bluuebunny/crossref_metadata_2025 huggingface dataset:
A fast CU partition algorithm of ERP 360‐degree video based on deep learning
Authors: Xiang Hai , Chen Fen , Peng Zongju , Huang Lian
Published: January 2025

This article proposes a deep‐learning‐based fast coding unit (CU) partition algorithm to reduce encoding time of equirectangular projection (ERP) 360‐degree videos in versatile video coding. First, an ERP 360‐degree dataset with ERP latitude characteristics and quantitative parameter characteristics is established. Then, a lightweight prediction partition convolutional neural network is designed to predict the partition probability of 44 CU edges in 3232 luminance CU. Finally, an intra prediction decision‐making scheme is developed to reduce the number of candidate modes of CUs with size equal to or smaller than 3232, thereby achieving fast encoding. Experimental results show that the proposed method saves 58.51% of encoding time in All Intra configuration and only increases Bjontegaard delta bit‐rate by 1.39%.
Binary and grouped open clusters: A new catalogue
Authors: Palma T. , Coenda V. , Baume G. , Feinstein C.
Published: January 2025

Context. Understanding the formation and evolution of star clusters in the Milky Way requires precise identification of clusters that form binary or multiple systems. Such systems offer valuable insight into the dynamical processes and interactions that influence cluster evolution.

Aims. This study aims to detect and classify star clusters in the Milky Way that are part of double or multiple systems. Specifically, we seek to detect clusters that form gravitationally bound pairs or groups of clusters and distinguish between different types of interactions based on their physical properties and spatial distributions.

Methods. We used an extensive star cluster database which includes 7167 clusters. By estimating the tidal forces acting on each cluster through the tidal factor and considering only close neighbours (within 50 pc), we identified a total of 2170 star clusters forming part of double or multiple systems. Pairs were classified as binaries, capture pairs, or optical pairs based on proper motion distributions, cluster ages, and colour-magnitude diagrams.

Results. Our analysis identified 617 paired systems, and they were successfully classified using our scheme. Additionally, we found 261 groups of star clusters with three or more members, providing further evidence of the presence of multiple systems within the Milky Way that exhibit significant tidal interactions.

Conclusions. The method we present provides an improved approach for identifying star clusters that share the same spatial volume and experience notable tidal interactions.
Effective and Catalyst-Free Preparation of Thiazolidines via Novel [3+2] Annulation of 1,4-Dithiane-2,5-diol and Benzothiazolimines
Authors: Song Xiang-jia , Lu Jin-rong , Liu Min , Zhao Lin-quan , Cui Wen-quan
Published: January 2025

A novel [3+2] annulation of 1,4-dithiane-2,5-diol and benzothiazolimines has been developed for the efficient, one-step preparation of highly sterically demanding thiazolidines in excellent yields (up to 99%) and moderate diastereoselectivities (1:1 to 2.4:1) under mild conditions within a few minutes. A series of thiazolidines compounds were obtained and a scaled-up experiment was conducted with excellent results. The absorption, metabolism, and toxic (ADMET) properties of the compounds were evaluated with good results, demonstrating the potential applications of this protocol.
Feasibility of proton–boron fusion under non-thermonuclear steady-state conditions: Rider's constraint revisited
Authors: Liu Shujun , Wu Dong , Liu Bing , Peng Yueng-Kay Martin , Dong Jiaqi , Liang Tianyi , Huang Hairong , Sheng Zheng-Mao
Published: January 2025

T. H. Rider investigated the challenges of sustaining p-11B fusion away from ThermoNuclear Steady-State accounting for Bremsstrahlung losses (TNSSB) in his 1997 paper [Phys. Plasmas 4, 1039 (1997)]. We revisit part of his work using first-principles particle simulations, which more accurately capture the underlying physical processes. This study supports the aspects of Rider's analysis by considering non-Maxwellian electron velocity distributions and significantly lowering electron temperatures compared to ion temperatures. Under these conditions, the minimum recirculating power needed to sustain a non-TNSSB state remains much higher than the fusion power output. However, by using updated fusion cross section data and expanding Rider's parameter space to include higher electron temperatures, we find a net energy gain window. This is consistent with findings by Putvinski et al. [Nucl. Fusion 59, 076018 (2019)]. Higher electron temperatures increase Bremsstrahlung radiation losses but reduce electron-ion energy transfer. For non-TNSSB p-11B fusion plasmas, as the system approaches a TNSSB state, achieving net energy gain requires lower energy conversion efficiencies. Near ignition conditions (Qfuel≥10) are found when ion temperatures (Ti) range from 200 to 600 keV in a TNSSB. At these conditions, an optimal electron-to-ion temperature ratio (Te/Ti) between 0.4 and 0.6 minimizes the required product of plasma density and confinement time, provided Bremsstrahlung losses are offset by electron-ion interaction power. Reducing Te/Ti below this range for a given Ti increases the required recirculating power and reduces the achievable Q. Finally, deviations from Maxwellian velocity distributions for electrons and ions may offer additional pathways toward achieving ignition.
X-point effects on the ideal MHD modes in tokamaks in the description of dual-poloidal-region safety factor
Authors: Zheng Linjin , Kotschenreuther M. T. , Waelbroeck F. L. , Austin M. E.
Published: January 2025

The flux coordinates with dual-region safety factor (q) in the poloidal direction are developed in this work. The X-point effects on the ideal MHD modes in tokamaks are then analyzed using this coordinate system. Since the X-point effects mainly affect the edge region, the modes localized at the tokamak edge are particularly examined. Two types of modes are studied. The first is related to the conventional peeling or peeling-ballooning modes. The mode existence aligned with the local magnetic field in the poloidally core region as observed experimentally is confirmed. The X points are shown to contribute to a stabilizing effect for the conventionally treated modes with the surface-averaged q and with the tokamak edge portion truncated. The other is the axisymmetric modes localized in the vicinity of X points, which can affect the cross-field-line transport near the X points. The existence of axisymmetric modes points to the possibility of applying a toroidally axisymmetric resonant magnetic perturbation (RMP) in the X-point area for mitigating the edge localized modes, which can be an alternative to the current RMP design. The dual q description also has important implications for the existing non-axisymmetric RMP concept. It helps to understand why the RMP suppression of edge localized modes is difficult to achieve in the double-null tokamak configurations and points to the possibility of further improving the current RMP concept by considering the alignment to the local q.
Structural and electrical properties of fiber textured and epitaxial molybdenum thin films prepared by magnetron sputter epitaxy
Authors: Sundarapandian Balasubramanian , Raghuwanshi Mohit , Straňák Patrik , Yu Yuan , Lyu Haiyan , Prescher Mario , Kirste Lutz , Ambacher Oliver
Published: January 2025

Molybdenum (Mo) due to its optimal structural, physical, and acoustic properties finds application as electrode material in aluminum scandium nitride and aluminum nitride (AlN) based bulk acoustic wave (BAW) resonators. Epitaxial Mo thin films exhibiting low resistivity can improve the performance of the BAW resonator by enhancing both the electro-mechanical coupling coefficient (keff2) and quality factor Q. In this study, we systematically vary the growth temperature of Mo grown on fiber-textured and epitaxial wurtzite-aluminum nitride (AlN) to study the changes in structural and electrical properties of the Mo films. Results show that Mo grown at 700 °C on epitaxial AlN exhibits low surface roughness (Rq = 0.8 nm), large average grain diameter (dgrain = 330 nm), low resistivity (ρ=6.6 ± 0.06  μΩ cm), and high crystal quality (XRD Mo 110 ω-FWHM = 0.63°). XRD pole figure and ϕ-scan analysis reveal that irrespective of the growth temperature, Mo is fiber textured on fiber-textured AlN and has three rotational domains on epitaxial AlN. This study shows that the resistivity of Mo reduces with increasing growth temperature, which we relate to increasing average grain diameter. Additionally, we show that fiber-textured Mo has more high angle grain boundaries resulting in consistently higher resistivity than its epitaxial equivalent.
A circuit simulation model for resistive random-access memory devices based on CsBi3I10 perovskite thin films
Authors: Dai Guoshu , Lu Haodong , Chen Xiaomei , Rong Zeren , Huang Huiyan , Zhu Guanyao , Liu Zhen
Published: January 2025

This article proposes a circuit simulation model that can simulate the electrical behaviors of resistive random-access memory (RRAM) devices based on CsBi3I10 perovskite active layer. The CsBi3I10 perovskite thin films were fabricated using a sol-gel method and the structural properties were obtained with x-ray diffraction and scanning electron microscope analysis. The resistive switching memory behaviors of the RRAM devices were studied, showing that the resistance states can be well maintained for a duration of 104 s as well as in 2500 repeated Set/Reset operations during electrical measurements. To simulate the resistive switching behavior, a circuit simulation model was developed. The simulation results yielded good fitting to the experimental results, suggesting promising applications of the proposed model in this work for various kinds of RRAM devices.
Modulating single molecular electron sources with light: Opportunities and challenges
Authors: Yanagisawa Hirofumi
Published: January 2025

Applying a strong, constant electric field at single-C60 molecule protrusions formed on a metallic substrate can cause electrons to be emitted from individual single molecules into a vacuum. The shapes of such single molecular electron sources reflect the shapes of the molecular orbitals from which the electrons originate. By illuminating the source with light pulses, photo-excited electrons can be emitted from different molecular orbitals, thereby modulating the electron sources at a subnanometric scale. In this context, we discuss the opportunities presented by this light-induced modulation of electron emission for developing a unique scheme to integrate ultrafast switches into a single molecule and for advancing high-resolution, ultrafast electron microscopy. We also discuss the experimental and theoretical challenges associated with this approach, such as the requirements for picoscale stability and controllability of molecular positions, as well as the need for large-scale ab initio calculations under strong constant fields.
Synaptic transistor based on reversible hydrogenation of graphene channel
Authors: Hu Yiqian , Huang Lei , Chang Quanhong , Peng Xun , Hu Gujin , Shi Wangzhou
Published: January 2025

Graphene transistors with a gate-controlled transition of neuromorphic functions between artificial neurons and synapses have attracted increasing attention because the atomic thickness could be easily modulated by different stimuli, which is very beneficial for synaptic applications. As a modulation method, a graphene electrolyte-gated transistor (EGT) has been proposed, in which the electrical conductance of the graphene channel is modulated by reversible electrochemical hydrogenation of graphene. However, only a sparse physically realized graphene-based synaptic H+-EGTs have been reported due to the difficulty of achieving a high concentration of protons at the electrolyte–graphene interface. Here, we have reported the H+-EGTs with a highly defective graphene channel and a gel electrolyte [H3PO4/poly(vinyl alcohol)], which is based on hydrogenation and dehydrogenation of highly defected-graphene, performing the similar functions as the common artificial synaptic transistors, with good retention (<1% attenuation per minute), analog tunability (>200 nonvolatile states), and precisely controllable resistance (∼0.4% step flipped per synaptic event). In addition, the cyclic voltammetry test was applied to confirm the hydrogenation and dehydrogenation of the graphene channel. It is expected that this principle can provide ideas for designing graphene-based artificial synapses enabling integrated functions of in-memory computing and in-memory sensing for the neuromorphic system.
Cryogenic front-end circuit for capacitive sensing in superconducting gravimeters
Authors: Li Yaqiong , Liu Lu , Chen Yaqin , Zhang Ning , Chen Liang , Liu Xiangdong
Published: January 2025

Capacitive sensors are commonly used in superconducting gravimeters due to their high resolution and low drift. This study developed a cryogenic front-end circuit for superconducting gravimeters to reduce the negative effects of parasitic capacitance on capacitive sensors. The front-end circuit comprises a noiseless superconducting transformer and a low-noise cryogenic preamplifier, both of which are positioned adjacent to the capacitive sensor probe. Compared with the front-end circuit operating at 300 K, the transfer coefficient of the front-end circuit increases from 131 to 1070 V/m, and the equivalent displacement noise reduces from 1.4 × 10−10 to 5.0 × 10−11 m/Hz1/2 within a frequency band from 10−3 to 1 Hz. The temperature coefficient of the cryogenic preamplifier is 0.3%/K, and the superconducting transformer’s matching factor has adjusted as low as (2.4 ± 0.2) × 10−4. The cryogenic front-end circuit was finally applied to a superconducting gravimeter. The observed gravity data satisfactorily fit the theoretical tidal model, implying good long-term stability for the developed front-end circuit.
Voltage controlled light states in a spatially pseudo-random bit sequence encoded optical lattice
Authors: Dey Suman , Das Nikhil Ranjan
Published: January 2025

We have demonstrated reconfigurable light states in an optical lattice utilizing the electro-optic Pockels effect in a LiNbO3 slab through altering the transverse refractive index profile of the lattice by pseudo-random bit sequence (PRBS). By modifying the PRBS equivalent voltage range, different light states (ballistic, superdiffusive, diffusive, subdiffusive, and localized) are achieved within the completely disordered lattice. Furthermore, altering the maximum length size and number of periods of the PRBS creates lattices with different pseudo-random refractive index patterns. This provides a broader range of voltage control for switching from superdiffusive state to diffusive state than completely disorder lattice, allowing for precise voltage control over spatial profile for specific applications. This reconfigurable light states in this PRBS controlled lattice hold significant promise for various uses within a single integrated platform even after fabrication.
Dimensional confinement and superdiffusive rotational motion of uniaxial colloids in the presence of cylindrical obstacles
Authors: Varma Vikki Anand , Babu Sujin B.
Published: January 2025

In biological systems such as cells, the macromolecules, which are anisotropic particles, diffuse in a crowded medium. In the present work, we have studied the diffusion of spheroidal particles diffusing between cylindrical obstacles by varying the density of the obstacles as well as the spheroidal particles. Analytical calculation of the free energy showed that the orientational vector of a single oblate particle will be aligned perpendicular, and a prolate particle will be aligned parallel to the symmetry axis of the cylindrical obstacles in equilibrium. The nematic transition of the system with and without obstacles remained the same, but in the case of obstacles, the nematic vector of the spheroid system always remained parallel to the cylindrical axis. The component of the translational diffusion coefficient of the spheroidal particle perpendicular to the axis of the cylinder is calculated for the isotropic system, which agrees with analytical calculation. When the cylinders overlap such that the spheroidal particles can only diffuse along the direction parallel to the axis of the cylinder, we can observe dimensional confinement. This was observed by the discontinuous fall of the diffusion coefficient, when plotted against the chemical potential both for a single particle and for a finite volume fraction. The rotational diffusion coefficient quickly reached the bulk value as the distance between the obstacles increased in the isotropic phase. In the nematic phase, the rotational motion of the spheroid should be arrested. We observed that even though the entire system remained in the nematic phase, the oblate particle close to the cylinder underwent a flipping motion. The consequence is that when the rotational mean squared displacement was calculated, it showed a super-diffusive behavior even though the orientational self-correlation function never relaxed to zero, showing this to be a very local effect.
Accurate DFT simulation of complex functional materials: Synergistic enhancements achieved by SCAN meta-GGA
Authors: Ke Da , Sun Jianwei , Zhang Yubo
Published: January 2025

Complex functional materials are characterized by intricate and competing bond orders, making them an excellent platform for evaluating the newly developed strongly constrained and appropriately normed (SCAN) density functional. In this study, we explore the effectiveness of SCAN in simulating the electronic properties of displacive ferroelectrics (BaTiO3 and PbTiO3) and magnetoelectric multiferroics (BiFeO3 and YMnO3), which encompass a broad spectrum of bonding characteristics. Due to a significant reduction in self-interaction error, SCAN manifests its improvements over the Perdew–Burke–Ernzerhof (PBE) method in three aspects: SCAN predicts more accurate ionicity, produces more compact orbitals, and better captures d-orbital anisotropy. Particularly, these synergistic enhancements lead to notable phenomena in calculating the bandgap of YMnO3: while the PBE+U simulation may suggest a strong correlation appearance attributed to high Hubbard-like U values (∼5 eV), the value is dramatically lower (∼1 eV) in the SCAN+U method. Furthermore, we provide an intuitive analysis of SCAN’s operational principles by examining the complex electron densities involved. These insights are theoretically intriguing and have practical implications, potentially encouraging wider adoption of SCAN in the computational modeling of complex functional materials.
Overlap-scanning self-referencing diffractive imaging with enlarged field of view under incoherent illumination
Authors: Sun Hairui , Wang Zhuoyi , Ouyang Yiqin , Zhang Hao , Lu Xingyuan , Cai Yangjian , Zhao Chengliang
Published: January 2025

Coherent diffractive imaging (CDI), especially the ptychography, has been widely used in quantitative phase imaging. However, in traditional diffractive imaging schemes, a highly coherent light source is required for a better-posed inverse problem. Considering that the high coherence cannot be guaranteed in all cases and to avoid the multi-mode of low-coherence light sources complicating the iterative modeling of diffractive imaging, we proposed an overlap-scanning self-referencing diffractive imaging. As a non-iterative partially coherent diffractive imaging method, self-referencing diffractive imaging was combined with the procedure of overlap-scanning ptychography. It does not require prior knowledge of light source coherence, and only a coherent inverse problem was needed to be solved in the final stitching. It has been demonstrated to be able to recover the complex amplitude of objects illuminated by various low-coherence light sources. This study presents significant potential for applications in phase imaging with a wide-field of view under incoherent illuminations.
Bee-yond the plateau: Training QNNs with swarm algorithms
Authors: Guerrero Rubén Darío
Published: January 2025

In the quest to harness the power of quantum computing, training quantum neural networks (QNNs) presents a formidable challenge. This study introduces an innovative approach, integrating the Bees Optimization Algorithm (BOA) to overcome one of the most significant hurdles—barren plateaus. Our experiments across varying qubit counts and circuit depths demonstrate the BOA’s superior performance compared to the Adam algorithm. Notably, BOA achieves faster convergence, higher accuracy, and greater computational efficiency. This study confirms BOA’s potential to enhance the applicability of QNNs in complex quantum computations.
Effective demagnetizing tensor incorporating finite width effect for magnetic nanowire design in racetrack devices
Authors: Shirokura Takanori
Published: January 2025

Structural engineering is a promising approach to enhance the performance of racetrack devices in term of power consumption for domain wall dynamics and shift errors via the control of the in-plane shape anisotropy in magnetic nanowires. Because the in-plane shape anisotropy is determined by the nanowire width, it is essential to incorporate the width effect into the demagnetizing tensor to design racetrack devices through a structural approach; however, a quantitative evaluation of the width effect on the demagnetizing tensor is still lacking. In this work, we have derived the formula for the effective demagnetizing tensor in nanowires with finite width. We also analytically revealed that the special width, at which intrinsic pining potential vanishes, is proportional to the domain wall width. The derived formulas were in good agreement with the two-dimensional micromagnetic simulation results at various nanowire widths, demonstrating their validity. Our results provide a guideline for designing racetrack devices with low power consumption and minimal shift errors via structural engineering.
Magic-NOVEL: Suppressing electron–electron coupling effects in pulsed DNP
Authors: Javed Amaria , Ghazi Marwa Yaser , SubbaRao Redrouthu Venkata , Equbal Asif
Published: January 2025

Pulsed dynamic nuclear polarization (DNP) enhances the nuclear magnetic resonance sensitivity by coherently transferring electron spin polarization to dipolar coupled nuclear spins. Recently, many new pulsed DNP techniques such as NOVEL, TOP, XiX, TPPM, and BEAM have been introduced. Despite significant progress, numerous challenges remain unsolved. The electron–electron (e–e) interactions in these sequences can severely disrupt the efficiency of electron–nuclear (e–n) polarization transfer. In order to tackle this issue, we propose the magic-NOVEL DNP method, utilizing Lee–Goldburg decoupling to counteract e–e coupling effects. Our theoretical analysis and quantum mechanical simulations reveal that magic-NOVEL significantly improves the transfer efficiency of DNP, even at shorter e–e distances. This method offers a new perspective for advancing pulsed DNP techniques in systems with dense electron spin baths. Furthermore, we demonstrate the effectiveness of phase-modulated Lee–Goldburg sequences in improving pulsed DNP transfer.
The theory of Barlow packings: Basic properties and cohesive energies from exact lattice summations within the sticky hard-sphere model
Authors: Cooper Shaun , Robles-Navarro Andres , Smits Odile R. , Schwerdtfeger Peter
Published: January 2025

The theory of periodic Barlow multi-lattices (X1X2…XN)∞ with Xi ∈ {A, B, C} and Xi ≠ Xi+1 of stacked two-dimensional hexagonal close-packed layers is presented and used to derive exact lattice sum expressions in terms of fast converging Bessel function expansions for inverse power potentials. We describe in detail the mathematical properties of Barlow sphere packings and demonstrate that only two basic lattice sums are required to describe all periodic packings. For the sticky hard-sphere model with an attractive inverse power law potential, we find a linear correlation between the cohesive energies of different Barlow packings and the face-centered cubic packing fraction. We introduce an efficient algorithm for enumerating the unique periodic Barlow sequences for any given period N. The theory and lattice sums introduced here pave the way for the future treatment of Barlow multi-lattices.
A bionic microdroplet array chip for particle trapping
Authors: Du Lin , Ma Lili , Zhou Zijian , Huang Long , Luo Bokai , Zhou Jia , Jing Dalei
Published: January 2025

High-efficiency particle trapping in microdroplet array has wide applications in fields such as biomedical and chemical engineering. Using a closed microdroplet array chip, consisting of a top hydrophobic surface and a bottom bioinspired hydrophilic micropore array with rounded sidewalls, the droplet generation mechanism within the bionic chip is numerically and experimentally studied. During the contact between the liquid surface and the micropore, the rounded sidewalls facilitate the rupture of the liquid interface, enhancing the stability of the droplet array generated within the micropore array. By analyzing the quasi-static process when liquid enters the micropores, a void-free perfusion model is established to analyze the effects of parameters of the micropore, such as micropore size and contact angle, on the perfusion efficiency of liquid within the micropore. The particle trapping experiments confirm that particles can be effectively captured within the microdroplet array. The present work is expected to provide useful insights for enhancing the stability of the microdroplet array for high-efficiency particle trapping.
Coupling of photoluminescence and flexoelectricity in all-inorganic flexible transparent heterojunctions induced by mechanical strain
Authors: Yang Tinghong , Gu Hao , Zhang Xinyan , Chen Mengli , Li Zishuo , Liu Baoming , Chen Hongqing , Chen Deyang , Sun Hailing
Published: January 2025

Flexible and transparent optoelectronic technology has shown great application prospects in various fields. Introducing rare earth luminescent centers into inorganic ferroelectric systems can benefit the electrical properties by utilizing the polar nanodomains brought about by rare earth doping and also facilitate the investigation of coupling effect between luminescence modulation and flexoelectric effect. This article studies Pr3+-doped barium titanate all-inorganic flexible transparent heterojunctions and explores the direct modulation of the fluorescence and flexoelectric response through mechanical strain stimulation. We aim to investigate the essential correlation and physical mechanism of strain-flexoelectricity-photoluminescence (force-electric-photon) coupling, providing an important basis for the dynamic balance regulation between radiative and non-radiative transitions. Therefore, this work will significantly promote the development of highly integrated flexible sensing and intelligent optoelectronic devices.
Out-of-phase ELDOR spectroscopy: A precise tool for investigating structure and dynamics of charge-transfer states in organic photovoltaic blends
Authors: Popov Alexander A. , Lukina Ekaterina A. , Reijerse Edward J. , Lubitz Wolfgang , Kulik Leonid V.
Published: January 2025

We developed a technique allowing the direct observation of photoinduced charge-transfer states (CTSs)—the weakly coupled electron–hole pairs preceding the completely separated charges in organic photovoltaic (OPV) blends. Quadrature detection of the electron spin echo (ESE) signal enables the observation of an out-of-phase ESE signal of CTS. The out-of-phase Electron–Electron Double Resonance (ELDOR) allows measuring electron–hole distance distributions within CTS and its temporal evolution in the microsecond range. The technique was applied to OPV bulk heterojunction blends of different donor polymers, including the benchmark polymer P3HT and the high-performance polymer PCDTBT, with the fullerene PC61BM acceptor. The corresponding electron–hole distance distributions were obtained using the Tikhonov regularization. It was found that not only the dipolar interaction but also the exchange interaction contributes to the formation of the out-of-phase ELDOR signal. By varying the delay time after photoexcitation, we observed CTSs at different stages of charge separation. The initial distribution of the electron–hole distances for different blends correlates with their photoelectric conversion efficiency, with shorter average thermalization distances found for the blends of PC61BM with the less efficient regiorandom polymer P3HT. Spin-selective recombination of the CTS was unambiguously demonstrated for the blend of regioregular P3HT with PC61BM. It produces characteristic features in the out-of-phase ELDOR trace for small “dipolar” evolution times. These data allow us to estimate the CTS recombination rate for a certain distance between the electron and the hole within the CTS. The proposed method can be used to probe CTS in a variety of OPV active layer materials.
Elastic properties associated with liquid–liquid phase transition in molten cerium
Authors: Xu Liang , Li Xuhai , He Qiang , Yang Jing , Sun Shouli , Li Jun , Hu Jianbo , Wu Qiang
Published: January 2025

Cerium is regarded as one of the few metals that exhibit a first-order liquid–liquid phase transition (LLPT). However, despite the theoretical attribution of the LLPT to the localized-itinerant transition of f-electrons, there is still a lack of compelling experimental evidence to support this important scientific inquiry. In this study, we investigate the evolution of sound velocity in molten cerium along the isothermal and isobaric paths under static compression. Drawing parallels with the extensively studied γ–α isostructural phase transition, the V-shaped trend of temperature-dependent sound velocity in liquid suggests the existence of LLPT and identifies an associated mechanism predominating liquids' compressibility.
Unipolar fields produced by ultrafast optical gating of terahertz pulses
Authors: Gorelov S. D. , Novokovskaya A. L. , Bodrov S. B. , Sarafanova M. V. , Bakunov M. I.
Published: January 2025

Unipolar (sub-cycle) electromagnetic fields are a subject of current interest as a possible useful tool for light–matter interaction studies and applications. We propose, numerically simulate, and experimentally prove a method to produce unipolar terahertz fields by optical gating of conventional bipolar terahertz pulses in a GaAs wafer. In particular, picosecond long unipolar pulses with the electric field strength of ∼1 kV/cm were detected by electro-optic sampling at the output of the wafer.
Loss of structural specificity in 3D genome organization upon viral infection is predicted by polymer physics
Authors: Fontana Andrea , Bianco Simona , Tafuri Fabrizio , Esposito Andrea , Abraham Alex , Conte Mattia , Vercellone Francesca , Di Pierno Florinda , Kundu Sumanta , Guha Sougata , Di Carluccio Ciro , Prisco Antonella , Nicodemi Mario , Chiariello Andrea M.
Published: January 2025

In the last years, it has been proved that some viruses are able to re-structure chromatin organization and alter the epigenomic landscape of the host genome. In addition, they are able to affect the physical mechanisms shaping chromatin 3D structure, with a consequent impact on gene activity. Here, we investigate with polymer physics genome re-organization of the host genome upon SARS-CoV-2 viral infection and how it can impact structural variability within the population of single-cell chromatin configurations. Using published Hi-C data and molecular dynamics simulations, we build ensembles of 3D configurations representing single-cell chromatin conformations in control and SARS-CoV-2 infected conditions. We focus on genomic length scales of TADs and consider, as a case study, models of real loci containing DDX58 and IL6 genes, belonging, respectively, to the antiviral interferon response and pro-inflammatory genes. Clustering analysis applied to the ensemble of polymer configurations reveals a generally increased variability and a more heterogeneous population of 3D structures in infected conditions. This points toward a scenario in which viral infection leads to a loss of chromatin structural specificity with, likely, a consequent impact on the correct regulation of host cell genes.
Hydrogen bonding blues: Vibrational spectroscopy of the TIP3P water model
Authors: Piskulich Zeke A. , Cui Qiang
Published: January 2025

The computational spectroscopy of water has proven to be a powerful tool for probing the structure and dynamics of chemical systems and for providing atomistic insight into experimental vibrational spectroscopic results. However, such calculations have been limited for biochemical systems due to the lack of empirical vibrational frequency maps for the TIP3P water model, which is used in many popular biomolecular force fields. Here, we develop an empirical map for the TIP3P model and evaluate its efficacy for reproducing the experimental vibrational spectroscopy of water. We observe that the calculated infrared and Raman spectra are blueshifted and narrowed compared to the experimental spectra. Further analysis finds that the blueshift originates from a shifted distribution of frequencies, rather than other dynamical effects, suggesting that the TIP3P model forms a significantly different electrostatic environment than other three-point water models. This is explored further by examining the two-dimensional infrared spectra, which demonstrates that the blueshift is significant for the first two vibrational transitions. Similarly, spectral diffusion timescales, evaluated through both the center line slope and the frequency–frequency time correlation function demonstrate that TIP3P exhibits significantly faster spectral dynamics than other three-point models. Finally, sum-frequency generation spectroscopy calculations suggest that despite these challenges, the TIP3P empirical map can provide phenomenological, qualitative, insight into the behavior of water at the air–water and lipid–water interfaces. As these interfaces are models for hydrophobic and hydrophilic environments observed in biochemical systems, the presently developed empirical map will be useful for future studies of biochemical systems.
Effects of wings number on the flight performance of autorotating seeds
Authors: Liu Chenxi , Zeng Lifang , Li Jun , Shao Xueming
Published: January 2025

Some natural wind-borne plants spread their seeds in a mode of autorotation, for example, maple, pterocarya stenoptera, and tristellateia. However, these wind-borne seeds have different numbers of wings. The current work focuses on the effects of wings number on the flight performance of autorotating seeds. Experiment and numerical simulation are used to analyze the aerodynamic performance of tristellateia seeds with different numbers of wings. In the free fall experiments, it is found that reducing the wings number leads to larger wing loadings, larger stable descending velocities, and larger spinning rates. The growth rate of descending velocity and spinning rate are related to the wings number. However, as the number of clipped wings increases, the seeds are more likely to fall into unsteady rotation even free fall. Numerical simulations are used to analyze the flow field around the rotating tristellateia seeds. It finds that seeds with clipped wings have larger pressure difference between the upper and lower wing surfaces, which contributes to larger lift. Three kinds of vortex systems occur on the rotating seeds: the leading-edge vortex, the wing tip vortex, and the separated vortex. Seeds with different clipped wings present various vortex morphology and structure. A stable separated vortex ring dominates the stable autorotation of tristellateia seeds. However, an unstable separated vortex emerges on the seeds with less wings, which makes these seeds difficult to achieve stability.
Influence of dielectric characteristics on bubble dynamics and material removal mechanism in electrical discharge machining
Authors: Peng Weiye , Tang Jiajing , Li Zhengkai , Yin Mulong , Qiu Zhiwei
Published: January 2025

The bubble formation process during electrical discharge machining (EDM) is affected by the dielectric and the magnitude of the flow rate. At present, the bubble dynamic characteristics during material removal are insufficiently characterized in existing studies. In this study, the bubble formation processes of the workpiece and the dielectric were simulated based on the model of dielectric flushing three-phase flow for EDM with different dielectrics and flow rates, and the bubble pressure, bubble characteristics, and material removal mechanism were analyzed. Meanwhile, the flow rate experiments with single pulse discharge in de-ionized water and dielectric flushing experiments were carried out to verify the material removal mechanism in the above EDM in liquid. These results showed that both the debris accumulation and the dielectric flushing effect can delay the bubble explosion by impacting bubble pressure. The degree of bubble expansion and the volume of molten fluid determine the size of the molten region together. The weakening of the impact effect of the molten fluid promotes stable bubble growth while decreasing the bubble growth rate. The material removal contribution of the dielectric bubble is higher than that of the workpiece bubble, 80% of the molten material is discharged through the dielectric bubble by enhancing the dielectric flushing. There are more frequent evolution behaviors of bubble dynamics in de-ionized water and emulsion in a growth period than in kerosene. The study of these bubble behaviors revealed a more detailed understanding of the three-phase flow system in EDM, providing a foundation for the improvement of both EDM efficiency and material quality.
Temperature-independent zero–zero-birefringence polymer using N-substituted maleimide and styrene
Authors: Hotta Hikaru , Koike Yasuhiro
Published: January 2025

To date, the orientational birefringence and the photoelastic birefringence of alternating copolymers have not been studied in detail. We focused on N-substituted maleimide (RMI) and styrene (St) as alternating copolymers and analyzed the birefringence, refractive index, and glass transition temperature (Tg) of the alternating copolymers. It was found that the photoelastic coefficient and Tg exhibit a nonlinear relationship with the composition ratio of RMI and St. It is considered that the alternating copolymerization of RMI and St confirms that the conformation is inhibited by interacting with each other. A zero–zero-birefringence polymer that exhibits no birefringence was obtained by using N-ethylmaleimide and St and adjusting the composition ratio. This polymer showed a high Tg, low haze, and a low temperature dependence of birefringence.
Near-wall flow characteristics around longitudinal ribs in fully developed turbulent channel flows
Authors: Kushwaha Ranjan , Sarkar S. , Biswas Gautam
Published: January 2025

This study deploys Large Eddy Simulations of turbulence to investigate secondary flows and near-wall turbulence characteristics induced by surface-mounted longitudinal ribs in a channel flow. The systematic variation of the Reynolds number (Reτ, based on friction velocity and channel height) between 300 and 950 and the rib aspect ratio (W/h, W and h represent the width and height of the rib, respectively) between 1 and 3 are considered, where the rib height h of 0.1H (H is the channel height) and rib spacing of 8h are held constant. The near-wall flow physics are also examined across varying Reynolds numbers while maintaining a constant inner-scaled rib geometry. The impact of the roughness function is evaluated in relation to the strength of the near-wall secondary flow. Additionally, the effects of increasing Reτ on the variations of extrinsically averaged Reynolds stresses in the wall-normal direction are analyzed. Some of the Reynolds stress contours show a correlation with the vortex cores on the secondary flow plane. The presence of ribs does not significantly influence the average streak spacing near the wall. The production and dissipation rates of turbulent kinetic energy (TKE) remain nearly constant above y/H=0.4 (y is the wall-normal direction) irrespective of the value of Reτ and the rib aspect ratio. The numerical flow visualization and TKE budget analysis reveal that secondary vortices primarily form near the ribs. The TKE budget also shows that the narrow production zone is balanced by dissipation at low Reτ, expanding significantly at high Reτ.
Study on the diffusion mechanism of columnar-hemispherical infiltration grouting form of quick-setting slurry considering spatial and temporal variations of slurry viscosity
Authors: Zhu Guangxuan , Guo Shaoxuan , Shi Jinjiang , Zhang Qingsong
Published: January 2025

The time-varying viscosity of quick-setting slurries will cause the spatial variation of slurry viscosity, which has an important impact on the diffusion mechanism of infiltration grouting. With the time-varying Bingham fluid constitutive model and the uniform capillary group theory, a cylindrical–hemispherical slurry infiltration diffusion model was established, considering the time-space variation of slurry viscosity. According to the soil parameters and slurry rheological parameters, the slurry pressure can be calculated at different diffusion radius and times. The effects of the permeability, porosity, and grouting rate of the injected medium on the grouting pressure and grouting diffusion radius were analyzed. The medium porosity is very critical for the design of the slurry diffusion radius. A 3-dimensional infiltration grouting test was carried out. The infiltration grouting pressure under different grouting rates and soil parameters were obtained. The results obtained from theoretical model were compared and verified with the test results. The results show that the grouting pressures calculated from the infiltration diffusion model proposed in this paper are in agreement with the experimental results. The grouting pressure calculated by the theoretical model is 1.05–1.25 times of the experimental value.
The turbulence evolution of tangential supersonic cooling film using direct numerical simulation
Authors: Zhao Rui , Wu Xiaoshuai , Zhao Yuxin
Published: January 2025

Supersonic film cooling is a potential approach to thermally protecting hypersonic aircraft. To unveil the turbulence evolution and inherent energy transport, a direct numerical simulation (DNS) of supersonic film cooling is performed, wherein the cooling gas with a Mach number of 2.0 is tangentially injected into a turbulent boundary layer with a Mach number of 3.0. Particular attention is paid to the evolution of turbulent structures reflected by energy spectra. The overall flow response can be described as the decay of upstream wall turbulence and the re-establishment of the downstream wall shear layer. Visualizations of vortex identification clearly show that well-shaped hairpin vortices oriented to the laminar cooling film are formed in the mixing layer. The decompositions of wall skin friction reveal that the tangential film causes considerable drag reduction downstream, and this is the joint benefit of the thickening of the wall shear layer and the decaying of upstream turbulence. The turbulent statistics reveal the coexistence of two energy peaks in the flow field. One in the mixing layer is the remnant of upstream turbulence and gradually decays, while the other near the wall is newly generated and keeps growing. The conclusion is further confirmed by energy spectra, which also show that streaky structures scaling differently from those in a turbulent boundary layer are formed near the wall. It is interesting to find that the two energy sites directly exchange turbulent kinetic energy through mean convection, and they redistribute energy toward the bracketing region through turbulent transport.
High-throughput computational screening of auxetic two-dimensional metal dichalcogenides and dihalides
Authors: Du Xue , Zhao Jinghong , Wang Jintian , Liu Xiaoqing , Ye Ziqin , Fang Liang , Zhou Miao
Published: January 2025

Auxetic materials hold tremendous potential for many advanced applications, but candidates are quite scarce, especially at two dimensions. Here, we focus on two-dimensional (2D) metal dichalcogenides and dihalides with the chemical formula MX2 by screening structures sharing the P4̄m2 space group among 330 MX2 compounds from the computational 2D materials database. Via high-throughput first-principles computations, 25 stable MX2 (M = Mg, Ca, Mn, Co, Ni, Cu, Zn, Ge, Cd, Sn; X = F, Cl, Br, I, O, S, Se) systems with in-plane negative Poisson’s ratios (NPRs) are successfully identified. Within these structures, 2D NiCl2 has the largest NPR value of −0.34, with a magnitude significantly higher than those of black phosphorene (−0.027) and SnO2 (−0.1). The distinct auxetic effect in MX2 originates from both the unique local corner-sharing tetrahedral structural motif under the low-dimensional effect and the strong orbital interaction between the d orbitals of M and the p orbitals of halogen/chalcogen atoms. As a result, Poisson’s ratio can be effectively tuned by enhancing the d–p interaction through an external biaxial strain. We reveal that these auxetic materials exhibit rich electronic and magnetic properties, covering nonmagnetic, ferromagnetic, or anti-ferromagnetic metals, semiconductors, and insulators. The extraordinary auxetic behaviors in combination with rich physical properties could lead to multifunctional nanomechanical, optoelectronic, and spintronic applications.
Mechanism of voltage frequency influence on vibration and discharge characteristics of water droplet attached to electrode
Authors: Liu Yuxin , Zhang Bo , He Jinliang
Published: January 2025

The vibration and discharge phenomena of droplets in electric fields are the focus of various applications, while the relationship between them has not been fully investigated. In this study, a synchronous platform integrating high-speed camera observation and corona current measurement was utilized to explore the influence of voltage frequency on the vibration and corona discharge characteristics of the water droplet attached to the electrode. Results show that the voltage frequency has a significant influence on the vibration and discharge characteristics of the water droplet, and a strong correlation has been observed between these two characteristics. When approaching the dynamic natural vibration range, the droplet will cause a greater water loss due to intensive vibration, resulting in a smaller stable volume and, consequently, a smaller length vibration amplitude and discharge intensity. The forced vibration model has been enhanced to explain these phenomena. The findings further advanced the theory of electro-driven control of the water droplet in vibration and corona discharge.
Effects of magnetic field and slippages on oscillating rigid spheres in magnetorheological ferrofluids
Authors: Algatheem Azza M. , El–Sapa Shreen
Published: January 2025

This study investigates the intricate dynamics of synchronized and desynchronized oscillations of rigid spheres with varying diameters immersed in magnetorheological ferrofluids. It delineates two distinct motion types: synchronized oscillation, where spheres resonate in unison due to magnetic forces, and desynchronized oscillation, characterized by out-of-phase movements stemming from disparate frequencies and hydrodynamic interactions. Employing Stokes flow theory, the research formulates a spherical solution and applies boundary conditions through a sophisticated collocation technique. Noteworthy findings indicate that drag force coefficients rapidly converge to definitive parameters, including the ratio of sphere diameters, the Hartmann number, frequency parameters, and slippage conditions, signifying independent motion at sufficient inter-sphere separations. Furthermore, the study rigorously examines the influence of variations in fluid properties and magnetic fields on sphere interactions, while also evaluating the precision of the numerical methodologies employed. The implications of this research are profound, offering significant insights for applications necessitating meticulous control over particle dynamics.