bluuebunny/crossref_metadata_2025 huggingface dataset:
Quantitative grading of insulation damage to distribution transformers caused by high‐altitude electromagnetic pulse based on partial discharge detection
Authors: Qin Feng , Li Simeng , Chen Wei , Yang Yuxiang , Nie Xin , Wu Wei
Published: December 2024

Distribution transformers may experience insulation breakdown or degradation when exposed to the influences of high‐altitude electromagnetic pulse (HEMP), thus posing significant threats and uncertainties to the safety and stable operations of power systems. Therefore, this study constructs a HEMP impact‐test platform for distribution transformers, evaluates and analyses the development patterns of partial discharge (PD) under the action of different amplitude conduction environments, decomposes and identifies the types of damage defects, proposes a quantitative classification method for the degree of HEMP damage to distribution transformers based on PD detection. And reveals the damage mechanism of distribution transformers exposed to HEMP at different damage levels. The results show that distribution transformers undergo insulation breakdown when subjected to the influences of HEMP and that performance degradation often occurs before breakdown. As the amplitude of the HEMP environment increases, the degree of transformer damage continues to deteriorate, and both the amount of PD and the repetition rate of discharges exhibit a step‐wise increase, with the increase in the repetition rate lagging behind that of the discharge amount. Based on the patterns of discharge quantity and repetition rate, transformer damage is categorised into three stages: undamaged, latent defect discharge, and severe defect discharge.
Stress analysis and structural optimisation of insulating rods under dynamic and static loads
Authors: Jin Haifeng , Jin Lijun
Published: December 2024

This study aims to provide a theoretical basis for the fatigue characteristics and structural optimisation of insulating rods to enhance their reliability and lifespan in practical applications. This paper uses COMSOL to complete the stress analysis of insulating rods under dynamic and static loads based on the finite element method. The correctness of the model is verified based on the elastic‐plastic theory. The simulation results show that under the same load, the stress concentration area is more affected by the dynamic load, and the stress concentration position is highly consistent with the fracture position of the rod in the experiment. It verifies the impact on the insulating rods at different speeds and static load stress. Simulation shows that, in cases where the allowable stress is exceeded, as the number of operations increases, the fatigue characteristics will greatly affect the service life of the insulation rod. Finally, the fatigue analysis and structural optimisation of the insulating rod were completed, providing important reference values for the long‐term stable operation of ultra‐high voltage circuit breakers.
A non‐rigid point cloud registration method based on scene flow estimation
Authors: Deng Xiaopeng , Yang Kai , Wang Yong , Li Jinlong , Xie Liming
Published: December 2024

Point cloud registration is an important aspect of computer vision, encompassing various applications. However, many existing algorithms neglect the registration of non‐rigid point cloud. Recent studies have focused on scene flow, which can achieve non‐rigid point cloud registration by estimating the scene flow of two point clouds. The presence of occlusion in a scene is primarily attributed to variations in viewpoint and access time, thereby posing a significant challenge in accurately predicting scene flow. In the endeavour to mitigate this issue, the focus is on the propagation of scene flow originating from non‐occluded points towards occlusion points while concurrently estimating the occlusion map. The proposed network, a non‐rigid point cloud registration method based on scene flow estimation, achieves exceptional performance for the EPE3D metric on the FlyingThings3D and KITTI scene flow datasets, and it demonstrates strong generalization on the railroad dataset.
A two‐layer control strategy for fuel‐efficient connected vehicles
Authors: Bentaleb Ahmed , Hajjaji Ahmed El , Karama Asma , Rabhi Abdelhamid , Benzaouia Abdellah
Published: December 2024

This paper proposes a two‐layer control strategy to enhance connected vehicles fuel efficiency. Compared with previous works, this study proposes an approach to optimize both the vehicle speed and gearbox position to achieve better fuel efficiency. The control task is given in two stages: the upper layer and the lower layer. Before trip departure, the upper layer concurrently optimizes the vehicle speed and gearbox position based on road map information, and engine and vehicle parameters for an entire route. Then, while driving, the lower layer is used to follow the pre‐computed optimal profiles. Model predictive control follows the optimal speed while ensuring an adaptive safe distance constraint with a preceding vehicle. For gear shifting, an online shift control assuring the tracking of the optimal gear position is developed based on look‐ahead road data and vehicle actions. The effectiveness of the proposed control strategy was evaluated with comprehensive simulations and comparison tests using Matlab and CarSim software. The mean online optimization calculation time is 0.065 s, indicating its real‐time capability. The proposed method can be used as a driving assist system or implemented as a speed and gear controller for self‐driving vehicles.
Recent Advancements and Applications of Nanosensors in Oral Health: Revolutionizing Diagnosis and Treatment
Authors: Dewan Meghna , Shrivastava Deepti , Srivastava Kumar Chandan , Goyal Lata , Zwiri Abdalwhab , Hussein Areen Fareed , Alam Mohammad Khursheed , Anil Sukumaran
Published: December 2024

Advances in the field of nanomaterials are laying the foundation for the fabrication of nanosensors that are sensitive, selective, specific, cost-effective, biocompatible, and versatile. Being highly sensitive and selective, nanosensors are crucial in detecting small quantities of analytes and early diagnosis of diseases. These devices, operating on the nanoscale, detect signals, such as physical, chemical, optical, electrochemical, or biological, and then transduce them into a readable form. They show great promise for real-time, point-of-care, and home-based applications in health care. With the integration of wireless technology, these nanosensors, specifically biosensors, can potentially revolutionize therapeutic techniques. These advancements particularly impact the oral cavity, the primary entry point for various bodily substances. Nanosensors can transform oral and dental health practices, enabling timely disease diagnosis and precise drug delivery. This review examines the recent advancements in nanobiosensors, exploring their applications in various oral health conditions while discussing their benefits and potential limitations.
Exploring the Changes in Mild Cognitive Impairment Blood-Based Biomarkers after Local Antibiotic Periodontal Treatment in Diabetic Patients: Secondary Analysis of Data from a Randomized Controlled Trial
Authors: Ramadhani Aulia , Tanaka Azusa , Minagawa Kumiko , Takehara Sachiko , Yamada Takaho , Sone Hirohito , Kaneko Noboru , Nohno Kaname , Ogawa Hiroshi
Published: December 2024

Objectives This article investigates the changes in blood-based biomarkers associated with mild cognitive impairment (MCI) risk in type 2 diabetic patients following local antibiotic periodontal treatment.

Materials and Methods A secondary analysis of data from a 24-week randomized controlled trial was conducted, involving 27 patients with type 2 diabetes mellitus and periodontitis. Participants received periodontal treatment biweekly from baseline until the 6th week of the study. Sixteen patients were assigned to an intervention group and received local antibiotic periodontal treatment (Periofol 2%). The outcomes were periodontal inflammation score, which was measured using periodontal inflamed surface area, the inflammation markers levels (tumor necrosis factor-α, C-reactive protein, and interleukin [IL]-6), and MCI risk score, which was assessed using protein plasma analysis through blood test. The evaluations were performed at baseline and week 24th in both groups. The changes in periodontal inflammation scores, inflammation parameters, and MCI risk in baseline and week 24th were analyzed.

Statistical Analysis The Wilcoxon signed-rank test was used for within-group analysis and the Mann–Whitney U test was utilized for between-group analysis.

Results Periodontal parameters were improved in both groups (p < 0.05). IL-6, complement C3, and alpha-2-antiplasmin levels were significantly decreased in the intervention group (p < 0.05). In between-group comparisons, there was a significant difference between the control and intervention groups in apolipoprotein A1, apolipoprotein C1, and alpha-1-B glycoprotein levels in week 24th (p < 0.05).

Conclusion Even though the periodontal status showed significant improvement after being given local antibiotic periodontal treatment, the changes in MCI risk proteins plasma remained unclear.
Accuracy, Reproducibility, and Gaps in Different Angulations of 3D-Printed versus Milled Hybrid Ceramic Crown
Authors: Khwanpuang Nadaprapai , Suphachartwong Chayaporn , Klaisiri Awiruth , Leelaponglit Seelassaya , Angkananuwat Chayanit , Krajangta Nantawan
Published: December 2024

Objectives This article compared the accuracy, reproducibility, and gap of crowns resulting from variations in print angulation of three-dimensional (3D)-printed VarseoSmile Crownplus (VS) and milled resin-ceramic hybrid materials (Cerasmart 270, CS, and Enamic, E).

Materials and Methods A total of 60 specimens, consisting of VS printed at four different angulations (30, 45, 60, and 90 degrees), along with CS and E were investigated. External and internal accuracy and reproducibility were measured with the 3D deviation analysis. External and internal gaps were measured with the silicone replica technique. The results were analyzed using Welch's one-way analysis of variance with Dunnett T3 post hoc comparison at p ≤ 0.05.

Results Across all groups, external and internal accuracy were 0.55 to 20.02 μm and external and internal reproducibility were 0.05 to 0.69 μm. Overall external accuracy was not significant (p = 0.063), whereas significance was noted in overall internal accuracy and reproducibility among groups (p < 0.001). External and internal gaps were 33.76 to 93.11 μm. Statistically significant differences were found in internal and external gaps among groups (p < 0.001), with milled crowns demonstrating larger internal and smaller external gaps than 3D-printed crowns. Within the 3D-printed group, statistically, 90-degree angles exhibited the smallest external and internal gaps.

Conclusion Both milled and 3D-printed methods achieved clinically acceptable accuracy, reproducibility, and gap dimensions, offering viable options for hybrid ceramic crown restoration. Among 3D-printed crowns, the 90-degree printing angle group exhibited satisfactory accuracy and reproducibility, alongside the best internal and external fit.
Outcomes and Surgical Approaches for Pineal Region Tumors in Adults: A Retrospective Study of a Single-Center Over 12 Years
Authors: Moldabekov Aidos , Maidan Aiman , Ryskeldiyev Nurzhan , Ashirov Nurali , Borykbaev Nurzhan , Akshulakov Serik
Published: December 2024

Background Pineal region tumors are considered rare, deeply located, and very difficult to resect. They can cause various symptoms by compressing and obstructing different structures. Contradictory data have been reported regarding various aspects of surgical outcomes in different patient positioning.

Objectives Therefore, this retrospective study aimed to describe the variety of pineal region tumors and patient positioning in pineal region surgeries and compare the neurological outcomes during different approaches.

Materials and Methods From January 1, 2010, to December 31, 2022, 61 patients with pineal area tumors were hospitalized at the National Center for Neurosurgery. Thirty-five patients' histology examinations were available. Twenty-nine patients had open surgical excision. Regarding approaches, supracerebellar infratentorial, posterior transfalcine interhemispheric, and occipital transtentorial approaches were employed.

Results Among 35 patients, 17 had hydrocephalus and required ventricular drainage to address third ventricle obstruction. Complete tumor resection was achieved in 55% of patients. The mortality rate was 13.7% in the open surgical group and 15.625% in the endoscopic third ventriculostomy (ETV) group.

Conclusion Proper patient positioning and selecting the optimal approach are crucial for a successful outcome.
A Comparative Outcome of Full Endoscopic Lumbar Discectomy for L4/5 Central–Paracentral Disc Herniation: Interlaminar versus Transforaminal Approach: A 2-Year Prospective Randomized Controlled Follow-Up Study
Authors: Pruttikul Pritsanai , Pluemvitayaporn Tinnakorn , Ananpipatkij Palapat , Dorji Kinzang , Kunakornsawat Sombat , Surapuchong Suttinont , Ratanakoosakul Warot , Tiracharnvut Kitjapat , Piyasakulkaew Chaiwat , Kittithamvongs Piyabuth
Published: December 2024

Background The interlaminar and transforaminal approaches are commonly employed in full endoscopic lumbar spine surgery. Both approaches are well-suited for addressing specific types of lumbar disc herniation, particularly at the L4/5 level.

Objective This article compares the clinical outcomes of full endoscopic discectomy for L4/5 central–paracentral disc herniation between the interlaminar and transforaminal approaches.

Materials and Methods Sixty patients were randomly assigned to either a full endoscopic interlaminar discectomy group or a full endoscopic transforaminal discectomy group, with 30 patients each. The procedures were performed by a single spine surgeon at our institution between 2017 and 2019. Over a 2-year follow-up period, various parameters, including operative time, postoperative hospitalization duration, Visual Analog Scale (VAS) scores for leg and back pain, Oswestry Disability Index (ODI), and modified MacNab criteria, were assessed and compared between the two groups. Additionally, the complication rates were documented.

Results The two full endoscopic approaches resulted in significant improvements in back–leg pain measured by the VAS and in the ODI scores postsurgery. A comparison between the two approaches revealed a significant difference in the ODI score at the 6-week postoperative mark (p = 0.02). However, other clinical outcome parameters did not show significant differences at the other follow-up time points. Postoperative dysesthesia was more prevalent in patients who underwent endoscopic transforaminal discectomy (p < 0.05). The operative time was notably longer for the interlaminar approach compared with the transforaminal approach (62.6 ± 18.0 vs. 37.0 ± 13.6). Postoperative hospitalization time did not exhibit significant differences between the two groups.

Conclusion Both the interlaminar and transforaminal approaches demonstrate similar clinical outcomes in treating central–paracentral L4/5 disc herniation. Each technique presents distinct advantages and disadvantages regarding operative time and postoperative dysesthesia. The full endoscopic interlaminar and transforaminal approaches have proven to be safe and effective methods for addressing L4/5 central–paracentral disc herniation.
Why issue green bonds? Examining their dual impact on environmental protection and economic benefits
Authors: Zhou Di , Kythreotis Alexios
Published: December 2024

This article explores two primary questions: first, whether the issuance of green bonds contributes to environmental protection, particularly regarding their performance after the adoption of net-zero emission policies; and second, whether issuers of green bonds can have economic benefits. Using the Difference-in-Differences (DID) model to analyze green and conventional bonds issued from 2013 to 2023, the study finds no significant correlation between green bond issuance and CO2 emissions following net-zero adoption. Nevertheless, our findings are important and deserve attention as they indicate that the carbon reduction policies have not exerted sufficient pressure on bond issuers to reduce emissions. At the same time, however, a closer examination of issuing entities reveals that those issuing only green bonds tend to have higher ESG ratings, lower CO2 emissions, and lower financing costs. This suggests that such issuers achieve substantial environmental benefits and economic advantages. In contrast, entities issuing both conventional and green bonds do not demonstrate the same environmental benefits. This finding raises concerns about potential greenwashing, suggesting that entities issuing both green and conventional bonds may engage in practices that contradict environmental protection while presenting their activities as environmentally friendly through green bonds. The study also highlights that the impact of bond features on ESG scores and CO2 emissions varies significantly across different types of issuers. Finally, the paper recommends that policymakers strengthen carbon reduction policies, establish mechanisms to prevent greenwashing, and integrate CO2 emissions and ESG factors into assessment systems. Additionally, it calls for special attention to the carbon emissions of entities in low- and middle-income countries, as well as those in the manufacturing sector, to support the healthy development of green finance.
Surface impedance of a metal in the current-carrying state
Authors: Yurkevich I. V. , Yampol’skiĭ V. A.
Published: December 2024

The dependence of the surface impedance of a metal Z on the amplitude of the incident radio wave H and the intensity of the external constant magnetic field h0 is studied theoretically. The cases of weak and strong nonlinearity are studied. The dynamics of the change in the form of the hysteresis loops Z(h0) with increasing amplitude H is studied. It is shown that even under the conditions of not very strong nonlinearity the effect of the magnetic field of the wave on the impedance Z(h0) is of fundamental importance. The results of the work are in agreement with experimental data.
Negative magnetoresistance of granular indium films
Authors: Belevtsev B. I. , Fomin A. V.
Published: December 2024

It is found that for granular indium films with activated conductivity and complete suppression of Josephson tunneling between the grains the transition of grains into the superconducting state is accompanied by a large additional increase in the resistance as the temperature is lowered. A magnetic field weakens this effect, which leads to anomalously large negative magnetoresistance. A qualitative explanation of this effect, taking into account the decrease in the number of normal electrons in the grains as they make the transition into the superconducting state, is given.
Contribution to the electrodynamics of quasi-one-dimensional Peierls dielectrics
Authors: Krive I. V. , Rozhavskiĭ A. S.
Published: December 2024

We construct a continuum model of a Peierls dielectric with an arbitrary commensurability in a de electric field and we study the field and concentration dependences of the soliton conductivity of the charge-density waves. For the first time an explanation is given for the threshold dependence of the conductivity on the electric field and the universal relation between the threshold field and the dielectric constant of the material. The continuum model of a Peierls dielectric is compared to the models of one-dimensional quantum field theory. The results of analysis provide an explanation for the data from low-temperature conductivity measurements of transition-metal trichalcogenides.
Phase diagram of BaMnF4 in the region of the bicritical point
Authors: Anders A. G. , Volotskii S. V. , Zvyagin A. I.
Published: December 2024

The temperature dependence of the field of the transition into the spin-flop phase is studied for the quasi-two-dimensional antiferromagnet BaMnF4. The field of the spin-flop transition at zero temperature, the coordinates of the bicritical point, and other parameters are determined. The position of the boundary between the collinear and paramagnetic phases is predicted.
Magnetic phase diagram of Hg1−xMnxSe
Authors: Brandt N. B. , Ismailov Zh. T. , Kul’bachinskiĭ V. A. , Chudinov S. M. , Gavaleshko N. P. , Mar’yanchuk P. D.
Published: December 2024

The magnetic and electrical properties of single crystal samples of Hg1−xMnxSe have been studied over the temperature range from 0.05 to 4.2 K and a magnetic phase diagram has been constructed as a function of temperature and composition. It is shown that the transition from the the paramagnetic phase to the spin-glass phase is observed for all concentrations of Mn (0≤ x ≤0.385) for which Hg1−x Mnx Se crystallizes in the zinc blende structure.
Resonance coupling of electromagnetic field spikes in thin conductors
Authors: Kardenas V. , Lur'e M. A. , Peschanskii V. G.
Published: December 2024

Three new high-frequency resonance effects in the transmission and impedance of thin films, whose observation will enable us to obtain detailed information on the spectrum and relaxation properties of conduction electrons in a metal, are predicted.
New type of magnetic exchange-relativistic spiral
Authors: Chupis I. E.
Published: December 2024

It is demonstrated that a spiral structure with colinear orientations of the magnetization m and the antiferromagnetism vector 1 can exist in magnets as a result of energy invariants of the type 1 curlm.
Hydrogen–deuterium solid solutions. Quantum diffusion, heat capacity, and conversion
Authors: Bagatskiĭ M. I. , Minchina I. Ya. , Manzheliĭ V. G. , Krivchikov A. I.
Published: December 2024

Hydrogen–deuterium solid solutions with ortho-hydrogen, ortho-deuterium, and para-deuterium concentrations of 0.2−1, 2−30, and 0.03−0.45 mole %, respectively, are studied by calorimetric methods in the temperature range 0.5−6° K. The characteristic time of configurational relaxation is found as functions of the temperature and the concentration. It is shown that, in accordance with the predictions of the theory, the influence of heavy isotopic impurities on the heat capacity of a hydrogen quantum crystal can be described in the harmonic approximation on the assumption that the bonding forces between the impurity molecule and the matrix increase. A comparison is made of the experimental and theoretical values of the heat released as a result of conversion in hydrogen–deuterium solid solutions.
Study of weakly linked superconducting contacts based on tin whiskers
Authors: Golovashkin A. I. , Ivanenko O. M. , Mitsen K. V.
Published: December 2024

Josephson weakly linked contacts based on single-crystal tin whiskers were prepared and studied. Their thermal state was studied. It was found that the temperature dependence of the critical current of such weak links is in good quantitative agreement with the Kulik–mel’yanchuk theory for superconductor-opening-superconductor (SOS) contacts. A distinctive feature of the current-voltage characteristics (IVC) of the contacts studied in the resistive state is the presence of an initial linear section with a low differential resistance. A model relating the appearance of the indicated feature on the IVC to the contribution of nondissipative current flow of quasiparticles is proposed. The nonstationary Josephson properties of the contacts are studied. Current steps induced by microwave irradiation on the IVC were observed up to voltages exceeding 2Δ/e.
Effect of Abrikosov vortices on the properties of superconducting tunnel junctions
Authors: Golubov A. A. , Kupriyanov M. Yu.
Published: December 2024

The properties of tunnel junctions in a magnetic field, oriented perpendicular to the plane of the electrodes, are studied theoretically. The amplitudes of the components of the tunneling current density in the temperature range 0 ≤ T ≤ Tc and magnetic fields 0 ≤ H ≤ Hc2 are determined numerically. It is shown that, in agreement with experiment, increasing the magnetic field increases the amplitude of the quasiparticle current at low voltages V < 2Δ (T)/e and suppresses the supercurrent and interference current. In addition, the curves of the differential conductivity have at V ≃ Δ(T)/e features in the form of a “knee” at temperatures T ≪ Tc. Comparison with experiment enables estimating the value of the field Hc2 of the superconducting electrodes of the contact.
“High-temperature” oscillations of the thermoelectromotive force
Authors: Bogod Yu. A. , Krasovitskiĭ Vit. B. , Lemeshevskaya E. T.
Published: December 2024

The paper reports the first observation of “high-temperature” oscillations of Seebeck coefficients in a magnetic field.
Stability of a charged helium film
Authors: Tatarskii V. V.
Published: December 2024

The behavior of a thin charged helium film is studied with allowance for the change in the film thickness under electron pressure. It is shown that when the real thickness of the film is taken into account, a considerable change is found in the behavior of the critical electron concentration, which ceases to depend on the initial film thickness d in the region of small film thicknesses.
Surface impedance of superconductors with nonideal boundaries
Authors: Buldovskiĭ V. A. , Kulik I. O.
Published: December 2024

The current in a superconducting half-space, depending on the frequency and specularity parameter, is calculated by the method of quasiclassical trajectories. The dependence of the imaginary part of the surface impedance on the specularity parameter is found for frequencies less than the gap width. It is shown that the penetration depth and impedance of clean superconductors, in cases of diffuse and specular reflection, can differ by an amount of the order of 17%. The dependence of the penetration depth of superconductors on the specularity parameter in the nonlocal limit is analogous to that obtained by Hartmann and Luttinger for the anomalous skin effect.
Phase diagrams of easy-axis antiferromagnets with a Dzyaloshinskiĭ interaction field in an inclined field
Authors: Bogdanov A. N.
Published: December 2024

We calculate the ground state of easy-axis antiferromagnets with Dzyaloshinskiĭ interaction in a magnetic field that deviates from the easy axis. The phase diagrams of such magnetic materials are plotted in field-angle coordinates. A first-order phase transition to a weakly ferromagnetic phase is shown to occur in hematite below the Morin temperature.
Surface impedance and surface superconductivity of lead in an inclined magnetic field
Authors: Dzhordzhishvili L. I.
Published: December 2024

It has been shown experimentally that as the angle of inclination of the magnetic field to the surface of a lead single crystal in the state of surface superconductivity increases, the derivative of the real part of the surface impedance dR/dH decreases strongly and vanishes beneath the noise at angles of inclination of 15−25°.
Thermal conductance of metallic point contacts
Authors: Shklyarevskiĭ O. I. , Jansen A. G. M. , Wyder P.
Published: December 2024

Measurements have been carried out between 4.2 and 140° K of the heat flux Q across Au–Au point contacts. A purely electronic mechanism for heat flow across a mechanical contact between two metal electrodes has been realized for the first time. It is shown that the temperature dependence Q(T) for T ≥ 25−30° K is determined by the relation between the electron mean free path, l, and the diameter of the point contact, d, approaching quadratic as 1/d is increased. Measurements of Q(T) and RV(T) enable the temperature dependence of the Lorenz number to be determined for a microcontact and also to estimate its diameter.
Resonance properties of a four-sublattice orthorhombic antiferromagnet in fields perpendicular to the easy axis
Authors: Pashkevich Yu. G. , Sobolev V. L. , Shakhov V. V.
Published: December 2024

The ground states and the frequency-field dependences of antiferromagnetic resonance in a four-lattice orthorhombic antiferromagnet are studied in fields that are greater than the exchange fields and directed along the symmetry axes and perpendicular to the easy axis of the crystal. The region of strong interaction, between the exchange and acoustic modes of the same symmetry is examined and the smallest separation between frequencies is shown to be proportional to the Dzyaloshinskiĭ–Moriya exchange constant and the off-diagonal components of the g-factor tensor. The radio-frequency susceptibility of the antiferromagnet in the spin-flip phase is found and the absorption rate in the exchange mode is considered for a collinear magnetic structure. Distinctive features of the Dzyaloshinskiĭ–Moriya interaction are discussed in the analysis of the exchange modes.
High-frequency properties of a metal with a quasi-two-dimensional electron spectrum
Authors: Gokhfel’d V. M. , Kaganov M. I. , Peschanskii V. G.
Published: December 2024

The anomalous damping of an alternating electric field and propagation of a longitudinal sound wave in a metal, whose quasi-two-dimensional static conductivity is assumed to be determined by the form of its Fermi surface—an open, slightly fluted cylinder—are studied. A number of characteristic differences from the high-frequency properties of a three-dimensional conductor are predicted. The effect of surface scattering of conduction electrons is discussed.
Symmetry of magnetoelastic interaction in hexagonal perovskites
Authors: Vitebskiĭ I. M. , Lavrinenko N. M.
Published: December 2024

The coupling of acoustic and exchange magnons with the elastic subsystem in hexagonal perovskites, which have a noncollinear antiferromagnetic structure of the triangular type, is studied. General conclusions are drawn about the features of the magnetoelastic interaction in antiferromagnets with a noncollinear structure of exchange origin. The existence of linear magnetoelastic and piezomagnetic effects of exchange origin is predicted.
Transition of a Bloch domain wall in a magnetic field into a Néel boundary in BaFe12O19 (NMR data)
Authors: Kuntsevich S. P. , Bezlepkin A. A.
Published: December 2024

A stationary method is used to study the NMR spectrum of 57Fe nuclei in domain walls (DW) of the hexaferrite BaFel2O19 at 77 and 4.2 K. It is shown that the spectrum consists of ten lines, corresponding to five crystallographically nonequivalent positions of the Fe3+ ions at the edge and in the center of the DW. The values of the NMR frequencies of nuclei at the edge of the DW (νd) and at the center of the DW (νw) are presented. The anisotropy of the local NMR frequencies of nuclei in the DW δν = νw − νd is determined. The change in the anisotropy of local NMR frequencies as the temperature increases is explained by a mechanism associated with the presence of intrawall magnons. The effect of a magnetic field on the NMR spectrum in DW is studied. It is found that the NMR line of nuclei in the center of the DW splits into two lines when a magnetic field is applied perpendicular to the direction of easy magnetization. The splitting is linked with the presence of the DW, whose plane can be both parallel and perpendicular to the applied field. The experimental results obtained indicate that for walls perpendicular to the field a transition occurs from the Bloch spin distribution to a Néel distribution in fields H≃4−5 kOe.
Generation of high-frequency phonons with excitation of antiferromagnets by nonresonant parallel pumping
Authors: Sapogov S. A. , Seminozhenko V. P. , Slezova Zh. V. , Sobolev V. L.
Published: December 2024

The generation of high-frequency phonons under the action of an alternating magnetic field with frequency Ω < 2ϵ0 (ϵ0 is the activation energy of the low-frequency branch of the spin wave spectrum) parallel to a constant field on an antiferromagnet is studied. It is shown that phonon generation occurs owing to the induction of magnon-phonon interactions by the alternating magnetic field. The sound waves, whose velocity is greater than the velocity of the spin wave, are generated in a narrow spectral region (its width is determined by the frequency of the alternating magnetic field). Phonons whose frequency exceeds the magnetic field frequency are generated in antiferromagnets in which the spin-wave velocity exceeds the sound velocity.
Transformations of topological defects of superfluid 3He under magnetic field variations
Authors: Ovid’ko I. A.
Published: December 2024

Using the methods of algebraic topology, we study the transformations of topologically stable defects and particle-like solitons in superfluid 3He.
An animal model recapitulates human hepatic diseases associated with
GATA6
mutations
Authors: Shi Wenpeng , Yi Xiaogui , Ruan Hua , Wang Donglei , Wu Dan , Jiang Pengfei , Luo Lisha , Ma Xirui , Jiang Faming , Li Cairui , Wu Weinan , Luo Lingfei , Li Li , Wang Guixue , Qiu Juhui , Huang Honghui
Published: December 2024

Heterozygotic
GATA6
mutations are responsible for various congenital diseases in the heart, pancreas, liver, and other organs in humans. However, there is lack of an animal that can comprehensively model these diseases since GATA6 is essential for early embryogenesis. Here, we report the establishment of a
gata6
knockout zebrafish which recapitulates most of the symptoms in patients with
GATA6
mutations, including cardiac outflow tract defects, pancreatic hypoplasia/agenesis, gallbladder agenesis, and various liver diseases. Particularly in the liver, the zebrafish
gata6
model exhibits the paucity of intrahepatic bile ducts, disrupted bile canaliculi, cholestasis, resembling the liver diseases associated with
GATA6
mutations. Moreover, an unreported phenotype, hepatic cysts, has been also revealed in the model. Mechanistically, Gata6 interacts with Hhex and binds
lrh-1
promoter to synergistically activate its expression, thereby enhancing the Lrh-1-mediated β-catenin signaling which is essential for liver development. This transcriptional activation of
lrh-1
is tightly controlled by the negative feedback, in which Lrh1 interacts with Gata6 to weaken its transactivation ability. Moreover, Gata6 level is regulated by Hhex-mediated proteasomal degradation. The orchestration by these three transcription factors precisely modulates Gata6 activity, ensuring β-catenin signaling output and proper liver development in zebrafish. Importantly, the molecular mechanism identified in zebrafish is conserved in human cells. GATA6 mutant variants associated with hepatobiliary malformations in humans interact aberrantly with HHEX, resulting in subsequent impairments of
LRH-1
activation. Conclusively, the disease model established here provides both phenotypic and mechanism insights into the human hepatic diseases associated with
GATA6
mutations.
Trojan horse peptide conjugates remodel the activity spectrum of clinical antibiotics
Authors: Luo Shangwen , Li Xin-Rong , Gong Xiao-Tong , Kulikovsky Alexey , Qu Feng , Beis Konstantinos , Severinov Konstantin , Dubiley Svetlana , Feng Xinxin , Dong Shi-Hui , Nair Satish K.
Published: December 2024

Infections caused by gram-negative pathogens continue to be a major risk to human health because of the innate antibiotic resistance endowed by their unique cell membrane architecture. Nature has developed an elegant solution to target gram-negative strains, namely by conjugating toxic antibiotic warheads to a suitable carrier to facilitate the active import of the drug to a specific target organism. Microcin C7 (McC) is a Trojan horse peptide–conjugated antibiotic that specifically targets enterobacteria by exploiting active import through oligopeptide transport systems. Here, we characterize the molecular mechanism of McC recognition by YejA, the solute binding protein of the
Escherichia coli
oligopeptide transporter. Structure-guided mutational and functional analysis elucidates the determinants of substrate recognition. We demonstrate that the peptide carrier can serve as a passport for the entry of molecules that are otherwise not taken into
E. coli
cells. We show that peptide conjugation can remodel the antibiotic spectrum of clinically relevant parent compounds. Bioinformatics analysis reveals a broad distribution of YejA-like transporters in only the Proteobacteria, underscoring the potential for the development of Trojan horse antibiotics that are actively imported into such gram-negative bacteria.
Memory control deficits in the sleep-deprived human brain
Authors: Harrington Marcus O. , Karapanagiotidis Theodoros , Phillips Lauryn , Smallwood Jonathan , Anderson Michael C. , Cairney Scott A.
Published: December 2024

Sleep disturbances are associated with intrusive memories, but the neurocognitive mechanisms underpinning this relationship are poorly understood. Here, we show that sleep deprivation disrupts prefrontal inhibition of memory retrieval, and that the overnight restoration of this inhibitory mechanism is associated with time spent in rapid eye movement (REM) sleep. The functional impairments arising from sleep deprivation are linked to a behavioral deficit in the ability to downregulate unwanted memories, and coincide with a deterioration of deliberate patterns of self-generated thought. We conclude that sleep deprivation gives rise to intrusive memories via the disruption of neural circuits governing mnemonic inhibitory control, which may rely on REM sleep.
Dynamic binding of the bacterial chaperone Trigger factor to translating ribosomes in
Escherichia coli
Authors: Hävermark Tora , Metelev Mikhail , Lundin Erik , Volkov Ivan L. , Johansson Magnus
Published: December 2024

The bacterial chaperone Trigger factor (TF) binds to ribosome-nascent chain complexes (RNCs) and cotranslationally aids the folding of proteins in bacteria. Decades of studies have given a broad, but often conflicting, description of the substrate specificity of TF, its RNC-binding dynamics, and competition with other RNC-binding factors, such as the Signal Recognition Particle (SRP). Previous RNC-binding kinetics experiments were commonly conducted on stalled RNCs in reconstituted systems, and consequently, may not be representative of the interaction of TF with ribosomes translating mRNA in the cytoplasm of the cell. Here, we used single-particle tracking (SPT) to measure TF binding to actively translating ribosomes inside living
Escherichia coli
. In cells, TF displays distinct binding modes—longer (ca 1 s) and shorter (ca 50 ms) RNC bindings. Consequently, we conclude that TF, on average, stays bound to the RNC for only a fraction of the translation cycle. Further, binding events are interrupted only by transient excursions to a freely diffusing state (ca 40 ms), suggesting a highly dynamic binding and unbinding cycle of TF in vivo. We also show that TF competes with SRP for RNC binding, and in doing so, tunes the binding selectivity of SRP.
Molecular basis of Spns1-mediated lysophospholipid transport from the lysosome
Authors: Chen Hongwen , Ha Hoa T. T. , Elghobashi-Meinhardt Nadia , Le Nhung A. , Schmiege Philip , Nguyen Long N. , Li Xiaochun
Published: December 2024

Spns1 mediates the rate-limiting efflux of lysophospholipids from the lysosome to the cytosol. Deficiency of Spns1 is associated with embryonic senescence, as well as liver and skeletal muscle atrophy in animal models. However, the mechanisms by which Spns1 transports lysophospholipid and proton sensing remain unclear. Here, we present a cryogenic electron microscopy structure of human Spns1 in lysophosphatidylcholine (LPC)-bound lumen-facing conformation. Notably, LPC snugly binds within the luminal-open cavity, where the molecular dynamics simulations reveal that LPC presents a propensity to enter between transmembrane-helices (TM) 5 and 8. Structural comparisons and cell-based transport assays uncover several pivotal residues at TM 5/8 that orchestrate the transport cycle, which are unique to Spns1. Furthermore, we identify a five-residue network that is crucial for proton-sensing by Spns1. Transference of these network residues to Spns2, a sphingosine-1-phosphate uniporter, causes the chimeric Spns2 to be low pH dependent. Our results reveal molecular insights into lysosomal LPC transport and the proton-sensing mechanism by Spns1.
Reconciling heterogeneous dengue virus infection risk estimates from different study designs
Authors: Huang Angkana T. , Buddhari Darunee , Kaewhiran Surachai , Iamsirithaworn Sopon , Khampaen Direk , Farmer Aaron , Fernandez Stefan , Thomas Stephen J. , Rodriguez-Barraquer Isabel , Hunsawong Taweewun , Srikiatkhachorn Anon , Ribeiro dos Santos Gabriel , O’Driscoll Megan , Hamins-Puertolas Marco , Endy Timothy , Rothman Alan L. , Cummings Derek A. T. , Anderson Kathryn , Salje Henrik
Published: December 2024

Uncovering rates at which susceptible individuals become infected with a pathogen, i.e., the force of infection (FOI), is essential for assessing transmission risk and reconstructing distribution of immunity in a population. For dengue, reconstructing exposure and susceptibility statuses from the measured FOI is of particular significance as prior exposure is a strong risk factor for severe disease. FOI can be measured via many study designs. Longitudinal serology is considered gold standard measurements, as they directly track the transition of seronegative individuals to seropositive due to incident infections (seroincidence). Cross-sectional serology can provide estimates of FOI by contrasting seroprevalence across ages. Age of reported cases can also be used to infer FOI. Agreement of these measurements, however, has not been assessed. Using 26 y of data from cohort studies and hospital-attended cases from Kamphaeng Phet province, Thailand, we found FOI estimates from the three sources to be highly inconsistent. Annual FOI estimates from seroincidence were 1.75 to 4.05 times higher than case-derived FOI. Seroprevalence-derived was moderately correlated with case-derived FOI (correlation coefficient = 0.47) with slightly lower estimates. Through extensive simulations and theoretical analysis, we show that incongruences between methods can result from failing to account for dengue antibody kinetics, assay noise, and heterogeneity in FOI across ages. Extending standard inference models to include these processes reconciled the FOI and susceptibility estimates. Our results highlight the importance of comparing inferences across multiple data types to uncover additional insights not attainable through a single data type/analysis.
Molecular basis of hemoglobin binding and heme removal in
Corynebacterium diphtheriae
Authors: Mahoney Brendan J. , Lyman Lindsey R. , Ford Jordan , Soule Jess , Cheung Nicole A. , Goring Andrew K. , Ellis-Guardiola Kat , Collazo Michael J. , Cascio Duilio , Ton-That Hung , Schmitt Michael P. , Clubb Robert T.
Published: December 2024

To successfully mount infections, nearly all bacterial pathogens must acquire iron, a key metal cofactor that primarily resides within human hemoglobin.
Corynebacterium diphtheriae
causes the life-threatening respiratory disease diphtheria and captures hemoglobin for iron scavenging using the surface-displayed receptor HbpA. Here, we show using X-ray crystallography, NMR, and in situ binding measurements that
C. diphtheriae
selectively captures iron-loaded hemoglobin by partially ensconcing the heme molecules of its α subunits. Quantitative growth and heme release measurements are compatible with
C. diphtheriae
acquiring heme passively released from hemoglobin’s β subunits. We propose a model in which HbpA and heme-binding receptors collectively function on the
C. diphtheriae
surface to capture hemoglobin and its spontaneously released heme. Acquisition mechanisms that exploit the propensity of hemoglobin’s β subunit to release heme likely represent a common strategy used by bacterial pathogens to obtain iron during infections.
Aberrant neuronal hyperactivation causes an age-dependent behavioral decline in
Caenorhabditis elegans
Authors: Aleogho Binta Maria , Mohri Mizuho , Jang Moon Sun , Tsukada Sachio , Al-Hebri Yana , Matsuyama Hironori J. , Tsukada Yuki , Mori Ikue , Noma Kentaro
Published: December 2024

Age-dependent sensory impairment, memory loss, and cognitive decline are generally attributed to neuron loss, synaptic dysfunction, and decreased neuronal activities over time. Concurrently, increased neuronal activity is reported in humans and other organisms during aging. However, it is unclear whether neuronal hyperactivity is the cause of cognitive impairment or a compensatory mechanism of circuit dysfunction. The roundworm
Caenorhabditis elegans
exhibits age-dependent declines in an associative learning behavior called thermotaxis, in which its temperature preference on a thermal gradient is contingent on food availability during its cultivation. Cell ablation and calcium imaging demonstrate that the major thermosensory circuit consisting of AFD thermosensory neuron and AIY interneuron is relatively intact in aged animals. On the other hand, ablation of either AWC sensory neurons or AIA interneurons ameliorates the age-dependent thermotaxis decline. Both neurons showed spontaneous and stochastic hyperactivity in aged animals, enhanced by reciprocal communication between AWC and AIA via neurotransmitters and neuropeptides. Our findings suggest that AWC and AIA hyperactivity mediates thermotaxis decline in aged animals. Furthermore, dietary modulation could ameliorate age-dependent thermotaxis decline by suppressing neuronal hyperactivity. We propose that aberrantly enhanced, not diminished, neuronal activities can impair the behavior of aged animals.
Evolution takes multiple paths to evolvability when facing environmental change
Authors: Kumawat Bhaskar , Lalejini Alexander , Acosta Monica M. , Zaman Luis
Published: December 2024

Life at all scales is surprisingly effective at exploiting new opportunities, as demonstrated by the rapid emergence of antimicrobial resistance and novel pathogens. How populations acquire this level of evolvability and the various ways it aids survival are major open questions with direct implications for human health. Here, we use digital evolution to show that changing environments facilitate the simultaneous evolution of high mutation rates and a distribution of mutational effects skewed toward beneficial phenotypes. The evolved mutational neighborhoods allow rapid adaptation to previously encountered environments, whereas higher mutation rates aid adaptation to completely new environmental conditions. By precisely tracking evolving lineages and the phenotypes of their mutants, we show that evolving populations localize on phenotypic boundaries between distinct regions of genotype space. Our results demonstrate how evolution shapes multiple determinants of evolvability concurrently, fine-tuning a population’s adaptive responses to unpredictable or recurrent environmental shifts.