bluuebunny/crossref_metadata_2025 huggingface dataset:
Anisotropic activations controlling doublet–quartet spin conversion of linked chromophore-radical molecular qubits in fluid
Authors: Kobori Yasuhiro , Kokado Yuya , Kopp Kevin Lars , Okamoto Tsubasa , Fuki Masaaki
Published: February 2025

Light-energy conversion processes causing alternations in spin multiplicity are attracting attention, but the development of quantum sensing technology applicable to fluid environment such as inside cells has been unexploited. How to achieve efficient energy conversion with controlling spin quantum coherence in a noisy condensed system is challenging. In this study, we investigate the effect of molecular motion on electron spin polarization to control quantum information of three-spin qubits in a fluid environment by using steric effects of organic molecules at room temperature. Using time-resolved electron paramagnetic resonance to observe light-induced generation and transfer of quantum entanglement, we directly observed a photoexcited quartet state generated in a radical-chromophore coupled system and clarified details of the electron spin polarization mechanism including a decoherence effect by activation of anisotropic molecular motion by the steric effects.
Growth of crystalline thin films of picene on semimetallic Bi(111) surface
Authors: Fu Shi-Run , Yu Tao , Zhang Ting-Ting , Yang Xiao-Tian , Sun Kai , Tao Min-Long , Yang Ji- Yong , Wang Jun-Zhong
Published: February 2025

We report the scanning tunneling microscopy/spectroscopy (STM/STS) studies on structural and electronic properties of picene films grown on the semimetallic Bi(111) substrate held at different temperatures. Under room-temperature deposition, the picene molecules form a crystalline (001) monolayer with the standing-up orientation, indicating the weak molecule–substrate interaction. When deposited on the Bi(111) substrate held at 150 K, picene molecules form a bulk-like (211̄ monolayer with building blocks of picene trimers. High-resolution STM images reveal that each trimer consists of two tilted molecules and one side-on molecule. Further reducing the deposition temperature to 90 K leads to the formation of nanostripe arrays, in which the side-on molecules adopt the π–π stacking. STS measurements demonstrate that the crystalline (001) monolayer of picene exhibits a larger gap compared with picene crystals, which can be attributed to the decoupling of the upright standing molecules from the semimetallic Bi(111) substrate.
Utilizing ensemble Kalman filtering in proper orthogonal decomposition Galerkin reduced-order models for turbulent flow prediction
Authors: Xu Wei , Liu Caixi , Zhong Jianying , Mao Yuanxiang , Feng Shuo , Wang Zhijun , Wang Zhenjiang , Wang Bofu , Qiu Xiang
Published: February 2025

Developing reduced-order models for turbulent flow prediction is essential for engineering applications. This research introduces a reduced-order model based on the ensemble Kalman filter (EnKF) approach, designed to refine the ordinary differential equation constants in proper orthogonal decomposition Galerkin (POD-Galerkin) reduced-order models using time coefficient constraints. The model's predictive capability is validated with two cases: flow around a cylinder and flow around a wall-mounted hemisphere. Notably, the time coefficients of the POD-Galerkin model, updated with EnKF, showed high consistency with the original POD coefficients after several iterations, indicating enhanced prediction accuracy. The results revealed that only 17 iterations were required for the two-dimensional cylinder flow model to reduce the relative prediction error to below 1%. For the three-dimensional hemisphere flow case, the relative error was 2.03%, with the time coefficients' relative errors in various modes decreasing by one to two orders of magnitude compared to the traditional POD-Galerkin method. This approach effectively prevents divergence in low-order models over long time periods and provides a robust method for low-dimensional representation of high-fidelity flow fields.
Beam-driven electron-acoustic waves in auroral region of magnetosphere with superthermal trapped electrons
Authors: Jahangir R. , Ali S. , Eliasson B.
Published: February 2025

The propagation characteristics of nonlinear electron-acoustic (EA) waves are studied in a four-component magneto-plasma, containing inertial cold electrons, warm drifting beam electrons, trapped superthermal hot electrons, and static ions. A linear dispersion relation for EA waves is derived to analyze the impact of electron superthermality on the ω−k relation. For nonlinear analysis, a reductive perturbation formalism is adopted to solve the set of model equations in the form of a trapped Zakharov–Kuznetsov (tZK) equation. The latter is analyzed to determine the solitary structures in terms of phase portraits and exact soliton solutions showing the impact of electron trapping efficiency (γ), hot electron superthermality (κ), drifting speed, temperature and density of beam electrons, and temperature and density of cold electrons, using typical parameters from the short-duration burst of broad-band electrostatic noise emissions observed by the Viking spacecraft in the auroral region. The solitary structures propagate as positive potential pulses and become modified with superthermal trapped electrons, leading to hole (hump) in cold (hot) electron density excitations. The electric field structures of the EA waves are found to be in exact agreement with the observed solitary structures in the auroral region. It is observed that electric field strength associated with these waves decreases as the magnetic field increases. The present model can be used to understand the transport of energy and momentum between plasma particles and to comprehend magnetic reconnection region in magnetopause, where two-temperature electrons and large-amplitude parallel electrostatic waves have been reported by magnetopause multiscale observations.
Effect of fluid–shale interaction on hydraulic fracture effectiveness
Authors: Li Ning , Zou Yushi , Chen Shijing , Zhu Jian , Zhang Xiaohuan
Published: February 2025

The effectiveness of hydraulic fractures is one of the critical factors determining the production performance of shale oil wells. To investigate the influence of fluid–shale interaction during formation stimulation on the effectiveness of hydraulic fractures and shale oil production, first, a series of conductivity tests were performed on shale cores after soaking in different fluids, revealing the evolution rules of conductivity of propped fracture under different fluid-shale interaction mechanisms. Furthermore, by considering the fluid–shale interaction in the reservoir numerical simulation model, the impact of hydraulic fracture effectiveness evolution on shale oil well productivity and its differences in reservoirs with different permeability anisotropy were analyzed. The research results indicate that the softening of fracture surfaces caused by fluid-shale interaction causes fracture conductivity damage, and the longer the soaking time, the more severe the damage. Generally, the degree of damage on the fracture conductivity caused by water–shale interaction is higher than that caused by supercritical CO2 shale interaction under the same soaking time. When considering the damage of hydraulic fracture effectiveness caused by fluid–shale interaction, the production of shale oil wells is significantly reduced. For shale reservoirs with strong permeability anisotropy, the cumulative oil production loss caused by fluid–shale interaction is more severe than that with weak permeability anisotropy.
Engineering mechanical resonances of magnetoelectric transducers
Authors: Butscher Julian F. , Gather Malte C.
Published: February 2025

Magnetoelectric transducers are being investigated as a promising alternative for wireless power transfer in cases where small device size and/or low operation frequency are desired. To maximize the output power of such transducers, operation at their mechanical resonance frequency is imperative. However, a reduction in size along the direction of oscillation is intrinsically accompanied by an increase in resonance frequency. Here, we report on a computational shape optimization strategy to minimize the resonance frequency in magnetoelectric transducers by ≈38% within a set of given optimization constraints. We show that our algorithm can be used to guide the design of magnetoelectric transducers optimized to operate at different resonance frequencies and allows for consistent frequency spacing between transducers, thus enabling separately addressable devices and clustered operation. Finally, we propose four needle-shaped devices that could be used as bioimplants that impose minimal tissue damage upon direct insertion into tissue. The increase in resonance frequency associated with the needle shape is overcompensated by a frequency minimization step. Our work paves the way for computationally guided resonance frequency tuning in the field of magnetoelectric transducers.
Geometric engineering of pinning arrays in superconductor tapes for critical current density enhancement using conformal transformation
Authors: Owjifard Z. , Tavana A. , Hosseini M.
Published: February 2025

In this study, we investigate the influence of pinning forces and conformal mapping parameters on the critical current density of superconductor tapes. By applying dual conformal transformations to triangular pinning arrays, we utilize molecular dynamics techniques to simulate the dynamics of vortices in a type-II superconducting tape in simple triangular arrays of pinning centers and their conformally transformed structures. To this aim, we solve the Langevin equation for the vortices by specifying the forces acting on them. These forces include vortex–vortex interaction force, vortex pinning force, and thermal fluctuation force. Then, the corresponding critical current densities are calculated. The findings indicate that Jc is significantly improved at high magnetic fields in conformal triangular pinning arrays, while at low magnetic fields, the square lattice performs better.
Effect of active layer thickness on device performance of InSnZnO thin-film transistors grown by atomic layer deposition
Authors: Zhang Yu , Luo Binbin , Li Runzhou , Wu Xuefeng , Bai Rongxu , Sun Qingqing , Zhang David W. , Hu Shen , Ji Li
Published: February 2025

Amorphous oxide semiconductors have garnered significant attention in recent years for their potential in flat-panel displays and back-end-of-line-compatible monolithic 3D (M3D) integration applications. This study explores amorphous InSnZnO thin films deposited via plasma-enhanced atomic layer deposition (PEALD) and the development of high-performance PEALD ITZO thin-film transistors (TFTs) with different active layer thicknesses, fabricated under a low thermal budget of 200 °C. By optimizing the deposition process of binary oxides InOx, SnOx, and ZnOx, a shared temperature window of 170–180 °C was identified for ITZO thin-film deposition. The deposited ITZO films, irrespective of thickness, exhibit an amorphous phase. Moreover, a reduction in ITZO film thickness from 24 to 4.8 nm leads to an increase in the optical bandgap from 3.35 to 3.65 eV. The channel thickness significantly impacts the threshold voltage and carrier density of ITZO TFTs. Optimized ITZO TFTs with a 16 nm channel thickness demonstrate excellent electrical performance, including a threshold voltage of −0.58 V, a field-effect mobility of 29 cm2/V s, an on/off ratio exceeding 108, and a subthreshold swing of 74 mV/dec. Furthermore, the optimized ITZO TFT exhibits excellent stability under positive bias stress at 2 MV/cm, with a threshold voltage shift of 0.15 V after 3600 s. Consequently, ALD-based ITZO emerges as a promising channel material for future applications in transparent electronics and flat-panel displays.
Laser-induced thermal size effects in micro-Raman thermal conductivity measurements
Authors: Meydando Taher , Abdolhosseinzadeh Amir , Goktepe Emine , Milošević Milorad V. , Donmezer Nazli
Published: February 2025

Thermal conductivity measurements of submicrometer structures are at the core of the efficient power design of semiconductor devices. Micro-Raman spectroscopy measures thermal conductivity in a fast, nondestructive, and non-contact manner. However, the focused laser heating in micro-Raman experiments may cause drastic thermal size effects. To date, the role of such effects in the accuracy and limitations of the measurement has not been addressed. Here, we present an advanced thermal model to capture the role of material properties, laser power, and film thickness in the thermal size effects, based on the three-dimensional (3D) gray phonon Boltzmann transport equation. Recalling that laser-induced thermal size effects can lead to unexpectedly high local temperatures, even damaging the measured materials, our advanced 3D model gains particular importance for the accurate measurements of directional thermal conductivities in submicrometer structures using future high-resolution optical pump–probe techniques.
Droplet size in the breakup of a viscoelastic filament
Authors: Chen Siyu , Ashgriz Nasser
Published: February 2025

The breakup process of a viscoelastic filament is investigated for a range of fluids with different polymer concentrations and solvent viscosities. Images taken by a high-speed camera show that the filament first thins exponentially to a terminal diameter and then generates surface waves, which form drops in a cascade manner, known as beads-on-string structures. The time spent in the exponential thinning stage is proportional to the relaxation time (λr) of the fluid, and it takes about 6λr for the tested fluids to reach the terminal diameter. The Rayleigh–Plateau instability gives reasonable prediction on the wavelength of surface waves but overestimates the growth rate. The sizes of different generations of beads are proportional to the filament diameters at which they form and can be predicted by a model based on the filament thinning rate. The bead size distribution has a Gamma distribution, and increases in polymer concentration and solvent viscosity result in a more uniform bead size distribution.
Experimental study on the flow field inside soap bubble at different incident velocities
Authors: Zhao Qingkai , Yang Zhixuan , Xiao Wei , Li Ying , Choy Yat Sze
Published: February 2025

Bubbles are widely present in nature. However, previous scientific studies have primarily focused on the development of the outer contour of the bubble while neglecting the changing behavior of the internal flow field due to the difficulty in implementing experiments. This study designs a simple experimental device that can conveniently observe changes in the flow field inside the bubble while avoiding the tedious operation and high costs associated with the particle image velocimetry (PIV) system. Accordingly, this experiment investigates the development process of the flow field inside the bubble and the velocity conditions required for bubble formation for different incident velocities and Reynolds numbers. The study first examines the minimum flow velocity necessary for bubble formation. Then, under low-speed conditions, the flow inside the straw is laminar, and the flow field inside the bubble exhibits a single vortex structure. Under high-speed conditions, the flow inside the straw transitions to turbulent flow, and the flow field inside the bubble exhibits a four-vortex structure. The formation process of this four-vortex structure shows variations as the flow velocity increases. In addition, this study proposes corresponding physical models for bubble formation under low and high flow velocities and verifies the models.
Multiphoton dissociation dynamics of molecular oxygen O2 via two-photon resonant Rydberg states in the UV region
Authors: Sun Zhongfa , Scheidsbach Roy J. A. , Banerjee Agniva , Eppink André T. J. B. , Wei Yaxiong , Hua Zefeng , Yang Xinyan , Qin Zhengbo , Xu Xinsheng , Zheng Xianfeng , Farooq Zahid , Chen Zhichao , Parker David H.
Published: February 2025

The photodissociation and photoionization of O2 and the subsequent photodissociation of O2+ in the wavelength region of 200 to 240 nm are reported using resonance enhanced multiphoton ionization (REMPI) and velocity map imaging detection. A series of two-photon allowed Rydberg states with principle quantum number n = 3–11 converging to the ground electronic state of O2+X2Πg are used as doorway states to reach the region of superexcited states of O2 in the three-photon energy range of 15.8–18.6 eV. A detailed analysis of the kinetic energy release and anisotropy parameters of photofragments extracted from velocity map images reveals competition between neutral dissociation and autoionization and leads to the identification of different O+ formation channels. Moreover, the measurement of anisotropy parameters for each channel gives additional information on the symmetry of electronic states involved in the absorption process. Formation followed by the dissociation of vibrationally excited O2+ is the strongest channel over the full wavelength range studied. Ground and vibrationally excited O2+(X2Πg, a4Πu, A2Πu) are formed and dissociated to ionic products via one and two-photon processes. Neutral dissociation to form electronically excited atoms is important at the longer wavelengths studied and becomes noticeably less important at shorter wavelengths. These results agree with and expand on a previous study from our lab of O+ formation at a single (2 + 1) REMPI wavelength, and the results obtained in this study are found to complement our study of the electronically analogous counterpart S2, where most of the S+ ions arise from electronically excited S* atoms. The results of this study will also be of use in the pixel-to-velocity calibration of any velocity map imaging apparatus in the wide ultraviolet wavelength regions. Because O2 is a common reactant or product in many molecular dynamics studies, knowledge of its ionization/dissociation pathways at commonly used wavelengths should also be useful in avoiding signal overlap problems.
Direction tunable singly polarized excitons in wurtzite monolayer
Authors: Ma Zhuang , Li Jitao , Song Hongquan , Feng Yamin , Liu Weifeng , Xiong Wen , Wang Fei
Published: February 2025

The optical response with tunable direction and carrier transport are highly desirable for optoelectronic devices. Here, we find a switchable direction dependent singly polarized exciton with E∥x or E∥y mode in the wurtzite (wz) monolayer by the ferroelastic phase transition or external strain. This reversible singly polarized switching is facilitated by valence band inversion, which arises from the reordering of heavy-hole and light-hole states around the valence band maximum in the wz monolayer. Our results facilitate precise modulation of polarized optical transition in two-dimensional materials and paves the way for designing optoelectronic devices with fully controllable polarization transition.
Thermosolutal performance of a non-Newtonian Casson fluid in a curvilinear porous baffled chamber with irreversibility and various heating strategies
Authors: Hansda Samrat , Chattopadhyay Anirban , Pandit Swapan K. , Sheremet Mikhail A.
Published: February 2025

This study aims to investigate the thermosolutal performance and irreversibility behavior of a non-Newtonian Casson fluid in a curvilinear porous chamber with baffles under various heating strategies. Thermosolutal convection, driven by temperature and solute concentration gradients, plays a critical role in industrial processes such as electronic cooling, thermal storage, and heat exchangers. The novelty of this work lies in the combined use of a Casson fluid and strategically placed baffles within a curvilinear porous enclosure, alongside non-uniform sinusoidal heating applied to the lower boundary, utilizing multifrequency spatial heating profiles for the first time. The inclusion of baffles significantly enhances control over flow structures and heat transfer efficiency. This numerical analysis explores the effects of key parameters, including the Lewis number (1≤Le≤20), the Darcy number (10−4≤Da≤10−2), the Rayleigh number (104≤Ra≤106), and the Casson fluid parameter (0.1≤β≤10), as well as the amplitude, frequency, and offset temperature of the sinusoidal heating. In spite of solving the Navier–Stokes, thermal, and species transport equations using a higher-order compact scheme, the objective is to examine how these parameters influence flow behavior, heat and solute transfer, kinetic energy (K.E.), and entropy generation. The variation in the Casson fluid parameter (β) from 0.1 to 10 leads to significant enhancements in heat transfer, mass transfer, and kinetic energy by 44.01%, 43.85%, and 210.75%, respectively, while simultaneously reducing the total entropy generation by 4.92%.
Resonance-enhanced multiphoton ionization detection of vibrationally excited O2
Authors: Kallos Itai S. , Benfreha Kerim , Golibrzuch Kai , Zhao Hao , Bar Ilana , Schäfer Tim , Rahinov Igor , Wodtke Alec M. , Baraban Joshua H.
Published: February 2025

We report a rotationally resolved spectroscopic detection scheme for vibrationally excited molecular oxygen with high sensitivity. Two-color (2 + 1′) resonance-enhanced multiphoton ionization (REMPI) spectra of O2 hot bands were recorded for the first time via the 3dπ(v′=0)←X3Σg− (v″ = 1) Rydberg transitions. Spectroscopic constants and relative Franck–Condon factors were extracted and compared to simulations. This new access to quantum-state-resolved diagnostics of vibrationally excited O2 promises to shed light on the physical and chemical dynamics of many processes.
Two-phase flow characteristics inside a serpentine inlet in heavy rain
Authors: Wu Z. L. , Shi Z. Y. , Sun S. , Tan H. J.
Published: February 2025

Rain is a common atmospheric phenomenon encountered by aircraft and is one major cause of several catastrophic flight accidents. Stealth aircraft usually adopt the knapsack serpentine inlet layout, of which the entrance is beveled and upward, thus easily subject to external environmental effects like rain. This study investigates the effects of rain on the aerodynamic performance of a serpentine inlet by an Eulerian-Lagrangian two-phase flow approach. The Computational Fluid Dynamics (CFD) method is validated by experiments. The results indicate that the aerodynamic performance of the inlet, such as total pressure recovery, circumferential total pressure distortion index, and swirl distortion index, is all influenced by rain. Rain intensity and raindrop size are found to have a significant influence on the inlet aerodynamic performance. Raindrops impacting the inner wall surface of the inlet lead to the formation of water films. Furthermore, the water film has a non-negligible effect on the inlet velocity boundary layer. Crosswinds and headwinds affect the position of the water film formation. The swirl intensity of the airflow near the top wall of the aerodynamic interface plane (AIP) increases under rain conditions. These findings show the need to consider the impact of rain when designing and evaluating the aerodynamic performance of an aircraft engine.
Surfactant synergy on rheological properties, injectivity, and enhanced oil recovery of viscoelastic polymers
Authors: Chen Xin , Patel Viralkumar , Liu Jianbin , Liu Shun , Trivedi Japan
Published: February 2025

Surfactants synergized viscoelastic polymers can effectively balance the thickening and injectivity ability of the composite system and improve its enhanced oil recovery (EOR) effect. This work systematically studies the impact of concentration, compounding methods with surfactants, surfactant types, and salt concentrations on the rheological behavior of modified carboxymethyl cellulose (mCMC) based on the shear rheological properties. Then, injectivity experiments of the above solutions were carried out to compare the impact of differences in rheological properties on solution injection performance and optimize the injection parameters. Finally, oil displacement experiments were conducted to verify the mCMC viscoelasticity on the EOR effect. Experimental results show that surfactants can weaken the effect of shear on changing solution viscosity, and zwitterionic surfactants have the most obvious effect. The viscoelasticity of mCMC solution causes it to exhibit extensional viscosity, which gradually dominates as the shear rate increases, resulting in poor injection performance. Therefore, as the injection velocity increases, the injection factor has a maximum value (corresponding to the optimal injection velocity, about 10 ft/D). After that, increasing the injection velocity will greatly reduce mCMC injectivity under a higher extensional viscosity. When the shear rheology curves are similar and the injection velocity is 2 ft/D, mCMC can increase the oil recovery by 5.79% compared with Partially hydrolyzed polyacrylamide (HPAM), and the viscoelasticity contributes 16.95% to the EOR. As the injection velocity increases, the EOR of HPAM levels off, but the EOR of mCMC still increases significantly, which increases the viscoelastic EOR contribution to 25.98% at 10 ft/D.
Intelligent terminal structure response on anchorage foundation stability of Undersea Data Cabins affected by turbidity flow
Authors: Meng Zimin , Sun Huan , Zhu Yu , Fu Biao , Ye Zhenni
Published: February 2025

The construction of Undersea Data Center (UDC) infrastructure will be a crucial choice for countries worldwide in developing the numerical economy. The support structure foundation of Undersea Data Cabins serves as the safety bedrock of the entire underwater infrastructure project, This paper proposes a monitoring method that combines the support structure foundation and anchoring of UDC, develops an anchorage foundation and its intelligent terminal structure (ITS) for the UDC support structure, and conducts a physical similarity model experiment on the ITS perception of the UDC support structure anchorage foundation under extreme turbidity flow erosion. The results verify the adaptability of the ITS components installed on the UDC anchorage foundation in monitoring axial load loss. It was discovered that the axial load of the UDC anchorage foundation and the evolution of turbidity flow density under turbidity flow erosion exhibit a cubic polynomial function relationship, which can provide a quantitative relational criterion for the stability monitoring and early warning of the UDC anchorage foundation. This has significant safety implications for the development of UDC industrial clusters and commercial promotion.
Probing electronic and vibrational structures of TaCn−/0 (n = 2–4) using high-resolution photoelectron spectroscopy and theoretical calculations
Authors: Chen Xiaolin , Yan Shuaiting , Zhang Rui , Ning Chuangang
Published: February 2025

We report the high-resolution photoelectron spectroscopy of transition metal carbide cluster anions TaCn− (n = 2–4) using a cryogenic ion trap combined with the slow electron velocity imaging (cryo-SEVI) technique. From the vibrationally resolved photoelectron spectra and associated ab initio calculations, the electron affinities of TaCn (n = 2–4) were determined with high precision: 1.818(2), 2.202(5), and 2.431(2) eV, respectively. The electronic and vibrational structures observed in the photoelectron spectra were interpreted using density-functional theory and coupled-cluster singles and doubles with perturbative triples calculations. Both the neutral TaCn clusters and their anions exhibit planar C2v structures, where the Ta atom bridges each C atom. Furthermore, we observed the spin–orbit splitting in the ground state of TaC2 (X̃4B1), with a measured splitting of 256(25) cm−1. This splitting is well explained by the calculated E1/2(±3/2)−E1/2(±1/2) splitting of 216 cm−1, obtained using the MRCI+SOC method.
Statistical characteristics of heterogeneous ice nucleation temperature for sessile saltwater droplets on supercooled solid surfaces
Authors: Zhao Canjun , Hu Zhifeng , Lin Yukai , Wu Xiaomin , Ma Linhuan , Chu Fuqiang
Published: February 2025

The formation of ice nuclei in seawater droplets on supercooled solid surfaces is a prevalent phenomenon in nature and industrial applications. However, the statistical characteristics and mechanism of types of salt affecting their nucleation temperature remain poorly understood. This study experimentally investigates the nucleation process of saltwater droplets on solid surfaces, focusing on the effects of salinity, droplet volume, and the types of salt on nucleation temperature. The results reveal that the nucleation temperatures of saltwater droplets with varying salinities, volumes, and types of salt exhibit stochastic behavior and conform to a normal distribution. As salinity increases or droplet volume decreases, the nucleation temperature distribution broadens, shifts toward lower temperatures, and shows a decline in the average nucleation temperature. Furthermore, nucleation rates decrease with reduced droplet volume, increased salinity, or higher temperature. For droplets containing different types of salt, MgCl2 and CaCl2 droplets exhibit lower average nucleation temperatures and nucleation rates compared to LiCl, NaCl, and KCl droplets, with MgCl2 showing the lowest values. In contrast, LiCl, NaCl, and KCl droplets exhibit no notable differences. This trend is inversely correlated with the energy required during nucleation (the sum of dehydration energy and the energy barrier) for droplets containing different cations. These results offer valuable insight into the nucleation behavior and mechanisms of seawater droplets on supercooled solid surfaces, advancing the understanding and optimization of desalination technologies for seawater droplet freezing.
Active flow control for bluff body under high Reynolds number turbulent flow conditions using deep reinforcement learning
Authors: Chen Jingbo , Ballini Enrico , Micheletti Stefano
Published: February 2025

This study employs deep reinforcement learning for active flow control in a turbulent flow field of high Reynolds numbers at Re = 274 000. That is, an agent is trained to obtain a control strategy that can reduce the drag of a cylinder while also minimizing the oscillations of the lift. Probes are placed only around the surface of the cylinder, and a proximal policy optimization (PPO) agent controls nine zero-net mass flux jets on the downstream side of the cylinder. The trained PPO agent effectively reduces drag by 29% and decreases lift oscillations by 18% of amplitude, with the control effect demonstrating good repeatability. Control tests of this agent within the Reynolds number range of Re = 260 000 to 288 000 show that the agent's control strategy possesses a certain degree of robustness, with very similar drag reduction effects under different Reynolds numbers. Analysis using power spectral energy reveals that the agent learns specific flow frequencies in the flow field and effectively suppresses low-frequency, large-scale structures. Graphically visualizing the policy, combined with pressure, vorticity, and turbulent kinetic energy contours, reveals the mechanism by which jets achieve drag reduction by influencing reattachment vortices. This study successfully implements robust active flow control in realistically significant high Reynolds number turbulent flows, minimizing time costs (using two-dimensional geometrical models and turbulence models) and maximally considering the feasibility of future experimental implementation.
Internal structures of turbulent spots
Authors: Hu Ning , Du Bingyin , Lee Cunbiao
Published: February 2025

The evolution of turbulent spots over a flat plate is investigated using time-resolved tomographic particle image velocimetry. Timelines and material surfaces are used to visualize flow structures within the turbulent spots. The results reveal soliton-like coherent structures within the spots that act as three-dimensional (3D) waves, inducing wave-like peaks on material surfaces. The lift-up of these 3D waves and the downward movement of the surrounding fluid form high-shear layers, which serve as precursors to vortices at the edges of the turbulent spots. These findings suggest that 3D waves may serve as the fundamental structures of turbulent spots and play a dominant role in their development.
Spatial Patterning Analysis of Cellular Ensembles (SPACE) finds complex spatial organization at the cell and tissue levels
Authors: Schrom Edward C. , McCaffrey Erin F. , Sreejithkumar Vivek , Radtke Andrea J. , Ichise Hiroshi , Arroyo-Mejias Armando , Speranza Emily , Arakkal Leanne , Thakur Nishant , Grant Spencer , Germain Ronald N.
Published: February 2025

Spatial patterns of cells and other biological elements drive physiologic and pathologic processes within tissues. While many imaging and transcriptomic methods document tissue organization, discerning these patterns is challenging, especially when they involve multiple elements in complex arrangements. To address this challenge, we present Spatial Patterning Analysis of Cellular Ensembles (SPACE), an R package for analysis of high-plex spatial data. SPACE is compatible with any data collection modality that records values (i.e., categorical cell/structure types or quantitative expression levels) at fixed spatial coordinates (i.e., 2d pixels or 3d voxels). SPACE detects not only broad patterns of co-occurrence but also context-dependent associations, quantitative gradients and orientations, and other organizational complexities. Via a robust information theoretic framework, SPACE explores all possible ensembles of tissue elements—single elements, pairs, triplets, and so on—and ranks the most strongly patterned ensembles. For single images, rankings reflect differences from random assortment. For sets of images, rankings reflect differences across sample groups (e.g., genotypes, treatments, timepoints, etc.). Further tools then characterize the nature of each pattern for intuitive interpretation. We validate SPACE and demonstrate its advantages using murine lymph node images for which ground truth has been defined. We then detect new patterns across varied datasets, including tumors and tuberculosis granulomas.
Human beauty illustrates the economic impact of heritable physical traits
Authors: Hamermesh Daniel S. , Zhang Anwen
Published: February 2025

Intergenerational transmission of inequality is a central question in the social sciences. We use one trait, beauty, to infer how much parents’ physical characteristics transmit inequality across generations. Analyses of a large-scale longitudinal dataset in the United States, and a much smaller dataset of Chinese parents and children, show that increases in parents’ looks are associated with increases in their child’s looks. A large dataset of U.S. siblings shows a positive correlation of their beauty. The appropriate weighted average from the three samples shows that a one SD increase in ratings of both parents’ looks is associated with a 0.25 SD increase in their child’s. Coupling these estimates with those from large literatures measuring the impact of beauty on earnings and the intergenerational elasticity of income suggests that a one SD difference in parents’ looks is correlated with a 0.074 SD difference in their adult child’s earnings, about U.S. $2,170 annually.
Uncovering the hidden RNA virus diversity in Lake Nam Co: Evolutionary insights from an extreme high-altitude environment
Authors: Wu Lilin , Liu Yongqin , Shi Wenqing , Chang Tianyi , Liu Pengfei , Liu Keshao , He Yong , Li Zhaorong , Shi Mang , Jiao Nianzhi , Lang Andrew S. , Dong Xiyang , Zheng Qiang
Published: February 2025

Alpine lakes, characterized by isolation, low temperatures, oligotrophic conditions, and intense ultraviolet radiation, remain a poorly explored ecosystem for RNA viruses. Here, we present the first comprehensive metatranscriptomic study of RNA viruses in Lake Nam Co, a high-altitude alkaline saline lake on the Tibetan Plateau. Using a combination of sequence- and structure-based homology searches, we identified 742 RNA virus species, including 383 novel genus-level groups and 84 novel family-level groups exclusively found in Lake Nam Co. These findings significantly expand the known diversity of the
Orthornavirae
, uncovering evolutionary adaptations such as permutated RNA-dependent RNA polymerase motifs and distinct RNA secondary structures. Notably, 14 additional RNA virus families potentially infecting prokaryotes were predicted, broadening the known host range of RNA viruses and questioning the traditional assumption that RNA viruses predominantly target eukaryotes. The presence of auxiliary metabolic genes in viral genomes suggested that RNA viruses (families
f
.
0102
and Nam-Co_family_51) exploit host energy production mechanisms in energy-limited alpine lakes. Low nucleotide diversity, single nucleotide polymorphism frequencies, and pN/pS ratios indicate strong purifying selection in Nam Co viral populations. Our findings offer insights into RNA virus evolution and ecology, highlighting the importance of extreme environments in uncovering hidden viral diversity and further shed light into their potential ecological implications, particularly in the context of climate change.
The revised elastic field of an edge dislocation
Authors: Hirth J. P. , Anderson P. M.
Published: February 2025

We modify the traditional linear-elastic field of an edge dislocation. The modifications stem from symmetry and energy requirements imposed in terms of embedded (deformed) coordinates. These requirements are satisfied if a line force is added to the dislocation field. The modification to the stress field is expressed by coefficients that are a function only of Poisson’s ratio. Qualitatively, the field of the dislocation is increased in the glide direction and decreased in the climb direction. There are small changes to the field of a screw dislocation that do not entail the addition of a line force. Effects of nonlinearity, anisotropic elasticity, and image forces are briefly considered.
Amount content of H+ in hydrochloric acid (0.1 mol·kg-1)
Authors: Wu Bing , Liv Lokman , Gençtürk Tosun Serap , Zhang Jianying , Zhou Tao
Published: February 2025

Main text

The subsequent key comparison CCQM-K73.2018.3 was performed to demonstrate the capability of the participating institutes to measure the amount content of H+ in hydrochloric acid as a follow-up of the previous key comparison CCQM-K73.2018. A HCl solution of a slightly different composition to that in CCQM-K73.2018 was used.

TUBITAK UME requests this bilateral comparison. Both participants used high accuracy constant current coulometry for measurement. The agreement of the results was good. National institute of metrology P. R. China (NIM) acted as the coordinating laboratory and served as a link to the reference value of CCQM-K73.2018.

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

The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).
Probing the axion–photon coupling with space-based gravitational wave detectors
Authors: Gué Jordan , Hees Aurélien , Wolf Peter
Published: February 2025

We propose a simple modification of space-based gravitational wave (GW) detector optical benches which would enable the measurement of vacuum birefringence of light induced by axion dark matter through its coupling to electromagnetism. Specifically, we propose to change a half-wave plate by a circular polarizer. While marginally affecting the sensitivity to GW by a factor

2

, we show that such an adjustment would make future detectors such as LISA, TianQin, Taiji and Big-Bang Observer the most sensitive experiments at low axion masses.
Development of a lightweight cross-scale decoupling feature fusion network for surface defect detection in permanent magnets
Authors: Shu Shuangbao , Gao Xinyu , Zheng Changjie , Fu Yufeng , Wang Jiyao
Published: February 2025

Permanent magnet motors may suffer from imperceptible localized demagnetization due to surface damage during operation. This paper proposes a lightweight cross-scale decoupling feature fusion network (LCDFFN) for permanent magnets defect detection, which introduces separable convolution in the backbone and incorporates the adaptive multi-scale feature fusion with interactive attention mechanism to enhance small target detection. The adaptive attention module (AAM) and feature enhancement module based on dilated convolution are introduced in the feature fusion network, improving multi-scale object detection. Finally, the decoupled feature prediction network outputs the defect identification feature map. In addition, we also propose a novel fuzzy intersection over the union loss function. LCDFFN achieves a mAP@0.5 of 97.8%, with 108.4M parameters and a detection speed of 113.62 FPS. The proposed method significantly improves defect image detection for permanent magnets and is highly practical for industrial production.
Mitigating shuttle effect of the Li||S battery with Se-deficient commercial MoSe2 flakes
Authors: He Yao , Wang Lijing , Yang Sheng , Zhang Shaowei , Du Hongfang , Cui Dandan , Lin Liangxu
Published: February 2025

In lithium–sulfur batteries (LSBs), the dissolution of lithium polysulfides (LiPSs) triggers the shuttle effect to lose active materials irreversibly, leading to the fast deterioration of electrochemical performance. Rational designs on the separator membrane could mitigate the shuttle effect. However, the development of efficient separators economically remains a challenging task, aggressively limiting the commercial use of LSBs. This work reports the engineering of commercial molybdenum diselenides (MoSe2) flakes to mitigate the shuttle effect of LSBs, by forming rich Se vacancies via a potassium (K) intercalation and de-intercalation reaction. The Se vacancy in MoSe
x
flakes significantly enhances the adsorption capacity of LiPSs and accelerates the Li+ diffusion kinetics, thereby alleviating the shuttle effect and enhancing the energy storage performance. This directly improves the energy storage performance of the LSBs by incorporating the MoSe
x
flakes into the separator membrane, giving a high capacity retention rate of 94.6% at 2 C after 500 cycles, with a reversible specific capacity as high as 452 mAh g−1. This work offers a new strategy for the design and synthesis of vacancy rich transition metal chalcogenides for high-performance LSBs and beyond.
Improving the quality of back contact interface in Cu2ZnSn(S,Se)4 solar cells by inserting a thin Mg(OH)2 intermediate layer
Authors: Zhang Xingyu , Wang Lingling , Wang Yawei , Zhao Xiangyang , Fang Rong , Guo Rui , Zhou Yue , Zhang Xintong , Liu Yichun
Published: February 2025

Modifying the back contact interface plays a key role in improving the efficiency of Cu2ZnSn(S,Se)4 (CZTSSe) solar cells. Aiming at the phase decomposition and carrier recombination issues in the CZTSSe/Mo back contact interface, an ultra-thin Mg(OH)2 intermediate layer was introduced between the Mo substrate and the CZTSSe absorber layer. The Mg(OH)2 intermediate layer effectively suppressed the interface phase decomposition reactions and inhibited the generation of interface secondary phases. Meanwhile, during the high-temperature selenization process, the Mg2+ doped into CZTSSe at the back contact interface, reducing the defects and band offset at the CZTSSe/Mo interface. The performance of the device was improved, with a significant increase in efficiency compared to the control device. This work highlights the modification effect of Mg(OH)2 for improving back contact and also provides an easy-handling method to achieve high-performance CZTSSe solar cells.
Mechanical behaviour of cis-1,4-polyisoprene under uniaxial tension with silica and POSS filling: a coarse-grained molecular dynamics simulation
Authors: Wei Dahai , Zeng Fanlin , Cui Jianzheng , Wang Youshan
Published: February 2025

In this paper, the iterative Boltzmann inversion (IBI) method has been employed to develop the coarse-grained (CG) force field of cis-1,4-polyisoprene (PI) rubber and its silica-filled and POSS-filled composites. Uniaxial tension simulations have been conducted for the pure PI model, the silica-filled PI model, and the POSS-filled PI model, as well as their particle grafting and matrix cross-linking models. By examining the evolution of molecular chains, filled particles, and the entire matrix in terms of mechanical behaviour, it was found that particle-induced molecular chain straightening is the primary factor contributing to the elevated macroscopic stress level observed in the particle-filled PI model. However, the ungrafted silica particles do not result in an increase in the stress level of the system due to the weaker interactions. The grafting and matrix cross-linking processes serve to enhance this induced process, with the former increasing particle roughness and the latter increasing molecular chain roughness. In terms of the entire condensed system, the macroscopic stress level of the system is strongly correlated with the inhomogeneity of the microscopic strain. The inhomogeneity of the strain distribution in the system demonstrates the existence of a region of strain concentration, which leads to large deformations, resulting in the loosening of the structure and a decrease in the load-carrying capacity. The nucleation of microvoids in the system cannot be attributed to microscopic stress concentrations, which are more likely to occur in the weak interaction region. In POSS-filled systems, the weak interaction region is located between the substrate and the substrate, which explains the formation of microvoids in this region. In contrast, in silica-filled systems, the weak interaction region is between the substrate and the filler, resulting in microvoids forming at the filler-substrate interface. Silica can compensate for the weak interaction region by grafting and mixing with the POSS filler, which causes the nucleation of microvoids to shift to the substrate
Output prediction summary deep echo state network for multivariate chaotic time series forecasting
Authors: Wang Lei , Lun Shuxian
Published: February 2025

In this paper, a novel multi-reservoir model called output prediction summary deep echo state network (OPS-DESN) is proposed for multivariate time series forecasting. OPS-DESN consists of a series of chain-connected feature extraction modules and a re-prediction module. Firstly, the input sequence is chosen by calculating the Pearson correlation coefficient between each dimensional component of the original data and the target output. Secondly, the number of feature extraction modules in OPS-DESN equals the dimension of the input sequence. The single dimensional components in the input sequence are allocated to each feature extraction module in descending order of correlation degree. Each external input component is combined with the previous module output, they are input into the current module for prediction. The outputs of all feature extraction modules are collected and used as input to the re-prediction module for re-fitting. Thirdly, to further enhance the prediction accuracy of OPS-DESN, grey wolf optimizer is selected as the parameter tuning method. Finally, prediction experiments conducted on two sets of theoretical and two sets of actual series verify the prediction performance of OPS-DESN.