bluuebunny/crossref_metadata_2025 huggingface dataset:
Spectral markers and morphological features of diabetic foot ulcer tissues
Authors: Isokov T. D. , Yanitskaya L. V. , Kovalenko Y. V. , Verevka S. V. , Labudzynskyi D. O. , Pasichna E. P. , Voitsitskyi T. V. , Gnatyuk O. P. , Dovbeshko G. I.
Published: February 2025

Metabolic disorders are an integral part of the development of diabetes mellitus. One of the most severe complications of diabetes is a diabetic foot, which is characterized by the formation of necrotic sores. The aim of the study was to experimentally test the hypothesis of the formation and accumulation of β-structured protein aggregates in diabetic foot tissues as markers of diabetes associated disorders. The formation of β-structured protein aggregates promotes their non-enzymatic glycosylation, which in turn promotes aggregation. There is a positive connection between the individual links of the pathological process. Breaking this link is a prerequisite for effective treatment. The results of the optical image analysis indicate the presence of β-structured protein aggregates, confirmed by IR spectroscopy. Thus, the presence of the total β-conformation reaches 47,6%. The assumption of an increasing contribution from the β-antiparallel conformation was made. Clear IR markers of necrotic tissues in the absorption region of stretching vibrations of C ˭ O and C–O molecular groups as well as a 2.5-fold increase in the intensity of the CH stretching bands compared to OH were observed. Conformational fitting and correlation analysis between different protein phases showed that the necrosis spectroscopic feature strongly correlates with water content, and α-helix plus triple helix negatively correlate with water content, β-conformation, and necrosis features. The assumption of an increasing contribution from β-antiparallel conformation connected with amyloid-like fibril formation was done.
Non-equilibrium states and interactions in the topological insulator and topological crystalline insulator phases of NaCd4As3
Authors: Kafle Tika R , Zhang Yingchao , Wang Yi-yan , Shi Xun , Li Na , Sapkota Richa , Thurston Jeremy , You Wenjing , Gao Shunye , Dong Qingxin , Rossnagel Kai , Chen Gen-Fu , Freericks James , Kapteyn Henry C , Murnane Margaret M
Published: February 2025

Topological materials are of great interest because they can support metallic edge or surface states that are robust against perturbations, with the potential for technological applications. Here, we experimentally explore the light-induced non-equilibrium properties of two distinct topological phases in NaCd4As3: a topological crystalline insulator (TCI) phase and a topological insulator (TI) phase. This material has surface states that are protected by mirror symmetry in the TCI phase at room temperature, while it undergoes a structural phase transition to a TI phase below 200 K. After exciting the TI phase by an ultrafast laser pulse, we observe a leading band edge shift of >150 meV that slowly builds up and reaches a maximum after ∼0.6 ps and that persists for ∼8 ps. The slow rise time of the excited electron population and electron temperature suggests that the electronic and structural orders are strongly coupled in this TI phase. It also suggests that the directly excited electronic states and the probed electronic states are weakly coupled. Both couplings are likely due to a partial relaxation of the lattice distortion, which is known to be associated with the TI phase. In contrast, no distinct excited state is observed in the TCI phase immediately or after photoexcitation, which we attribute to the low density of states and phase space available near the Fermi level. Our results show how ultrafast laser excitation can reveal the distinct excited states and interactions in phase-rich topological materials.
Incorporating memory into propagation of 1-electron reduced density matrices
Authors: Bhat Harish S. , Bassi Hardeep , Ranka Karnamohit , Isborn Christine M.
Published: February 2025

For any linear system with unreduced dynamics governed by invertible propagators, we derive a closed, time-delayed, linear system for a reduced-dimensional quantity of interest. This method does not target dimensionality reduction: rather, this method helps shed light on the memory-dependence of 1-electron reduced density matrices in time-dependent configuration interaction (TDCI), a scheme to solve for the correlated dynamics of electrons in molecules. Though time-dependent density functional theory has established that the 1-electron reduced density possesses memory-dependence, the precise nature of this memory-dependence has not been understood. We derive a symmetry/constraint-preserving method to propagate reduced TDCI electron density matrices. In numerical tests on two model systems (H2 and HeH+), we show that with sufficiently large time-delay (or memory-dependence), our method propagates reduced TDCI density matrices with high quantitative accuracy. We study the dependence of our results on time step and basis set. To implement our method, we derive the 4-index tensor that relates reduced and full TDCI density matrices. Our derivation applies to any TDCI system, regardless of basis set, number of electrons, or choice of Slater determinants in the wave function.
Analytic calculation of transition dipole moment using four-component relativistic equation-of-motion coupled-cluster expectation value approach
Authors: Mukhopadhyay Tamoghna , Chakraborty Sudipta , Chamoli Somesh , Nayak Malaya K. , Dutta Achintya Kumar
Published: February 2025

We have developed an efficient scheme for the calculation of transition properties within the four-component relativistic equation-of-motion coupled cluster (EOM-CC) method using the expectation value approach. The calculation of transition properties within the relativistic EOM-CC framework requires the solution of both right and left eigenvectors. The accuracy of the approach has been investigated by calculating low-lying transitions of a Xe atom, a HI molecule, and spin forbidden 1S0 → 3P1 and spin allowed 1S0 → 1P1 transitions in a few closed shell cations. In addition to the valence spectra, the relativistic EOM-CCSD expectation value approach is particularly suitable for simulating the L-edge x-ray absorption spectrum (XAS). The calculated results show good agreement with the earlier reported theoretical studies and experimental values.
Density matrices and entropy operator for non-Hermitian quantum mechanics
Authors: Bagarello F. , Gargano F. , Saluto L.
Published: February 2025

In this paper we consider density matrices operator related to non-Hermitian Hamiltonians. In particular, we analyze two natural extensions of what is usually called a density matrix operator (DM), of pure states and of the entropy operator: we first consider those operators which are simply similar to a standard DM, and then we discuss those which are intertwined with a DM by a third, non invertible, operator, giving rise to what we call Riesz Density Matrix operator (RDM). After introducing the mathematical framework, we apply the framework to a couple of applications. The first application is related to a non-Hermitian Hamiltonian describing gain and loss phenomena, widely considered in the context of PT-quantum mechanics. The second application is related to a finite-dimensional version of the Swanson Hamiltonian, never considered before, and addresses the problem of deriving a milder version of the RDM when exceptional points form in the system.
Control of wave processes in systems of active Brownian particles in gas-discharge plasma
Authors: Svetlov A. S. , Trukhachev F. M. , Kononov E. A. , Vasiliev M. M. , Petrov O. F.
Published: February 2025

The influence of laser-induced active Brownian motion on dust-acoustic instability in the colloidal plasma of a direct current glow discharge was experimentally studied. The dust structure was formed by spherical monodisperse melamine-formaldehyde particles with a partial copper coating (Janus particles). It is shown that with increasing laser radiation intensity, a self-excited plane dust-acoustic wave decays. At an intensity of ≈1.5 W/cm2, the wave ceases to be observed in a three-dimensional plasma–dust cloud. As the intensity decreases, the wave is excited again, which indicates the reversibility of the process. The results obtained can be used to control collective plasma processes.
Complex thermoelectric transport in Bi-Sb alloys
Authors: Orenstein Rachel , Ciesielski Kamil , Synoradzki Karol , Qu Jiaxing , Bipasha Ferdaushi Alam , Gomes Lídia C. , Adamczyk Jesse M. , Berger Shannon , Ertekin Elif , Toberer Eric S.
Published: February 2025

Bi1−xSbx alloys are classic thermoelectric materials for near-cryogenic applications. Despite more than half a century of study, unraveling the underlying transport physics within this space has been nontrivial due to the complex electronic structure, disorder, and small bandgap within these alloys. Furthermore, as Peltier coolers, Bi1−xSbx alloys operate in a bipolar regime; as such, understanding the impact of minority carriers is critical for further improvements in device performance. This study unites first principles calculations with low-temperature experimental measurements to create a generalized model for transport within semiconducting Bi-Sb alloys. Our exploration reveals the interplay between the complex, degenerate valence band structure with the extremely light conduction bands. By building a hybrid computational/experimental model, an understanding of both the electron and hole relaxation times emerges both as a function of temperature and energy. Special quasi-random supercell calculations reveal that, despite significant atomic disorder, the electronic band structures within the alloy remains largely unaffected and electron–phonon scattering dominates. For charge carriers near the band edges, the relaxation times are thus extremely long, consistent with cyclotronic behavior appearing at low magnetic fields (≪ 1 T). Modeling thermoelectric performance suggests that the valence band edge deformation potential is significantly weaker and highlights the potential for p-type compositions to meet or exceed the current n-type alloys.
Electrically tunable metal–semiconductor behavior in 2H-MoTe2
Authors: Manoj Kumar B. , Gaonkar Shreya , H. Lone Rashed , Malavika C. , Kannan E. S.
Published: February 2025

In this study, we report tunable metallic and semiconducting behavior in molybdenum di-telluride (2H-MoTe2) by manipulating the Joule heating process through electrical control of the channel current. At low voltages, 2H-MoTe2 exhibits semiconducting behavior. As the current surpasses a critical threshold at higher voltages, the material transitions to a metallic-like state, confirmed by a positive temperature coefficient of resistance. Temperature- and voltage-dependent Raman studies confirm that this semiconducting to metal-like transition occurs without any accompanying structural phase transformation. This metallic behavior is likely due to enhanced phonon scattering caused by the increase in lattice temperature. In the metallic state, exposure to H2 gas results in a negative response, with increased resistance due to additional phonon scattering. Conversely, laser exposure at this state produces no noticeable photoresponse because the already high lattice temperature limits the impact of further heating. These effects were suppressed when 2H-MoTe2 was placed on a hexagonal boron nitride/multilayer graphene heat sink. This dynamic modulation of conductivity in 2H-MoTe2 through electrical stimuli highlights its potential for nanoelectronic device applications.
Tuning chiral edge state and spin-filtering in irradiated silicene nanoribbons based on side potentials
Authors: Yang Jia-En , Long Jia-Xuan , Lü Xiao-Long
Published: February 2025

Topological edge states are critical for developing low-loss devices, making it essential to understand their properties. This study examines the influence of side potentials on the topological edge states in irradiated zigzag silicene nanoribbons. The potentials consist of three external fields, which collectively facilitate the emergence of modified chiral edge modes and spin-valley-related chiral edge states. The mechanism involves shifting the spin-polarized edge states outside the range of the Fermi level with the side potentials, thereby inducing intriguing topological edge states. Additionally, we propose a quasi-bulk state characterized by exponential decay that differs from conventional bulk modes. Based on these modified edge states, a tunable spin filter utilizing side potentials is proposed. We believe that these findings are essential for future developments in spintronic device design.
Nonlinear bias of collective oscillation frequency induced by asymmetric Cauchy noise
Authors: Ageeva Maria V. , Goldobin Denis S.
Published: February 2025

We report the effect of nonlinear bias of the frequency of collective oscillations of sin-coupled phase oscillators subject to individual asymmetric Cauchy noises. The noise asymmetry makes the Ott–Antonsen ansatz inapplicable. We argue that, for all stable non-Gaussian noises, the tail asymmetry is not only possible (in addition to the trivial shift of the distribution median) but also generic in many physical and biophysical setups. For the theoretical description of the effect, we develop a mathematical formalism based on the circular cumulants. The derivation of rigorous asymptotic results can be performed on this basis but seems infeasible in traditional terms of the circular moments (the Kuramoto–Daido order parameters). The effect of the entrainment of individual oscillator frequencies by the global oscillations is also reported in detail. The accuracy of theoretical results based on the low-dimensional circular cumulant reductions is validated with the high-accuracy “exact” solutions calculated with the continued fraction method.
Theoretical study of mode competition including backward wave and experiment on the 28 GHz second harmonic gyrotron
Authors: Jia Kai , Niu Xinjian , Liu Yinghui , Liu Jianwei , Sun Zongzheng , Li Hongfu
Published: February 2025

The gyrotron operates in the harmonic state, which can significantly reduce the required operating magnetic field but complicates the mode competition problem. In some situations, it is also possible for the backward wave of the fundamental wave mode to be excited to suppress the desired harmonic operating mode. Therefore, a detailed analysis of mode competition is necessary for gyrotrons operating in the harmonic state. This paper presents the theoretical research of mode competition and experimental work for the 28 GHz second harmonic gyrotron at the TE02 mode. Possible mode competition problems are analyzed in detail using the linear theory and the multimode time-dependent non-linear theory. The problem of excitation of the backward wave of the fundamental wave mode TE21, which may be present, is received focused investigation. Ultimately, the possible competition modes are successfully suppressed in the non-linear simulation by setting up a suitable startup scenario, and an interaction efficiency of 32.5% is obtained. Based on the theoretical research results, experimental verification is carried out. When the working voltage is 29.8 kV, the beam current is 1.18 A, and we obtain stable single mode operation of the gyrotron, which has an operation frequency of about 27.96 GHz and an interaction efficiency of about 30.1% from the experiment.
Two optimization problems for the Loewner energy
Authors: Wang Yilin
Published: February 2025

A Jordan curve on the Riemann sphere can be encoded by its conformal welding, a circle homeomorphism. The Loewner energy measures how far a Jordan curve is away from being a circle, or equivalently, how far its welding homeomorphism is away from being a Möbius transformation. We consider two optimizing problems for the Loewner energy, one under the constraint for the curves to pass through n given points on the Riemann sphere, which is the conformal boundary of hyperbolic 3-space H3; the other under the constraint for n given points on the circle to be welded to another n given points of the circle. The latter problem can be viewed as optimizing positive curves on the boundary of AdS3 space passing through n prescribed points. We observe that the answers to the two problems exhibit interesting symmetries: optimizing the Jordan curve in ∂∞H3 gives rise to a welding homeomorphism that is the boundary of a pleated plane in AdS3, whereas optimizing the positive curve in ∂∞ AdS3 gives rise to a Jordan curve that is the boundary of a pleated plane in H3.
Combined molecular and spin dynamics simulation of BCC iron with vacancy defects
Authors: Mudrick Mark , Eisenbach Markus , Perera Dilina , Landau David P.
Published: February 2025

Utilizing an atomistic computational model, which handles both translational and spin degrees of freedom, combined molecular and spin dynamics simulations have been performed to investigate the effect of vacancy defects on spin wave excitations in ferromagnetic iron. Fourier transforms of space- and time-displaced correlation functions yield the dynamic structure factor, providing characteristic frequencies and lifetimes of the spin wave modes. A comparison of the system with a 5% vacancy concentration with pure lattice data shows a decrease in frequency and a decrease in lifetime for all transverse spin wave excitations observed. In addition, the clearly defined transverse spin wave excitations are distorted with the introduction of vacancy defects, and we observe reduced excitation lifetimes due to increased magnon–magnon scattering. We observe further evidence of increased magnon–magnon scattering, as the peaks in the longitudinal spin wave spectrum become less distinct. Similar impacts are observed in the vibrational subsystem, with a decrease in characteristic phonon frequency and flattening of lattice excitation signals due to vacancy defects.
A theoretical and computational model for the synergy of electrostriction and photovoltaic effect to create photostriction
Authors: Singh Diwakar , Sharma Saurav , Kumar Rajeev , Vaish Rahul , Chauhan Vishal Singh
Published: February 2025

The phenomenon of photostriction, which involves generating mechanical actuation in response to light, is observed in a very limited number of materials from ferroelectric, semiconductors, and organic material classes. This limited choice of materials, combined with their responsiveness to narrow light spectra, has constrained the broader adoption of photostriction in practical applications. This study introduces a novel approach by integrating photovoltaic and electrostrictive couplings in composites made of a photovoltaic matrix with ferroelectric inclusions, yielding an apparent photostrictive effect. By leveraging the simultaneous action of both photovoltaic and electrostrictive effects, the composite efficiently converts irradiated optical energy into mechanical energy, enabling mechanical actuation across a broader range of materials and light spectra. First, we develop a computational framework for intertwined multiphysics coupling of the photovoltaic effect with nonlinear electrostriction, based on a novel constitutive model. Then, to evaluate all the effective properties that define the composite's behavior, we introduce a multiphysics-coupled homogenization framework capable of computing elastic, electrostrictive, dielectric, and thermal properties. Finally, a shell finite element formulation based on the assumptions of first-order shear deformation theory is used to analyze the behavior of the homogenized photo-electrostrictive composite based actuator. This study demonstrates the feasibility of the proposed composite by examining the deflection response of structures laminated with this photostrictive composite. Several case studies are conducted to provide insights into the development and characterization of photo-electrostrictive composites, which hold great potential for applications in mechanical actuation, shape morphing, and beyond.
Simulation of electron and nuclear spin dynamics in many-spin charge-separated states
Authors: Zhukov Ivan , Fishman Natalya , Lukzen Nikita , Klein Johannes , Steiner Ulrich E. , Lambert Christoph , Yurkovskaya Alexandra
Published: February 2025

This study presents a numerical simulation approach to investigate singlet–triplet interconversion effects in organic materials with rigid molecular structures that facilitate the photogeneration of charge-separated (CS) states, such as zwitterions resulting from intramolecular electron transfer. Our approach enables the detailed modeling of electron and nuclear spin-dependent observables, including magnetic field-affected reaction yields (MARY) and chemically induced dynamic nuclear polarization (CIDNP). The equilibrium solution of the stochastic Liouville equation can be obtained with simple algebraic manipulation by noting the relationship between the Laplace transform of the density operator and the time-domain representation of the same operator. Experimental MARY and CIDNP data are modeled as functions of key external and internal system parameters, such as magnetic field strength, hyperfine interactions, and exchange couplings. This allows for exploring processes that are otherwise experimentally inaccessible, providing deeper insights into the spin dynamics of the photoinduced CS state. Understanding these interconversion processes is not only essential for the fundamental photochemistry studies but also for the rational design and development of novel organic materials for photovoltaics and photocatalysis. Our results demonstrate the significant impact of singlet–triplet interconversion on the overall efficiency of charge separation and recombination processes, highlighting the importance of spin dynamics in the design of next-generation organic photovoltaic materials.
FPGA-based process, voltage, and temperature insensitive picosecond resolution timing generators with offset correction for automatic test equipment
Authors: Guo Zeyu , Gui Liangqi , Sheng Kai
Published: February 2025

This paper presents the implementation of a picosecond resolution timing generator (TG) insensitive to process, voltage, and temperature (PVT) variations for automatic test equipment. The TG is implemented in field-programmable gate arrays (FPGAs) using two-stage time interpolation, which utilizes a multi-phase generator, IDELAY3, and carry-chain resources. To enhance the test rate, each channel of the proposed TG consists of four parallel operating edge generators. The TG performance will deteriorate severely without offset correction due to its sensitivity to PVT variations. To improve the adaptability of the TG, we design a robust offset canceler to ensure stable performance of the TG, resilient to PVT variations. With the proposed architecture and offset canceler, the PVT-insensitive TG achieves a time resolution of 5 ps and offers a maximum dynamic range of 10 s. It also shows improved worst case integral non-linearity ranging from −4.7 to +4.6 ps with the operating temperature continuously varying from 15 to 65 °C and voltage ranging from 0.95 to 1.01 V in FPGAs. The proposed TG can be implemented in the Ultrascale or Ultrascale+ FPGA platform.
Morphology reconstruction from experimental small-angle x-ray scattering patterns by physics-aware neural network
Authors: Zhao Chenhao , Sun Shenyang , Han Xueqing , Zhu Jianhe , Yu Wancheng , Li Liangbin
Published: February 2025

In this work, we developed a new methodology that can reconstruct the morphology from experimental small-angle x-ray scattering (SAXS) patterns directly without modeling by using a physics-aware neural network, SAXSNN. By incorporating the scattering physics of x rays into the network, SAXSNN could be trained to capture the complex mapping between the SAXS patterns in reciprocal space and the corresponding morphologies in real space in an unsupervised way. We demonstrated the performance of SAXSNN on the experimental SAXS patterns of semicrystalline and amorphous polymers, i.e., hard-elastic isotactic polypropylene (iPP) films and plasticized poly(vinyl butyral) (PVB). The morphologies reconstructed by SAXSNN are well consistent with our existing knowledge of the morphology of iPP films and PVB. The developed methodology here allows us to rapidly predict the morphologies for any given SAXS pattern without any in-prior phase information and, thus, provides an intuitive understanding of the microstructures of the measured samples. A real-time feedback of the morphologies of measured samples to SAXS beamline users at modern synchrotron radiation light sources will be feasible in the near future.
Transient 19F photo-CIDNP: A practical tool to distinguish intermediate radical species and determine isotropic hyperfine coupling constants of 19F nuclei
Authors: Schmidt Anton , Ayekoi Audrey , Illarionov Boris , Fischer Markus , Bacher Adelbert , Weber Stefan
Published: February 2025

Fluorine-containing flavin derivatives can be used as probes in flavin-binding proteins forming radical pairs to exploit the photo-chemically induced dynamic nuclear polarization (photo-CIDNP) effect. Knowledge of the hyperfine structure is crucial for studying the mechanism of intramolecular radical-pair formation in proteins. Transient 19F photo-CIDNP NMR has so far not been used to determine the isotropic hyperfine coupling constants of 19F nuclei. Here, we show that this method provides reliable results by studying three monofluorinated flavin mononucleotide (FMN) derivatives in conjunction with 6-fluoro-tryptophan. Combining this method with transient 1H photo-CIDNP spectroscopy leads to a more accurate interpretation of the intermediate radical species forming a radical pair. The gathered information can be used to identify the most promising FMN derivative for usage as a probe for formation of radical pairs in proteins.
An experimental study on the use of dielectric barrier discharge plasma actuators for electrospray dynamics enhancement
Authors: Moreira M. , Rodrigues F. , Páscoa J.
Published: February 2025

Electrospray technology, central to numerous scientific and industrial applications, utilizes electrostatic means to produce fine aerosol droplets, a process fundamentally characterized by the Taylor cone phenomenon. This research explores the integration of dielectric barrier discharge (DBD) plasma actuators to enhance the electrospray process. By generating ionic wind, the DBD plasma actuators influence droplet formation, control, and stability. The experimental setup involved precise control of electrospray parameters, visualization through high-speed cameras, and droplet characterization via phase Doppler anemometry (PDA). Results indicated that the ionic wind from plasma actuators reduced droplet size and enhanced spray uniformity, particularly in the multi-jet mode. The findings demonstrate the potential of plasma-assisted electrospray with an observed overall droplet diameter 13.9%–29.8% increase and a global droplet velocity 6.3%–7.1% increase, while also stabilizing the efficiency of the spray and reducing the measurement time. These improvements offer a fine tuning on the electrospray, which can be particularly useful in fields such as drug delivery and materials synthesis by offering enhanced control over droplet characteristics and electrospray dynamics.
Curvilinear self-propulsion of Leidenfrost droplets on an immiscible liquid layer with Bénard–Marangoni cells
Authors: Feng Lin , Qu Junlei , Chen Chen , Zhu Ji-Long , Shi Wan-Yuan
Published: February 2025

The motion of Leidenfrost droplet on a hot liquid surface poses attractive features in self-propelling drops, nanofabrication, and frictionless transport. Nonetheless, the Marangoni instability inside the heated liquid pool was ignored and its influence on the behavior of Leidenfrost droplets remains an open question. Here, we report a remarkable curvilinear self-propulsion of Leidenfrost droplets suspended on an immiscible liquid pool where the Marangoni instability arises. In a thin liquid pool, the motion of Leidenfrost droplets is not random, but rather definitely directs to the center of Bénard–Marangoni cells, across it and traveling toward surrounding cells. With the increase in pool thickness, the propulsion speed of droplet decreases gradually and eventually gets totally trapped among Rayleigh–Bénard–Marangoni cells. Combined with numerical simulations, we show that the curvilinear propulsion of Leidenfrost droplets is induced by the Marangoni effect of liquid pool, which consists of the pool surface fluctuation and the sustaining evaporative cooling effect of droplet on pool surface. Our findings provide deeper physical insights into the dynamics of a Leidenfrost droplet over a heated liquid pool and provide a potential approach of fluid transport in the Leidenfrost state by regulating the surface morphology of liquid pool.
High Reynolds number bulk effects induced by superhydrophobic surfaces
Authors: Serafini F. , Villani F. , Gallo M. , Gualtieri P. , Battista F.
Published: February 2025

Drag reduction induced by superhydrophobic surfaces made of streamwise grooves is investigated through direct numerical simulation of turbulent pipe flow. When the ratio between the groove width and the viscous length exceeds 50, most of the wall slippage effect is maintained in the bulk of the flow; thus, a large drag reduction is achieved. The effect is explained in terms of a modified mean and turbulent kinetic energy balance that accounts for the slippage effect at the wall. With typical groove sizes of technological devices, values of order 50 wall units can be achieved only at high friction Reynolds number, here increased up to Reτ≃2300.
Application of the entropy model to estimate flow discharge and bed load transport in a large river
Authors: Rezazadeh Shiva , Manafpour Mohammad , Bahmanpouri Farhad , Gualtieri Carlo
Published: February 2025

The amount of sediment bed load being carried by rivers significantly impacts the inherent development of the riverine systems in terms of hydrodynamic and morphodynamic changes. In this direction, acoustic Doppler current profiler velocity literature data collected at the Óbidos station in the Amazon River were applied to investigate bed-load transport using the Entropy method. First, the cross-sectional velocity distribution was estimated with that model for two scenarios of source data: (a) all surface velocities and (b) single surface velocity as the maximum surface velocity. The latter analysis was conducted with two different assumptions of the surface velocity distribution: parabolic and elliptic. The error percentage for estimation of the mean cross-sectional velocity and discharge was 2.08% based on considering all surface velocities and was 4.08% and 12.5% based on parabolic and elliptic scenarios, respectively. Next, the shear velocity and Shields mobility parameter were calculated for two scenarios. Finally, the dimensionless bed load transport rate was calculated based on a range of particle diameters. Applying the different equations for the dimensionless bed load transport rate based on various scenarios of surface velocity distributions, the results from the entropy method agreed with the experimental data in the literature. Overall, the current study highlighted the potential of the entropy model to estimate river discharge and bed load transport in large rivers relying only on surface velocity.
A coupled two-dimensional–three-dimensional hydrodynamic model for simulating flood wave evolution in reservoirs and riverbeds
Authors: Yuan Hao , Zou Yiyao , Diao Wei , Mao Yunfei
Published: February 2025

The geometric scale of real reservoirs is immense, and their boundaries are intricate. Consequently, two-dimensional numerical simulations of the entire reservoir cannot accurately capture the three-dimensional flow characteristics in localized regions. Conversely, comprehensive three-dimensional simulations are often unfeasible due to the substantial computational resources they demand. This paper proposes a two-dimensional-three-dimensional coupled hydrodynamic model by combining a two-dimensional shallow water model and a three-dimensional free surface model based on the Lattice Boltzmann Method. The model introduces algorithms that establish unified requirements for computational parameters, ensure the conservation of physical quantities at the interface, and facilitate the inversion of two-dimensional data to three-dimensional formats, as well as the integration of three-dimensional data into two-dimensional formats. The model was applied to meticulously simulate the evolution of flood waves resulting from dam breaches over uneven riverbeds. Through theoretical analysis and experimental comparisons, a detailed examination of the conservation and coherence of physical quantities at the interface was conducted, thereby validating the accuracy of the proposed approach. Finally, the large-scale evolution of wave surges in a riverbed hydropower station reservoir was simulated, effectively demonstrating the capability to address practical hydrodynamic challenges. Additionally, the discussion highlights the computational savings achieved by this model relative to conventional three-dimensional simulations, establishing a foundation for its application in real-world engineering cases.
Several compressible computational fluid dynamics methods applied to transient sheet/cloud cavitation
Authors: Yin Tingyun , Pavesi Giorgio
Published: February 2025

This paper introduces several compressible computational fluid dynamics (CFD) methods and assesses their ability to simulate typical sheet-to-cloud cavitating flow around a hydrofoil. More precisely, the Tait equation of state is used to describe the density of water, while the ideal gas equation of state is used to model the density of vapor. The first method assumes that the cavitation is a multiphase flow with isothermal conditions, meaning that it exhibits isothermal compressibility. Based on the first method, the second and third methods take into account the thermal energy and total energy equations, respectively, i.e., the thermal energy compressibility and the total energy compressibility. An incompressible simulation is also performed for the comparison. The results show that all of the strategies successfully replicate the periodic breakup of the sheet cavity and the formation of the cloud cavity. The predicted frequency of cavity shedding using compressible methods is higher than that using the incompressible method. In addition, all the CFD simulations confirm that the disturbance moving upward in the sheet cavity is actually a condensation shock. The overpressure resulting from the collapse of the cavity can be captured using three compressible approaches. The boundary layer and time-averaged hydrofoil pressure coefficient are compared and analyzed, revealing a negligible difference among the three compressible simulation results.
Double-pole solitons for the higher-order matrix nonlinear Schrödinger equation: Asymptotic analysis
Authors: Song Xiao-Meng , Du Zhong
Published: February 2025

In the paper, we focus on the double-pole solutions and their asymptotic behavior of the higher-order matrix nonlinear Schrödinger equation. In the case of zero background conditions, we derive the double-pole solutions, which can describe degenerate solitons and illustrate their dynamic behaviors. By means of three kinds of asymptotic balances, we derive the exact Sech-type expressions for all the asymptotic soliton branches of the double-pole solutions. Through a distance expression of two asymptotic solitons, we find that the distance between two asymptotic solitons logarithmically increases with the absolute value of the coefficient of higher-order dispersion and nonlinear terms. Furthermore, we also study such physical properties of asymptotic solitons as velocity and central trajectory line, and observe that the asymptotic soliton is basically consistent with the double-pole solutions. Based on the expressions of the velocities, we show that the velocity is negatively related to the absolute value of time variable. Our results in the paper may be helpful for investigating dynamical properties and interactions of other physical systems.
Effect of a vertical baffle on the resonant steady-state sloshing impacts in a square-base container with longitudinal harmonic excitations
Authors: Liu Dongxi , Zhang Xia , Wang Jin
Published: February 2025

Three-dimensional (3D) resonant liquid sloshing is experimentally investigated in a square-base container with and without a vertical baffle subjected to harmonic horizontal forcing. This study aims to understand the influence of baffle height on the sloshing response, including viscous damping, natural frequency, frequency ranges of different wave modes, wave profiles, and impact pressures on the sidewall and roof. A relatively large liquid depth and three different vertical baffles with varying heights are considered. To elucidate the experimental observations, a potential-based analytical solution for natural sloshing modes and an asymptotic modal system for the frequency ranges of wave modes are employed. Theoretically, four types of sloshing wave modes exist, i.e., planar standing, diagonal standing, regular rotating, and irregular chaotic wave modes, for a clean container. However, diagonal standing waves are difficult to experimentally observe because their effective frequency domain coincides then with those for the planar ones. Therefore, the other three wave modes are focused on herein. When the amplitude of the rotating and chaotic waves is large, the corner of the roof experiences extremely high impact pressures. Consequently, the frequency ranges of rotating and chaotic waves evidently decrease with increasing baffle height. Furthermore, the sloshing wave amplitude and maximum impact pressure at the roof decreases due to the suppression effects of the baffle.
Rotation of spheroidal tracer particles in spanwise rotating channel turbulence
Authors: Chen Dongming , Cui Zhiwen , Yuan Wenjun , Zhao Lihao , Andersson Helge I.
Published: February 2025

This Letter focuses on rotational motion of spheroids and is a sequel to our recent investigation on particle orientations in rotating channel flow [Chen et al., “Orientation of inertialess spheroidal particles in turbulent channel flow with spanwise rotation,” J. Fluid Mech. 998, A44 (2024)]. As the channel rotation Ro increases, the mean particle rotation on the suction side decreases monotonically, while on the pressure side, it continuously increases. Increasing and decreasing rates of disks tumbling and rods spinning with increasing Ro were found at the pressure and suction sides, respectively. These findings are likely due to the damping and augmentation of the vorticity fluctuations at the suction and pressure sides caused by the imposed system rotation.
From rediscovery towards recovery: a recent history of Australia’s most critically endangered marsupial, Gilbert’s potoroo (Potorous gilbertii)
Authors: Friend J. Anthony , Sinclair Elizabeth A. , Courtenay Jacqueline M.
Published: February 2025

Context Ngilgaitch/Gilbert’s potoroo (Potorous gilbertii) was presumed extinct until its rediscovery at Two Peoples Bay Nature Reserve, Australia, in 1994. Aims Our paper summarises the history and rediscovery of Ngilgaitch/Gilbert’s potoroo, outlines the diverse research conducted to inform recovery, describes key management actions, and documents the fluctuating fortunes of the species between 1994 and 2024. Methods We summarise research and management actions to promote the species’ recovery at Two Peoples Bay Nature Reserve and nearby reserves. Key results About 40 Ngilgaitch/Gilbert’s potoroo survived in heathland on the slopes of Maardjitup Gurlin/Mount Gardner, feeding almost exclusively on the fruiting bodies of hypogeal fungi. Two ‘insurance’ populations were established between 2005 and 2014 by translocation from the original population to Bald Island (810 ha) and a mainland enclosure (380 ha). These colonies proved critical to the species’ survival when a wildfire consumed most of the habitat at Two Peoples Bay in November 2015, causing the functional extinction of the population. Efforts have begun to restore this population through translocation from the insurance populations. Conclusion Establishing new potoroo populations by translocation has been the most valuable recovery technique for this species. Current and predicted climate change must be considered when choosing translocation sites. Management of all populations requires effective fire management, feral predator control, and actions derived from genetic information. Implications The Two Peoples Bay potoroo population was effectively lost following the 2015 fire. However, the regenerating habitat at the site remains an important resource in efforts to ensure the survival of the species.
Synergistic anion–π interactions in peptidomimetic polyethers
Authors: Lee Seunghyun , Shin Aram , Park Jinwoo , Yun Sowon , Kim Minseong , Lee Dong Woog , Kim Byeong-Su
Published: February 2025

Anion–π interactions are crucial in various biological processes, such as enzyme catalysis and ion transport. Despite their significance, the exploitation of anion–π interactions in synthetic polymer systems remains underexplored. This study investigates anion–π interactions using chemically well-defined peptidomimetics guided by the composition of mussel foot proteins. Specifically, polyether-based polymers were designed utilizing two functional epoxide monomers—catechol acetonide glycidyl ether and 4,4-dimethyl-2-oxazoline glycidyl ether—to mimic the key amino acids 3,4-dihydroxyphenylalanine and aspartic acid, respectively. A surface forces apparatus was employed to study the anion–π interaction between the polymers, considering the effects of relative monomer composition and pH conditions. The maximum cohesion energy of 15.0 mJ/m
2
was observed at an equimolar monomer composition at pH 7. Incorporating a phenyl group instead of the catechol group and introducing competing anions confirmed the dominant role of anion–π interactions. This study highlights the significance of anion–π interactions, posing a high potential in the design and synthesis of functional materials.
Quantum state tomography on closed timelike curves using weak measurements
Authors: Bishop Lachlan G , Costa Fabio , Ralph Timothy C
Published: February 2025

Any given prescription of quantum time travel necessarily endows a Hilbert space to the chronology-violating (CV) system on the closed timelike curve (CTC). However, under the two foremost models, Deutsch’s prescription (D-CTCs) and postselected teleportation (P-CTCs), the CV system is treated very differently: D-CTCs assign a definite form to the state on this system, while P-CTCs do not. To further explore this distinction, we present a methodology by which an operational notion of state may be assigned to their respective CV systems. This is accomplished via a conjunction of state tomography and weak measurements, with the latter being essential in leaving any notions of self-consistency intact. With this technique, we are able to verify the predictions of D-CTCs and, perhaps more significantly, operationally assign a state to the system on the P-CTC. We show that, for any given combination of chronology-respecting input and unitary interaction, it is always possible to recover the unique state on the P-CTC, and we provide a few specific examples in the context of select archetypal temporal paradoxes. We also demonstrate how this state may be derived from analysis of the P-CTC prescription itself, and we explore how it compares to its counterpart in the CV state predicted by D-CTCs.
Microlocal properties of the Radon transform on V-lines: a framework to reduce artifacts due to intrinsic missing data in linear Compton cameras
Authors: Rosenblatt Mariel , Morvidone Marcela , Cebeiro Javier
Published: February 2025

Microlocal Analysis constitutes a theoretical framework based on Fourier analysis and differential geometry that provides a precise characterization of singularities in image reconstruction in the context of the classical Radon transform theory. Accurate descriptions of artifacts together with strategies to mitigate them have been proposed since it was introduced. Artifacts due to missing data are presumably the most challenging problem addressed by microlocal analysis. Recent extensions of these analytical concepts to the field of transmission Compton tomography show the efficacy of this theoretical framework. Conversely, in the case of Compton cameras, an emission technique wherein the issue of missing data is an intrinsic problem, these ideas are still unexplored. In this work we introduce a Radon transform over double V-lines, presenting its key properties for deriving a filtered back-projection formula. This theoretical groundwork enables us to outline an initial methodology utilizing microlocal analysis to develop a framework aimed at mitigating the main artifacts produced by the limited size of detectors in linear Compton cameras.
Temperature-dependent investigation of polarisation doping in 330 nm ultraviolet light-emitting diodes
Authors: Milner P , Zubialevich V Z , Singh S M , Pampili P , Corbett B , Parbrook P J
Published: February 2025

Polarisation doping of

Al
x

Ga

1
−
x

N, through grading of x, has realised major improvements in p-type conductivity in ultraviolet (UV) light-emitting diodes (LEDs) compared to conventional impurity doping. However, the exact balance between the two doping regimes to achieve the best device performance is not clear, especially as a function of operating wavelength. In this work, 330 nm LEDs with varied p-doping approaches were characterised as a function of temperature: Mg doped only (reference); polarisation doped and Mg doped (co-doped); and polarisation doped only. At room temperature, the co-doped LED showed the highest electroluminescence (EL) intensity, with a similar operating voltage to the reference LED. The highest hole concentration, confirmed by Hall effect measurements, as well as improved injection efficiency revealed by simulations, are credited as the main reasons for EL improvement. A parasitic near-UV luminescence tail, analogous to the ‘blue luminescence’ in p-GaN, was observed in both the reference and co-doped LEDs, but was absent in the polarisation doped LED. The reference LED demonstrated the highest increase in operating voltage with decreasing temperature, while the LED with only polarisation doping showed a temperature-independent behaviour, demonstrating the benefits of a polarisation field-induced carrier concentration. Further optimisation of the compositional grading with concurrent Mg doping can potentially produce higher performance LEDs with cleaner spectra.
Predicting two-dimensional ferroelastic semiconductors LuX (X=N, P, As): negative Poisson’s ratio, high carrier mobility, and strong visible light absorption
Authors: Chen Zibo , Ma Fengxian , Gao Zhen , Jiao Yalong
Published: February 2025

Two-dimensional (2D) materials manifesting ferroelasticity have received significant attention, yet it is uncommon for single materials to exhibit ferroelasticity alongside high carrier mobilities and strong visible light absorption. In this study, we use first-principles calculations to predict three 2D semiconductors: LuX monolayers (X = N, P, As), which are distinguished by their exceptional dynamical, thermodynamic, and mechanical stability. These LuX monolayers feature band gaps ranging from 0.98 eV to 1.98 eV, placing them within the ideal range for solar cell applications, and they exhibit strong visible light absorption, reaching up to 5%. Notably, the LuP monolayer demonstrates remarkable carrier mobility, reaching 1796 cm2·s−1·V−1, surpassing that of MoS−1 and showcasing its superior transport properties. Mechanical analyses reveal a significant in-plane negative Poisson’s ratio (NPR) for these materials, as high as −0.37, which is substantially greater than that of black phosphorus. Additionally, all LuX monolayers are identified as 2D ferroelastic materials, with reversible strains ranging from 12.9% to 17.8%. Our findings highlight the exceptional electronic, mechanical, and optical properties of the LuX monolayers, making them promising candidates for a wide range of multifunctional applications.