bluuebunny/crossref_metadata_2025 huggingface dataset:
Les affections dentaires et leurs traitements chez le cheval âgé
Authors: Vlaminck Lieven , Nottrott Knut
Published: January 2025

Chez le cheval, les affections dentaires passent fréquemment inaperçues. Le cheval continue à mastiquer sans difficultés apparentes même en présence de maladies parfois sérieuses.
Les chevaux âgés souffrent souvent d’affections dentaires d’origines diverses : anomalies d’usure, parodontite, résorption odonclastique et hypercémentose, …

Un examen minutieux sous tranquillisation appropriée permet d’identifier les problèmes existants.
Le traitement des anomalies d’usure est plutôt conservatif et complété par des adaptations du régime alimentaire.

La parodontite nécessite souvent des traitements répétés et une guérison n’est que rarement atteinte. Des soins réguliers peuvent néanmoins stabiliser le confort dans la bouche.
Les particularités dentaires chez l’âne
Authors: Chabchoud Ahmed , Nasri Imen
Published: January 2025

Les dents jouent un rôle primordial dans la nutrition et le bien-être de l’âne.
L’âne dispose de structures dentaires plus dures que celles du cheval : c’est la première spécificité anatomique. Néanmoins, l’âne possède le même nombre de dents que le cheval : entre 36 et 44 ; la variation est due à la présence ou l’absence des premières prémolaires.
La chronologie d’éruption et de nivellement des dents est traitée par comparaison avec le cheval. Les irrégularités dentaires acquises sont essentiellement représentées chez l’âne par les surdents qui sont souvent en rapport avec un régime alimentaire inadapté.

Le muleton et le bardot sont plus prédisposés que l’ânon à développer des anomalies congénitales au niveau de la cavité buccale et des molaires. Le prognathisme congénital de la mandibule est le plus souvent retrouvé chez l’âne.

Le traitement des irrégularités dentaires nécessite le râpage des dents pour réduire les surdents et les niveler.

L’utilisation du pas d’âne de Hausmann est préconisée chez l’âne avec ou sans contention chimique. Le recours au tord-nez n’est pas toujours suffisante pour la sécurité et le bien-être animal. Deux râpes manuelles (une plate pour les molaires supérieures et une râpe angulaire pour les molaires inférieures) ou la râpe électrique sont préconisées chez l’âne.

L’emploi des anti-inflammatoires non stéroïdiens nécessite au préalable une parfaite connaissance des particularités de la pharmacocinétique des molécules utilisées chez l’âne.
Les actes de dentisteries équines en France
chez le cheval
Authors: Gauchot Jean-Yves , Laugier Claude , Scicluna Claire
Published: January 2025

Désormais en France, plusieurs catégories d’acteurs peuvent réaliser des soins dentaires.

La France est sans doute le seul pays à avoir réussi à légiférer et à encadrer les para-professionnels que sont les techniciens dentaires équins.
Les techniques d’anesthésies locales et régionales pour les procédures dentaires chez le cheval
Authors: Portier Karine , Nottrott Knut
Published: January 2025

Cet article présente la technique d’anesthésie des nerfs mandibulaires, mentonniers, maxillaires et infra-orbitaire qui permettent de désensibiliser tout ou une partie de la mâchoire ou de la mandibule pour réaliser des actes de dentisterie.

Certaines astuces peuvent faciliter la procédure comme l’utilisation d’un prolongateur, l’administration d’autres anesthésies auxiliaires telles que celle de la gencive, la muqueuse ou l’anesthésie intra ligamentaire.

De nombreux facteurs modifient les durées d’action des anesthésiques locaux tels que la taille du nerf, les propriétés physico-chimiques des molécules, le site d’injection, la dose (concentration et volume), la température, le type de fibre nerveuse, les tissus environnants, la position des fibres dans le nerf, le diamètre de la fibre, le degré de myélinisation, la densité et l’état des canaux sodiques.

Les règles de bonne pratique de la réalisation des anesthésies locorégionales sont présentées, comme la mise en place de mesures d’asepsie chirurgicale, vérifier l’absence d’injection intraveineuse ou artérielle, s’assurer de la bonne sédation du cheval afin limiter le risque de réaction à la piqure.

Cela permet de limiter les risques pour le cheval et le praticien.
Kognitive Dysfunktion bei Krebs erfassen – Assessment: FACT-Cog3
Authors: Görmar Fanny
Published: January 2025

Kognitive Beeinträchtigungen sind häufige Begleiter einer Krebsdiagnose. Das Functional Assessment of Cancer Therapy-Cognitive (FACT-Cog) Version 3 bietet wertvolle Einblicke in spezifische Herausforderungen der Betroffenen im Alltag. Der FACT-Cog3 bietet für die Ergotherapie eine valide und reliable Grundlage, um diese Herausforderungen zu erfassen und gezielte Interventionen abzuleiten.
Cementless Short Stems in Total Hip Arthroplasty: Chances and Limits
Authors: Afghanyar Yama , Kutzner Karl Philipp , Pfeil Joachim , Drees Philipp , Rehbein Philipp , Dargel Jens
Published: January 2025

In recent decades, a large number of cementless short stems have been introduced to the market. The concept aims at saving soft tissue using minimally invasive surgery and at the same time preserving as much bone as possible. In particular, the latest generation of short stems, which are implanted using a calcar-guided round-the-corner technique, are attracting increasing attention. An individualised resection level allows individual stem alignment and thus an ideal reconstruction of the hip anatomy. The early clinical results of short-stem total hip arthroplasty (THA) are promising and have led to an expansion of the indications and limitations for the use of short stems. In particular, the individual positioning in valgus or varus and the resulting individual metaphyseal or metadiaphyseal anchorage offers various possibilities to reconstruct even abnormal joint morphologies. Consequently, short stems are increasingly used in patients with complex anatomical variations or in cases of osteonecrosis of the femoral head. In some various cases, they can also be used in revision or conversion arthroplasty. In some patients, short stems can also be used after femoral neck fracture. Currently, scientific data on those areas of indication of short-stem THA is scarce.
An Unusual Observation in Metastatic Neuroendocrine Neoplasm: Diffuse Pattern Hepatic [68Ga]Ga-DOTATATE Uptake Related to Micro-metastatic Disease and Discordance between Dual-Tracer PET-CT Findings and MIB-1 Labelling Index
Authors: Baberwal Parth , Sonavane Sunita N. , Basu Sandip
Published: January 2025

Neuroendocrine neoplasms (NENs) are a rare and diverse group of neoplasms that can originate from neuroendocrine cells in any organ. We herein present a patient with Grade II neuroendocrine tumor (NET) of the pancreas with bilobar liver metastasis and a MIB-1 labelling index of 15%, who underwent various systemic and targeted therapies. On follow-up, dual-tracer PET-CT imaging with [68Ga]Ga-DOTATATE PET/CT showed new onset skeletal metastases and diffuse pattern SSTR (somatostatin receptor) expression in the left lobe of the liver (Krenning score 3), contrasted by absent uptake on [18F]FDG. Magnetic resonance imaging of the liver confirmed sub-centimetric left liver lobe lesions, further biopsy of which suggested Grade-III NET exhibiting high Ki-67 (55–60%). Thus, a discordance was observed between Ki-67 and the dual-tracer PET-CT findings, emphasizing the complexity of NEN imaging (with possibility of differentiation even in a relatively high Ki-67) and the importance of using multiple tracers for accurate assessment in guiding evidence-based management strategy.
Improving ocular drug delivery with liposomes
Authors: Thompson Avery
Published: January 2025

Nanocarriers offer a drug delivery method that is less invasive, more accurate, and has fewer side effects.
E-mode AlGaN/GaN HEMT with ScAlN/ScN charge trap-coupled ferroelectric gate stacks
Authors: Liu Jiangnan , Wang Ding , Hasan Md Tanvir , Mondal Shubham , Manassa Jason , Shen Jeremy M. , Wang Danhao , Tanim Md Mehedi Hasan , Yang Samuel , Hovden Robert , Mi Zetian
Published: January 2025

A fully epitaxial ferroelectric ScAlN/AlGaN/GaN HEMT coupled with an ultrathin ScN charge trap layer for enhancement-mode operation is demonstrated. The ultrathin ScN acts as an electron reservoir to trap and store the electrons from the 2-dimensional electron gas channel region, transitioning the operation of the GaN high electron mobility transistor from the depletion-mode to the enhancement-mode, while the fully epitaxial nature enables low interface defect density and steep slope operation. The initialization process by applying a positive gate bias to inject carriers to the ScN layer is observed to shift the threshold voltage (Vth) from −1.2 to +1.3 V. The fabricated device also shows a steep subthreshold swing as low as 61 mV/dec and exhibits good stability, providing a promising pathway for power-efficient and multifunctional applications.
Investigation of a flat-type piezoelectric motor using in-plane vibrations
Authors: Li Chong , Lu Cunyue
Published: January 2025

This paper presents a flat-type piezoelectric motor utilizing in-plane vibration modes. Two piezoelectric ceramic plates in combination with a brass metal sheet were used to construct the stator. The superposition of two second order in-plane vibration modes can generate a traveling-wave inside the stator. The greatest advantage of the proposed motor lies in its sheet structure configuration, which significantly reduces the overall size of piezoelectric motors exploiting in-plane vibrations, particularly in terms of thickness. Meanwhile, the stator also demonstrates greater vibration displacements when compared to higher-order operating modes. Through discussing the impact of stator structure parameters on the vibration deflection angle θ, the excitation ways of operating modes were investigated. Subsequently, the finite element method was utilized to explore both the static and dynamic vibration properties of the stator. Simulation results suggest that at a steady state, stator driving points achieve vibrations at the micro-meter level, satisfying actual application requirements. Finally, a prototype motor was fabricated. Driven by two-phase alternating voltage with a frequency of 69.4 kHz, the no-load speed and stall torque of the prototype motor are 52 rpm and 3.2 mN m, respectively.
Active alignment control system for thin disk regenerative amplifier
Authors: Horáček J. , Hubka L. , Chyla M. , Mocek T.
Published: January 2025

We present an active alignment and stabilization control system for laser setups based on a thin-disk regenerative amplifier. This method eliminates power and pointing instability during the warm-up period and improves long-term stability throughout the entire operation. The alignment method is based on a four-mirror control system consisting of two motorized mirrors placed within the regenerative amplifier cavity, two additional motorized mirrors external to the amplifier cavity, and four camera detectors. The implemented stabilization system achieves significant performance improvements, increasing the power stability from 1.87% to 0.79% RMS and the peak-to-peak stability from 7.43% to 3.88%. Furthermore, the system significantly enhances beam positional stability, achieving up to a sixfold improvement in certain sensor measurements. The advantage of this method is the removal of long-term pointing instability by adding a second controlled motorized mirror to the cavity, in addition to using only one cavity end mirror for optimizing the overlap with the pump spot on the cavity medium. To achieve higher precision in pointing, the nonlinear hysteresis effect of the piezoelectric actuator is mitigated. Although the power and pointing stability of the cavity are secured, pointing instability at the input of the compressor occurs. This issue is resolved by two additional controlled motorized mirrors external to the cavity.
The role of spin diffusion in endogenous metal ions DNP
Authors: Moroz Ilia B. , Jardón-Álvarez Daniel , Leskes Michal
Published: January 2025

The sensitivity of solid state nuclear magnetic resonance spectroscopy can be enhanced via dynamic nuclear polarization (DNP) using unpaired electrons as polarizing agents. In metal ions based (MI)-DNP, paramagnetic metal ions are introduced as dopants into inorganic materials serving as endogenous polarizing agents. Having polarizing agents as part of the structure enables signal enhancements within the bulk of the material. Nuclear spins can be hyperpolarized either directly through their coupling to the polarizing agent or via homonuclear spin diffusion. In this work, we addressed what are the factors determining the relative sizes of the spin pools polarized by each of these two mechanisms and how changing their contribution to the polarization process affects the experimental outcome. Experimentally, we adjusted the spin diffusion rate through modifying the isotope ratio 6Li/7Li in otherwise identical samples, Li4Ti5O12 doped with paramagnetic Fe(III). DNP experiments on samples with typical content of polarizing agents for MI-DNP, corroborated by simulations, evidenced that while the efficiency of spin diffusion has large effects on the polarization buildup times, the enhancements remain largely unaffected.
A class of n-D Hamiltonian conservative chaotic systems with three-terminal memristor: Modeling, dynamical analysis, and FPGA implementation
Authors: Yuan Ye , Yu Fei , Tan Bohong , Huang Yuanyuan , Yao Wei , Cai Shuo , Lin Hairong
Published: January 2025

Memristors are commonly used to introduce various chaotic systems and can be used to enhance their chaotic characteristics. However, due to the strict construction conditions of Hamiltonian systems, there has been limited research on the development of memristive Hamiltonian conservative chaotic systems (MHCCSs). In this work, a method for constructing three-terminal memristors is proposed, and the three-terminal memristors are incorporated into the Hamiltonian system, resulting in the development of a class of n-D MHCCS. Based on this method, we model a 4D MHCCS as a standard model for detailed dynamic analysis. The dynamic analysis reveals that the MHCCS exhibits complex dynamic behaviors, including conservativeness, symmetry, chaos depending on parameters, extreme multistability, and chaos under a wide parameter range. The dynamic analysis shows that MHCCS not only retains the favorable characteristics of a conservative system but also has more complex nonlinear dynamics due to the incorporation of memristors, thereby further enhancing its chaotic characteristics. Furthermore, the pseudo-random number generator based on the MHCCS has excellent randomness in terms of the NIST test. Finally, the physical realizability of the system is verified through Field Programmable Gate Array experiments. This study demonstrates that the constructed class of MHCCSs is a good entropy source that can be applied to various chaotic embedded systems, including secure communication, cryptographic system, and pseudo-random number generator.
Luminescence efficiency and temperature quenching of spontaneous and stimulated emission in ultra-low dislocation density InN
Authors: Andreev B. A. , Kudryavtsev K. E. , Yablonskiy A. N. , Lobanov D. N. , Novikov A. V. , Liu H. P. , Sheng B. , Wang X. Q.
Published: January 2025

In this letter, we evaluate temperature quenching of photoluminescence in ultra-high quality epitaxial InN films to assess the internal quantum efficiency (IQE) of band-to-band light emission. Measured room-temperature carrier lifetimes of ∼10 ns in the samples with record-low dislocation density of Nd ∼ 5 × 108 cm−2 appear consistent with the diffusion-limited Shockley–Reed–Hall recombination model and lead to a maximum emission IQE of ∼1.5% at T = 300 K. For the stimulated emission (SE) regime, dislocation densities in excess of 1010 cm−2 can be actually tolerated without seriously affecting the SE threshold, and its temperature dependence is determined by a competition between radiative and Auger processes, with a crossover point around liquid-nitrogen temperature.
Experimental investigations on the trigger characteristics of a cold-cathode plasma discharge switch with grid voltage control
Authors: Zhang Yushi , Sun Hao , Liu Tianxiao , Wu Yi , Niu Chunping
Published: January 2025

The cold-cathode plasma discharge switch is a switching device capable of conducting and interrupting currents. It has the potential to replace fully controllable power semiconductor devices in the field of direct current power transmission. The switch primarily consists of four electrodes: anode, control grid, source grid, and cathode. By applying voltage to the source grid, a magnetized source plasma is generated. Applying a positive voltage to the control grid facilitates the charged particle motion, forming a stable conduction path from anode to cathode. Conversely, applying a negative voltage to the control grid creates a sheath within the grid's apertures to achieve current interruption. We developed a flat-type cold-cathode plasma discharge switch and investigated the effects of source plasma discharge current, electrode spacing, and anode voltage on its trigger characteristics. This type of plasma switch relies on control grid voltage to regulate plasma, and the trigger time is largely determined by the charged particle motion. The source plasma provides a sufficient supply of charged particles, which is essential for switch conduction. Reducing the “source grid–control grid” gap can significantly shorten the trigger time. Increasing the anode voltage enhances the electric field strength across the gap, accelerating the charged particle motion into the “anode-control grid” region. The impact of the control grid current on switch performance and the mechanism for low-voltage plasma conduction are discussed. Additionally, further device miniaturization is necessary to enhance insulation strength on the left side of the Paschen curve and reduce its trigger time.
Advancements and challenges in sodium borohydride hydrogen storage: A comprehensive review of hydrolysis, regeneration, and recycling technologies
Authors: Chin Siew Xian , Vincent Jei , Razak Nor Farhah , Daud Nurulhaidah , Chowdhury Shahriah , Wongchoosuk Chatchawal , Chia Chin Hua
Published: January 2025

Hydrogen's potential as a clean energy carrier is increasingly recognized, but its storage remains a significant challenge. Sodium borohydride (NaBH4) stands out as an efficient hydrogen storage medium due to its high gravimetric capacity and safety profile. This review paper provides a comprehensive analysis of the research progress in NaBH4 hydrolysis for hydrogen production from 2004 to 2024. This paper discusses the advantages of NaBH4, including its high hydrogen yield, stability, controlled hydrogen release, and potential for regeneration into NaBH4 from the by-product sodium metaborate. This review surveys various catalysts used to enhance the hydrolysis reaction, such as cobalt, nickel, ruthenium, and noble metals, emphasizing their efficiency, recyclability, and economic viability. It also examines the influence of reaction conditions like temperature, pH, and NaBH4 concentration on the hydrolysis process. Additives and modifiers that improve reaction kinetics and hydrogen yield are also discussed. This paper further explores the regeneration and recycling of NaBH4, which is crucial for a sustainable hydrogen economy. It outlines three main approaches: thermochemical, mechanochemical, and electrochemical methods, each with its advantages and challenges. In conclusion, NaBH4 is a compelling hydrogen storage material with ongoing research aimed at overcoming the remaining challenges for its large-scale application. The development of more efficient and sustainable NaBH4 regeneration methods is essential for the future of clean energy.
Topological sonic whispering gallery protected by the synthetic Weyl points
Authors: Wang Zhennan , Huang Zixin , Deng Chengxin , Yang Yuzhen , Zhang Xu , Yang Yiqin , Jia Han , Yu Yingjian , Wang Rongli , Yang Hai
Published: January 2025

The synthetic dimension provides us with a powerful platform to explore the topological properties of matter. In this paper, we choose two physical dimensions (kx and ky) and one geometric structure parameter (the height of the air cavity δ) to construct a synthetic space. The simulation results display that the three couples of Weyl points and Fermi arcs appear in the synthetic space. We find that changing the position of the boundary truncation of a sonic crystal can flexibly regulate the frequency range of valley chiral edge states. Both theoretically and experimentally, we demonstrate the sonic topological valley-locked whispering gallery, in which the valley states propagate along the interfaces between a sonic crystal and a hard wall. In the valley-locked whispering gallery, the sonic waves propagate unidirectionally along the closed channel, with high scattering efficiency and small diffraction.
Molecular engineering charge transfer and triplet exciton formation in donor–acceptor cocrystals
Authors: Williams Malik L. , Palmer Jonathan R. , Tyndall Samuel B. , Chen Yizhe , Young Ryan M. , Garzon-Ramirez Antonio J. , Tempelaar Roel , Wasielewski Michael R.
Published: January 2025

Organic donor–acceptor (D–A) cocrystals are gaining attention for their potential applications in optoelectronic devices. This study explores the dynamics of charge transfer (CT) and triplet exciton formation in various D–A cocrystals. By examining a series of D–A cocrystals composed of coronene (COR), peri-xanthenoxanthene (PXX), and perylene (PER) donors paired with N,N-bis(3′-pentyl)perylene-3,4:9,10-bis(dicarboximide) (PDI), naphthalene-1,4:5,8-tetracarboxy-dianhydride (NDA), or pyrene-4,5,9,10-tetraone (PTO) acceptors, using transient absorption microscopy and time-resolved electron paramagnetic resonance spectroscopy, we find that the strength of the CT interaction influences the nature and yield of triplet excitons produced by CT state recombination. In particular, in the PER-PDI, COR-PTO, and PER-PTO cocrystals, localized triplet excitons are lower in energy than the CT state. By contrast, no localized triplet excitons are available to the CT states of the PXX-NDA, PER-NDA, and PXX-PTO cocrystals, and as a result, the CT states rapidly decay to ground state with no triplet formation. Moreover, density functional theory calculations show that the transition between delocalized CT states to a triplet state localized to a single donor or acceptor unit provides the source of spin–orbit coupling necessary when the triplet states are energetically accessible. These findings provide insights into the design of molecular materials with tailored exciton properties for optoelectronic applications.
Natural convective heat transfer in a square cavity with a curved hot wall partially heated from below
Authors: Zemani Farah , Sabeur Amina , Ladjedel Omar , Chelih Amira
Published: January 2025

This study investigates laminar natural convection within a square enclosure filled with air, with a focus on understanding the impact of different geometries of a partially heated bottom wall. The study is important because optimizing heat transfer in enclosures with varying wall shapes can enhance thermal management in engineering applications. A two-dimensional numerical model was developed using the finite volume method and the Semi-Implicit Method for Pressure-Linked Equations (SIMPLE) algorithm to solve the steady-state Navier–Stokes equations along with the mass and energy conservation equations. The study explores the effect of the Rayleigh number (Ra = 103–106), the width of the heated section (ε = 0.2–0.8), and the height of the curved shapes (h = 0.01L to 0.05L) on convection heat transfer performance. The results show that increasing the heated width (ε) and reducing the height of the curved shapes (h) significantly enhance the average Nusselt number. Specifically, for given values of ε and h, an increase in Rayleigh number leads to a further enhancement in the average Nusselt number. Moreover, the introduction of upward and downward undulations in the heated wall shape generally reduces the average Nusselt number, with downward undulations having a stronger negative effect. This work provides new insights into the influence of wall shape on heat transfer, showing that downward undulations in the heated wall diminish thermal performance, which has not been extensively explored in prior literature.
High performance neural network for solving coronary artery flow velocity field based on fluid component concentration
Authors: Li Bao , Sun Hao , Yang Yang , Fan Luyao , Li Xueke , Liu Jincheng , Li Guangfei , Mao Boyan , Zhang Liyuan , Zhang Yanping , Dong Jinping , Liu Jian , Hou Chang , Wang Lihua , Zhang Honghui , Huang Suqin , Li Tengfei , Kong Liyuan , Wang Zijie , Guo Huanmei , Qiao Aike , Liu Youjun
Published: January 2025

Rapid methods that can replace traditional inefficient computational fluid dynamics (CFD) for solving flow field are missing. We reconstructed three-dimensional (3D) coronary vascular tree models based on coronary computed tomography angiography (CCTA) images from 205 patients. Two fluid materials, blood and contrast agent, were mixed to simulate the flow field with concentration information under diverse boundary conditions, obtaining 2255 CFD simulations as deep learning samples. A dual-path physics-data multi-derived neural network (PDMNN) was designed, inputting geometric 3D point cloud and concentration information, respectively, and outputting 3D flow velocity field. Flow velocity in the coronary artery was clinically measured in 26 patients to verify the proposed PDMNN. For the 100 cases in a test set, the mean square error of the flow field velocity between the CFD calculations and the PDMNN predictions is 0.0309. However, the time taken by the PDMNN is significantly reduced (10 s VS 0.5 h). Clinically measured mean blood flow velocity and PDMNN predictions did not yield statistically significant differences (0.00 ± 0.05 m/s, P > 0.05). The proposed PDMNN present excellent computation accuracy and efficiency, holding a significant technical value for the clinical and engineering application.
Spatial arrangement of vortex-generator-type plasma actuator for separation control of airfoil flow
Authors: Sato Makoto
Published: January 2025

In this study, large-eddy simulations on separated-airfoil-flows controlled using a vortex-generator-type plasma actuator (VG-PA) have been conducted. The flow conditions, airfoil shape, and the configurations of the VG-PA were set based on a previous experimental study by Jukes et al. [AIAA J. 51, 452 (2013)]. The Reynolds number based on the chord length (c) was set at 95 000 with an angle of attack of 18°. The VG-PA spanwise spacing (λ/c) was varied from 0.05 to 0.4. The results show that the improvement in the aerodynamic performances by the VG-PA control is significantly affected by λ/c. The most effective airfoil flow control was achieved at λ/c=0.1. In the controlled cases, large-scale streamwise flow structures were generated by the interaction of the streamwise vortices produced by the VG-PA. These structures were formed with fine-scale three-dimensional turbulent vortices, resulting in negative Reynolds stress and turbulent reattachment. Furthermore, the streamwise vortex generated by the VG-PA in a boundary layer flow was investigated to better understand the distribution of vortices. The streamwise vortex was distributed from the actuator to a point 0.1c away from the actuator in the induced flow direction. This indicates that the most effective airfoil flow control to improve the aerodynamic performances can be achieved when the streamwise vortex generated by the VG-PA collides with the opposite streamwise vortex.
Torque-driven superparamagnetic microbots
Authors: Morozov Konstantin I. , Zusmanovich Dana , Rubinstein Boris Y. , Leshansky Alexander M.
Published: January 2025

Actuation powered by a rotating magnetic field is a promising method of controlled steering of micro(nano)metric synthetic propellers through fluids. Such actuation relies on a magnetic torque, which is a product of the driving field and a dipolar magnetic moment possessed by the micro-/nanopropeller of nontrivial shape allowing for rotation–translation coupling. While ferromagnetic (permanently magnetized) microbots have been studied extensively, superparamagnetic (susceptible to magnetization, not possessing remanent magnetization) did not get as much focus. Here, we present a general theory of torque-driven actuation and steering of magnetically polarizable micropropellers. The steady torque-driven rotation regimes and their stability are considered for microbots assuming cylindrical rotational anisotropy and for arbitrary geometry and orientation of the magnetization easy axis. Furthermore, we study in detail the dynamics of planar microbots made of isotropic superparamagnetic material, for which the magnetic anisotropy is being controlled entirely by the geometry. Planar geometry is interesting from a fundamental point of view (i.e., to establish the minimal requirements for steering of polarizable microbots) and for practical reasons due to easy of microfabrication via standard photolithography. It is demonstrated that stable torque-driven rotation resulting in net propulsion would require high degree of geometric and magnetic asymmetry, e.g., the L-shaped planar propeller with unequal arms, with a shorter arm made of superparamagnetic material, can be efficiently steered by a rotating magnetic field.
Kinetic energy spectrum and transfer within the near-dissipation range of compressible isotropic turbulence
Authors: Yang Guowei , Yan Zheng , Wu Junfeng , Wang Jianchun , Yu Changping , Li Xinliang , Wang Lifeng
Published: January 2025

The analysis of kinetic energy spectrum and dissipation mechanisms plays a crucial role in both theoretical examination and real-world implementations within compressible turbulent flows. The previous works within the near-dissipation range are conducted within the framework of incompressible turbulent flow dynamics. We investigate the kinetic energy spectrum and transfer within the near-dissipation range of compressible isotropic turbulent flows via highly resolved direct numerical simulations with different turbulent Mach numbers (Mt). We found that in compressible turbulent flows, the kinetic energy spectrum model is significantly influenced by the turbulent Mach number, with a more pronounced tail as the turbulent Mach number increases. Within the near-dissipation range, there exist strong local spatial fluctuations of the kinetic energy flux with the increase in grid resolution. The viscous dissipation can be decomposed into solenoidal and dilatational components, and its dilatational component leads to stronger intermittency within the near-dissipation range. Besides, the high turbulent Mach number also leads to a stronger dissipation, which serves as an alternative factor for the high intermittency within the near-dissipation range in compressible turbulent flows. The uncovered high intermittency provides a theoretical foundation for the prediction of intense events and the development of turbulent modelings.
Boundary layer turbulence on the flutter stability of streamlined box girders in long-span bridges
Authors: Liu Jun , Ni Zhifu , Liao Haili , Li Feng , Tian Liyong , Qiu Enxi
Published: January 2025

Long-span bridges are vulnerable to flutter instability, which can lead to catastrophic failure if not properly assessed. Traditional analyses have focused on smooth flow conditions, which do not fully reflect real-world aerodynamic conditions where boundary layer turbulence plays a significant role. This study delves into the flutter characteristics of streamlined box girder bridge decks, focusing on the effects of boundary layer turbulence. A novel analytical approach is introduced, incorporating spanwise correlation of self-excited aerodynamic forces into flutter analysis. Initially, wind tunnel tests involving forced vibration of segmental models were conducted in both smooth and turbulent flows to determine the flutter derivatives of the bridge deck. This was followed by an investigation of flutter critical wind speeds under varying conditions using taut strip model free vibration tests. The highlight of this research is the development of a comprehensive three-dimensional flutter analysis method that integrates the spanwise correlation effect. Findings indicate a significant influence of boundary layer turbulence on the flutter derivatives, with the observed flutter critical wind speeds in turbulent conditions surpassing those in smooth flow. The study also notes a decrease in flutter critical wind speeds with increasing turbulence intensity and integral scale. Importantly, the incorporation of spanwise correlation effects into the analysis yields theoretical flutter critical wind speeds that closely match those observed in wind tunnel experiments. This research contributes to a deeper understanding of aerodynamic behavior in bridge decks under turbulent conditions and enhances predictive capabilities in bridge aerodynamics.
Size-dependent phase change in energy storage materials: Comparing the impact of solid-state wetting and of coherency stress
Authors: Li Yong , Weissmüller Jörg
Published: January 2025

Coherent phase transformations in interstitial solid solutions or intercalation compounds with a miscibility gap are of practical relevance for energy storage materials and specifically for metal hydride or lithium-ion compound nanoparticles. Different conclusions on the size-dependence of the transformation conditions are reached by modeling or theory focusing on the impact of either one (internal, solid-state-) critical-point wetting of the nanoparticle surface or coherency constraints from solute-saturated surface layers. We report a hybrid numerical approach, combining atomistic grand canonical Monte Carlo simulation with a continuum mechanics analysis of coherency stress and modeling simultaneously wetting and mechanical constraints. When the ratio between chemical and misfit-strain-related contributions to the solute-solute interaction energy takes values realistic for interstitial solutions—which are typical for energy storage materials—we find that the impact of solid-state wetting is weak and that of coherency stress is dominant. Specifically, mechanical interaction can act to reduce the phase transformation hysteresis at small system size, and it can make the solid more binding for solute, thereby reducing the “plateau” chemical potential at phase coexistence. We present equations for the impact of coherency stress on the size-dependence of upper consolute temperature, plateau chemical potential, and charging/discharging hysteresis.
Cryogenic hybrid magnonic circuits based on spalled YIG thin films
Authors: Xu Jing , Horn Connor , Jiang Yu , Pishehvar Amin , Li Xinhao , Rosenmann Daniel , Han Xu , Levy Miguel , Guha Supratik , Zhang Xufeng
Published: January 2025

Yttrium iron garnet (YIG) magnonics has garnered significant research interest because of the unique properties of magnons (quasiparticles of collective spin excitation) for signal processing. In particular, hybrid systems based on YIG magnonics show great promise for quantum information science due to their broad frequency tunability and strong compatibility with other platforms. However, their broad applications have been severely constrained by substantial microwave loss in the gadolinium gallium garnet (GGG) substrate at cryogenic temperatures. In this study, we demonstrate that YIG thin films can be spalled from YIG/GGG samples. Our approach is validated by measuring hybrid devices comprising superconducting resonators and spalled YIG films, which exhibit anti-crossing features that indicate strong coupling between magnons and microwave photons. Such new capability of separating YIG thin films from GGG substrates via spalling and the integrated superconductor-YIG devices represent a significant advancement for integrated magnonic devices, paving the way for advanced magnon-based coherent information processing.
The flow field evolution and load characteristics of water-exit of ventilated vehicle constrained by floating ice environment
Authors: Gao Zishu , Lv Hongqing , Wang Zhenqing , Liu Zichu , Xu Lei
Published: January 2025

The water-exit process of a ventilated vehicle in a floating ice environment involves multi-physics coupling characteristics, including multiphase flow, strong turbulence, cavitating flow, and fluid–structure interaction (FSI), making it a highly nonlinear process. This study employs a two-way FSI algorithm that combines computational fluid dynamics and the finite element method to analyze the effects of floating ice quantity, floating ice thickness, and the initial gap between the floating ice and the vehicle on the water-exit process and compares the results with the ice-free condition. The study focuses on the evolution of the flow field, the hydrodynamics characteristics, and the structural dynamic response during the vehicle's water-exit process in the icy environment. The findings indicate that the presence of floating ice significantly affects the vehicle's cross-water stage, causing the cavity on the near-ice side of the vehicle to collapse earlier and intensifying the flow field variations. Compared to the structural dynamic response, the stability of water-exit process is more sensitive to the distribution of the floating ice. When the floating ice is symmetrically distributed, the water-exit process stability is higher. Increasing the thickness of the floating ice accelerates the collapse of the cavity, reduces the stability of the vehicle's water-exit, and exacerbates the high-stress concentration phenomenon. The study also identifies a critical relative distance, beyond which the influence of floating ice on the cavity evolution, emergence stability, and structural dynamic response is significantly reduced.
A 614 MW/cm2 AlGaN-channel Schottky barrier diode with high breakdown voltage and high temperature sensitivity
Authors: Chen Heyuan , Zhang Tao , Su Huake , Li Xiangdong , Xu Shengrui , Zhang Yachao , Liu Ruowei , Xie Lei , Hao Yue , Zhang Jincheng
Published: January 2025

In this work, a high-performance AlGaN-channel Schottky barrier diode with high breakdown voltage of 2.23 kV defined at anode leakage current of 1 μA and high power figure-of-merit of 614 MW/cm2 is demonstrated. Anode voltage (VA) with a clear linear relationship as a function of temperature from 300 to 525 K shows great potential for temperature sensors, and maximum temperature sensitivity of 2.0 mV/K at anode current density (IA) of 6.28 × 10−8 A is obtained, satisfying the low power consumption requirement. Meanwhile, the corresponding temperature sensitivity of ln(–I) vs temperature at a fixed VA of –15 V is 5.0 mA/K, and the suppressed temperature sensitivity at reverse bias is attributed to the energy-band modulated Schottky barrier height of AlGaN-channel M/S interface, which is vital for high-temperature and high-power applications.
Impact of non-isotropy on the statistics of turbulence relative to moving vehicles
Authors: Gao Hongrui , Liu Tanghong , Chen Xiaodong , Zhang Jie , Khoo Boo Cheong
Published: January 2025

The isotropic turbulence assumption, though widely used, may not accurately represent real-world conditions in stochastic wind models for turbulence relative to moving vehicles. This study derives the statistical properties of non-isotropic turbulence relative to moving vehicles, focusing on correlation functions, power spectral densities (PSDs), and coherence functions of wind speed fluctuations. A quantitative parameter characterizing the impact of non-isotropic turbulence is introduced, enabling an in-depth analysis of its effects on turbulence statistics. Non-isotropic turbulence notably increases PSDs in frequency regions critical to vehicle stability under crosswinds, underscoring the need to account for these effects in quantitative assessments. Without considering non-isotropic influences, crosswind stability may be overestimated. Non-isotropic turbulence impacts the PSDs both indirectly, by altering the lateral-to-longitudinal turbulence length scale ratio, and directly, through additional influences on PSDs. Prior studies have largely focused on the indirect effect, but both effects should be considered, as omitting the direct effect results in up to a 28.9% underestimation of PSDs at low frequencies, potentially overestimating running safety. The analysis also reveals that the relative wind angle, defined as the difference between the vehicle's running direction wind angle and its yaw angle, is the primary factor influencing turbulence characteristics, consistent for both isotropic and non-isotropic conditions. Additionally, the spatial correlation of wind speed fluctuations depends largely on the separation distance relative to the longitudinal turbulence length scale. Therefore, in qualitative studies of wind fluctuation effects on crosswind stability, non-isotropic turbulence may be disregarded. This work enhances the accuracy of stochastic wind models across different scenarios, providing a foundation for future research on crosswind safety in railway operations under turbulent wind conditions.
Determining the optical and polaritonic properties of isotopically pure hBN using cryogenic FTIR micro-spectroscopy
Authors: Nandanwar Siddharth , Desai Aditya , Esfidani S. Maryam Vaghefi , McMillan Tristan , Janzen Eli , Edgar James H. , Folland Thomas G.
Published: January 2025

van der Waals materials support numerous exotic polaritonic phenomena originating from their layered structures and associated vibrational and electronic properties. However, many van der Waals materials' unique properties are most prominent at cryogenic temperatures. This presents a particular challenge for polaritonics research, as reliable optical constant data are required for understanding light-matter coupling. This paper presents a cryogenic Fourier transform infrared microscope design constructed entirely from off-the-shelf components and associated fitting procedures for determining optical constants in the infrared. Data correction techniques were developed to directly quantify systematic errors in the fitting procedure. We use this microscope to present the first temperature-dependent characterization of the optical properties of hexagonal boron nitride enriched with isotopically pure boron. Our full analysis of the infrared dielectric function shows small but significant tuning of the optical constants, which is highly consistent with Raman data from the literature. We then use this dielectric data to perform and analyze the polariton propagation properties, which agree exceptionally well with published cryogenic scattering-type near-field microscopy results. In addition to the insights gained into hyperbolic polaritons in hBN, our paper represents a transferable framework for characterizing exfoliated infrared polaritonic materials and other infrared devices. This could accelerate discoveries in different material systems, especially those that are spatially inhomogeneous or cannot be prepared as large single crystals.
A single-domain approach for modeling flow in and around porous media applied to buoyant reacting plume formation and ignition
Authors: Behnoudfar D. , Niemeyer K. E.
Published: January 2025

Many processes involve mixed porous–solid–fluid domains where fluid flow, heat transfer, and chemical reactions interact over disparate length scales, such as the combustion of multi-species solid fuels. Although many studies have concentrated on detailed physics within the fluid or porous phase, few consider both phases, in part due to the challenge in determining suitable boundary conditions between the regions, particularly in turbulent flows where eddies might penetrate the pores. Here, we apply a single-domain approach that eliminates the need for boundary conditions at the interface, and simulate scenarios involving porous solids and a surrounding fluid. Similar to large eddy simulation, the method averages properties over a small spatial volume—but over the entire domain. We focus on ignition and related interfacial phenomena. After verifying and validating the model, we examine the emission of buoyant reacting plumes from the surface of a heated solid and the near-field flow dynamics. The results indicate flow instabilities similar to Rayleigh–Taylor and Kelvin–Helmholtz phenomena. A combination of viscous and baroclinic torques triggers vorticity generation near the interface and its growth in the surrounding fluid region. Furthermore, we explore the effect of interface morphology, finding that geometrical characteristics such as asymmetry or gap size can alter ignition time and location, or even suppress it. Asymmetry-induced oscillations initially cause negative heat fluxes, which prevent the temperature from reaching the critical level necessary to trigger ignition. These behaviors could significantly influence the mixing of oxidizer and fuel, ignition processes, and fire propagation.
Study of auto-igniting spray flame in vitiated swirling hot coflow using flamelet generated model
Authors: Alam Zafar , Bhatia Bharat , De Ashoke
Published: January 2025

Swirl-stabilized auto-igniting spray flames are essential for designing efficient and clean combustion systems. The present study performs large eddy simulations of the dilute auto-igniting methanol flame in a vitiated, hot coflow of varying swirl intensities. The six-dimensional Flamelet Generated Manifold technique is used to solve the reactive flow accurately and economically. The swirl numbers (SN), i.e., 0.2, 0.6, 1.0, and 1.4, are used to assess their effect on auto-ignition and flame stability. At lower to moderate swirl numbers (SN = 0.2, 0.6), the increase in swirl is found to increase the liftoff height. Beyond the critical swirl number (SN = 0.6), the liftoff height drops. Also, the time-averaged flame structure transitions from a tubular-like flame into a uniformly distributed combustion region at these high swirl numbers. It also results in a more compact flame for the higher swirl numbers. These effects on flame dynamics are analyzed in detail using the mean gas-phase flow field distribution, particle statistics, and proper orthogonal decomposition.
Rate transient of the multiply fractured horizontal well in the shale gas reservoir based on the embedded discrete fracture model and topology
Authors: Xing Guoqiang , Wang Qilong , Wang Baohua , Yang Wuyang , Cui Yudong , Zhao Xinli
Published: January 2025

The complex fracture network may be formed by coupling natural fractures (NFs) and hydraulic fractures (HFs) in the shale gas reservoir. In this work, by introducing the topology theory, two types of topological nodes, three types of topological connections, and four types of fracture topologies on the complex fracture network are proposed and, accordingly, the numerical model of the multiply fractured horizontal well (MFHW) is further established based on embedded discrete fracture model and topology analysis. The production analysis shows that large Langmuir volume and pressure contribute to higher production of the gas well under the assumption that the content of free gas in the shale matrix is fixed while the stress sensitivity is unconducive to enhancing the gas well's production due to the decrease in the permeability in the shale matrix and fractures. Meanwhile, it is more efficient to increase the number of topological nodes between HFs and NFs (X1 nodes) than to increase the number of topological nodes among NFs (X2 nodes) to enhance the production of the horizontal well. Moreover, the horizontal well with tree topology is more likely to obtain higher production compared with other fracture topologies during the middle-late flow period. In addition, field pressure analysis suggests that the number of X1 nodes and the condition of the bottom-hole pressure can determine the pressure drop around the horizontal well while the shape of the pressure-disturbed zone of the MFHW is mainly determined by the number of X2 nodes and the fracture topological type.