bluuebunny/crossref_metadata_2025 huggingface dataset:
An activation-based high throughput screen identifies caspase-10 inhibitors
Authors: Castellón José O. , Yuen Constance , Han Brandon , Andrews Katrina H. , Ofori Samuel , Julio Ashley R. , Boatner Lisa M. , Palafox Maria F. , Perumal Nithesh , Damoiseaux Robert , Backus Keriann M.
Published: February 2025

An activation-based high throughput screening platform enables inhibitor discovery for procaspase-10.
A σ,π-type monocarborane copper acetylide for regioselective 1,4-disubstituted 1,2,3-triazoles
Authors: Zhang Kang , Feng Luting , Jin Yujie , Liu Jiyong , Duttwyler Simon
Published: February 2025

This work presents the first σ,π-bis(copper) acetylide-enabled 1,4-disubstituted 1,2,3-triazolylated monocarborane derivatives with excellent yields via CuAAC under mild conditions.
Carbon quantum dots modified with hyperbranched polyglycerol for bioapplications: improved photostability and temperature selectivity
Authors: Sotoma Shingo , Shiraya Kota , Shimomura Suzune , Yoshida Yumi , Maeda Kohji
Published: February 2025

Surface modification of carbon quantum dots with hyperbranched polyglycerol improved their photostability and enhanced their selectivity to temperature as a nanothermometer.
Fast and effective preparation of highly cytotoxic hybrid molecules of schweinfurthin E and OSW-1
Authors: Schelle Baptiste , Fargier Jules , Grisel Clément , Askenatzis Laurie , Gallard Jean-François , Desrat Sandy , Bignon Jérome , Roussi Fanny , Norsikian Stéphanie
Published: February 2025

The first synthesis of hybrid molecules that combine the pharmacophores of two natural compounds: schweinfurthin E (SW-E) and the glycosidic moiety of OSW-1 has been developped.
5G‐coded fluid antenna multiple access over block fading channels
Authors: Hong Hanjiang , Wong Kai‐Kit , Tong Kin‐Fai , Xu Hao , Li Haoyang
Published: February 2025

Fluid antenna multiple access (FAMA) is a concept capable of massive connectivity on the same physical channel without the need of precoding or interference cancellation, by exploiting a super‐high dimensional received signal in the spatial domain from fluid antenna system (FAS). This letter investigates the use of 5G New Radio (NR) Modulation Coding Scheme (MCS) for FAMA systems to improve its connectivity over block fading channels. In particular, an iterative decoding receiver with iterative interference covariance estimation is proposed, designed explicitly for slow fading channels. Extrinsic information transfer (EXIT) chart is used to analyze the performance of the proposed iterative receiver. Both EXIT chart analysis and numerical results indicate that the proposed receiver outperforms the existing approach that uses fixed covariance in block fading channels. Also, the results indicate that coded FAMA can serve 100 user terminals (UTs) at the rate of 0.5 bit/s/Hz under rich scattering.
High importance feature selection and DV‐OSR‐QSED strategy for open‐set recognition
Authors: Xu Tong
Published: February 2025

A significant challenge in the domain of anti‐drone warfare is the identification of enemies or own aircraft through the analysis of data broadcast by drones (e.g. ADS‐B). This issue can be conceptualized as an open set recognition (OSR) problem. This paper proposes a DV‐OSR‐QSED framework for the purpose of data visualization‐based OSR (DV‐OSR). Phase‐based 2D high‐importance features are extracted, the DV‐OSR framework is designed and mapped to 2D, and the 5th and 95th quantile selection‐Euclidean distance (QSED) strategy is proposed. Experiments show that by using the proposed framework, the correct classification rate for known and unknown samples is 96.04% and 95.79%, the recall rate and F1 value are 89.00% and 92.27%, and the AUC is 0.9630.
Analysis of broadband oscillation mechanisms in grid‐forming and grid‐following converters based on virtual synchronous generator
Authors: Wang Weiming , Liu Zhijian , Lou Jun , Cheng Cheng , Song Qi , Shi Yaoting
Published: February 2025

Aiming at the problem of increased complexity in broadband oscillations caused by the introduction of virtual synchronous generator (VSG) control to grid‐forming and grid‐following grid‐connected converters interacting with inductive weak grids, positive and negative sequence impedance of such converters is established under small perturbations in phase angle and voltage using harmonic linearization. The impact of various control links on the broadband impedance characteristics associated with different control strategies is then analysed. It is observed that the grid‐forming converter equipped with VSG demonstrates lower impedance magnitude and inductive behaviour in the medium‐to‐high frequency range, thus emulating the external behaviour of a synchronous generator more accurately. Furthermore, the analysis based on the maximum peak Nyquist stability criterion reveals that voltage control and current‐type VSG lack phase margin, leading to potential oscillation risks within their respective dominant frequency bands. Finally, the validity of the broadband oscillation mechanism analysis is confirmed through hardware‐in‐loop experiments and impedance sweep analyses.
Nanoparticle‐enhanced dielectric oils for improved electrical insulation: Comparison of MgO, Al2O3, and SiO2‐based dielectric nanofluids
Authors: Karataş Mehmet , Biçen Yunus
Published: February 2025

This study provides comprehensive and quantitative assessments of the electrical insulation, viscosity, thermal conductivity, flash point, acidity, and stability of dielectric nanofluids. In the experiment, naphthenic mineral oil was chosen as the base fluid. MgO, Al2O3, and SiO2 were preferred as nanoparticles. In the dielectric breakdown voltage (BDV) tests performed, increased values were observed at certain concentrations for each nanofluid, with the highest value in the SiO2‐based nanofluid being 83.47 kV at a concentration rate of 0.05 g/L. Adding nanoparticles to the base oil increased the viscosity of all suspensions. Except for MgO‐based dielectric nanofluid, the flash points of other nanofluids increased as compared to pure oil. Total acid number (TAN) values, on the other hand, increased for SiO2‐ and Al2O3‐based nanofluids but decreased for MgO‐based nanofluids. However, all values are quite below the standard limit of 0.25 mgKOH/g. The percentage transmittance values calculated from the ultraviolet and visible light (UV–vis) spectrophotometry results differed for each nanofluid. However, they were all lower than the base oil. In general, the results indicate that the use of dielectric nanofluids in electrical systems will be beneficial, provided that the problem of long‐term stabilisation is solved.
Moving target detection based on improved Gaussian mixture model in dynamic and complex environments
Authors: Li Jiaxin , Duan Fajie , Fu Xiao , Niu Guangyue , Wang Rui , Zheng Hao
Published: February 2025

Recently, background modeling has garnered significant attention for motion target detection in vision and image applications. However, most methods do not achieve satisfactory results because of the influence of background dynamics and other factors. The Gaussian mixture model (GMM) background modeling method is a popular and powerful motion background modeling technology owing to its ability to balance robustness and real‐time constraints in various practical environments. However, when the background is complex and the target moves slowly, the traditional GMM cannot accurately detect the target and is prone to misjudging the moving background as a moving target. To address the interference from complex backgrounds, this study proposes a target detection method that combines an adaptive GMM with an improved three‐frame difference method, along with an algorithm that combines grayscale statistics with an improved Phong illumination model for illumination compensation and shadow removal. The experimental results demonstrate that the improved method has better robustness, improves target detection accuracy, and reduces noise and background interference.
A pointer scheduling algorithm for radar device‐to‐device opportunistic communication based on Tabu strategy
Authors: Tian Gang , Pan Zhiwen , Xing Wenge
Published: February 2025

Existing integration of radar detection and communication (IDAC) systems are in general based on multi‐input multi‐output multi‐stations or single‐base transceiver splitting. However, these methods are challenging to realise IDAC for integrated receive‐transmit half‐duplex (IRTHD) pulse radars, which are detection‐centric and are based on self‐transmission and self‐reception systems. The majority of recent studies in the field of IDAC for IRTHD pulse radars have focused on utilising time‐division approaches to avoid conflicts, thereby also creating competition for radar time resources. In this paper, a pointer scheduling algorithm based on Tabu search (PS‐TS) is proposed for IRTHD pulse radars, which solves the challenge of simultaneous efficient detection and communication. Firstly, the study presents a model for radar device‐to‐device (D2D) opportunistic communication and proposes a framework for pulse interleaving based on pointer scheduling to realise IDAC. Secondly, the PS‐TS algorithm employs a Tabu search strategy to maintain high‐quality solutions to avoid local optima and introduces a tolerance factor to maximise the communication success rate (CSR) with the minimal time expenditure. Simulation results indicate that the PS‐TS algorithm outperforms the genetic algorithm and particle swarm optimisation in terms of robustness, CSR, and computational efficiency, providing real‐time scheduling for IDAC systems.
Efficacy and safety of H-APC in Barrett's esophagus: Italian prospective multicenter study
Authors: Massimi Davide , Maselli Roberta , Pecere Silvia , Spada Cristiano , Andrisani Gianluca , Di Matteo Francesco Maria , La Terra Antonella , Coppola Franco , Capogreco Antonio , De Sire Roberto , Alfarone Ludovico , Menini Maddalena , Spadaccini Marco , Hassan Cesare , Repici Alessandro
Published: February 2025

Hybrid argon plasma coagulation (H-APC) is a novel technique for ablation of neoplastic Barrett's esophagus (BE), consisting in submucosal fluid injection and subsequent APC of visible BE. The aim of this study was to assess H-APC efficacy, safety, and tolerability.

We prospectively included patients undergoing H-APC ablation at four Italian Hospitals from September 2022 to March 2024. Patients with BE C3M5 maximum extent, low- or high-grade dysplasia (LGD, HGD) or residual BE after endoscopic resection (ER) of visible lesions were included. Patients who had undergone previous ablative treatments were excluded. The primary endpoints were complete eradication of intestinal metaplasia (CE-IM) and dysplasia (CE-D). Secondary endpoints were safety in terms of major and minor adverse events (AEs) and tolerability, assessed using pain (0–10) and dysphagia (0–5) scores within 7 days post-ablation (NCT05645679).

Among the 51 enrolled patients (mean circumferential 0.43 cm; standard deviation [SD] 0.72, mean maximum longitudinal 2.20 cm; SD 1.09) who completed treatment (80 H-APC sessions), 45.1% (23/51) had prior ER of visible lesions. All patients achieved both CE-IM and CE-D (51/51), requiring a mean of 1.51 sessions (SD 0.83). Only one case of fever and absolute dysphagia was observed (1/51; 1.96% AEs). Regarding tolerability, mean pain score was 1.3 (SD 1.99) whereas mean dysphagia score was 1.28 (SD 0.56).

The H-APC technique showed promising results in terms of effectiveness and safety with good tolerability in achieving initial CE-IM and CE-D in a selected population of BE patients.
Liver Transplant Anatomy: Basics for Interventional Radiologists
Authors: Patel Indravadan J. , Crawford Daniel A. , Naidu Sailendra G. , Wallace Alex , Knuttinen Grace , Oklu Rahmi , Alzubaidi Sadeer , Ozen Merve
Published: February 2025

Liver transplantation is becoming increasingly common in the United States, with very favorable 1- and 5-year survival rates. With increasing long-term survival rates, postprocedural vascular complications can occur with increased frequency. Familiarity with posttransplant vascular anatomy is essential for interventional radiologists dealing with this patient population. This article discusses the posttransplant venous, arterial, and biliary anatomy and the implications for minimally invasive interventions.
1.5 Radical Trifluoromethylation
Authors: Chen P. , Liu G.
Published: February 2025

The development of methods for the introduction of a trifluoromethyl group into organic molecules has been quite prominent over the last three decades. Among these methods, radical trifluoromethylation has gained renewed interest, and exhibits mild conditions together with good substrate compatibility and selectivity with the involvement of photo-, electro-, and metal-catalysis. In this review, a summary of these efforts is presented in two types of reaction pathways. The first is the addition of a trifluoromethyl radical to unsaturated moieties such as alkenes, alkynes, and (het)arenes. The second is the trifluoromethylation of ordinary carbon-centered radicals, including alkyl, alkenyl, and aryl radicals.
First-sound propagation in nondegenerate 3He–4He solutions
Authors: Adamenko I. N. , Nemchenko K. É. , Tsyganok V. I.
Published: February 2025

The problem of the velocity and absorption of first sound in superfluid solutions 3He–4He is solved for arbitrary frequencies over the entire temperature range where the quasiparticle description is applicable. The computational results are compared with existing experimental data.
Comparison of the acoustic properties of CuO and YBa2Cu3Ox ceramics in the temperature range 5–310 K
Authors: Pal’-Val’ L. N. , Pal’-Val’ P. P. , Natsik V. D. , Dotsenko V. I.
Published: February 2025

Absorption and velocity of ultrasound were compared in samples of the ceramics CuO and YBa2Cu3Ox (x = 6.95 and 6.3) in the temperature range 5–310 K and frequency range 47–370 kHz. The temperature spectra of the ultrasonic absorption in CuO and YBa2Cu3Ox ceramics in the intervals 30–60 and 235–250 K are qualitatively similar; they contain peaks P1 and P4, whose behavior as a function of the frequency of the oscillations is the same for both compounds. The largest differences in the ultrasonic absorption spectra in CuO and YBa2Cu3Ox are observed in the temperature range 100–200 K. The peaks P2 and P3, which are characteristic for the ceramic YBa2Cu3Ox, are not present in the spectrum of CuO ceramic. The temperature dependences of the sound velocity in the ceramic CuO were investigated for the first time and hysteresis under thermal cycling, similar to the hysteresis observed previously in YBa2Cu3Ox, was observed. The existence of hysteresis in CuO as well as in the tetragonal samples of YBa2Cu3Ox is inconsistent with the supposed twinning nature of this material. Evidently, a phase transition occurs and the hysteresis is caused by the development of domain strucutre in the low-temperature phase.
Radiation of an extrinsic crystal under conditions of a order–disorder phase transition
Authors: Gorobchenko V. S. , Eremenko V. V. , Ogurtsova L. A. , Pyshkin O. S.
Published: February 2025

The fine-structure stimulated-emission spectra of a paraterphenyl crystal with naphthalene impurity was investigated in the temperature interval 5−10 K. Anomalous behavior of the stimulated-emission lines was observed in the temperature range 15−25 K and is tentatively attributed to the presence of a phase transition, close to a phase transition of the order–disorder type, in the matrix at a temperature of ≃19 K.
Transport critical currents in ultrafine-grained high-temperature superconductors
Authors: Krasil’nikov A. S. , Mamsurova L. G. , Trusevich N. G. , Shlyakhtina A. V. , Shcherbakova L. G.
Published: February 2025

Information about the magnitudes and the field and temperature dependences of the transport critical currents in YBa2Cu3O7–δ ceramic high-Tc superconductors with various dispersities (the grain sizes are varied from ∼ 1 μm to ∼ 10 μm) is obtained from an analysis of the magnetization curves. Measurements show that the critical currents attainable in fine-grained superconductors produced by preliminary mechanical activation are an order of magnitude higher than in samples prepared by conventional ceramic technology.
Point-contact study of the heavy fermion system URu2Si2
Authors: Nowack A. , Naidyuk Yu. G. , Chubov P. N. , Yanson I. K. , Menovsky A.
Published: February 2025

We have performed a series of point-contact experiments, i.e., measurements of the voltage-dependent resistance, on single crystals of the heavy-fermion metal URu2Si2, which is both antiferromagnetic and superconducting, in the temperature range between 0.8 and 20 K. Our most important results are strong anomalies due to antiferromagnetism below TN = 17 K. These anomalies seem to be composed of parts, one fitting into the self-heating picture while another is possibly spectroscopic. It is unique that neither the thermal nor the ballistic models seem to be adequate for description of these point contacts. In the characteristics of high-ohmic contacts we find a zero-bias maximum of a width comparable to that of a charge- or spin-density wave gap found by specific heat measurements. For the superconducting state below Tc = 1.3 K, our measurements indicate a zone of strongly suppressed superconductivity near the surface.
I–V characteristics of point contacts on untwinned high-T
c material YBa2Cu4O8
Authors: Steiner P. , Karpinski J. , Wachter P.
Published: February 2025

We have measured the first and the second derivative of the I–V characteristics of point contacts on the high-Tc superconductor YBa2Cu4O8 (Tc = 79 K) by pressing together two pieces of bulk material. One side of the contact was a ceramic piece or an untwinned single crystal of YBa2Cu4O8. At the other side, a variety of material were used, such as etched wires of tungsten, molybdenum and copper, or single crystals of the investigated material as well. We observed interesting structures at 75 meV. They may also may be related to phonon structures which we observed in reflection measurements.
Investigation of single particle tunneling in BiPbSrCaCuO (2:2:1:2 and 2:2:2:3 phases)
Authors: Leonyuk L. I. , Pedyash M. V. , Petrov D. K. , Sethupathi K.
Published: February 2025

The results obtained from tunneling measurements by break junction method on monocrystalline and polycrystalline samples BiPbSrCaCuO in the temperature range 4.2 K ≤ T ≤ Tc are discussed. The I–V and dI/DV(V) characteristics shows a well pronounced gap structure. The gap parameter Δ was determined by the distance between the dynamic conduction peaks with high accuracy in a wide temperature range up to Tc. The dependence of gap parameters plotted versus critical temperatures Tc for BiPbSrCaCuO is a straight line and agrees well with other authors results for different high-Tc superconductors (2Δ/kTc = 6.2±0.6). The temperature dependence of gap parameter is in good agreement with formal BCS theory.
Interaction of electrodes in YBa2Cu3O7–x/metal tunnel junctions
Authors: Plecenik A. , Grajcar M. , Darula M. , Beňačka Š.
Published: February 2025

Different values of energy gap (10–30 meV) of high-Tc superconductors were observed by tunneling spectroscopy. The tunneling structures were realized by direct connection of YBa2Cu3O7–x and normal metal (Pb, Sn, In, Au). X-ray photoemission spectroscopy analyses and time dependence of tunneling resistance confirm a strong interaction between electrodes and the existence of oxygen depleted layer in YBa2Cu3O7–x near the tunneling barrier. The differences in the values of energy gap we explain by the existence of this oxygen depleted layer. The differential characteristics dV/dI (V) of YBa2Cu3O7–x/metal junctions were compared with the theoretical curves obtained from conventional theory for S-I-N connection. The time evolution of tunneling resistance of our junctions was fitted by theoretical curves describing the diffusion of oxygen through the interface of the junction.
Fluctuations in the magnetoresistance of a ballistic metallic point contact
Authors: Kokkedee J. A. , Holweg P. A. M. , Caro J. , Verbruggen A. H. , Jansen A. G. M. , Radelaar S. , Wyder P.
Published: February 2025

We have observed fluctuations in the magnetoresistance of a lithographically fabricated ballistic metallic Ag point contact. The effect is studied as a function of applied voltage across the constriction, which directly determines the excess energy of the electrons. A small applied voltage across the constriction changes the observed magnetofingerprint asymmetrically under bias reversal keeping the rms amplitude roughly constant. At higher voltage (V ≥ 10 mV), coinciding with the first phonon peak in the spectrum, a strong decrease in fluctuation amplitude is observed. We explain our results in terms of quantum interference of electrons, the length scale of the trajectories of interfering waves being the elastic mean free path.
Analysis of cryogenic problems in production of lunar helium-3
Authors: Zhitomirskii I. S. , Mikheev V. A. , Rudavskii É. Ya.
Published: February 2025

We analyze the technological process, developed for lunar conditions, for the purification and extraction in pure form of the light helium isotope contained in the gas mixture produced by heating lunar dust. The problem is connected with the development and implementation of the new and promising field of thermonuclear fusion1). A technology scheme is suggested which comprises an eight-stage refrigeration-and-purification assembly and a helium isotope rectification unit. Necessary energy consumption is estimated.
Peculiarities of the magnetization of magnetic materials with single-ion anisotropy in arbitrary oriented magnetic field
Authors: Zavadskii É. A. , Zavorotnev Yu. D.
Published: February 2025

We consider behavior of low-temperature ferro- and antiferromagnets of the easy-plane type with spin s = 1 in a magnetic field oriented at a small angle to the crystal’s principal axis. Behavior of ferromagnets is shown to depend on field orientation. In the case of antiferromagnet, magnetization anomalies can arise at comparatively large angles due to the finite magnitude of the spin moment.
Effect of Peierls relief on the low-temperature plasticity of pure CdTe crystals
Authors: Lirtsman V. G. , Lubenets S. V. , Natsik V. D. , Fomenko L. S.
Published: February 2025

The stress relaxation kinetics is investigated in the vicinity of the yield stress in pure CdTe crystals in the temperature range 200–300 K. The thermoactivation analysis of the results is carried out by assuming that: (1) the motion of dislocations under plastic deformations is hampered by thermally unsurmountable barriers forming effective internal stresses, as well as by Peierls barriers which can be overcome due to a thermally activated formation on the dislocation line and due to a dispersion of kink pairs along this line; (2) the limit of small effective stresses (as compared with Peierls stresses) is realized in the experiment. A satisfactory agreement is obtained between the experimental results and the model. The empirical values of the kink pair energy, Peierls stress, the linear density of the intrinsic energy of a dislocation, internal stresses, and the separation between supersteps on screw dislocations playing the role of athermal barriers are obtained.
Structure phase transition of the Peierls type in two-dimensional systems in a magnetic field
Authors: Gvozdikov V. M.
Published: February 2025

It is shown that a two-dimensional metal (or semiconductor), placed in a quantizing magnetic field perpendicular to its plane and experiencing the field of a one-dimensional periodic potential within the metal plane, is unstable against the appearance of a series of Peierls-type phase transitions periodic in the inverse field 1/H. The critical temperature as a function of the magnetic field H has the form of Tc(H) pulses (restricted to a finite range of fields) whose span is much narrower than the period of the sequence. The periodicity in 1/H is controlled by two factors: by the de Haas–van Alphen oscillation period as well as by the period of oscillations of the Landau bandwidth at the Fermi level, which is a function of the ratio of the cyclotron radius to the period of the one-dimensional potential.
Proton dynamics and anomalies of the low-temperature (1.5–130 K) pyroelectricity of KH2PO4 single crystals
Authors: Esengaliev A. B. , Novik V. K. , Novikov V. N. , Gavrilova N. D. , Zaitseva N. P. , Lotonov A. M. , Bogatyreva S. V.
Published: February 2025

To explain the observed abnormal behavior of the pyroelectric coefficient of KH2PO4 at low temperatures (T < 20 K) we suggest a two-component model in which in the field of the main component PSm(T) of matrix spontaneous polarization whose temperature variation is controlled by the vibration anharmonism of the perfect crystal lattice an additional component PSd(T) is formed due to the dynamics of the intrinsic structure elements of KH2PO4, viz. protons. The presumed mechanism of formation of PSd (T) and the pyroelectric coefficient γdσ is a “polar phase-polar phase” phase transition in the proton subsystem at T = 21–23 K. It has been established that the form of γmσ(T) depends on the history (regimes of growth and pretreatment) of samples and defect concentration.
Exactly solvable models of an effectively two-dimensional Luttinger liquid
Authors: Zvyagin A. A.
Published: February 2025

Effectively two-dimensional, exactly solvable quantum models of the Luttinger liquid type are suggested. The ground state energy is found, and the behavior of the considered systems in external electromagnetic fields is analyzed. In particular, an anyon behavior is predicted for charge and spin excitations under the conditions of the Aharonov–Bohm experiment, similar to the quantum Hall effect.
Total absorption of infrared radiation in thin metal black-body layers
Authors: Blank A. Ya. , Kasumov F. K. , Sharshanov A. Ya. , Shilyaev A. A.
Published: February 2025

Possibility of total absorption of the radiation from the IR range is shown for thin (less than the wave length) layers of small metal particles. The absorption has a monotonic character within a wavelength band ∼ 1-10 μm. The absorption mechanism due to excitation of surface modes in quasi-one-dimensional grains aggregated of small metal particles is indicated and the electromagnetic wave absorption length is calculated for the highly dispersed medium under consideration.
Phase separation kinetics in superfluid 3He–4He solutions
Authors: Mikheev V. A. , Rudavskii É. Ya. , Chagovets V. K. , Sheshin G. A.
Published: February 2025

Using simultaneous measurements of first-sound velocities and dielectric permeabilities we carried out an investigation of the phase separation kinetics in superfluid 3He–4He mixtures at temperatures below 150 mK. Processing of the obtained results within the framework of the recently developed theory allowed us to elucidate growth dynamics of nuclei of the new phase from the metastable supersaturated mixture.
Vibro-rotation effect in liquid 4He
Authors: Kolesnik V. I. , Sokolov S. S. , Mikheev V. A.
Published: February 2025

Conditions of existence of the vibro-rotation effect in liquid 4He have been studied as a function of the frequency and the velocity amplitude of the rotation-exciting vibrations as well as of the liquid helium temperature. It is shown that within the range from 80 Hz to 1 kHz, at those frequency values, where the vibro-rotation effect occurs, the temperature and amplitude dependences of the angular velocity of rotating liquid helium can be described within the framework of the available theory. The experimental deviations from the predictions of the theory that have been found are explained as being caused by effects of the geometry and the mechanical properties of the real device on the effect observed. The effect is established to be sensitive to the harmonic number of the exciting vibrations.
On the frequency shift of a magnetic resonance line during its narrowing
Authors: Sabirov R. Kh.
Published: February 2025

The shift in the magnetic resonance line relative to the Larmor frequency is estimated at low temperatures under conditions when the first moment of the magnetic resonance line is equal to zero. The case of a spherical sample with a cubic lattice is studied for both concentrated and dilute paramagnets.
Optical manifestation of excitons in semiconductors with an extrinsic surface potential
Authors: Halevi P. , Pérez-Rodríguez F.
Published: February 2025

We have studied theoretically the influence of the surface-potential shape on the exciton reflectivity for semiconductors with treated surfaces. In this investigation a continuous model for the surface potential has been employed, namely a generalized Morse potential which has been truncated at the surface. Our exact analytic calculation is reviewed, and the results are applied to CdSe for normally incident and for p-polarized light. Special attention is paid to the optical effects related to the localization of near-surface excitons. We find that the manifestation of excitonic bound states, originated by the surface-potential well, in the reflectivity spectra depends strongly on the type of polarization of the incident wave. For p-polarized light, due to its polaritonic nature a localized exciton can give rise to two reflectivity resonances at different frequencies. One of these has essentially the character of a transverse mode, while the other is basically longitudinal. Our interpretation relies on a comparison of the excitonic polarization vector and the wave function of the mechanical exciton.
On the inverse population in the nonequilibrium state of superconductors under optical pumping
Authors: Gulyan A. M.
Published: February 2025

Theoretical investigations show that states with inverse population can exist in superconductors with a non-Debye type of phonon spectrum and a very large value of the Cooper gap.
Superconducting state of GdBa2Cu3O6+δ single crystal (δ = 0.56; 0.75)
Authors: Levchenko G. G. , Pashchenko A. V. , D’yakonov V. P. , Markovich V. I. , Fita I. M. , Pavlyuk A. V. , Kozeeva L. P.
Published: February 2025

The temperature dependence of the critical current density is determined from an analysis of the temperature dependences χ′(T) and χ″(T) the real and imaginary components of magnetic susceptibility of GdBa2Cu3O6+δ single crystals by using Bean’s model of the critical state. The superconducting state of this material was found to be very complex due to the qualitative composition of the samples and the possibility of dimensional crossover of the superconducting properties.
Magnetoelastic waves in orthoferrites with non-Kramers rare-earthions
Authors: Buchel’nikov V. D. , Bychkov I. V. , Shavrov V. G.
Published: February 2025

The influence of the rare-earth subsystem on the spectrum of magnetoelastic waves in orthoferrites with non-Kramers rare-earth ions is investigated theoretically and found to be of fundamental importance. The expressions for the activation of spin waves and the velocity of quasielastic waves in the region of spontaneous spin-orientation phase transitions are derived. The obtained theoretical results are compared with the available experimental data on magnetoelastic waves in TmFeO3 and HoFeO3.
Saturation effect under longitudinal pumping in a biaxial two-sublattice spin chain
Authors: Zvyagin A. A. , Segal Ya. Yu. , Tsukernik V. M.
Published: February 2025

The resonance effect produced by a varying magnetic field parallel to the constant field on a two-sublattice spin chain with biaxial magnetic anisotropy is studied theoretically. It is shown that the system does not exhibit a parametric instability. The absorbed power is determined and the resonance frequency-field dependences are investigated.
Effect of argon impurity on the molar volume of solid CO2
Authors: Strzhemechnyi M. A. , Kovalenko S. I. , Solodovnik A. A.
Published: February 2025

The molar volumes Vm of CO2–Ar solid solutions with an argon concentration c varying between 0 and 100% are measured by using the transmission electron diffraction technique. On the CO2 side, the Vm vs c dependence has a peculiar form of a curve with a peak. A semiquantitative theory proposed for explaining this which takes into account not only the spherical component of interaction between particles in the solution, but also the presence of anisotropic forces in solutions rich in the molecular component.
Davydov splitting of vibrational spectrum by the two-dimensional dipole system
Authors: Rozenbaum V. M.
Published: February 2025

Davydov splitting of the vibrational spectrum of a two-dimensional rectangular lattice of dipoles in an electric field perpendicular to the lattice plane is calculated. The magnetic field dependence of the temperature of transition to a phase with orientationally ordered projections of the dipole moments on the lattice plane is estimated. The proposed theory explains the observed properties of the system of CO molecules absorbed on the NaCl (100) surface, in which the transverse field is due to adsorption potentials.
Peculiarities of ibuprofen interaction with polyethylene glycol polymer matrix
Authors: Doroshenko I. , Rudenok T. , Lesiuk A. , Smal A. , Dmytrenko O. , Davtian L. , Drozdova A.
Published: February 2025

The peculiarities of the interaction of ibuprofen with polyethylene glycol (PEG 400) have been studied by FTIR spectroscopy and computer simulation. Quantum chemical calculations of the optimal geometry and IR spectra of two conformers of the ibuprofen molecule were performed at the MP2/6-311 + G (2d,p) level of theory. The calculation results were compared with the experimentally recorded spectra of pure ibuprofen. FTIR spectra of pure ibuprofen and PEG 400 and their solutions at different concentrations (4% and 30%) were registered and analyzed. Molecular docking simulation of non-covalent interactions between ibuprofen and PEG molecules was performed using AutoDock4.2.6 software. It was established that PEG 400 can act as an effective inert matrix for the transfer of ibuprofen without changing its functional properties.
Investigation of multilayer samples of porous silicon with periodic structure by spectroscopic ellipsometry
Authors: Veremeichyk T. V. , Makarenko O. V. , Shevchenko V. B. , Ivanchuk S. Y. , Rybalochka A. V.
Published: February 2025

In this article, multilayer samples of porous silicon (PS) with a periodic structure, fabricated by electrochemical etching, are studied before and after air annealing. The experimental dependences of the parameters ψ, Δ, and the p-component intensity of the reflected light component at different angles of incidence on the wavelength before and after annealing were obtained by spectroscopic ellipsometry. The samples differ in the thickness of the periodic layers and their porosity. Using the Complete EASE software, theoretical models were created that well describe the experimental dependencies. The total thickness and optical characteristics of the samples before and after annealing were determined using the theoretical models. It was found that after annealing, the structure, chemical composition, and refractive index n of both samples of pitted silicon change. It has been shown that as a result of the applied heat treatment, the refractive index of all layers in multilayer samples decreases, which is associated with the oxidation of PS. Although after annealing the fraction of silicon and porosity in all layers decreases, their complete oxidation does not occur. All layers remain porous and contain silicon and silicon oxide. The overall thickness of the multilayer PS increases slightly after annealing.
Features of stimulated Raman scattering of a mixture of laser dyes in random media and possibility of using them in Raman spectroscopy
Authors: Yashchuk Vasil P. , Komyshan O. O. , Zelensky S. E. , Tikhonov E. A.
Published: February 2025

Stimulated Raman scattering (SRS) of pyrromethene 597 (PM597) and rhodamine 6G (R6G) mixture in vesicular polymeric films is investigated depending on the dye concentration ratio. SRS in this mixture occurs together with the random lasing (RL) of both dyes, which stimulates it. When the RL spectrum of one dye (Pm 597) is broader than the other (R6G), its RL emission stimulates the SRS of that other dye beyond its own RL spectrum. Such a situation was demonstrated at the dominant concentration of PM597 in a mixture with R6G, at which its RL spectrum becomes broader than that of R6G. Due to this, the RL radiation of PM597 is able to stimulate the SRS of R6G without participation of the own latter’s RL radiation. This can be used for determine the Raman spectrum of the latter in more widely spectral range. It is shown that this approach is promising for expanding the possibilities of Raman spectroscopy of laser dyes.
Inflation process of radially closed parachute
Authors: Guan Le , Yu Gang , He Xia , Li Run
Published: February 2025

Parachute closing technology can effectively control the parachute deployment process and overload and is an important technology to ensure the safe opening and normal use of the parachute. Radially closed parachutes are more effective in achieving faster and more consistent canopy inflation than traditional circumferential closing parachute technology. This study is based on numerical simulation technology and explores the working mechanism of the intake control system through comparison of experimental data. The ALE method (arbitrary Euler–Lagrangian penalty function method and multi-medium arbitrary Lagrangian–Euler algorithm) is used to construct the incompressible flow field and the coupled dynamic model of the radially closed and circumferentially closed parachute structures. Combined with the inflated shape of the airdrop test, the simulation results of the two types of closed parachutes are compared and analyzed. The study found that the radially closed parachute forms a high-pressure area through the inner parachute and a low-speed vortex area inside the canopy, which increases the pressure difference between the inside and outside of the canopy, makes the inflation more full, the stress distribution more uniform, and the parachute opening overload and speed better. It is suitable for the delivery and recovery of heavy-duty materials at low altitude and lays the foundation for further improved design and engineering application of the air intake control system.
Evolution of methane adsorption characteristics in coal under N-Methylpyrrolidone treatment
Authors: Wang Zheng , Li He , Shi Shiliang , Lu Yi , Ye Qing
Published: February 2025

The extraction of coalbed methane (CBM) from low-permeability coal beds is a key matter for coal mine safety. The microporous system of coal has a significant influence on its gas adsorption capacity. To reveal the evolution of the microporous system and methane adsorption characteristics of coal under solvent treatment, CO2 and methane isothermal adsorption experiments were carried out. The experimental results show that the N-Methylpyrrolidone (NMP) solvent significantly modifies the micropore structure of coal. After NMP treatment, the maximum reductions in the pore volumes of lignite, bituminous coal, and anthracite are 64.99%, 24.05%, and 11.29%, respectively. Their adsorption constant a values decrease by 55.13%, 27.48%, and 9.32%, respectively. and b values decrease by 52.14%, 21.47%, and 16.25%, respectively. The swelling of macromolecular polymers is the main contributor to the reduction in micropore volume. NMP has a significant impact on lignite and bituminous coal, while its effect on anthracite is slightly weaker. This indicates that NMP can help to solve the challenges of coalbed methane extraction.
Fixational eye movements as active sensation for high visual acuity
Authors: Nghiem Trang-Anh E. , Witten Jenny L. , Dufour Oscar , Harmening Wolf M. , Azeredo da Silveira Rava
Published: February 2025

Perception and action are inherently entangled: our world view is shaped by how we explore our environment through complex and variable self-motion. Even when fixating stable stimuli, our eyes undergo small, involuntary movements. Fixational eye movements (FEM) render a stable world jittery on our retinae, which can be expected to harm neural coding. Yet, empirical evidence suggests that FEM help rather than harm human perception of fine detail. Here, we elucidate this paradox by uncovering under which conditions FEM improve or impair retinal coding and human acuity. We combine theory and experiment: model accuracy is directly compared to that of healthy human subjects in a visual acuity task. Acuity is modeled by applying an ideal Bayesian classifier to simulations of retinal spiking activity in the presence of FEM. In addition, empirical FEM are monitored using high-resolution eye-tracking by an adaptive optics scanning laser ophthalmoscope. FEM introduce variability in retinal ganglion cell activity, but they also effectively preprocess inputs to facilitate retinal information encoding. Based on an interplay of these mechanisms, our model predicts a relation between visual acuity, FEM amplitude, and single-trial stimulus size that quantitatively accounts for experimental observations and captures the beneficial effect of FEM. Moreover, we observe that while human subjects’ FEM statistics vary with stimulus size, our model suggests that subjects’ FEM amplitude remains within a near-optimal range, where acuity is enhanced compared to much larger or smaller amplitudes. Overall, our findings indicate that perception benefits from action even at the fine spatiotemporal scale of FEM.
Final report, onoing key comparison BIPM.QM-K1, ozone at ambient level, comparison with UBA, July 2023
Authors: Viallon Joële , Idrees Faraz , Moussay Philippe , Wielgosz Robert , Travnicek Wilma , Meyer Caroline , Norris Jim , Trask Peter
Published: February 2025

Main text

As part of the ongoing key comparison BIPM.QM-K1, a comparison has been performed between the ozone standard of Germany maintained by the Umweltbundesamt (UBA) and the common reference standard of the key comparison, maintained by the Bureau International des Poids et Mesures (BIPM). The instruments have been compared over a nominal ozone amount fraction range of 0 nmol mol-1 to 500 nmol mol-1.

To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database https://www.bipm.org/kcdb/.

The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).
Origin of the recirculation flow pattern induced by nanosecond discharges and criterion for its development
Authors: Roger Edouard , Mariotto Pierre , Laux Christophe O
Published: February 2025

Non-equilibrium plasmas generated by spark discharges induce chemical, thermal, and flow dynamic effects that are beneficial in many applications such as plasmalysis, plasma-assisted combustion, and plasma flow control. Among the flow dynamic effects generated by these discharges, vorticity is of particular interest because it enhances the mixing of the discharge products with the surrounding environment and accelerates the cooling of the kernel. This article provides a comprehensive examination of the vorticity produced by nanosecond discharges in air. Using computational fluid dynamic simulations of the blast wave resulting from energy deposition in the interelectrode volume during the nanosecond pulse, we analyze the various sources of vorticity during the post-discharge period. The non-uniform strength of the leading shock of the blast wave is found to be the primary promoter of vorticity. Other sources, such as the barocline torque, play a secondary role in explaining the overall recirculation pattern. In addition, the discharge cooling mechanisms are also investigated. The cooling regimes and their efficiencies are classified according to the discharge parameters, such as the inter-electrode gap, the initial kernel temperature, or the frequency of repetitive pulses. Finally, a physics-based, non-dimensional number Π*, equal to the ratio of the initial kernel temperature to the ambient temperature, is introduced. A numerical analysis shows that the transition between the recirculating and non-recirculating flow regimes occurs for Π* on the order of 10. This criterion is validated against experimental and numerical results from the literature.
Effect of AlN coating on the electromagnetic properties of FeSiAl soft magnetic composites
Authors: Guo Rongdi , Qin Jiaxiang , Wu Guohua , Hu Zhongqiang , Liu Ming
Published: February 2025

Soft magnetic composites (SMCs) are considered key elements for attaining electromagnetic signal transmission and conversion. However, they require high permeability and low core losses to ensure the efficient and stable operation of electronic devices, such as inductors and sensors. To effectively address these issues, in this work, AlN nanopowders were used to coat FeSiAl spherical particles. In parallel, the effect of coating AlN nanopowders on the electromagnetic properties of FeSiAl SMCs was investigated. By performing energy dispersive spectroscopy analysis, AlN was confirmed to be attached to the FeSiAl spherical particles, indicating the existence of an excellent AlN coating quality. Although the incorporation of the AlN coating layer yielded a monotonic reduction in saturation magnetization intensity and effective permeability, it also effectively suppressed core losses. Due to the high-resistance of AlN, the high-resistance layer developed on the surface of the FeSiAl particles can substantially increase the resistivity of FeSiAl SMCs, and then the eddy current loss was suppressed. When coated with 1.5 wt% AlN, the FeSiAl SMCs exhibited the lowest core losses of 394 kW m−3 at 100 kHz, 100 mT, and room temperature. The proposed AlN-coated FeSiAl SMCs in this work exhibited a good overall performance, and are expected to be applied in high-performance inductor devices.
Experimentally-informed numerical investigation of a high-power magnetically shielded Hall thruster operating on xenon and krypton
Authors: Perales-Díaz J , Domínguez-Vázquez A , Ahedo E , Di Sarli A , Kitaeva A
Published: February 2025

The operation of a 20 kW magnetically shielded Hall effect thruster, with xenon and krypton as propellants, is numerically studied with a 2D (axial-radial) axisymmetric hybrid (particle-in-cell/fluid) code. Thrust efficiency with Kr is 2% to 6% lower than with Xe. Kr exhibits smaller propellant utilization, voltage utilization and divergence efficiencies. Contrary to what is observed in previous works, the current efficiency is higher with Kr. Apart from the dissimilar mass and electronic properties of Xe and Kr atoms, the widening of the ionization and acceleration zones with Kr, with respect to the Xe discharge, plays an important role in the Xe–Kr differences in performance. The level of plume velocity dispersion with both propellants is found similar due to two opposing effects: on the one hand, the stronger overlap of the ionization and acceleration zones with Kr leads to a larger dispersion on a per species basis; and, on the other hand, the smaller fraction of doubly-charged ions with Kr reduces the overall dispersion efficiency. Magnetic shielding is effective with both Xe and Kr as propellants, with slightly higher ion impact energy on the walls in the Kr discharge.