bluuebunny/crossref_metadata_2025 huggingface dataset:
Generation of a bright four-photon entangled state from a warm atomic ensemble via inherent polarization entanglement
Authors: Park Jiho , Moon Han Seb
Published: January 2022

We report the stable generation of a bright four-photon polarization-entangled Greenberger–Horne–Zeilinger (GHZ) state obtained by the spatial multiplexing of inherently polarization-entangled photons from a warm atomic ensemble of 87Rb. Owing to the total angular momentum conservation of the atomic state in the spontaneous four-wave mixing process of a cascade-type atomic system, the polarizations of the signal and idler photons in the two-photon decay are entangled. With a Rb vapor cell, we realize the generation of robust and bright four-photon GHZ states using two symmetrical spatial modes of inherently polarization-entangled photon pairs without applying an interferometric configuration. The four-photon average coincidence rate of the GHZ state with a fidelity of 0.88(2) is measured as 1.69(7) Hz under a weak pump power of 10 μW. The minimum Allan variance for the stability of the four-photon GHZ state is estimated as 0.92° for an average time of 10 h.
Ultra-high energy storage density of transparent capacitors based on linear dielectric ZrO2 thin films with the thickness scaled up to hundreds nanometers
Authors: Wang Yanbin , Wang Yong , Zeng Huizhong , Wei Xianhua
Published: January 2022

In this work, a high energy storage density in transparent capacitors, based on linear dielectric ZrO2 thin films, with thickness scaled up to hundreds of nanometers, is reported. Linear dielectric ZrO2 films with a thickness of several hundred nanometers are grown on Sn-doped In2O3 (ITO) electrode layers grown on transparent glass substrates at room temperature. The fabricated ITO/ZrO2/ITO capacitors show excellent dielectric energy storage performance, including a large dielectric constant, low loss and leakage current, and large breakdown strength. Consequently, these capacitors present high energy density and efficiency, as well as robust device endurance. In particular, ultra-high recoverable energy storage density (Wrec ∼ 75.4 J/cm3) and efficiency (η ∼ 88%) are achieved simultaneously in ZrO2 film-based (470 nm thick) capacitors, rivaling those of other lead-free ferroelectric-like and other linear dielectric film capacitors. Moreover, the capacitors show good transparency in the visible range, indicating the potential energy-storage applications in transparent electronics.
Stabilization of layered perovskite structures via strontium substitution in Ca3Ti2O7 revealed via elemental mapping
Authors: Kurushima Kosuke , Nakajima Hiroshi , Mine Shinya , Tsukasaki Hirofumi , Matsuoka Masaya , Gao Bin , Cheong Sang-Wook , Mori Shigeo
Published: January 2022

Extensive studies have been performed on layered compounds, ranging from layered cuprates to van der Waals materials with critical issues of intergrowths and stacking faults. However, such structures have been studied less because of experimental difficulty. We present characteristic defect structures of intergrowths in the Ruddlesden–Popper Ca2.46Sr0.54Ti2O7, which is known to exhibit hybrid improper ferroelectricity. Transmission electron microscopy reveals that numerous intergrowths composed of 7 and 15 layers are introduced in the ferroelectric domains. Elemental maps demonstrate that Sr ions are selectively substituted into the perovskite layers of intergrowths. Density functional theory calculations support the site-selective substitution of Sr ions, favorably located in the intergrowths. The stabilization of the Ruddlesden–Popper phase and intergrowths via Sr substitution can be explained by the ionic-radius difference between Ca and Sr ions. The study reveals detailed defect structures originating from the layered perovskite structure of Ca2.46Sr0.54Ti2O7 and shows the usefulness of elemental mapping in probing the substitution effects in oxides.
Unbalanced clustering and solitary states in coupled excitable systems
Authors: Franović Igor , Eydam Sebastian , Semenova Nadezhda , Zakharova Anna
Published: January 2022

We discover the mechanisms of emergence and the link between two types of symmetry-broken states, the unbalanced periodic two-cluster states and solitary states, in coupled excitable systems with attractive and repulsive interactions. The prevalent solitary states in non-locally coupled arrays, whose self-organization is based on successive (order preserving) spiking of units, derive their dynamical features from the corresponding unbalanced cluster states in globally coupled networks. Apart from the states with successive spiking, we also find cluster and solitary states where the interplay of excitability and local multiscale dynamics gives rise to so-called leap-frog activity patterns with an alternating order of spiking between the units. We show that the noise affects the system dynamics by suppressing the multistability of cluster states and by inducing pattern homogenization, transforming solitary states into patterns of patched synchrony.
Self-trapped holes and polaronic acceptors in ultrawide-bandgap oxides
Authors: Lyons John L.
Published: January 2022

Although Ga2O3 is widely believed to be one of the most promising ultrawide-bandgap semiconductors, its inability to be p-type doped hampers its future applications. Other oxides have recently emerged as potential competitors to Ga2O3, but their propensity for hole conductivity is less well known. Here, the stability of hole polarons is examined in pristine material and in the presence of impurities for a set of ultrawide-bandgap oxides (Ga2O3, Al2O3, ZnGa2O4, MgGa2O4, LiGaO2, and GeO2). Holes spontaneously self trap in all oxides investigated here. Acceptor impurities (such as group-I elements, N, and F) further stabilize these trapped holes, leading to large acceptor ionization energies. Hole trapping also leads to characteristic distortions and distinct optical transitions, which may explain some experimentally observed signals. These results indicate that achieving p-type conductivity in any of these oxides is unlikely, with the possible exception of GeO2.
The design of heterojunctions based on boron-/phosphorus-doped graphene and ZnO monolayer to enhance adsorption properties for toxic gases
Authors: Ding Jijun , Jin Yanxin , Chen Haixia , Fu Haiwei , Xu Chao , Xiao Bing
Published: January 2022

Boron-/phosphorus-doped graphene and ZnO monolayer (B-G/ZnO and P-G/ZnO) heterojunctions are modeled. The density functional theory is performed to investigate the optimal adsorption configurations, electronic and adsorption properties of oxycarbide (CO, CO2), oxynitride (NO, NO2), and sulfide (SO2, H2S) gas molecules adsorbed on the heterojunctions. Results indicate that the adsorption characteristics of both B-G/ZnO and P-G/ZnO heterojunctions are better than those of G/ZnO heterojunction. Specifically, NO2 and SO2 gas molecules are chemisorbed on doped heterojunctions, and the adsorption energies are almost three times more than that on the G/ZnO heterojunction. Then, the two gas molecules are simultaneously adsorbed on the two opposite terminals of the doped G/ZnO heterojunctions to evaluate the influence of gas concentration on electronic and adsorption properties of the G/ZnO heterojunction. It is found that the adsorption energy almost doubles compared with adsorbing a gas molecule, which provides a new idea to regulate the electronic and adsorption properties of the G/ZnO heterojunction. In addition, the bandgap of graphene can be opened by B and P atom doping and the p–n junction and n–n junction can be formed with the ZnO monolayer, respectively. The theoretical investigation helps us to better understand the mechanism of G/ZnO heterojunctions as gas sensors and offers the guidance for future p–n and n–n junction designs used in advanced gas sensor devices.
Investigation of effective parameters on streaming-induced acoustophoretic particle manipulation in a microchannel via three-dimensional numerical simulation
Authors: Marefati Sanaz , Ghassemi Majid , Ghazizadeh Vahid
Published: January 2022

Particle manipulation using ultrasonic standing waves has gained increased attention in recent years as it is efficient and noninvasive. In order to predict the effects of acoustic streaming on the concentration of particles in the actual microchannel geometry, this paper presents a 3D numerical study on the transient motion of microparticles suspended in a liquid-filled microchannel, considering the mixed standing and traveling waves. The motion was generated by the acoustic radiation force and acoustic streaming-induced drag force arising from an imposed bulk acoustic wave and the hydrodynamic drag. The acoustic streaming patterns in the 3D microchannel were investigated using the limiting velocity method. In addition, the effects of the 3D streaming pattern in an acoustofluidic device on the acoustophoretic motion of microparticles were evaluated. The concentration of polystyrene particles was simulated for many particles with diameters of 0.5, 2, and 5 μm released from random initial locations. The obtained results indicate a balance between the flow rate and the particle diameter to achieve the highest concentration percentage. Increasing the height increased the concentration of large 5-μm-diameter particles to more than 80%. By doubling the length of the piezoelectrically actuated region, the concentration of 2-μm particles improved by approximately 20%. Finally, increasing the viscosity of the fluid by using a 50% glycerol-in-water mixture resulted in a greater effect of acoustic streaming. This study can provide helpful guidance for optimizing the design of acoustofluidic devices to enhance experiments.
Spatters and spills: Spreading dynamics for partially wetting droplets
Authors: Durian Sylvia C. L. , Dillavou Sam , Markin Kwame , Portales Adrian , Maldonado Bryan O. Torres , Irvine William T. M. , Arratia Paulo E. , Durian Douglas J.
Published: January 2022

We present a solvable model inspired by dimensional analysis for the time-dependent spreading of droplets that partially wet a substrate, where the spreading eventually stops and the contact angle reaches a nonzero equilibrium value. We separately consider small droplets driven by capillarity and large droplets driven by gravity. To explore both regimes, we first measure the equilibrium radius vs a comprehensive range of droplet volumes for four household fluids, and we compare the results with predictions based on minimizing the sum of gravitational and interfacial energies. The agreement is good and gives a reliable measurement of an equilibrium contact angle that is consistent in both small and large droplet regimes. Next, we use energy considerations to develop equations of motion for the time dependence of the spreading, in both regimes, where the driving forces are balanced against viscous drag in the bulk of the droplet and by friction at the moving contact line. Our approach leads to explicit prediction of the functional form of the spreading dynamics. It successfully describes prior data for a small capillary-driven droplet, and it fits well to new data we obtain for large gravity-driven droplets with a wide range of volumes. While our prediction for the dynamics of small capillary-driven droplets assumes the case of thin nearly wetting droplets, with a small contact angle, this restriction is not otherwise invoked.
Probing chirality across the electromagnetic spectrum with the full semi-classical light–matter interaction
Authors: van Horn Martin , Saue Trond , List Nanna Holmgaard
Published: January 2022

We present a formulation and implementation of anisotropic and isotropic electronic circular dichroism (ECD) using the full semi-classical light–matter interaction operator within a four-component relativistic framework. Our treatment uniquely accounts for both beyond-first-order light–matter interactions and relativistic effects, enabling us to investigate the ECD response across the electromagnetic spectrum from optical to x-ray wavelengths where relativistic selection rules and spatial field variations gain increasing importance. We consider the isotropic and oriented ECD across the valence transition and sulfur L- and K-edge transitions in the simplest disulfides, H2S2 and (CH3S)2, and evaluate the influence of the full interaction by comparing to a traditional truncated formulation in the Coulomb gauge (velocity representation). Additionally, we demonstrate that in the relativistic formalism, it is possible to work in the velocity representation, hence keeping order-by-order gauge-origin invariance, contrary to the multipolar gauge, yet being able to distinguish electric and magnetic multipole contributions. Going beyond a first-order treatment in the wave vector is mandatory in the higher-energy end of the soft x-ray region and beyond where the consequent intensity redistribution becomes significant. While the sulfur K-edge absorption spectrum is essentially unaffected by this redistribution, the signed differential counterpart is not: At least third-order contributions are required to describe the differential absorption profile that is otherwise overestimated by a factor of about two. The first-order description deteriorates at higher transition energies (beyond ∼1000 eV) where it may even fail to predict the sign of individual differential oscillator strengths.
Anisotropic frontal polymerization in a model resin–copper composite
Authors: Gao Yuan , Li Sarah , Kim Jin-Young , Hoffman Imogen , Vyas Sagar K. , Pojman John A. , Geubelle Philippe H.
Published: January 2022

This work investigates experimentally and numerically frontal polymerization in a thermally anisotropic system with parallel copper strips embedded in 1,6-hexanediol diacrylate resin. Both experiments and multiphysics finite element analyses reveal that the front propagation in the thermally anisotropic system is orientation-dependent, leading to variations in the front shape and the front velocity due to the different front–metal strip interaction mechanisms along and across the metal strips. The parameters entering the cure kinetics model used in this work are chosen to capture the key characteristics of the polymerization front, i.e., the front temperature and velocity. Numerical parametric analyses demonstrate that the front velocity in the directions parallel and perpendicular to the metal strips increases as the system size decreases and approaches the analytical prediction for homogenized systems. A two-dimensional homogenized model for anisotropic frontal polymerization in the metal–resin system is proposed.
Learn bifurcations of nonlinear parametric systems via equation-driven neural networks
Authors: Hao Wenrui , Zheng Chunyue
Published: January 2022

Nonlinear parametric systems have been widely used in modeling nonlinear dynamics in science and engineering. Bifurcation analysis of these nonlinear systems on the parameter space is usually used to study the solution structure, such as the number of solutions and the stability. In this paper, we develop a new machine learning approach to compute the bifurcations via so-called equation-driven neural networks (EDNNs). The EDNNs consist of a two-step optimization: the first step is to approximate the solution function of the parameter by training empirical solution data; the second step is to compute bifurcations using the approximated neural network obtained in the first step. Both theoretical convergence analysis and numerical implementation on several examples have been performed to demonstrate the feasibility of the proposed method.
Characterization of hydrogen bond network of waters around polyethylene glycol by broadband dielectric spectroscopy
Authors: Hu Junru , Yamahara Hiroyasu , Liao Zhiqiang , Yano Yasuo , Tabata Hitoshi
Published: January 2022

Polyethylene glycol (PEG) is a well-known water retention agent in biomedical products, the hydration efficiency of which is affected by its molecular weight. Using a broadband dielectric spectroscopy (100 MHz–18 THz), the hydration state of PEG aqueous solutions with various molecular weights was quantitatively evaluated. As the molecular weight increases, the restriction strength of hydration water increases in potency, while the number of hydration water molecules decreases. Owing to the opposite changes in hydration number and restriction strength, the measured collective hydrogen bond (HB) strength shows negligible molecular weight dependence. PEG with larger Mw produces a more heterogenous HB network. The internal folding and twining caused by the growth of the PEG chain obstruct the proper exposure of hydrophilic part of the monomer producing less hydration waters. The evaluation result supports an application of PEGs with low molecular weight in contact lens package solutions.
Bimolecular reactions on sticky and slippery clusters: Electron-induced
reactions of hydrogen peroxide
Authors: Poštulka Jan , Slavíček Petr , Pysanenko Andriy , Poterya Viktoriya , Fárník Michal
Published: January 2022

Nanoparticles can serve as an efficient reaction environment for bimolecular reactions as the reactants concentrate either inside the nanoparticle or on the surface of the nanoparticle. The reaction rate is then controlled by the rate of formation of the reaction pairs. We demonstrate this concept on the example of electron-induced reactions in hydrogen peroxide. We consider two types of nanoparticle environments: solid argon particles, only weakly interacting with the hydrogen peroxide reactant, and ice particles with a much stronger interaction. The formation of hydrogen peroxide dimers is investigated via classical molecular dynamics (MD) simulations on a microsecond timescale. With a modified force field for hydrogen peroxide, we found out a fast formation and stabilization of the hydrogen peroxide dimer for argon nanoparticles, while the reaction pair was formed reversibly at a much slower rate on the water nanoparticles. We have further investigated the electron-induced reactions using non-adiabatic ab initio MD simulations, identifying the possible reaction products upon the ionization or electron attachment. The major reaction path in all cases corresponded to a proton transfer. The computational findings are supported by mass spectrometry experiments, where large ArM and (H2O)M nanoparticles are generated, and several hydrogen peroxide molecules are embedded on these nanoparticles in a pickup process. Subsequently, the nanoparticles are ionized either positively by 70 eV electrons or negatively by electron attachment at electron energies below 5 eV. The recorded mass spectra demonstrate the efficient coagulation of H2O2 on ArM, while it is quite limited on (H2O)M.
Analysis of the classical trajectory treatment of photon dynamics for polaritonic phenomena
Authors: Rosenzweig Bart , Hoffmann Norah M. , Lacombe Lionel , Maitra Neepa T.
Published: January 2022

Simulating photon dynamics in strong light–matter coupling situations via classical trajectories is proving to be powerful and practical. Here, we analyze the performance of the approach through the lens of the exact factorization approach. Since the exact factorization enables a rigorous definition of the potentials driving the photonic motion, it allows us to identify that the underestimation of photon number and intensities observed in earlier work is primarily due to an inadequate accounting of light–matter correlation in the classical Ehrenfest force rather than errors from treating the photons quasiclassically per se. The latter becomes problematic when the number of photons per mode begins to exceed a half.
Thermal transport and mixed valence in ZrTe3 doped with Hf and Se
Authors: Liu Yu , Hu Zhixiang , Tong Xiao , Leshchev Denis , Zhu Xiangde , Lei Hechang , Stavitski Eli , Attenkofer Klaus , Petrovic C.
Published: January 2022

Two-dimensional transition metal trichalcogenides (TMTCs) feature covalently bonded metal-chalcogen layers separated by the van der Waals (vdW) gap. Similar to transition metal dichalcogenides (TMDCs), TMTCs often host charge density waves (CDWs) and superconductivity, but unlike TMDCs, atomic chains in the crystal structure give rise to quasi one-dimensional (quasi 1D) conduction. ZrTe3 features the CDW below TCDW = 63 K and filamentary superconductivity below 2 K that can be enhanced by pressure or chemical substitution. Here, we report the presence of mixed valent Zr2+ and Zr4+ atoms in ZrTe3 crystals that are reduced by doping in ZrTe3−xSex and Zr1−yHfyTe3. Superconductivity is enhanced via disorder in Te2-Te3 atomic chains that are associated with CDW formation. Hf substitution on the Zr atomic site enhances TCDW due to unperturbed Te2-Te3 chain periodicity and enhanced electron-phonon coupling. Weak electronic correlations in ZrTe3−xSex are likely governed by the lattice contraction effects.
A thermoacoustic heat pump driven by acoustic waves in a hypersonic boundary layer
Authors: Yu Jiaming , Zhu Yiding , Gu Dingwei , Lee Cunbiao
Published: January 2022

Acoustic waves existing in hypersonic boundary layers act as a heat pump that transfers energy from the sonic line to the wall causing the wall temperature to rise, which explains the newly identified aerodynamic heating related to Mack's second mode from the perspective of thermoacoustic effects. The analysis of data from direct numerical simulations shows that Mack's second mode, belonging to the family of trapped acoustic waves, is highly amplified in a Mach 6 boundary layer and becomes sufficiently strong to affect the mean wall-normal temperature gradient, and the energy transport in the wall-normal direction due to the thermoacoustic effect balancing the thermal conduction brought by the additional temperature gradient.
How to quantify and avoid finite size effects in computational studies of crystal nucleation: The case of homogeneous crystal nucleation
Authors: Hussain Sarwar , Haji-Akbari Amir
Published: January 2022

Finite size artifacts arise in molecular simulations of nucleation when critical nuclei are too close to their periodic images. A rigorous determination of what constitutes too close is, however, a major challenge. Recently, we devised rigorous heuristics for detecting such artifacts based on our investigation of how system size impacts the rate of heterogeneous ice nucleation [S. Hussain and A. Haji-Akbari, J. Chem. Phys. 154, 014108 (2021)]. We identified the prevalence of critical nuclei spanning across the periodic boundary, and the thermodynamic and structural properties of the liquid occupying the inter-image region as indicators of finite size artifacts. Here, we further probe the performance of such heuristics by examining the dependence of homogeneous crystal nucleation rates in the Lennard-Jones (LJ) liquid on system size. The rates depend non-monotonically on system size and vary by almost six orders of magnitude for the range of system sizes considered here. We confirm that the prevalence of spanning critical nuclei is the primary indicator of finite size artifacts and almost fully explains the observed variations in rate. Proximity, or structuring of the inter-image liquid, however, is not as strong of an indicator due to the fragmented nature of crystalline nuclei. As a result, the dependence of rate on system size is subtle for the systems with a minuscule fraction of spanning critical nuclei. These observations indicate that our heuristics are universally applicable to different modes of nucleation (homogeneous and heterogeneous) in different systems even if they might be overly stringent for homogeneous nucleation, e.g., in the LJ system.
Thermodynamic or density scaling of the electrical conductivity of molten salts
Authors: Harris Kenneth R.
Published: January 2022

Thermodynamic or density scaling of high-pressure conductivities and molar conductivities of the high-temperature molten salts NaOH, and the alkali chlorides, bromides, and nitrates, from Na to Cs, taken from the literature, is found to be consistent with the simulations of Knudsen, Niss, and Bailey (KNB). They used a simple model fluid of point particles interacting through an interionic potential with a repulsive inverse power law part varying as r−9 and an attractive Coulombic part. This yields values between the limits 0.33–3 for the scaling parameter, γ. The Coulombic potential reduces the scaling parameter to values much lower than are normally found for molecular liquids, and KNB used this to explain the low values typically found for ionic liquids. Here, it is shown that the high-temperature molten salts examined behave similarly.
Bifunctions of invisible sensors and cloaks in thermal–electric fields
Authors: Feng Huolei , Ni Yushan
Published: January 2022

The thermal–electric bifunctional devices with isotropic and anisotropic geometries are designed in this paper, which can realize different control functions (invisible sensors and cloaks) of thermal and electric fields. We first theoretically achieve the bifunctions of invisible sensors and cloaks with isotropic and anisotropic geometries. When the material parameters of the core and matrix and the geometric parameters of the core, inner shell, and outer shell are determined, the thermal–electric invisible sensors could be realized. Meanwhile, the invisible sensors will degrade to invisible cloaks as the inner shell material is insulating. The simulations applying the derived material parameters have also been conducted to verify the thermal–electric bifunctions of different circular and confocal elliptical devices. The results show that the thermal–electric bifunctional devices can effectively control the thermal and electric fields, and these devices exhibit perfect performance of the thermal–electric functions of invisible sensors and cloaks. This work presents a new method to realize thermal–electric bifunctional devices and opens a new window to the development of multi-physics field.
Electrolyte-gated transistors with good retention for neuromorphic computing
Authors: Li Yue , Xu Han , Lu Jikai , Wu Zuheng , Wu Shuyu , Zhang Xumeng , Liu Qi , Shang Dashan
Published: January 2022

Electrolyte-gated transistors (EGTs) provide prominent analog switching performance for neuromorphic computing. However, suffering from self-discharging nature, the retention performance greatly hampers their practical applications. In this Letter, we realize a significant improvement in EGT retention by inserting a SiO2 layer between the gate electrode and electrolyte. The dynamic process behind the improvement is interpreted by an assumptive leakage-assisted electrochemical mechanism. In addition to improved retention, analog switching with a large dynamic range, superior linearity and symmetry, and low variation has been achieved using identical voltage pulses. Based on the experimental data, a nearly ideal recognition accuracy of 98% has been demonstrated by simulations using the handwritten digit data sets. The obtained results pave a way for employing EGT in future neuromorphic computing.
Charge-transfer complexes of arylthiotetrathiafulvalenes and TCNQF4: their structural diversity and electronic states
Authors: Ma Longfei , Pan Congjie
Published: January 2022

A series of charge-transfer (CT) complexes have been prepared via diffusion and evaporation methods comprising arylthio-substituted tetrathiafulvalene (Ar-S-TTF) derivatives 1–5 and TCNQF4. Crystallographic studies revealed the diverse crystal packing of the CT complexes, which is related to their flexible structure and the planar central cores of the Ar-S-TTF. The complexes could be divided into three systems according to the packing similarities and dissimilarities of Ar-S-TTF (donor, D) and TCNQF4 (acceptor, A), namely Class 1 (D on D and A on A segregated stacking), Class 2 ((–A–D–)n mixed stacking) and Class 3 (–D–D–D–D– and A, A stacks with each other in edge-to-face interactions between cations and anions). The presence of multiple intermolecular interactions promotes the formation of various stacking structures. There are two factors affecting the packing structures and compositions of the CT complexes: (1) the aryl groups thereon of Ar-S-TTF; and (2) the expanded π-conjugated system.
Mary Proctor and the Cawthron observatory project: a lost history of the Mount Stromlo Observatory
Authors: Bush Martin
Published: January 2022

Between 1912 and 1914, the Anglo-American popularizer of astronomy, Mary Proctor, undertook a tour of Australia and New Zealand in order to promote a solar observatory project that would ultimately be realized as the Mount Stromlo Observatory in Australia. Proctor came at the request of Walter Geoffrey Duffield, who would go on to be the first Director of the Mt Stromlo Observatory and who saw the need to raise funds and public support for the project. Proctor’s tour was high-profile and nearly saw the realization of a solar observatory as part of the Cawthron Institute at Nelson, New Zealand. Despite this, Proctor’s tour is absent from histories of Mount Stromlo and, until recently, had also been overlooked in New Zealand. I argue that this historical lacuna speaks to a number of historiographical biases: for success over failure; against the role of public activities in scientific work; and downplaying the contribution of women. Mary Proctor was a significant transitional figure in the history of early twentieth-century science-communication who should be more widely recognised.
Microestimates of wealth for all low- and middle-income countries
Authors: Chi Guanghua , Fang Han , Chatterjee Sourav , Blumenstock Joshua E.
Published: January 2022

Significance

Many critical policy decisions rely on data about the geographic distribution of wealth and poverty, yet only half of all countries have access to adequate data on poverty. This paper creates a complete and publicly available set of microestimates of the distribution of relative poverty and wealth across all 135 low- and middle-income countries. We provide extensive evidence of the accuracy and validity of the estimates and also provide confidence intervals for each microestimate to facilitate responsible downstream use. These methods and maps provide a set of tools to study economic development and growth, guide interventions, monitor and evaluate policies, and track the elimination of poverty worldwide.
Open reading frame correction using splice-switching antisense oligonucleotides for the treatment of cystic fibrosis
Authors: Michaels Wren E. , Pena-Rasgado Cecilia , Kotaria Rusudan , Bridges Robert J. , Hastings Michelle L.
Published: January 2022

Significance

Frameshift and nonsense mutations pose a major problem for disease therapeutic development. Eliminating these mutations from the messenger RNA by inducing exon skipping is a relatively unexplored treatment approach, though it has shown promise for some diseases. Here, we show that eliminating a common stop mutation associated with cystic fibrosis (CF), by inducing the skipping of the exon it is located in, results in a restoration of the open reading frame and recovers CFTR protein function in a manner expected to be therapeutic in CF patients who don’t currently have effective treatment options. These results are an important advancement for the CF community but also have implications for other diseases where terminating mutations are responsible for dysfunction.
MICROSCOPE: systematic errors
Authors: Rodrigues Manuel , Touboul Pierre , Métris Gilles , Robert Alain , Dhuicque Océane , Bergé Joel , André Yves , Boulanger Damien , Chhun Ratana , Christophe Bruno , Cipolla Valerio , Danto Pascale , Foulon Bernard , Guidotti Pierre-Yves , Hardy Emilie , Huynh Phuong-Anh , Lebat Vincent , Liorzou Françoise , Pouilloux Benjamin , Prieur Pascal , Reynaud Serge , Torresi Patrizia
Published: January 2022

The MICROSCOPE mission aims to test the weak equivalence principle (WEP) in orbit with an unprecedented precision of 10−15 on the Eötvös parameter thanks to electrostatic accelerometers on board a drag-free micro-satellite. The precision of the test is determined by statistical errors, due to the environment and instrument noises, and by systematic errors to which this paper is devoted. Systematic error sources can be divided into three categories: external perturbations, such as the residual atmospheric drag or the gravity gradient at the satellite altitude, perturbations linked to the satellite design, such as thermal or magnetic perturbations, and perturbations from the instrument internal sources. Each systematic error is evaluated or bounded in order to set a reliable upper bound on the WEP parameter estimation uncertainty.
A novel piezoelectric RF-MEMS resonator with enhanced quality factor
Authors: Li Jinchao , Chen Zeji , Liu Wenli , Yang Jinling , Zhu Yinfang , Yang Fuhua
Published: January 2022

This work presents a novel ultra-high frequency Lamb mode Aluminum nitride piezoelectric resonator with enhanced quality factors (Q). With slots introduced in the vicinity of the tether support end, the elastic waves leaking from the tether sidewalls can be reflected, which effectively reduces the anchor loss while retaining size compactness and mechanical robustness. Comprehensive analysis was carried out to provide helpful guidance for obtaining optimal slot designs. For various resonators with frequencies ranging from 630 MHz to 1.97 GHz, promising Q enhancements up to 2 times have all been achieved. The 1.97 GHz resonator implemented excellent f × Q product up to 6.72 × 1012 and low motional resistance down to 340 Ω, which is one of the highest performances among the reported devices. The devices with enhanced Q values as well as compact size possess potential application in advanced radio frequency front end transceivers.
Compact transition enabled broadband propagation of spoof surface plasmon polaritons based on the equivalent circuit model
Authors: Zhang Dawei , Liu Xin , Sun Yaxiu , Zhang Kuang , Wu Qun , Li Yingsong , Jiang Tao
Published: January 2022

In this paper, a strategy to develop a compact transition of the spoof surface plasmon polariton (SSPP) transmission line (TL) is proposed. First, an equivalent distributed circuit model is employed for the theoretical analysis and optimization design of the SSPP unit. The mapping relation between the unit performance and the geometric parameters is deduced from the transmission matrix. The calculated results are compared with the numerical ones from the three-dimensional (3D) simulations for validation. Then, a compact transition (only 0.26λ
g) is built with only two matching units and a tapered strip through optimizations. The optimizations are implemented with the circuit simulations based on the equivalent model, which can remarkably save time in comparison with the 3D simulations. The transition principle is also explained by quantitatively extracting the dispersion properties and impedance characteristics. Finally, a prototype of the proposed SSPP TL is fabricated and measured for demonstration. The measured operating band (0–7.7 GHz) is almost up to the cut-off frequency (about 8 GHz), which remains the inherent broadband low-pass transmission characteristics. Meanwhile, the measured in-band return loss is almost higher than 10 dB, which verifies the high-efficiency propagation. This work can pave the way for building up a new SSPP-based framework of microwave circuits.
Large magnetodielectric coupling in the vicinity of metamagnetic transition in 6H–perovskite Ba3GdRu2O9
Authors: Chhillar S , Mukherjee K , Yadav C S
Published: January 2022

The 6H-perovskites Ba3RRu2O9 (R = rare earth element) demonstrate the magnetodielectric (MD) coupling as a manifestation of 4d–4f magnetic interactions. Here, a detailed study of the structural, magnetic, heat capacity, and MD properties of the 6H-perovskite Ba3GdRu2O9 is reported. The signature of long-range antiferromagnetic (AFM) ordering ∼14.8 K (T
N) is evident from the magnetization and heat capacity studies. The T
N shifts towards the lower temperature side, apart from splitting in two with the application of the magnetic field. Field-dependent magnetization at 2 K shows three metamagnetic transitions with the opening of small hysteresis in different regions. A new transition at T
1 emerges after the onset of the first metamagnetic transition. Complex magnetic behavior is observed in different magnetic field regions whereas these field regions themselves vary with the temperature. Dielectric response recorded at zero and 80 kOe field exhibits the development of MD coupling well above T
N. The MD coupling (∼4.5% at 10 K) is enhanced by 25% as compared to the Dy counterpart. Effect of complex magnetic behavior is also conveyed in the MD results where the maximum value of MD coupling is observed in the vicinity of 10 K (onset of T
1) and near the second metamagnetic transition. Our investigation suggests that both Gd and Ru moments align simultaneously at T
N. Short-range magnetic ordering is possibly responsible for MD coupling above T
N.
Performance enhancement of a scanning electron microscope using a deep convolutional neural network
Authors: Panchal Suresh , Datar Suwarna , Gopinathan Unnikrishnan
Published: January 2022

We report noise reduction and image enhancement in scanning electron microscope (SEM) imaging while maintaining a fast scan rate during imaging, using a deep convolutional neural network (D-CNN). SEM images of non-conducting samples without a conducting coating always suffer from charging phenomenon, giving rise to SEM images with low contrast or anomalous contrast and permanent damage to the sample. One of the ways to avoid this effect is to use fast scan mode, which suppresses the charging effect fairly well. Unfortunately, this also introduces noise and gives blurred images. The D-CNN has been used to predict relatively noise-free images as obtained from a slow scan from a noisy, fast scan image. The predicted images from D-CNN have the sharpness of images obtained from a slow scan rate while reducing the charging effect. We show that by using the proposed method it is possible to increase the scanning rate by a factor of about seven with an output of image quality comparable to that of slow scan mode. We present experimental results in support of the proposed method.
Median line-gram and its application in the fault diagnosis of rolling bearing
Authors: Wang Xinglong , Zheng Jinde , Zhang Jun
Published: January 2022

The level selection of frequency band division structure relies on prior information in most gram approaches that capture the optimal demodulation frequency band (ODFB). When an improper level is specified in these approaches, the fault characteristic information contained in the produced ODFB may be insufficient. This study proposes a unique approach, termed median line-gram, to tackle the level selection problem. To divide the frequency domain signal into a series of demodulation frequency bands, a spectrum median-line segmentation model based on Akima interpolation is first created. The level and boundary of the segmentation model can be adaptively identified by this means. Second, the acquired frequency bands are quantized using the negative entropy index, and the ODFB is defined as the frequency band with the largest value. Third, the envelope spectrum is used to determine the ODFB characteristic frequency to pinpoint the bearing fault location. Finally, both simulation and experimental signal analysis are used to demonstrate the efficiency of the suggested method. Furthermore, the proposed method extracts more defect feature information from the ODFB than existing methods.
Simulating intergranular hydrogen enhanced decohesion in aluminium using density functional theory
Authors: Wilson Benjamin T , Robson Joseph D , Shanthraj Pratheek , Race Christopher P
Published: January 2022

Materials modelling at the atomistic scale provides a useful way of investigating the widely debated fundamental mechanisms of hydrogen embrittlement in materials like aluminium alloys. Density functional theory based tensile tests of grain boundaries (GBs) can be used to understand the hydrogen enhanced decohesion mechanism (HEDE). The cohesive zone model was employed to understand intergranular fracture from energies obtained in electronic structure calculations at small separation increments during ab initio tensile tests of an aluminium Σ11 GB supercell with variable coverages of H. The standard rigid grain shift (RGS) test and a quasistatic sequential test, which aims to be faster and more realistic than the RGS method, were implemented. Both methods demonstrated the effects of H on the cohesive strength of the interface. The sequential method showed discrete structural changes during decohesion, along with significant deformation in general compared to the standard rigid approach. H was found to considerably weaken the GB, where increasing H content led to enhanced embrittlement such that, for the highest coverages of H, GB strength was reduced to approximately 20% of the strength of a pure Al GB—it is proposed that these results simulate HEDE. The possibility of finding H coverages required to induce this effect in real alloy systems is discussed in context by using calculations of the heat of segregation of H.
Advancement in fabrication of carbon nanotube tip for atomic force microscope using multi-axis nanomanipulator in scanning electron microscope
Authors: Kanth Sanjeev Kumar , Sharma Anjli , Park Byong Chon , Song Woon , Ruh Hyun , Hong Jaewan
Published: January 2022

We have constructed a new nanomanipulator (NM) in a field emission scanning electron microscope (FE-SEM) to fabricate carbon nanotube (CNT) tip to precisely adjust the length and attachment angle of CNT onto the mother atomic force microscope (AFM) tip. The new NM is composed of 2 modules, each of which has the degree of freedom of three-dimensional rectilinear motion x, y and z and one-dimensional rotational motion θ. The NM is mounted on the stage of a FE-SEM. With the system of 14 axes in total which includes 5 axes of FE-SEM and 9 axes of nano-actuators, it was possible to see CNT tip from both rear and side view about the mother tip. With the help of new NM, the attachment angle error could be reduced down to 0° as seen from both the side and the rear view, as well as, the length of the CNT could be adjusted with the precision using electron beam induced etching. For the proper attachment of CNT on the mother tip surface, the side of the mother tip was milled with focused ion beam. In addition, electron beam induced deposition was used to strengthen the adhesion between CNT and the mother tip. In order to check the structural integrity of fabricated CNT, transmission electron microscope image was taken which showed the fine cutting of CNT and the clean surface as well. Finally, the performance of the fabricated CNT tip was demonstrated by imaging 1-D grating and DNA samples with atomic force microscope in tapping mode.
Thermodynamic formalism for transient dynamics on the real line
Authors: Gröger M , Jaerisch J , Kesseböhmer M
Published: January 2022

We develop a new thermodynamic formalism to investigate the transient behaviour of maps on the real line which are skew-periodic

Z

-extensions of expanding interval maps. Our main focus lies in the dimensional analysis of the recurrent and transient sets as well as in determining the full dimension spectrum with respect to α-escaping sets. Our results provide a one-dimensional model for the phenomenon of a dimension gap occurring for limit sets of Kleinian groups. In particular, we show that a dimension gap occurs if and only if we have non-zero drift and we are able to precisely quantify its width as an application of our new formalism.
Alpha particle microdosimetry calculations using a shallow neural network
Authors: Wagstaff Peter , Gabiña Pablo Mínguez , Mínguez Ricardo , Roeske John C
Published: January 2022

A shallow neural network was trained to accurately calculate the microdosimetric parameters, 〈z
1〉 and 〈z
1
2〉 (the first and second moments of the single-event specific energy spectra, respectively) for use in alpha-particle microdosimetry calculations. The regression network of four inputs and two outputs was created in MATLAB and trained on a data set consisting of both previously published microdosimetric data and recent Monte Carlo simulations. The input data consisted of the alpha-particle energies (3.97–8.78 MeV), cell nuclei radii (2–10 μm), cell radii (2.5–20 μm), and eight different source-target configurations. These configurations included both single cells in suspension and cells in geometric clusters. The mean square error (MSE) was used to measure the performance of the network. The sizes of the hidden layers were chosen to minimize MSE without overfitting. The final neural network consisted of two hidden layers with 13 and 20 nodes, respectively, each with tangential sigmoid transfer functions, and was trained on 1932 data points. The overall training/validation resulted in a MSE = 3.71 × 10−7. A separate testing data set included input values that were not seen by the trained network. The final test on 892 separate data points resulted in a MSE = 2.80 × 10−7. The 95th percentile testing data errors were within ±1.4% for 〈z
1〉 outputs and ±2.8% for 〈z
1
2〉 outputs, respectively. Cell survival was also predicted using actual versus neural network generated microdosimetric moments and showed overall agreement within ±3.5%. In summary, this trained neural network can accurately produce microdosimetric parameters used for the study of alpha-particle emitters. The network can be exported and shared for tests on independent data sets and new calculations.
Collisional radiative model for the evaluation of the thermal helium beam diagnostic at ASDEX upgrade
Authors: Wendler D , Dux R , Fischer R , Griener M , Wolfrum E , Birkenmeier G , Stroth U
Published: January 2022

The thermal helium beam diagnostic at ASDEX Upgrade is used to infer the electron density n

e
and temperature T

e
in the scrape-off layer and the pedestal region from the emission of visible lines of the locally injected helium. The link between n

e
and T

e
and the emission is provided by a collisional radiative model, which delivers the evolution of the populations of the relevant excited states as the He atoms travel through the plasma. A computationally efficient method with just three effective states is shown to provide a good approximation of the population dynamics. It removes an artificial rise of T

e
at the plasma edge when using a simple static model. Furthermore, the re-absorption of the vacuum ultra-violet resonance lines has been introduced as an additional excitation mechanism being mainly important in the region close to the injection point. This extra excitation leads to a much better fit of the measured line ratios in this region for larger puff rates.
Progress in researching the implosion of nested arrays of mixed composition and the generation of soft x-ray power pulse
Authors: Mitrofanov K N , Aleksandrov V V , Branitski A V , Grabovskiy E V , Gritsuk A N , Oleinik G M , Frolov I N , Samokhin A A , Olkhovskaya O G , Gasilov V A
Published: January 2022

The results of experiments on the study of plasma compression of nested wire arrays of mixed composition and the generation of powerful pulses of soft x-ray radiation (SXR), carried out on a pulse power facility Angara-5-1 at a current level of up to 3 MA, are presented. Based on the latest experimental data on the intensity of plasma formation of various substances

m
˙

(in μg(cm2 ns)−1) (Mitrofanov et al 2020 Plasma Phys. Rep.
46 1150–80) and on the features of the dynamics of plasma compression in nested arrays (Mitrofanov et al 2018 Plasma Phys. Rep.
44 203–35), a nested wire array design has been developed which makes it possible to obtain a high peak SXR power in comparison with the known designs of single and nested tungsten wire arrays. During the implosion of nested arrays of mixed composition, consisting of plastic fibers and tungsten wires, shorter and more powerful SXR pulses were obtained with a maximum peak power P
SXR
max∼ 10 TW with a full width at half maximum (FWHM) duration of ∼5 ns compared to the parameters of SXR pulses upon compression of single tungsten arrays: P
SXR
max∼ 5 TW and FWHM ∼ 10 ns. Thus, under the conditions of our experiments, we have shown the possibility of a twofold increase in the peak SXR power during compression of nested arrays by optimizing their design.