bluuebunny/crossref_metadata_2025 huggingface dataset:
Evaluation protocol for revealing magnonic contrast in TR-STXM measurements
Authors: Zingsem Benjamin , Feggeler Thomas , Meckenstock Ralf , Spoddig Detlef , Schaffers Taddäus , Pile Santa , Ohldag Hendrik , Farle Michael , Wende Heiko , Ney Andreas , Ollefs Katharina
Published: April 2023

We present a statistically motivated method to extract magnonic contrast from time-resolved scanning transmission x-ray microscopy (TR-STXM) measurements. TR-STXM is an element-specific method for resolving spin-dynamics in space and time. It offers nanometer spatial resolution and picosecond temporal resolution. The presented method makes it possible to obtain phase and amplitude profiles of spin-waves from STXM measurements. Furthermore, it allows for a rigorous transformation to reciprocal magnon k⃗-space, revealing k⃗-dependent magnon properties such as the magnon dispersion in three dimensions and for all directions of the magnetic anisotropy. We demonstrate our method using X-band ferromagnetic resonance on a micrometer-sized permalloy assembly.
Effect of electronic transitions on near edge optical properties of off-stoichiometric boron carbide thin films
Authors: Modi Mohammed H. , Gupta Rajkumar , Yadav Praveen K. , Gupta Shruti , Mukherjee C. , Idir Mourad
Published: April 2023

In the present study, soft x-ray optical properties of off-stoichiometric boron carbide thin films are investigated, and the structure and chemical composition of the film is analyzed using angle dependent x-ray reflectivity and x-ray photoelectron spectroscopy techniques. Energy dependent soft x-ray reflectivity measured at a fixed grazing angle of 1.5° is used to determine the optical constants in the boron K edge region by applying the Kramers–Kronig technique. The measured optical constants show near edge fine features corresponding to σ* and π* resonances. The electronic transitions corresponding to σ* resonance cause a 40%–75% increase in the delta value in the above boron K edge region. The π* transitions corresponding to off-stoichiometric nature of the boron carbide are observed in the absorption spectra near ∼192.7 eV. Details of the measured soft x-ray optical properties of the off-stoichiometric boron carbide thin film are discussed.
Enhancing stiffness-based cell sorting using power-law fluids in ridged microchannels
Authors: Chrit Fatima Ezahra , Barton Joshua , Sulchek Todd , Alexeev Alexander
Published: April 2023

Sorting biological cells in heterogeneous cell populations is a critical task required in a variety of biomedical applications and therapeutics. Microfluidic methods are a promising pathway toward establishing label-free sorting based on cell intrinsic biophysical properties, such as cell size and compliance. Experiments and numerical studies show that microchannels decorated with diagonal ridges can be used to separate cell by stiffness in a Newtonian fluid. Here, we use computational modeling to probe stiffness-based cell sorting in ridged microchannels with a power-law shear thinning fluid. We consider compliant cells with a range of elasticities and examine the effects of ridge geometry on cell trajectories in microchannel with shear thinning fluid. The results reveal that shear thinning fluids can significantly enhance the resolution of stiffness-based cell sorting compared to Newtonian fluids. We explain the mechanism leading to the enhanced sorting in terms of hydrodynamic forces acting on cells during their interactions with the microchannel ridges.
Room-temperature antiferromagnetic CrSe monolayer with tunable metal–insulator transition in ferroelectric heterostructures
Authors: Ni Xiao-Sheng , Zhang Yue-Yu , Yao Dao-Xin , Hou Yusheng
Published: April 2023

Recently, there has been a rapidly growing interest in two-dimensional (2D) transition metal chalcogenide monolayers (MLs) due to their unique magnetic and electronic properties. By using an evolutionary algorithm and first-principles calculations, we report the discovery of a previously unexplored, chemically, energetically, and thermodynamically stable 2D antiferromagnetic (AFM) CrSe ML with a Néel temperature higher than room temperature. Remarkably, we predict an electric field-controllable metal–insulator transition in a van der Waals heterostructure comprised of CrSe ML and ferroelectric Sc2CO2. This tunable transition in the CrSe/Sc2CO2 heterostructure is attributed to the change in the band alignment between CrSe and Sc2CO2 caused by the ferroelectric polarization reversal in Sc2CO2. Our findings suggest that 2D AFM CrSe ML has important potential applications in AFM spintronics, particularly in the gate voltage conducting channel.
Chiral spectral singularities spawning from quasi-bound states in the continuum in PT-symmetric dielectric metasurfaces
Authors: Chen Xiaolin , Chu Yiqi , Chen Kai , Zhang Kai , Wang Xian , Luo Qiaoxia , Zhou Yong , Ma Xiaohui , Fang Wentan , Zhang Wei , Huang Song , Gao Weiqing
Published: April 2023

We investigate the chiral spectral singularities, i.e., laser threshold modes, in PT-symmetric dielectric metasurfaces originating from quasi-bound states in the continuum. The poles, referred to as the quasi-bound states in the continuum, of scattering matrix can move to the upper complex frequency plane from the lower half-plane by increasing the balanced gain and loss. The maximal intrinsic optical chirality of laser threshold mode has been theoretically demonstrated via the large transmission circular dichroism spectra. Our work paves the way for studying the enhanced optical chirality in non-Hermitian nanophotonics empowered by quasi-bound states in the continuum, together with various intriguing applications, such as chiral coherent perfect absorber and laser.
Gender in human phonation: Fluid–structure interaction and vocal fold morphology
Authors: McCollum Isabella , Throop Alexis , Badr Durwash , Zakerzadeh Rana
Published: April 2023

This paper aims to examine the effects of variations in the vocal fold (VF) morphological features associated with gender on glottal aerodynamics and tissue deformation. Nine three-dimensional geometries of the VFs in the larynx are created with various VF lengths, thicknesses, and depths to perform a parametric analysis according to gender-related geometrical parameters. The computational model is incorporated in a fluid–structure interaction methodology by adopting the transient Navier–Stokes equations to model airflow through the larynx and considering a linear elasticity model for VF dynamics. The model predictions, such as aerodynamic data through the larynx, glottal airflow, and VF deformations, are analyzed. The comparison of the simulation results for the nine cases supports the hypothesis that gender differences in laryngeal dimensions remarkably influence the glottal airflow and deformation of the VFs. Decreasing VF thickness and increasing its length corresponds to a noticeable increase in maximum tissue displacement, while variations in depth affect the flow rate significantly in the small and large larynges. Conversely, we observed that the pressure drop at the glottis is nearly independent of the VF length. A comparison of the glottal area with published imaging data illustrated a direct correlation between the glottal configuration and the morphology of the VFs.
Wide-angle, dual-polarized frequency selective rasorber based on the electric field coupled resonator using characteristic mode analysis
Authors: Malekara Asal , Khalilzadegan Amin , Ghobadi Changiz , Nourinia Javad
Published: April 2023

A wide-angle, dual-polarized frequency selective rasorber (FSR) with two absorption bands located at both sides of a passband is proposed. The structure comprises a lossy frequency selective surface (FSS), a bandpass FSS, and an air spacer located in between. A modified electric field coupled (ELC) resonator is used as a parallel resonance at the lossy layer to achieve a passband within the absorption band. The characteristic mode theory is utilized to investigate the absorption behavior of the lossy layer. Extensive simulations were carried out to assess the performance of the presented structure. Under the normal incidence, the proposed structure provides an operating bandwidth (|S11| < −10 dB) from 1.94 to 7.16 GHz, corresponding to a fractional bandwidth (FBW) of 114.7%. The achieved passband is around 4.3 GHz with a minimum insertion loss of 0.81 dB. The absorption bands with an absorption rate higher than 80% are 1.81–3.69 GHz (FBW of 68.4%) in the lower band and 4.95–7.43 GHz (FBW of 40%) in the upper band, respectively. It exhibits quite stable characteristics up to 50° angle of incidence. Furthermore, a prototype was fabricated and measured, which confirms that a good agreement exists between the experimental and simulation results. The proposed FSR is a suitable candidate for lowering the radar cross section (RCS) of the communication equipment or making them stealthy.
Shallow defect layer formation as Cu gettering layer of ultra-thin Si chips using moderate-pressure (3.3 kPa) hydrogen plasma
Authors: Nomura Toshimitsu , Kakiuchi Hiroaki , Ohmi Hiromasa
Published: April 2023

In this study, we developed a shallow defect layer formation process using moderate-pressure H2 plasma at 3.3 kPa for an extrinsic gettering layer of ultra-thin Si chips aimed at three-dimensional integrated circuits. This process can be conducted in the presence of trivial amounts of air impurities (∼0.01 vol. %), thereby avoiding the use of high-vacuum equipment. We investigated the dependence of defect formation behavior on various processing parameters such as H2 flow rate, processing time, substrate temperature, and input power. It was determined that the absence of H2 gas flow was favorable for the defect layer formation because Si etching by hydrogen atoms was suppressed. A low Si temperature and high input power are desirable for a high defect density in the shallow surface region of the extrinsic gettering layer. When pulse-modulated plasma irradiation was attempted, the defect layer that formed became thinner and had a higher defect density than that obtained by continuous plasma, demonstrating good Cu gettering performance. Without using harmless chemicals, or high-cost equipment, a shallow gettering layer can be formed using inexpensive H2 gas.
Comparing the performance fluctuation of direct and alternating current poling Pb(In1/2Nb1/2)O3-Pb(Mg1/3Nb2/3)O3-PbTiO3 ferroelectric single crystals
Authors: Hu Yudong , Yang Xiaoming , Zhang Wenjie , Wang Zujian , Tang Haiyue , Su Rongbing , Liu Ying , Long Xifa , He Chao
Published: April 2023

Large-size Pb(Mg1/3Nb2/3)O3-PbTiO3 (PMN-PT) based ferroelectric single crystals have been grown successfully by the vertical Bridgman method for application in the field of high-end piezoelectric devices. The piezoelectric and dielectric performance uniformity of PMN-PT based ferroelectric crystals is a critical application requirement. Recently, alternating current poling (ACP) has attracted much attention due to its low cost and high efficiency in improving the piezoelectric properties of PMN-PT based crystals. Here, we report the comparison of the performance fluctuation of direct current poling (DCP) and ACP Pb(In1/2Nb1/2)O3-Pb(Mg1/3Nb2/3)O3-PbTiO3 (PIN-PMN-PT) ferroelectric single crystals grown in the [110] direction using the vertical Bridgman method. The fluctuation of piezoelectric coefficient d33, dielectric constant ɛT33/ɛ0, and dielectric loss tanδ was presented. We found that the average d33 and ɛT33/ɛ0 of ACP samples are 1290 and 1500 pC/N and 3890 and 4290 for two different wafers, which were 18% and 23%, 21% and 26% higher than DCP samples. The tanδ of ACP samples was much lower than that of DCP samples. The DCP and ACP samples exhibited the close data of the fluctuation ratios of d33 and ɛT33/ɛ0. The fluctuation ratios of d33 and ɛT33/ɛ0 for DCP and ACP samples are all less than 10%. This work offers a reference for practical ACP technique applications.
Diffusion growth mechanism of penta-twinned Ag nanocrystals from decahedral seeds
Authors: Cui Jianming , Phul Saksham , Fichthorn Kristen A.
Published: April 2023

Crystals with penta-twinned structures can be produced from diverse fcc metals, but the mechanisms that control the final product shapes are still not well understood. By using the theory of absorbing Markov chains to account for the growth of penta-twinned decahedral seeds via atom deposition and surface diffusion, we predicted the formation of various types of products: decahedra, nanorods, and nanowires. We showed that the type of product depends on the morphology of the seed and that small differences between various seed morphologies can lead to significantly different products. For the case of uncapped decahedra seeds, we compared predictions from our model to nanowire morphologies obtained in two different experiments and obtained favorable agreement. Possible extensions of our model are indicated.
Dynamics of hybrid magnetic skyrmion driven by spin–orbit torque in ferrimagnets
Authors: Liu Y. , Liu T. T. , Hou Z. P. , Chen D. Y. , Fan Z. , Zeng M. , Lu X. B. , Gao X. S. , Qin M. H. , Liu J.-M.
Published: April 2023

Precise control of skyrmion dynamics is essential for the future spintronic device design based on the magnetic skyrmions. In this work, we propose a scheme to implement hybrid magnetic skyrmions (HMS) in ferrimagnets and we study the dynamics of the HMS driven by spin–orbit torque. It is revealed that the skyrmion Hall effect depends on the skyrmion helicity and the net angular momentum (δs), allowing the effective modulation of the HMS motion through tuning Dzyaloshinskii–Moriya interaction and δs. Moreover, the Magnus force for finite δs suppresses the transverse motion and enhances the longitudinal propagation, resulting in the decrease in Hall angle accompanying faster dynamics than that in antiferromagnets. Thus, the Hall effect can be suppressed through selecting suitable materials to better control the HMS motion. Finally, we propose a convenient skyrmion diversion scheme through modulating the helicity and Hall angle of the HMS, benefiting the future spintronic device design.
Effect of in-situ SiNx grown with different carrier gas on structural and electrical properties of GaN-based MISHEMTs
Authors: Zhang Haochen , Chen Yao , Sun Yue , Yang Lei , Hu Kunpeng , Huang Zhe , Liang Kun , Xing Zhanyong , Wang Hu , Zhang Mingshuo , Guo Shiping , Sun Haiding
Published: April 2023

In this work, the effect of in situ SiNx grown with different carrier gas on the structural and electrical properties of the SiNx/AlGaN/GaN MIS-HEMTs is studied. It was found that the growth rate of SiNx grown with N2 as carrier gas (N2-SiNx) is more sensitive to different growth conditions, while the growth rate of SiNx grown with H2 as carrier gas (H2-SiNx) is very stable due to the inhibiting effects of H2 carrier gas on the SiH4–NH3 forward reactions. More importantly, a continuous and smooth SiNx growth at the initial stage can be realized with H2 carrier gas due to its faster surface migration, leading to a decent surface morphology and sharp interface of H2-SiNx. As a result, the SiNx passivated device with H2 as carrier gas shows improved performance compared to that with N2 as carrier gas, featuring ultra-low interface-state density of 2.8 × 1010 cm−2 eV−1, improved on- and off-state current, reduced threshold voltage shift, and mitigated current collapse, especially after long-term electrical stress. These results not only elaborate on the growth mechanisms of in situ SiNx with different carrier gases but also highlight the advances of H2 as carrier gas for in situ SiNx growth, providing an effective strategy to tailor the passivation schemes for GaN-based devices.
Terahertz emission from transient currents and coherent phonons in layered MoSe2 and WSe2
Authors: Afalla Jessica , Muldera Joselito , Takamizawa Semmi , Fukuda Takumi , Ueno Keiji , Tani Masahiko , Hase Muneaki
Published: April 2023

Terahertz (THz) time-domain emission spectroscopy was performed on layered 2H-MoSe 2 and 2H-WSe 2. The THz emission shows an initial cycle attributed to surge currents and is followed by oscillations attributed to coherent interlayer phonon modes. To obtain the frequencies of the interlayer vibrations, an analysis of the THz emission waveforms was performed, separating the two contributions to the total waveform. Results of the fitting show several vibrational modes in the range of 5.87–32.75 cm − 1 for the samples, attributed to infrared-active interlayer shear and breathing modes. This study demonstrates that THz emission spectroscopy provides a means of observing these low-frequency vibrational modes in layered materials.
Particle and guiding-center orbits in crossed electric and magnetic fields
Authors: Brizard Alain J.
Published: April 2023

The problem of the charged-particle motion in crossed electric and magnetic fields is investigated, and the validity of the guiding-center representation is assessed in comparison with the exact particle dynamics. While the magnetic field is considered to be straight and uniform, the (perpendicular) radial electric field is nonuniform. The Hamiltonian guiding-center theory of charged-particle motion is presented for arbitrary radial electric fields, and explicit examples are provided for the case of a linear radial electric field.
Strain and strain gradient engineering in membranes of quantum materials
Authors: Du Dongxue , Hu Jiamian , Kawasaki Jason K.
Published: April 2023

Strain is powerful for discovery and manipulation of new phases of matter; however, elastic strains accessible to epitaxial films and bulk crystals are typically limited to small (<2%), uniform, and often discrete values. This Perspective highlights emerging directions for strain and strain gradient engineering in free-standing single-crystalline membranes of quantum materials. Membranes enable large (∼10%), continuously tunable strains and strain gradients via bending and rippling. Moreover, strain gradients break inversion symmetry to activate polar distortions, ferroelectricity, chiral spin textures, superconductivity, and topological states. Recent advances in membrane synthesis by remote epitaxy and sacrificial etch layers enable extreme strains in transition metal oxides, intermetallics, and Heusler compounds, expanding beyond the natively van der Waals (vdW) materials like graphene. We highlight emerging opportunities and challenges for strain and strain gradient engineering in membranes of non-vdW materials.
Scenarios for a post-COVID-19 world airline network
Authors: Ye Jiachen , Ji Peng , Barthelemy Marc
Published: April 2023

The airline industry was severely hit by the COVID-19 crisis with an average demand decrease of about 64 % (IATA, April 2020), which triggered already several bankruptcies of airline companies all over the world. While the robustness of the world airline network (WAN) was mostly studied as a homogeneous network, we introduce a new tool for analyzing the impact of a company failure: the “airline company network” where two airlines are connected if they share at least one route segment. Using this tool, we observe that the failure of companies well connected with others has the largest impact on the connectivity of the WAN. We then explore how the global demand reduction affects airlines differently and provide an analysis of different scenarios if it stays low and does not come back to its pre-crisis level. Using traffic data from the Official Aviation Guide and simple assumptions about customer’s airline choice strategies, we find that the local effective demand can be much lower than the average one, especially for companies that are not monopolistic and share their segments with larger companies. Even if the average demand comes back to 60 % of the total capacity, we find that between 46 % and 59 % of the companies could experience a reduction of more than 50 % of their traffic, depending on the type of competitive advantage that drives customer’s airline choice. These results highlight how the complex competitive structure of the WAN weakens its robustness when facing such a large crisis.
Pressure-tunable magnetic topological phases in magnetic topological insulator MnSb4Te7
Authors: Gao Lingling , Wu Juefei , Xi Ming , Pei Cuiying , Wang Qi , Zhao Yi , Tian Shangjie , Li Changhua , Cao Weizheng , Chen Yulin , Lei Hechang , Qi Yanpeng
Published: April 2023

Magnetic topological insulators (TIs), possessing both magnetic order and topological electronic structure, provides an excellent platform to research unusual physical properties. Here, we report a high-pressure study on the anomalous Hall effect of magnetic TI MnSb4Te7 through transports measurements combined with first-principle theoretical calculations. We discover that the ground state of MnSb4Te7 experiences a magnetic phase transition from the A-type antiferromagnetic state to ferromagnetic dominating state at 3.78 GPa, although its crystal sustains a rhombohedral phase under high pressures. The anomalous Hall conductance σxyA is dominated by intrinsic mechanism even after the magnetic phase transition. The results shed light on the intriguing magnetism in MnSb4Te7 and pave the way for further studies of the relationship between topology and magnetism in topological materials.
A low-frequency, high-amplitude, torsional oscillator for studies of quantum fluids and solids
Authors: Guénault Anthony M. , McClintock Peter V. E. , Poole Malcolm , Schanen Roch , Tsepelin Viktor , Zmeev Dmitry E. , Schmoranzer David , Vinen William F. (“Joe”) , Garg Deepak , Devi Kalpana
Published: April 2023

We introduce a low-frequency torsional oscillator suitable for studies of quantum fluids and solids. It operates at frequencies of ∼100 Hz, achieves velocities of several cm s−1, and exhibits a quality factor of Q≃3×104. In order to reach such velocities at this relatively low frequency, the oscillator amplitude must exceed 100 μm, which would be impracticable for a conventional capacitor-driven device where the drive is applied parallel to the main motion and there are correspondingly large changes in the separation of the capacitor plates. For the different geometry of the oscillator that we now describe, however, the separations of both the drive and detect capacitor plates remain constant regardless of the amplitude of oscillation. We discuss its design and report our initial tests of its performance.
Nonreciprocal critical current in an obliquely ion-irradiated YBa2Cu3O7 film
Authors: Matsui H. , Nishijima G. , Matsumoto A. , Yamaguchi I. , Manabe T. , Sohma M.
Published: April 2023

We observed a superconducting diode effect (SDE) at 77 K in a YBa2Cu3O7 (YBCO) film irradiated with 75-MeV-Au ions directed 30°-off normal to the film surface. Up to 3% asymmetry in dc critical-current appeared remarkably in out-of-plane magnetic fields. In this field orientation, a conventional SDE does not emerge due to an asymmetric barrier to vortex entry between the film surface and the film–substrate interface. We also observed a sudden reversal of the diode polarity when the magnetic-field-angle was rotated across the ion-incident-angle. Our results indicate an unconventional SDE in YBCO films that include tilted 1D defects.
Comparing semiclassical mean-field and 1-exciton approximations in evaluating optical response under strong light–matter coupling conditions
Authors: Cui Bingyu , Sukharev Maxim , Nitzan Abraham
Published: April 2023

The rigorous quantum mechanical description of the collective interaction of many molecules with the radiation field is usually considered numerically intractable, and approximation schemes must be employed. Standard spectroscopy usually contains some levels of perturbation theory, but under strong coupling conditions, other approximations are used. A common approximation is the 1-exciton model in which processes involving weak excitations are described using a basis comprising the ground state and singly excited states of the molecule cavity-mode system. In another frequently used approximation in numerical investigations, the electromagnetic field is described classically, and the quantum molecular subsystem is treated in the mean-field Hartree approximation with its wavefunction assumed to be a product of single molecules’ wavefunctions. The former disregards states that take long time to populate and is, therefore, essentially a short time approximation. The latter is not limited in this way, but by its nature, disregards some intermolecular and molecule-field correlations. In this work, we directly compare results obtained from these approximations when applied to several prototype problems involving the optical response of molecules-in-optical cavities systems. In particular, we show that our recent model investigation [J. Chem. Phys. 157, 114108 (2022)] of the interplay between the electronic strong coupling and molecular nuclear dynamics using the truncated 1-exciton approximation agrees very well with the semiclassical mean-field calculation.
Solution-processed small-molecular organic memristor with a very low resistive switching set voltage of 0.38 V
Authors: Wen Xuemiao , Tang Wenwei , Lin Zhenkun , Peng Xiaobin , Tang Zhenfang , Hou Lintao
Published: April 2023

Organic memristors are considered to be the next-generation storage element due to their unique advantages of flexibility, transparency, and good solution processability. In this Letter, a Zn-porphyrin based small-molecular organic memristor is prepared by spin-coating with an ultralow resistive switching set voltage of 0.38 V. It is found that the zinc atom in the porphyrin molecule plays a very important role in improving the resistance switching characteristics of organic memristors. By tracking the change in oxygen valence in the vertical dimension, we demonstrate that Zn atom located in the core of porphyrin helps to enhance the oxygen ion migration across the active layer, clearly revealing the memory mechanism of low-cost solution-processed Zn-porphyrin based small-molecular organic memristors. This organic memristor shows excellent memristive performance resulting from rational material design and appropriate device structure engineering.
Oblique water entry of an inclined finite plate with gravity effect
Authors: Sun Shi Yan , Wu G. X.
Published: April 2023

The hydrodynamic problem of an inclined finite plate entering into water obliquely is investigated through the velocity potential flow theory in the time domain, together with the fully nonlinear boundary conditions on the deforming free surface. A boundary element method is adopted. A stretched coordinate system method is used for the varying computational domain, which starts from a single point at the lower edge of the plate. The whole process of the flow attached on the plate and flow detached from its upper edge is considered, which may involve self-similar flow, transient flow, and steady flow. The gravity effect is also considered. Studies are further conducted for oblique water entry and varying speed entry. Extensive results are provided. Their physical implications and potential applications are discussed.
Fast particles in drift wave turbulence
Authors: Weiland J. , Rafiq T. , Schuster E.
Published: April 2023

This study aims to incorporate the effects of fast particles into our present fluid model for tokamak transport. The parameter ε f = ω / ω f, where ω is the mode frequency and ω f is the typical frequency of the fast particles, which enters as a factor in front of the fast particle response. Thus, for trapped fast particles, where ω f = ω pres the precession frequency of the fast particles, this parameter is of order 10 − 2 for drift waves, and thus, the fast particle response can be neglected. However, ε f will be of order 1 for fast particle modes such as in the fishbone instability. An important turbulence property, affecting both these limits, is resonance broadening. Effects of resonance broadening have recently been considered for fast particle instabilities, often coupled directly to the linear growth rate, while we here consider the original Dupree formulation where the turbulence directly drives a nonlinear frequency shift. Resonance broadening has a general tendency to counteract dissipative wave particle resonances. This has been observed for fast particle instabilities. Here, there is a resonant external source for the fast particles, so the instability survives if this source is dominant over the resonance broadening. For drift waves, however, external sources are not resonant since ε f ≪ 1. Thus, the resonance broadening is able to remove the dissipative wave particle resonance completely.
Comparing zero-parameter theories for the WCA and harmonic-repulsive melting lines
Authors: Dyre Jeppe C. , Pedersen Ulf R.
Published: April 2023

The melting line of the Weeks–Chandler–Andersen (WCA) system was recently determined accurately and compared to the predictions of four analytical hard-sphere approximations [Attia et al., J. Chem. Phys. 157, 034502 (2022)]. Here, we study an alternative zero-parameter prediction based on the isomorph theory, the input of which are properties at a single reference state point on the melting line. The two central assumptions made are that the harmonic-repulsive potential approximates the WCA potential and that pair collisions are uncorrelated. The new approach gives excellent predictions at high temperatures, while the hard-sphere-theory based predictions are better at lower temperatures. Supplementing the WCA investigation, the face-centered-crystal to fluid coexistence line is determined for a system of harmonic-repulsive particles and compared to the zero-parameter theories. The results indicate that the excellent isomorph-theory predictions for the WCA potential at higher temperatures may be partly due to a cancellation of errors between the two above-mentioned assumptions.
Enabling large-scale quantum path integral molecular dynamics simulations through the integration of Dcdftbmd and i-PI codes
Authors: Nishimura Yoshifumi , Nakai Hiromi
Published: April 2023

A large-scale quantum chemical calculation program, Dcdftbmd, was integrated with a Python-based advanced atomistic simulation program, i-PI. The implementation of a client–server model enabled hierarchical parallelization with respect to replicas and force evaluations. The established framework demonstrated that quantum path integral molecular dynamics simulations can be executed with high efficiency for systems consisting of a few tens of replicas and containing thousands of atoms. The application of the framework to bulk water systems, with and without an excess proton, demonstrated that nuclear quantum effects are significant for intra- and inter-molecular structural properties, including oxygen–hydrogen bond distance and radial distribution function around the hydrated excess proton.
Similarity characteristics in the morphology of radial viscous fingers
Authors: Oliveira Rafael M. , Abedi Behbood , Santos Larissa F. , Câmara Pedro S. , de Souza Mendes Paulo R.
Published: April 2023

We conduct nonlinear simulations to investigate the radial growth of viscous fingers in a Hele–Shaw cell by performing a wide parametric study on the two dimensionless parameters that govern the dynamics. These are the viscosity contrast, A, and the effective surface tension, B, which compares the influence of surface tension with the injection rate that drives instability. It is well known that the surface tension between the fluids has a stabilizing influence on pattern formation leading to slower fingering growth and a reduced number of fingers. Moreover, the current results show that, for fixed A values, larger values of the effective surface tension lead to the formation of fingering patterns that are similar to each other. As such, the calculated interfacial shapes are larger and take longer to develop. Furthermore, the calculated shapes offer a visually striking portrait of instability evolution, and comparison to our experimental measurements highlights the close resemblance between the two with a few discrepancies pointed out. Finally, we observe how changes to the initial nearly circular interface affect both the morphology of viscous fingers and the timescale for pattern formation.
Random telegraph noise in nanometer-scale CMOS transistors exposed to ionizing radiation
Authors: Bonaldo S. , Fleetwood D. M.
Published: April 2023

Nanometer-scale transistors often exhibit random telegraph noise (RTN) with high device-to-device variability. Recent experiments up to Grad total ionizing dose (TID) demonstrate stable RTN in planar bulk-Si metal-oxide-semiconductor (MOS) transistors and in Si fin field-effect transistors (FinFETs). In these cases, pre-existing defects in the ultrathin gate dielectrics dominate the device low-frequency 1/f noise (LFN). In contrast, III–V MOS devices with lower quality oxide/semiconductor interfaces show significant increases in LFN at much lower doses, due to the TID-induced activation of high densities of border traps. Aggressively scaled devices fabricated in Si gate-all-around nano-wire FET technology exhibit prominent defects leading to LFN and RTN. Increases or decreases of LFN in these devices during irradiation and annealing results primarily from the activation or passivation of border traps and interface traps.
Diamond-TiC composite with an ultrahigh Hugoniot elastic limit
Authors: Zhou Liang , He Hongliang , Zhang Hong , Li Yuanyuan , Gan Bo , He Ruiqi , Zhang Youjun , He Duanwei
Published: April 2023

The Hugoniot elastic limit (HEL) is widely adopted as an important criterion for assessing the dynamic strength of materials, representing the transition stress from elastic to plastic response prior to failure under shock compression. Nano-polycrystalline diamond currently holds the highest HEL of 208 (±14) GPa. Here, we report a diamond-TiC composite (∼11.5 wt. % TiC) showing an ultrahigh HEL of at least 195 (±3.5) GPa, which is comparable to that of nano-polycrystalline diamond. All measured velocity profiles on the diamond-TiC free surface exhibited a single-wave structure at shock pressures of 48–195 GPa. Moreover, the measured Us–Up (shock wave velocity–particle velocity) relation can be linearly fitted, indicating no elastic–plastic transition or solid–solid phase transition up to a shock pressure of 195 GPa. The diamond-TiC composite's compression ratio was similar to that of TiC but significantly higher than that of diamond. These extraordinary dynamic responses are intrinsically attributed to the unique microstructure in which diamond polycrystals are encased in a TiC matrix, providing protection against yielding. Our findings not only developed a mechanically reliable, lightweight, and high-performance armor material at low synthesis costs, but also provided new insights into the shock compression behavior of diamond composites.
Collisional excitation of C2H− by H2: New interaction potential and scattering calculations
Authors: Dumouchel Fabien , Quintas-Sánchez Ernesto , Balança Christian , Dawes Richard , Lique François , Feautrier Nicole
Published: April 2023

Interstellar anions play an important role in astrochemistry as being tracers of the physical and chemical conditions in cold molecular clouds and circumstellar gas. The local thermodynamic equilibrium is generally not fulfilled in media where anions are detected and radiative and collisional data are required to model the observed lines. The C2H− anion has not yet been detected in the interstellar medium; however, collisional data could be used for non-LTE models that would help in identifying the most intense lines. For this purpose, we have computed the first 4D potential energy surface (PES) of the C2H−–H2 complex using an explicitly correlated coupled-cluster approach. The PES is characterized by a single deep minimum with a well-depth of 924.96 cm−1. From this interaction potential, we derived excitation cross sections and rate coefficients of C2H− induced by collisions with para- and ortho-H2. The results obtained for collisions with para-H2 are compared to previous calculations performed using a 2D-PES obtained from an average over H2 rotations.
Nonlinear chiral magnonic resonators: Toward magnonic neurons
Authors: Fripp K. G. , Au Y. , Shytov A. V. , Kruglyak V. V.
Published: April 2023

We explore chiral magnonic resonators as building blocks of artificial neural networks. Via micromagnetic simulations and analytical modeling, we demonstrate that the spin-wave modes confined in the resonators exhibit a strongly nonlinear response owing to energy concentration when resonantly excited by incoming spin waves. This effect may be harnessed to implement an artificial neuron in a network. Therefore, the confined and propagating spin-wave modes can serve as neurons and interneural connections, respectively. For modest excitation levels, the effect can be described in terms of a nonlinear shift of the resonant frequency (“detuning”), which results in amplitude-dependent transmission of monochromatic spin waves, which may be harnessed to recreate a “sigmoid-like” activation function. At even stronger excitation levels, the nonlinearity leads to bistability and hysteresis, akin to those occurring in nonlinear oscillators when the excitation strength exceeds a threshold set by the decay rate of the mode. In magnonic resonators, the latter includes both the Gilbert damping and the radiative decay due to the coupling with the medium. The results of our simulations are well described by a phenomenological model in which the nonlinear detuning of the confined mode is quadratic in its amplitude, while the propagation in the medium is linear.
On the spontaneous symmetry breaking of eastward propagating dipoles
Authors: Davies J. , Sutyrin G. G. , Berloff P.
Published: April 2023

The spontaneous symmetry breaking of weak eastward propagating dipoles is revealed from high-resolution numerical simulations in an equivalent-barotropic quasigeostrophic beta-plane model. The evolution of initialized Larichev–Reznik dipoles is found to depend on the initial intensity, characterized by the dipole drift speed divided by the maximum Rossby wave phase speed. We found that weak dipoles lose symmetry and eventually disintegrate due to growing perturbations. This instability is attributed to a critical, linear growing mode that is extracted from the potential vorticity anomaly. The growth rate of perturbations is found to decrease with the increasing dipole intensity.
An anecdotal observation of an amputee sawfish recapture and development of safe release guide for Papua New Guinea gillnet fisheries
Authors: Grant Michael I. , Amepou Yolarnie , Chin Andrew , Hill Sarah J. , Maggacis Dana , Green Madeline
Published: April 2023

Papua New Guinea has been identified as a sawfish ‘stronghold’ nation, however, sawfish are threatened by gillnet fishers who often amputate the rostrum to assist in dis-entanglement. Here, we describe an account of a recapture of an emaciated amputee sawfish. We also present a sawfish safe release guide, developed for the small-scale fishery context of Papua New Guinea.
Can we benchmark annual ground cover maintenance?
Authors: Beutel Terrence S. , Graz F. Patrick
Published: April 2023

The capacity for rangeland stakeholders, including land managers, financiers and regulators, to regularly assess impacts of management practices on grazed landscapes has potential benefits. This paper describes the development of ground cover maintenance (GCM) spatial layers for a large study area in the catchment of the Great Barrier Reef in Queensland, Australia. GCM layers are an experimental product designed to benchmark the direction and strength of annual change in remotely sensed total ground cover (ΔTGC). This was achieved by predicting ΔTGC per pixel in a multivariate model, then using the quantile of the observed ΔTGC within its modelled prediction interval to benchmark observed ΔTGC. Under this approach, pixels with higher quantiles are those with a more positive annual observed ΔTGC after rainfall and other predictors in the multivariate model are taken into account. We then mapped these quantiles annually (2011–2021) across the study area and the annual spatial distribution of these quantiles is what we call the GCM layers. We identified two important issues to be addressed in future iterations of this work, namely, the potentially confounding impact of fire on GCM layers and their interpretation, and a need for more predictive skill in the underlying random forest model. Because management variables were not part of the underlying multivariate model but management practices can affect ΔTGC, we were interested in whether patterns in the mapped GCM values correlated with any known management practices or management-practice effects in the study area. We tested this idea on three datasets. In one, we compared GCM values from 12 well managed and 12 poorly managed grazing sites, finding no significant differences between the two groups. Another analysis looked at the relationship between grazing land condition and cumulative GCM values at two sets of sites (n = 110 and n = 189). Land condition and cumulative GCM values correlated significantly, although in only one of these data sets. Overall, we conclude that the developed GCM layers require further refinement to fit their desired purpose, but have potential to produce a number of benefits if current limitations can be addressed.
M
1
-selective muscarinic allosteric modulation enhances cognitive flexibility and effective salience in nonhuman primates
Authors: Hassani Seyed A. , Neumann Adam , Russell Jason , Jones Carrie K. , Womelsdorf Thilo
Published: April 2023

Acetylcholine (ACh) in cortical neural circuits mediates how selective attention is sustained in the presence of distractors and how flexible cognition adjusts to changing task demands. The cognitive domains of attention and cognitive flexibility might be differentially supported by the M
1
muscarinic acetylcholine receptor (mAChR) subtype. Understanding how M
1
mAChR mechanisms support these cognitive subdomains is of highest importance for advancing novel drug treatments for conditions with altered attention and reduced cognitive control including Alzheimer’s disease or schizophrenia. Here, we tested this question by assessing how the subtype-selective M
1
mAChR positive allosteric modulator (PAM) VU0453595 affects visual search and flexible reward learning in nonhuman primates. We found that allosteric potentiation of M
1
mAChRs enhanced flexible learning performance by improving extradimensional set shifting, reducing latent inhibition from previously experienced distractors and reducing response perseveration in the absence of adverse side effects. These procognitive effects occurred in the absence of apparent changes of attentional performance during visual search. In contrast, nonselective ACh modulation using the acetylcholinesterase inhibitor (AChEI) donepezil improved attention during visual search at doses that did not alter cognitive flexibility and that already triggered gastrointestinal cholinergic side effects. These findings illustrate that M
1
mAChR positive allosteric modulation enhances cognitive flexibility without affecting attentional filtering of distraction, consistent with M
1
activity boosting the effective salience of relevant over irrelevant objects specifically during learning. These results suggest that M
1
PAMs are versatile compounds for enhancing cognitive flexibility in disorders spanning schizophrenia and Alzheimer’s diseases.
Generalised spectral dimensions in non-perturbative quantum gravity
Authors: Reitz M , Németh D , Rajbhandari D , Görlich A , Gizbert-Studnicki J
Published: April 2023

The seemingly universal phenomenon of scale-dependent effective dimensions in non-perturbative theories of quantum gravity has been shown to be a potential source of quantum gravity phenomenology. The scale-dependent effective dimension from quantum gravity has only been considered for scalar fields. It is, however, possible that the non-manifold like structures, that are expected to appear near the Planck scale, have an effective dimension that depends on the type of field under consideration. To investigate this question, we have studied the spectral dimension associated to the Laplace–Beltrami operator generalised to k-form fields on spatial slices of the non-perturbative model of quantum gravity known as causal dynamical triangulations. We have found that the two-form, tensor and dual scalar spectral dimensions exhibit a flow between two scales at which an effective dimension appears. However, the one-form and vector spectral dimensions show only a single effective dimension. The fact that the one-form and vector spectral dimension do not show a flow of the effective dimension can potentially be related to the absence of a dispersion relation for the electromagnetic field, but dynamically generated instead of as an assumption.
Two ground-state bright solitons in fractional-order spin–orbit-coupled Bose–Einstein condensates
Authors: Bao Y Y , Li S R , Liu Y H , Xu T F
Published: April 2023

We study two types of bright solitons in zero and non-zero detuning spin–orbit-coupled (SOC) Bose–Einstein condensates in fractional effect by variational and imaginary-time evolution method. The results show that the variation of SOC with fractional kinetic energy operator affects the existence and form of solitons. In particular, we found that SOC strength

γ
=
1.0

could be a transition point. In other words, for

γ
<
1.0

and

γ
⩾
1.0

, the soliton states and pseudo-spin polarization in non-zero detuning show opposite changes. In addition, moving bright solitons with zero and non-zero detuning are studied.
Classification and identification of mixed gases based on the combination of semiconductor sensor array with SSA-BP neural network
Authors: Li Meihua , Gu Yunlong , Ge Shikun , Zhang Yunfan , Mou Chao , Zhu Huichao , Wei Guangfen
Published: April 2023

In this paper, pure

Sn

O

2

,

Cu/Sn

O

2

, ZnO and Cu/ZnO gas sensitive materials were synthesized by a simple hydrothermal reaction and used to prepare a gas sensor array. The morphological structure and composition of the synthesized materials were characterized using SEM and XRD, respectively. The sensor array was combined with the back propagation neural network algorithm optimized by the sparrow search algorithm (SSA-BPNN) and applied to effectively identify the types of mixed toxic gases in the room, including formaldehyde, ammonia and xylene. The combination of sensor array with optimized neural network algorithms achieved a good classification result for gas mixture and the classification accuracy can reach 93.45% for different classes of mixtures composed of three gases (formaldehyde, ammonia, and xylene). Therefore, the sensor array combined with the SSA-BP algorithm in this study has done a good work in the qualitative identification of ternary gas mixtures and has some application potential.
Transient dynamics of the field induced force in the isotropic magnetorheological elastomer
Authors: Kubík M , Borin D , Odenbach S
Published: April 2023

The transition dynamics in silicon rubber based isotropic magnetorheological (MR) elastomers in terms of the normal force induced by an external homogeneous magnetic field is experimentally addressed. The primary goal was to evaluate dynamic performances of the MR elastic isotropic composite using a transparently presented measuring system with known characteristics in contrast to few previous studies on the topic. It was found that an increase in the magnetic field leads to an increase in the induced force and a decrease in the response time of the MR elastomer. At the same time, both the use of coarse particles as magnetic filler and a significant reduction in the stiffness of the polymer matrix reduce the response time of the MR elastomer under study. The analysis carried out takes into account the dynamics of the electromagnetic coil and the eddy currents induced in the magnet circuit. The shortest response times obtained for various MR elastomer samples are in the range of 27–72 ms for the maximal used magnetic field with an induction of 230 mT. These times correspond to the fastest previously reported ones for MR elastomers and MR elastomer based systems. In addition, the obtained results indicate the presence of different mechanisms responsible for the measured magnetodeformational effect observed in MR elastomers.