bluuebunny/crossref_metadata_2025 huggingface dataset:
Family of Gaussian wavepacket dynamics methods from the perspective of a nonlinear Schrödinger equation
Authors: J. L. Vaníček Jiří
Published: July 2023

Many approximate solutions of the time-dependent Schrödinger equation can be formulated as exact solutions of a nonlinear Schrödinger equation with an effective Hamiltonian operator depending on the state of the system. We show that Heller’s thawed Gaussian approximation, Coalson and Karplus’s variational Gaussian approximation, and other Gaussian wavepacket dynamics methods fit into this framework if the effective potential is a quadratic polynomial with state-dependent coefficients. We study such a nonlinear Schrödinger equation in full generality: we derive general equations of motion for the Gaussian’s parameters, demonstrate time reversibility and norm conservation, and analyze conservation of energy, effective energy, and symplectic structure. We also describe efficient, high-order geometric integrators for the numerical solution of this nonlinear Schrödinger equation. The general theory is illustrated by examples of this family of Gaussian wavepacket dynamics, including the variational and nonvariational thawed and frozen Gaussian approximations and their special limits based on the global harmonic, local harmonic, single-Hessian, local cubic, and local quartic approximations for the potential energy. We also propose a new method by augmenting the local cubic approximation with a single fourth derivative. Without substantially increasing the cost, the proposed “single-quartic” variational Gaussian approximation improves the accuracy over the local cubic approximation and, at the same time, conserves both the effective energy and symplectic structure, unlike the much more expensive local quartic approximation. Most results are presented in both Heller’s and Hagedorn’s parametrizations of the Gaussian wavepacket.
Experimental characterization of gaseous ion beams produced with the advanced ion source for hadrontherapy (AISHa) at 18 GHz
Authors: Castro G. , Leonardi O. , Chines F. , Costanzo G. , D’Agostino G. , Massara A. , Maugeri C. , Passarello S. , Russo F. , Siliato D. , Calabrese G. , Gammino S. , Celona L.
Published: July 2023

The Advanced Ion Source for Hadrontherapy (AISHa) is an electron cyclotron resonance ion source operating at 18 GHz, developed at the Istituto Nazionale di Fisica Nucleare-Laboratori Nazionali del Sud, with the aim of producing high intensity and low emittance highly charged ion beams for hadrontherapy purposes. Moreover, thanks to its unique peculiarities, AISHa is a suitable choice for industrial and scientific applications. In the framework of the INSpIRIT and IRPT projects, in collaboration with the Centro Nazionale di Adroterapia Oncologica, new candidates for cancer treatment are being developed. In particular, the paper presents the results of the commissioning of four ion beams of interest for hadrontherapy: H+, C4+, He2+, and O6+. Their charge state distribution in the best experimental conditions, their emittance, and brightness will be critically discussed, along with the role of ion source tuning and space charge effects in beam transport. Perspectives for further developments will also be presented.
Unveiling the energy transfer mechanism between aqueous colloidal NIR-II quantum dots and water
Authors: Yang Hongchao , Li Renfu , Sun Ziqiang , Zhang Yejun , Zhan Hongbing , Chen Xueyuan , Wang Qiangbin
Published: July 2023

Hydrophilic semiconductor quantum dots (QDs) with emission in the second near-infrared window (NIR-II) have been widely studied in bioimaging applications. In such cases, QDs are usually dispersed in water. As is known, water has strong absorbance in the NIR-II region. However, investigations on the interaction between NIR-II emitters and water molecules are ignored in previous studies. Herein, we synthesized a series of mercaptoundecanoic acid-coated silver sulfide (Ag2S/MUA) QDs with various emissions that partially or completely overlapped with the absorbance of water at 1200 nm. By constructing a hydrophobic interface of cetyltrimethylammonium bromide (CTAB) with MUA on the Ag2S QDs surface via forming an ionic bond, significant enhancement of Ag2S QDs photoluminescence (PL) intensity was observed, as well as a prolonged lifetime. These findings suggest that there is an energy transfer between Ag2S QDs and water in addition to the classical resonance absorption. Transient absorption and fluorescence spectra results revealed that the increased PL intensities and lifetime of Ag2S QDs originated from the suppressed energy transfer from Ag2S QDs to the water due to the CTAB bridged hydrophobic interfaces. This discovery is important for a deeper understanding of the photophysical mechanisms of QDs and their applications.
Enhanced energy transfer efficiency upon confining rhodamine B into zeolitic imidazolate frameworks
Authors: Hu Wenhui , Wang Denan , Chiromo Humphrey , Huang Jier
Published: July 2023

Enhancing the utilization of absorbed light is essential for enhancing the efficiency of solar energy conversion via artificial photosynthesis. In this work, we report the successful incorporation of Rhodamine B (RhB) into the pore of ZIF-8 (ZIF = zeolitic imidazolate framework) and the efficient energy transfer process from RhB to Co-doped ZIF-8. Using transient absorption spectroscopy, we show that energy transfer only occurs from RhB (donor) to Co center (acceptor) when RhB is confined into the ZIF-8 structure, which is in stark contrast to the system based on the physical mixture of RhB with Co-doped ZIF-8, where negligible energy transfer was observed. In addition, energy transfer efficiency increases with the concentration of Co and reaches a plateau when the molar ratio of Co to RhB reaches 32. These results suggest that RhB confined in the ZIF-8 structure is essential for energy transfer to occur, and energy transfer efficiency can be controlled by tuning the concentration of acceptors.
On the motion of hairpin filaments in the atmospheric boundary layer
Authors: Harikrishnan Abhishek , Rodal Marie , Klein Rupert , Margerit Daniel , Vercauteren Nikki
Published: July 2023

A recent work of Harikrishnan et al. [“Geometry and organization of coherent structures in stably stratified atmospheric boundary layers,” arXiv:2110.02253 (2021)] has revealed an abundance of hairpin-like vortex structures, oriented in a similar direction, in the turbulent patches of a stably stratified Ekman flow. In this study, hairpin-like structures are investigated by treating them as slender vortex filaments, i.e., a vortex filament whose diameter d is small when compared to its radius of curvature R. The corrected thin-tube model of Klein and Knio [“Asymptotic vorticity structure and numerical simulation of slender vortex filaments,” J. Fluid Mech. 284, 275 (1995)] is used to compute the motion of these filaments with the atmospheric boundary layer as a background flow. Our results suggest that the orientation of the hairpin filament in the spanwise direction is linked to its initial starting height under stable stratification, whereas no such dependency can be observed with the neutrally stratified background flow. An improved feature tracking scheme based on spatial overlap for tracking Q-criterion vortex structures on the direct numerical simulation data is also developed. It overcomes the limitation of using a constant threshold in time by dynamically adjusting the thresholds to accommodate the growth or deterioration of a feature. A comparison between the feature tracking and the filament simulation reveals qualitatively similar temporal developments. Finally, an extension of the asymptotic analysis of Callegari and Ting [“Motion of a curved vortex filament with decaying vortical core and axial velocity,” J. Appl. Math. 35, 148–175 (1978)] is carried out to include the effect of gravity. The results show that, in the regime considered here, a contribution from the gravity term occurs only when the tail of an infinitely long filament is tilted at an angle relative to the wall.
Implementation of the Toffoli and Peres reversible logic gates using magnetic skyrmions in operational gates
Authors: Costilla J. I. , Alegre J. W. , Talledo A. , Pujada B. R.
Published: July 2023

Micromagnetic simulations have been used to create reversible logic gates that utilize magnetic skyrmions as input and output signals. The geometrical design of the logic devices consists of a two-dimensional assembly of ferromagnetic nanotracks, resembling rectangular grooves. Drawing an analogy to the billiard-ball model, this study takes into account elastic collisions between magnetic skyrmions and introduces the concept of control skyrmion. The application of spin-polarized currents to the system induces the motion of magnetic skyrmions along the nanotracks. The synchronized movement of magnetic skyrmions across the operational logic gates, required for their interaction, is achieved by incorporating multiple triangular magnetic notches along the nanotracks. Short polarized current pulses are then applied through the logic gates to facilitate this process. We have successfully implemented the XOR/AND and Full Adder logic gates as well as the reversible Toffoli and Peres logic gates using skyrmion-based architectures for computing. Our results offer valuable guidelines for leveraging magnetic skyrmions as digital signals in skyrmion-based computing systems.
On the bandgap underestimation of delafossite transparent conductive oxides CuMO2 (M = Al, Ga and In): Role of pseudopotentials
Authors: Shen Jiale , Liu Haitao , Li Yuanchang
Published: July 2023

We report a first-principles study on the electronic and optical properties of delafossite CuMO2 (M = Al, Ga and In) using the recently developed hybrid functional pseudopotentials. We obtain trends of the fundamental and optical gaps with increasing M-atomic number, in agreement with experiment. In particular, we reproduce the experimental fundamental gap, optical gap, and Cu 3d energy of CuAlO2 almost perfectly, in contrast to the various calculations that have traditionally focused on valence electrons, which are unable to reproduce these key properties simultaneously. Since all that distinguishes our calculations is simply the use of a different Cu pseudopotential with a partially exact exchange interaction, this suggests that an inappropriate description of the electron–ion interaction may play a role in the density functional theory bandgap problem for CuAlO2. Applying Cu hybrid pseudopotentials to CuGaO2 and CuInO2 is also effective, yielding optical gaps that are very close to experiment. However, due to the limited experimental data for these two oxides, a comprehensive comparison as that for CuAlO2 is not possible. Furthermore, our calculations yield large exciton binding energies for delafossite CuMO2, all around 1 eV.
Strain effects on magnetic compensation and spin reorientation transition of Co/Gd synthetic ferrimagnets
Authors: Masciocchi Giovanni , Kools Thomas J. , Li Pingzhi , Petrillo Adrien A. D. , Koopmans Bert , Lavrijsen Reinoud , Kehlberger Andreas , Kläui Mathias
Published: July 2023

Synthetic ferrimagnets are an attractive material class for spintronics as they provide access to all-optical switching of magnetization and, at the same time, allow for ultrafast domain wall motion at angular momentum compensation. In this work, we systematically study the effects of strain on the perpendicular magnetic anisotropy and magnetization compensation of Co/Gd and Co/Gd/Co/Gd synthetic ferrimagnets. First, the spin reorientation transition of a bilayer system is investigated in wedge type samples, where we report an increase in the perpendicular magnetic anisotropy in the presence of in-plane strain. Using a model for magnetostatics and spin reorientation transition in this type of system, we confirm that the observed changes in anisotropy field are mainly due to the Co magnetoelastic anisotropy. Second, the magnetization compensation of a quadlayer is studied. We find that magnetization compensation of this synthetic ferrimagnetic system is not altered by external strain. This confirms the resilience of this material system against strain that may be induced during the integration process, making Co/Gd ferrimagnets suitable candidates for spintronics applications.
Electrolubrication in flowing liquid mixtures
Authors: Tsori Yoav
Published: July 2023

We describe the “electrolubrication” occurring in liquid mixtures confined between two charged surfaces. For a mixture of two liquids, the effective viscosity decreases markedly in the presence of a field. The origin of this reduction is field-induced phase separation, leading to the formation of two low-viscosity lubrication layers at the surfaces. These layers facilitate larger strain at a given stress. The effect is strong if viscosities of the two liquids are sufficiently different, the volume fraction of the less viscous liquid is small, the gap between the surfaces is small, and the applied potential is large. The phase separation relies on the existence of dissociated ions in the solution. The effective viscosity is reduced by a factor α; its maximum value is the ratio between the viscosities of the two liquids. In most liquids, α∼1–10, and in mixtures of water and glycerol, α∼80–100 under relatively small potentials.
Microstructure and rheology of shear thickening colloidal suspensions under transient flows
Authors: Lee Yu-Fan , Whitcomb Kevin , Wagner Norman J.
Published: July 2023

Novel measurements of the spatiotemporal microstructure of a continuous shear thickening colloidal suspension under shear cessation and reversal using small angle neutron scattering in a 1–2 shear cell are presented for moderate to high Péclet numbers. In the shear cessation experiments from high Péclet shear flow, two-step relaxation mechanism is found. Particles first readily diffuse on a characteristic timescale of single particle Brownian motion, followed by slower relaxation dynamics on a timescale of short-time self-diffusion when caging effects start dominating. In the shear reversal experiment, the unchanged scattering intensity and the quick flip in anisotropic structure around the shear thickened state suggest the persistence of hydroclusters without transitioning through the equilibrium structure, at least in a time resolution of 0.01 s. Access to the time evolution of microstructure provides valuable insights into the spatiotemporal details of interparticle interactions governing colloidal suspension rheology, such as Brownian, hydrodynamic, and nanotribological forces.
Vacancy-induced magnetic states in TiO2 surfaces
Authors: Friák Martin , Quynh Nhu Tran , Meduňa Mojmír , Gazdová Kristýna , Pavlů Jana , Munzar Dominik , Hoa Hong Nguyen
Published: July 2023

We present a combined experimental and theoretical study of surface-related magnetic states in TiO2. Our experiments on nano-sized thin films of pure TiO2 have suggested that the observed room-temperature magnetism originates from defects, in particular, from the surface of thin films as well as from point defects, such as oxygen vacancies located mainly at the surface. Clarifying this phenomenon is very important for harnessing magnetic properties of pristine TiO2 films in future spintronic applications but a detailed experimental investigation is very demanding. Therefore, quantum-mechanical density functional theory calculations were performed for (i) bulk anatase TiO2, (ii) bulk-like TiO2-terminated vacancy-free (001) surfaces, (iii) vacancy-containing TiO-terminated (001) surfaces, (iv) TiO0.75-terminated (001) surfaces with additional 25% surface oxygen vacancies, as well as (v) oxygen-terminated (001)-surfaces. Our fixed-spin-moment calculations identified both the bulk and the bulk-like terminated vacancy-free TiO2-terminated (001) surfaces as non-magnetic. In contrast, oxygen vacancies in the case of TiO-terminated and TiO0.75-terminated (001) surfaces lead to ferromagnetic and rather complex ferrimagnetic states, respectively. The spin-polarized atoms are the Ti atoms (due to the d-states) located in the surface and sub-surface atomic planes. Last, the O-terminated surfaces are also magnetic due to the surface and sub-surface oxygen atoms and sub-surface Ti atoms (but their surface energy is high).
Universal rule of revealing energy-band diagrams at various semiconductor interfaces: The influence of film thickness and dielectric constants
Authors: Yang Jin-Peng , Tang Qing-Su
Published: July 2023

Obtaining detailed energy-band diagram is always critically important at various semiconductor interfaces due to its direct instruction for optimizing and improving the performance of (opto-)electronic devices, which, therefore, always has been paid attention to by scientists. Despite the technological relevance of depicting energy-band diagrams at different types of semiconductors (inorganic, organic, and hybridized scenarios), the discrepancy at these interfaces still exists, and a reliable model that could potentially unify the full range of phenomena observed from these interfaces is still lacking. Here, we develop a theoretical framework to fill in this gap so that it could be capable of reproducing various band alignments at different semiconductor interfaces both qualitatively and quantitatively. Our model could further allow us to resolve some conflicting views in the literature related to the influence of substrate work functions, which should be considered differently between inorganic and organic semiconductor interfaces. Our results also highlight the importance of dielectric constant differences and the film thickness as critical factors in driving charge transfer at semiconductor interfaces through integrating different density of states with Fermi–Dirac distribution functions in various semiconductors, which hopefully could promote the numerical study on developing functional semiconductor devices.
Couple stress fluid flow enclosing a solid sphere in a porous medium: Effect of magnetic field
Authors: Maurya Pankaj Kumar , Deo Satya , Maurya Deepak Kumar
Published: July 2023

The present research explores the Stokesian flow of an axisymmetric, incompressible couple stress fluid through a porous material enclosing a solid sphere in the presence of a uniform magnetic field. Utilizing the separation of variables technique, the problem is solved analytically. Expressions for the stream function, velocity components, vorticity component, fluid pressure, stress tensors, and couple stresses are obtained, which involved modified Bessel functions, trigonometric functions, and algebraic functions. Impenetrability, no-slip, and nil-vorticity conditions have been applied at the interface. A novel result for the drag force experienced by a solid sphere enclosed in porous material under the applied uniform magnetic field is reported. The evidence already in place leads to the identification and validation of our results for flow past the impermeable sphere. Tangential velocity and normal velocity, drag force, and streamline patterns are displayed for different values of flow parameters, which incorporate the Hartmann number, permeability parameter, and couple stress parameter.
Experimental demonstration of superdirective spherical dielectric antenna
Authors: Gaponenko Roman , Sidorenko Mikhail S. , Zhirihin Dmitry , Rasskazov Ilia L. , Moroz Alexander , Ladutenko Konstantin , Belov Pavel , Shcherbakov Alexey
Published: July 2023

An experimental demonstration of directivities exceeding the fundamental Kildal limit, a phenomenon called superdirectivity, is provided for spherical high-index dielectric antennas with an electric dipole excitation. A directivity factor of about 10 with a total efficiency of more than 80% for an antenna having a size of a third of the wavelength was measured. High directivities are shown to be associated with constructive interference of particular electric and magnetic modes of an open spherical resonator. Both analytic solutions for a point dipole and a full-wave rigorous simulation for a realistic dipole antenna were employed for optimization and analysis, yielding an excellent agreement between experimentally measured and numerically predicted directivities. The use of high-index low-loss ceramics can significantly reduce the physical size of such antennas while maintaining their overall high radiation efficiency. Such antennas can be attractive for various high-frequency applications, such as antennas for the Internet of Things, smart city systems, 5G network systems, and others. The demonstrated concept can be scaled in frequency.
Low-energy argon ion bombardment-induced decomposition of physisorbed hydrofluorocarbons on silicon nitride surfaces: A computational mechanistic study
Authors: Cheng Erik S. , Hwang Gyeong S.
Published: July 2023

Using a combination of tight binding molecular dynamics and ab initio molecular dynamics simulations, we study the mechanisms of bombardment-induced decomposition of hydrofluorocarbons (HFCs) physisorbed on silicon nitride for ion energies of ≤35 eV. We propose three key mechanisms by which bombardment-driven HFC decomposition can occur, focusing on the two pathways observed at these low ion energies: “direct decomposition” and “collision assisted surface reactions (CASRs).” Our simulation results clearly demonstrate the importance of the presence of favorable reaction coordinates for enabling CASR, which dominates at lower energies (≈11 eV). At higher energies, direct decomposition becomes more favored. Our work also predicts that the primary decomposition pathways for CH3F and CF4 are CH3F → CH3 + F and CF4 → CF2 + 2F, respectively. The fundamental details of these decomposition pathways and the decomposition products formed under ion bombardment have implications for plasma-enhanced atomic layer etching process design that will be discussed.
Nine new species of Australian Nicotiana (Solanaceae)
Authors: Chase Mark W. , Christenhusz Maarten J. M. , Cauz-Santos Luiz A. , Nollet Felipe , Bruhl Jeremy J. , Andrew Damien D. , Palsson Ruth , Jobson Richard W. , Taseski Guy M. , Samuel Rosabelle
Published: July 2023

Nine new species in Australian Nicotiana section Suaveolentes are described, including N. clarksonii M.W.Chase & Christenh., N. erytheia M.W.Chase & Christenh., N. latifolia M.W.Chase & Christenh., N. latzii M.W.Chase, R.W.Jobson & Christenh., N. gibbosa M.W.Chase, D.D.Andrew & J.J.Bruhl, N. olens M.W.Chase & Christenh., N. praecipitis M.W.Chase & K.Durham, N. karara M.W.Chase & Christenh. and N. bungonia M.W.Chase & Taseski. Some have been known from herbarium specimens for a long time, but their distinction from other species concepts was unsuspected until DNA studies showed their divergent nature. Others are known from one or only a few new localities. All are morphologically and genetically distinct from their close relatives. Increased sampling of populations in our molecular studies has led us to the conclusion that the widespread, recently described species N. insecticida is a species complex, comprising as many as six genetically distinct taxa, one of which includes material from the type locality of N. hesperis. Here, we describe a new name, N. erytheia, for all material we previously assigned to N. hesperis that is phylogenetically distinct from that of the type locality. To make the relationships of the new species clearer, we provide a tree produced by analysis of nuclear (RADseq) DNA data.
Millikan’s consistency testers and the cultural evolution of concepts
Authors: Shea Nicholas
Published: July 2023

Ruth Millikan has hypothesised that human cognition contains ‘consistency testers’. Consistency testers check
whether different judgements a thinker makes about the same subject matter agree or conflict. Millikan’s suggestion is that, where
the same concept has been applied to the world via two routes, and the two judgements that result are found to be inconsistent,
that makes the thinker less inclined to apply those concepts in those ways in the future.

If human cognition does indeed include such a capacity, its operation will be an important determinant of how
people use concepts. It will have a major impact on which concepts they deploy and which means of application (conceptions) they
rely on. Since consistency testers are a selection mechanism at the heart of conceptual thinking, they would be crucial to
understanding how concepts are selected  – why some are retained and proliferate and others die out. Hence, whether consistency
testers for concepts exist, and how they operate, is an important question for those seeking to understand the cultural evolution
of concepts, and of the words we use to express them.
Zooming in on the notion of metaphoricity
Authors: Julich-Warpakowski Nina , Jensen Thomas Wiben
Published: July 2023

The present contribution addresses the notion of metaphoricity and discusses different positions in relation to this complex and multi-dimensional phenomenon. Generally, the notion of metaphoricity is used when metaphor is not considered a binary category anymore, or when the status of an expression as metaphorical is at stake (e.g. in discussions of metaphor identification). We will focus on the first understanding of metaphoricity as a scalar phenomenon. Despite the fact that the term is used more and more in the metaphor literature, it is often unclear what it actually entails, e.g. how metaphor is gradable. To shed light on this theoretical and methodological problem, in this paper we will discuss different notions of the term metaphoricity by illustrating how metaphoricity is understood and how it can be operationalized and studied.
Semantic distance predicts metaphoricity and creativity judgments in synesthetic metaphors
Authors: Winter Bodo , Strik-Lievers Francesca
Published: July 2023

This paper discusses a way of operationalizing metaphoricity quantitatively using a numerical measure of the semantic distance between two domains. We demonstrate the construct validity of this measure with respect to metaphoricity and creativity judgments in the domain of English synesthetic metaphors – expressions such as sweet melody and loud color that involve combinations of terms from conceptually distinct sensory modalities. In a pre-registered study, we find that a continuous measure of sensory modality difference predicts metaphoricity and creativity judgments. While our results use synesthetic metaphors as a test case, it is possible to extend the application of our measure of semantic distance to other metaphorical expressions. In addition to demonstrating the utility of this measure, this work also demonstrates the utility of rating data in the domain of metaphor research.
The semantics of a parallel reality
Authors: Di Biase-Dyson Camilla
Published: July 2023

This paper considers the use of figurative language when intangible or supernatural phenomena are described in language. The case studies are derived from texts written in Ancient Egyptian, an extinct Afroasiatic language (ca. 3200 bce–1300 ce). It is argued that a MIPVU-based analysis, otherwise very useful for interrogating all kinds of texts, even those from the ancient world, needs to be modified to account for the layers of meaning encountered in texts in which a deity is being described. A more nuanced approach, which considers the scalarity of metaphor and reconsiders the conceptual modelling of metaphorical language in a culturally sensitive way, is proposed. As such, the methods proposed here may be useful for scholars working on metaphor in texts with religious content.
Acquisition of estar + adjective in L2 Spanish by L1 French and Portuguese speakers
Authors: Guijarro-Fuentes Pedro , Amenós-Pons José , Ahern Aoife
Published: July 2023

This paper reports the developmental stages of the acquisition of estar in stage-level predicate
constructions in the L2 Spanish grammar of native speakers of French and Portuguese. Copular verbs exist in the L1s of both
learner groups; however, only in Portuguese is there an aspectual contrast, with copula selection conditions that partially differ
from those of ser and estar in Spanish. The study used data extracted from the Corpus de
Aprendices de Español (CAES), made up of written texts produced by L2 Spanish learners from CEFR A1 to C1 levels. We attempt to
analyse whether, and to what degree, these L2 learners are sensitive to estar copula restrictions in adjective
constructions. Our analysis of the written production of 143 L1 French speakers and 361 L1 Portuguese speakers showed differing
acquisitional patterns depending on the L1. We consider that the estar overextension, found in the learners’
productions, is related to the process of developing the ability to identify the specific features that distinguish the use of
copular verbs in the interlanguage of our learners. Our findings, thus, provide a more fine-grained description of the semantic
representation and access of interpretable features in L2 Spanish with special relevance to current hypotheses on Second Language
Acquisition such as the Feature Reassembly Hypothesis (Lardiere
2009).
Phonic mitigation markers for disagreement in interviews of university learners of Spanish as foreign language
Authors: Medina Soler María Isabel , Ainciburu María Cecilia
Published: July 2023

In previous studies of the mitigators that occur when a speaker wants to show disagreement with his or her interlocutor, morphosyntactic markers occupy the most relevant part. In oral communication, however, phonic markers play a central role. This research presents the analysis of these markers in a corpus of interviews with B1 level university exchange students (CEFR). The aim is to check for the presence of phonic attenuation markers when foreign students express a divergent opinion in Spanish from that expressed by the native speaker. The analysis leads to a categorization of these markers and attempts to provide empirical basis for a better understanding of the phonic markers in the academic interlanguage.
An overview on the microstructure and properties of Fe/Ti based dissimilar joints
Authors: Prasanthi T. N. , Sudha C. , Saroja S.
Published: July 2023

Joining of Ti and Fe-based alloys is challenging due to the formation of deleterious phases at the interface. Since fusion welding is unsuitable for the purpose, over the years, many solid-state welding techniques have been tried. This review provides a comparison of different solid-state joining methods used for Fe/Ti alloys with focus on the structural transformations in base materials, effect of process parameters on interface microstructure, its evolution and kinetics with thermal aging and structure–property correlation. Structural transformations in diffusion couples (near-equilibrium condition) are compared with those in weldments and a perspective is provided on the role of defects and alloying additions in enhancing/retarding reaction zone formation under both equilibrium and non-equilibrium conditions.
Corrosion, fatigue and wear of additively manufactured Ti alloys for orthopaedic implants
Authors: Tjandra J. , Alabort E. , Barba D. , Pedrazzini S.
Published: July 2023

Additive manufacturing (AM) allows for the fabrication of custom orthopaedic implant devices which have complex geometries and similar mechanical properties to bone. This paper reviews the corrosion, fatigue and wear properties of AM Ti alloys to confirm their safety for use in orthopaedic implants. Specifically, AM Ti lattice geometries are highlighted due to their improved osseointegration and better modulus matching with that of bone, making them an attractive option for more durable implant devices. Finally, the properties of current implants made via AM are compared with that made via conventional manufacturing methods to confirm their overall safety.
Effects of Ga and in on the properties of Zn-Al sacrificial anodes
Authors: Shao Junqi , Yang Fei , Wang Jian , Deng Shenghua , Liang Yong , Zhao Hongjin , Deng Tongsheng , Xu Liang
Published: July 2023

The influence of Ga and In on the microstructure and electrochemical performance of a Zn-Al alloy was investigated. It was found that the microstructure of the Zn-Al sacrificial anode can be significantly refined by Ga and In, but excess Ga or In leads to segregation. Electrochemical tests show that Zn-0.5Al-0.07 Ga and Zn-0.5Al-0.1In have the most negative OCPs, the corrosion products of which can easily flake off from the corroded surface, showing the good performance of cathodic protection. A small amount of Ga and In contribute to the corrosion of the Zn-Al alloy; however, excess Ga or In can improve the corrosion resistance of the alloy by refining the grains and making the surface of the oxide film form quickly.
On the flow of perfect energy tensors
Authors: Sáez Juan Antonio , Mengual Salvador , Ferrando Joan Josep
Published: July 2023

The necessary and sufficient conditions are obtained for a unit time-like vector field u to be the unit velocity of a divergence-free perfect fluid energy tensor. This plainly kinematic description of a conservative perfect fluid requires considering eighteen classes defined by differential concomitants of u. For each of these classes, we get the additional constraints that label the flow of a conservative energy tensor, and we obtain the pairs of functions

{
ρ
,
p
}

, energy density and pressure, which complete a solution to the conservation equations.
A minimized electron cyclotron resonance ion thruster for China’s space-borne gravitational wave detection missions
Authors: Meng Sheng-Feng , Zhu Xi-Ming , Yu Da-Ren
Published: July 2023

Space-borne gravitational wave (GW) detection spacecraft works in the state of drag free for which a disturbance reduction system is utilized to offset the non-conservative force. The key actuator of drag-free control loop is a micro-thruster with the performance of a high precision thrust and wide-range operations. Ion thruster, such as electron cyclotron resonance ion thruster (ECRIT), is one of the options because its thrust can be controlled precisely by the method of beam current feedback. However, there is still a barrier for the conventional ECRIT to achieve the low thrust of 1 μN as required in space-borne GWs detection missions due to its radial structure. In this work, a minimized ECR ion thruster (mini-ECRIT) is designed by a new idea that it employs an axial ring-cusped field to exploit the low-pressure adaptability of resonance heating. The mini-ECRIT is tested and results in a dynamic thrust range of 1–100 μN, a resolution of 0.1 μN, a thrust noise of 0.1 μN/Hz1/2, and a response time of about 10 ms. In addition, the specific impulse of this thruster can reach as high as 510 s at low thrust 5 μN, being higher than that of previous ion thrusters by a factor of about 5, which may significantly reduce the propellant consumption. This minimized ECR ion thruster may support China’s space-borne GW detection missions such as TianQin.
Relativistic bulk viscous fluids of Burgers type and their presence in neutron stars
Authors: Gavassino L
Published: July 2023

It is well known that a mixture of two chemical components undergoing one chemical reaction is a bulk viscous fluid, where the bulk stress evolves according to the Israel-Stewart theory. Here, we show that a mixture of three independent chemical components undergoing two distinct chemical reactions can also be viewed as a bulk viscous fluid, whose bulk stress now is governed by a second-order differential equation which reproduces the Burgers model for viscoelasticity. This is a rigorous and physically motivated example of a fluid model where the viscous stress does not undergo simple Maxwell-Cattaneo relaxation, and can actually overshoot the Navier–Stokes stress. We show that, if one accounts for muons, neutron star matter is indeed a bulk viscous fluid of Burgers type.
Quantum causality in κ-Minkowski and related constraints
Authors: Franco Nicolas , Hersent Kilian , Maris Valentine , Wallet Jean-Christophe
Published: July 2023

We study quantum causal structures in

1
+
1

κ-Minkowski space-time described by a Lorentzian Spectral Triple whose Dirac operator is built from a natural set of twisted derivations of the κ-Poincaré algebra. We show that the Lorentzian Spectral Triple must be twisted to accommodate the twisted nature of the derivations. We exhibit various interesting classes of causal functions, including an analog of the light-cone coordinates. We show in particular that the existence of a causal propagation between two pure states, the quantum analogs of points, can exist provided quantum constraints, linking the momentum and the space coordinates, are satisfied. One of these constraints is a quantum analog of the speed of light limit.
Gravity theories with local energy-momentum exchange: a closer look at Rastall-like gravity
Authors: Vanzella Daniel A Turolla
Published: July 2023

Einstein’s famous equivalence principle is certainly one of the most striking features of the gravitational interaction. In a strict reading, it states that the effects of gravity can be made to disappear locally by a convenient choice of reference frame. As a consequence, no covariantly-defined net gravitational (point-wise) force should exist and energy-momentum of all matter and interaction fields combined, with gravity excluded, should be locally conserved. Although elegant, this represents a strong constraint on the dynamics of a gravitating system and it is only logical to question its naturality and observational basis. This is the purpose of the present work. For concreteness sake, we analyze, in the context of metric (torsion-free) theories of gravity, the simplest phenomenological model which allows for local energy-momentum exchange between the spacetime and matter/interaction fields while preserving the seemingly more natural principle of general covariance. This concrete model turns out to be a generalization of the socalled Rastall’s theory, with one important advantage: criticisms made to the latter, which are often used to dismiss it as a viable or interesting model, do not apply to the former in a Universe containing ‘dark’ ingredients, such as ours—a connection which seems to have been overlooked thus far. We conclude by exploring the consequences of our Rastall-like model to standard (astrophysical and cosmological) gravitational scenarios.
Polarization control of RABBITT in noble gas atoms
Authors: Kheifets Anatoli S , Xu Zhongtao
Published: July 2023

The mutual angle formed by the non-collinear polarization axes of two laser pulses is used to control two-photon extreme ultraviolet and infrared ionization of noble gas atoms in the process of reconstruction of attosecond bursts by beating of two-photon transitions (RABBITT). The magnitude and the phase of this beating can be controlled very efficiently by the mutual polarization angle. The mechanism of this control can be understood within the lowest order perturbation theory and the soft photon approximation. We offer a very sensitive test on the polarization control of the angular dependent RABBITT process which validates our numerical simulations. We apply this test to the recent theoretical and experimental results of polarization controlled RABBITT on hydrogen and helium by Boll et al (2023 Phys. Rev. A 107 043113) and heavier noble gases by Jiang et al (2022 Nat. Commun.
13 5072).
Two-dimensional Dirac phonons without/with inversion symmetry
Authors: Wang Chenyang , Yu Wei-Wang , Liu Ying , Zhang Xiaoming , Jin Lei , Liu Cong , Liu Guodong
Published: July 2023

In a recent study, two-dimensional Dirac phonons that are protected by nonsymmorphic symmetries in spinless systems were systematically investigated. However, the focus of this study was on the classification of Dirac phonons. To address the gap in the research on the topological features of 2D Dirac phonons based on their effective models, we classified the 2D Dirac phonons into two classes: without or with inversion symmetry, thereby clarifying the minimal symmetry requirements for enforcing 2D Dirac points. Based on symmetry analysis, we discovered that screw symmetries, together with time-reversal symmetry, play an essential role in the existence of Dirac points. To validate this result, we constructed the k·p model to describe the Dirac phonons and discussed their topological features accordingly. We found that a 2D Dirac point could be considered as a composition of two 2D Weyl points with opposite chirality. Furthermore, we provided two concrete materials to demonstrate our findings. Overall, our work provides a more detailed study of 2D Dirac points in spinless systems and clarifies their topological features.
Metamagnetic transition in the two f orbitals Kondo lattice model
Authors: Thomas Christopher , Burdin Sébastien , Lacroix Claudine
Published: July 2023

In this work, we study the effects of a transverse magnetic field in a Kondo lattice model with two f orbitals interacting with the conduction electrons. The f electrons that are present on the same site interact through Hund’s coupling, while on neighboring sites they interact through intersite exchange. We consider here that part of f electrons are localized (orbital 1) while another part (orbital 2) are delocalized, as it is frequent in uranium systems. Then, only electrons in the localized orbital 1 interact through exchange interaction with the neighboring ones, while electrons in orbital 2 are coupled with conduction electrons through a Kondo interaction. We obtain a solution where ferromagnetism and Kondo effect coexist for small values of an applied transverse magnetic field for

T
→
0

. Increasing the transverse field, two situations can be obtained when Kondo coupling vanishes: first, a metamagnetic transition occurs just before or at the same time of the fully polarized state, and second, a metamagnetic transition occurs when the spins are already pointing out along the magnetic field.
An optical non-contact flow-meter of conveyor belt based on FPGA
Authors: Du Hao , Wang Huifeng , Zhang Xiaowei , Guan Yueyuan , Shi Haonan , Song Shangzhen , Huang He
Published: July 2023

Aiming at the disadvantages of the existing conveyor belt flow monitoring, this research builds a conveyor belt optical dynamic flow-meter based on field programmable gate array (FPGA) by using FPGA image processing technology and the method of measuring material volume to measure the volume of conveyor belt material, which uses the principle of laser triangulation. The flow-meter takes FPGA as the core and drives two complementary metal oxide semiconductor (CMOS) cameras to collect light strips on material surface at the same time. Then, filter, binarization, center extraction and image stitching are performed on the collected light strips. Finally, the material volume is calculated by linear interpolation and Riemann sum. The image acquisition and processing of the flow-meter and the final volume calculation are implemented in the form of hardware in FPGA, the calibration and result display of system parameters is realized in the form of software in advanced RISC machine (ARM). It can be shown that the relative error of the volume measured by the flow-meter is less than 0.05 through experiment, and the material volume flow rate of the conveyor belt can be measured and displayed accurately in real-time, which makes up for the deficiency of the existing flowmeter. This system is of great significance for the informatization transformation of the conveyor belt and the realization of digital production and intelligent manufacturing.
Rolling bearing incipient fault feature extraction using impulse-enhanced sparse time-frequency representation
Authors: Zhu Hongxuan , Jiang Hongkai , Yao Renhe , Yang Qiao
Published: July 2023

Incipient faults features are often extremely weak and susceptible to heavy noise, making it challenging to obtain the concentrated faulty energy ridges in the time-frequency domain. Thus, a novel impulse-enhanced sparse time-frequency representation (IESTFR) method is proposed in this paper. First, the time-rearranged multisynchrosqueezing transform is utilized to produce a time-frequency representation (TFR) with a high energy concentration for faulty impulses. Next, a new non-convex penalty function is constructed by the hyperbolic tangent function, which can enhance the periodic impulsivity of sparse TFR for more obvious fault characteristic frequency. Moreover, the time-frequency transform is evaluated and compared by simulated signals and a selection strategy for the regularization parameter is designed. Simulated signals and two experimental signals are applied to verify the effectiveness of IESTFR, and the results show that IESTFR is effective and superior in bearing incipient fault feature extraction.
Numerical simulation of mechanical behaviors and intergranular fracture of polycrystalline Nb3Sn and superconducting filaments
Authors: Ding He , De Marzi Gianluca , Gao Yuanwen
Published: July 2023

Given the importance of large-scale engineering applications of the superconducting compound Nb3Sn, both its use and performance under certain operating conditions have attracted the interest of applied superconductivity researchers and material scientists for several years now. Huge efforts are directed toward understanding the response to applied loads and predicting fracture damage within their internal microstructure; this is fundamental in the design of superconducting coils and magnets which must meet stringent requirements in terms of maximum thermal and electromagnetic loads. In this paper, the fracture behaviors in polycrystalline Nb3Sn and Nb3Sn filaments with composite structures are investigated using the micromechanical finite element (FE) models with Voronoi tessellation. First, the 2D and 3D Voronoi FE models of the polycrystalline Nb3Sn tensile tests are developed and validated to provide insight into the cracking behavior in the intergranular brittle fracture of polycrystalline Nb3Sn. A cohesive zone model is used to simulate crack propagation at the grain level model including grain boundary zones. It is found that the pre-existing cracks of polycrystals and martensitic phase transformation of grains significantly impact the fracture properties in polycrystalline Nb3Sn. Second, detailed FE models of powder-in-tube (PIT) and bronze route filaments with Voronoi structures for fracture analysis are then developed on the basis of experimental observations of sectional morphologies. The mechanism of crack initiation and propagation under tensile load have been investigated by analyzing the mechanical properties of each component and the characteristics of multi-scale composite structures of filaments. Furthermore, the damage situation is investigated in PIT filaments undergoing transverse compressive load. The proposed simulation method in this paper can be extended to the fracture and damage analysis of Nb3Sn superconducting wires with different layouts and fabrication processes.