bluuebunny/crossref_metadata_2025 huggingface dataset:
Phase composition and dissociation processes in metal–ammonia solid solution
Authors: Shchetkin I. S. , Tarasenko G. I. , Osika E. A. , Tsoi G. M. , Dmitrenko I. M.
Published: November 2024

Sodium–ammonia solutions with various sodium concentrations were examined thermographically over the 77−200°K temperature range. The results indicate a heterogeneous state of frozen sodium–ammonia solutions. An analysis of the conditions under which these solutions are quenched confirms the feasibility of precipitating a structurally free phase richer in metal. The presence of such a metallized phase determines the anomalous physical properties of metal–ammonia solid solutions.
Interaction of dislocations with point defects and internal friction in superconductors
Authors: Miloshenko V. E. , Shunin G. E. , Roshchupkin A. M.
Published: November 2024

The electrostatic interaction of dislocations with point defects in a superconductor is discussed. It is shown that the interaction changes in the superconducting transition due to a diminution of the screening capacity of the system of conduction electrons. It is pointed out that the change in the electrostatic energy of interaction of a dislocation with a point defect is supported by experimental results on the internal friction of superconductors.
Kinetic equations for superconductors with paramagnetic impurities
Authors: Galaiko V. P. , Glushchuk N. I.
Published: November 2024

The Boltzmann kinetic equation for quasiparticles scattered by paramagnetic impurities in the case of “pure” superconductors is derived on the basis of the kinetic equations for the generalized electron-hole density matrix. The “mixing” of the electron and hole components of the excitation spectrum due to conservation of electric charge in a superconductor is investigated.
Shape of the cyclotron-resonance curve for metals in an inclined magnetic field
Authors: Aronov I. E. , Kaner É. A.
Published: November 2024

The shape of the cyclotron-resonance curve for metals in an inclined magnetic field is analyzed. The range of low inclination angles is considered, where Doppler splitting of resonance is observed. Asymptotically exact expressions are derived for the components of the surface-impedance tensor at the center and at the edges of the. resonance curve, applicable to the case of diffuse electron scattering at the interface. The entire resonance curve is described by interpolation formulas.
Irreversible component of the magnetoresistance of europium
Authors: Boyarskii L. A. , Dikovskii V. Ya.
Published: November 2024

The magnetoresistance of polycrystalline europium in magnetic fields up to 20 kOe strong was measured over the 4.2–80°K temperature range. On the basis of these experimental data, the present authors have separated and analyzed the hysteretic component of transverse magnetoresistance, this component being asociated with the reconstruction of the antiferromagnetic domains. This irreversible component of magnetoresistance has been found to decrease sharply at magnetic field intensities approaching some critical level. The temperature dependence of this critical field intensity was also measured. Simultaneous measurements of both the transverse and the longitudinal magnetoresistance have made it possible to split the irreversible component into an isotropic and an anisotropic part, with the latter found to be dominant.
Pressure dependence of the antiferromagnetic resonance in CuCl2·2H2O in the high-frequency branch of the spectrum
Authors: Galkin A. A. , Dan'shin N. K. , Vetchinov A. V.
Published: November 2024

The antiferromagnetic resonance in CuCl2·2H2O in the frequency range 25−36.5 GHz was investigated as a function of temperature (in the range 1.65−4.2°K) and pressure (0−9.7 kbar). The Néel temperatures under pressure were estimated from the experimental data, and the resonance fields and magnetic anisotropy parameter were found as functions of temperature and pressure.
Electron interactions and the crystalline lattice of rare earth metals
Authors: Beznosov A. B. , Nikol'skii G. S.
Published: November 2024

The effect of electron interactions on the crystalline lattice properties of rare earth metals is analyzed. A number of calculations are performed for conduction band states in the plane wave approximation, including the contribution of exchange interaction with consideration of the 4f electrons to the observed value of the atomic volume. The properties of the model used are compared with experimentally measured crystalline lattice parameters, thermal expansion, and magnetization. Several aspects of the nature of lanthanide magnetic and lattice properties are evaluated.
Charged helium surface in a capacitor
Authors: Chernikova D. M.
Published: November 2024

The role of finite geometry effects in the appearance and development of an instability of a charged helium surface is studied.
Measurement of the molar volumes of liquid solutions of He3 and He4 under a pressure of up to 100 atm, at temperatures of 1.5−4.2° K
Authors: Bogoyavlenskii I. V. , Yurchenko S. I.
Published: November 2024

By measuring the dielectric constant, the molar volumes were determined of liquid He3, He4 and their solutions, with He3 contents of 35.2, 50.7, and 65.1%, under a pressure of up to 100 atm over the temperature range 1.5−4.2°K. The excess molar mixing volume of the solutions was traced, as a function of the pressure, temperature and concentration. At a pressure in excess of 7.5 atm, the possibility arises for the direct comparison of the measured molar volumes of solutions of He3 and He4 with the calculated values, within the scope of the Prigogine isotopic solution model. The theoretical values of the excess molar volume were found to be smaller than the experimental values by a factor of 2.
Formation of superconducting phase nuclei at defects
Authors: Nechiporenko I. N.
Published: November 2024

The problem of the origination of a superconducting nucleus in an external magnetic field for type I superconductors is considered in a pure crystal and in a crystal containing point defects, in the specimen bulk and on the surface. The shape of the nucleus, the energy barriers to nucleus formation, and the changes in the critical fields with the concentrations of defects are found. It is shown that the presence of defect clumps of the necessary sign in the crystal (of dilatation center type) makes possible the existence of a superconducting fluctuon in this group of defects. The range of parameters for fluctuon existence is determined and it is shown that the unusual behavior observed in contaminated aluminum at a n−s transition can be explained by the formation of a superconducting fluctuon.
Exciton pairing and superconductivity in layered compounds
Authors: Kulik I. O. , Shevchenko S. I.
Published: November 2024

A new type of electronic phase transition in low-dimensional (layered) crystals with alternating layers of conduction electrons and holes is predicted; it is related to pairing by spatially separated carriers. We show the existence of “longitudinal superfluidity,” diamagnetic response to a longitudinal magnetic field, and “transverse superfluidity,” the analogs of de and ac quantum interference in a transverse field. These effects occur when both correlation (Coulomb) and tunneling (Josephson) interactions of adjacent layer electrons are included, while tunneling transitions (T12) under the condition T12≪ Δ (Δ is the energy gap) lead only to generation of critical field values E⊥, H‖ . At these values “destabilization” starts of the phase of the order parameter and of related quantum coherence effects (“superfluidity”).
Acoustic cyclotron resonance and the interaction of sound with cyclotron waves in semimetals
Authors: Zimbovskaya N. A. , Okulov V. I.
Published: November 2024

It is shown that under conditions of high-frequency acoustic cyclotron resonance in very pure samples of semimetals the sound can interact with short longitudinal cyclotron waves, producing a shift in the resonance absorption peak and leading to the appearance of coupled waves. Estimates are made for bismuth of the interaction parameters required for this effect to be observed.
Calculation of spin wave damping at low temperatures
Authors: Bar’yakhtar V. G. , Lutovinov V. S. , Ol’khov O. A. , Sobolev V. L
Published: November 2024

Second-order perturbation theory in the spin-wave interaction Hamiltonian is shown to be inadequate for the calculation of magnon damping at low temperatures in easy-plane antiferromagnets. Subsequent orders (third and fourth) must be taken into account as the contribution from them may exceed that from the second.
Galvanomagnetic properties and magnetization of amorphous iron films
Authors: Kuz’menko V. M. , Mel’nikov V. I. , Sudovtsov A. I.
Published: November 2024

A study is made of the Hall effect in the thin iron films produced by low-temperature condensation. The dependence of the Hall resistance on magnetic induction is used to determine the saturation magnetization of the amorphous modification of iron.
Localized vibrations in crystal associated with straight screw dislocation
Authors: Dubrovskii I. M. , Kovalev A. S.
Published: November 2024

An equation is obtained which describes the vibrations of a crystal containing a straight screw dislocation. It is shown that, irrespective of the conditions in the dislocation core, this equation may have solutions in the form of the modified Bessel function with an imaginary index. These solutions describe bands of localized vibrations. The dispersion laws for these bands are found for simple cubic, face centered cubic, and body centered cubic lattices.
A theory of metamagnetic dielectrics
Authors: Akhiezer I. T.
Published: November 2024

The behavior of a dielectric magnet in an external magnetic field is studied on the basis of a microscopic model. Because of mutual electron interaction the symmetry of the ground state turns out to be below the symmetry of the Hamiltonian, whereupon anomalous averages occur— the magnetization and the antiferromagnetism vector. As the external magnetic field increases, such a crystal can behave as an ordinary antiferromagnet, an ordinary metamagnet, or an anomalous metamagnet of syderite type characterized by the phase sequence collinear antiferromagnet–collinear ferrimagnet–ferromagnet, depending on the values of the parameters in the interaction Hamiltonian.
Influence of trajectory electron transfer on the anomalous penetration of ultrasound in pure gallium
Authors: Shepelev A. G. , Ledenev O. P. , Filimonov G. D.
Published: November 2024

The anomalous penetration of longitudinal ultrasound (70 and 150 MHz) frequency in pure single-crystal gallium is studied experimentally in a weak magnetic field H⊥k at low temperature. A retarded ultrasound signal (relative to the main one) is detected. An investigation of new magnetoacoustic effects permitted the determination of a temperature dependence of the electron collision frequency with thermal phonons νe,ph(T) ∼ T3 for gallium. It is detected that anomalous oscillations in the propagation velocity of ultrasound and signal pulses being propagated by electron transfer in a metal exist even for a field almost parallel to k.
Structuring in thin films during meniscus-guided deposition
Authors: de Bruijn René , Darhuber Anton A. , Michels Jasper J. , van der Schoot Paul
Published: November 2024

We theoretically study the evaporation-driven phase separation of a binary fluid mixture in a thin film deposited on a moving substrate, as occurs in meniscus-guided deposition for solution-processed materials. Our focus is on the limit of rapid substrate motion where phase separation takes place far away from the coating device. In this limit, demixing takes place under conditions mimicking those in a stationary film because substrate and film move at the same speed. We account for the hydrodynamic transport of the mixture within the lubrication approximation. In the early stages of demixing, diffusive and evaporative mass transport predominates, consistent with earlier studies on evaporation-driven spinodal decomposition. In the late-stage coarsening of the demixing process, the interplay of solvent evaporation, diffusive, and hydrodynamic mass transport results in several distinct coarsening mechanisms. The effective coarsening rate is dictated by the dominant mass transport mechanism and therefore depends on the material properties, evaporation rate, and time: slow solvent evaporation results in initially diffusive coarsening that for sufficiently strong hydrodynamic transport transitions to hydrodynamic coarsening, whereas rapid solvent evaporation can preempt and suppress hydrodynamic and diffusive coarsening. We identify a novel hydrodynamic coarsening regime for off-critical mixtures, arising from the interaction of the interfaces between solute-rich and solute-poor regions in the film with the solution–gas interface. This interaction induces a directional motion of solute-rich droplets along gradients in the film thickness, from regions where the film is relatively thick to where it is thinner. The solute-rich domains subsequently accumulate and coalesce in the thinner regions.
Tunable ultrabroadband hybrid terahertz emitter combining a spintronic and a GaSe source
Authors: Alostaz Afnan , Gueckstock Oliver , Tong Junwei , Kredl Jana , In Chihun , Münzenberg Markus , Schneider Claus M. , Kampfrath Tobias , Seifert Tom S.
Published: November 2024

Terahertz (THz) time-domain spectroscopy (TDS) is a sensitive approach to material characterization. It critically relies on a sufficiently large bandwidth, which is not straightforwardly available in typical THz-TDS systems that are often limited to below 3 THz. Here, we introduce a hybrid THz-source concept based on a spintronic THz emitter (STE) deposited onto a thin, free-standing GaSe nonlinear crystal. By tuning the magnetic state and the phase-matching parameters of the hybrid emitter, we generate an ultrabroadband spectrum covering the full range from 1 to 40 THz. We achieve significantly enhanced spectral amplitudes above 10 THz compared to the bare STE, resulting in ultrashort THz-pulse durations down to 32 fs. Finally, we demonstrate the straightforward tunability of the shape of the few-cycle pulse from symmetric to antisymmetric.
Acoustically propelled winged macroparticles
Authors: Enriquez Adriana , Sack Achim , D’Angelo Olfa
Published: November 2024

Self-propelled particles harvest and harness energy from their environment, transforming it into a controlled force that propels their motion. We present a mechanism to propel active macroparticles using low frequency noise (10–200 Hz). Thin polymer plates (wings) are acoustically excited at their second natural frequency; the mass of air displaced generates a counter-force, which propels the macroparticles. We show that the magnitude and direction of the propelling force can be tweaked through the wing’s shape, dimensions, and orientation. Finally, we design a macroparticle with bidirectional rotation: its rotation direction can be inverted by changing the frequency at which it is excited.
New insights into the dissolution mechanisms of iron oxides and combusted iron particles in oxalic acid
Authors: Lausch M. , Zimina A. , Bao J. , Pashminehazar R. , Etzold B. J. M. , Kramm U. I. , Grunwaldt J.-D. , Hussong J.
Published: November 2024

The influence of oxidation state and crystalline structure on the dissolution mechanisms of both pure iron oxides and combusted iron particles in aqueous oxalic acid (0.5 mol/l) at 60 °C was systematically investigated. Dissolution experiments were carried out in a temperature-controlled, continuous-flow capillary reactor, allowing for the removal of reaction products and thereby suppressing the autocatalytic reaction mechanism. The non-reductive dissolution of α-Fe2O3 was observed through in situ x-ray absorption measurements. In contrast, the dissolution of spinel-type oxides such as γ-Fe2O3 and Fe3O4 proceeded reductively, indicated by gradual changes in characteristic spectral features. Given that γ-Fe2O3 and Fe3O4 share a similar crystal structure but differ in the nominal oxidation state, this implies that the phase composition is decisive for the reductive dissolution. For mixed-phase particles consisting of spinel and rhombohedral phases (maghemite and hematite), the preferential dissolution of the spinel phase was observed. Despite the similar bulk composition of spinel and rhombohedral phases in the combusted iron particles (as confirmed by Mössbauer spectroscopy and x-ray diffraction analysis), dissolution predominantly follows a non-reductive pathway, with no preferential dissolution of the γ-phase. This unique dissolution behavior of combusted iron particles arises from their layered microstructure.
Lagrangian formulation of nuclear–electronic orbital Ehrenfest dynamics with real-time TDDFT for extended periodic systems
Authors: Xu Jianhang , Zhou Ruiyi , Li Tao E. , Hammes-Schiffer Sharon , Kanai Yosuke
Published: November 2024

We present a Lagrangian-based implementation of Ehrenfest dynamics with nuclear–electronic orbital (NEO) theory and real-time time-dependent density functional theory for extended periodic systems. In addition to a quantum dynamical treatment of electrons and selected protons, this approach allows for the classical movement of all other nuclei to be taken into account in simulations of condensed matter systems. Furthermore, we introduce a Lagrangian formulation for the traveling proton basis approach and propose new schemes to enhance its application for extended periodic systems. Validation and proof-of-principle applications are performed on electronically excited proton transfer in the o-hydroxybenzaldehyde molecule with explicit solvating water molecules. These simulations demonstrate the importance of solvation dynamics and a quantum treatment of transferring protons. This work broadens the applicability of the NEO Ehrenfest dynamics approach for studying complex heterogeneous systems in the condensed phase.
The Champati Slide
Authors: Pudasaini Shiva P. , Dangol Bekha R. , Tiwari Chet N. , Kafle Jeevan , Pokhrel Puskar R. , Kattel Parameshwari
Published: November 2024

Here, we report some novel findings of chute experiments with native Nepalese granular seeds, called Champatis, and when mixed with other food grain of a fundamentally different physical properties, Silam. The epitomic supergrain Champati exhibits complex frictional, spin, and rolling motion. We hypothesize that the Champati slide results in an essentially unique dynamical spreading, separation from other grains, mobility, run-out, and deposition morphology. Particularly, the surface anatomy of Champati acted vitally in characterizing these aspects. We reveal spectacular dynamical flow–obstacle interaction and depositional behavior of Champati and the mixture slide. Champati slide manifests hyper-spreading in the run-out. Soon after the mass hits the ground, the behavior is unprecedented and appears to be hardly predictable, mainly around the frontal periphery. The very special properties of Champatis control the frontal spreading, rapid grain marching, and their zig-zag sporadic motion. Particle rolling, spinning, exceptionally lower frictional energy dissipation, and grain collision played the major role resulting in an unexpectedly longer travel time and distance, explaining the astonishing hypermobility of Champati grains. The obstacle substantially changes the flow dynamics as the Champati exhibits high object mobilization capacity. Due to the unique property of the Champati, the eye-catching, amazingly strong separation of Champati from Silam evolves swiftly right after the flow inception, and the process intensifies quickly. The separation length characterizes the complex interfacial momentum exchange between the phases in the mixture. The separation length between the frontal Champatis and Silam grains increases exceptionally as it does between the main body and the exclusively Silam-covered tremendously long tail of the flow in the inclined portion of the channel. These results may be useful in better understanding the phase separation, superwide-spreading and hypermobility of some geological flows, including fragmented rock avalanches, probably helping resolve some relevant standing challenges.
Response of a 4-nitrothiophenol monolayer to rapid heating studied by
vibrational sum frequency spectroscopy
Authors: Linke Matthias , Multhaup Joshua , Hasselbrink Eckart
Published: November 2024

A monolayer of 4-nitrothiophenol adsorbed on an Au substrate was heated by illuminating the substrate with a 19 ps laser pulse of 532 nm wavelength. Within 91 ps, the temperature of the sample increased from room temperature by 113 K. Vibrational sum frequency spectroscopy was used to characterize the adsorption geometry of the molecules in the ordered domains in the monolayer film. Upon heating, the initially ordered monolayer largely lost its structure. While the molecules are initially tilted by about 50° with respect to the surface normal, the analysis indicates that the mean tilt angle increased to 80° with a spread for individual molecules of up to a tilt angle of 40° upon heating. The evolution of this loss of order lagged about 100 ps behind the temperature rise of the substrate.
A general solution of consolidation for a double-layer foundation soil induced by pre-excavation dewatering with bottom reinforcement considering delayed responses of water table
Authors: Yang Weitao , Xiao Liang , Mei Guoxiong
Published: November 2024

Precisely predicting soil deformation at each construction stage of foundation pit engineering is crucial for enhancing construction safety standards. However, the mechanics of ground settlement, both inside and outside foundation pits caused by pre-dewatering in an unconfined aquifer, remain unclear. Hence, this study proposes a semi-analytical solution that considers factors, such as soil stratification, pit bottom reinforcement, and unsteady pumping-induced flow in the unconfined aquifer, using finite Fourier transform and boundary transformation techniques. It verifies the acceptability of the proposed solution by comparing experimental and numerical results from COMSOL Multiphysics. A detailed parametric analysis is conducted to discuss how pit reinforcement parameters, specific yield, and soil stratification influence the behaviors of drawdown and deformation. The results indicated that increasing the reinforcement thickness at the pit bottom and reducing the permeability of the reinforcement layer can effectively mitigate soil deformation and drawdown. In contrast, the compression modulus of the reinforcement layer affects only the ultimate value of deformation. In addition, a larger specific yield significantly delays the rate of drawdown and deformation but does not impact their final values. For double-layer foundation soils, the final value of deformation and drawdown is reduced when the lower layer has higher permeability, resulting in less time for settlement completion. This study provides a theoretical reference for the engineering design of foundation pit projects.
Investigation and insights on the on-demand generation of monodispersed emulsion droplets from a floating capillary-based open microfluidic device
Authors: Deng Yueming , Xie Shuting , Li Zhengguang , Yang Ruizhi , Liu Zhenping , Yao Jiyuan , Zhang Haopeng , Jin Mingliang , Shui Lingling
Published: November 2024

Simple and stable generation of monodispersed droplets with volume from picolitre to nanoliter is one of the key factors in high-throughput quantitative microreactors for chemical and biomedical applications. In this work, an efficient method that could realize simple manipulating microflow with a broad operation window for preparing monodispersed droplets with controllable diameter is developed. The microfluidic device is constructed by inserting a capillary with an oblique angle (α) into the continuous phase, named a floating capillary-based open microfluidic device (FCOMD). The transition of droplet-generating mode between dripping and jetting can be achieved by changing capillary number and α. A computational model based on the volume-of-fluid/continuum-surface-force method to explain the controllability of α on the droplet formation regime and droplet breakage, verifying the synergistic effect of ΔP and Fb, facilitates the droplet pinching. A descending order of Pn of capillary with different α is that 45° > 30° > 15° > 60° > 75°, leading to the same order of generated droplet’s D. When compared with the traditional capillary co-flow device, the generating throughput of the integrated FCOMD obtained by integrating different numbers of capillaries is at least ten times. Moreover, water in oil, oil in water double-emulsion, colloidal dispersed droplets, and liquid crystal droplets with diameters ranging from 25 to 800 μm are prepared on-demand by the FCOMD, indicating the universality of the microfluidic device. Thus, the FCOMD shows the features of simplicity, practicability, and flexibility, offering valuable guidance for generating controllable droplets with wide size change and showing a great potential application in material science, foods, pharmaceuticals, and cosmetics.
Effects of a breakwater on a floating solar farm in heading and oblique waves
Authors: Zou Detai , Wei Yujia , Ou Binjian , Zhang Chao , Chu Shengnan , Huang Luofeng
Published: November 2024

Floating photovoltaic (FPV) solar farms have gained significant research and industrial interest in recent years. However, to support its deployment in abundant ocean space, FPV is required to be protected against wave loading. Thus, the usage of a breakwater in front of a floating solar farm is particularly promising. In this work, a time-domain simulation model for an array of FPV solar units in heading and oblique waves was established. Following validation against experiments, the model was used to predict the wave-induced motion and loading responses of each floating solar unit in an array, first without a breakwater, and subsequently with a breakwater. By comparison, it was found that a breakwater can reduce the wave-induced motions of a floating solar farm by up to 56%, alongside up to 55% reduction of loading on the joints between FPV units. However, the breakwater is less effective in relatively long waves and could induce some increase in loading on joints, signifying future work to optimize the design of the breakwater based on the intended environmental condition. Overall, the present results provide insights into a practical breakwater solution for FPV in offshore and coastal conditions, supporting the long-term development of this industry.
High-precision measurement of the magneto-optical Faraday effect via difference weak measurements
Authors: Wang Zhihui , Wang Bo , Zheng Xuan , Jiensibieke Liza , Wang Junpeng , Niu Sujian , Li Zhaoxue , Yang Xining
Published: November 2024

We propose a modified difference weak measurement scheme that permits precise measurements of the magneto-optical Faraday effect. By making normalized difference processing for a set of post-selected light intensity, a linear-response regime with a significant weak-value amplification effect is established. In the proof-of-principle experiment, we measure the magnetic intensity using the polarization system and achieve precision at the order of ∼10−7 T. Our scheme can be applied to measure other magneto-optical effects, providing a method for future ultra-sensitive sensing and metrology in magnetic physics.
Design and analysis of a hundred-watt G-band traveling wave tube
Authors: Li Hongjing , Liu Wenxin , Zhang Zhiqiang , Zhao Kedong , Jin Zhihao
Published: November 2024

In this paper, a hundred-watt level traveling wave tube operating in the G-band is designed and analyzed. A non-semi-arc folded waveguide (FW) slow wave structure (SWS) is adopted to achieve high output power. Compared with the conventional FW, this structure has a higher coupling impedance, which is beneficial for beam–wave interaction. To further improve the efficiency of beam–wave interaction, phase velocity taper technology is adopted in SWS. A diamond pill-box output window is designed for electromagnetic wave input and output in SWS. In addition, the electron optics including a Pierce electron gun and a periodic permanent magnet focusing system are designed for emitting and constraining the electron beam. Using CST PIC solver for simulation, the results show that under a 23 kV and 80 mA electron beam, the maximum output power of the SWS is 132.7 W and the saturated gain is 36.5 dB. The bandwidth for output power greater than 100 W is 12 GHz. A pill-box window is designed and fabricated, and experimentally measured S11 is better than −13 dB and S21 is better than −1.3 dB in 213–229.5 GHz. The electron optics generate 79 mA current at 23 kV voltage.
Defiltering turbulent flow fields for Lagrangian particle tracking using machine learning techniques
Authors: Oura Tomoya , Fukagata Koji
Published: November 2024

We propose a defiltering method of turbulent flow fields for Lagrangian particle tracking using machine learning techniques. Numerical simulation of Lagrangian particle tracking is commonly used in various fields. In general, practical applications require an affordable grid size due to the limitation of computational resources; for instance, a large-eddy simulation reduces the number of grid points with a filtering operator. However, low resolution flow fields usually underestimate the fluctuations of particle velocity. We thus present a novel approach to defilter the fluid velocity to improve the particle motion in coarse-grid (i.e., filtered) fields. The proposed method, which is based on the machine learning techniques, intends to reconstruct the fluid velocity at a particle location. We assess this method in a priori manner using a turbulent channel flow at the friction Reynolds number Reτ=180. The investigation is conducted for the filter size, nfilter, of 4, 8, and 16. In the case of nfilter=4, the proposed method can perfectly reconstruct the fluid velocity fluctuations. The results of nfilter=8 and 16 also exhibit substantial improvements in the fluctuation statistics although with some underestimations. Subsequently, the particle motion computed using the present method is analyzed. The trajectories, the velocity fluctuations, and the deposition velocity of particles are reconstructed accurately. Moreover, the generalizability of the present method is also demonstrated using the fields whose computational domain is larger than that used for the training. The present findings suggest that machine learning-based velocity reconstruction will enable us precise particle tracking in coarse-grid flow fields.
Aerodynamic interference effect and flow field mechanism of two tandem rectangular columns with a small width–thickness ratio at a high Reynolds number
Authors: Jiang Huimin , Liu Xiaobing , Ruan Lijun , Chen Anjie , Yang Qun
Published: November 2024

This paper conducted wind tunnel tests and large eddy simulations to study the aerodynamic interference effect and flow field mechanism of two tandem rectangular columns with a small width–thickness ratio (B/D = 0.25) at a high Reynolds number (Re = 2.1 × 105). The spacing ratio (L/B) varied from 0.2 to 20. Results showed that single-bluff body, reattachment, and co-shedding regimes occur at 0.2 ≤ L/B < 3, 3 ≤ L/B < 10, and 12 < L/B ≤ 20, respectively. In the single-blunt body regime, the mean drag coefficient of the upstream column, the fluctuating lift coefficient of the downstream column, and the Strouhal number of both columns are significantly amplified compared to a single column. These amplification effects are linked to the reattachment of the recirculation flow between columns and a reduced wake recirculation length. In the reattachment regime, the amplification effects in the mean drag coefficient and the fluctuating lift coefficient are diminished, but the Strouhal number still shows a marked amplification due to the short wake recirculation length. In the co-shedding regime, the amplification effects in aerodynamic force coefficients disappear. In addition to the three classic flow regimes, a bistable flow regime was identified at 10 ≤ L/B ≤ 12, where the aerodynamic characteristics observed in the reattachment and the co-shedding regimes alternate randomly at irregular time intervals.
Automated potential energy surface development and quasi-classical dynamics for the F− + SiH3I system
Authors: Molnár Balázs J. , Dékány Attila Á. , Czakó Gábor
Published: November 2024

We report a potential energy surface (PES) development for the F− + SiH3I system to study its gas-phase reactions through quasi-classical dynamics simulations. The PES is represented by a full-dimensional permutationally invariant polynomial fitted to composite coupled cluster energy points obtained at the ManyHF-[CCSD-F12b + BCCD(T) − BCCD]/aug-cc-pVTZ(-PP) level of theory. The development was automated by Robosurfer, which samples the configurational space, manages ab initio calculations, and iteratively extends the fitting set. When selecting the ab initio method, we address two types of electronic structure calculation issues: first, the gold standard CCSD(T)-F12b is prone to occasional breakdown due to the perturbative (T) contribution, whereas CCSD-F12b + BCCD(T) − BCCD, with the Brueckner (T) term, is more robust; second, the underlying Hartree–Fock calculation may not always converge to the global minimum, resulting in highly erroneous energies. To mitigate this, we employed ManyHF, configuring the Hartree–Fock calculations with multiple initial guess orbitals and selecting the solution with the lowest energy. According to the simulations, the title system exhibits exceptionally high and diverse reactivity. We observe two dominant product formations: SN2 and proton abstraction. Moreover, SiH2F− + HI, SiHFI− + H2, SiH2FI + H−, SiH2 + FHI−, SiH2 + HF + I−, and SiHF + H2 + I− formations are found at lower probabilities. We differentiated inversion and retention for SN2, both being significant throughout the entire collision energy range. Opacity- and excitation functions are reported, and the details of the atomistic dynamics are visually examined via trajectory animations.
Viscoelastic measurements of abscess fluids using a magnetic stress rheometer
Authors: Shih A. , Chung S. J. , Shende O. B. , Herwald S. E. , Vezeridis A. M. , Fuller G. G.
Published: November 2024

Abscesses, pockets of fluid caused by infections in the human body, are typically treated in hospitals by draining the fluid through a catheter. However, the viscous and heterogeneous nature of the fluid often leads to prolonged treatment duration or even drainage failure. Furthermore, current practice relies only on qualitative observations of viscosity for catheter size selection, with little quantitative data to guide this parameter. In this work, we introduce a compact magnetic stress rheometer platform to examine the rheological response of nine different abscess fluids under shear stress. A magnetic field applies a force to a probe that induces it to shear the underlying abscess fluid. Its spatiotemporal displacement is measured, resulting in the determination of creep compliance. The results are well-fitted to a 5-element viscoelastic model, providing a quantitative and robust prediction of abscess fluid rheology for a variety of etiologies. We show that while viscoelastic parameters between abscess fluids of different etiologies can span five orders of magnitude, zero-shear viscosity should be sufficient in future predictions of drainage flow rates. The custom-built instrument we have developed is portable, inexpensive, and sterile-compatible, serving as an ideal platform for point-of-care analyses in clinical settings to facilitate catheter selection and enable healthcare workers to devise optimal treatment strategies for each patient. Moreover, the versatility of our platform extends its potential application to rheological measurements in diverse medical contexts.
An explicitly correlated potential energy surface for N2–OCS complex: Out-of-plane motion and tunneling dynamics
Authors: Zheng Rui , Cheng Tong , Liu Tongyu , Tian Yanshan
Published: November 2024

A four-dimensional potential energy surface (4D-PES) has been constructed for the N2–OCS complex. The PES is achieved by applying the explicitly correlated coupled cluster method, which incorporates single, double, and perturbative triple excitations [CCSD(T)-F12a], along with the augmented correlation consistent triple zeta (aug-cc-pVTZ) basis set. The rovibrational levels are precisely determined and assigned through bound state calculations and wavefunction analysis. The calculated transition frequencies reproduce the experimental observations accurately, achieving an RMSE of 0.0005 cm−1 for the 23 rotational transitions (J ≤ 6, Ka ≤ 2). The R-φ contour plot of the wave function clearly demonstrates the unambiguous delocalization of the dihedral angle, and the averaged geometry of the ground vibrational state is determined to be non-planar with φ = 90°. To obtain a quantitative analysis of this phenomenon, we expanded the 3H-solution model [Guo et al., J. Quant. Spectrosc. Radiat. Transfer 309 (2023) 108711] from a three-dimensional system (Ar–AgF) to a nine-dimensional system (N2–OCS). Based on this model, the tunneling splitting was calculated to be 0.0822 cm−1, which excellently matches the experimental result of 0.0817 cm−1. The excellent agreement between the theoretical and experimental results suggests that the wavefunction delocalization and out-of-plane motion can be attributed to the tunneling effects in the ground vibrational state.
Electrospray modes of liquids in electrohydrodynamic atomization: A review
Authors: Wang Zhentao , Chen Yongzhong , Xue Jiayi , Li Bin , Wang Jue , Dong Qingming
Published: November 2024

Liquid is sprayed from a capillary tube and further disperses into fine drops in various means, when subjected to an externally electric field, where the process of liquid jet formation and breakup into drops is usually named as electrohydrodynamic atomization or electrospray (ES). Electrospray has been extensively applied into many fields because uniform and highly charged drops, easy controllability in size and motion, and various ES modes are available to match the requirements of various applications. In present work, recent progresses in theory and numerical work to explain electrospray structure and drop formation were summarized. According to the geometry of liquid ejection and its further disintegration, main ES modes including dripping, micro-dripping, spindle, cone-jet, multi-jet, and simple-jet have been designated. The transformation of ES modes due to variation of electric potential, liquid flow rate, and physical parameters, the formation of curved liquid surface, and jet fragmentation behavior in these ES modes were also reviewed, as well as generated drops dynamics. In a rational range of flow rate, dripping, micro-dripping, spindle, cone-jet, multi-jet modes successively emerge with an increase in electric potential, and otherwise, an irregular instability may occur. In addition, the simple jet mode occurs in a relatively large flow rate. The insight into ES modes may fully understand mechanism and technology of electrospray and further promote more extensive application in industrial fields.
Wake characteristics of near-wall submerged bluff bodies with varying streamwise length
Authors: Edegbe M. , Nasif G. , Balachandar R.
Published: November 2024

This study aims to investigate the effect of streamwise length on the wake characteristics of submerged sharp-edged bluff bodies in the presence of an underbody gap using large eddy simulation. To this end, three bodies with identical width (W) and height (h), but varying only in their streamwise lengths (L) were employed resulting in streamwise elongation ratios of L/h = 1, 2, and 3, respectively. The underbody gap between the bottom face of the body and the wall was fixed at 0.14 h for all cases. A fully developed turbulent boundary layer with a thickness of 3.6 h was used as the approaching flow. It was noted that the mean flow and turbulent stresses were significantly affected by the streamwise length. Premultiplied frequency spectra of the velocity fluctuations were utilized to examine the fluctuating properties of the wake. A single dominant vortex shedding frequency was observed for L/h = 1 and 3, whereas dual mode vortex shedding was noted for L/h = 2. The latter case exhibited an intermittent reattachment on the top surface of the body. The fluid structures evaluated using the λ2 criterion, indicated that they were strongly influenced by L/h. Interestingly, even with the presence of a gap, a weak horseshoe vortex which occurred intermittently was captured close to the bed for the three cases.
The interplay of plasticity and elasticity in elastoviscoplastic flows in wavy channels
Authors: Abdelgawad Mohamed S. , Haward Simon J. , Shen Amy Q. , Rosti Marco E.
Published: November 2024

Elastoviscoplastic (EVP) fluids, which exhibit both solid-like and liquid-like behaviors depending on the applied stress, are critical in industrial processes involving complex geometries such as porous media and wavy channels. In this study, we investigate how flow characteristics and channel design affect EVP fluid flow through a wavy channel, using numerical simulations supported by microfluidic experiments. Our results reveal that elasticity significantly influences flow dynamics, reducing pressure drops and expanding unyielded regions. Notably, we find that even minimal elasticity can shift the flow from steady to time-dependent regimes, a transition less pronounced in viscoelastic fluids. Additionally, we show that the development of stagnation regions can be prevented when using a modified EVP fluid with enhanced elasticity, thus providing a full global yielding of the material. This study elucidates the role of elasticity in modifying flow patterns and stress distribution within EVP fluids, offering insights into the optimization of industrial applications, such as the displacement of yield stress fluids in enhanced oil recovery, gas extraction, cementing, and other processes where flow efficiency is critical.
A global assessment of plant–mite mutualism and its ecological drivers
Authors: Myers Andrew , Martin Bruce , Yonenaga Jenna , Agrawal Anurag A. , Weber Marjorie G.
Published: November 2024

Mutualisms are mediated by adaptive traits of interacting organisms and play a central role in the ecology and evolution of species. Thousands of plant species possess tiny structures called “domatia” that house mites which protect plants from pests, yet these traits remain woefully understudied. Here, we release a worldwide database of species with mite domatia and provide an evaluation of the phylogenetic and geographic distribution of this mutualistic trait. With >2,500 additions based on digital herbarium scans and published reports, we increased the number of known species with domatia by 27% and, importantly, documented their absence in >4,000 species. We show that mite domatia likely evolved hundreds of times among flowering plants, occurring in an estimated ~10% of woody species representing over a quarter of all angiosperm families. Contrary to classic hypotheses about the evolutionary drivers of mutualism, we find that mite domatia evolved more frequently in temperate regions and in deciduous lineages; this pattern is concordant with a large-scale geographic transition from predominantly ant-based plant defense mutualisms in the tropics to mite-based defense mutualisms in temperate climates. Our data also reveal a pattern of evolutionary convergence in domatia morphology, with tuft-form domatia more likely to evolve in dry temperate habitats and pit domatia more likely to evolve in wet tropical environments. We have shown climate-associated drivers of mite domatia evolution, demonstrating their utility and power as an evolutionarily replicated system for the study of plant defense mutualisms.
Glucose-independent human cytomegalovirus replication is supported by metabolites that feed upper glycolytic branches
Authors: Mokry Rebekah L. , Purdy John G.
Published: November 2024

Viruses with broad tissue distribution and cell tropism successfully replicate in various nutrient environments in the body. Several viruses reprogram metabolism for viral replication. However, many studies focus on metabolic reprogramming in nutrient-rich conditions that do not recapitulate physiological environments in the body. Here, we investigated how viruses may replicate when a metabolite thought to be essential for replication is limited. We use human cytomegalovirus infection in glucose-free conditions as a model to determine how glucose supports virus replication and how physiologically relevant nutrients contribute to glucose-independent virus production. We find that glucose supports viral genome synthesis, viral protein production and glycosylation, and infectious virus production. Notably, supplement of glucose-free cultures with uridine, ribose, or UDP-GlcNAc—metabolites that feed upper glycolytic branches like the pentose phosphate pathway—results in partially restored virus replication, including low levels of infectious virus production. Supplementing lower glycolysis in glucose-free cultures using pyruvate fails to restore virus replication. These results indicate that nutrients can compensate for glucose via feeding upper glycolytic branches to sustain low levels of virus production. More broadly, our findings suggest that viruses may successfully replicate in diverse metabolic niches, including those in the body with low glucose levels, through alternative nutrient usage.
An E2 ubiquitin-conjugating enzyme links diubiquitinated H2B to H3K27M oncohistone function
Authors: Jiao Alan L. , Sendinc Erdem , Zee Barry M. , Wallner Felice , Shi Yang
Published: November 2024

The H3K27M oncogenic histone (oncohistone) mutation drives ~80% of incurable childhood brain tumors known as diffuse midline gliomas (DMGs). The major molecular feature of H3K27M mutant DMGs is a global loss of H3K27 trimethylation (H3K27me3), a phenotype conserved inCaenorhabditis elegans(C. elegans). Here, we perform unbiased genome-wide suppressor screens inC. elegansexpressing H3K27M and isolate 20 suppressors, all of which at least partially restore H3K27me3. 19/20 suppressor mutations map to the same histone H3.3 gene in which the K27M mutation was originally introduced. Most of these create single amino acid substitutions between residues R26-Y54, which do not disrupt oncohistone expression. Rather, they are predicted to impair interactions with the Polycomb Repressive Complex 2 (PRC2) and are functionally conserved in human cells. Further, we mapped a single extragenic H3K27M suppressor toubc-20, an E2 ubiquitin-conjugating enzyme, whose loss rescued H3K27me3 to nearly 50% wild-type levels despite continued oncohistone expression and chromatin incorporation. We demonstrate thatubc-20is the major enzyme responsible for generating diubiquitinated histone H2B. Our study provides in vivo support for existing models of PRC2 inhibition via direct oncohistone contact and suggests that the effects of H3K27M may be modulated by H2B ubiquitination.
Demystifying the English bias in science
Authors: Thomas Enlli Môn , Parry Nia Mererid , Caulfield Gareth , Siôn Cadi Gwen
Published: November 2024

Whilst the prevalence of English in STEM-related fields is well established, less is understood about the
opportunities to study these subjects in languages other than English. This study examined pupils’ likelihood of studying
STEM-related subjects in Welsh-medium secondary schools in Wales, their linguistic choices around these subjects and their
attitudes towards learning such subjects in English and/or in Welsh. The results revealed a general impression among pupils of the
importance of English for STEM, which, mediated by their own linguistic backgrounds, abilities and experiences, influenced pupils’
linguistic choices and desires. Since the propensity towards monolingual engagement with these subjects — in Welsh or in English —
may limit the scope for scaffolding their learning across languages and the benefits that incur, we propose alternative bilingual
approaches to STEM-related subject teaching.