bluuebunny/crossref_metadata_2025 huggingface dataset:
Review on 6G communication and its architecture, technologies included, challenges, security challenges and requirements, applications, with respect to AI domain
Authors: Bhide Pranita , Shetty Dhanush , Mikkili Suresh
Published: December 2024

The evolution of wireless communication systems has led to the emergence of the sixth generation (6G) communication architecture, characterised by transformative technologies and novel paradigms that transcend the capabilities of its predecessors. This paper presents an overview of the various aspects of 6G communication architecture, focusing on its technologies, challenges, and applications within the domain of artificial intelligence (AI). The abstract provides an overview of a review on 6G communication, focusing on its architecture, technologies, challenges, security concerns, and requirements within the context of the AI domain. The paper explores the evolving landscape of wireless communication, delving into the anticipated features and capabilities of 6G networks. The architecture emphasises the integration of AI‐driven elements, such as intelligent resource allocation and autonomous network management. Various technologies, including terahertz frequencies and integrated satellite networks, are discussed in terms of their potential to reshape connectivity paradigms. However, alongside the promises, a multitude of challenges arise. These encompass spectrum scarcity at terahertz frequencies, energy efficiency concerns, and the need for global standardisation. Addressing security challenges is crucial, considering the expanded attack surface and the integration of AI‐powered functionalities. The paper also delineates the stringent requirements that 6G must fulfil, spanning ultra‐low latency, high bandwidth, massive device connectivity, and reliable communication. Contextualising these discussions, the review highlights applications within the AI domain that stand to benefit from 6G advancements. These include edge AI, augmented reality, autonomous systems, and IoT‐enabled environments. By synergising cutting‐edge wireless capabilities with AI‐driven intelligence, 6G is poised to revolutionise industries and societal experiences in unprecedented ways.
Magnetometry: Solving the fundamental ambiguity from line pair inversion
Authors: Bommier Véronique
Published: December 2024

Context. All magnetic field vector measurements lead to ambiguous results.

Aims. We demonstrate that carrying out observations in two different lines belonging to the same multiplet, but with different absorption coefficients (and thus formed at two different depths, e.g., Fe I 6302.5 Å and 6301.5 Å) allow for the azimuth ambiguity remaining from the Zeeman signal interpretation to be resolved.

Methods. The measurement based on an interpretation of the Zeeman effect relates to the magnetic field, H, and not the divergence-free magnetic induction, B. We analyzed how the anisotropy of the photosphere, which is strongly stratified due to gravity and density at the star surface, affects the estimation of div H. We also considered how the ambiguity resolution ought to be performed in these conditions.

Results. We obtained two ambiguity-resolved field vector maps at two different, but nonetheless close altitudes. This allowed us to derive the current density full vector via curl H = J. The process revealed the horizontal component of the current density, which is generally found to be markedly larger than the better known vertical one. We observed some systematical trends and present some examples in this paper, such as circular currents wrapping spots clockwise about a positive polarity spot and counterclockwise about a negative polarity spot. We also detail the strong horizontal current components crossing active region neutral lines.

Conclusions. Finally, we remark that the Na I D1 and D2 lines form another such line pair. We propose them as a way to access the low chromosphere where they are formed. However, a better spatial resolution for both observations and analysis would likely be necessary in such a medium.
Differential game and coordination of a three-echelon closed-loop supply chain considering green innovation and big data marketing
Authors: Wu Zhihui , Zhang Yiran , Dong Chaoqun
Published: December 2024

In this paper, the problems of green innovation investment and coordination are investigated for a three-echelon closed-loop supply chain with Big Data services, where the considered supply chain consists of a manufacturer, a retailer and Big Data service provider. Firstly, by considering the effects of product energy efficiency level (EEL) on demand and recycling quantity, the differential game models under centralized and decentralized decision modes are established. By applying optimal control theory, both the equilibrium strategies and channel profits are solved and compared under the two modes. Then, the joint contract including a revenue-sharing contract and a bilateral cost-sharing contract is proposed to coordinate the supply chain. Finally, the impacts of key system parameters on equilibrium strategies, product EEL, brand goodwill and channel profits are discussed by numerical examples. Meanwhile, the effectiveness of the joint contract in coordinating the decentralized channel is verified. The results show that the green innovation effort, the Dig Data marketing effort, the EEL of product, the brand goodwill and channel profits under centralized decision mode are higher than those values under decentralized decision mode, but the recycling quantity is relatively low. The joint contract can coordinate three-echelon closed-loop supply chain.
Debonding Characteristic and Survival Probability of Adhesive Flash-Free Ceramic Orthodontic Brackets Following pH Cycling
Authors: Soliman Tarek Ahmed , Robaian Ali , Alqhtani Nasser Raqe , Alshehri Abdullah , Alqahtahni Abdullah Saad , Aljulayfi Ibrahim Saleh , Alazzazi Magdy , Elkaffas Ali , AlGhannam Shahad Saleh , Ghorab Sayed
Published: December 2024

Objectives Orthodontic bracket bond failure is an obstacle in clinical orthodontics. This study investigated the influence of pH cycling on the shear bond strength (SBS), adhesive remnant index (ARI), and survival probability of adhesive-precoated flash-free ceramic brackets.

Materials and Methods Forty mandibular premolars were randomly divided into two groups (n = 20): C: noncoated orthodontic brackets, and F: flash-free adhesive-precoated orthodontic brackets. Each group was subdivided into two subgroups according to storage medium solutions (n = 10): in subgroup AS, specimens were immersed in artificial saliva for 24 hours, and in Subgroup ASL, specimens were recycled between a demineralizing solution and an artificial saliva for 42 days. Within each subgroup, specimens were subjected to SBS and ARI testing. SBS data were analyzed using one-way ANOVA (analysis of variance) and Tukey's post-hoc test. Weibull analysis was performed on the SBS data to determine the characteristic SBS and their survival probabilities.

Results Flash-free adhesive-precoated brackets had higher significant (p < 0.001) SBS values in both the AS group (17.74 ± 1.74 MPa) and the ASL group (12.61 ± 1.40 MPa) compared with the noncoated bracket (10.67 ± 1.55 and 7.89 ± 1.39 MPa, respectively). The ARI scores for the noncoated brackets in the AS group were 70% occurrence for score 1, while 90% for score 1 in the ASL group. For the flash-free precoated brackets, ARI scores were 70% occurrence for score 2 in the AS group, while 80% for score 2 in the ASL group. Flash-free brackets had higher SBS in both AS and ASL groups (14.07 and 9.76 MPa, respectively), at 95% survival probability.

Conclusion Flash-free orthodontic brackets performed better in terms of significantly higher bond strength and higher ARI scores. Meanwhile, noncoated brackets revealed acceptable SBS results in both storage medium groups. Flash-free brackets showed higher survival than the noncoated brackets in both storage medium groups at 90% survival probability.
Sparganosis of the Cauda Equina: A Rare Case of Lower Thoracic Cord Edema and Diagnostic Challenges
Authors: Iampreechakul Prasert , Angsusing Chonlada , Hangsapruek Sunisa , Thammachantha Samasuk , Tanpun Adisak
Published: December 2024

Sparganosis is a rare parasitic infection caused by the larvae of Spirometra species, with spinal involvement being exceedingly uncommon. We present the case of a 46-year-old woman with progressive lower limb weakness, sensory deficits, and bowel and bladder dysfunction over a 3-month period. Initial magnetic resonance imaging revealed an abnormal intradural lesion from L2 to S2, along with thoracic spinal cord edema, raising suspicion for a spinal dural arteriovenous fistula (DAVF). After referral to our institution, further imaging ruled out DAVF, and findings suggested arachnoiditis and radiculitis of the lumbosacral nerve roots. The patient underwent a laminectomy, revealing inflamed arachnoid membranes and diffuse yellowish-whitish granulation tissue adherent to the cauda equina, which histopathological analysis confirmed as sparganosis. Postoperatively, the patient showed improved motor strength, although bowel and bladder dysfunction persisted. This case highlights the diagnostic challenges of spinal sparganosis, the need for early surgical intervention, and the importance of considering parasitic infections in endemic regions.
Insurance demand: a historical long-run perspective (1850–2020)
Authors: Kohl Sebastian , Römer Matthias
Published: December 2024

Existing research on how international insurance demand varies with income is largely driven by cross-sectional variation post-1970. Drawing on newly collected historical long-run data on life insurance premiums starting as early as 1850 to 2020 for 20 OECD countries, we evaluate the ‘S-Curve’ predicting insurance demand as each country transitions through different income levels. In contrast to predictions in the literature, we reject the ‘S-curve’, but identify a two-bump curve with two high-elasticity episodes, one driven by a massive expansion of life insurance contracts at the end of the 19th century to ensure mortality risks and the other in the late 20th century driven by a shift to savings products. This could imply that the longitudinal catching-up process of countries with low insurance density may be steeper than what the cross-sectional ‘S-Curve’ would suggest.
Description of the current–voltage characteristic of a Josephson point contact on the basis of a microbridge model
Authors: Ainitdinov Kh. A. , Malinovskii L. L.
Published: December 2024

On the basis of the microbridge model proposed by us in an earlier paper we calculate the current-voltage characteristic of a point contact and its temperature dependence. The calculated results describe the experimental data with good accuracy and this substantiates the microbridge model. In a bridge whose size is smaller than the coherence length ξ of the superconductor and the electron mean free path l the energy spectrum of excitations in the region of the voltage drop is described by the electron distribution function in the normal state. The position of the boundary of the normal region is determined by attainment of the critical current density and in the high-voltage region (heating region), by the critical temperature of the superconductor.
Thermodynamic theory of domain structures accompanying phase transitions in polarized media
Authors: Bar’yakhtar V. G. , Bogdanov A. N. , Yablonskiĭ D. A.
Published: December 2024

The thermodynamically stable domain structures in polarized media have the character of an intermediate state, associated with the first-order phase transitions induced by an external field. The thermodynamic theory of the domain structures, enabling calculation of the boundary of existence of the intermediate state, the magnetization of the samples divided into domains, and the study of the structure of the intermediate state without specifying the type of domain structure is constructed.
Thermoplastic effect in the thermal expansion of solidified gases
Authors: Aleksandrovskiĭ A. N. , Chishko K. A. , Kosobutskaya E. A. , Gavrilko V. G.
Published: December 2024

Hysteresis of the thermal expansion has been found, which disappears on thermal cycling and reappears again after holding the specimens at the measuring temperature for a long time (for 8 h). Experiments were carried out on polycrystalline argon with N2 and CO impurity (0.5−2 mole%) and also on pure polycrystalline krypton over the temperature range 2−12° K. The initial amplitude of the hysteresis (the relative increase in the thermal expansion coefficient) was about 14% in impure argon and 6% in pure krypton. The investigations were carried out for temperature cycles with different values of the temperature interval (0.2−2 °K) and with different heating (cooling) rates in the range 5·10−2−3·10−3 °K·min−1. The existence of hysteresis is associated with the possibility of the presence in the fee argon lattice of hcp phase regions near sources of internal stresses; dislocations, grain boundaries, etc. On changing the temperature, microplastic deformation takes place in the defect regions, caused by the tendency to reduce the proportion of hcp phase.
Instability of plastic flow in superconductors
Authors: Nechiporenko I. N.
Published: December 2024

We have studied the process of localized plastic deformation of superconductors; criteria have been found for plastic flow instability (stepwise flow) of crystals containing dislocations surmounting barriers by a thermal fluctuation mechanism. It is shown that, depending on the parameters of the superconducting transition at temperatures T < Tc, the unstable plastic flow stress in the crystals in the superconducting and normal phases have one or two intersection points (or none).
Ground state and ordering of a quantum crystal in the case of a pseudospin S = 1
Authors: Kovarskiĭ V. L. , Sukharevskiĭ B. Ya.
Published: December 2024

The structure of the ground state of a pseudospin system was studied in the molecular-field approximation taking into account tunneling. The case of a potential with three minima, corresponding to the pseudospin S = 1, and ferrodistortional ordering was studied. A first-order phase transition between the ordered and disordered phases at T = 0 was found. The possibility of the formation of a partially ordered antiisostructural phase, associated with tunneling, was studied. It was established that in the cases studied such a phase does not exist.
Hindered rotation of linear molecules in atomic cryocrystals and the thermal properties of solutions
Authors: Manzheliĭ V. G. , Kosobutskaya E. A. , Sumarokov V. V. , Aleksandrovskiĭ A. N. , Freĭman Yu. A. , Popov V. A. , Konstantinov V. A.
Published: December 2024

The heat capacity and thermal expansion of Ar and Kr crystals as well as of the solid solutions of nitrogen isotopes based on them are studied in the temperature range 2−12 K. The impurity concentration varied from 0.5 to 2 mole %. The study of the system revealed an anomalous behavior of the thermal properties of the solutions owing to the unhindering of the rotational degrees of freedom of the impurity molecules. The results obtained are interpreted on the basis of the Devonshire–Manz–Mirsky (DMM) model. The barriers hindering the rotation of impurity molecules in Ar and Kr matrices are determined. It is predicted that a low-temperature peak exists in the heat capacity of the solutions with maxima in the region T < 1 K and that the coefficient of thermal expansion is negative below 1 K.
Infrared lattice absorption of α-nitrogen cryocrystals at 3−25 °K
Authors: Fugol’ I. Ya. , Khashchina L. V. , Pritula I. M.
Published: December 2024

IR absorption spectra of the α phase of N214 in the temperature range 3−25 °K at frequencies from 5 to 110 cm −1, as well as of the isotope N215 in the range 25−110 cm−1 at 7 °K have been investigated. The influence of defects and impurities on the spectrum was studied. The presence of two-phonon combinational frequencies, the existence of forbidden one-phonon maxima, the presence of a non-monotonic continuum in the spectrum were established. The nature of multiphonon interactions observed in the far IR spectra of α-N2, particularly the role of optic anharmonicity, is discussed.
Effect of the Dzyaloshinskiĭ interaction on the intermediate state of rhombic antiferromagnets
Authors: Gorobets Yu. I. , Medvedovskaya O. G. , Chepurnykh G. K.
Published: December 2024

The intermediate state (IS) of orthoferrite in the spin-flop transition field Ht(T) is studied taking into account the Dzyaloshinskiĭ interaction. It is shown that as the transition field decreases [Ht (T) → 0 in the limit T → TM] the dimensions of the IS domains increase, and in a field Ht(T) ≪ 2d (d is the Dzyaloshinskiĭ constant) the IS studied does not exist.
Temperature dependence of superradiance in a pyrene-doped diphenyl crystal in the temperature range from 1.5 to 60° K
Authors: Zinov’ev P. V. , Malyukin Yu. V. , Naboĭkin Yu. V. , Rudenko E. N. , Samartsev V. V. , Silaeva N. B.
Published: December 2024

Experimental studies of the temperature dependence of the intensity and spectrum of optical superradiance in a pyrene-doped diphenyl crystal have been conducted in order to examine optical phase relaxation in solids. This is the first attempt to investigate relaxation processes in doped molecular crystals. Possible mechanisms that would account for the observed effects are proposed.
Thermal-electric self-oscillations in metals with a negative differential conductivity
Authors: Kadigrobov A. M. , Tzyan (Chiang) Yu. N. , Logvinov I. I.
Published: December 2024

It is shown that thermal-electric self-oscillations (TESO) can be genrerated in normal metals with a negative differential conductivity. Data on the first observation of such self-oscillations in indium are presented along with the results of calculation of the specific heat of the metal on the basis of the self-oscillation parameters.
Superconducting and magnetic properties of lanthanum monosulfide
Authors: Ikorskiĭ V. N. , Matizen É. V. , Moiseenko V. A. , Starikov M. A.
Published: December 2024

The initial region of the H–T phase diagram and the magnetic susceptibility of a single-crystal lanthanum monosulfide sample have been studied. The values of its superconducting parameters are used to determine the electron density of states at the Fermi level, which proves to be considerably smaller than that of metallic lanthanum. The density of states calculated from the experimental magnetic susceptibility data in agreement with that estimated from H–T phase diagram measurements.
Magnetic phase diagram of neodymium monosulfide
Authors: Makarov V. I. , Kleiner V. Z. , Tereshina N. S. , Fisenko V. A.
Published: December 2024

The magnetic properties of an antiferromagnetic NdS single crystal in magnetic fields up to 11 T were studied. It is shown that the H−T phase diagram contains a tricritical point, separating the region of first- and second-order phase transitions.
Inelastic interaction of domain boundaries and relaxation of magnetic solitons in a biaxial ferromagnet
Authors: Kivshar’ Yu. S. , Kosevich A. M.
Published: December 2024

We derive the threshold value of the external magnetic field below which there takes place an annihilation of two Walker domain boundaries of opposite polarization, accompanied by the formation of a damped magnetic soliton.
Acoustic properties of nonequilibrium superconductors with fine structure in the electronic density of states
Authors: Balankin A. S. , Kashurnikov V. A.
Published: December 2024

We have studied the influence of fine structure in the electronic spectrum on the absorption of longitudinal and transverse phonons of frequency Ω (Ω < δ; δ < Ω < 2 Δ; and 2 Δ ≪ Ω) in nonequilibrium superconductors under the influence of various forms of narrow pumping (δ = ω—2Δ ≪ Δ). It is found that account of the fine structure in the electronic density of states N0 (ξ) leads to a significant change in the frequency dependence of the absorption coefficients and to the possibility of achieving a regime of quantum generation of transverse ultrasound (Ω ≳ 2 Δ).
Critical current in superconducting niobium films with different grain sizes
Authors: Ichkitidze L. P. , Bablidze R. A. , Kuznetsov V. P. , Skobelkin V. I.
Published: December 2024

The critical current density jc is studied in a perpendicular magnetic field in niobium films with different grain sizes r. It is shown that jc reaches a maximum value in the temperature range 4.2 K ≤ T ≲ 0.8 Tc and for reduced magnetic fields 0.2 ≲ h ≲ 0.8 with commensurate values of r and coherence length ξ. In the case r > ξ the critical current density decreases as the grain-size increases.
Specific heat of a quantum crystal with impurities
Authors: Tsymbalenko V. L.
Published: December 2024

It is shown that the impurity atmosphere of dislocations in quantum crystals makes a contribution to the specific heat with a magnitude comparable with the phonon specific heat. An experimental procedure is discussed.
Detection of a nonmonotonic frequency dependence of electric-field penetration into a superconductor
Authors: Dmitriev V. M. , Zolochevskiĭ I. V. , Khristenko E. V.
Published: December 2024

The paper reports the first observation of a nonmonotonic frequency dependence of the de resistance of discrete resistive states that are induced in a superconducting channel by an external electromagnetic field.
Low-temperature creep of crystalline methane
Authors: Romanusha V. A. , Leont’eva A. V. , Prokhorov A. Yu.
Published: December 2024

The creep of crystalline methane was studied at temperatures from 4.2 to 30° K. Anomalies were found in the rate of stationary creep and in the activation energy close to the phase transition temperature.
Destruction and restoration of the superconducting state in niobium films by transport-current pulses
Authors: Vendik O. G. , Zaionchkovskii A. Ya. , Kolesov S. G. , Krasikov S. B. , Pakhomov O. V. , Ruban A. S.
Published: December 2024

The time-dependent characteristics of the destruction of superconductivity in wide niobium films by current pulses and the restoration of the superconducting state after the current is switched off are studied experimentally. A procedure is proposed for studying the switching from the superconducting state into the normal state and back again using the results of measurements of the decay of the microwave signal in the transmission line based on a superconducting film as a function of time. It is shown that the time for destroying the superconducting state equals the formation time of the normal transverse strip plus the heating time of the entire film heated by the current up to the critical temperature. The dependences of the characteristic times on the supercriticality of the current, the duration of the current pulse, and the thermophysical parameters of the substrate are studied.
Geometric resonance anomalies due to the generalized topological transition
Authors: Kaganov M. I. , Lisovskaya T. Yu. , Nurmagambetov A. A.
Published: December 2024

A geometric definition of the generalized topological transition (GTT) is given. The sound absorption coefficient under conditions of geometric (Pippard) resonance, with the formation of a crater on the Fermi surface (FS), is calculated, and it is shown that the GTT is accompanied by an increase in the sound absorption coefficient and also by a significant increase in the complexity of the oscillator dependence, in particular, giant oscillations in the sound absorption should be observed as the magnetic field is varied.
Peculiarities of the current–voltage characteristics of superconducting niobium films in a mixed state
Authors: Prokhorov V. G. , Kaminskiĭ G. G. , Tret’yachenko K. G. , Pan V. M.
Published: December 2024

The current–voltage characteristics and their first derivatives for niobium thin films of different thickness were recorded over a wide range of magnetic fields. It is shown that the nonlinear behavior of the initial sections of the current–voltage characteristics of the films studied is determined by the interaction of a moving magnetic flux with pinning centers. A peak, characterizing the dynamic transition of the vortex ensemble from an incoherent flow to a viscous (coherent) flow, was discovered on the dV/dI curves for some values of the current I*. A theoretical model, qualitatively explaining the experimental results, is proposed.
Detection of the paraconductivity anisotropy of two-dimensional superconductors in magnetic field
Authors: Dmitrenko I. M. , Fogel’ N. Ya. , Cherkasova V. G.
Published: December 2024

The excess conductivity σ′ has been found to be anisotropic in the fluctuation region near the phase-transition line Tc(H) in thin films of transition metals. It has been established that when the magnetic field H and the current I are parallel the value of σ′ is greater than for the H ⊥ I orientation (in both cases the field is parallel to the surface of the film). The anisotropy is due to the nonisotropy of the energy fluctuation spectrum of the order parameter. It depends essentially on the ratio of the film thickness d to the coherence length ξ (T) and reaches its maximum in the region of the field at which a single chain of vortices enters the film, i.e., at d ≈ 2ξ(T). Our experimental data are in qualitative agreement with the results of fluctuation theory for the film in a parallel field.
Magnon bound states in an anisotropic spin chain with Dzyaloshinskii interaction
Authors: Krivoruchko V. N.
Published: December 2024

The wave functions and energies of bound states of an arbitrary number of magnons in a chain with s = 1/2 spins with an anisotropic exchange interaction and a nonuniform exchange-relativistic interaction of the Dzyaloshinskii type are found. The cases of effective anisotropy of the easy-axis and easy-plane types are studied. It is shown that the Dzyaloshinskii interaction substantially affects the dependence of the wave function on the quasimomentum.
Mutual annihilation of triplet excitons in the spin-polarized state
Authors: Avdeenko A. A. , Levitskii I. A. , Naboikin Yu. V.
Published: December 2024

The distinctive features of the mutual annihilation of triplet excitons with a zero projection of the spin onto the direction of an external magnetic field (from 3.5 to 6 T) applied along the monoclinic axis are investigated in 4,4′-dichlorobenzophenone single crystals at a temperature of 2°K. An analysis of the possible relaxation processes in the exciton triplet and in the exciton pair complex shows that the nonmonotonic field dependence of the annihilation rate constant is attributable to nonphonon spin–lattice relaxation processes in the pair complex.
Nonequilibrium dynamic quasiparticle distributions in superconducting films in a strong high-frequency field
Authors: Azovskiĭ A. Yu. , Bezuglyĭ E. V.
Published: December 2024

The quasiclassical equations of the nonlinear kinetics of superconducting alloys, describing the heating deformation of the dynamic distribution function of electronic excitations under the action of microwave pumping, are derived taking into account the oscillations in the density of states and the limit of the energy spectrum of the superconductor in an alternating electromagnetic field. The form of dynamic nonequilibrium distributions arising in a superconducting film at low temperatures T ≪ Δ is determined; the nonlinear electromagnetic absorption owing to the entrainment of excitations by oscillations of the energy levels and the direct absorption of photons by quasiparticles are calculated.
Role of local features of the Fermi surface in galvanomagnetic properties of tungsten at low temperatures
Authors: Volkenshtein N. V. , Dyakina V. P. , Startsev V. E. , Cherepanov A. N. , Cherepanov V. I. , Glinski M.
Published: December 2024

The anisotropy, magnetic-field, and temperature dependences of the transverse magnetoresistance and Hall coefficient in tungsten single crystals with ρ273.2/ρ4.2 up to 112,000 were measured over the temperature range from 1.5−130 K and over the magnetic field range from 2 to 150 kOe. Near 27 K sharp maxima in the temperature dependence of the Hall coefficient and strong deviations from Kohler’s rule were observed. It was found that these anomalies were sensitive to magnetic field orientation relative to the crystallographic directions and to the presence of impurities and dislocations. The anomalous behavior of the galvanomagnetic properties that was found is explained by the anisotropy of the electron–phonon scattering, caused by intersheet scattering of electrons by phonons between the closed sheets Γ4e (electron jack) and H3h (hole octahedron) in the regions of closest approach of these sheets in the ΓH direction of the Brillouin zone.
Equilibrium states and spectrum of precession excitations of incommensurate antiferromagnetic structure
Authors: Chupis I. E.
Published: December 2024

The equilibrium states of a modulated antiferromagnetic structure, for which there is no Lifshitz invariant, in a magnetic field with modulation axis and the orientation of the field lying in the plane of the spiral are studied. The phase diagram of the states in the magnetic-field–temperature plane is constructed and it is shown that a tetracritical point of second-order phase transitions exists. The spectrum of precession excitations, whose characteristic feature is the presence of frequency branches with anomalous dispersion of the phason type, is obtained.
Phonon relaxation of kink-type solitons in quasi-one-dimensional ordered systems
Authors: Ivanov B. A. , Tartakovskaya E. V.
Published: December 2024

The interaction of the order parameter of a one-dimensional nonlinear system with elastic excitations of a three-dimensional matrix is investigated. The kinetic coefficients of the “kink gas” are calculated in the flexible-chain and rigid-chain approximations for two models of the nonlinear system (sine–Gordon and Φ(4)). The contribution of phonon processes in the relaxation of the system to an equilibrium state is analyzed, and the temperature dependence of the kinetic coefficients of the kink gas is determined.
Jahn-Teller glassy crystals
Authors: Boĭko F. A. , Bochkovaya G. Yu. , Bykov A. M. , Ksenofontov V. G. , Ruban I. V. , Sukharevskii B. Ya.
Published: December 2024

Using adiabatic calorimetry and the Mössbauer effect, we show for the first time that a “glass-liquid” transition is possible in a Jahn–Teller crystal. The transition is accompanied by low-frequency oscillations that are probably characteristic of glassy transitions in a broad class of substances.
Elastic characteristics of KDy(MoO4)2 in the region of the structural transformation
Authors: Vitebskiĭ I. M. , Zherlitsyn S. V. , Zvyagin A. I. , Stepanov A. A. , Fil’ V. D.
Published: December 2024

Sound velocities in KDy(MoO4)2 were measured in the frequency range 50−120 Mhz in the temperature range 0.4−30° K that includes the structural phase transformation (SPT) point. On the basis of our data we conclude that the SPT in KDy(MoO4)2 involves multiplication of the unit cell.
Investigation of the motion of the interphase magnetic domain boundary in DyFeO3
Authors: Gnatchenko S. L. , Kharchenko N. F. , Chizhik A. B. , Eremenko V. V. , Shimchak R.
Published: December 2024

The field-dependence of the velocity of steady-state motion of an interphase magnetic domain wall in dysprosium orthoferrite is studied. Characteristic features of the motion of the interphase wall were observed: increase in the differential mobility accompanying an increase in the intensity of the driving field and asymmetry of the field-dependence of the velocity of the wall relative to the phase-transition field. It is shown that these features of the dynamics of the interphase wall are linked with the expansion of the wall when the applied field is different from the phase-transition field. The field-dependence of the velocity of the interphase wall is calculated based on a model which takes into account the transformation of the interphase wall, and the results are in qualitative agreement with experiment.
Low-temperature specific heat of TIFeS2
Authors: Aldzhanov M. A. , Guseĩnov N. G. , Mamedov Z. N.
Published: December 2024

The specific heat of the layered chain compound TlFeS2 has been measured over the temperature range 4.2−300° K. The results obtained have been analyzed with the help of the theory of the specific heat of strongly anisotropic structures.
Temperature dependence of the critical angle of the spin-flop transition in (C2H5NH3)2CuCl4
Authors: Zhuravlev A. V. , Telepa V. T.
Published: December 2024

The critical angle of the spin-flop transition (3.1° at T = 0) is determined in the rhombic antiferromagnet (C2H5NH3)2CuC14 (TN = 10.2 K), and its temperature dependence in the interval 1.7−10 K is studied. It is established that ψcr decreases monotonically as the temperature increases. A new procedure is proposed for determining the critical angle.
Superconductivity of anisotropic superstructures
Authors: Shapiro B. Ya.
Published: December 2024

The dependence of the critical temperature and the upper critical magnetic field on the degree of anisotropy of the electron dispersion law for metallic superstructures is studied. It is predicted that the proximity effect in such structures is suppressed. It is shown that the dimensional behavior of the critical magnetic field, parallel to the layers, changes as a function of the temperature and anisotropy of the electron dispersion law.
Equilibrium fluctuations in short superconducting contacts taking into account the finiteness of the energy relaxation time
Authors: Nagaev K. É.
Published: December 2024

The equilibrium fluctuations of the current and voltage in short superconducting point contacts are studied taking into account the fluctuations in the the energy distribution of the quasiparticles. The spectral density of current fluctuations in a superconducting ring, closed by a point superconducting contact, with an arbitrary quasiparticle energy relaxation time and the generation linewidth of short point contacts in the limit of short energy relaxation time are found. In this limit, taking into account the finiteness of the energy relaxation time leads to a reduction of the line-width.
Relaxation temperature-electric self-excited oscillations in inductively heated conductors
Authors: Tszyan Yu. N. , Logvinov I. I. , Kadigrobov A. M.
Published: December 2024

The conditions for excitation of temperature-electric, relaxational, self-excited oscillations in metallic conductors, whose negative differential conductivity is obtained by pumping the samples with an alternating current, are formulated. Data from the experimental observation of self-excited oscillations in an inductively heated aluminum sample, whose frequency could be increased by two orders of magnitude compared with the frequency of the self-excited oscillations excited by a de current, are presented.
Multiparameter optical fiber sensing for energy infrastructure through nanoscale light–matter interactions: From hardware to software, science to commercial opportunities
Authors: Su Yang-Duan , Ohodnicki Paul R. , Wuenschell Jeffrey K. , Lalam Nageswara , Sarcinelli Enrico , Buric Michael P. , Wright Ruishu
Published: December 2024

Monitoring of energy infrastructure through robust yet economical sensing platforms is becoming an area of increased importance, with ubiquitous applications including the electrical grid, natural gas and oil transportation pipelines, H2 infrastructure (storage and transportation), carbon storage, power generation, and subsurface environments. Plasmonic and functional nanomaterial enabled fiber optic sensors show excellent promise for a wide range of sensing applications due to their versatility to be engineered for specific analytes of interest while retaining inherent advantages of the optical fiber sensor platform. Through the design of novel sensing layers, the optical transduction mechanism and wavelength dependence can also be tailored for ease of integration with low-cost interrogation systems enabling an inexpensive yet highly functional optical fiber sensing platform. In addition, recent advances in artificial intelligence and machine learning theoretical methods have been leveraged to simultaneously extract multiple parameters through multi-wavelength interrogation such that unique wavelengths can also serve as unique sensing elements, analogous to electronic nose sensor technologies. The concept of an optical fiber based “photonic nose” via multiple interrogation wavelengths and/or sensor nodes offers a compelling platform technology to realize multiparameter speciation of chemical analytes within complex gas mixtures. In this Perspective, we further generalize the notion of multiparameter sensing through the novel “photonic nervous system” concept based upon low-cost, functionalized optical fiber sensor probes monitoring a variety of distinct analyte classes (physical, chemical, electromagnetic, etc.) simultaneously to provide broad situational awareness via integrated sensors.
Anisotropic interactions for continuum modeling of protein–membrane systems
Authors: Oppelstrup T. , Stanton L. G. , Tempkin J. O. B. , Ozturk T. N. , Ingólfsson H. I. , Carpenter T. S.
Published: December 2024

In this work, a model for anisotropic interactions between proteins and cellular membranes is proposed for large-scale continuum simulations. The framework of the model is based on dynamic density functional theory, which provides a formalism to describe the lipid densities within the membrane as continuum fields while still maintaining the fidelity of the underlying molecular interactions. Within this framework, we extend recent results to include the anisotropic effects of protein–lipid interactions. As applications, we consider two membrane proteins of biological interest: a RAS–RAF complex tethered to the membrane and a membrane embedded G protein-coupled receptor. A strong qualitative and quantitative agreement is found between the numerical results and the corresponding molecular dynamics simulations. Combining the scope of continuum level simulations with the details from molecular level particle simulations enables research into protein–membrane behaviors at a more biologically relevant scale, which crucially can also be accessed via experiment.
Series expansion of a scalable Hermitian excitonic renormalization method
Authors: Bauer Marco , Dreuw Andreas , Dutoi Anthony D.
Published: December 2024

Utilizing the sparsity of the electronic structure problem, fragmentation methods have been researched for decades with great success, pushing the limits of ab initio quantum chemistry ever further. Recently, this set of methods has been expanded to include a fundamentally different approach called excitonic renormalization, providing promising initial results. It builds a supersystem Hamiltonian in a second-quantized-like representation from transition-density tensors of isolated fragments, contracted with biorthogonalized molecular integrals. This makes the method fully modular in terms of the quantum chemical methods applied to each fragment and enables massive truncation of the state-space required. Proof-of-principle tests have previously shown that an excitonically renormalized Hamiltonian can efficiently scale to hundreds of fragments, but the ad hoc approach to building the Hamiltonian was not scalable to larger fragments. On the other hand, initial tests of the originally proposed modular Hamiltonian build, presented here, show the accuracy to be poor on account of its non-Hermitian character. In this study, we bridge the gap between these with an operator expansion that is shown to converge rapidly, tending toward a Hermitian Hamiltonian while retaining the modularity, yielding an accurate, scalable method. The accuracy is tested here for a beryllium dimer. At distances near equilibrium and longer, the zeroth-order method is comparable to coupled-cluster singles, doubles, and perturbative triples and the first-order method is comparable to full configuration interaction (FCI). The second-order method agrees with FCI for distances well up the inner repulsive wall of the potential. Deviations occurring at shorter bond distances are discussed along with approaches to scaling to larger fragments.
Spectroscopic study of energy transfer in collisions between vibrational excited H2 and CO2
Authors: Qin Chu , Zhao Xiaofang , Wang Shuying , Shen Yifan
Published: December 2024

The collisional energy transfer between vibrational excited H2(1, 7) and CO2 was investigated by exciting H2 to a vibrational excited state of v = 1, J = 7 by the stimulated Raman scattering technique. The coherent anti-Stokes Raman spectroscopy (CARS) technique determined that H2 was excited to the H2(1, 7) state. Varying the cuvette temperature, the number of H2(1, 7) particles was found to increase with the increase in H2 molar ratio α by scanning the intensity of the CARS spectrum, with peaks at different α at a temperature of 363 ± 15 K, but the peak temperature was not sensitive to α. Scanning CARS spectra after H2 collisions yielded that the energies of the excited states of H2 were mainly distributed in the vibrational and translational states, proving that the collisions between the excited states of H2 were linear collisions. The collisional transfer rate coefficients of H2(1, 7) and CO2 were obtained by fitting the Stern–Volmer equation as kv(H2) = (2.89 ± 0.30) × 10−13 cm3 s−1 and kv(CO2) = (8.23 ± 0.42) × 10−13 cm3 s−1. Exciting H2 to different states, it was found that the collisional transfer rate coefficient of CO2 was less affected by the energy of the vibrational excited H2. The rotational temperature was obtained from the Boltzmann distribution of the rotational dynamics, and it was found that the rotational temperature of CO2(0000, J) was about 3.4 times higher than that of CO2(0001, J), which proved that the energy of the vibrational excited H2 was mainly allocated to the higher rotational state of CO2(0000).
Predicting gene sequences with AI to study codon usage patterns
Authors: Sidi Tomer , Bahiri-Elitzur Shir , Tuller Tamir , Kolodny Rachel
Published: December 2024

Selective pressure acts on the codon use, optimizing multiple, overlapping signals that are only partially understood. We trained AI models to predict codons given their amino acid sequence in the eukaryotes
Saccharomyces cerevisiae
and
Schizosaccharomyces pombe
and the bacteria
Escherichia coli
and
Bacillus subtilis
to study the extent to which we can learn patterns in naturally occurring codons to improve predictions. We trained our models on a subset of the proteins and evaluated their predictions on large, separate sets of proteins of varying lengths and expression levels. Our models significantly outperformed naïve frequency-based approaches, demonstrating that there are learnable dependencies in evolutionary-selected codon usage. The prediction accuracy advantage of our models is greater for highly expressed genes and is greater in bacteria than eukaryotes, supporting the hypothesis that there is a monotonic relationship between selective pressure for complex codon patterns and effective population size. In
S
.
cerevisiae
and bacteria, our models were more accurate for longer proteins, suggesting that the learned patterns may be related to cotranslational folding. Gene functionality and conservation were also important determinants that affect the performance of our models. Finally, we showed that using information encoded in homologous proteins has only a minor effect on prediction accuracy, perhaps due to complex codon-usage codes in genes undergoing rapid evolution. Our study employing contemporary AI methods offers a unique perspective and a deep-learning-based prediction tool for evolutionary-selected codons. We hope that these can be useful to optimize codon usage in endogenous and heterologous proteins.
X*Y females exhibit steeper reproductive senescence in the African pygmy mouse
Authors: Lemaître Jean-François , Voituron Yann , Herpe Léa , Veyrunes Frédéric
Published: December 2024

A wave of studies has recently emphasized the influence of sex chromosomes on both lifespan and actuarial senescence patterns across vertebrates and invertebrates. Basically, the heterogametic sex (XY males in XX/XY systems or ZW females in ZW/ZZ systems) typically displays a lower lifespan and a steeper rate of actuarial senescence than the homogametic sex. However, whether these effects extend to the senescence patterns of other phenotypic traits or physiological functions is yet to be determined. Here, we investigated whether sex chromosomes modulate reproductive senescence using females from the African pygmy mouse (
Mus minutoides
). This biological model exhibits an odd sex determining system with a third, feminizing sex chromosome, X*, resulting in three distinct female genotypes (XX, X*X, or X*Y) that coexist in natural populations. We found that the rate of senescence in litter size at birth is much more pronounced in heterogametic X*Y females than in homogametic XX or X*X females that may support the unguarded X or toxic Y hypotheses and can be directly linked to the complex and unique X*Y phenotype. A decrease in neonatal survival with mother’s age has also been found, but this decline is not different between the three female genotypes.
Higher-order transient structures and the principle of dynamic connectivity in membrane signaling
Authors: Zhang Yuxi , MacKinnon Roderick
Published: December 2024

We examine the role of higher-order transient structures (HOTS) in M2R regulation of GIRK channels. Electron microscopic membrane protein location maps show that both proteins form HOTS that exhibit a statistical bias to be near each other. Theoretical calculations and electrophysiological measurements suggest that channel activity is isolated near larger M2R HOTS. By invoking weak interactions that permit transient binding of M2R to M2R and GIRK to GIRK (
i-i
interactions) and M2R to GIRK (
i-j
interactions), the distribution patterns and electrophysiological properties of HL-1 cells are replicated in a reaction-diffusion simulation. We propose the principle of dynamic connectivity to explain communication between protein components of a membrane signaling pathway. Dynamic connectivity is mediated by weak, transient interactions between proteins. HOTS created by weak
i-i
interactions, and statistical biases created by weak
i-j
interactions promoted by the multivalence of HOTS, are the key elements of dynamic connectivity.
SARS-CoV-2 NSP3/4 control formation of replication organelle and recruitment of RNA polymerase NSP12
Authors: Yang Jinping , Tian Buyun , Wang Pei , Chen Rongrong , Xiao Ke , Long Xubing , Zheng Xinyue , Zhu Yun , Sun Fei , Shi Yongxia , Jiu Yaming , Ji Wei , Xue Yanhong , Xu Tao , Li Zonghong
Published: December 2024

β-coronavirus rearranges the host cellular membranes to form double-membrane vesicles (DMVs) via NSP3/4, which anchor replication–transcription complexes (RTCs), thereby constituting the replication organelles (ROs). However, the impact of specific domains within NSP3/4 on DMV formation and RO assembly remains largely unknown. By using cryogenic-correlated light and electron microscopy (cryo-CLEM), we discovered that the N-terminal and C-terminal domains (NTD and CTD) of SARS-CoV-2 NSP3 are essential for DMV formation. Nevertheless, the CTD of NSP4 is not essential for DMV formation but regulates the DMV numbers. Additionally, the NTD of NSP3 is required for recruiting the RTC component to the cytosolic face of DMVs through direct interaction with NSP12 to assemble ROs. Furthermore, we observed that the size of NSP3/4-induced DMVs is smaller than virus-induced DMVs and established that RTC-mediated synthesis of double-stranded RNA (dsRNA) cargo plays a crucial role in determining DMV size. Collectively, our findings reveal that β-coronaviruses exploit the NSP3/4/12 axis to establish the viral ROs.