bluuebunny/crossref_metadata_2025 huggingface dataset:
Radio emission from little red dots may reveal their true nature
Authors: Latif Muhammad A. , Aftab Ammara , Whalen Daniel J. , Mezcua Mar
Published: February 2025

Context. The unprecedented sensitivity of the James Webb Space Telescope (JWST) has revolutionized our understanding of the early Universe. Among the most intriguing JWST discoveries are red, very compact objects that show broad line emission features, nicknamed little red dots (LRDs). The discovery of LRDs has triggered great interest in their origin as either extremely starbursting galaxies or highly obscured active galactic nuclei (AGNs). Their exact nature remains unknown.

Aims. The goal of this work is to estimate the radio emission from LRDs and predict which radio surveys would detect them. To achieve these objectives, we employed the fundamental plane of black hole (BH) accretion to estimate radio emission from AGNs and the stellar radio fluxes from their host galaxies. We assumed a range of BH masses, X-ray luminosities (LX), and star formation rates (SFRs) to bracket the likely properties of LRDs.

Methods. Our findings suggest that BH radio fluxes from LRDs are 10–100 times higher than the stellar fluxes from their host galaxies, depending on the BH mass, LX, and SFR. The detection of a ∼500 nJy signal above 2 GHz at z ≥ 5 or a ∼2000 nJy flux at z = 3–4 would be a smoking gun for the presence of AGNs provided that SFRs in the host galaxies are < 30 M⊙ yr−1.

Results. We find that LRDs are most likely radio-quiet AGNs; otherwise, they would have already been detected in the current radio surveys. Our findings suggest that LRDs can be detected with upcoming radio observatories such as ngVLA and SKA with integration times of 10–100 h, respectively.
Molecular pathogenesis of Cryptosporidium and advancements in therapeutic interventions
Authors: Lu Yilong , Zhang Xiaoning , Guan Zhiyu , Ji Rui , Peng Fujun , Zhao Chunzhen , Gao Wei , Gao Feng
Published: February 2025

Cryptosporidiosis, caused by a Cryptosporidium infection, is a serious gastrointestinal disease commonly leading to diarrhea in humans. This disease poses a particular threat to infants, young children, and those with weakened immune systems. The treatment of cryptosporidiosis is challenging due to the current lack of an effective treatment or vaccine. Ongoing research is focused on understanding the molecular pathogenesis of Cryptosporidium and developing pharmacological treatments. In this review, we examine the signaling pathways activated by Cryptosporidium infection within the host and their role in protecting host epithelial cells. Additionally, we also review the research progress of chemotherapeutic targets against cryptosporidia-specific enzymes and anti-Cryptosporidium drugs (including Chinese and Western medicinal drugs), aiming at the development of more effective treatments for cryptosporidiosis.
Das oregis-Dashboard: webbasiertes Benchmarking in der augenheilkundlichen Versorgungsforschung in Deutschland
Authors: Zimmermann Julian Alexander , Dicke Christopher , Arndt Maren , Hollosi Noel-Adrian , Storp Jens Julian , Eter Nicole
Published: February 2025

Einleitung Oregis, das digitale Register der Deutschen Ophthalmologischen Gesellschaft (DOG), dient als zentrale Plattform zur Erfassung und Analyse von Versorgungsdaten in der Augenheilkunde in Deutschland. Ziel von oregis ist es, ein umfassendes Bild der aktuellen Versorgungslage zu schaffen und die Versorgungsforschung durch Real-World-Daten aus ambulanten und stationären Einrichtungen zu fördern. Seit seiner Einführung im Jahr 2020 verzeichnet oregis eine kontinuierliche Ausweitung der Datenbasis, die wissenschaftliche Analysen zu vielfältigen Fragestellungen ermöglicht. In dieser Arbeit wird die neue Dashboard-Funktion vorgestellt, die teilnehmenden Zentren den Vergleich eigener Patientendaten mit den Gesamtdaten in Echtzeit erlaubt, sowie datenschutzrechtliche Aspekte beleuchtet.

Material und Methoden In Anlehnung an bestehende medizinische Register beschloss der oregis-Lenkungsausschuss die Einführung des oregis-Dashboards. Zunächst wurden 49 nationale und internationale Register analysiert, um gemeinsame Merkmale wie die Möglichkeit des Benchmarkings zu identifizieren. Im Anschluss erfolgten technische Umsetzung und Implementierung.

Ergebnisse Jedes an oregis angebundene Zentrum hat über einen sicheren Zugang Zugriff auf das oregis-Dashboard, das die wichtigsten Indikatoren zu Patienten, Diagnosen und Behandlungen abbildet. Dynamische Filteroptionen ermöglichen eine gezielte Datenanalyse, wobei die Ergebnisse des eigenen Zentrums anonymisiert mit aggregierten Daten anderer Zentren verglichen werden. Die technische Basis für das Dashboard bildet Apache Superset. Die Datenübertragung erfolgt über den oregis-Konnektor, der patientenbezogene Daten nach festgelegten Standards anonymisiert. Umfangreiche Sicherheits- und Datenschutzmaßnahmen gewährleisten die Datensicherheit, einschl. serverseitiger Verschlüsselung, Transportverschlüsselung und 2-Faktor-Authentifizierung. Das Dashboard ist Bestandteil eines umfassenden Datenschutzkonzepts, das von Datenschutzexperten für oregis entwickelt und validiert wurde.

Schlussfolgerung Die Zahl der an oregis angeschlossenen Zentren wächst kontinuierlich. Das neue, webbasierte Dashboard ermöglicht es, Daten flexibel zu analysieren und mit anderen Zentren zu vergleichen, ohne Rückschlüsse auf einzelne Versorgungseinheiten zuzulassen, wodurch der Datenschutz und die Unabhängigkeit der Zentren gewahrt werden. Mit dem Wachstum von oregis können weitere Funktionen ergänzt werden, um einen besseren Überblick über die augenheilkundliche Versorgung in Deutschland zu schaffen.
Venookklusive erektile Dysfunktion: aktuelle Übersicht und klinischer Leitfaden
Authors: Galimov Rustam
Published: February 2025

Erektile Dysfunktion (ED) ist einer der häufigsten Vorstellungsgründe in der urologischen Praxis. Trotz des wesentlichen Fortschritts im Verständnis der Pathophysiologie der ED bleiben noch einige vaskuläre Ursachen, wo diagnostische und therapeutische Maßnahmen nicht einheitlich sind.

Was ist der richtige Weg bei Verdacht auf eine venöse Leckage? Was ist der Stellenwert der venösen ligierenden Operationen und der radiologischen Interventionen?

Die narrative Literaturübersicht der vorhandenen Quellen hinsichtlich der venösen kavernösen Insuffizienz.

Die Ursachen der kavernösen venösen Insuffizienz sind heterogen. Die effektivste Behandlunsgmethode ist Implantation einer Schwellkörperprothese. Die venösen ligierenden Operationen oder radiologischen Interventionen sind keine verlässliche Therapieoption aufgrund des Rezidivrisikos.

Die Patienten mit einer kavernösen venösen Insuffizienz sind Kandidaten für die Implantation einer Schwellkörperprothese. Die Gefäßinterventionen bei dieser Patientengruppe können im Rahmen von klinischen Studien durchgeführt werden.
Sleep and respiratory infections
Authors: Boira Ignacio , Chiner Eusebi
Published: February 2025

Sleep disorders that involve circadian rhythm disruption and sleep-disordered breathing (SDB) such as obstructive sleep apnea (OSA) are closely linked to respiratory infections. SDB leads to a proinflammatory state due to intermittent hypoxia, sleep fragmentation, increased oxidative stress, and elevation of inflammatory mediators such as tumor necrosis factor (TNF), interleukin-6 (IL-6), and C-reactive protein (CRP). Furthermore, inflammatory mediator levels correlate with SDB severity, especially in people with OSA. Nocturnal microaspiration, gastroesophageal reflux, and associated comorbidities (e.g. obesity) increase the risk of community-acquired pneumonia, viral infections such as SARS-CoV-2, respiratory complications, and death. OSA has been associated with post-COVID syndrome. It also increases the risk of postoperative complications in both adults and children. Circadian rhythm disorders such as insomnia predispose to immune disorders and increase the risk of infection.
Chronic conditions such as bronchiectasis, with or without concomitant cystic fibrosis, can lead to structural sleep changes and increase the risk of OSA due to chronic cough, arousals, aspirations, hypoxia, upper airway edema, and overexpression of proinflammatory cytokines. The protective effect of treatment for sleep disorders against respiratory infection is currently unknown. However, in people presenting with respiratory infection, it is important to test for SDB to prevent complications.
Inflammatory and Bleeding Risks on Clinical Outcomes in Acute Coronary Syndrome Patients Undergoing Percutaneous Coronary Intervention
Authors: Duan Yixuan , Qiu Miaohan , Na Kun , Liu Daoshen , Zhou Shangxun , Xu Ying , Qi Zizhao , Liu Haiwei , Xu Kai , Wang Xiaozeng , Li Jing , Li Yi , Han Yaling
Published: February 2025

Objective This study aimed to evaluate the impact of systemic inflammation burden using high-sensitivity C-reactive protein (hsCRP) and long-term prognosis in acute coronary syndrome (ACS) patients undergoing percutaneous coronary intervention (PCI) stratified by bleeding risk status.
Methods Consecutive patients admitted for ACS and who received PCI between March 2016 and March 2022 were enrolled in the analysis. Elevated systemic inflammation was defined as hsCRP>2 mg/L, and high bleeding risk (HBR) was defined the Academic Research Consortium (ARC)-HBR criteria. The primary outcome was ischemic events at 12 months, composed of cardiac death, myocardial infarction, and/or stroke. The main secondary outcomes included all-cause death, and Bleeding Academic Research Consortium (BARC) types 2, 3, and 5 bleeding and types 3, and 5 bleeding.
Results Of 15,013 patients, 4606 (30.7%) were qualified as HBR and 8395 (55.9%) had hsCRP>2 mg/L. Elevated hsCRP were consistently associated with higher risk of ischemic events in both HBR (adjusted hazard ratio [aHR]: 1.20; 95% confidence interval [CI]: 0.91-1.58) and non-HBR (aHR: 1.34; 95% CI: 1.01-1.78) subgroups (P interaction=0.755). Although the bleeding events incidence was higher in HBR patients, an elevated hsCRP level was not associated with bleeding events regardless of HBR status. Restricted cubic spline regression represented an inverse J-shaped relation between hsCRP and non-HBR for ischemic events (P nonlinearity <0.001) and all-cause death (P nonlinearity = 0.003).
Conclusion Regardless of HBR status, high levels of hsCRP were associated with an increased risk of ischemic events and all-cause death in ACS patients following PCI, but not for bleeding.
Advances in the 1,2-Metalate Rearrangement Chemistry of Alkenylboronates
Authors: Tran Minh-Khoa , Ready Joseph M.
Published: February 2025

Synthetic methods that involve the formation of multiple bonds in a one-pot fashion have played a crucial role in organic chemistry. However, many features of these approaches are still limited, such as stereocontrol and chemoselectivity, especially when non-adjacent stereocenters are formed. Herein, we outlined our efforts in addressing these challenges by advancing the 1,2-metalate shift of alkenylboronic esters.
Round Ligament of the Uterus: Radiological and Surgical Perspective
Authors: Patil Aruna Raman , Ramamurthy Harshita
Published: February 2025

The round ligaments of the uterus are a pair of fibromuscular cord-like structures derived from the gubernaculum and serve as a secondary support system for the uterus. The round ligaments have varied clinical and surgical implications. The involvement of round ligaments by pathological processes is underestimated. Advancements in imaging, visualization, and evaluation of round ligaments have widened our understanding of various developmental anomalies and diseases, resulting in better prognostication and management.
Magnetic orientation phase transition in Gd2CuO4: resonance, magnetic, and acoustical investigations
Authors: Zvyagin A. I. , Yablonskiĭ D. A. , Pashchenko V. A. , Kobets M. I. , Stepanov A. A. , Shcherbina M. V. , Zherlitsyn S. V. , Zvyagina G. A. , Fil’ V. D. , Barilo S. N. , Zhigunov D. I.
Published: February 2025

Magnetic, antiferromagnetic-resonance, and ultrasonic investigations of the spin-orientation phase transition induced by an external magnetic field in Gd2CuO4 at low temperatures are reported. A theory of the static and resonance properties of Gd2CuO4 is formulated on the basis of a symmetry analysis, taking into account the real multiple-sublattice structure of the compound and interaction between the copper and rare-earth subsystems. The magnetic structure of Gd2CuO4 is determined by comparing the theory with experiment.
Josephson current between partially dielectricized superconductors with spin-density waves
Authors: Voitenko A. I. , Gabovich A. M. , Shpigel’ A. S.
Published: February 2025

The temperature dependences of the critical current Ic, flowing through a symmetric Josephson junction between antiferromagnetic superconductors whose electronics spectrum is partially dielectricized, are calculated. The temperature dependences of the superconducting gap Δ and the critical current Ic exhibit small differences from the classical Muhlschlegel and Ambegoakar–Baratoff curves. The critical current Ic drops sharply with increasing dielectric gap Σ and with decreasing parameter v = Nnd(0)/Nd(0), where Nnd and Nd are the electron density of states on the nondielectricized and dielectricized sections of the Fermi surface, respectively. It is proposed that Cr1−xRex, and URu2Si2 samples can be used to check the theory experimentally.
Role of the anisotropy of the electron energy spectrum in electromagnetic generation of sound in tungsten
Authors: Irklienko T. M. , Korolyuk A. P. , Fal’ko V. L. , Khizhnyi V. I.
Published: February 2025

The electromagnetic generation of longitudinal sound in tungsten in a magnetic field oriented perpendicular to the surface of the sample was investigated experimentally and theoretically. It is shown that this effect is caused by the anisotropy of the Fermi surface and the deformation potential of the carriers belonging to the hole ellipsoids N. The experiment was performed on tungsten single crystals at temperature T ≲ 4.2 K at frequencies ω/2π = 80−150 MHz. The theory agrees qualitatively with experiment.
Thermal expansion of solid hydrogens
Authors: Soldatov A. V. , Aleksandrovskiĭ A. N. , Manzheliĭ V. G. , Raleĭ V. V. , Strzhemechnyĭ M. A.
Published: February 2025

The linear thermal expansion coefficient α of solid deuterium with paramodification content of 2.25% was determined in the temperature interval 1.5–5.6 K. The contributions of the translational vibrations of the lattice αlat and the rotational motion of the molecules αrot to α are separated. The temperature dependence of αlat was determined by the expression αlat = 1.475 · 10−7T3 + (4.5–7)·1010T5. The possibilities of a universal description of the thermal expansion of cryocrystals with a central interaction, including quantum crystals of hydrogen isotopes, are discussed. A theoretical description is proposed and the temperature dependence of αrot is analyzed.
Temperature dependence of the resistivity of systems with heavy fermions
Authors: Zagoskin A. M. , Rozhavskii A. S. , Tuluzov I. G.
Published: February 2025

We propose on the basis of a two-band model of heavy-fermion systems a nonmagnetic mechanism for the nonlinear temperature dependence of the resistivity. The mechanism is based on the competition between the temperature–induced increase in the intensity of electron-phonon scattering and the decrease in the effective carrier mass on the Fermi surface as a result of the strong temperature dependence of the chemical potential. The qualitative form of the basic types of experimental curves ρ(T) as a function of the parameters of the system (width of the narrow band, interband hybridization potential, position of the Fermi level, and intensity of electron-phonon and electron-impurity interactions) is reporduced correctly.
Temperature dependence of the linear magnetoelectric effect in orthorhombic boracites
Authors: Chupis I. E.
Published: February 2025

An explanation is proposed for the difference in the temperature dependences of the magnetoelectric susceptibility components α23 and α32 of rhombic boracites in the vicinity of the transition temperature to the weakly ferromagnetic state. The problem is analyzed on the basis of Landau’s theory for multiple-sublattice magnets, and it is shown that the observed peak for the component α32 in orthorhombic boracites is attributable to the contribution of antiferromagnetism vectors.
Superconductivity of the HTS compounds Y1–xCaxBa2Cu4O8 ∓y
Authors: Makarov V. I. , Kleiner V. Z. , Ovcharenko O. N. , Tereshina N. S. , Blinkin A. A. , Golovin V. N. , Derevyanko V. V. , Finkel’ V. A. , Shakhov Yu. N.
Published: February 2025

Crystal lattice parameters of 1–2–4 compounds are measured as functions of calcium concentration in the interval 0<x <0.3. The degree of rhombic distortion of the crystal lattice is found to be nonlinear. The effect of hydrostatic pressure on the superconducting transition temperature of 1–2–4 compounds with a substitution of yttrium by calcium is studied. The dependence of Tc and the pressure derivative of Tc on calcium concentration (0<x <0.3) is found to be nonlinear. Possible mechanisms of the observed nonlinear dependences of Tc and dTc/dP on x are discussed.
Magnetoresistance of an electron crystal over liquid helium
Authors: Grigor’ev V. N. , Dotsenko V. V. , Kirichek O. I. , Kovdrya Yu. Z. , Pogorelov L. A. , Sivokon’ V. E. , Sobolev V. I.
Published: February 2025

The longitudinal magnetoresistivity δxx of an electron crystal over liquid helium is measured at temperatures below 0.3 K for surface electron concentrations ns = (4–10)× 108 cm−2 in magnetic fields H up to 1.5 kOe. Low temperatures were attained by using a dilution refrigerator with 3He condensation pumping ensuring a continuous cryogenic circulation cycle. A distinguishing feature of the refrigerator is its vibration-free operation, which is essential for experiments with objects like surface electrons. It is that in the temperature region under investigation the value of ρxx is inversely proportional to ns, is practically independent of temperature, and increases with H anomalously strongly. It is also found that crystallization affects weakly the magnetic field dependence of ρxx. A considerable discrepancy between theoretical and experimental results is observed.
Point-contact spectroscopy of the intermetallic compounds
Authors: Reiffers Marian
Published: February 2025

The point-contact spectroscopy experimental results on the intermetallic compounds are reviewed. The measurements of point-contact spectra in the spectroscopic (ballistic) regime enable the determination of electron-quasiparticle interaction (EQI) functions. The phonon part of the EQI is usually common for the isostructural classes of compounds. The influence of magnetic field on the point-contact spectra permits investigation of various effects (e.g., the Zeeman effect). The results on valence-fluctuation and heavy-fermion compounds are explained by two approaches.
Cyclotron spectroscopy of electron–phonon relaxation in point contacts
Authors: Andrievskii V. V. , Ass E. I. , Komnik Yu. F.
Published: February 2025

Injection of charge carriers into a metal through a point contact promotes high nonequilibrium in the electron–phonon system. Some of the injected electrons go back to the point contact as a result of interaction with intrinsic excitations in the metal and define the nonlinear properties of the contact. These processes provide the basis of the point-contact spectroscopy of electron–phonon interaction1. A considerable part of the injected electrons penetrates deep into the metal, bringing away the information on the relaxation processes in the point contact. Thus, the current-carrying point contact may be used as a source of nonequilibrium electrons whose distribution in energy bears information on electron–phonon relaxation in the metal. The distribution can be investigated by the method of electron focusing by transverse magnetic field2 which is based on cyclotron motion of the charge carriers. The geometry of the experiment is shown in Fig. 1 (see the insert). Two contacts are placed on the same surface of a metallic crystal separated by a distance which is smaller than the electron mean free path. One of the contacts is the source of nonequilibrium electrons and the other is a probe, the latter being used to measure the potential at the metal surface induced by focusing electrons.
Calculation of point-contact spectra for a simple heavy-fermion Hamiltonian by two approaches. Comparison of results
Authors: Kupka M. , Farkašovsky P.
Published: February 2025

Point-contact spectra have been calculated for a normal metal–heavy-fermion metal system (described by means of a simplified model Hamiltonian). Two approaches are used: one of them states that the differential conductance reflects an energy-dependent quasi-particle density of states, and the second one derives the differential conductance from the energy-dependent electronic transmission coefficient through the interface. Results of these two approaches are compared.
Calculation of point-contact spectra of metals with an energy-dependent density of states
Authors: Nowack A. , Klug J.
Published: February 2025

The influence of an energy-dependent electronic density of states (DOS) on the point-contact characteristics is studied within the fremework of the standard ballistic point-contact theory. We calculate dV/dI vs. V characteristics numerically for the case of an electronic DOS with a maximum near the Fermi-energy, as it is assumed to exist in heavy-fermion systems. Our calculations yield features as maxima and an asymmetry with respect to zero bias, which are indeed typical for heavy-fermion systems. In the case of dominating elastic scattering, as it is present in alloys, we find that dV/dI characteristics show an approximate image of the electronic DOS, i.e., a “negative” of the DOS image of a dV/dI tunneling characteristic.
Kondo-like anomalies in point-contact characteristics of ferromagnetic EuFe2P2
Authors: Klug J. , Nowack A. , Jeitschko W.
Published: February 2025

We have investigated the dV/dI vs V characteristics of point contacts between ferromagnetic EuFe2P2 (Tc = 27 K) and a normal metal (Cu, Au) as function of temperature (4 K < T < 80 K). In the magnetically ordered state a pronounced zero-bias maximum is observed, which appears to be split in some cases. This is unusual for point-contact measurements on magnetic materials performed up to now, but is strongly reminiscent of the anomalies found in the characteristics of Kondo and spin-glass systems. The splitting of the zero-bias maximum indicates a local (internal) magnetic field in the contact region. An external magnetic field causes a linear increase of the width of the splitting which may be described by an effective g-value of ≈35.
Linear conductance backgrounds in tunnel junctions
Authors: Kirtley J. R. , Washburn S. , Scalapino D. J.
Published: February 2025

Linear conduction backgrounds, which have been emphasized recently in connection with tunneling measurements of the high-Tc superconductors, are actually quite general. We argue that they may be due to inelastic tunneling from a broad distribution of states. This view is supported by: 1) the temperature dependence of this background; 2) quantitative analysis of Pb phonon features using the inelastic hypothesis; and 3) measurements of Al–AlOx–Pb junctions with CrOx included in the barrier region, which show that the background arises from interactions in the tunneling barrier. Suppression of the Al gap signature, and magnetic field dependent modifications of the conductance background, indicate a spin-dependent interaction mechanism in Al–CrOx–Pb junctions. The observation of the linear background out to very large voltages may be indicative of multiple scattering in the tunneling process. Monte Carlo calculations of strong multiple scattering inelastic tunneling are presented to explore this possibility.
Self-consistent resistance calculations for point contacts
Authors: van Gelder A. P.
Published: February 2025

A method is proposed for solving the semi-classical transport problem for a point contact. It accounts for multiple (in)elastic scattering events in a numerically efficient, systematic way.
Determination of the element composition of the impurity–helium solid phase
Authors: Boltnev R. F. , Gordon E. B. , Krushinskaya I. N. , Pel’menev A. A. , Popov E. A. , Pugachev O. F. , Khmelenko V. V.
Published: February 2025

A solid phase consisting of van der Waals helium “coats” that are frozen together surrounding impurity atoms of heavier rare gas elements has been proven to exist. For “dry” (i.e., taken out of liquid helium) samples, we have found the stoichiometric ratios S = NHe/Nim for Ne, Ar, N, and N2 impurity centers. These results confirm the fact that the solid phase under study consists mainly of helium and the measured ratios S = 12–17 for nitrogen and neon are close to those expected for a close-packed monolayer helium coat. Results are obtained which give evidence that a liquid phase of van der Waals helium spheres is possible to exist at a temperature close to the critical sample destruction temperature (Td ≃ 8 K).
Magnetic properties of the Hubbard model with an infinite repulsion on a rectangular anisotropic lattice
Authors: Ezerskaya E. V. , Cheranovskii V. O.
Published: February 2025

Hubbard’s model with an infinite repulsion on a rectangular anisotropic lattice with Ln-center segments is analyzed. For lattices with L + 1 electrons and cyclic boundary conditions, an exact dependence is obtained between the lattice dimensions and critical values of the Hubbard Hamiltonian parameters at which the ferromagnetic order is violated.
Thermal conductivity of the HTS system YBa2Cu3–xAgxO7–δ
Authors: Anders É. E. , Derevyanko V. V. , Kudryavtsev I. N. , Nemchenko K. É. , Startsev S. V. , Finkel’ V. A.
Published: February 2025

Thermal conductivity κ(T) of the HTS ceramic YBa2Cu3–x AgxO7–δ (x = 0, 0.15, 0.30) is measured in the temperature interval 4.2–150 K. A comparative analysis of the peculiarities of the temperature dependence κ(T) is carried out for different concentrations of silver. Dominating mechanisms of heat transport are identified and the corresponding physical parameters are determined for the system YBa2Cu3–x Agx O7–δ.
Point-contact spectroscopy of a marginal Fermi liquid
Authors: Beloborod’ko S. I. , Omel’yanchuk A. N. , Tuluzov I. G.
Published: February 2025

The point-contact spectroscopy of a marginal Fermi liquid is studied. The temperature and field dependences of the point-contact current and differential resistance are found. The obtained point-contact spectrum makes it possible to reconstruct the spectral function gm (ω) in metal oxides.
On the theory of quantum magnetoconductivity of surface electrons in helium at low temperatures
Authors: Monarkha Yu. P.
Published: February 2025

The dependence of the quantum transport of surface electrons on the form of the density of states for Landau levels and correlation effects is studied in a two-dimensional electron gas in helium at low temperatures.
Linear magnetic splitting of optical absorption bands in an easy-plane antiferromagnet
Authors: Eremenko V. V. , Shapiro V. V. , Kachur I. S. , Piryatinskaya V. G.
Published: February 2025

A study of the optical absorption spectrum of the easy-plane two-sublattice antiferromagnetic MnCO3 in an external magnetic field reveals a linear splitting of bands having the same origin as the linear magneto-optical effect. The splitting is of intraionic type and is induced by the spin-orbit interaction in second-order perturbation theory.
Theory of the antiferromagnetic semimetal state induced by a strong magnetic field in bounded superconducting salts from the family(TMTSF)2X
Authors: Petrova T. G. , Rozhavskii A. S.
Published: February 2025

A semiclassical theory is constri1cted for a spin-density wave induced by a strong magnetic field in a quasitwo-dimensional metal with an open Fermi surface modeling the electron spectrum of layered bounded superconducting salts in the family (TMTSF)2X (Betchgaard salts). It is shown that a cascade of first-order phase transitions occurs above the threshold field Hc. The dependence Tc(H) is calculated, and the quantum Hall effect in the spin-density wave phase is explained by assuming the chemical potential pinning in the localized states gap.
FIR absorption in O2–N2 solid solutions
Authors: Pritula I. M. , Khashchina L. V.
Published: February 2025

Far infrared (FIR) absorption spectra of the (O2)1–x(N2)x binary system (x = 0, 0.01;...; 1.0) were measured in the spectral range 20 to 100 cm−1 and in the temperature range from 8 to 47 K. We traced an effect of the nitrogen impurity on the intensity, position, and halfwidth of the magnon and lattice modes of solid oxygen. It has been established that the weakening of the integrated absorption band intensities with increasing nitrogen concentration in the mixture is likely to occur in virtue of the simple depletion of the amount of α-O2 in the sample (the effect similar to the sample thinning in pure oxygen).
Quasiparticle states induced by superconducting current in S–I superlattices
Authors: Kuplevakhskii S. V. , Fal’ko I. I.
Published: February 2025

It is shown that, in the presence of a supercurrent, the energy spectrum of an S–I superlattice (where S stands for a superconductor and I for an insulator) contains a Bloch band of quasiparticle states with energies lying in the region of the gap. The width of the Bloch band is a rapidly oscillating function of the superlattice period.
Linear magnetoelectric effect in a two-layer ferroelectric–ferromagnetic system
Authors: Chupis I. E.
Published: February 2025

Surface linear magnetoelectic effect (LMEE) is studied in semi-infinite ferroelectric-ferromagnet and semi-infinite ferroelectric-ferromagnetic film contact systems. It is shown that the value of LMEE increases on the contact surface in direct proportion to the dielectric susceptibility of the ferroelectric.
Glass-like behavior of the Kr–14N2 solid solution at comparatively low nitrogen fractions. Calorimetric studies
Authors: Bagatskii M. I. , Manzhelii V. G. , Muromtsev P. I. , Minchina I. Ya. , Ivanov M. A.
Published: February 2025

The heat capacity of Kr–14N2 solid solution is investigated in the 0.5 to 12 K temperature range and with nitrogen fractions, n, from 4% to 29%. Analysis of results with the use of previously published data for lower nitrogen fractions has shown that the heat capacity of the rotational sybsystem, ΔC, reveals a behavior in the concentration region n⩾0.7% that is typical of glasses. Hence, the heat capacity ΔC is a linear function of temperature, and the temperature range where the relationship ΔC ∝ T holds becomes wider with increasing nitrogen fraction. In addition, the value of ΔC in this region depends weakly on the nitrogen fraction. A theoretical description is suggested which agrees qualitatively with experimental results.
Anisotropy of thermopower and electric conductivity in single-crystal EuBa2Cu3O at hydrostatic pressures up to 12 kbar
Authors: Kraidenov V. F. , Itskevich E. S.
Published: February 2025

Within the temperature range from 4.2 to 300 K we studied temperature dependence of the thermopower α and the electric resistivity ρ of a EuBa2Cu3O6.3±0.1 single crystal under hydrostatic pressures up to 12 kbar. It is found that both αab and αc for all T and P are positive and tend to saturate at T = 300 K. Within the 100–300 K range, ρab and ρc run in a semiconductor-like manner decreasing with pressure, while αab and αc grow with an average rate of d ln α/dP = 1.5 ⋅ 10−5 bar−1. This is opposite in sign as to the behavior of α under pressure in theYBa2Cu3Ox (x = 6.4–6.9) ceramic investigated by us earlier.
The influence of crystal structure inhomogeneities on electrical resistance and thermoelectric power of Cu3Au alloys
Authors: Kourov N. I.
Published: February 2025

The electric resistance and the thermoelectric power of Cu3Au alloys with different extents of atomic ordering are measured in the temperature range 4.2–350 K. It is found that the violation of the Matthiessen rule observed in these alloys and the behavior of the low-temperature thermoelectric power are due to anisotropic effects and a change in the electron spectrum associated with the appearance of superbands upon ordering.
Cyclotron resonance in potassium in a normal magnetic field
Authors: Zimbovskaya N. A.
Published: February 2025

The influence of zero-curvature points of the Fermi surface at cyclotron orbits of effective electrons on the impedance of a metal with a nearly spherical Fermi surface in a normal magnetic field is considered under conditions of the anomalous skin effect. It is shown that the cyclotron resonance observed in potassium in a normal magnetic field can be described theoretically by taking into account these peculiarities of the Fermi surface.
Low-temperature plastic deformation of tin single crystals with cadmium impurity
Authors: Kirichenko G. I. , Natsik V. D. , Soldatov V. P.
Published: February 2025

Work-hardening curves are obtained for Sn–Cd alloys with Cd concentrations 0.01, 0.21, and 0.53 at.% in the temperature interval 4.2–100 K. The impurity is found to have a noticeable temperature-dependent effect on the work-hardening curves. The temperature dependences of the yield stress and the duration of the easy slip stage are also determined.
Soft mode in two-phonon Raman scattering spectra for quasi-one-dimensional conductors
Authors: Dolgov E. N. , Sherman E. Ya.
Published: February 2025

A new method is proposed for the optical observation of a soft phonon mode, which is based on an analysis of Raman spectra in quasi-one-dimensional metals.
Development of a high-stability FHD (total-field F, horizontal component H, and declination D) geomagnetic vector magnetometer based on bias and compensation fields
Authors: Ju Haihua , Xia Zhong , Ge Jian , Zhang Cen , Zhang Le , Li Bin , Dai Jia
Published: February 2025

Geomagnetic vector measurement can obtain more geomagnetic information, which is one of the main development directions of geomagnetic measurement. To date, the magnetic flux gate magnetometer is the main tool for geomagnetic vector measurement; however, its drift issue cannot be ignored. To address this issue, we propose a geomagnetic vector measurement method based on bias and compensation fields and then develop a high-stability FHD (total-field F, horizontal component H, and declination D) vector magnetometer based on a proton sensor and a magnetic field generator. In addition, a dedicated experimental platform is constructed to verify the performance of the developed magnetometer in a geomagnetic station. Compared to the flux gate magnetometer, the experimental results indicate that the fourth-order differential noise of the declination D, horizontal component H, and vertical component Z are 1″, 0.27, and 0.15 nT, respectively, which are all lower than those of the flux gate magnetometer. In addition, the horizontal component H and vertical component Z of the flux gate magnetometer indicate more than 30 and 60 nT startup drift, respectively; in contrast, the proposed FHD magnetometer shows an excellent stability during a 16 h observation time.
High resolution multicolor holograms encoded into color print images with hybrid dielectric/plasmonic metasurfaces
Authors: Mousavi Khaleghi Seyed Saleh , Wen Dandan , Cadusch Jasper , Crozier Kenneth B.
Published: February 2025

Multicolor holograms encoded into color print images are structures that generate holographic images when illuminated with lasers, while showing completely different images when viewed with the eye or with microscopes under white light incoherent illumination. Despite their promising applications in optical document security, they have been the subject of only a handful of research efforts, underscoring the need for further exploration in this area. Here, we propose a hybrid metasurface that achieves this functionality and thoroughly characterize its performance using simulations. In our device, nanohole arrays in an aluminum film function as plasmonic color filters for blue, green, and red channels with low crosstalk. Amorphous titanium dioxide (aTiO2) nanopillars comprise the hologram metasurface, which modulates the outgoing light's phase to produce a holographic image. Due to the subwavelength dimensions of the unit cell of the color filter (e.g., 415 nm for red, 315 nm for green, and 255 nm for blue wavelengths) and metasurface hologram (e.g., 430 nm for red, 360 nm for green, and 305 nm for blue wavelengths), the color print and holographic images can have very high resolution. Simulations reveal that the metasurface can be perceived as a tricolor image under incoherent white light, whereas under illumination from red, green, and blue lasers, three distinct holographic images can be observed.
Laboratory results from an ultra-stable MID IR spectrometer for exo-planet atmosphere characterization
Authors: Fixsen D. J. , Staguhn J. G. , Sharp E. , Maher S. , Mandell A. M. , Brown A.
Published: February 2025

We have conducted a set of experiments on a TES (Transition-Edge Superconductor) bolometer detector array, demonstrating that a flux measurement stability better than 5 parts per million (ppm) over periods of hours to days, can be achieved with modest thermal stability requirements. This level of measurement stability is critical in enabling measurements of the atmospheric signatures of terrestrial-sized exoplanets around nearby K and M stars, including those in the star’s habitable zone. The demonstration uses a simple tungsten filament light bulb as the source, a photo diode operating at 0.5 μm as a stability monitor for the light bulb, and a grating spectrometer in the 5–15 μm wavelength range.
Cavitation erosion risk on a hydrofoil using a multi-scale method
Authors: Yang Yingdi , Xiong Chengwang , Wang Shiping , Zhang A-Man
Published: February 2025

The present study employs a two-way coupled multi-scale method to simulate and analyze the cloud cavitation flow around a hydrofoil, based on which the distribution of cavitation erosion risk on the hydrofoil is evaluated. The numerical results demonstrate that the multi-scale method can capture not only the overall evolution characteristics of cloud cavitation but also the generation, growth, and collapse of small-scale bubbles. Throughout the majority of a cavitation cycle, the scale of the Lagrange bubbles roughly follows a logarithmic Gaussian distribution. However, it shows a double-peak characteristic as a result of bubble production from both the sheet cavity and the shedding cloud. The distribution of local erosion risk, which is closely aligned with experimental findings, is assessed based on the collapse of small-scale bubbles. The erosion risk is greatest near the closure line of the sheet cavity, which is due not only to the collapse of bubbles around the shedding cloud but also to the shedding and breakdown of small-scale vapor structures during the development of the reentrant jet. During the cavitation cycle, the erosion risk is highest when the shedding cloud forms and the erosion risk decreases as it moves downstream. The multi-scale numerical analysis reveals that the cavitation number alone is insufficient for characterizing cavitation and its erosive effects. For a given cavitation number, the mean diameter of Lagrange bubbles increases with the inflow velocity. Furthermore, the total impact energy from bubble collapse on a hydrofoil follows a power-law dependence on the inflow velocity.
Comparison of statistical behavior of wall-attached motions in rough and smooth open channel flows
Authors: Jing Siyu , Duan Yanchong , Zhu Dejun , Li Danxun , Cao Liekai
Published: February 2025

A set of high-resolution, time-resolved particle image velocimetry measurements were conducted in an open channel, with closely arranged glass spheres of 6 mm used to rough the bed, at low to moderate Reynolds numbers (Reτ≈ 600–2000) and intermediate to high relative submergences (h/ks = 6.3–14.7, where h is the flow depth and ks is the equivalent roughness height). Analyses of the wall-attached motions (WAMs) in rough-wall open channel flows (OCFs) are performed using linear coherence spectra at various wall-normal positions, and results of two smooth-wall OCFs are also included for comparison (Reτ≈ 500 and 900). The WAMs in rough-wall OCFs exhibit self-similar properties in the region of 0.2 <y/h< 0.8 (y is the wall-normal position and h is the flow depth), where the critical wavelength of WAMs (denoted as λxWA) increases linearly with y. Furthermore, WAMs in rough OCFs have larger streamwise wavelengths (λxWA≈ 25 y) and inclination angles (θuuWA≈ 18°) compared to their smooth-wall counterparts (λxWA≈ 18.3 y, θuuWA≈ 14°). The strength of WAMs in rough OCFs was lower than that in smooth OCFs, due to the effects of rough wall elements.
Structural characteristics of a supersonic turbulent boundary layer subject to convex–concave curvature coupling
Authors: Ding Hao , Tian Lifeng , Wang Ao , Huang Kaiyou , Fu Shuangxu
Published: February 2025

With an inflow Mach number of 3.0, the structural characteristics of a supersonic turbulent boundary layer subject to a convex–concave coupled curvature are experimentally investigated by Nano-tracer Planar Laser Scattering (NPLS) technology. The NPLS images reveal intricate flow features, including multi-scale vortices, near-wall streaks, and oblique shock waves. Wall pressure measurements indicate a feedback mechanism between the turbulent structures and wall pressure within the curvature coupling region, resulting in the upstream shift of the minimum pressure point into the convex wall. Additionally, the oblique shock generated by the concave curvature leads to an increased wall pressure in the downstream flat plate. By utilizing fractal dimension analysis and two-point spatial correlation analysis, the complexity and morphology of the turbulent vortices are quantitatively described. It is found that no significant changes in fractal dimension near the curvature coupling point due to the hysteresis effect. Furthermore, the coherent structures in the inner boundary layer shrink before and after the curvature coupling point, also attributed to hysteresis. The turbulence structures in the middle layer show lower sensitivity to the convex curvature, indicating distinct responses of turbulence structures at different normal positions to the wall's geometric features. Statistical analysis of the vortex structures, including maximum Feret diameter, aspect ratio, and inclination angles, further confirms the enhanced vortex breaking up caused by the concave wall and the increased size disparities of vortex structures due to curvature variations.
Gyrokinetic simulation of isotope effect on zonal flow response in tokamaks
Authors: Li Shengming , Yang Dingkun , Xiao Yong
Published: February 2025

The isotope effect on zonal flow is a critical issue for turbulent transport in burning plasmas. In this work, we conduct global simulations of the isotope effects of hydrogen isotopes (H, D, and T) on the zonal flow across arbitrary wavelengths using the Gyrokinetic Toroidal Code. Our results reveal that the residual zonal flow (RZF) level exhibits a significant isotope effect primarily at intermediate wavelengths (i.e., krρi∼1). The strength of this isotope effect and the wavelength at which it is strongest are mainly influenced by isotope mass Mi and safety factor q, with a lesser impact from the inverse aspect ratio ε. The isotope effect intensifies as the isotope mass increases from H to T or as the safety factor q increases. Simulations incorporating kinetic electrons show that the contribution of electron polarization to the RZF level is minimal compared to that of thermal ions at intermediate wavelengths, indicating that electron polarization has a negligible effect on the zonal flow isotope effect. Additionally, our simulation results for the isotope effect on RZF, as well as on geodesic acoustic mode frequency and damping rate, align with analytic theories. However, we suggest that earlier analytic theory may overestimate the isotope effect on RZF in this crucial intermediate wavelength range. Overall, our findings indicate that the isotope effect on zonal flow may contribute to isotope turbulent transport, particularly in trapped electron turbulence and turbulence in high-q region.
Effect of triangular-wing longitudinal vortex generator geometry on heat transfer and flow resistance in the impingement cooling
Authors: Luan Jiaming , Fu Hao , Zhang Limin , Luan Yigang
Published: February 2025

To enhance the impingement cooling performance of turbine blades, this study investigates the heat transfer mechanisms of triangular-wing longitudinal vortex generators (TLVGs) arranged on the target surface. TLVGs are evaluated under different heights (H), widths (W), and angles (α) within a Reynolds number range of 4000 to 10 000. The main conclusions are as follows: Increasing H leads to an increase in heat transfer on the target surface and flow resistance, with the optimal overall heat transfer performance observed at H = 0.5D, improving thermal performance factor (TPF) by 7.5%–9.0% compared to a smooth target surface. The effect of W on the heat transfer performance of the target surface is relatively small, and its increase slightly reduces flow resistance. For Reynolds numbers below 6000, the TLVG with W = 0.1D shows the best overall heat transfer performance; however, for Reynolds numbers above 6000, the TLVG with W = 0.4D exhibits the optimal performance. The TLVG at α  = 60° significantly reduces flow losses in the impingement chamber, improving TPF by 6.8%–8.2% compared to a smooth target surface. The TLVG at α  = 150° has the next highest TPF, improving by 5.3%–6.0%, but it enhances heat transfer capability more effectively than at α  = 60°.
Fluid–structure boundary-driven simultaneous standard-inverse Chladni patterns for selective particles manipulation
Authors: Hou Zewei , Pei Yongmao , Xu Duo , Yu Bo , Lin Yuyang
Published: February 2025

In fluid, particles patterning and selective manipulation are essential for material, biomedical, and robotic handling. The German physicist Chladni has investigated the particles manipulation on a flat vibrating plate. Generally, particles bounce with the vibrating plate, gradually accumulate to nodal lines or anti-nodes, forming either standard or inverse Chladni patterns. The Chladni patterns show great potential for particles assembly in different environments. The mechanisms for simultaneous manipulation by multiple kinds of forces are still unclear. Here, the Chladni plate with a vertical boundary is used for selective particles manipulation. The simultaneous standard-inverse Chladni patterns are realized on the vibrating plate by modulating the frequency. First, the particles patterning mechanisms on the Chladni plate with vertical boundary are investigated for the acoustic radiation force and the acoustic streaming. The simultaneous standard-inverse Chladni patterns are realized due to the driving of vertical boundary. Then, through switching the excitation frequencies, the tunable particles patterns are realized. Finally, the selective separation of particles with different sizes and densities is investigated using the standard-inverse Chladni patterns. This work investigates the particles manipulation mechanisms on vibrating plate by the fluid–structure boundary-driven acoustic field, thereby potentially providing a platform for selective patterning and separation of particles.