bluuebunny/crossref_metadata_2025 huggingface dataset:
CHEOPS observations confirm nodal precession in the WASP-33 system
Authors: Smith A. M. S. , Csizmadia Sz. , Van Grootel V. , Lendl M. , Persson C. M. , Olofsson G. , Ehrenreich D. , Günther M. N. , Heitzmann A. , Barros S. C. C. , Bonfanti A. , Brandeker A. , Cabrera J. , Demangeon O. D. S. , Fossati L. , Harre J.-V. , Hooton M. J. , Hoyer S. , Kalman Sz. , Salmon S. , Sousa S. G. , Szabó Gy. M. , Wilson T. G. , Alibert Y. , Alonso R. , Asquier J. , Bárczy T. , Barrado D. , Baumjohann W. , Benz W. , Billot N. , Borsato L. , Broeg C. , Collier Cameron A. , Correia A. C. M. , Cubillos P. E. , Davies M. B. , Deleuil M. , Deline A. , Demory B.-O. , Derekas A. , Edwards B. , Egger J. A. , Erikson A. , Fortier A. , Fridlund M. , Gandolfi D. , Gazeas K. , Gillon M. , Güdel M. , Hasiba J. , Helling Ch. , Isaak K. G. , Kiss L. L. , Korth J. , Lam K. W. F. , Laskar J. , Lecavelier des Etangs A. , Magrin D. , Maxted P. F. L. , Merín B. , Mordasini C. , Nascimbeni V. , Ottensamer R. , Pagano I. , Pallé E. , Peter G. , Piazza D. , Piotto G. , Pollacco D. , Queloz D. , Ragazzoni R. , Rando N. , Rauer H. , Ribas I. , Santos N. C. , Scandariato G. , Ségransan D. , Simon A. E. , Stalport M. , Sulis S. , Udry S. , Ulmer-Moll S. , Venturini J. , Villaver E. , Viotto V. , Walter I. , Walton N. A. , Wolf S.
Published: December 2024

Aims. We aim to observe the transits and occultations of WASP-33 b, which orbits a rapidly rotating δ Scuti pulsator, with the goal of measuring the orbital obliquity via the gravity-darkening effect, and constraining the geometric albedo via the occultation depth.

Methods. We observed four transits and four occultations with CHEOPS, and employ a variety of techniques to remove the effects of the stellar pulsations from the light curves, as well as the usual CHEOPS systematic effects. We also performed a comprehensive analysis of low-resolution spectral and Gaia data to re-determine the stellar properties of WASP-33.

Results. We measure an orbital obliquity 111.3−0.7+0.2 degrees, which is consistent with previous measurements made via Doppler tomography. We also measure the planetary impact parameter, and confirm that this parameter is undergoing rapid secular evolution as a result of nodal precession of the planetary orbit. This precession allows us to determine the second-order fluid Love number of the star, which we find agrees well with the predictions of theoretical stellar models. We are unable to robustly measure a unique value of the occultation depth, and emphasise the need for long-baseline observations to better measure the pulsation periods.
Closed-loop supply chain decision making considering product design strategy under patent protection
Authors: Cao Xiaogang , Xiao Boning , Wen Hui
Published: December 2024

This paper combines product design and patent protection and construct a dynamic decision-making model consisting of a single original manufacturer and a single remanufacturer based on Stackelberg game. We study the impact of different product design strategies on remanufacturing decisions in the presence of patent protection and explore the influencing factors of the original manufacturer’s product design level. The results show that: (1) the original manufacturer’s product design level is negatively correlated with the coefficient of R&D cost impact and the coefficient of remanufacturing cost, and positively correlated with the coefficient of consumer utility impact; (2) the unit patent licensing fee is positively correlated with the coefficient of R&D cost impact and negatively correlated with the coefficient of remanufacturing cost and the coefficient of consumer utility impact; (3) under different product design strategies, product design strategies that consider both eco-orientation and remanufacturing-orientation are most conducive to the stable development of the closed-loop supply chain.
A modified conjugate gradient method for unconstrained optimization with application in regression function
Authors: Guefassa Imane , Chaib Yacine
Published: December 2024

Due to its rapid convergence rate and low memory requirements, the conjugate gradient (CG) scheme is a popular technique for solving unconstrained optimization problems. This paper introduces a modified conjugate gradient method, GICY. By utilizing the strong Wolfe line search (SWLS), we prove that GICY satisfies the sufficient descent condition at every iteration, guaranteeing significant progress towards the minimum. Additionally, we establish the global convergence of the proposed method. Extensive numerical computations demonstrate the success and promise of this new algorithm, particularly when applied to practical problems involving nonparametric regression functions.
Modern radiotherapy for breast cancer: Update and new developments
Authors: Meixner Eva , Debus Jürgen
Published: December 2024

The delivery of radiotherapy for breast cancer has evolved significantly over the years. The aim of this review is to highlight important developments and current concepts. Postoperative hypofractionated three-dimensional conformal or intensity-modulated photon radiotherapy continues to be the standard application after breast-conserving surgery to improve local control. New therapy techniques in deep inspiration breath hold or physical-biological advantages of proton beam therapy offer innovative therapy methods with regard to the protection of normal tissue and reduced cardiotoxicity. Ultra-hypofractionated therapy concepts and the integration of a simultaneous integrated boost in hypofractionated therapy concepts also enable the duration of treatment to be reduced to a few days or weeks. In low-risk constellations, the radiation volume may also be de-escalated to partial breast irradiation, and if life expectancy is severely restricted at the same time, the omission of postoperative radiotherapy might be critically discussed. The oncological benefit of an irradiation of the regional lymph node regions continues to be confirmed in locally advanced, node-positive carcinomas and further enables the omission of surgical axillary lymph node dissection with low morbidity in individualized therapy approaches.
Stimmt es eigentlich, dass man über die Ernährung die Darmflora und damit die chronische Entzündung bei JIA beeinflussen kann?
Authors: Budzinski Lisa , Chang Hyun-Dong , Kallinich Tilmann
Published: December 2024

Entzündungsprozesse über die Ernährung zu regulieren, birgt das attraktive Potenzial, medikamentöse Behandlungen zu unterstützen oder deren Reduktion zu ermöglichen, Entzündungsschübe zu unterbinden und die Familien der Betroffenen in die Behandlung zu integrieren. Dabei besteht derzeit vor allem die Chance, mittels der Ernährung die Darmflora der Patient*innen zu beeinflussen, im Fokus. Die Darmflora hat einen besonderen Einfluss auf die menschliche Gesundheit, da sie durch die ständige Interaktion mit dem Immunsystem im Darm Immunantworten mit formt. Eine nicht ausbalancierte Darmflora beeinträchtigt auch die Balance des Immunsystems und ist damit potenziell an dysregulierten Immunantworten, so wie sie bei der JIA vorkommen, beteiligt. Dass die Ernährung ein potenzieller Ansatz zur Modulation der Darmflora mit positivem Effekt auf die Symptomatik der JIA ist, erläutern wir anhand einiger Studien für JIA und Beispielen aus der rheumatoiden Arthritis. Die gefundenen Mechanismen hinter dem entzündungshemmenden Effekt unterschiedlicher Ernährungskonzepte sind vielfältig, involvieren verschiedene Immunzellen und Stoffwechselprodukte, aber sind vor allem von der Individualität der Patient*innen und deren Darmflora geprägt. Damit ergibt sich bezüglich der Ernährungsempfehlungen wenig Konkretes, aber dafür durch zukünftig gezieltes Einbeziehen der Darmflora in JIA-Studien die Chance auf personalisierte Therapieunterstützung.
A Single-Center Pilot Study of Therapeutic Apheresis in Patients with
Severe Post-COVID Syndrome
Authors: Korth Johannes , Steenblock Charlotte , Walther Romy , Barbir Mahmoud , Husung Michael , Velthof Ansgar
Published: December 2024

After the COVID-19 pandemic, many patients have reported chronic fatigue and
severe post-exertional malaise, with symptoms similar to those of myalgic
encephalomyelitis/chronic fatigue syndrome (ME/CFS). The accumulation of
agonistic receptor autoantibodies targeting beta-adrenergic (β1 and β2) and
muscarinic (M3 and M4) neurotransmitter receptors may play a crucial role in the
pathomechanism of both ME/CFS and post-COVID conditions. Therapeutic apheresis
has been suggested as an effective treatment option for alleviating and
mitigating symptoms in this desperate group of patients. In this single-center
pilot study, we analyzed autoantibodies in a cohort of 20 post-COVID patients
before and after therapeutic apheresis. Apheresis resulted in a decline of β1 or
β2 adrenergic receptor antibodies in all patients. Additionally, the majority of
patients experienced a concurrent reduction in symptoms such as fatigue,
physical activity restrictions, myalgia, post-exertional malaise, and
concentration disorders. This study clearly demonstrates an association between
autoantibodies and the clinical improvement of post-COVID patients. Even if
future sham-controlled trials do not show a positive outcome, extracorporeal
apheresis may still be valuable for this patient group by temporarily improving
microperfusion and symptoms. Success in restoring patients to work and normal
life, as observed in many individuals after therapeutic apheresis, should be
recognized. Therefore, we believe that extracorporeal therapeutic apheresis, as
part of a multimodal treatment, should be considered an early intervention for
postinfectious syndromes in selected patients.
Anderson localization of circularly polarized waves in a gyrotropic superlattice with correlated disorder
Authors: Makarov N. M. , Pritula G. M. , Vekslerchik V. E. , Usatenko O. V. , Yampol’skii V. A.
Published: December 2024

In this paper, we explore the transmission of circularly polarized electromagnetic waves through one-dimensional random periodic-on-average photonic crystals containing layers of magneto-optical material in Faraday geometry. Driven by evidence that long-range correlations crucially influence wave localization within certain spectral ranges, our study aims to harness these effects for the development of novel electromagnetic wave filters tunable via a dc magnetic field. We base our study on a model of light propagation through a finite array of alternating dielectric layers with random thickness variations and layers of gyrotropic material of equal thickness. Assuming weak positional disorder, we employ analytical and numerical methods to analyze the inverse localization length and assess filter performance. Our results demonstrate that specific correlated disorder introduced into periodic systems can enhance or suppress the transmissivity for a wave of a given frequency in any desired interval of the magneto-optical parameter q. Additionally, we show that the Anderson localization can be resonantly suppressed when the thickness of each gyrotropic layer accommodates an integer number of half-wavelengths.
Shot noise as a diagnostic in the ν = 2/3 fractional quantum Hall edge zoo
Authors: Manna Sourav , Das Ankur , Gefen Yuval , Goldstein Moshe
Published: December 2024

The ν=2/3 filling is the simplest paradigmatic example of a fractional quantum Hall state, which contains counter-propagating edge modes. These modes can be either in the unequilibrated regime or equilibrated to different extents, on top of a possible edge reconstruction. In the unequilibrated regime, two distinct renormalization group fixed points have been previously proposed, namely Kane–Fischer–Polchinski and Wang–Meir–Gefen. In the equilibration regime, different degree of thermal equilibration may occur, while charge is fully equilibrated. Here, we show that this rich variety of models can give rise to three possible conductance plateaus at e2/2h (recently observed in experiments), 5e2/9h (predicted here), and e2/3h (observed earlier in experiments) in a quantum point contact geometry. We identify different mechanisms for electrical shot noise generation at these plateaus, which provides an experimentally accessible venue for distinguishing among the distinct models.
Spectral and thermodynamic properties of a particle in multiparameter exponential-type radial potential
Authors: Onate C. A. , Adedewe O. , Ikubanni S. O. , Olanrewaju D. B.
Published: December 2024

The solutions of the radial Schrödinger equation for a multiparameter potential of the exponential type are obtained using two traditional methods. The energy equation obtained was used to study both virial theorem and thermodynamic properties. The energy eigenvalues obtained for the potential and its subset potentials arecompletely bounded. The computed virial theorem depends on the parameters A, B, and V. The result also shows that the three parameters A, B, and V exhibit different features on the thermodynamic properties with V having the same variation for all the thermodynamic functions.
Unveiling the broadband optical properties of Bi2Te3: Ultrahigh refractive index and promising applications
Authors: Ermolaev Georgy A. , Vyslanko Ivan S. , El-Sayed Marwa A. , Tatmyshevskiy Mikhail K. , Slavich Aleksandr S. , Yakubovsky Dmitry I. , Eghbali Amir , Romanov Roman I. , Markeev Andrey M. , Kruglov Ivan A. , Novikov Sergey M. , Vyshnevyy Andrey A. , Arsenin Aleksey V. , Volkov Valentyn S.
Published: December 2024

van der Waals topological insulators, characterized by their high-index dielectric response, offer a promising materials platform for nanophotonics. Among these materials, Bi2Te3 has one of the highest refractive indices and extinction coefficients. However, the precise determination of Bi2Te3 optical properties remains challenging owing to its complicated physical model, which includes an oxide layer, topological conducting states, and optical anisotropy. Here, we resolve this problem and develop an accurate optical model for Bi2Te3 in a broad (450–1500 nm) spectral range. Our study shows that an oxide layer plays a major role in optical model for these wavelengths, while the influence of topological conducting states and optical anisotropy is minimal. Our model allows us to obtain accurate Bi2Te3 optical constants and demonstrate their use in biosensors, thermal theranostics, and topological phase singularities. Moreover, we observe a polarization transition of topological phase singularity for Bi2Se3, which opens a new direction for the development of topological phase effects. Therefore, our results open new avenues for photonic applications of Bi2Te3 optical properties.
Unifying the thermodynamic and electrostatic view on the pyroelectric effect
Authors: Arli Cihan , Atilgan Ali Rana , Misirlioglu I. Burc
Published: December 2024

Pyroelectricity is a first rank tensor (vector) property that connects electric displacement to temperature. Like all vector properties, it is allowed only in certain point group symmetries. In related literature, a number of formulations exist that apparently treat various contributions to the pyroelectric coefficient but without strictly considering the crystal symmetry. We revisit the formulation of the pyroelectric coefficient in the presence of external fields and find that a consistent treatment of the pyroelectric coefficient, allowing one to arrive at a single convergent formula starting from either thermodynamic or electrostatic arguments, may not be straightforward. Motivated by this outcome, we develop an approach allowing both electrostatic and thermodynamic arguments for pyroelectricity to converge to one single expression with mathematical consistency of the partial derivatives. Albeit not very significant at first sight, the approach and the manner in which fields are introduced prove vital in evaluating the field contributions to the pyroelectric effect and their deconvolution in experiments. Importance of the crystal point groups is also highlighted in the context of vector properties, specifically pyroelectric coefficient. Finally, the so-called induced pyroelectricity and a correct mathematical expansion of the polarization is discussed to clarify the contributions of the pyroelectric effect.
Ultrafast mid-infrared interferometric photocurrents in graphene-based two-terminal devices
Authors: Pettinger N. , Schmuck J. , Zhou X. , Loy S. , Zherebtsov S. , Kastl C. , Holleitner A. W.
Published: December 2024

We demonstrate that graphene-based two-terminal devices allow autocorrelating femtosecond mid-infrared pulses with a pulse duration of about 100 fs in the wavelength regime of 5.5–14 μm. The results suggest that the underlying ultrafast detection principle relies on an electric field dominated autocorrelation in combination with the optoelectronic dynamics at the metal–graphene interfaces. The demonstrated scheme excels because of the ease in nanofabrication of two-terminal graphene-based optoelectronic devices and their robustness.
Hamiltonian for complex plasmas
Authors: Ishihara Osamu
Published: December 2024

The Hamiltonian for a complex plasma involving dust spinning motion in a magnetic field is proposed. The formulation is in a classical limit of a quantum mechanical approach based on the Dirac equation, a relativistic wave equation in which the spin of particles is considered. The quantum mechanical spin term –γs·B [γ=gq/2m, g=2(Lande´ g−factor),q is a charge, m is a mass of a particle, and s = spin operator] is replaced by –γs·B [γ with g=1, s = I(ω+γB), I is the moment of inertia of a dust particle, and ω is the spinning angular velocity of a dust particle] in a classical limit. The wave–particle interaction involving spin motion is described as an interaction between particles and quasiparticles by the second quantization. The equation of motion with a damping term shows the relaxation of spinning dust particles aligning with the magnetic field.
A new fractal permeability model for the dual-porous medium with a bundle of rough tree-like fracture networks
Authors: Hu Bowen , Mi Xianzhen , Feng Xihui , Yu Liyuan , Su Haijian , Qiu Shikai , Shi Meixia , Zhang Tao , Li Wei , Xue Kangsheng
Published: December 2024

Shale gas reservoirs are typical dual-porous media where complex pore structures and fracture networks significantly impact gas transport. However, accurately predicting permeability in such media, especially complex fracture networks, remains challenging. The complex fracture network is modeled as of a bundle of rough tree-like fracture networks. The proposed permeability model comprehensively describes the structural characteristics of pores and fractures in shale gas reservoirs, including the fractal distribution of pore diameters and fracture apertures, the rough surface, and branching characteristics of fracture networks. Then, the model's accuracy is validated using reliable experimental permeability data. This model accurately predicts gas permeability and effectively describes gas transport characteristics in shale gas reservoirs with rough tree-like fracture networks. Each parameter has a clear physical meaning and avoids the use of empirical constants. Finally, sensitivity analyses are conducted to explore the effects of structural parameters on the permeability of dual-porous media. The results show that the permeability K of dual-porous media decreases exponentially with the increase in tortuosity fractal dimension Dtp of pores and surface fractal dimension Df of fractures, while it increases as a power function with increasing pore diameter fractal dimension Dp and fracture aperture fractal dimension Dh. The structural parameters of rough tree-like fracture networks significantly impact the permeability of dual-porous media. Increasing the aperture ratio γ, reducing the length ratio β, branching levels m, and the branching angles θ can significantly reduce gas flow resistance, decrease fluid kinetic energy loss, and increase the permeability of dual-porous media. This theoretical model is significant for enhancing permeability models of dual-porous media in shale gas reservoirs, offering reliable theoretical support for understanding gas migration and optimizing shale gas extraction.
A discretized representation for Monte Carlo simulation of deformed semiflexible chains
Authors: Tung Chi-Huan , Ding Lijie , Huang Guan-Rong , Wang Yangyang , Carrillo Jan-Michael Y. , Sumpter Bobby G. , Shinohara Yuya , Do Changwoo , Chen Wei-Ren
Published: December 2024

In this study, we present a novel orientation discretization approach based on the rhombic triacontahedron for Monte Carlo simulations of semiflexible polymer chains, aiming at enhancing structural analysis through rheo-small-angle scattering (rheo-SAS). Our approach provides a more accurate representation of the geometric features of semiflexible chains under deformation, surpassing the capabilities of traditional lattice structures. Validation against the Kratky–Porod chain system demonstrated superior consistency, underscoring its potential to significantly improve the precision of uncovering geometric details from rheo-SAS data. This approach opens new avenues for investigating the conformations of semiflexible polymers and mechanically induced phase transitions in more complex polymer structures, offering deeper insights into their behavior under various conditions.
Flow characterization of a submerged inclined impinging pulse jet
Authors: Mirikar Dnyanesh , Mishra Abhishek , Khan Majid Hassan , Agrawal Amit , Yadav Harekrishna
Published: December 2024

This study investigated flow characteristics associated with a circular pulse-impinging jet on an inclined surface using dye visualization and particle image velocimetry techniques. The experiments are carried out for various pulse frequencies (0.1 < St < 0.9) of the jet, a constant angle of surface inclination (θ  =  26°), and fixed surface spacing. The primary objective is to explore the flow dynamics aspect of pulse-inclined impinging jets with respect to the pulse frequency and Reynolds number. The present observation shows that at a certain degree of surface inclination (θ ≈ 28°), the jet momentum drives the entire flow in the downhill direction, which represents the critical angle of inclination. Furthermore, the critical angle of the inclination remains unchanged for both steady and pulse jets. The interaction of the inner and outer shear layers of the jet in the downhill direction highly depends on the pulse frequency, which is indeed triggered by the free jet vortices. In a free jet, the vortex formation and their growth depend on the jet shear layer response (convective acceleration) and the time available for vortex formation (local acceleration). Moreover, the instantaneous jet information reveals that the presence of the growing vortices increases the jet entrainment, and its movement along the surface enhances the mixing (shear stress) between the surrounding and boundary layer fluid. The results show that pulsation at Strouhal Number (St) = 0.44 help develop more coherent and durable vortices impinging on the surface, which is identical to the critical St for free and normal impinging jets. Pulsation near the critical St increases the jet entrainment and mixing between the inner and outer jet shear layers and is responsible for enhancement in the heat transfer rate. The results improve our understanding of heat transfer from pulse-inclined impinging jet and reinforce the existence of a critical St (= 0.44) with an inclined pulsing jet, providing the criteria for maximizing the heat transfer rate.
Experimental investigation on the relationships between hydrodynamic responses and output properties of flower-like triboelectric nanogenerator in a large wave-flow flume
Authors: Wu Zhiwen , Li Bo , Xie Canrong , Wan Lingyu , Garg Ankit , Liu Guanlin , Wen Honggui , Mei Guoxiong
Published: December 2024

Triboelectric nanogenerators (TENGs) have emerged as a promising technology for harvesting wave energy and converting it into electrical power. However, the practical application of TENGs in real-world ocean environments has been hindered by a lack of comprehensive data on their hydrodynamic responses and output properties under realistic wave-flow conditions. This gap in the literature has limited our understanding of how to optimize TENG designs for efficient wave energy conversion. In this study, a comprehensive series of experiments were conducted using a large wave-flow flume to investigate the performance of a flower-like TENG (FL-TENG) under various hydrodynamic conditions, including wave height, wave frequency, flow velocity, and structural geometry. The output voltage, motion responses, and cable tension of the FL-TENG were monitored using an electrometer, a machine vision-based displacement measurement system, and tensiometers, respectively. The results show that the relationship between the incident wave-flow area and the FL-TENG's output properties is more complex than a simple “bigger is better” trend. It is also found that the output voltage and hydrodynamic responses of the FL-TENG were positively correlated with the aspect ratio of the rectangular incident wave-flow shape. Importantly, the presence of water flow was observed to significantly inhibit the output properties and hydrodynamic responses of the FL-TENG. These findings provide valuable insights and new design considerations for advancing TENG applications in real-world ocean environments, ultimately contributing to the development of more efficient wave energy conversion technologies.
Tunable FSRS measurements with reduced background signals: Using an etalon filter to generate picosecond pump pulses in the 460–650 nm range
Authors: Lorenzo Emmaline R. , Karki Birendra , White Katie E. , Burns Kristen H. , Elles Christopher G.
Published: December 2024

Generating wavelength-tunable picosecond laser pulses from an ultrafast laser source is essential for femtosecond stimulated Raman scattering (FSRS) measurements. Etalon filters produce narrowband (picosecond) pulses with an asymmetric temporal profile that is ideal for stimulated resonance Raman excitation. However, direct spectral filtering of femtosecond laser pulses is typically limited to the laser’s fundamental and harmonic frequencies due to very low transmission of broad bandwidth pulses through an etalon. Here, we show that a single etalon filter (15 cm−1 bandwidth; 172 cm−1 free spectral range) provides an efficient and tunable option for generating Raman pump pulses over a wide range of wavelengths when used in combination with an optical parametric amplifier and a second harmonic generation (SHG) crystal that has an appropriate phase-matching bandwidth for partial spectral compression before the etalon. Tuning the SHG wavelength to match individual transmission lines of the etalon filter gives asymmetric picosecond pump pulses over a range of 460–650 nm. Importantly, the SHG crystal length determines the temporal rise time of the filtered pulse, which is an important property for reducing background and increasing Raman signals compared with symmetric pulses having the same total energy. We examine the wavelength-dependent trade-off between spectral narrowing via SHG and the asymmetric pulse shape after transmission through the etalon. This approach provides a relatively simple and efficient method to generate tunable pump pulses with the optimum temporal profile for resonance-enhanced FSRS measurements across the visible region of the spectrum.
Aerodynamic analysis of flattened pappus structures with linearly radial changes in filament diameter
Authors: Fu Lin-Tao , Fan Qing , Huang Zong-Liu , Chen Fei
Published: December 2024

Significant advances have been made in understanding the interaction between airflow and dandelion seed pappus models consisting of a central disk and tens of filaments. Previous theoretical analyses and numerical simulations assumed a radially constant filament diameter. However, experimental measurements revealed that the filament diameter could vary radially. The effect of radial variations in filament diameter on the interaction between airflow and dandelion seeds has not yet been explored. This piece of work, therefore, numerically investigated the flow patterns around five flattened pappus models with linearly radial changes in filament diameter and the aerodynamic forces acting on these models, across particle Reynolds numbers from 38 to 603. The vortex size, pressure coefficient and streamwise speed in the wake zones in the xoz plane (The z-axis coincides with the symmetry axis of the pappus structure.), the pressure coefficient, radial speed and streamwise speed in the xoy plane, the drag coefficient of the entire pappus model, and the aerodynamic force acting on a single filament were quantitatively analyzed and compared across the five models. It reveals that the radial change in filament diameter indeed results in the variations in these physical quantities among the five models. The variations can be significantly influenced by the particle Reynolds number, although these physical quantities exhibit different degrees of sensitivity. Our findings here will enhance the modeling of dandelion seed dispersal by wind and aid in optimizing the design of micro aircraft inspired by the architecture of real dandelion seed pappus structures.
Coaxial air-blast exfoliation breakup of a quasi-solid paste jet
Authors: Wang Yufan , Zhang Lihang , Zhao Hui , Liu Haifeng
Published: December 2024

A series of novel phenomena emerges when the coaxial airflow rapidly blows over the quasi-solid paste jet surface, leading to the direct solid-like exfoliation breakup of protrusions on the side face and the liquid-like tensile breakup on the end face. The experimental findings unequivocally demonstrate that the vertical protrusion formation on the side face under high gas velocity serves as a precursor to the subsequent exfoliation breakup, while the tensile breakup is a consequence of axial elongation of the protrusions at the junction between the side and end faces. A crucial step in interpreting the exfoliation breakup is to discern the individual force competition at the jet interface. As gas velocity increases, the radial shear force maintains stronger than the axial drag force and becomes the dominant factor. After the formation of protrusions, the airflow component directly impacts the upper surface of the protrusion in a vertical manner and causes it to fracture similar to the cutting off of a rod-shaped solid. During tensile breakup, the protrusions on the end face develop into liquid threads, which rotate and elongate under axial airflow drag and reflux, ultimately leading to the breakup. Mathematical force models are established to elucidate this intriguing phenomenon observed in the experiments. This study of quasi-solid pastes in airflow will expand the new understanding of the interaction between gas, liquid, and solid states.
Chromatin folding through nonuniform motorization by responsive motor proteins
Authors: Cao Zhiyu , Wolynes Peter G.
Published: December 2024

Chromatin is partially structured through the effects of biological motors. “Swimming motors” such as RNA polymerases and chromatin remodelers are thought to act differentially on the active parts of the genome and the stored inactive part. By systematically expanding the many-body master equation for chromosomes driven by swimming motors, we show that this nonuniform aspect of motorization leads to heterogeneously folded conformations, thereby contributing to chromosome compartmentalization.
Insights into multi-scale structural evolution and dielectric response of poly(methyl acrylate) under pre-strain: A simulation study
Authors: Qin Han , Liu Tao , Liu Zhaoyuan , Guo Meng , Guo Ying , Tian Ming
Published: December 2024

The structural evolution of dielectric elastomer induced by pre-strain is a complex, multi-scale process that poses a significant challenge to a deep understanding of the effect of pre-strain. Through simulation results, we identify the variation in the dielectric constant and multi-scale (electronic structure, molecular chain conformation, and aggregation structure) response of poly(methyl acrylate). As the pre-strain increases, the dielectric constant initially rises (below 200% pre-strain) and then declines (above 200% pre-strain). Analysis of the charge distribution, surface electrostatic potential, HOMO–LUMO bandgap, and electron density differences reveal that adjusting chain conformation appropriately could enhance polarity domain and electron polarization. The correlation between permittivity and segment dynamics of deformed molecules is explored, encompassing segment orientation, mean shift displacement, and diffusion coefficient. Following molecular chain orientation, the kinematic capability of the chain segment improves, which leads to an increase in the number and activity of effective dipoles and the enhancement of orientation polarization. Excessive stretching restricts the polymer molecular chain mechanically, reducing the number and activity of effective dipoles and negatively impacting electron polarization. The permittivity transitions from isotropic to anisotropic behavior when the system is subjected to strain. This study provides an interesting solution for research on multiscale responses and intrinsic mechanisms of pre-strain.
Deviations from ideality in solutions of dicarboxylic acid salts modeled within a BiMSA theory for flexible chains
Authors: Jaramillo-Gutiérrez Jaime , Bernard Olivier , Torres-Arenas José , Simonin Jean-Pierre
Published: December 2024

The binding mean spherical approximation theory is used to describe the thermodynamic properties of dicarboxylic acid salts by adding a chain term in the free energy. The dianions in these solutions are modeled as flexible charged chains composed of two, three, or four spheres. Five aqueous solutions of such salts are studied in different concentration ranges: dipotassium oxalate, disodium malonate, disodium succinate, potassium tartrate, and sodium tartrate. A description of the experimental deviations from ideality (osmotic and activity coefficients) for these salts is obtained. The model is compared with a previous one that does not include a chain contribution. It is found that the model with a chain contribution provides a more physically sound framework.
Time-resolved Coulomb explosion imaging of vibrational wave packets in alkali dimers on helium nanodroplets
Authors: Jyde Nicolaj K. , Kristensen Henrik H. , Kranabetter Lorenz , Christensen Jeppe K. , Hansen Emil , Carlsen Mads B. , Stapelfeldt Henrik
Published: December 2024

Vibrational wave packets are created in the lowest triplet state 13Σu+ of K2 and Rb2 residing on the surface of helium nanodroplets, through non-resonant stimulated impulsive Raman scattering induced by a moderately intense near-infrared laser pulse. A delayed, intense 50-fs laser pulse doubly ionizes the alkali dimers via multiphoton absorption and thereby causes them to Coulomb explode into a pair of alkali ions Ak+. From the kinetic energy distribution P(Ekin) of the Ak+ fragment ions, measured at a large number of delays, we determine the time-dependent internuclear distribution P(R, t), which represents the modulus square of the wave packet within the accuracy of the experiment. For both K2 and Rb2, P(R, t) exhibits a periodic oscillatory structure throughout the respective 300 and 100 ps observation times. The oscillatory structure is reflected in the time-dependent mean value of R, ⟨R⟩(t). The Fourier transformation of ⟨R⟩(t) shows that the wave packets are composed mainly of the vibrational ground state and the first excited vibrational state, in agreement with numerical simulations. In the case of K2, the oscillations are observed for 300 ps, corresponding to more than 180 vibrational periods with an amplitude that decreases gradually from 0.035 to 0.020 Å. Using time-resolved spectral analysis, we find that the decay time of the amplitude is ∼260 ps. The decrease is ascribed to the weak coupling between the vibrating dimers and the droplet.
Interfacial vs confinement effects in the anisotropic frequency-dependent dielectric, THz and IR response of nanoconfined water
Authors: Becker Maximilian R. , Netz Roland R.
Published: December 2024

We investigate the anisotropic frequency-dependent dielectric, THz and IR response of liquid water confined between two planar graphene sheets with force-field- and density-functional-theory-based molecular dynamics simulations. Using spatially resolved anisotropic spectra, we demonstrate the critical role of the volume over which the spectral response is integrated when reporting spatially averaged electric susceptibilities. To analyze the spectra, we introduce a unique decomposition into bulk, interfacial, and confinement contributions, which reveals that confinement effects on the spectra occur only for systems with graphene separation below 1.4 nm, for all frequencies. Based on this decomposition, we discuss the molecular origin of the main absorption features of nanoconfined water from the GHz to the IR regime. We show that, at low frequencies, the 15 GHz Debye peak of interfacial water is redshifted due to a slowdown of collective water reorientations. At high frequencies, the OH stretch at 100 THz blue shifts and a signature of free OH groups emerges, while the HOH bend mode at 50 THz is redshifted. Strikingly, in nanoconfinement, the 20 THz libration band shifts to below 15 THz and broadens drastically, spanning two orders of magnitude in frequency. These results are rationalized by the collective water motion and the structure of the hydrogen-bond network at the water–graphene interface and in two-dimensional water layers, which reveals the intricate behavior of nanoconfined water and its spectral properties.
Energy conversions at shock wave interaction with pulse discharge in profiled channel
Authors: Karnozova E. , Znamenskaya I. , Doroshchenko I. , Sysoev N. , Lutsky A.
Published: December 2024

The objective of this paper is to conduct a comprehensive investigation of the thermal and gas dynamic flow fields generated during the interaction of pulsed volume discharge plasma with high-speed channel flow. A comparative visualization was carried out using high-speed infrared thermography and shadowgraphy techniques. We examined phenomena related to both plasma and gas dynamic interactions within a special test section of the gas dynamic channel. The spatial–temporal characteristics of the thermal fields associated with these plasma and gas dynamic interactions were analyzed, together with infrared radiation intensity diagrams. The dynamics of discontinuities and inhomogeneities resulting from the interaction of shock waves with the pulsed volume discharge plasma—referred to as discontinuity breakdown—were also investigated. We compared two physical mechanisms of energy conversion into infrared radiation recorded by the thermal imager in the range of 1.5–5.1 μm. These mechanisms include low-temperature plasma emission from a sub-microsecond localized volume discharge and the sub-millisecond radiation from the inner surfaces of glass walls heated due to thermal conductivity at the interface with the gas flow boundary layer.
Interface Equilibrator: Numerical solutions to capillarity and wetting equilibrium and quasi-equilibrium problems
Authors: Soligno Giuseppe
Published: December 2024

This paper introduces Interface Equilibrator (IE), a new graphical-user-interface software for simulating the equilibrium shape of fluid–fluid interfaces in a wide range of wetting and capillarity problems. IE provides an easy-to-use three-dimensional computer-aided-design environment to define the problem's geometry (i.e., the solid surfaces and the fluids' volumes), by simply loading opportune triangular meshes, and chemistry, by selecting the value of the relevant experimental parameters (e.g., Young's contact angle). No other input is required. Then, IE calculates the fluid–fluid interface's equilibrium shape using a novel numerical methodology, presented in this paper, that consists in an energy-minimization Monte Carlo simulation alongside other built-in automated methods to, e.g., refine the fluid–fluid interface mesh according to its local curvature and polish it. The energy-minimization algorithm is based on a numerical approach introduced a few years ago [Soligno et al., “The equilibrium shape of fluid-fluid interfaces: Derivation and a new numerical method for Young's and Young–Laplace equations,” J. Chem. Phys. 141, 244702 (2014)] that is generalized here to handle unconstructed meshes with any topology and to include also new types of forces (e.g., due to a rotating system or to a line tension). In addition, several illustrative and scientifically interesting novel results are presented in this paper to demonstrate IE's versatility and capability of addressing a broad spectrum of research problems, relevant for many technological applications, such as microfluidics, fluid management at various length scales, printing, colloids, soldering for chip manufacture, etc. Finally, the paper reports numerous validation tests, where known analytic or numerical solutions are compared with IE's results to verify the correctness and accuracy of IE's calculations.
Steady motions of single spherical microswimmers in non-Newtonian fluids
Authors: Kobayashi Takuya , Yamamoto Ryoichi
Published: December 2024

In biological systems, microswimmers often propel themselves through complex media. However, many aspects of swimming mechanisms in non-Newtonian fluids remain unclear. This study considers the propulsion of two types of single spherical microswimmers (squirmers) in shear-thickening and shear-thinning fluids. The slip-driven squirmer propels faster/slower in shear-thickening/thinning fluids than in Newtonian fluids [C. Datt et al., J. Fluid Mech. 784, R1 (2015)]. In contrast, we discovered that a traction-driven squirmer exhibits the opposite trend, moving slower/faster in shear-thickening/thinning fluids than in Newtonian fluids. In addition, we have shown theoretically that Purcell's scallop theorem does not hold in non-Newtonian fluids when a squirmer with reciprocal surface motions is used. The present findings open up possibilities for the design of new types of microswimmers that can achieve translational motion from a single reciprocal motion in non-Newtonian fluids. Furthermore, we demonstrated that traction-driven squirmers swim faster and more efficiently in shear-thinning fluids than in Newtonian fluids. These findings highlight how the non-Newtonian rheology enhances both swimming speed and efficiency, suggesting further potential for optimizing locomotion performance otherwise impossible in Newtonian fluids.
A ferrofluid microrobot for manipulation in multiple workspaces
Authors: Zhang Chaonan , Zhao Yan , Wang Xiajing , Liang Shuzhang
Published: December 2024

Ferrofluid droplet has wide applications in bioanalysis manipulation. This study presents a ferrofluid microrobot for manipulation in different workspaces. Based on the deformation character of droplet, the ferrofluid microrobot has the capabilities of climbing the 3D (3-dimensional) surface, splitting in the channel, and transporting large particles. To manipulate in multiple workspaces with the capabilities, the size and magnetic force of ferrofluid are studied for suitable scenes. It shows that the diameter of 0.5 μl ferrofluid is around 980 μm. The manipulation force of different ferrofluid microrobots ranges from micronewton to millinewton. Subsequently, we have verified the manipulation of the ferrofluid microrobot on a 3D chip by permanent magnet. The ferrofluid microrobot can climb the stairs only when the height of the magnetic fluid is higher than twice the height of the stairs. Meanwhile, splitting of ferrofluid microrobot in the microfluidic chip has been successfully demonstrated. It indicates that the splitting influenced by the magnetic field and large magnetic force is easier to split the microrobot. Finally, the transportation of large polystyrene microparticles (150 μm) is confirmed by the ferrofluid microrobot. These capabilities show that the ferrofluid microrobot has the potential application advantage in biomedicine's micro-drug testing.
Ergodic relaxor state regulated energy storage properties in dielectrics
Authors: Lin Wei , Li Yang , Zhang Shumin , He Yunfei , Zhao Shifeng
Published: December 2024

Electrostatic energy storage based on dielectrics is fundamental for high-performance electrical systems. However, developing outstanding energy storage capabilities is challenging because the polarization, loss, and breakdown strength are firmly coupled and mutually restrictive. This work proposes a two-pronged strategy to break out the mutual clamp between these performance parameters by modulating the ergodicity and band structures in Aurivillius ferroelectric films. An inserting layer engineering is carried out using Bi4Ti3O12 as matrix and BiAlO3 as inserting layer. The intrinsic ergodic characteristics drive the realization in the arrangements of internal permanent dipoles through a macroscopically reversible interconversion between relaxor and ferroelectric phases, thereby modulating the pinched double hysteresis loops with both large polarization and low hysteresis. Moreover, the band structure associated with the breakdown strength is additionally regulated by orbital hybridization. Thus, ergodic relaxor ferroelectric film Bi5Ti3AlO15, exhibits an excellent energy storage performance with densities reaching as high as ∼131.8 J cm−3 and efficiencies exceeding 73%. This work overcomes the ubiquitous trade-off among polarization, hysteresis, and breakdown strength, offering extra insight into developing dielectric energy storage capacitors.
Inference of non-exponential kinetics through stochastic resetting
Authors: Blumer Ofir , Reuveni Shlomi , Hirshberg Barak
Published: December 2024

We present an inference scheme of long timescale, non-exponential kinetics from molecular dynamics simulations accelerated by stochastic resetting. Standard simulations provide valuable insight into chemical processes but are limited to timescales shorter than ∼1μs. Slower processes require the use of enhanced sampling methods to expedite them and inference schemes to obtain the unbiased kinetics. However, most kinetics inference schemes assume an underlying exponential first-passage time distribution and are inappropriate for other distributions, e.g., with a power-law decay. We propose an inference scheme that is designed for such cases, based on simulations enhanced by stochastic resetting. We show that resetting promotes enhanced sampling of the first-passage time distribution at short timescales but often also provides sufficient information to estimate the long-time asymptotics, which allows the kinetics inference. We apply our method to a model system and a peptide in an explicit solvent, successfully estimating the unbiased mean first-passage time while accelerating the sampling by more than an order of magnitude.