bluuebunny/crossref_metadata_2025 huggingface dataset:
Distinctive features of the skin effect in a rough tungsten plate in a strong magnetic field
Authors: Zherebchevskiĭ D. É. , Naberezhnykh V. P. , Chabanenko V. V.
Published: January 2025

The effect that a defect layer on the surface of a thin single-crystal tungsten plate has on the skin effect in a magnetic field perpendicular to the surface of the sample has been studied experimentally for symmetrical and antisymmetrical modes of wave excitation. The behavior of the surface impedance is different for a rough surface than for an electropolished surface. In the case of the symmetric excitation mode, the impedance losses are observed to have maximum value for unknown reasons. An unusual (linear) frequency dependence of the position of the loss maxima on the axis of the magnetic field has been found for both excitation modes. The observed behavior of the smooth dependence of the impedance is attributed to the change in the conditions of electron scattering on the destructured surface.
The de Haas–van Alphen effect for a specific section of the Fermi surface
Authors: Venttsel’ V. A. , Kochkin A. P. , Rudnev A. V.
Published: January 2025

The magnetic field dependence of the amplitude of oscillations has been measured for a specific section of the monster σ in zinc. A calculation has been carried out of the oscillatory part of the moment, due to the section that has an area close to the specific point of the form Sε,pz=Sε,pz0+S′pz−pz0+13!S‴pz−pz03+… Modulation of the amplitude of the oscillations by the Airy function enables the value of (S′/S)(S‴/S)−1/3near the specific point, to be established.
Scattering of electrons by quantum defects
Authors: Morozov A. I. , Sigov A. S.
Published: January 2025

The infrared divergences arising from the scattering of electrons by quantum impurities (impuritons) in normal and superconducting metals are studied. The temperature dependence of the resistance, owing to this mechanism, as well as estimates for the critical densities of the quantum and frozen impurities, leading to localization of impuritons, are derived.
Self-consistent approach to quantum diffusion with strong localization
Authors: Antsygina T. N. , Slyusarev V. A.
Published: January 2025

A generalization of the so-called locator expansion is proposed for the calculation of many-particle Green’s functions which determine the kinetic properties of disordered systems. The localization criterion obtained in the Anderson model on the basis of this approach is in good agreement with the results of computer simulation. The proposed method has been used to describe quantum diffusion in helium solid solutions. The behavior of the diffusion coefficient for 3He impuritons in 4He is in qualitative agreement with that observed experimentally.
Modulated magnetic structures in some monoclinic systems (MnOOH and compounds isomorphic to it)
Authors: Stefanovskiĭ E. P.
Published: January 2025

Possible mechanisms for the formation of modulated magnetic structures in monoclinic antiferromagnets (space group C2h−P21/m) are examined. The corresponding points of the phase transitions from the paramagnetic state into the superstructure are found, and the range of values of the phenomenological parameters of the thermodynamic potential for which the phase transition occurs in the required channel, and the parameters of the superstructures at low temperatures, i.e., far from a phase transition, are determined. Possible experiments on identification of the mechanism for the formation of the incommensurate magnetic phase are discussed.
Effect of an external electromagnetic field on electron drag of dislocations
Authors: Seminozhenko V. P. , Shafranyuk S. E.
Published: January 2025

The effect of an external electromagnetic field on the electron drag of dislocations under conditions of multiphoton absorption at low temperatures is studied. It is shown that a randomly polarized field with frequency Ω ≫ ωq (ωq is the frequency of the dislocation phonon), changing the character of the interaction of the dislocation phonons with current carriers, also changes the friction between the dislocations and the electron gas.
Effect of dimensions of Josephson junctions on their macroscopic quantum properties
Authors: Vasenko S. A. , Likharev K. K.
Published: January 2025

The effect of the finite dimensions of a Josephson junction on the width of the lower band of its energy spectrum is analyzed. It is shown that for those relatively small junctions (dimensions a,b ≲. 10−3 cm) in which the “secondary” macroscopic quantum effects are now under study experimentally, the previously employed “lumped” (zero-dimensional) model is fully adequate. If, however, at least one of the dimensions of the junction is so large that the frequencies of the lower resonance Fiske modes lie below the “gap” frequency, the zeroth oscillations of such modes can appreciably broaden the lower band.
Pressure-induced superconductivity in amorphous GeTe
Authors: Berman I. V. , Brandt N. B. , Kystaubaev T. Z. , Sidorov V. I. , Fisheleva S. B.
Published: January 2025

An insulator–metal transition was observed in amorphous GeTe at a pressure Pc≈ 90 kbar. At pressures P≳ Pc superconductivity appears with the critical temperature Tc, which increases at pressures Pc up to 170 kbar. At higher pressures the curve Tc (P) saturates. The increase in Tc on compression near Pc is attributable to the weakening of localization effects as the pressure from Pc into the metallic region.
Kinetic properties of high-temperature superconductors
Authors: Bezuglyĭ E. V. , Dmitriev V. M. , Dikin D. A. , Kotok L. A. , Svetlov V. N. , Seminozhenko V. P. , Churilov G. E.
Published: January 2025

An anomalous inductive response has been found experimentally in polycrystalline superconducting specimens of Y(La)–Ba(Sr)–Cu–O to a low-frequency (f= 0.1–10 kHz) alternating current. A relation between the observed magnitude of the inductance, L∼1 μH, and the critical current density of the specimen was established, which is explained by the formation in the specimen of a system of superconducting channels with current carrying capacity ≳108 A · cm−2 at T = 4.2 °K.
Features of the resistive state of the superconducting system Y–Ba–Cu–0
Authors: Pan V. M. , Prokhorov V. G. , Kaminskiĭ G. G. , Flis V. S. , Popov A. G. , Vasilenko-Sheremet’ev M. G. , Kuznetsov M. A. , Tret’yachenko K. G. , Valentinov V. D. , Flis A. A.
Published: January 2025

Current-voltage characteristics and their first derivatives have been measured on specimens of the high-temperature superconducting metal oxides Y–Ba–Cu–O. It was shown that the nonlinear behavior of the current-voltage characteristics is due to the existence of weak links in a system of current channels.
Investigation of the temperature dependence of the electrical resistance, Hall effect, and magnetic susceptibility in the system Y–Ba–Cu–O
Authors: Trefilov V. I. , Shulishova O. I. , Brodovoĭ A. V. , Lazorenko V. I. , Lashkarev G. V. , Shevchuk N. V. , Shcherbak I. A.
Published: January 2025

Material with the calculated composition Y1.2Ba0.8CuO4 was obtained in the Y–Ba–Cu–O system by solid-phase synthesis. An attempt was made to separate the “black” and “green” phases arising on synthesis of a ceramic of the calculated composition indicated. The temperature dependences of the electrical resistance, Hall effect and magnetic susceptibility have been measured. The phase responsible for the superconducting state consists of the “black” fraction of the material.
Tunneling in junctions based on metal-oxide superconductors
Authors: Bar’yakhtar V. G. , Boguslavskiĭ Yu. M. , Nevirkovets I. P. , Rudenko É. M. , Shevchuk N. V. , Shulishova O. N. , Shcherbak I. A.
Published: January 2025

The current–voltage characteristics and their derivatives have been studied for tunnel junctions based on metal-oxide superconductors. On the basis of the minimum differential resistance Rd = dV/dI, which is usually associated with the existence of an energy gap in the excitation spectrum of a superconductor, we obtained the following values for Δ at T = 2 °K: Δ = 4.45 meV (2Δ /kTc = 2.75) for La1.8Sr0.2CuO4, Δ = 6.45 meV (2Δ /kTc = 5) for La1.8Ba0.2CuO4, and Δ = 17 meV (2Δ /kTc = 4.4) for Y1.8Ba0.2CuO4.
Tunneling in high-temperature superconductors
Authors: Svistunov V. M. , Revenko Yu. F. , Tarenkov V. Yu.
Published: January 2025

Tunnel junctions were formed on the surface of La–Sr–Cu–O and Y–Ba–Cu–O bulk samples. Their dynamic conductivity is shown to be similar to tunneling in inhomogeneous superconducting systems and to display anomalies due to the energy gap and the phonon spectrum of the oxides.
Theory of two-dimensional topological solitons in antiferromagnets
Authors: Ivanov B. A. , Stefanovich V. A.
Published: January 2025

Two-dimensional topological solitons in a uniaxial antiferromagnet are studied. Two-parameter solitons, whose parameters are the frequency ω of precession of the magnetization around the z axis (z is the distinguished axis of the antiferromagnet) and the velocity of the soliton v are studied. Relations relating the parameters v and ω with the integrals of motion of the equations for the magnetization field of the antiferromagnet—the energy E, the momentum P, and the z projection of the magnetization of the antiferromagnet N—are derived. It is shown that the existence of topological charge in the system does not lead to the appearance of gyrotropic effects. The properties of solitons with large and small radii of localization (large and small values of N, respectively) are studied analytically.
Effect of the electron–phonon interaction on the properties of strong paramagnets
Authors: Povzner A. A. , Timofeev A. A.
Published: January 2025

A theory describing the effect of spin fluctuations on the system of electrons and phonons in strong paramagnets is developed. The renormalization due to spin fluctuations, of the electron–phonon corrections to the electronic and phonon spectra of the materials studied is analyzed with the help of an expression derived for the free-energy functional. The possible mechanisms for singularities in the effect of the electron–phonon interaction on the magnetic susceptibility, heat capacity, and modulus of elasticity of strong paramagnets (for the example of Pd and Nb3Sn) are discussed on the basis of the approach developed.
Low-temperature anomaly of the heat capacity of metallic glasses
Authors: Kovalenko N. P. , Krasnyi Yu. P. , Makhlaĭchuk V. N. , Tsarev V. F.
Published: January 2025

The anomaly in the temperature dependence of the heat capacity of metallic glasses is attributed to two characteristic regions in the dispersion relation of collective excitations. The results of calculations for amorphous Mg and Zn are presented.
Thermal expansion coefficient of crystal with Jahn–Teller centers
Authors: Ivanov M. A. , Fishman A. Ya.
Published: January 2025

We investigated how the nature of the thermal expansion coefficient is changed by Jahn–Teller impurity centers. It is shown that these centers can make a considerable contribution to the thermal expansion coefficient of the system at low temperatures.
Effect of a quantizing magnetic field on the parameters of electrons in Bi1−xSbx alloys
Authors: Arutyunov K. Yu. , Mironova G. A. , Ponomarev Ya. G.
Published: January 2025

A quantizing magnetic field H in the ultraquantum region has been observed to have a strong effect on the spin splitting factor γ = Δspin/Δorb and the cyclotron mass mc of electrons at the point L of the Brillouin zone in the n-type semiconducting layer Bi0.91Sb0.09. The fact that the cyclotron mass mc decreases and the γ-factor tends to unity as H increases is attributed to a pronounced lowering of the Fermi energy in the ultraquantum region. The experimental results are in qualitative and quantitative agreement with the results of the McClure and Choi theory.
Quantum oscillations of the ellipticity and rotation of the polarization plane of ultrasound in a strong magnetic field
Authors: Gudkov V. V. , Zhevstovskikh I. V.
Published: January 2025

Quantum oscillations of the polarization ellipticity and rotation of the polarization plane of ultrasound are observed in a high-purity tungsten sample when ultrasound propagates in the direction of a magnetic field H and the crystallographic [001] axis in the range of magnetic fields above the cyclotron absorption edge.
Relaxation of kink-type solitons in a quasi-one-dimensional antiferromagnet
Authors: Ivanov B. A. , Sukstanskii A. L. , Tartakovskaya E. V.
Published: January 2025

The nonequilibrium thermodynamics of a gas of kink-type solitons is investigated in a one-dimensional antiferromagnet with rhombic anisotropy. The temperature dependence of the kinetic coefficients is determined, and the nature of the low-temperature divergence of the diffusion coefficient is analyzed.
Quantum effects in the superconducting ceramic Y1Ba2Cu3O7−x
Authors: Verkin B. I. , Bondarenko S. I. , Lukashenko A. V. , Shablo A. A. , Svechkarev I. V. , Seminozhenko V. P. , Churilov G. E. , Komashko V. A.
Published: January 2025

Experimental results on quantum interference in a superconducting circuit with two tunnel contacts containing an insert of high-temperature Y1Ba2Cu3O7−x ceramic are reported. It is shown that a pressure point contact made from a point of Y–Ba–Cu–O ceramic and a planar surface of POS-61 solder possesses characteristics of a Josephson junction at 4.2 K. The conclusion is drawn that long-range order and pair correlations of charge carriers exist in these ceramics.
Quantum diffusion in solid deuterium
Authors: Bagatskii M. I. , Krivchikov A. I. , Manzhelii V. G. , Minchina I. Ya. , Muromtsev P. I.
Published: January 2025

Quantum diffusion (configurational relaxation) has been detected in solid deuterium. Evidence of its existence has been obtained in calorimetric studies of deuterium containing 2.8% paradeuterium. The characteristic configurational relaxation time τ = 630±50 h (T = 1.65 °K) is in good agreement with the predictions of the resonance-conversion model of Oyarzun and Van Kranendonk. The conversion rate constant in deuterium is determined to be k = 4.8⋅10−4 h−1.
Effect of dislocations and twin boundaries on critical fields in superconducting niobium
Authors: Dolgin A. M.
Published: January 2025

The behavior of niobium single crystals containing dislocations or twin boundaries created by plastic deformation at 4.2 K is studied in a magnetic field. An increase is observed in the upper critical field of superconductivity due to an increase in the Ginzburg–Landau parameter for a crystal with dislocations and to the emergence of localized twinning plane superconductivity (TPS) for a crystal with twin boundaries. Considerably higher values of the critical TPS fields in deformation twins in comparison with the twin boundaries in bicrystals {I. N. Khlyustikov and M. S. Khaikin, Zh. Eksp. Teor. Fiz. 89, 1846 (1985) [Sov. Phys. JETP 62, 1065 (1985)]}, as well as a profound effect of heating of strained samples on the TPS critical parameters, can be attributed to the high internal stresses induced in the vicinity of twin boundaries by plastic deformation.
Thermoelectric effects in point-contact junctions in the thermal limit
Authors: Itskovich I. F. , Moskalets M. V. , Shekhter R. I. , Kulik I. O.
Published: January 2025

The theory of nonlinear electric conductivity of small point contacts between different metallic electrodes (heterojunctions) is constructed. The maximum of the temperature distribution obtained for short mean free paths of electrons and phonons lies in the material with lower electric conductivity. Nonlinear corrections to the current-voltage characteristics (IVC) due to the electron-phonon interaction (symmetric part) and thermoelectric (Seebeck) effect (asymmetric part) are calculated. Nonlinearity of IVC caused by structural transformations and resulting in the heating of the contact region is also analyzed.
Magnetic response of spin-density waves in a quasi-one-dimensional system with a small deviation from the half-filling of the energy band
Authors: Palistrant M. E. , Chernei M. D.
Published: January 2025

Magnetic response of spin density waves is studied in a quasi-one-dimensional Hubbard model with a small deviation from the half-filling level of the energy band (μ≠0). Umklapp processes are taken into consideration. The angular anisotropy of the magnetic susceptibility and its temperature dependence are studied under the assumption of an arbitrary direction of the magnetic field.
Band relaxation time of excitons in interaction with acoustic phonons
Authors: Fugol’ I. Ya. , Tarasova E. I.
Published: January 2025

The energy relaxation time of excitons along the dispersion curve is investigated theoretically under the condition of single-phonon scattering by acoustic lattice oscillations. The relaxation rate and time of the excitation to an arbitrary (lower) value of the wave number k are analyzed for excitons of the lowest bands in Ne, Ar, Kr, and Xe cryocrystals as a function of the exciton-phonon interaction force. The quasiparticle relaxation pattern at T = 0 is investigated with allowance for thermally stimulated scattering by phonons. It is shown that a critical temerpature Tc exists in each crystal, separating the intervals in which the diffusion of free excitons is influenced predominantly by band relaxation and by self-trapping; the value of the critical temperature depends on the height of the exciton self-trapping barrier.
Low-temperature heat capacity of disordered solids
Authors: Akhiezer I. A. , Druinskiĭ E. I.
Published: January 2025

The low-temperature heat capacity of disordered solids, consisting of separate atoms (metallic glasses, highly dispersed polycrystals with a simple lattice, and crystals with a high density of dislocations) is studied in the simplest microscopic model. The conditions under which a term linear in the temperature (or in the more general case, a non-Debye power-law term) appears in the expression for the heat capacity are determined.
Generalization of the local pair model
Authors: Pastur L. A. , Slyusarev V. A.
Published: January 2025

A model of the superconducting transition in a system of interacting narrow- and wide-band carriers is proposed. It is shown in the self-consistent field approximation that the transition occurs for repulsion between the narrow-band carriers at one site as well as for attraction if it does not exceed a certain critical value.
Anomalies in the thermal expansion of the ceramic YBa2Cu3O7
Authors: Prokhvatilov A. I. , Strzhemechnyĩ M. A. , Isakina A. P. , Baryl’nik A. S. , Demirskiĩ V. V.
Published: January 2025

X-ray studies have been carried out of the lattice parameters of the ceramic YBa2Cu3O7 in the temperature range from 4.5 to 293 °K. A sharp anomaly was found in the temperature dependence of the coefficients of linear thermal expansion in the region of the superconducting transition, which is of a noticeably anisotropic character. The effective increase in volume of the rhombohedral cell over the anomaly amounts to about 0.4%. An unusual form for the change in the width of the diffraction lines which were determined was also noted near Tc, which might be due to the appearance of modulated positions of the oxygen atoms in the interbarium planes.
Macroscopic character of orientational domain walls in antiferromagnets of the UO2 type
Authors: Bar’yakhtar V. G. , Leonov I. A. , Sobolev V. L.
Published: January 2025

It is shown that a domain wall in an antiferromagnet of the UO2 type, separating domains with different orientation of the unit antiferromagnetism vectors, can have a macroscopic thickness. This character of the domain wall is a result of the competition between the quadratic and biquadratic terms in the exchange Hamiltonian. A topological justification is given for the possibility of the appearance of a macroscopic domain wall.
Quantum interference effects in concentrated Ni–Fe–Cr alloys
Authors: Pecherskaya V. I. , Butenko A. V. , Bol’shutin D. N.
Published: January 2025

The temperature dependences of the electric resistance, magnetoresistance, and magnetic susceptibility of concentrated nickel-based alloys were studied. Electric resistance minima, which are virtually unaffected by the applied magnetic field, were observed at low temperatures. Changes in the magnetoresistance in alloys with different compositions were studied. Careful analysis of the observed effects made it possible to describe them on the basis of the quantum theory of weak localization and interaction of electrons in disordered systems.
Influence of the nature of surface scattering of electrons on the reflection of ultrasound from a metal
Authors: Bebenin N. G. , Yartseva N. S.
Published: January 2025

The influence of the nature of surface scattering of electrons on the reflection of transverse ultrasonic waves from a metal is investigated at low temperatures in the presence of doppleron–phonon scattering. It is shown that the ultrasound reflection coefficient depends only slightly on whether the electron scattering is specular or diffuse, whereas the surface impedance and quantities characterizing the reciprocal conversion of electromagnetic and acoustic waves are highly sensitive to this distinction.
Effect of surface scattering of electrons on the current states in tungsten
Authors: Boiko V. V. , Landysheva G. N. , Ovchinnikova L. V.
Published: January 2025

The peculiarities of the current states in tungsten arising due to irradiation of samples with high-amplitude (up to 150 Oe) rf waves are described. The frequency dependence of the moment (Hc∼) of the emergence of these states is determined. It is shown that Hc∼ is an exponential function of frequency, the exponent depending on the nature of electron scattering at the sample surface. The contribution of electrons multiply reflected by the sample surface to the rectified high-frequency current and the hysteresis of current states is determined.
Fluctuation effects in ultralow temperature easy-plane magnets with dipole interaction
Authors: Zubov É. E. , Krivoruchko V. N.
Published: January 2025

High-temperature expansion of free energy is obtained by taking into account the spin fluctuations for an ultralow temperature easy-plane magnet with comparable values of exchange, dipole and one-ion interactions. The dependence of the thermodynamic properties, including Curie temperature, on system parameters is analyzed. It is shown that spin fluctuations may inhibit or even completely prevent the long-range magnetic ordering predicted by the molecular field theory.
Magnon spectrum and phase transitions in easy-plane magnets
Authors: Pereverzev Yu. V. , Borisenko V. G.
Published: January 2025

The method of two-time delaying Green’s functions is used to study the magnon spectrum and stability boundary (from the divergence of the transverse magnetic susceptibility) of the paramagnetic phase of easy-plane magnets with one-ion anisotropy in a magnetic field perpendicular to the easy plane. The behavior of the phase boundary in the low-frequency region is studied. An equation is derived for the line along which the energy of low-frequency magnons vanishes for arbitrary quasi-momenta. The coordinates of the line terminal on the phase curve are obtained. The change in the shape of the phase boundary with a decrease in the spatial dimension is considered.
Temperature dependence of parameters of quantum ferroelectrics
Authors: Konsin P. I. , Kristoffel N. N. , Örd T. A.
Published: January 2025

Temperatures dependences of dielectric susceptibility (χ) and soft-mode frequency of a quantum ferroelectric are obtained in the framework of the vibronic theory of structural phase transitions. It is shown that at low temperatures χ∼T2−Tc2−1 in reasonable approximations for the paraelectric phase (Tc is the temperature at which the soft-mode frequency vanishes).
On the possibility of coherent phonon gain in a system of nonuniformly broadened local electron centers
Authors: Vinetskii V. L. , Godenko L. P.
Published: January 2025

A model of electron transitions involving two phonons is proposed, in which a gain of phonons of a given mode is possible. The probability of electron transitions is calculated. The kinetic equation for phonon density is solved, and the value of the linear gain factor is calculated.
Anisotropy of the quantum correction to the magnetic conductivity of disordered beryllium films
Authors: Butenko A. V. , Bukhshtab E. I. , Kashirin V. Yu.
Published: January 2025

The angular dependences of the quantum correction to the magnetic conductivity of beryllium films with a thickness of ∼10−6 cm. The phase shift length of the electron wave function decreases with increasing temperature and the magnetic-conductivity anisotropy, which characterizes the “two-dimensionality” of the localization effect, vanishes. The anisotropy is observed to undergo a reduction, corresponding to the “three-dimensionalization” effect, when the film thickness increases as well as when the film thickness decreases in the case of the thinnest films. This is attributed to the influence that structural inhomogeneities in very thin films have on the phase shift length.
The passive core snubber based on Fe-based amorphous alloy for −400 kV negative ion based neutral beam injector of comprehensive research facility for fusion technology
Authors: Liu Bo , Liu Zhimin , Jiang Caichao , Liu Sheng , Pan Junjun , Chen Shiyong , Wei Wei , Liu Wei , Xie Yuanlai
Published: January 2025

Comprehensive Research Facility for Fusion Technology (CRAFT) is a technology development and validation platform for fusion technology in China. Neutral beam injection is one of the most important auxiliary heating and current drive methods in magnetically confined controlled fusion. Consequently, a negative ion based neutral beam injector (NNBI) testing facility with a beam energy of 400 keV is being developed in CRAFT. The core snubber, which provides an equivalent parallel resistance and inductance, will be used as the main surge suppression method for the CRAFT NNBI power supply system. In this paper, a core snubber for CRAFT NNBI based on Fe-based amorphous alloy is designed. The transmission line resistance, inductance, and capacitance of the high-voltage circuit have been considered during the design process. The snubber is made thin and long for even weight distribution while ensuring choke capacity. One of the snubber units was tested on the test bench. The test results indicate that the choke capacity of the snubber meets the requirement and can achieve significant suppression of peak ignition current and oscillation.
Influence of nonequilibrium vibrational dynamics on spin selectivity in chiral molecular junctions
Authors: Smorka R. , Rudge S. L. , Thoss M.
Published: January 2025

We explore the role of molecular vibrations in the chirality-induced spin selectivity (CISS) effect in the context of charge transport through a molecular nanojunction. We employ a mixed quantum–classical approach that combines Ehrenfest dynamics for molecular vibrations with the hierarchical equations of motion method for the electronic degrees of freedom. This approach treats the molecular vibrations in a nonequilibrium manner, which is crucial for the dynamics of molecular nanojunctions. To explore the effect of vibrational dynamics on spin selectivity, we also introduce a new figure of merit, the displacement polarization, which quantifies the difference in vibrational displacements for opposing lead magnetizations. We analyze the dynamics of single trajectories, investigating how the spin selectivity depends on voltage and electronic–vibrational coupling. Furthermore, we investigate the dynamics and temperature dependence of ensemble-averaged observables. We demonstrate that spin selectivity is correlated in time with the vibrational polarization, indicating that the dynamics of molecular vibrations is the driving force of CISS in this model within the Ehrenfest approach.
Interaction between arc root stagnation-transition and contact erosion during direct current air circuit breaker interruption
Authors: Duan Wei , Li Jing , Bao Yuliang , Huang Hao , Yang Juncheng , Liu Shuxin , Cao Yundong
Published: January 2025

The contact erosion during the arc duration affects the attachment position of arc roots, directly determining the arc motion speed. In this paper, a two-way coupling model is proposed to study the interaction between contact edge erosion and arc root stagnation-transition during direct current air arc interruption. A two-dimensional transient model for contact erosion and droplet splashing is established using an improved level-set method, combined with the magnetohydrodynamic model of arc plasma and contact energy transfer, considering the mass transfer, heat transfer, and fluid flow during the arc root stagnation-transition comprehensively. The model's accuracy is verified through experiments. The results show that the arc root stagnation forms molten pool or even droplet splashing. Vortices below the moving contact interfere favorably with arc root transition. However, contact deformation induced by erosion affects heat dissipation at the arc root, weakens the vortices' aerodynamic performance, hastens vortex bubble rupture, and delays arc root transition. Increasing breaking speed and arc-blowing magnetic induction intensity shortens stagnation time and reduces edge erosion. However, the breaking speed more than 5 m/s or the magnetic induction intensity more than 50 mT shows no significant improvement on the arc root transition speed, while erosion intensifies when magnetic induction intensity exceeds 50 mT.
Magnetocaloric effects in the prototype spin crossover complex [Fe(L)2](BF4)2 in pulsed magnetic fields
Authors: Lünser Klara , Salazar Mejía Catalina , Gottschall Tino , Gürpinar Kübra , Atakol Orhan , Kavak Eyüp , Emre Baris , Stern-Taulats Enric , Mañosa Lluís
Published: January 2025

Spin crossover (SCO) complexes have been shown to exhibit giant mechanocaloric effects. Due to the change of magnetization at the spin crossover transition, they are also expected to show magnetocaloric effects. However, experimental studies on the magnetocaloric properties in SCOs are scarce. Here, we have studied the magnetocaloric response in the SCO complex [Fe(L)2](BF4)2, [L = 2,6-di(pyrazol-1-yl)pyridine] using pulsed magnetic fields. We show that applying a magnetic field can induce a partial transformation from the low spin to the high spin state. We directly measure the adiabatic temperature change of the transformation for different initial sample temperatures and magnetic fields and compare them with calculations using the Clausius–Clapeyron equation. While we found a large change in entropy of 70 J kg−1 K−1 at 50 T, the corresponding temperature change of 1.5 K is small due to the weak dependence of the transformation temperature on the magnetic field. Our study enhances the knowledge of caloric effects in SCO complexes, which so far have mainly focused on mechanocaloric studies.
A real-time multi-objective HVAC load optimization integrated with home microgrid scheduling
Authors: Aliç Oğuzkağan , Başaran Filik Ümmühan
Published: January 2025

Ensuring cost-effective and comfortable operation of residential heating, ventilation, and air conditioning (HVAC) systems is crucial for both end-users' financial well-being and thermal comfort. Furthermore, the growing popularity and affordability of on-site energy generation and storage facilities in residential premises offer a potential solution to alleviate the demand for electricity from the grid. Hence, this study is established upon two primary objectives: (i) to establish a desirable equilibrium between the cost of HVAC usage and the avoidance of thermal discomfort among end-users within a multi-objective optimization framework, incorporating a constraint decoupling strategy enabling the real-time HVAC load scheduling, and (ii) to efficiently allocate power generated by on-site sources and stored energy in a home microgrid, utilizing a real-time bi-directional demand response scheme that minimizes costs without compromising the thermal comfort of end-users. This study's validation encompasses various end-user profiles and scenarios, with the results demonstrating the model's capacity to accomplish a favorable balance between cost and comfort for end-users. Furthermore, the implementation of a home microgrid leads to a substantial reduction in daily electricity expenses for end-users from consumer perspective, while it also contributes to a notable decrease in the grid's peak-to-average electricity demand ratio from the utility perspective.
Study on the propeller wake dynamics using multiscale proper orthogonal decomposition
Authors: Huang Hao , Li Mijian , Wang Lianzhou
Published: January 2025

Reduced-order analysis is employed to comprehend and elucidate the dominant spatiotemporal turbulent structures that play a pivotal role in the evolution of propeller wake dynamics. The evolution of propeller wake vortices encompasses a cyclical process from stability to instability as well as a multiscale progression from coherence to disintegration. Consequently, this paper utilizes a multiscale proper orthogonal decomposition (mPOD) model to investigate the dynamic characteristics of propeller wake under various conditions simulated via the delayed detached-eddy simulation method. The findings are then compared with data obtained through proper orthogonal decomposition (POD). The comparison of simulation results with experimental data, along with a grid convergence study, confirms the reliability of the numerical simulation outputs used as inputs for modal analysis. The results indicate that the dominant frequency components associated with the flow modes obtained from mPOD decomposition are relatively singular, which facilitates a better explanation of the propeller wake flow phenomena and elucidates the underlying flow mechanisms. The mPOD modes encompass the dominant flow modes contributing at different scales during the evolution of the propeller wake. In addition, the destabilization mechanisms of propeller wakes under different loading conditions are also elaborated based on the reduced-order analysis.
Influence of vibrational and chemical non-equilibrium on the velocity-gradient and the pressure-Hessian fields in compressible turbulence
Authors: Srivastava Shishir , Sinha Sawan S.
Published: January 2025

The influence of vibrational and chemical non-equilibrium on the dynamics of velocity gradients and pressure-Hessian tensors is investigated in this study. Such non-equilibrium flows typically occur in high-speed compressible turbulence at elevated temperatures, as observed in reentry vehicles or hypersonic flights. In the first part of the study, we derive the exact evolution equations for the velocity gradients and pressure-Hessian tensors under vibrational and chemical non-equilibrium conditions. We identify the inertial, vibrational, and chemical mechanisms in this evolution equation. In the second part of this study, we focus on assessing the relative importance of these mechanisms across different simulation cases. In this work, we present direct numerical simulations of isotropic decaying turbulence, which consider both vibrational and chemical non-equilibrium effects. It is found that in the presence of chemical and vibrational non-equilibrium, (i) vibrational relaxation processes are expedited in terms of mean and fluctuating flow fields. (ii) Vortical fluctuations increase while dilatational fluctuations are suppressed. (iii) The relative strength of the pressure-Hessian tensor compared to the velocity gradient tensor is reduced. (iv) The explicit effects of vibrational mechanisms on the pressure-Hessian evolution equation are diminished, whereas chemical mechanisms substantially influence the dynamics compared to inertial mechanisms throughout the turbulence decay process. This study highlights the need for robust turbulence closure models for chemical mechanisms to accurately capture the effects of thermal non-equilibrium on the dynamics of velocity gradients in compressible flows.
Unveiling heat transfer mechanisms in rotational fluid systems: A teacup perspective
Authors: Verma Gopal , Saraj Chaudry S. , Mehlawat Kavita , Li Longnan , Li Wei
Published: January 2025

The allure of rotating systems and their heat transfer behaviors captivates both researchers and practitioners due to their theoretical significance and practical utility. This research delves into the cooling phenomenon on the outer surface during periodic stirring of hot or cold water/tea, serving as a key to unraveling the underlying mechanisms. Utilizing a combination of experimental measurements and numerical simulations, we clarify the dynamics of water and complex fluids. This study offers a straightforward tool for swift heat transfer rate measurements, providing valuable insights into optimizing heat transfer processes across scientific and industrial domains.
The value of returning a sample of the Martian atmosphere
Authors: Swindle Timothy D. , Pack Andreas , Schwenzer Susanne P. , Young Edward D.
Published: January 2025

The elemental and isotopic abundances of major species in the Martian atmosphere have been determined, but analyses often lack sufficient precision, and those of minor and trace species are frequently not well known. Many important questions about the evolution and current state of Mars require the kind of knowledge that can be gained from analysis of a returned sample of the Martian atmosphere. Key target species include the noble gases, nitrogen, and various species containing carbon, hydrogen, and oxygen, such as methane. More detailed analyses will no doubt provide measurements of other species that will allow insights of their own. These volatiles can constrain the origin of the Martian atmosphere, exchange of volatiles between the surface and interior, polar processes, and (in the case of methane) the possibility of extant biology on Mars.
Distinct and interdependent functions of three RING proteins regulate recombination during mammalian meiosis
Authors: Ito Masaru , Yun Yan , Kulkarni Dhananjaya S. , Lee Sunkyung , Sandhu Sumit , Nuñez Briana , Hu Linya , Lee Kevin , Lim Nelly , Hirota Rachel M. , Prendergast Rowan , Huang Cynthia , Huang Ivy , Hunter Neil
Published: January 2025

During meiosis, each pair of homologous chromosomes becomes connected by at least one crossover, as required for accurate segregation, and adjacent crossovers are widely separated thereby limiting total numbers. In coarsening models, this crossover patterning results from nascent recombination sites competing to accrue a limiting pro-crossover RING-domain protein (COR) that diffuses between synapsed chromosomes. Here, we delineate the localization dynamics of three mammalian CORs in the mouse and determine their interdependencies. RNF212, HEI10, and the newest member RNF212B show divergent spatiotemporal dynamics along synapsed chromosomes, including profound differences in spermatocytes and oocytes, that are not easily reconciled by elementary coarsening models. Contrasting mutant phenotypes and genetic requirements indicate that RNF212B, RNF212, and HEI10 play distinct but interdependent functions in regulating meiotic recombination and coordinating the events of meiotic prophase-I by integrating signals from DNA breaks, homolog synapsis, the cell-cycle, and incipient crossover sites.
Completion of lunar magma ocean solidification at 4.43 Ga
Authors: Dauphas Nicolas , Zhang Zhe J. , Chen Xi , Barboni Mélanie , Szymanowski Dawid , Schoene Blair , Leya Ingo , McKeegan Kevin D.
Published: January 2025

Crystallization of the lunar magma ocean yielded a chemically unique liquid residuum named KREEP. This component is expressed as a large patch on the near side of the Moon and a possible smaller patch in the northwest portion of the Moon’s South Pole-Aitken basin on the far side. Thermal models estimate that the crystallization of the lunar magma ocean (LMO) could have spanned from 10 and 200 My, while studies of radioactive decay systems have yielded inconsistent ages for the completion of LMO crystallization covering over 160 My. Here, we show that the Moon achieved >99% crystallization at 4,429 ± 76 Ma, indicating a lunar formation age of ~4,450 Ma or possibly older. Using the
176
Lu–
176
Hf decay system (
t
1/2
= 37 Gy), we found that the initial
176
Hf/
177
Hf ratios of lunar zircons with varied U–Pb ages are consistent with their crystallization from a KREEP-rich reservoir with a consistently low
176
Lu/
177
Hf ratio of 0.0167 that emerged ~140 My after solar system formation. The previously proposed younger model age of ~4.33 Ga for the source of mare basalts (240 My after solar system formation) might reflect the timing of a large impact. Our results demonstrate that lunar magma ocean crystallization took place while the Moon was still battered by planetary embryos and planetesimals leftover from the main stage of planetary accretion. The study of Lu–Hf model ages for samples brought back from the South Pole-Aitken basin will help to assess the lateral continuity of KREEP and further understand its significance in the early history of the Moon.
Reconciling Archean organic-rich mudrocks with low primary productivity before the Great Oxygenation Event
Authors: Lotem Noam , Rasmussen Birger , Zi Jian-Wei , Zeichner Sarah S. , Present Theodore M. , Bar-On Yinon M. , W. Fischer Woodward
Published: January 2025

The organic carbon content of ancient rocks provides a fundamental record of the biosphere on early Earth. For over 50 y, the high organic content of Archean (>2.5 Ga) mudrocks has puzzled geologists and evolutionary biologists, because high biological primary productivity was unexpected for the nascent biosphere before the rise of O
2
. Here, we took a different approach to resolve this apparent paradox, by studying the accumulation rates of Archean organic-rich mudrocks. We evaluated the sedimentation rates of three sections of the Mount McRae Shale and Jeerinah Formation (2.68 to 2.48 Ga, Pilbara Craton, Australia) with new and recently published U–Pb zircon ages from intraformational ash beds. For comparison, we compiled Phanerozoic (<500 Ma) data from comparable depositional settings and developed an idealized model that considers the sedimentation rates for predicting rock organic content. We found that organic-rich Archean mudrocks were deposited under exceptionally low sedimentation rates (~1 m/Ma), in sharp contrast to organic-rich rocks from the Phanerozoic Eon (10 to 100 m/Ma). Constrained by observations, model results indicated that the Archean data reflect low primary productivity (~100-fold lower than during the Phanerozoic) and enhanced preservation under anoxic conditions, with the principal control on organic carbon content provided by dilution with inorganic sediment. Thus, the high organic carbon content which is typically attributed to high productivity instead reflects slow accumulation, high preservation, and minimal inorganic dilution—reconciling the geological evidence with a slow carbon cycle cadence during Archean time.
Beyond EME
Authors: van den Hoven Melanie , Al Shemeili Hasan
Published: January 2025

This linguistic ethnography investigates perspectives on effective English communication of nine English-medium
graduates employed in a multicultural high-risk industry. Our collaboration as two nuclear professionals uses an interdisciplinary
approach to examine workplace communication at a joint venture involving Emirati and Korean partners in the United Arab Emirates
(UAE) where English is seen as both a problem and a solution. The study draws on etic inputs from English-medium education (EME)
discourses linking English to employability and lingua franca communication, a concern with miscommunication in
organizational studies, and workplace sociolinguistics for conceptual tools highlighting transactional goals within workplace
communication. This study uses ethnographic interviews to generate understanding of the safety basis of workplace communication in
English in a multicultural high-risk industry. The study provides practical insights for language educators on effective
communication in a high-stakes sector where safety is a topic of talk and safety informs the development of a professional variety
of nuclear English and associated communication techniques. The study highlights safe communication practices as a feature of
workplace communication in English, provides some guidance on relevant resources from aviation English, and emphasizes the need
for further collaborations between academia and industry.
A typology of alternative questions in Chinese and other East Asian languages
Authors: Li Xinyi
Published: January 2025

This paper presents a typological study of the coding strategies of alternative questions (AQs) in Chinese and its
linguistic neighbours in Asia. An AQ is a type of question in which the speaker asks the hearer to decide which of two or more
alternatives holds. Previous studies have noted that some languages use a general disjunctive conjunction to connect the
alternatives while others use an AQ-dedicated conjunction, like haishi 還是 in Mandarin. Our investigation finds that this latter kind of
conjunction is preferred in southern varieties of Chinese, while some northern Chinese dialects tend to drop the conjunction and
add a modal particle to each alternative. The divergence reflects a more general picture of AQ-type distribution across and beyond
East Asia, where languages in the north and the west with OV order prefer to add a question marker to each alternative without
using conjunctions, while languages in the east and the south with VO order prefer to use a conjunction and allow the items to be
non-question-marked. In the transition zone from OV to VO, two atypical AQ types emerge in Sinitic languages. One type uses modal
particles or the copula verb shi 是 as the connector; the other type simply juxtaposes the alternatives without any marking, or adds a modal
particle or shi 是 to each
option. With data from and beyond East Asian languages, we argue that many of the AQ-dedicated conjunctions developed from
non-assertion markers in the sentence-initial position, which is more likely to happen in VO languages.
Historical linguistics, the pronunciation of Latin and teaching of classical languages
Authors: Kavčič Jerneja , Inkret Andreja
Published: January 2025

We present attempts at reforming the pronunciation of Latin in Slovenia, also analyzing — based on a survey on the
use of pronunciation in primary and high schools — the reasons for the lack of their success. In addition, we discuss two related
pedagogical projects that involved primary and secondary pupils. Our main conclusion is that the adherence to the traditional
pronunciation makes it necessary to readdress the issue of how a more authentic way of Latin pronunciation is to be incorporated
in the language instruction. One such attempt was made during the summer school, where we informed students about findings of
modern historical linguistics concerning the phonological system of Classical Latin. In addition, we tried to adopt these findings
in practice, by following them in reading a part of an authentic Latin text. Our results show that this approach to presenting the
classical pronunciation of Latin can be an interesting and well-received part of Latin instruction.