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Using adiabatic point-particle black hole perturbation theory, we simulate plausible gravitational wave (GW) signatures in two exotic scenarios (i) where a small black hole is emitted by a larger one ('black hole emission') and (ii) where a small black hole is emitted by a larger one and subsequently absorbed back ('black hole absorption'). While such scenarios are forbidden in general relativity (GR), alternative theories (such as certain quantum gravity scenarios obeying the weak gravity conjecture, white holes, and Hawking radiation) may allow them. By leveraging the phenomenology of black hole emission and absorption signals, we introduce straightforward modifications to existing gravitational waveform models to mimic gravitational radiation associated with these exotic events. We anticipate that these (incomplete but) initial simulations, coupled with the adjusted waveform models, will aid in the development of null tests for GR using GWs. [ABSTRACT FROM AUTHOR]

Egyptians of the predynastic era had a good decimal number system for counting and addition. Although, up to some times, they had problem in counting beyond a million, by the dawn of their history, Narmer, the founder of the first Egyptian dynasty had accountants that could record 400,000 cows and 1,422,000 goats of a war booty. Except for some ambiguities in the case of Mayan number system, specialists in the history of mathematics can guess that how the counting system of the various civilizations evolved into one of the number systems in base 10, 20, 60, etc. There is a puzzle in the mixture of the Egyptian decimal and binary number systems which we are going to discuss and present a justification for it. The novelty of the present paper is the study of the evolution of the binary number system from the predynastic Egypt down to the Leibniz era who, by the benefit of Khwarazmi's "Indian Arithmetics," completed this evolution by representing integers in $0-1$ forms and performing the hybrid decimal/binary Egyptian arithmetic operations purely inside the $0-1$ system. The second author is pleased to dedicate his share of this paper to Esfandiar Eslami showing his love and appreciation for decades of his friendship and collaboration (since 1967) and, of course, the young coauthor joins the joy of this dedication to her former professor.

Copyright of Journal of Mahani Mathematical Research Center is the property of Shahid Bahonar University of Kerman, Department of Pure Mathematics and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This study presents an evaluation of the liquid-liquid equilibria (LLE) for both binary and ternary systems involving methanol, cyclohexane, and n-hexane at a pressure of 1 MPa. The investigation encompasses a comprehensive analysis of phase behavior, including thermodynamic modeling, and graphical representations. The binary system of methanol and cyclohexane is examined extensively to understand their phase equilibrium at varying temperatures, with a focus on the T-xx diagram, activity coefficient calculations, and vapor-liquid equilibrium (VLE) analyses. Furthermore, the ternary system incorporating n-hexane alongside methanol and cyclohexane is investigated to explore the intricacies of multicomponent phase behavior. Through the utilization of thermodynamic models such as the Non-Random Two-Liquid (NRTL) model and Universal Quasi-Chemical (UNIQUAC) model, key insights into the phase compositions, distribution coefficients, azeotropes, and residue curves are elucidated. The findings from this study provide valuable insights into the thermodynamic interactions within these systems, offering essential guidance for process design and optimization in various industrial applications.

High-resolution optical spectra of the B[e] star CI Cam were obtained on arbitrary dates 2002–2023 using the 6-meter BTA telescope with the echelle spectrograph NES. The variability over time of the powerful emissions of Hα and He I profiles is found. For two-peak emissions with "rectangular" profiles, the intensity ratio of blue-shifted and red-shifted peaks is , except one date. A decrease in the intensity of all double-peaked emissions with "rectangular" profiles was revealed as they moved away in time from the 1998 outburst. The average radial velocity for emissions of this type for all observation dates varies in the range km/s. The half-amplitude of the change (standard deviation) is equal to km/s. The velocity for single-peaked ion emissions (Si III, Al III, Fe III) differs little from the values of , but the measurement accuracy for these emissions is worse: the average error for different dates ranges from 0.4 to 1.3 km/s. The systemic velocity is assumed to be km/s according to the stable position of the forbidden emission [N II] 5755 Å. The position of single-peak emissions [O III] 4959 and 5007 Å is also stable: km/s. Emissions [O I] 5577, 6300, 6363 Å, [Ca II] 7291 and 7324 Å are absent from the spectra. Appearance of the emission near 4686 Å is an infrequent event, its intensity rarely exceeds the noise level. Only a wide asymmetric emission with an intensity of about 16% above the continuum was registered in the spectrum for September 3, 2015. Questions arise about the use of this emission to estimate the period of variability of the star and about localization of this feature in the CI Cam system. The photospheric absorptions of N II, S II, and Fe III with a variable position are identified. [ABSTRACT FROM AUTHOR]

Knowledge of adsorption isotherms is essential for the design and optimization of chromatographic separation processes. Since the experimental determination of these thermodynamic functions is a complicated and time consuming task, there is a need to develop methods which are fast and easy to apply. An attractive group of methods is based on neglecting in the analysis of measured dynamic elution profiles all kinetic effects. These methods assume the validity of an isotherm model equation and exploit the possibility to solve analytically the column mass balance equations of the equilibrium model. If just the dispersive part of an elution profile is, the method is known as "elution by characteristic point" (ECP). The ECP method has been applied successfully to analyse column effluent profiles of single component dissolved in a mobile phase. This work extends the ECP method to analyse just the shapes of elution profiles recorded after injecting samples that contain two key components to be separated. The extended ECP method requires recording only one overloaded elution profile for the two-component mixture and offers a fast and efficient way to estimate isotherm model parameters. The method is in particular attractive if there is limited access to the pure components, as for example in cases of enantiomers. The underlying theory is presented and applied for the case that the adsorption equilibria can be described satisfactorily by the classical competitive Langmuir model. Core of the theory are the available analytical equations describing the outlet concentration profiles of the two solutes for the equilibrium controlled case the. Considering a case study, it is shown that the extended ECP method can be applied successfully for columns characterized by 2500 or more theoretical plates. However, the method can be useful also for columns with lower efficiency. It provides then a rough estimation regarding the isotherm courses. [ABSTRACT FROM AUTHOR]

In this study, the solvatochromic behavior of Methyl orange was studied visible spectrophotometrically in seven aqueous binary systems from water with methanol, ethanol, propanol, DMF, DMSO, acetone and dioxane solvents. The spectral data was interpreted in terms of solute-solvent and solvent-solvent interactions. The deviation from linearity in the plots of νmax versus x2 due to preferential solvation of the Methyl orange by one component of the mixed solvent and due to solvent microheterogeneity. The preferential solvation parameters local mole fraction X2L, solvation index δs2 and exchange constant K12 were evaluated. The preference of solute to be solvated by one of the solvating species relative to others was explained. All values of K12 were less than unity that indicates the preferential solvation of Methyl orange by water, except in case the water-propanol mixture where K12 was higher than unity. The preferential solvation index δs2 values were calculated and interpreted for each binary mixture. The magnitude of preferential solvation index was highest in water-DMSO mixtures than in the all other solvent mixtures. The energy of electronic transition in maximum absorption (ET) was calculated in each binary mixture. The extent and importance of each solute-solvent interactions to ET were analyzed by the linear solvation energy relationships using the Kamlet-Taft strategy. [ABSTRACT FROM AUTHOR]

We investigate unresolved binary systems with components of main sequence star (MS) and white dwarf (WD) in nine open clusters. These systems are located below and to the left of the main sequence on the color-magnitude diagram. We compare the number of cluster stars that have likely evolved into white dwarfs with the number of candidates for unresolved binary systems with WD. The number of probable cluster members lying below the main sequence, is generally less than the expected number of WDs. The observations in the ultraviolet could detect WDs and unresolved binary WD+MS systems more confidently than the observations in the visible range. [ABSTRACT FROM AUTHOR]

This work provides, at lower order, general analytical solutions for the orbital separation, merging time, and orbital frequency of binary systems emitting gravitational waves while being submitted to mass variations. Specific features, depending on the exponent of the mass derivative, are investigated in details. Two phenomenologically interesting cases are explicitly considered: (i) binaries formed by two light primordial black holes submitted to Hawking evaporation and (ii) bodies driven by a Bondi accretion of phantom dark energy. It is shown that three different regimes arise, including an intricate non-monotonic behaviour of the system. We study subtle imprints that could be associated with those phenomena. A careful analysis of the conditions of validity of the different hypotheses performed is finally carried out. [ABSTRACT FROM AUTHOR]

We present X-ray and spectropolarimetric observations of the WN+O binaries WR71 and WR97, which are analogs of the well-studied V444 Cygni. The combined results have the potential to constrain the locations and properties of wind interaction regions in these binaries, give clues to their subsequent evolution, and address the commonalities among WR+O systems. [ABSTRACT FROM AUTHOR]

The γ-ray source 4FGL J2054.2+6904 discovered with Fermi was recently classified as a pulsar candidate. Its possible X-ray and optical counterpart was identified with Swift. Using Zwicky survey data we show that the counterpart is variable in the optical with the period of about 7.5 h. The shape of the light curve is almost sinusoidal with the amplitude of ≈0.5m. The spectral energy distribution corresponds to the stellar spectrum with the effective temperature of 5820 ± 410 K. We also firmly detected the source in X-rays using the SRG/eROSITA all sky survey data. Its X-ray spectrum can be described by a power law with the photon index of about 1.0 and unabsorbed flux ≈2 × 10–13 erg/(s cm2) in the 0.5–10 keV range. These results show that 4FGL J2054.2+6904 is a promising candidate to a millisecond pulsar in a close binary system of the "redback" type. [ABSTRACT FROM AUTHOR]

High salinity has been a major challenge in oil recovery. Here, two binary systems composed of sodium fatty alcohol polyoxyethylene ether carboxylate (AECM) and cationic surfactants, cetyltrimethylammonium bromide (CTAB) and cetylpyridinium chloride (CPyCl) were developed. Their fundamental properties; namely, oil/water interfacial tension, wettability, emulsification, adsorption, and oil‐washing were investigated and compared. The results showed that both AECM–CTAB (4:6–7:3, m/m) and AECM–CPyCl (5:5–6:4, m/m) could decrease oil/water interfacial tension below 10−2 mN/m. Even the total salinity was close to 200,000 mg/L after 7 days of quartz sand adsorption, showing a good interfacial activity and excellent anti‐adsorption properties. All these compound drives could effectively change the wettability of the glass surface, which reduced the contact angle to a minimum of 54.76°. In addition, the emulsification time could reach up to 24 h at 85°C, with excellent emulsification performance at high temperatures. The oil washing efficiency could reach 74.68% after 48 h. According to our comprehensive analysis, the best formulation was obtained at AECM/CTAB ratio of 5:5. [ABSTRACT FROM AUTHOR]

In this study, orange peel (OP) biochar was used as a bio-sorbent for the removal of copper and lead from wastewater in single and binary systems. The equilibrium and kinetic studies were conducted at a pH value of 5, which was the maximum adsorption pH value for both metal ions. The equilibrium studies were investigated at a varying initial concentration (10–200 mg/L) with a constant dosage of 0.1 g, while the kinetic studies were conducted at a fixed initial concentration of 200 mg/L with a constant dosage of 1 g/L for both single and binary systems. The maximum adsorption capacity of the orange peel biochar was 28.06 mg/g, 26.83 mg/g, 30.12 mg/g and 27.71 mg/g for single Cu2+, binary Cu2+, single Pb2+ and binary Pb2+ systems, respectively. The Langmuir isotherm model fitted the experimental data, suggesting that adsorption occurred on a monolayer, while the pseudo-second-order model performed well with the kinetic data. The point of zero charge (pHpzc) of the orange peel biochar was found to be 10.03, which revealed that the surface of the bio-sorbent contains basic groups. A Fourier infrared transform (FTIR) spectroscope and scanning electron microscope, coupled with energy dispersive x-ray (SEM-EDX) and x-ray diffraction analyses, were used to determine the functional groups, surface morphology, and inorganic elements present on the surface of the bio-sorbent, respectively. The results obtained have shown that orange peel biochar is efficient for the removal of Cu2+ and Pb2+ ions from an aqueous solution. [ABSTRACT FROM AUTHOR]

The paper analyses whether the type of institution from which students graduate has an impact on their unemployment propensity. It uses official data on the Portuguese higher education system, for 2018, at the program/institution level, which provides information on graduate unemployment, as well as demographic and socioeconomic background information. A fractional probit model on graduates' propensity for unemployment is estimated. Results suggest that polytechnic graduates face higher unemployment propensity than university graduates, maintaining inequalities present in students' previous trajectories. Policies targeting socioeconomic segregation need to address not only access to higher education but also the transition to the labor market. [ABSTRACT FROM AUTHOR]

Currently, most explored oil fields in Russia are at a late stage of development, and in order to maintain high levels of oil production, it is rational to put into operation fields with hard-to-recover reserves. For complicated oil fields, in particular fields with high-viscosity oil, the known traditional methods of development are ineffective. Therefore, the search for new technologies for the development and operation of such fields to significantly increase oil recovery and intensify production is of fundamental importance. One such method of heat treatment of the bottomhole formation zone is the use of heat and gas generating systems on site. In this work, new results were obtained on physical modeling of thermochemical reaction initiation with delayed-action catalyst (2,2-bis(hydroxymethyl)butanoic acid) filtration tests on composite core models of sandstone and carbonate with foam heat generation and initiating additives of binary type. Using hydrodynamic modelling, the results of laboratory studies were reproduced, and the preliminary efficiency of the developed technology for thermochemical treatment of deposits in the Samara region (Russia) was evaluated. [ABSTRACT FROM AUTHOR]

Spin contributions to the correction of the perihelion precession of binary systems, as a follow up to our previous paper, are obtained for systems such as the OJ287 system, which has a large discrepancy not satisfied by the Schwarzschild metric. In a previous paper, they use the Kerr metric to work out the spin contributions in addition to their previous formulation to make up for this discrepancy. In our method we use the de Sitter and Lense-Thirring precession, along with our alternate correction to the perihelion precession in our previous paper, for the inclusion of spin contributions for binary systems. With the addition of spin contributions, we obtain a theoretical value of 40.3 degrees for the total perihelion precession angle correction of the OJ287 system, very close to the observed value of 39.1 ± 0.1. We also obtain values for two other systems, such as the Sagittarius A*-S2, which also has a slight discrepancy, to test for consistency. We find that our methods are in close agreement with observed value of these binary systems. [ABSTRACT FROM AUTHOR]

It is shown that the introduction of a small orbital eccentricity into the model of a binary system with an exoplanet, which is allowed by errors in determining the radial velocities of the eclipsed star, makes possible to significantly reduce and even eliminate the difference in the wavelength dependences between the observed and theoretical values of the limb darkening coefficients of the star HD 209458. [ABSTRACT FROM AUTHOR]

We present the results of a study of secular resonances in a binary star system and their effects on the formation of terrestrial planets. The systems of our interest are binaries with moderate separations (i.e., smaller than 40 AU) where planets revolve around one of the stars. Using numerical simulations, we demonstrate the appearance and evolution of secular resonances in systems with two giant planets. Results indicate that the perturbation of the binary companion suppresses secular resonances and they do not play a significant role on the formation and orbital architecture of terrestrial planets. Unlike in our solar system where the secular resonance of Saturn confines the formation of terrestrial planets to regions interior to its location, in a binary star, terrestrial planets can form interior and exterior to this resonance. We present details of our simulations and discuss the implications of their results. [ABSTRACT FROM AUTHOR]

We present a progress report of our project aiming to increase the number of known Cepheids in double-lined binary (SB2) systems from six to 100 or more. This will allow us, among other goals, to accurately measure masses for a large sample of Cepheids. Currently, only six accurate Cepheid masses are available, which hinders our understanding of their physical properties and renders the Cepheid mass–luminosity relation poorly constrained. At the same time, Cepheids are widely used for essential measurements (e.g., extragalactic distances, the Hubble constant). To examine Cepheid period–luminosity relations, we selected as binary candidates Cepheids that are too bright for their periods. To date, we have confirmed 56 SB2 systems, including the detection of significant orbital motions of the components for 32. We identified systems with orbital periods up to five times shorter than the shortest reported period to date, as well as systems with mass ratios significantly different from unity (suggesting past merger events). Both features are essential to understand how multiplicity affects the formation and destruction of Cepheid progenitors and what effect this has on global Cepheid properties. We also present eight new systems composed of two Cepheids (only one such system was known before). Among confirmed SB2 Cepheids, there are also several wide-orbit systems. In the future, these may facilitate independent accurate geometric distance measurements to the Large and Small Magellanic Clouds. [ABSTRACT FROM AUTHOR]

We present the results of our study of the X-ray pulsar IGR J21343+4738 based on NuSTAR, Swift, and SRG observations in the wide energy range 0.3–79 keV. The absence of absorption features in the energy spectra of the source, both averaged and phase-resolved ones, has allowed us to estimate the upper and lower limits on the magnetic field of the neutron star in the binary system, and G, respectively. Our spectral and timing analyses have shown that IGR J21343+4738 has all properties of a quasi-persistent X-ray pulsar with a pulsation period of s and a luminosity erg s . Our analysis of the long-term variability of the object in X-rays has confirmed the possible orbital period of the binary system days previously detected in the optical range. [ABSTRACT FROM AUTHOR]

Diffuse scattering is a component of the powder pattern bearing information on the local atomic structure and disorder of crystalline materials. It is visible in the X-ray diffraction patterns of binary structures like Ag 2 O, which has a large mean squared displacement for its constituent elements. Pair distribution function (PDF) analysis is widely employed to extract this local structural information, embedded in the widths of PDF peaks. However, obtaining the PDF from experimental data requires a Fourier transform, which introduces aberrations in the transformed data due to instrument resolution, complicating the distinction between its static and dynamic components. In this work, the analysis of thermal diffuse scattering is performed directly on the X-ray powder pattern, using the traditional Rietveld method integrated with a correlated displacement model for atomic pairs. The Ag 2 O case study data were collected using synchrotron radiation at room temperature, supplemented by laboratory experiments up to 200°C. An Einstein model was used to obtain the harmonic and anharmonic force constants of the system. The force constants were also obtained via density functional theory and ab initio molecular dynamics simulations and showed similar values to the experiments. The analysis reveals the complex dynamic structure of Ag 2 O, characterized by high anisotropy in phonon dispersion relations and the presence of soft phonon modes, which explain the significant displacement parameters observed. The proposed approach can be easily employed for other binary or more complex systems to understand the dynamics of local forces through X-ray diffraction analysis., Competing Interests: The authors declare no conflict of interest., (© Marcelo Augusto Malagutti et al. 2025.)

Classifications are a basic tool for research, which allow summarizing the diversity of objects in a number of categories that fits the cognitive abilities of the human mind. Their relevance for higher education is emphasized by the differentiation of institutional profiles. Yet, unlike in the US, there is currently no classification of European Higher Education Institutions (HEIs). This paper fills this gap by developing a classification of European HEIs, which focuses on differences in activity profiles and subject scope. To this aim, it uses data from an enriched version of the European Tertiary Education Register on a sample of more than 2000 HEIs in a large number of European countries. The classification comprises six classes that occupy distinct positions in a configuration space defined by two dimensions, i.e. research vs. educational orientation and subject specialization. Ex-post analysis shows that classes are identifiable and can be attributed meaningful labels; the class of research universities comprises most European HEIs competing in international rankings, while a class of generalist HEIs with lower research orientation that cuts across the traditional distinction between universities and Universities of Applied Sciences can be distinguished. Furthermore, three classes of specialist HEIs can be identified. The classification provides a meaningful representation of European higher education that is more fine-grained than the distinction between university and non-university sectors while remaining parsimonious. We, finally show how national categories map to the classification, displaying its potential to compare differences in national institutional settings across Europe. [ABSTRACT FROM AUTHOR]

Background. Increased interest in agricultural production is enjoyed by liquid fertilizers, as well as their combined use with physiologically active substances that help accelerate the growth and development of plants and obtain high yields. Purpose is to study the mutual influence of one of the main components of liquid fertilizer, i.e. calcium nitrate and monoethanolammonium acetate in the system: Ca(NO3)2-CH3COOH∙NH2C2H4OH-H2O, Methodology. The calcium content was determined by the volumetric complexometric method, the content of elemental nitrogen, carbon, hydrogen was carried out according to the procedure, and X-ray diffraction analysis was also applied. Originality. It has been established that a new phase substance of calcium nitrate with monoethanolammonium Ca(NO3)2∙NH2C2H4OH is formed in this system whose composition is confirmed by the results of X-ray diffraction and chemical analyses. Findlings.The solubility diagram of the Ca(NO3)2-CH3COOH∙NH2C2H4OH-H2O, system revealed crystallization fields: ice, four-, three-, and two-water calcium nitrate, acetic acid, monoethanolammonium acetate, and Ca(NO3)2∙NH2C2H4OH. The results contribute to the production of a liquid fertilizer based on the complex nitric acid decomposition of dolomite and a physiologically active substance. [ABSTRACT FROM AUTHOR]

A methodology, based on the Gibbs‐Duhem equation, is developed to study the thermodynamic consistency of liquid–liquid equilibrium (LLE) data. The method proposes evaluating the experimental data in two ways: (a) integral‐form, verifying dependences among variables in the same phase, both for temperatures: T̂j=κTεT,j0−Tj,exp−Tj,cal, and compositions: x̂1,jJ=κxεx1J,j0−x1,j,expJ−x1,j,calJ, and (b) differential‐form, which validates relationships between the compositions of each phase by ζ̂j=κζεζ,j0−ζj,exp−ζj,cal. A coverage factor κ is introduced in both approaches to define the degree of confidence of the evaluation using a database (T, x1I,x1II) of 50 binary systems to define the limits of inconsistency. With κ = 3, more than 60% of the set is accepted (κ > 3 falls to 38%) providing a guarantee of quality for LLE data. The results show that the consistency test can detect errors in the set {data + model} under study, although the absence of a reference state for the LLE gives the model a limited sensitivity to systematic errors. [ABSTRACT FROM AUTHOR]

In the present paper, within the framework of stationary axisymmetric spacetimes, binary systems composed of two unequal co- and counter-rotating extreme Kerr-Newman black holes separated by a massless strut are reported. The metric describing both configurations is introduced in a closed analytical form in terms of five arbitrary parameters: the masses Mi, electric charges Qi, and a coordinate distance R. We obtain novel results from these configurations; in particular, those related to the merging process.

The emission line spectra of WR stars are often formed completely in the optically thick stellar wind. Hence, any assumption on the wind velocity law in a spectral analysis has a profound impact on the determination of the stellar parameters. By comparing Potsdam Wolf-Rayet (PoWR) model spectra calculated with different β laws, we show that the velocity field heavily influences the spectra: by using the appropriate β laws, the entire range of late and early types can be covered with the same stellar model. [ABSTRACT FROM AUTHOR]

The properties studying results of ceramics based on strontium, calcium and sodium niobates, which vary from the conditions of synthesis, sintering, and mechanical processing, are presented. The evolution of the grain structure of objects is traced depending on their phase filling during concentration changes in the composition and thermodynamic prehistory (preparation conditions).

The properties studying results of ceramics based on strontium, calcium and sodium niobates, which vary from the conditions of synthesis, sintering, and mechanical processing, are presented. The evolution of the grain structure of objects is traced depending on their phase filling during concentration changes in the composition and thermodynamic prehistory (preparation conditions). [ABSTRACT FROM AUTHOR]

Mutual solubilities of water with n-alkanes, cycloalkanes, iso-alkanes (branched alkanes), alkenes, alkynes, alkadienes, and alkylbenzenes were calculated at 298 K for 153 systems not yet measured. Recommended data for 64 systems reported in the literature were compared with the predicted values. The solubility of the hydrocarbons in water was calculated with a thermodynamically based equation, which depends on specific properties of the hydrocarbon. The concentration in the second coexisting liquid phase (water in hydrocarbon) was calculated using liquid-liquid equilibrium with an equation of state, which takes into account the self-association of water and co-association of water with π-bonds of the hydrocarbons. [ABSTRACT FROM AUTHOR]

The Ag2MoO4–Cs2MoO4 system was studied by powder X-ray diffraction, the formation of a new double molybdate CsAg3(MoO4)2 was established, its single crystals were obtained, and its structure was determined. CsAg3(MoO4)2 (sp. gr. P3¯, Z = 1, a = 5.9718(5), c = 7.6451(3) Å, R = 0.0149) was found to have the structure type of Ag2BaMn(VO4)2. The structure is based on glaserite-like layers of alternating MoO4 tetrahedra and Ag1O6 octahedra linked by oxygen vertices, which are connected into a whole 3D framework by Ag2O4 tetrahedra. An unusual feature of the Ag2 atom environment is its location almost in the centre of an oxygen face of the Ag2O4 tetrahedron. Caesium atoms are in cuboctahedral coordination (CN = 12). We determined the structures of the double molybdate of rubidium and silver obtained by us previously and a crystal from the solid solution based on the hexagonal modification of Tl2MoO4, which both are isostructural to glaserite K3Na(SO4)2 (sp. gr. P3¯m1). According to X-ray structural analysis data, both crystals have nonstoichiometric compositions Rb2.81Ag1.19(MoO4)2 (a = 6.1541(2), c = 7.9267(5) Å, R = 0.0263) and Tl3.14Ag0.86(MoO4)2 (a = 6.0977(3), c = 7.8600(7) Å, R = 0.0174). In the case of the rubidium compound, the splitting of the Rb/Ag position was revealed for the first time am ong molybdates. Both structures are based on layers of alternating MoO4 tetrahedra and AgO6 or (Ag, Tl)O6 octahedra linked by oxygen vertices. The coordination numbers of rubidium and thallium are 12 and 10

Higher order corrections are obtained for the perihelion precession in binary systems like OJ 287, Sagittarius A*-S2 and H1821+643 using both the Schwarzschild metric and the Kerr metric to take into account the spin effect. The corrections are performed considering the third root of the motion equation and developing the expansion in terms of parameters related to each other and depending on orbit variables. The results are compared with those obtained in a previous paper. [ABSTRACT FROM AUTHOR]

Originally introduced in connection with general relativistic Coriolis forces, the term frame- dragging is associated today with a plethora of effects related to the off-diagonal element of the metric tensor. It is also frequently the subject of misconceptions leading to incorrect predictions, even of nonexistent effects. We show that there are three different levels of frame-dragging corresponding to three distinct gravitomagnetic objects: gravitomagnetic potential 1-form, field, and tidal tensor, whose effects are independent, and sometimes opposing. It is seen that, from the two analogies commonly employed, the analogy with magnetism holds strong where it applies, whereas the fluid-dragging analogy (albeit of some use, qualitatively, in the first level) is, in general, misleading. Common misconceptions (such as viscous-type "body-dragging") are debunked. Applications considered include rotating cylinders (Lewis-Weyl metrics), Kerr, Kerr-Newman and Kerr-dS spacetimes, black holes surrounded by disks/rings, and binary systems. [ABSTRACT FROM AUTHOR]

An approach is developed to describe the ordering of components in a regular structure of a binary А0.5В0.5 system within the lattice gas model with the combined application of the fragment method (FM) and the quasi-chemical approximation (QCA). FM enables an accurate calculation of statistical sums of configurational contributions of components on a small fragment, which includes indirect correlations. QCA contributions reflect direct correlations between interacting particles. The effect of components described in QCA on the occupancy states of fragment sites is taken into account through local external fields considered as a calibration function improving the accuracy of calculating thermodynamic functions with taking into account indirect correlations in the entire density and temperature ranges. The effect of indirect correlations on the temperature dependences of ordering and the ordering critical temperature as well as on its size dependence of cubic domains is analyzed. The domain boundary is set by an external field that changes the character of the distribution of system components in the near-surface region in comparison with their distribution in the phase volume, which makes the total system heterogeneous. The dependence of a decrease in the ordering critical temperature as the domain side decreases with taking into account indirect correlations is calculated for the first time. The role of domain sides in related situations, including ferroelectrics, is discussed along with the prospects of utilizing the new method. [ABSTRACT FROM AUTHOR]

Methodological studies of spectral characteristics and statistical analysis of flicker noise are presented on the example of two data samples (2016–2017) on the X-ray nova A0620-00. The results obtained indicate the nature of flicker noise as aperiodic phenomenon in stellar atmospheres and in regions of interaction between stars in binary systems, including phenomena of a flare nature. We showed that flicker noise is described by distributions of non-negative random variables: gamma distribution and Weibull distribution, which makes it related to atmospheric processes in meteorology and geological processes (earthquakes). Modeling of these processes shows structural correspondence to real data (Hurst diagrams), and also indicates the presence of additional unaccounted for noise of a presumably Gaussian nature. The performed studies give recommendations to supplement the models of the light curves of binary astrophysical systems with the gamma distribution and the Weibull distribution. [ABSTRACT FROM AUTHOR]

A model is built of the sensory process in sensors based on CeO2–In2O3 nanocomposites. It is shown there is an increase in the response to hydrogen and a shift in the maximum of the sensory curve to lower temperatures with respect to the single system In2O3. It is established that the obtained results correspond to experimental data in the literature. [ABSTRACT FROM AUTHOR]

A new technique that utilizes surface integrals to find the force, torque and potential energy between two non-spherical, rigid bodies is presented. The method is relatively fast, and allows us to solve the full rigid two-body problem for pairs of spheroids and ellipsoids with 12 degrees of freedom. We demonstrate the method with two dimensionless test scenarios, one where tumbling motion develops, and one where the motion of the bodies resemble spinning tops. We also test the method on the asteroid binary (66391) 1999 KW4, where both components are modelled either as spheroids or ellipsoids. The two different shape models have negligible effects on the eccentricity and semi-major axis, but have a larger impact on the angular velocity along the z-direction. In all cases, energy and total angular momentum is conserved, and the simulation accuracy is kept at the machine accuracy level. [ABSTRACT FROM AUTHOR]

We outline a new method suggested by Conway (CMDA 125:161–194, 2016) for solving the two-body problem for solid bodies of spheroidal or ellipsoidal shape. The method is based on integrating the gravitational potential of one body over the surface of the other body. When the gravitational potential can be analytically expressed (as for spheroids or ellipsoids), the gravitational force and mutual gravitational potential can be formulated as a surface integral instead of a volume integral and solved numerically. If the two bodies are infinitely thin disks, the surface integral has an analytical solution. The method is exact as the force and mutual potential appear in closed-form expressions, and does not involve series expansions with subsequent truncation errors. In order to test the method, we solve the equations of motion in an inertial frame and run simulations with two spheroids and two infinitely thin disks, restricted to torque-free planar motion. The resulting trajectories display precession patterns typical for non-Keplerian potentials. We follow the conservation of energy and orbital angular momentum and also investigate how the spheroid model approaches the two cases where the surface integral can be solved analytically, i.e., for point masses and infinitely thin disks. [ABSTRACT FROM AUTHOR]

Unit operations and processes abound with gas diffusion in liquids, which is a sophisticated phenomenon in which mass transfer is characterized by diffusion coefficient or diffusivity. Compared to diffusion in gas phase, the closely packed liquid molecules strongly influence diffusive mass transfer to the extent that it is impossible to have a general theory for a reasonably accurate estimation of diffusivity in liquids. This situation is further compounded by the fact that diffusivity cannot be measured directly but can only be estimated indirectly with the help of a number of observable properties (eg, mass, volume, pressure, etc). This fact gives rise to a myriad of experimental methods for the determination of gas diffusivity in liquids. These methods report gas diffusivities over widely varying ranges of temperature, pressure, and liquid composition. To provide a state‐of‐the‐art knowledge base for such methods is the objective of this work. The focus is on gas diffusion in binary gas‐liquid systems. Starting with necessary theoretical foundations, we provide a systematic categorization of these methods based on the property change utilized for diffusivity determination. The methods are then concisely described, and the diffusivity data are summarized for over 160 gas‐liquid systems at different temperature and pressure conditions. Empirical correlations are provided for different gas‐liquid systems, which could be used for interpolating gas diffusivity as a function of temperature, pressure, and composition. [ABSTRACT FROM AUTHOR]