bluuebunny/crossref_metadata_2025 huggingface dataset:
From “learning from the field” to jointly driving change
Authors: Galjour Joshua , Schwarz Thomas , Rusike Itai , Lomazzi Marta , Hoemeke Laura , Prytherch Helen , Rwafa-Ponela Teurai , Nanyonga Margaret , Ram Ravi M. , Neupane Sunisha , Tsasis Peter , Rumaney Maryam Bibi , Akinmurele Timothy , Ssemakula Michael , Nanda Rituu B. , Mpinga Emmanuel Kabengele
Published: April 2021

The theme of the 8th edition of the Geneva Health Forum (GHF) was Improving access to health: learning from the field. While ‘the field’ often denotes people, patients, communities, and healthcare workers, we challenge the notion and its usage. A group of like-minded conference participants set up a working group to examine the term ‘the field’ and look at questions related to language, power, participation, and rights. By highlighting deficiencies of existing terms and jargon, we explain why language is a form of power that matters in public health. We describe global, regional, and national case studies that facilitate full participation to achieve more equitable health outcomes. By concluding with concrete recommendations, we hope to contribute to these shared goals: to correct power imbalances between health authorities and the people that they intend, and are expected, to serve. The authors are all members of the working group.
Analysis of Dirac and Weyl points in topological semimetals via oscillation effects
Authors: Mikitik G. P. , Sharlai Yu. V.
Published: April 2021

We calculate the extremal cross-sectional areas and cyclotron masses for the Fermi-surface pockets in Dirac and Weyl topological semimetals. The calculation is carried out for the most general form of the electron energy bands in the vicinity of the Weyl and Dirac points. Using the obtained formulas, one can find parameters characterizing the Dirac and Weyl electrons in the topological semimetals from appropriate experimental data. As an example, we consider the W1 electrons in TaAs.
Nonstationary equation for the one-particle wave function of the Bose–Einstein condensate
Authors: Bobrov V. B. , Trigger S. A. , Zagorodny A. G.
Published: April 2021

Based on the self-consistent Hartree–Fock approximation, the nonstationary equation is obtained for the one-particle wave function describing the Bose–Einstein condensate in a rarefied gas of spin-zero bosons. A rarefied gas of bosons is exposed to the static external field, which ensures its finite ground state. The derived equation allows one to correctly determine the ground state energy in the stationary case.
The impact of processing on the optical absorption onset of CdTe thin-films and solar cells
Authors: Andrews J. J. , Beaudoin M. , O’Leary S. K. , Koirala P. , Ramanujam B. , Tan X. , Razooqi Alaani M. A. , Pradhan P. , Podraza N. J. , Collins R. W.
Published: April 2021

We critically examine how two processing steps commonly applied in the preparation of cadmium telluride (CdTe)-based solar cells, i.e., the cadmium chloride treatment and the subsequent stepwise bromine/methanol wet etching process, impact the structural and optical properties of polycrystalline CdTe thin-films. In particular, drawing upon a conjuncture of photothermal deflection spectroscopy and spectroscopic ellipsometry experimental results, we determine the spectral dependence of the optical absorption coefficient, α(E), over the photon energy range from 1.1 to 2.0 eV for samples of rf sputtered (RFS) and close space sublimation (CSS) CdTe. The impact of these processing steps on shaping the grazing incidence x-ray diffraction pattern is also examined. We extend the analysis to devices through interpretation of the spectral dependence of the external quantum efficiency associated with two cadmium chloride treated CdTe-based solar cells. The cells are comparably prepared with the exception of the absorber, one by RFS and the other by CSS. Through the use of our results for the thin-film CdTe optical functions and a model for the solar cell multilayer structure, we simulate the resultant external quantum efficiency spectrum. Through a critical contrast with the corresponding solar cell acquired experimental results, we glean insights into the carrier trapping and recombination processes that occur within the two types of CdTe absorbers.
Fast mobility induced self-lubrication at metallic glass surface
Authors: Lu Yumiao , Liu Xiaodi , Sun Baoan , Cao Chengrong , Pan Mingxiang , Liu Chain Tsuan , Wang Weihua , Yang Yong , Bai Haiyang
Published: April 2021

The enhanced surface mobility in metallic glasses (MGs) has been a constant source of fascination due to its unique mechanical properties. We show experimentally that the mobile surface layer of MGs functions as a lubricating layer in friction experiments, which is evidenced by a reduction of a friction coefficient of 50% or less and suppression of dissipative stick-slip behavior with decreasing scratch depth down to nanoscale in the various MGs. The lubrication mechanism could be attributed to easier shearing of the mobile surface layer induced by homogeneous plastic flow. Importantly, the thickness of the self-lubricating layer is inversely proportional to glass transition temperature with a higher homologous temperature yielding a larger thickness. These results extend the fundamental understanding of the ubiquitous MG surface and present a path for the rational design of self-lubricating materials.
Implementation of synthetic fast-ion loss detector and imaging heavy ion beam probe diagnostics in the 3D hybrid kinetic-MHD code MEGA
Authors: Oyola P. , Gonzalez-Martin J. , Garcia-Munoz M. , Galdon-Quiroga J. , Birkenmeier G. , Viezzer E. , Dominguez-Palacios J. , Rueda-Rueda J. , Rivero-Rodriguez J. F. , Todo Y. ,   ASDEX Upgrade Team
Published: April 2021

A synthetic fast-ion loss (FIL) detector and an imaging Heavy Ion Beam Probe (i-HIBP) have been implemented in the 3D hybrid kinetic-magnetohydrodynamic code MEGA. First synthetic measurements from these two diagnostics have been obtained for neutral beam injection-driven Alfvén Eigenmode (AE) simulated with MEGA. The synthetic FILs show a strong correlation with the AE amplitude. This correlation is observed in the phase-space, represented in coordinates (Pϕ, E), being toroidal canonical momentum and energy, respectively. FILs and the energy exchange diagrams of the confined population are connected with lines of constant E′, a linear combination of E and Pϕ. First i-HIBP synthetic signals also have been computed for the simulated AE, showing displacements in the strike line of the order of ∼1 mm, above the expected resolution in the i-HIBP scintillator of ∼100 μm.
Monte Carlo simulation of electrons injected from a low-temperature plasma into liquid water
Authors: Akiyama N. , Nakagawa Y. , Uchida S. , Tochikubo F.
Published: April 2021

When electrons from a plasma enter a water surface, they collide with the water molecules and lose their energy, eventually becoming hydrated electrons, which are an important species for radical formation in liquid water. Although gas discharge plasmas in contact with water are an easy source of hydrated electrons, their production processes are not clearly understood. In this study, Monte Carlo simulations of electrons in liquid water were performed to investigate the production of a hydrated electron and radical species by low-energy electron irradiation of the water surface from an atmospheric-pressure plasma. The incident electrons were assumed to have a Maxwellian energy distribution with mean electron energy ranging from 1 to 10 eV. The production of hydrated electrons by electron irradiation of 3 eV reached a peak near the gas–liquid interface, and the electrons spread to a depth of approximately 17 nm. OH and H are also generated near the water surface.
Free energies of crystals computed using Einstein crystal with fixed center of mass and differing spring constants
Authors: Khanna Vikram , Anwar Jamshed , Frenkel Daan , Doherty Michael F. , Peters Baron
Published: April 2021

Free energies of crystals computed using a center of mass constraint require a finite-size correction, as shown in previous work by Polson et al. [J. Chem. Phys. 112, 5339–5342 (2000)]. Their reference system is an Einstein crystal with equal spring constants. In this paper, we extend the work of Polson et al. [J. Chem. Phys. 112, 5339–5342 (2000)] to the case of differing spring constants. The generalization is convenient for constraining the center of mass in crystals with atoms of differing masses, and it helps to optimize the free energy calculations. To test the theory, we compare the free energies of LiI and NaCl crystals from calculations with differing spring constants to those computed using equal spring constants. Using these center of mass finite size corrections, we compute the true free energies of these crystals for different system sizes to eliminate the intrinsic finite-size effects. These calculations help demonstrate the size of these finite-size corrections relative to other contributions to the absolute free energy of the crystals.
Deflection of a bubble pair induced by negative magnetophoresis in a Hele-Shaw cell
Authors: Li Qian , He Yongqing , Liu Jinghan , Jiao Feng
Published: April 2021

To explore how a magnetic field act on the motion of a bubble pair suspended in a ferrofluid, we introduce an “effective magnetic dipole” to represent the air bubble and further solve the two-dimensional Laplace's equation to obtain the distribution of magnetic potential. The derived magnetic interaction force has two components. The tangential one allows the bubble pair to deflect to be parallel to the magnetic field, where the deflection is clockwise at an angle less than 90°. Inversely, it is counterclockwise. The radial component appears as attraction or repulsion depending on the relative position, which switches from attraction to repulsion at critical angles θc = 55° and 125°. Meanwhile, we performed a simple verification experiment in a Hele–Shaw cell to evaluate the deflection angle and spacing of the bubble pair, and the results are in good agreement with the model. This technique has promise in bubble manipulation for microfluidics.
Opportunities and utilization of branching and step-out behavior in magnetic microswimmers with a nonlinear response
Authors: Bachmann Felix , Giltinan Joshua , Codutti Agnese , Klumpp Stefan , Sitti Metin , Faivre Damien
Published: April 2021

Microswimmers are smart devices with potential applications in medicine and biotechnology at the micrometer-scale. Magnetic micropropellers with their remote control via rotating magnetic fields are especially auspicious. Helicoidal propellers with a linear velocity–frequency dependence emerged as the standard propulsion mechanism over the last decade. However, with their functions becoming more pivotal on the way to practical uses, deviations in shape and swimming behavior are inevitable. Consequently, propellers with nonlinear velocity–frequency relationships arise that not only pose different challenges but also offer advanced possibilities. The most critical nonlinearities are the wobbling behavior with its solution branching that has potential for bimodal swimming and the swimming characteristics in the step-out regime that are essential for selection and swarm control. Here, we show experimentally and with numerical calculations how the previously unpredictable branching can be controlled and, thus, becomes utilizable with an example 3D-printed swimmer device. Additionally, we report how two step-out modes arise for propellers with a nonlinear velocity–frequency dependence that have the potential to accelerate future microswimmer sorting procedures.
Stimulus induced strain in spin transition heterostructures
Authors: Cain John M. , He Wanhong , Maurin Isabelle , Meisel Mark W. , Talham Daniel R.
Published: April 2021

Strain is often used to alter material properties in applications ranging from bandgap tuning for semiconductor electronics to performing work through mechanical actuation. Spin transitions are accompanied by volume changes in the solid state and are being explored in actuation as a source of mechanical strain inducible by the many controllable stimuli known to trigger spin state changes. There is still much to understand, especially at small length scales, about how strain is transmitted from one material to another across a mechanically coupled interface. Theoretical efforts modeling spin-transition particles in a matrix provide significant insights, but this remains an area where systematic experimental studies are limited. This Perspective highlights the progress using cobalt hexacyanoferrate network solids, or Prussian blue analogues (CoFe-PBA), as a framework for investigating spin transition induced strain in nanometer scale and mesoscale heterostructures. Using a family of isostructural cyanometallate networks to form heterostructures with well-defined interfaces, measurements of the altered properties in response to strain generated by the thermally or optically induced spin state change of the CoFe-PBA provide the chance to experimentally interrogate factors that control interface transmitted strain.
Non-Newtonian power-law fluid flow over obstacles embedded inside a cavity
Authors: Bisht Manju , Kumar Pradeep , Patil Dhiraj V.
Published: April 2021

In this study, the flow of non-Newtonian fluid inside the lid-driven cavity with obstacle(s) is examined. The behavior of the fluid is described by the Ostwald-de Waele or power-law model. The lattice Boltzmann method (LBM) with a multiple-relaxation-time (MRT) collision model is employed to simulate complex fluid flows around the circular and square obstacles embedded inside a cavity. The stability of the present MRT-LBM algorithm in terms of so-called, cell-Reynolds number is investigated. The physics of flow structure and examinations of streamlines and vorticity contours are carried out for power-law as well as Newtonian fluids. For a single obstacle, the effects of various parameters such as Reynolds number (with respect to lid-dimension), obstacle size, power-law index, and shape of the obstacle on the flow characteristics and vortex formation are investigated. Furthermore, the effect of two square obstacles arranged in side-by-side and tandem manners inside the cavity is analyzed. Finally, the complex fluid flow over the multiple square obstacles embedded inside the cavity as a porous block for two blockage ratios is examined.
Suppression of thermal conductivity and electronic correlations in Fe1−xRuxSb2 (0 ≤x≤ 0.6)
Authors: Du Qianheng , Tong Xiao , Liu Yu , Petrovic C.
Published: April 2021

We present simultaneous suppression of FeSb2 thermal conductivity and electronic correlations in Fe1−xRuxSb2 (0 ≤x≤ 0.6) single crystal alloys. Small energy gap Δ1 in Kondo-insulator-like semiconductor FeSb2 associated with impurity in-gap state increases whereas the intrinsic bandgap Δ2 decreases upon Ru substitution on Fe atomic site. Thermopower is suppressed along with the intrinsic bandgap and with the thermal conductivity. The more delocalized 4d character of atomic orbital of Ru brings suppression of electronic correlations, but also an increase in impurity density which reduces phonon mean free path and surface scattering length. Our results indicate a range of Ru doping x where nanostructuring could be used to suppress thermal conductivity further, potentially toward the amorphous limit.
Extreme ultraviolet photoemission of a tin-based photoresist
Authors: Zhang Yu , Haitjema Jarich , Castellanos Sonia , Lugier Olivier , Sadegh Najmeh , Ovsyannikov Ruslan , Giangrisostomi Erika , Johansson Fredrik O. L. , Berggren Elin , Lindblad Andreas , Brouwer Albert M.
Published: April 2021

Tin is a suitable element for inclusion in extreme ultraviolet photoresists because of its relatively high-absorption cross section at 92 eV. The electrons emitted after photon absorption are expected to generate secondary electrons in the solid film. In this way, several pathways lead to reactive species that cause a solubility switch. Here, we report the photoelectron spectra of tin oxo cage photoresists over the photon energy range 60–150 eV, and the relative yields of photoelectrons from the valence band of the resist, from the Sn 4d orbitals, and of inelastically scattered electrons. The experimental excitation spectra differ considerably from those predicted by commonly used database cross section values, and from the combined computed subshell spectra: the maximum efficiency of ionization of Sn 4d both in the photoresists and in Sn metal occurs near the industrially relevant EUV wavelength of 13.5 nm.
Vortex dynamics and fractal structures in reactive and nonreactive Richtmyer–Meshkov instability
Authors: Bambauer M. , Chakraborty N. , Klein M. , Hasslberger J.
Published: April 2021

Hydrodynamic instabilities caused by shock-flame interactions are a fundamental challenge in the accurate prediction of explosion loads in the context of nuclear and process plant safety. To investigate the Richtmyer–Meshkov instability, a series of three-dimensional numerical simulations of shock-flame interactions are performed, including lean, stoichiometric, and nonreactive homogeneous H2/Air mixtures. The equivalence ratio has a strong influence on the achievable flame wrinkling and mixing, by impacting key physical parameters such as the heat release parameter, flame thickness, and reactivity. The reactivity is found to be a decisive factor in the evolution of the wrinkled flame brush, as it can cause burnout of the developing fresh gas cusps and wrinkled structures. The importance of reactivity is further emphasized by comparisons to a nonreactive case. Analysis of the enstrophy (energy equivalent of vorticity) transport terms shows that baroclinic torque is dominant during shock-flame interactions. After the shock interaction, the vortex stretching, dissipation, and dilatation terms gain in importance significantly. A power-law based modeling approach of the flame wrinkling is investigated by explicitly filtering the present simulation data. The values determined for the fractal dimension show a nonlinear dependency on the chosen equivalence ratio, whereas the inner cutoff scale is found to be approximately independent of the equivalence ratio for the investigated cases.
Efficacy of face coverings in reducing transmission of COVID-19: Calculations based on models of droplet capture
Authors: Robinson Joshua F. , Rios de Anda Ioatzin , Moore Fergus J. , Reid Jonathan P. , Sear Richard P. , Royall C. Patrick
Published: April 2021

In the COVID-19 pandemic, among the more controversial issues is the use of masks and face coverings. Much of the concern boils down to the question—just how effective are face coverings? One means to address this question is to review our understanding of the physical mechanisms by which masks and coverings operate—steric interception, inertial impaction, diffusion, and electrostatic capture. We enquire as to what extent these can be used to predict the efficacy of coverings. We combine the predictions of the models of these mechanisms which exist in the filtration literature and compare the predictions with recent experiments and lattice Boltzmann simulations, and find reasonable agreement with the former and good agreement with the latter. Building on these results, we explore the parameter space for woven cotton fabrics to show that three-layered cloth masks can be constructed with comparable filtration performance to surgical masks under ideal conditions. Reusable cloth masks thus present an environmentally friendly alternative to surgical masks so long as the face seal is adequate enough to minimize leakage.
On the coupling between ionic conduction and dipolar relaxation in deep eutectic solvents: Influence of hydration and glassy dynamics
Authors: Jani Aicha , Malfait Benjamin , Morineau Denis
Published: April 2021

We have studied the ionic conductivity and the dipolar reorientational dynamics of aqueous solutions of a prototypical deep eutectic solvent (DES), ethaline, by dielectric spectroscopy in a broad range of frequencies (MHz–Hz) and for temperatures ranging from 128 to 283 K. The fraction of water in the DES was varied systematically to cover different regimes, starting from the pure DES and its water-in-DES mixtures to the diluted electrolyte solutions. Depending on these parameters, different physical states were examined, including low viscosity liquid, supercooled viscous liquid, amorphous solid, and freeze-concentrated solution. Both the ionic conductivity and the reorientational relaxation exhibited characteristic features of glassy dynamics that could be quantified from the deviation from the Arrhenius temperature dependence and non-exponential decay of the relaxation function. A transition occurred between the water-in-DES regime (<40 wt. %), where the dipolar relaxation and ionic conductivity remained inversely proportional to each other, and the DES-in-water regime (>40 wt. %), where a clear rotation–translation decoupling was observed. This suggests that for a low water content, on the timescale covered by this study (∼10−6 to 1 s), the rotational and transport properties of ethaline aqueous solutions obey classical hydrodynamic scaling despite these systems being presumably spatially microheterogeneous. A fractional scaling is observed in the DES-in-water regime due to the formation of a maximally freeze-concentrated DES aqueous solution coexisting with frozen water domains at sub-ambient temperature.
Interrupting vaccination policies can greatly spread SARS-CoV-2 and enhance mortality from COVID-19 disease: The AstraZeneca case for France and Italy
Authors: Faranda Davide , Alberti Tommaso , Arutkin Maxence , Lembo Valerio , Lucarini Valerio
Published: April 2021

Several European countries have suspended the inoculation of the AstraZeneca vaccine out of suspicion that it causes deep vein thrombosis. In this letter, we report some Fermi estimates performed using a stochastic model aimed at making a risk–benefit analysis of the interruption of the delivery of the AstraZeneca vaccine in France and Italy. Our results clearly show that excess deaths due to the interruption of the vaccination campaign injections largely overrun those due to thrombosis even in worst case scenarios of frequency and gravity of the vaccine side effects.
Use of complex fully connected neural networks to compensate for nonlinear effects in fibre-optic communication lines
Authors: Bogdanov S.A. , Sidelnikov O.S.
Published: April 2021

A scheme is proposed for processing optical signals in a receiver of a communication system, based on complex fully connected neural networks. The influence of the main characteristics of the neural network on the efficiency of nonlinear distortion compensation is studied. A significant advantage of the proposed scheme over real-valued neural networks is demonstrated.
Analysis of the applicability of the classical probabilistic parameters of the Monte Carlo algorithm for problems of light transport in turbid biological media with continuous absorption and discrete scattering
Authors: Tarasov A.P. , Persheyev S. , Rogatkin D.A.
Published: April 2021

Simulation of light propagation by the statistical Monte Carlo (MC) method is widely used in many fields, especially in astrophysics, atmospheric optics, ocean optics, and nuclear medicine. In the optics of biological tissues, the MC method is used to simulate the luminous flux, which is formed during various medical therapeutic or diagnostic procedures inside a biological tissue and on its surface. In such calculations, the MC method is commonly considered as a reference one, which ensures an arbitrarily high accuracy with an increase in the number of ‘photons’. However, it can be shown that this is not always the case. In this paper, in the methodological aspect, the idealised one-dimensional problems of the transport theory for a turbid medium with continuous absorption and scattering and a turbid medium with discrete scatterers inside a continuously absorbing medium are considered. Their exact analytical solutions are presented and compared with the results of statistical modelling by the MC method. It is found that the use of classical probabilistic parameters for a medium with continuous absorption and scattering in the MC algorithm leads to a systematic method error in determining the values of radiation fluxes for biological media with discrete scattering, up to 10% for fluxes at the boundary in some cases. The causes of the error are discussed and it is shown how to modify the probabilistic parameters of the MC algorithm to eliminate it.
High-frequency pulse train generation in dispersion-decreasing fibre: using experimental data for the metrology of longitudinally nonuniform fibre
Authors: Panyaev I.S. , Stoliarov D.A. , Sysolyatin A.A. , Zolotovskii I.O. , Korobko D.A.
Published: April 2021

This paper describes experiments concerned with pulse train generation from initially modulated cw light in an anomalous dispersion decreasing fibre. We have obtained stable contrast trains of subpicosecond pulses with a repetition rate in the range 100 – 300 GHz and demonstrated generation of an optical comb spectrum with a –20-dB width of up to 80 nm. A method has been proposed for reconstructing an unknown dispersion profile of a longitudinally nonuniform fibre by comparing experimental data and numerical simulation results.
Vertical Transmission
Authors: Lyras Dena
Published: April 2021

Since this is my first communication with you this year I will start by wishing you all a happy new year and extend my best wishes to all of you for 2021.
High-throughput functional variant screens via in vivo production of single-stranded DNA
Authors: Schubert Max G. , Goodman Daniel B. , Wannier Timothy M. , Kaur Divjot , Farzadfard Fahim , Lu Timothy K. , Shipman Seth L. , Church George M.
Published: April 2021

Significance

We report a methodology for the pooled construction of mutants bearing precise genomic sequence variations and multiplex phenotypic characterization of these mutants using next-generation sequencing (NGS). Unlike existing techniques depending on CRISPR-Cas–directed genomic breaks for genome editing, this strategy instead uses single-stranded DNA produced by a retron element for recombineering. This enables libraries of millions of elements to be constructed and offers relaxed design constraints which permit natural DNA or random variation to be used as inputs.
Blood–brain barrier opening by intracarotid artery hyperosmolar mannitol induces sterile inflammatory and innate immune responses
Authors: Burks Scott R. , Kersch Cymon N. , Witko Jaclyn A. , Pagel Michael A. , Sundby Maggie , Muldoon Leslie L. , Neuwelt Edward A. , Frank Joseph A.
Published: April 2021

Significance

Disruption of the blood–brain barrier (BBB) for drug delivery to the central nervous system (CNS) is achieved clinically through intracarotid artery hyperosmotic mannitol (ICAHM) infusions. However, ICAHM is often viewed as a simple drug delivery mechanism, and biological implications have been largely overlooked. This study demonstrates that BBB disruption by ICAHM generates a transient sterile neuroinflammatory response marked by increased production of cytokines, chemokines, and trophic factors leading activation of astrocytes, microglia, and macrophages. Additionally, unilateral ICAHM generates plasma increases in inflammatory molecules with evidence of sterile inflammation on the untreated contralateral hemisphere. These biological responses to ICAHM suggest its potential for immune modulation in several CNS pathologies.
Redox control on the tungsten isotope composition of seawater
Authors: Kurzweil Florian , Archer Corey , Wille Martin , Schoenberg Ronny , Münker Carsten , Dellwig Olaf
Published: April 2021

Significance

The fate and transport of tungsten (W) in aquatic environments is still poorly constrained. To identify the processes that control the abundance of dissolved W, we applied a sophisticated analytical approach that enables the accurate determination of the seawater W isotopic composition. Our results indicate that the removal of W from seawater mainly occurs via adsorption onto oxide minerals. The marine inventory of W is therefore intimately linked to the areal extension of oxic marine conditions. Concurrently, the limited scavenging of W in anoxic marine settings seems a unique characteristic of W, highlighting that W isotopes can help to reconstruct the earliest rise of oceanic oxygen in Earth’s history.
Adaptive differentiation and rapid evolution of a soil bacterium along a climate gradient
Authors: Chase Alexander B. , Weihe Claudia , Martiny Jennifer B. H.
Published: April 2021

Significance

Increasing evidence suggests that evolutionary processes frequently shape ecological patterns; however, most microbiome studies thus far have focused on only the ecological responses of these communities. By using parallel field experiments and focusing in on a model soil bacterium, we showed that bacterial “species” are differentially adapted to local climates, leading to changes in their composition. Furthermore, we detected strain-level evolution, providing direct evidence that both ecological and evolutionary processes operate on annual timescales. The consideration of eco-evolutionary dynamics may therefore be important to understand the response of soil microbiomes to future environmental change.
Polypogon monspeliensis (annual beard grass).
Authors: Popay Ian
Published: April 2021

Polypogon monspeliensis is a grass that is native to parts of Europe, Asia and northern Africa, and has been introduced to North and South America, some countries in Africa, Australia, New Zealand and a number of islands. It is considered invasive in parts of its introduced range, such as Australia and the western USA, because it can form dense swards that crowd out native plants and prevent their regeneration (Weber, 2003). It is one of several grasses that invade other vegetation (introduced and native) along waterways, roadsides, grassland, etc., and which displace other species to a greater or lesser extent. It can be an agricultural weed, for example in India where it is considered important.
Ficus elastica (rubber plant).
Authors: Datiles Marianne Jennifer , Acevedo-Rodríguez Pedro
Published: April 2021

A datasheet on Ficus elastica covering, as an economically important tree, its taxonomy, importance, silviculture, distribution, biology and ecology, uses, products and pests.
A deterministic breakdown model for dielectric interfaces subjected to tangential electric field
Authors: Kantar Emre , Hvidsten Sverre
Published: April 2021

The contact area between solid insulations, namely solid–solid interfaces, affect the dielectric characteristics of an entire insulation system. With the theoretical and experimental studies covered in this paper, we intend to investigate the effects of the elastic modulus, interface contact pressure, and surface smoothness/roughness on the tangential alternating current (AC) breakdown strength of contact surfaces at dielectric interfaces that undergo a tangential electric field. Four distinct solid dielectric specimens with various elastic modulus values were employed. The interfaces between the same materials were subjected to AC breakdown and partial discharge (PD) tests at different contact pressure values. In addition, the interface surfaces were polished using four different sandpapers of various grits to scrutinize the effect of surface roughness. A deterministic model built around the tribology of solid surfaces was proposed to determine the sizes of the interfacial cavities and to simulate the 3D displacement and deformation of the surface protrusions based on the surface roughness, contact pressure, elastic modulus, and hardness of an interface. The estimated sizes of cavities and contact areas were then coupled with a comprehensive breakdown model that addressed the cavity discharge and breakdown of contact areas, separately. Finally, the results by the model were correlated with the results of the AC breakdown and PD experiments to elucidate not only how cavities were linked at solid–solid interfaces but also the effects of roughness, elasticity, contact pressure, and gas pressure inside of the cavities.
Numerical investigation on the influence of metal particles on the characteristics of a high-current vacuum arc
Authors: Zhao Lihua , Chen Weiwei , Huang Xiaolong , Ren Junwen , Ning Wenjun , Wang Lijun , Zhuang Huimin , Wu Qingzhou
Published: April 2021

In the arc-burning process of a high-current vacuum arc (HCVA), the metal particles (MPs) splashed from the active anode will have a significant influence on the plasma characteristics of the arc column. In this paper, the influence of varying MPs on the characteristics of HCVA are studied by establishing a HCVA model containing single or multiple MPs. The simulation results show that when the MPs vaporized metal vapor (MV) enters the interelectrode region and once the arc column plasma cannot ionize all atoms immediately, the ionization layer and the neutral atom vapor area (NAVA) will be formed in the adjacent region of the MPs. When the MP diameter and temperature increase, the number of vaporized metal atoms increases, so that the influence range of MV increases, and the area of ionization layer and the NAVA increases. In addition, when the arc current increases or the MPs are closer to the cathode surface, the greater the ion number density and ion pressure around the MPs are, the stronger the compression on the MV will be, resulting in the decrease of the area of ionization layer and the neutral atom vapor, and the increase of the net ionization rate of the ion number density. When multiple MPs exist in the interelectrode region at the same time, the MV from the MPs will affect each other. In the central region of multiple MPs, the density of MV becomes the largest, while the net ionization rate of ion number density is distributed in the periphery region of the MP group.
Quantitative phase microscopy using quadriwave lateral shearing interferometry (QLSI): principle, terminology, algorithm and grating shadow description
Authors: Baffou Guillaume
Published: April 2021

Quadriwave lateral shearing interferometry (QLSI) is a quantitative phase imaging technique based on the use of a diffraction grating placed in front of a camera. This grating creates a wire-mesh-like image, called an interferogram, that is postprocessed to retrieve both the intensity and phase profiles of an incoming light beam. Invented in the 90s, QLSI has been used in numerous applications, e.g. laser beam characterization, lens metrology, topography measurements, adaptive optics, and gas jet metrology. More recently, the technique has been implemented in optical microscopes to characterize micro and nano-objects for bioimaging and nanophotonics applications. However, not much effort has been placed on disseminating this powerful technology so far, while it is yet a particularly simple technique. In this article, we intend to popularize this technique by describing all its facets in the framework of optical microscopy, namely the working principle, its implementation on a microscope and the theory of image formation, using simple pictures. We also provide and comment on an algorithm for interferogram processing, written in Matlab. Then, following the new extension of the technique for microscopy and nanophotonics applications, and the deviation from what the technique was initially invented for, we propose to revisit the description of the technique, in particular, by discussing the terminology, insisting more on a grating-shadow description rather than a quadriwave process, and proposing an alternative appellation, namely ‘grating shadow phase microscopy’ or ‘grating-assisted phase microscopy’.
Growth-mode and interface structure of epitaxial ultrathin MgO/Ag(001) films
Authors: De Santis M , Langlais V , Schneider K , Torrelles X
Published: April 2021

MgO ultrathin films are of great technological importance as electron tunneling barrier in electronics and spintronics, and as template for metallic clusters in catalysis and for molecular networks for 2D electronics. The wide band-gap of MgO allows for a very effective decoupling from the substrate. The films morphology and the detailed structure of the interface are crucial for applications, controlling the electronic transfer. Using surface x-ray diffraction, we studied the growth-mode and the structure of MgO/Ag(001) ultrathin films elaborated by reactive molecular beam epitaxy as function of the substrate temperature. We observed that deposition of about 1 monolayer results in an MgO(001) film in coherent epitaxy, with the oxygen atoms on top of silver as predicted by DFT calculations, and an interlayer distance at the interface of about 270 pm. Under well-defined conditions, a sharp MgO bilayer is formed covering a fraction of the substrate surface.
Thermal neutron cross sections of amino acids from average contributions of functional groups
Authors: Romanelli Giovanni , Onorati Dalila , Ulpiani Pierfrancesco , Cancelli Stephanie , Perelli-Cippo Enrico , Márquez Damián José Ignacio , Capelli Silvia C , Croci Gabriele , Muraro Andrea , Tardocchi Marco , Gorini Giuseppe , Andreani Carla , Senesi Roberto
Published: April 2021

The experimental thermal neutron cross sections of the 20 proteinogenic amino acids have been measured over the incident-neutron energy range spanning from 1 meV to 10 keV and data have been interpreted using the multi-phonon expansion based on first-principles calculations. The scattering cross section, dominated by the incoherent inelastic contribution from the hydrogen atoms, can be rationalised in terms of the average contributions of different functional groups, thus neglecting their correlation. These results can be used for modelling the total neutron cross sections of complex organic systems like proteins, muscles, or human tissues from a limited number of starting input functions. This simplification is of crucial importance for fine-tuning of transport simulations used in medical applications, including boron neutron capture therapy as well as secondary neutrons-emission induced during proton therapy. Moreover, the parametrized neutron cross sections allow a better treatment of neutron scattering experiments, providing detailed sample self-attenuation corrections for a variety of biological and soft-matter systems.
Evolution from sinusoidal to collinear A-type antiferromagnetic spin-ordered magnetic phase transition in Tb1−x
Pr
x
MnO3 solid solution
Authors: Agarwal Harshit , Alonso José Antonio , Muñoz Ángel , Choudhary R J , Srivastava O N , Shaz M A
Published: April 2021

The present study reports on the structural and magnetic phase transitions in Pr-doped polycrystalline Tb0.6Pr0.4MnO3, using high-resolution neutron powder diffraction (NPD) collected at SINQ spallation source, to emphasize the suppression of the sinusoidal magnetic structure of pure TbMnO3 and the evolution to a collinear A-type antiferromagnetic ordering. The phase purity, Jahn–Teller distortion, and one-electron bandwidth for eg orbital of Mn3+ cation have been calculated for polycrystalline Tb0.6Pr0.4MnO3, in comparison to the parent materials TbMnO3 and PrMnO3, through the Rietveld refinement study from x-ray diffraction data at room temperature, which reveals the GdFeO3 type orthorhombic structure of Tb0.6Pr0.4MnO3 having Pnma space group symmetry. The temperature-dependent zero field-cooled and field-cooled dc magnetization study at low temperature down to 5 K reveals a variation in the magnetic phase transition due to the effect of Pr3+ substitution at the Tb3+ site, which gives the signature of the antiferromagnetic nature of the sample, with a weak ferromagnetic component at low temperature-induced by an external magnetic field. The field-dependent magnetization study at low temperatures gives the weak coercivity having the order of 2 kOe, which is expected due to the canted-spin arrangement or ferromagnetic nature of Terbium ordering. The NPD data for Tb0.6Pr0.4MnO3 confirms that the nuclear structure of the synthesized sample maintains its orthorhombic symmetry down to 1.5 K. Also, the magnetic structures have been solved at 50 K, 25 K, and 1.5 K through the NPD study, which shows an A-type antiferromagnetic spin arrangement having the magnetic space group Pn′ma′.
High-resolution remote sensing image semantic segmentation based on a deep feature aggregation network
Authors: Wang Zhen , Guo Jianxin , Huang Wenzhun , Zhang Shanwen
Published: April 2021

Semantic segmentation of high-resolution remote sensing images has a wide range of applications, such as territorial planning, geographic monitoring and smart cities. The proper operation of semantic segmentation for remote sensing images remains challenging due to the complex and diverse transitions between different ground areas. Although several convolution neural networks (CNNs) have been developed for remote sensing semantic segmentation, the performance of CNNs is far from the expected target. This study presents a deep feature aggregation network (DFANet) for remote sensing image semantic segmentation. It is composed of a basic feature representation layer, an intermediate feature aggregation layer, a deep feature aggregation layer and a feature aggregation module (FAM). Specially, the basic feature representation layer is used to obtain feature maps with different resolutions: the intermediate feature aggregation layer and deep feature aggregation layer can fuse various resolution features and multi-scale features; the FAM is used to splice the features and form more abundant spatial feature maps; and the conditional random field module is used to optimize semantic segmentation results. We have performed extensive experiments on the ISPRS two-dimensional Vaihingen and Potsdam remote sensing image datasets and compared the proposed method with several variations of semantic segmentation networks. The experimental results show that DFANet outperforms the other state-of-the-art approaches.
Single-projection reconstruction technique for positioning monodisperse spheres in 3D with a divergent x-ray beam
Authors: Andò Edward , Marks Benjy , Roux Stéphane
Published: April 2021

The measurement of the position of single-sized spheres in 3D from a single, divergent, radiographic projection is addressed in the present study with the development of a novel method. Generally speaking, the location of the shadow cast by a single sphere on a detector defines a source-detector ray; the position of the particle along this ray is identified by the strong prior knowledge of its radius and the size of the shadow. For a dense assembly of equal-sized particles whose projections overlap, a novel Fourier transform based technique is introduced to give a first 3D determination of the particle centres. The uncertainty of this measurement is calculated from synthetic data with a known noise distribution. A further refinement of this measurement is performed based on the minimisation of the projection residual. The combined approach is validated both on synthetic data, and on real radiographs of a glass bead packing. The effect of noise on the measurement uncertainty is evaluated. The technique is made available to the community in the open source python package radioSphere.
Effects of high pressure oxygen annealing on Hf0.5Zr0.5O2 ferroelectric device
Authors: Kim Hyungwoo , Kashir Alireza , Oh Seungyeol , Jang Hojung , Hwang Hyunsang
Published: April 2021

We report a high-pressure oxygen annealing (HPOA) process to improve the performance of TiN/Hf0.5Zr0.5O2 (HZO)/TiN devices by controlling the number of oxygen vacancies and carbon contaminants. The ferroelectric properties of HZO film after HPOA at 250 °C for 30 min under different oxygen pressures from 0 to 80 bar were evaluated by electrical and structural characterizations. We found that a sample treated with an oxygen pressure at 40 bar exhibited large switchable polarization (2Pr) of approximately 38 and 47 μC cm−2 in its pristine and wake-up states, respectively. Compared to a control sample, an approximately 40% reduction in the wake-up effect was achieved after HPOA at 40 bar. Improved ferroelectric properties of HZO film can be explained by the appropriate amount of oxygen vacancies and reduced carbon contaminants after HPOA.
A simple method to estimate the mean number of lipophilic molecules on nanoparticle surfaces by fluorescence measurements
Authors: Adura Carolina , Aliaga Carolina , Silva Francisco , Vera Cristian , Pino Eduardo , Celis Freddy , Aracena Andrés , Tirapegui Cristian
Published: April 2021

Measurements of fluorescence intensity of the hydrophobic pyridinium salt (DTPSH) remaining in the organic phase after partition experiments in the DCM/H2O system allowed an approximate method to be developed to estimate the mean number of molecules (N = 942) on the surface of 22.8 nm gold nanoparticles and the separation (1.89 nm) between these organic molecules. This protocol is based on the ability that the organic molecules possess to coat the surface of the nanoparticle, which can migrate from the organic to the aqueous phase as a result of the driving force of the strong binding of sulfur to gold. To validate our estimation, we used a projection of the results obtained by Wales and Ulker to solve the Thomson problem, a mathematicians’ challenge, used as a model to calculate the mean distance (1.82 nm) separating particles on the surface, in excellent agreement with the results obtained by our method. The quality of results, the simplicity of calculations, the low fluorescence detection limit, and the inexpensive materials, recommend this procedure for rapid estimates of the mean number of molecules on the surface of nanoparticles.
Novel aluminum vanadate as a cathode material for high-performance aqueous zinc-ion batteries
Authors: Liu Gangyuan , Xiao Yao , Zhang Wenwei , Tang Wen , Zuo Chunli , Zhang Peiping , Dong Shijie , Luo Ping
Published: April 2021

Rechargeable aqueous zinc-ion batteries (AZIBs) have garnered widespread attention as a new large-scale energy storage candidate owing to their low cost and high theoretical capacity. Because of the unique divalent state of Zn2+ and the existence of a strong electrostatic repulsion phenomenon, researchers are currently focusing on how to prepare high-performance cathode materials. In this study, we synthesized aluminum vanadate (AlV3O9) as a cathode material for AZIBs using a solvothermal method. Al3+ acted as a pillar in the resultant structure and stabilized it. Furthermore, this large interlayer spacing enhanced the ion diffusion coefficient and accelerated the ion transport process. Because of these advantages, the AlV3O9 (AVO) cathode exhibited excellent electrochemical performance, including a high capacity of 421.0 mA h g−1 at 0.1 A g−1 and a stable rate capability of 348.2 mA h g−1 at 1 A g−1. Moreover, it exhibited a specific capacity of 202 mA h g−1 even at a high current density of 3 A g−1 (the capacity retention rate reached 84.38% after 1600 cycles). The prepared ZIBs presented a high power density of 366.6 W kg−1 at an energy density of 286 W h kg−1. These extraordinary results indicate the great application potential of AVO as a cathode material for AZIBs.