bluuebunny/crossref_metadata_2025 huggingface dataset:
Correct estimation of permeability using experiment and simulation
Authors: Khirevich Siarhei , Yutkin Maxim , Patzek Tadeusz W.
Published: December 2022

Estimation of permeability of porous media dates back to Henry Darcy [H. Darcy, Les Fontaines Publiques de la Ville de Dijon (Victor Dalmont, 1856)], and its knowledge is essential in many scientific and engineering endeavors. Despite apparent simplicity of permeability measurements, the literature data are scattered, and this scatter not always can be attributed to the precision of experiment or simulation or to sample variability. Here, we demonstrate an excellent agreement (<1%) between experiments and simulations, where experimental results are extensive and stable, while flow is simulated from first principles, directly on three-dimensional images of the sample, and without fitting parameters. Analyzing when experiments and simulations agree reveals a major flaw affecting many experimental measurements with the out-of-sample placement of pressure ports, including industry standards. The flaw originates from (1) incorrect calculation of the applied pressure gradient, (2) omitting virtual part of the measured system, and (3) pressure loss at the sample–tube contact. Contrary to common wisdom, the relative magnitude of (3) is defined by the sample–tube diameter ratio and is independent of the size of sample pores. Our findings are applicable to a wide range of permeability measurements, including geological-sample-type (Hassler cell) and membrane-type. The reported pressure loss (3) also affects two-phase flow measurements, such as capillary pressure estimation. Removing or taking the flaw into account advances the understanding and control of flow-related processes in complex geometries.
Quasi-periodic and chaotic structure of Alfvén waves in a plasma containing double spectral distributed electrons
Authors: El-Labany S. K. , El-Taibany W. F. , El-Tantawy A. A. , Abdelghany A. M.
Published: December 2022

The nonlinear characteristics of Alfvén waves in a plasma medium composed of double spectral electron distribution and positive and negative ions are investigated. A Korteweg–de Vries (KdV-type) equation is derived using the reductive perturbation technique. The periodic and soliton structures are investigated. The effects of the two spectral indices r and q on the produced periodic structures are studied. It is found that the amplitude of the rarefactive periodic wave increases by increasing the values of r and q. Some external perturbation intruders on the system are considered, and the quasi periodic and chaotic structures of Alfvén waves are discussed. It is found that by decreasing the values of β− (knowing that β known as the ratio of kinetic to magnetic pressures), the periodic structure is converted gradually into chaotic structure passing through the quasi-periodic one. The results of this study are helpful in describing the behavior of the Alfvénic structure of periodic waves and other related events in the ionosphere region.
Acceleration of polytropic solar wind: Parker Solar Probe observation and one-dimensional model
Authors: Shi Chen , Velli Marco , Bale Stuart D. , Réville Victor , Maksimović Milan , Dakeyo Jean-Baptiste
Published: December 2022

The acceleration of the solar coronal plasma to supersonic speeds is one of the most fundamental yet unresolved problems in heliophysics. Despite the success of Parker's pioneering theory on an isothermal solar corona, the realistic solar wind is observed to be non-isothermal, and the decay of its temperature with radial distance usually can be fitted to a polytropic model. In this work, we use Parker Solar Probe data from the first nine encounters to estimate the polytropic index of solar wind protons. The estimated polytropic index varies roughly between 1.25 and 1.5 and depends strongly on solar wind speed, faster solar wind on average displaying a smaller polytropic index. We comprehensively analyze the 1D spherically symmetric solar wind model with the polytropic index γ∈[1,5/3]. We derive a closed algebraic equation set for transonic stellar flows, that is, flows that pass the sound point smoothly. We show that an accelerating wind solution only exists in the parameter space bounded by C0/Cg<1 and (C0/Cg)2>2(γ−1), where C0 and Cg are the surface sound speed and one half of the escape velocity of the star, and no stellar wind exists for γ>3/2. With realistic solar coronal temperatures, the observed solar wind with γ≳1.25 cannot be explained by the simple polytropic model. We show that mechanisms such as strong heating in the lower corona that leads to a thick isothermal layer around the Sun and large-amplitude Alfvén wave pressure are necessary to remove the constraint in γ and accelerate the solar wind to high speeds.
Broadband infrared confocal imaging for applications in additive manufacturing
Authors: Curry Erin B. , Lyszak Kaitlin C. , Sheets Donal , Gorman Lauren M. , Hebert Rainer J. , Hancock Jason N.
Published: December 2022

We address new measurement challenges relating to 3D printing in metal powder using the powder bed fusion technique. Using a combination of confocal microscopy principles and fast, sensitive mid-infrared collection techniques, we present a compact and versatile method of measuring and analyzing broadband thermal emissions from the vicinity of the molten metal pool during the additive manufacturing process. We demonstrate the benefits of this instrumentation and potential for scientific research as well as in situ monitoring. Our compact microscope collection optics can be implemented in various powder bed fusion machines under vacuum or inert atmospheric environments to enable extensions such as multi-color pyrometry or spectroscopic studies of additive manufacturing processes.
Scalable large-area mesh-structured microfluidic gradient generator for drug testing applications
Authors: Yadav Shital , Tawade Pratik , Bachal Ketaki , Rakshe Makrand A. , Pundlik Yash , Gandhi Prasanna S. , Majumder Abhijit
Published: December 2022

Microfluidic concentration gradient generators are useful in drug testing, drug screening, and other cellular applications to avoid manual errors, save time, and labor. However, expensive fabrication techniques make such devices prohibitively costly. Here, in the present work, we developed a microfluidic concentration gradient generator (μCGG) using a recently proposed non-conventional photolithography-less method. In this method, ceramic suspension fluid was shaped into a square mesh by controlling Saffman Taylor instability in a multiport lifted Hele–Shaw cell (MLHSC). Using the shaped ceramic structure as the template, μCGG was prepared by soft lithography. The concentration gradient was characterized and effect of the flow rates was studied using COMSOL simulations. The simulation result was further validated by creating a fluorescein dye (fluorescein isothiocanate) gradient in the fabricated μCGG. To demonstrate the use of this device for drug testing, we created various concentrations of an anticancer drug—curcumin—using the device and determined its inhibitory concentration on cervical cancer cell-line HeLa. We found that the IC50 of curcumin for HeLa matched well with the conventional multi-well drug testing method. This method of μCGG fabrication has multiple advantages over conventional photolithography such as: (i) the channel layout and inlet-outlet arrangements can be changed by simply wiping the ceramic fluid before it solidifies, (ii) it is cost effective, (iii) large area patterning is easily achievable, and (iv) the method is scalable. This technique can be utilized to achieve a broad range of concentration gradient to be used for various biological and non-biological applications.
A memristor based on two-dimensional MoSe2/MoS2 heterojunction for synaptic device application
Authors: Liu Ping , Luo Huiming , Yin Xiaomiao , Wang Xingfu , He Xuemin , Zhu Jiangwei , Xue Hongtao , Mao Weiwei , Pu Yong
Published: December 2022

Two-dimensional materials are promising for exploring memristors with excellent performance. However, the memristor still faces challenges in insufficient reliability due to resistance-switching mechanisms of conductive filaments. In this work, a typical metal/heterojunction/metal structure (Ag/MoSe2/MoS2/Au/Ti) was proposed as the device architecture of the memristor. The device exhibits stable bipolar resistive switching behavior with a high on–off ratio, long retention time, and good endurance. The resistance-switching is achieved by adjusting the interface barrier of the MoSe2/MoS2 due to the band modulation. Moreover, we explore the essential synaptic functions of this memristor device, with outstanding voltage pulse potentiation and depression. Our work highlights the significant prospects of MoSe2/MoS2 heterojunction in artificial synapses and neural networks.
Experimental and numerical investigation of bistability in rotating permanent magnet-generated electrolyte flow in a ring-shaped container
Authors: Berenis D. , Grants I.
Published: December 2022

Here, the stability of a transversely magnetized rotating permanent magnet-generated flow in a concentric cylindrical ring channel is studied. Numerical calculations show that the steady-state solution becomes asymmetric through a pitchfork bifurcation at a Reynolds number (Re) of 60. The two new antisymmetric steady-state solutions become cyclic at Re = 90. Nonlinearities develop at larger Re values and the limit cycle solutions are destabilized at Re = 250, enabling random transition events between the two pitchfork branches. Such transitions have been observed in all kinds of natural phenomena, spanning from neuroscientific to astrophysical systems, which are often too complex to be directly computed. Our presented system is physical yet simple enough to be used to conduct a parametric study with full three-dimensional direct numerical simulations. It raises the possibility of numerically and experimentally analyzing transitions in more detail. Experimental measurements indicated the existence of long-lived states and suitability for the proposed system for future studies of such phenomenon. However, the experimental results did not conclusively observe bistability.
An analysis of bi-directional Stokes micropump comprising a periodic array of moving belts
Authors: Lei Jie-Chao , Chang Chien-Cheng , Wang Chang-Yi
Published: December 2022

In this study, we present an analysis of a Stokes micropump comprising a periodic array of parallel finite belts moved by rotating shafts. The geometry of the mechanical micropump is uniquely determined by the ratio of the length of the belts to the width between two neighboring belts (i.e., the aspect ratio a). The method of eigenfunction expansions with collocation is applied to solve the Stokes equation for the pumping rate, the stream function, and the velocity field as well as for the pressure gradient, which are all normalized by proper scales. It is found that with increasing a, the normalized pumping rate per unit micropump (or, simply abbreviated as a unit channel) first increases drastically and then decreases exponentially until it becomes a constant for large a, indicating that there exists a critical aspect ratio (ac = 0.035) at which the maximum pumping rate (qmax = 0.861) occurs, while the limiting value of q at large a is 0.5. The steady flow is driven by the moving belts against the established pressure gradient, and the pressure gradient at the centerline reaches its maximum value at the channel center and vanishes at distances from the micropump. Moreover, it is shown that the average flow velocity component perpendicular to the moving direction of the belts is relatively small, so that the flow field in the channel is approximately a unidirectional laminar flow, and therefore, the results are not necessarily limited to very low Reynolds numbers.
Extreme transient dynamics
Authors: Dudkowski Dawid , Jaros Patrycja , Kapitaniak Tomasz
Published: December 2022

We study the extreme transient dynamics of four self-excited pendula coupled via the movable beam. A slight difference in the pendula lengths induces the appearance of traveling phase behavior, within which the oscillators synchronize, but the phases between the nodes change in time. We discuss various scenarios of traveling states (involving different pendula) and their properties, comparing them with classical synchronization patterns of phase-locking. The research investigates the problem of transient dynamics preceding the stabilization of the network on a final synchronous attractor, showing that the width of transient windows can become extremely long. The relation between the behavior of the system within the transient regime and its initial conditions is examined and described. Our results include both identical and non-identical pendula masses, showing that the distribution of the latter ones is related to the transients. The research performed in this paper underlines possible transient problems occurring during the analysis of the systems when the slow evolution of the dynamics can be misinterpreted as the final behavior.
Multiscale multiphase flow simulations using interface capturing and Lagrangian particle tracking
Authors: Li Linmin , Jiang Bowen , Wei Guolai , Li Xiaojun , Zhu Zuchao
Published: December 2022

Numerical simulations of multiphase flows with both interfaces and discrete particles are challenging because they possess a wide range of length and time scales. Meanwhile, the volume of fluid (VOF) method is suitable for resolving the interface, while the discrete particle model (DPM) under the Lagrangian frame better simulates unresolvable particles; a multiscale VOF–DPM combined model is urgently needed for multiscale multiphase flows. The present work implements a VOF–DPM solver that includes a two-way transition algorithm to model the transformation between discrete and continuous phases for bubbles or droplets using OpenFOAM. The interface-capturing scheme in the solver is based on the interIsoFoam solver, which supports the geometric reconstruction of the interface and adaptive mesh refinement. A connected component labeling approach is used for particle detection and VOF-to-DPM transition for discrete bubbles or droplets produced by interface breakup. Conversely, a DPM-to-VOF transition algorithm for particles touching the interface is incorporated to achieve a two-way transition. In addition, phase change modeling between continuous phases and bubble dynamic modeling for cavitating flow cases are also implemented in the solver. Test simulations are performed for validation, including the gas–liquid two-phase dam break and cavitating flow in a convergent–divergent test section. The results demonstrate that the solver is reasonably accurate and can adequately represent the complex phase structure, including the interface and discrete particles.
Mapping the self-generated magnetic fields due to thermal Weibel instability
Authors: Zhang Chaojie , Wu Yipeng , Sinclair Mitchell , Farrell Audrey , Marsh Kenneth A. , Petrushina Irina , Vafaei-Najafabadi Navid , Gaikwad Apurva , Kupfer Rotem , Kusche Karl , Fedurin Mikhail , Pogorelsky Igor , Polyanskiy Mikhail , Huang Chen-Kang , Hua Jianfei , Lu Wei , Mori Warren B. , Joshi Chan
Published: December 2022

The origin of the seed magnetic field that is amplified by the galactic dynamo is an open question in plasma astrophysics. Aside from primordial sources and the Biermann battery mechanism, plasma instabilities have also been proposed as a possible source of seed magnetic fields. Among them, thermal Weibel instability driven by temperature anisotropy has attracted broad interests due to its ubiquity in both laboratory and astrophysical plasmas. However, this instability has been challenging to measure in a stationary terrestrial plasma because of the difficulty in preparing such a velocity distribution. Here, we use picosecond laser ionization of hydrogen gas to initialize such an electron distribution function. We record the 2D evolution of the magnetic field associated with the Weibel instability by imaging the deflections of a relativistic electron beam with a picosecond temporal duration and show that the measured

k

-resolved growth rates of the instability validate kinetic theory. Concurrently, self-organization of microscopic plasma currents is observed to amplify the current modulation magnitude that converts up to ~1% of the plasma thermal energy into magnetic energy, thus supporting the notion that the magnetic field induced by the Weibel instability may be able to provide a seed for the galactic dynamo.
Thekopsora minima (Arthur) Syd. & Syd. [Distribution map].
Authors: CABI  , EPPO
Published: December 2022

A new distribution map is provided for Thekopsora minima (Arthur) Syd. & Syd. Pucciniomycetes: Pucciniales: Pucciniastraceae. Main hosts: blueberry (
Vaccinium corymbosum
), bilberry (
V. myrtillus
), alternate host, hemlock (mostly
Tsuga canadensis
).
Ceratocystis ficicola Kajitani & Masuya. [Distribution map].
Authors: CABI  , EPPO
Published: December 2022

A new distribution map is provided for Ceratocystis ficicola Kajitani & Masuya. Sordariomycetes: Microascales: Ceratocystidaceae. Host: fig (
Ficus carica
), Ficus benjamina.
Cotton leaf curl Gezira virus. [Distribution map].
Authors: CABI  , EPPO
Published: December 2022

A new distribution map is provided for Cotton leaf curl Gezira virus. Geminiviridae: Begomovirus. Main host: cotton (
Gossypium
spp.).
The
C∞
-isomorphism property for a class of singularly-weighted x-ray transforms
Authors: Mishra Rohit Kumar , Monard François , Zou Yuzhou
Published: December 2022

We study a one-parameter family of self-adjoint normal operators for the x-ray transform on the closed Euclidean disk

D

, obtained by considering specific singularly weighted L
2 topologies. We first recover the well-known singular value decompositions in terms of orthogonal disk (or generalized Zernike) polynomials, then prove that each such realization is an isomorphism of

C
∞

(

D

)

. As corollaries: we give some range characterizations; we show how such choices of normal operators can be expressed as functions of two distinguished differential operators. We also show that the isomorphism property also holds on a class of constant-curvature, circularly symmetric simple surfaces. These results allow to design functional contexts where normal operators built out of the x-ray transform are provably invertible, in Fréchet and Hilbert spaces encoding specific boundary behavior.
Q-switching of an optical tweezer phonon laser
Authors: Xiao Kewen , Pal Arpita , Sharma Sandeep , Pettit R M , Vamivakas A N , Bhattacharya M
Published: December 2022

We theoretically investigate the active Q-switching of an optical tweezer phonon laser Pettit et al (2019 Nat. Photon.
13 402) operating in a coupled-mode configuration. One of the modes is lasing and outcouples to the second mode. The coupling is induced via asymmetric modulation of the trap potential in the transverse plane of the trapped nanoparticle. We show that a time-modulated coherent coupling between two transverse modes of oscillation of an optically levitated nanoparticle holds the key to coherent pulsed phonon transfer between them. Our analytical and numerical results on the position dynamics, phonon dynamics as well as second-order coherence confirms pulsed phonon lasing transfer between the transverse modes. Our work on Q-switched operation of the optical tweezer phonon laser enhances understanding of the analogies between optical and mechanical lasers, and is relevant to levitated phonon transport, acoustic imaging, sensing and information processing technologies.
Numerical simulation of the ignition law for a hot bridge wire electroexplosive device
Authors: Lyu Xuxu , Wei Guanghui , Du Xue , Zhao Hongze , Sun Jiangning
Published: December 2022

Hot bridge wire electroexplosive devices (EEDs) are widely used as starting elements in aerospace and other fields. Their thermal ignition process and safety testing technology have always been a focus of research. In this paper, we construct a temperature rise model for a hot bridge wire EED by using the law of conservation of energy, and the temperature response of the bridge wire and the reagent is obtained. According to the theoretical and numerical analysis, the sensitive criterion for a hot bridge wire EED is given, and the simulation process for the critical ignition current is designed. Based on this process, the law of the influence of the bridge wire and reagent parameters on the ignition of a hot bridge wire EED was studied. The research results show that a first derivative of the reagent temperature with respect to the radial distance of greater than zero is a sensitive criterion for the ignition of a hot bridge wire EED with high accuracy. Compared with traditional numerical methods, the proposed process makes the acquisition of the critical ignition current more precise and programmable due to the use of sensitive criteria. In addition, the following significant features are noted: the critical ignition current first increases as the square root of the bridge wire radius and then linearly; the square of the critical ignition current increases linearly with the activation energy of the reagent; there is rapid exponential decay of the critical ignition current with increasing reagent combustion heat; asymptotic values are present. In engineering use, it is possible to conveniently design the ignition characteristics of a hot bridge wire EED by changing the radius of the bridge wire. This study serves as a foundational work for the safety testing of hot bridge wire EEDs and can provide theoretical guidance for the safety testing, actual production and use of hot bridge wire EEDs.
A novel ensemble convex hull-based classification model for bevel gearbox fault diagnosis
Authors: Kang Xin , Cheng Junsheng , Wang Ping , Wang Jian , Zhu Zuanyu , Yang Yu
Published: December 2022

The kernel-based geometric learning model has been successfully applied in bevel gearbox fault diagnosis. However, due to its shallow architecture and problems with its sensitivity to noise and outliers, its generalization ability and robustness need to be further improved. Ensemble learning can improve the classification accuracy of sub-classifiers, but it is effective only when the sub-classifiers meet the requirements of difference and accuracy at the same time. However, as strong classifiers, geometric learning models are difficult to produce sub-classifiers with differences. To solve these problems, this study proposes a novel ensemble model, the ensemble convex hull (CH)-based (EnCH) classification model. CH has the advantages of clear geometric meaning and is easy to deform. This paper considers the clustering characteristics of the sample points in the feature space, or both distance and density, and performs differential shrinkage deformation on the original CH. For one thing, this can produce differential CHs to build differential sub-classifiers for the ensemble. Also, it can suppress the interference of noise and outliers to improve robustness. The results of our experiments on the fault dataset of a bevel gear box indicate that the EnCH classification model can improve the generalization of the geometric learning model and has excellent tolerance to noise and outliers.
Characterisation, modelling and design of cut-off wavelength of InGaAs/GaAsSb type-II superlattice photodiodes
Authors: Petticrew Jonathan , Ji Yuting , Han Im Sik , White Benjamin , Evirgen Axel , Reverchon Jean-Luc , Hopkinson Mark , Tan Chee Hing , Ng Jo Shien
Published: December 2022

InGaAs/GaAsSb type-II superlattice (T2SL) photodiodes grown on InP substrates are an alternative detector technology for applications operating in the short wavelength infrared band. Their cut-off wavelengths are heavily influenced by the thickness and material composition of InGaAs and GaAsSb used in the T2SL. We present a single band k.p. model performed using a finite difference approach in nextnano validated against two T2SL photodiode wafers and results from literature. These photodiode wafers cover both lattice matched and strained GaAs1−x
Sb
x
compositions (x = 0.40, wafer A and 0.49, wafer B). The validation data covers temperature dependence of cut-off wavelengths (obtained from phase-sensitive photo response data) from 200 K to room temperature. The cut-off wavelengths were found to reduce at 1.32 nm K−1 for wafer A and 1.07 nm K−1 for wafer B. Good agreement was achieved between the validation data and nextnano simulations, after altering the GaAs1−x
Sb
x
valance band offset (VBO) bowing parameter to −1.06 eV. Using this validated model, we show that the wavefunction overlap drops significantly if the GaAsSb barrier is thicker than the InGaAs well layer, hence defining the upper limit of the barrier layer. This validated model is then used to demonstrate that there is a linear dependence between the maximum achievable wavefunction overlap and cut-off wavelength of a lattice matched InGaAs/GaAsSb T2SL. We also found that the adoption of a 5 nm/3 nm InGaAs/GaAsSb T2SL structure offers an improved wavefunction overlap over the more common 5 nm/5 nm InGaAs/GaAsSb T2SL designs. The data reported in this paper is available from doi: 10.15131/shef.data.20310591.
The interplay of process parameters and influence on the AlN films on sapphire fabricated by DC magnetron sputtering and annealing
Authors: Liu Huan , Guo Wei
Published: December 2022

This paper reports a high-quality aluminium nitride (AlN) film deposited on c-plane sapphire using a direct current reactive sputtering system. A comprehensive investigation on the effects of substrate temperature, sputtering power, Ar/N2 flow ratio, and process pressure on the morphology and crystalline quality of the AlN thin films was performed. Optimal process parameters including substrate temperature of 500 °C, process pressure of 0.5 Pa, gas flow ratio of Ar/N2 = 1/6, and sputtering power of 400 W was demonstrated. In addition, the crystallization quality was further improved after face-to-face annealing and homoepitaxial regrowth by metal–organic chemical vapor deposition. The full widths at half maximum values of the x-ray rocking curves of the (0002) and (

10

1
ˉ

2

) diffraction of AlN after the re-growth process reach as low as 49 and 360 arcsec, respectively, and the corresponding surface morphologies of the films were covered with atomic bi-layer steps. Finally, a ultraviolet-C light emitting diode with decent performance was demonstrated on top of the sputtered AlN thin film.
Effect of branched structure on microphase separation and electric field induced bending actuation behaviors of poly(urethane–urea) elastomers
Authors: Zeng Haibing , Fu Silian , Liang Yongri , Liu Li
Published: December 2022

Polyurethane elastomers as a type of electroactive polymers have wide applications in soft actuators, soft sensors and energy harvesting due to their high dielectric constant, high electrostriction coefficients, easy processing and structure adjustability, and superior biocompatibility etc. However, the relationship between microstructure and electromechanical properties of EAEs has not been fully understood. In this work, we fabricated the branch structured poly(urethane–urea) elastomers (PUUs) using hydroxy-terminated polybutadiene as soft segment, isophorone diisocyanate and 4,4-diaminodicyclohexylmethane as hard segment, and hydroxyl-terminated four-armed polycaprolactone (PCL410) as branch structured chain extender for improving bending actuation performances, and understanding the relationship between structure and electromechanical properties. The degree of branched structure of PUUs were adjusted by the content of PCL410. The microphase separation kinetics of PUUs was enhanced as increase of PCL410 content, whereas the degree of microphase separation and hard domain size of PUUs were reduced. The mechanical loss and bending actuation stress of PUUs were significantly improved by incorporation of small amount of branched structure into PUU chains. The PUU with 2.60 mol.% of PCL410 showed 5.16 mm of bending displacement and 5.16 Pa of bending actuation stress at 7.2 kV (corresponding to 180 V mm−1 of the nominal electric field), which were 76.3, and 79 times higher than that of PUU without PCL410, respectively. The electric field induced bending actuation mechanism of branch structured PUUs was suggested that the bending actuation mechanism of branch structured PUUs is caused by electrostrictive effect from dipole orientation induced bending deformation of constrained segments and asymmetric charge density distribution on both anode and cathode sides of PUU films. Our results can provide new insight on design novel electroactive polyurethane elastomers.
Optical fingerprints of the electronic band reconstruction in van der Waals magnetic materials
Authors: Corasaniti M , Yang R , Liu Y , Petrovic C , Degiorgi L
Published: December 2022

We report a broadband study of the charge dynamics in the van der Waals magnetic materials 2H-M

x
TaS2 (M = Mn and Co), which span the onset of both long-range antiferromagnetic (AFM) and ferromagnetic (FM) order, depending on the intercalation M and its concentration x. We discover a spectral weight (SW) shift from high to low energy scales for FM compositions, while reversely SW is removed from low towards high spectral energies for AFM compounds. This maps the related reconstruction of the electronic band structure along the crossover from the FM to AFM order, which restores an occupation balance in the density of states between spin majority and minority bands of the intercalated 3d elements.
Microstructuring YbRh2Si2 for resistance and noise measurements down to ultra-low temperatures
Authors: Steppke Alexander , Hamann Sandra , König Markus , Mackenzie Andrew P , Kliemt Kristin , Krellner Cornelius , Kopp Marvin , Lonsky Martin , Müller Jens , Levitin Lev V , Saunders John , Brando Manuel
Published: December 2022

The discovery of superconductivity in the quantum critical Kondo-lattice system YbRh2Si2 at an extremely low temperature of 2 mK has inspired efforts to perform high-resolution electrical resistivity measurements down to this temperature range in highly conductive materials. Here we show that control over the sample geometry by microstructuring using focused-ion-beam techniques allows to reach ultra-low temperatures and increase signal-to-noise ratios (SNRs) tenfold, without adverse effects to sample quality. In five experiments we show four-terminal sensing resistance and magnetoresistance measurements which exhibit sharp phase transitions at the Néel temperature, and Shubnikov–de-Haas (SdH) oscillations between 13 T and 18 T where we identified a new SdH frequency of 0.39 kT. The increased SNR allowed resistance fluctuation (noise) spectroscopy that would not be possible for bulk crystals, and confirmed intrinsic

1

/

f

-type fluctuations. Under controlled strain, two thin microstructured samples exhibited a large increase of

T

N

from 67 mK up to 188 mK while still showing clear signatures of the phase transition and SdH oscillations. Superconducting quantum interference device-based thermal noise spectroscopy measurements in a nuclear demagnetization refrigerator down to 0.95 mK, show a sharp superconducting transition at

T

c

=
1.2

 mK. These experiments demonstrate microstructuring as a powerful tool to investigate the resistance and the noise spectrum of highly conductive correlated metals over wide temperature ranges.
Optimal tests of genuine multipartite nonlocality
Authors: Pandit Mahasweta , Barasiński Artur , Márton István , Vértesi Tamás , Laskowski Wiesław
Published: December 2022

We propose an optimal and efficient numerical test for witnessing genuine multipartite nonlocality based on a geometric approach. In particular, we consider two non-equivalent models of local hidden variables, namely the Svetlichny and the no-signaling bilocal models. While our knowledge concerning these models is well established for Bell-type scenarios involving two measurement settings per party, the general case based on an arbitrary number of settings is a considerably more challenging task and very little work has been done in this field. In this paper, we applied such general tests to detect and characterize genuine n-way nonlocal correlations for various states of three qubits and qutrits. Apart from the fundamental problem of characterizing genuine multipartite nonlocal correlations, the extension of the number of measurements beyond two is also of practical importance. As a measure of nonlocality, we use the probability of violation of local realism under randomly sampled observables, and the strength of nonlocality, described by the resistance to white noise admixture. In particular, we analyze to what extent the Bell-type scenario involving two measurement settings can be used to certify genuine n-way nonlocal correlations generated for more general models. In addition, we propose a simple procedure to detect such nonlocal correlations for randomly chosen settings with an efficiency of up to 100%. Due to its near-perfect efficiency, our method may open new possibilities in device-independent quantum cryptography applications where strong nonlocality between all partners is required.
The effects of cavity diameter and material type of spatial confinement on intensity of laser-induced breakdown spectroscopy
Authors: Wang Yiqin , Jia Yueying , Gao Lu , Su Qi , Liu Wei , Zhou Tianchun , Xiao Qingmei
Published: December 2022

In this paper, we have investigated the spatial confinement effects on the spectrum intensity of tungsten plasma generated by laser-induced breakdown spectroscopy in the near-vacuum environment. The enhancement effects that vary with the diameters of the spatial confinement cylinders and with the material type are analyzed. We find that for an Al cylinder, the enhancement factor o reaches its highest value at diameter 4 mm. The primary causes behind this finding are attributed to the influences of diameter on the bounce time of shock wave propagating in the plasma as well as on the available range of spectrum collection. Moreover, the enhancement effect of Al cylinder is better than the other four types of materials: ZrO2, Al2O3, Fe and Cu. For each of the latter four types of materials, the thermal conductivity plays a major role on the enhancement effect, whereas for Al the enhancement effect is mainly due to its extremely large reflectivity. Particularly, for cavity with a diameter of 4 mm made of Aluminum, the maximum of the enhancement factor can approximately reach as high as 15. These experimental results indicate that the signal intensity of laser-induced breakdown spectroscopy can be dramatically improved by appropriately selecting diameter and material type of the cylindrical cavity.
Chirped soliton fission and fusion in dispersion oscillating fibers
Authors: Konyukhov A I , Mavrin P A
Published: December 2022

We found that pre-chirp of initial pulses allows to control both the fission and fusion of solitons in dispersion oscillating fiber characterized by a sinusoidally varying group velocity dispersion. The fission of second order solitons and collision of two co-propagated solitons are considered. It is shown that initial chirp can prevent the resonant fission of second order soliton into two pulses propagating with different group velocities. Inelastic collision of two in-phase solitons is found can be quite different, when the chirp imposed on initial pulses. The soliton transformation reflects in the set of output eigenvalues of the Zakharov–Shabat spectral problem. Manipulation of the input pulse chirp allows to control both real and imaginary parts of the eigenvalues at the output of the fiber.
Autonomic modulation by low-intensity focused ultrasound stimulation of the vagus nerve
Authors: Ji Ning , Li Yuanheng , Wei Jingjing , Chen Fei , Xu Lisheng , Li Guanglin , Lin Wan-Hua
Published: December 2022

Objective. Our previous study has shown that low-intensity focused ultrasound stimulation (FUS) of the vagus nerve could modulate blood pressure (BP), but its underlying mechanisms remain unclear. We hypothesized that low-intensity FUS of the vagus nerve would regulate autonomic function and thus BP. Approach. 17 anesthetized spontaneously hypertensive rats were treated with low-intensity FUS of the left vagus nerve for 15 min each trial. Continuous BP, heart rate, respiration rate (RR), and core body temperature were simultaneously recorded to evaluate the effects on BP and other physiological parameters. Heart rate variability (HRV), systolic BP variability, and baroreflex sensitivity were computed to evaluate the autonomic modulation function. A Control-sham group without stimulation and another Control-FUS group with non-target stimulation were also examined to exclude the influence of potential confounding factors on autonomic modulation. Main results. A prolonged significant decrease in BP, pulse pressure, RR, the normalized low-frequency power of HRV, and the low-to-high frequency power ratio of HRV were found after the low-intensity FUS of the left vagus nerve in comparison with the baseline and those of the control groups, demonstrating that activities of the sympathetic nervous system were inhibited. The prolonged significant increase of the normalized high-frequency power of HRV suggested the activation of parasympathetic activity. Significance. Low-intensity FUS of the left vagus nerve effectively improved the autonomic function by activating parasympathetic efferent and inhibiting sympathetic efferent, which contributes to BP reduction. The findings shed light on the hypotensive mechanism underlying FUS.
Dislocation structure of tungsten irradiated by light ions
Authors: Wieluńska-Kuś B. , Płociński T. , Schwarz-Selinger T. , Mayer M. , Jacob W. , Ciupiński L.
Published: December 2022

Single crystalline tungsten samples were irradiated by He, D, and H at room temperature, with a calculated damage level in the peak maximum up to 0.04 dpa and with He up to 0.5 dpa. The dislocation structure of the whole damage zone was investigated perpendicular to the irradiated surface by Transmission Electron Microscopy (TEM) under four different two-beam diffraction conditions
g =−200, 020, −110, 110 close to the [100] zone axis, taking bright-field kinematical images. The depth of the damage zone observed by TEM is in good agreement with the damage depth calculated by SRIM. The damage zones of the tungsten samples irradiated by He, D, H up to 0.04 dpa can be subdivided into four subzones. Significant differences in the dislocation structures between the different ion species despite comparable calculated damage levels were found at the depth close to the damage peak maximum. In this depth, the damage zone of tungsten irradiated by He consists of small dense dislocation loops (⩽3 nm) with high strain fields. Irradiation by D creates large dislocation loops with an average diameter of 15–22 nm depending on the set diffraction condition. The damage zone of H-irradiated tungsten is dominated by long dislocation lines at the depth of the damage peak maximum. No transition from dislocation loops to lines was found in the sample irradiated with He up to 0.5 dpa. This is probably due to He bubbles, which hinder the loops to aggregate into lines. This work shows that the displacement damage obtained by the irradiation of tungsten at room temperature with light ions is significantly different to tungsten irradiated to the same calculated damage level by medium to high-mass ions (Wielunska et al 2022 Nucl. Fusion
62 096003 [1]).
3D pulmonary fibrosis model for anti-fibrotic drug discovery by inkjet-bioprinting
Authors: Kang Dayoon , Lee Yunji , Kim Wookyeom , Lee Hwa-Rim , Jung Sungjune
Published: December 2022

Pulmonary fibrosis (PF) is known as a chronic and irreversible disease characterized by excessive extracellular matrix accumulation and lung architecture changes. Large efforts have been made to develop prospective treatments and study the etiology of pulmonary fibrotic diseases utilizing animal models and spherical organoids. As part of these efforts, we created an all-inkjet-printed three-dimensional (3D) alveolar barrier model that can be used for anti-fibrotic drug discovery. Then, we developed a PF model by treating the 3D alveolar barrier with pro-fibrotic cytokine and confirmed that it is suitable for the fibrosis model by observing changes in structural deposition, pulmonary function, epithelial–mesenchymal transition, and fibrosis markers. The model was tested with two approved anti-fibrotic drugs, and we could observe that the symptoms in the disease model were alleviated. Consequently, structural abnormalities and changes in mRNA expression were found in the induced fibrosis model, which were shown to be recovered in all drug treatment groups. The all-inkjet-printed alveolar barrier model was reproducible for disease onset and therapeutic effects in the human body. This finding emphasized that the in vitro artificial tissue with faithfully implemented 3D microstructures using bioprinting technology may be employed as a novel testing platform and disease model to evaluate potential drug efficacy.
Prominent vegetation greening in spring and autumn across China during the 1981–2018 period
Authors: Li Mingxing , Wu Peili , Ma Zhuguo , Liu Jiandong
Published: December 2022

Vegetation greening in China has been extensively examined, but little is known about its seasonal characteristics and its association with soil moisture (SM) and temperature changes. Using high-resolution (0.1°, 8 d) datasets of leaf area index (LAI), together with SM, soil temperature (ST) datasets, and the dominance analysis method, this study is designed to detect seasonal vegetation changes across China during 1981–2018 and its links to climate change. The results show that 56.8% of land area across China experienced a greening trend while 6.6% browning trend through 1981–2018. LAI increasing area expanded to a maximum of 59.3% in spring and the decreasing area reached a maximum of 10.6% in autumn. Spring increases in LAI in main vegetation regions were significantly correlated with positive ST anomalies, while autumn decreases in LAI except sparsely vegetated regions were correlated with negative SM anomalies. Combined SM and temperature anomalies explain 10.9% of the observed LAI changes, which is 4 times larger than that directly explained by precipitation and surface air temperature (2.7%). The warming of soil under climate change was driving the LAI increases, while drying was largely responsible for LAI decreases. These findings provide further evidence of climate change impacts on regional ecosystems and highlight the importance of soil heat and water conditions in translating global warming signals.
The impact of dementia, frailty and care home characteristics on SARS-CoV-2 incidence in a national cohort of Welsh care home residents during a period of high community prevalence
Authors: Emmerson Chris , Hollinghurst Joseph , North Laura , Fry Richard , Akbari Ashley , Humphreys Ciarán , Gravenor Mike B , Lyons Ronan A
Published: December 2022

Background

dementia may increase care home residents’ risk of COVID-19, but there is a lack of evidence on this effect and on interactions with individual and care home-level factors.

Methods

we created a national cross-sectional retrospective cohort of care home residents in Wales for 1 September to 31 December 2020. Risk factors were analysed using multi-level logistic regression to model the likelihood of SARS-CoV-2 infection and mortality.

Results

the cohort included 9,571 individuals in 673 homes. Dementia was diagnosed in 5,647 individuals (59%); 1,488 (15.5%) individuals tested positive for SARS-CoV-2. We estimated the effects of age, dementia, frailty, care home size, proportion of residents with dementia, nursing and dementia services, communal space and region. The final model included the proportion of residents with dementia (OR for positive test 4.54 (95% CIs 1.55–13.27) where 75% of residents had dementia compared to no residents with dementia) and frailty (OR 1.29 (95% CIs 1.05–1.59) for severe frailty compared with no frailty). Analysis suggested 76% of the variation was due to setting rather than individual factors. Additional analysis suggested severe frailty and proportion of residents with dementia was associated with all-cause mortality, as was dementia diagnosis. Mortality analyses were challenging to interpret.

Discussion

whilst individual frailty increased the risk of COVID-19 infection, dementia was a risk factor at care home but not individual level. These findings suggest whole-setting interventions, particularly in homes with high proportions of residents with dementia and including those with low/no individual risk factors may reduce the impact of COVID-19.
A realist evaluation of a multifactorial falls prevention programme in care homes
Authors: Leighton Paul A , Darby Janet , Allen Frances , Cook Marie , Evley Rachel , Fox Chris , Godfrey Maureen , Gordon Adam , Gladman John , Horne Jane , Robertson Kate , Logan Pip
Published: December 2022

Background

falls in care homes are common, costly and hard to prevent.

Multifactorial falls programmes demonstrate clinical and cost-effectiveness, but the heterogeneity of the care home sector is a barrier to their implementation. A fuller appreciation of the relationship between care home context and falls programme delivery will guide development and support implementation.

Methods

this is a multi-method process evaluation informed by a realist approach.

Data include fidelity observations, stakeholder interviews, focus groups, documentary review and falls-rate data. Thematic analysis of qualitative data and descriptive statistics are synthesised to generate care home case studies.

Results

data were collected in six care homes where a falls programme was trialled. Forty-four interviews and 11 focus groups complemented observations and document review.

The impact of the programme varied. Five factors were identified: (i) prior practice and (ii) training may inhibit new ways of working; (iii) some staff may be reluctant to take responsibility for falls; (iv) some may feel that residents living with dementia cannot be prevented from falling; and, (v) changes to management may disturb local innovation.

In some care homes, training and improved awareness generated a reduction in falls without formal assessments being carried out.

Conclusions

different aspects of the falls programme sparked different mechanisms in different settings, with differing impact upon falls.

The evaluation has shown that elements of a multifactorial falls programme can work independently of each other and that it is the local context (and local challenges faced), which should shape how a falls programme is implemented.
Genomics and multimorbidity
Authors: Masoli Jane A H , Pilling Luke C , Frayling Timothy M
Published: December 2022

Multimorbidity has increased in prevalence world-wide. It is anticipated to affect over 1 in 6 of the UK population by 2035 and is now recognised as a global priority for health research. Genomic medicine has rapidly advanced over the last 20 years from the first sequencing of the human genome to integration into clinical care for rarer conditions. Genetic studies help identify new disease mechanisms as they are less susceptible to the bias and confounding that affects epidemiological studies, as genetics are assigned from conception. There is also genetic variation in the efficacy of medications and the risk of side effects, pharmacogenetics. Genomic approaches offer the potential to improve our understanding of mechanisms underpinning multiple long-term conditions/multimorbidity and guide precision approaches to risk, diagnosis and optimisation of management. In this commentary as part of the Age and Ageing 50th anniversary commentary series, we summarise genomics and the potential utility of genomics in multimorbidity.