonging to the O/ME-SA/Ind-2001e sublineage, belonging to the cluster from Cambodian FMDV isolates. The studied isolates varied by 1.0–4.0% at the VP1 nucleotide level. Vaccine matching tests indicated that the vaccination policy in the subregion should be tailored according to the peculiarities of the ongoing epidemiologic situation. The current vaccination should change from such vaccine strains as O1 Manisa (ME–SA), O no 2102/Zabaikalsky/2010 (O/ME-SA/Mya-98) (r1 = 0.05–0.28) to strains that most closely antigenically match the dominant lineage O No. 2212/Primorsky/2014 (O O/ME-SA//Mya-98) and O No. 2311/Zabaikalsky/2016 (O ME-SA/Ind-2001) (r1 = 0.66–1.0). [ABSTRACT FROM AUTHOR]

The statistics of record-breaking events plays an important role in the analysis of natural physical systems. It can provide an additional insight into the mechanisms and the occurrence of extreme events. In this work, the statistical aspects of the record-breaking events drawn from the Weibull distribution are considered and analyzed in detail. It is assumed that the underlying sequences of events are independent and identically distributed (i.i.d.). Several statistical measures of record-breaking events are analyzed. Exact analytical expressions are derived for the statistics of records. Particularly, the distributions of record magnitudes and the corresponding average magnitudes of records in case of Weibull distributed events are derived exactly for any specific record order and time step. In addition, a convolution operation is used to derive a recursive formula for the distribution of times of the occurrence of records. The analytical results are compared with the Monte Carlo simulations and their validity is confirmed. The numerical simulations also reveal that the finite-size effects strongly affect the statistics of records and need to be considered during the analysis of numerical experiments or empirical data. [ABSTRACT FROM AUTHOR]

Advancements in energy technologies created a new application for gas turbine generators, which are used to balance load. This usage also brought new challenges for maintenance because of harsh operating conditions that make turbines more susceptible to random failures. At the same time, reliability requirements for energy equipment are high. Reliability-centered maintenance based on forecasting the remaining useful life (RUL) of energy equipment, offers improvements to maintenance scheduling. It requires accurate forecasting methods to be effective. Defining stages in energy equipment operation allows for the improvement of quality of data used for training. At least two stages can be defined: normal operation and degradation process. A new method named Head move—Head move is proposed to robustly identify the degradation process by detecting its starting point. The method is based on two partially overlapping sliding windows moving from the start of operation to the end of life of the energy equipment and Kruskal-Wallis test to compare data within these windows. Using this data separation, a convolutional neural network-based forecasting model is applied for RUL prediction. The results demonstrate that the proposed degradation process identification (DPI) method doubles the accuracy when compared to the same forecasting model but without degradation process identification. [ABSTRACT FROM AUTHOR]

The possibility of functionalization of 2-(polyfluorophenyl)-4H-chromen-4-ones, with them having different numbers of fluorine atoms, with 1,2,4-triazole or imidazole under conditions of base-promoted nucleophilic aromatic substitution has been shown. A high selectivity of mono-substitution was found with the use of an azole (1.5 equiv.)/NaOBut(1.5 equiv.)/MeCN system. The structural features of fluorinated mono(azolyl)-substituted flavones in crystals were established using XRD analysis. The ability of penta- and tetrafluoroflavones to form persubstituted products with triazole under azole (6 equiv.)/NaOBut(6 equiv.)/DMF conditions was found in contrast to similar transformations with imidazole. On the basis of mono(azolyl)-containing polyfluoroflavones in reactions with triazole and pyrazole, polynuclear hybrid compounds containing various azole fragments were obtained. For poly(pyrazolyl)-substituted flavones, green emission in the solid state under UV-irradiation was found, and for some derivatives, weak fungistatic activity was found. [ABSTRACT FROM AUTHOR]

Microscale 3D structure realization nowadays is possible due to the direct laser writing (DLW)-photolithography. The DLW-photolithography technology provides a unique way to fabricate X-ray lenses with arbitrary shape and curvature radius less than 10 μm. However, an achievement of mechanically stable lithographic features is in demand for the fabrication of microoptical elements with high curvature values including X-ray lenses. According to this purpose, the research based on novel and promising methacrylate-containing material photocomposition for the DLW-photolithography is carried out. Improved solubility (1%wt) provides a large fabrication window, so it increases opportunities for use in the DLW-photolithography. A comprehensive study of the mechanical and morphological properties of the photocomposition makes it possible to determine the optimum DLW-photolithography parameters to fabricate mechanically-stable compound-refractive-lens (CRL) element. We use experimental methods of nanoindentation, confocal microscopy, and atomic force microscopy (AFM). The saturation value of reduced Young's modulus equal to 2.00±0.20 GPa is reached at a laser power of 5 mW and at a speed of 180 μm/s. [ABSTRACT FROM AUTHOR]

Balls-in-bins models describe a random sequential allocation of infinitely many balls into a finite number of bins. In these models a ball is placed into a bin with probability proportional to a given function (feedback function), which depends on the number of existing balls in the bin. Typically, the feedback function is the same for all bins (symmetric feedback), and there are no constraints on the number of balls in the bins. In this paper we study versions of BB models with two bins, in which the above assumptions are violated. In the first model of interest the feedback functions can depend on a bin (BB model with asymmetric feedback). In the case when both feedback functions are power law and superlinear, a single bin receives all but finitely many balls almost surely, and we study the probability that this happens for a given bin. In particular, under certain initial conditions we derive the normal approximation for this probability. This generalizes the result in Mitzenmacher et al. (2004) obtained in the case of the symmetric feedback. The main part of the paper concerns the BB model with asymmetric feedback evolving subject to certain constraints on the numbers of allocated balls. The model can be interpreted as a transient reflecting random walk in a curvilinear wedge, and we obtain a complete classification of its long term behavior. [ABSTRACT FROM AUTHOR]

An analysis of the first order transition kinetics between D0 3 and L1 2 phases in Fe 3 Ga-type alloy is carried out. Structure and magnetostriction of the samples were carefully controlled by SEM-EBSD analysis and magnetostriction tests after different heat treatments, and additionally in in situ regime by VSM and DSC. C-shaped curves for time-temperature-transition (TTT) diagram based on the results of the EBSD analysis of Fe-27Ga alloy are constructed in the temperature range between 400 and 550 °C. TTT diagram shows that the nucleation rate for L1 2 phase increases in the sequence 400 → 475 → 550 °C, while the growth rate reaches a maximum at about 500–525 °C. Effect of D0 3 ↔ L1 2 thermocycling on the kinetic of the D0 3 → L1 2 transition is studied for the first time. The amount of the L1 2 phase after sample re-quenching and subsequent annealing at the same annealing temperature and time, significantly increases compared with the first cycle quenching and subsequent annealing, demonstrating memory effect of previous transitions. [Display omitted] • TTT-diagram based on the results of the SEM-EBSD analysis of Fe-27Ga alloy are constructed. • Effect of D0 3 ↔ L1 2 thermocycling on the kinetic of the D0 3.→ L1 2 transition is studied. • Structure was controlled by SEM-EBSD, VSM, DSC, ND and magnetostriction method. [ABSTRACT FROM AUTHOR]

Microseismic source mechanisms in underground mines can provide information about the rock mass response to mining. Conventional approaches to such studies rely upon moment tensor solutions that are susceptible to modeling assumptions and need reliable information about source locations and high-resolution velocity models. We propose the application of unsupervised clustering to group microseismic events into different classes directly from the waveform data such that the events in a specific class have similar source mechanisms. Our method has three main steps, first using spectral decomposition to separate the source terms from the path-receiver contributions in the observed amplitude spectra of events occurring in spatially dense clusters. Second, reducing the number of features from the source spectra using independent component analysis (ICA). Third, applying a Gaussian mixture model (GMM) to the reduced feature matrix to obtain event clusters. To test our method, we generate synthetic waveform data using the receiver network and the recorded microseismic event locations in an underground potash mine in Saskatchewan. Results show the ability of our method to separate events into different classes corresponding to differences in source mechanisms. Application to field data recorded in the mine during February 2021 successfully discriminates between blasts and microseismic events. The data recorded between 1 March and 30 June 2021 that contain microseismic events only are divided into two dominant classes. Using known moment tensors (MT) of some of these events for labeling, we interpret one of the two classes as having dominant double-couple mechanisms as compared to the other which most likely corresponds to the linear dipole-tensile mechanisms. Our method, combined with some expert knowledge such as MT of some larger magnitude events, can offer an assessment of source types of large microseismic populations as often encountered in induced seismicity. • A clustering approach is developed to group microseismic events based on source mechanisms. • The developed method works directly on three-component (3C) waveform data. • It can separate blasts from microseismicity and group events based on source types. [ABSTRACT FROM AUTHOR]

The composition of the lipophilic components of the Rhodiola rosea L. plant was studied. Acidic and neutral components were identified by gas chromatography–mass spectrometry. With methyl-tert-butyl ether (MTBE) as an extractant instead of the volatile solvent diethyl ether, lipophilic extract was obtained. Methyl-tert-butyl ether used as an extraction solvent for raw materials has all the advantages of diethyl ether, being free of its disadvantages. It does not form peroxides or produce elevated partial gas pressure due to its higher boiling point. As a result, comparison with databases identified some triterpene, phenolic, and aliphatic acids with chain lengths 12 to 30 carbon atoms, including saturated, unsaturated, and dibasic acids. In addition to the components known from the literature, more than 50 triterpene and aliphatic compounds were detected in the unsaponifiable residue and acidic fractions for the first time. The hexane extract and the product obtained by the stepwise extraction by MTBE after the extraction of low-polarity compounds with hexane were investigated in a similar way. In the case of an extract obtained using MTBE after the extraction of low-polarity components with hexane, extraction of benzoic and cinnamic acids was more efficient compared to the exhaustive extraction of MTBE. These acids are absent from the hexane extract. Ethanol extraction was also carried out to test bioactivity: exhaustive and after hexane and MTBE extraction. Extracts obtained using MTBE and ethanol showed antiviral activity against the Ebola pseudovirus. [ABSTRACT FROM AUTHOR]

Unusual rearrangements were shown to accompany Brønsted acid-assisted peri-annulations of 1H-perimidines with 5-alkynylpyrimidines. These transformations take different routes depending on the nature of acetylene precursor, and lead to the formation of 7-formyl-1,3-diazopyrenes. [ABSTRACT FROM AUTHOR]

We have studied the effect of a small aluminum addition on the phase composition, microstructure, and physicomechanical characteristics of a Ti–B based metal–ceramic composite produced by self-propagating high-temperature synthesis compaction. The results demonstrate that the addition of 2 wt % aluminum increases the percentage of TiB2 and α-Ti in the structure of the composites. Evaluation of the unit-cell parameters of titanium by the Rietveld method (with Jana2006 software) has shown that co-alloying with oxygen and aluminum reduces the unit-cell volume of titanium and stabilizes α-Ti. The composites alloyed with Al have higher compressive strength and lower microhardness (HV) owing to the larger percentage of the Ti binder. [ABSTRACT FROM AUTHOR]

Abstract—The experiments have been carried out on the acquisition of thermochemical remanent magnetization (TCRM) in recent Kamchatka basalt containing grains of primarily magmatogene titanomagnetite (TM) with increased thermal stability by rapid heating of the initial samples in air to maximum temperatures of 500, 570 and 600°C followed by cooling at a rate of 1°C/h in the magnetic field of 50 μT. Thermal stability of single-phase oxidized TM fraction manifested itself in the appearance of a wide range of blocking temperatures from 270 to 540–570°C concentrated within two or three intervals of differently inclined linear segments on the Arai–Nagata diagrams. The integrated analysis of the results of this and our previous studies of TCRM acquisition in TMs has shown that when TCRM is created through the growth of the Curie temperature of the cells of TM oxy-exsolution structure as their composition approaches that of magnetite provided that their volume has been stabilized, TCRM proves to be close to the thermoremanent magnetization. This gives grounds to consider the paleointensity determinations obtained on these samples reliable. In other cases, the paleointensity determinations overestimate (for the low temperature segment (from 200 to 375–450°C) of the Arai-Nagata diagram) or underestimate the intensity of the magnetizing field. It is also concluded that the presence of a wide range of blocking temperatures may indicate thermochemical origin of remanent magnetization. [ABSTRACT FROM AUTHOR]