bluuebunny/crossref_metadata_2025_split huggingface dataset:
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

SignificanceThe 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

SignificanceIncreasing 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

Abstract

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.
A deterministic breakdown model for dielectric interfaces subjected to tangential electric field
Authors: Kantar Emre , Hvidsten Sverre 
Published: April 2021

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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.
An x-ray crosstalk correction method using FCNN for a novel energy resolving scheme in spectral CT
Authors: Shi Zaifeng , Wang Ziju , Kong Fanning , Cao Qingjie , Wang Ning , Qi Junyu 
Published: April 2021

Abstract
Spectral computed tomography has great potential for multi-energy imaging and anti-artifacts. The complete absorption-based energy resolving scheme of x-rays has been used for the integrity of detected information. However, this scheme is limited by the fact that the detector pixel thickness is high and fixed. Here, an energy resolving scheme is proposed using the crosstalk correction method for the incomplete absorption detection of x-rays. A fully connected neural network (FCNN)-based method was used to correct the difference caused by internal x-ray crosstalk of the edge-on detector. The energy and spatial features of the data which is collected in layers were combined to establish the mapping between the ideal data and the data with crosstalk at the pre-processing stage. Thereafter, to reconstruct the stable and highly accurate energy-resolving equations, the layers with low relative energy difference were selected and grouped together to reduce the accumulation difference. The experiment results demonstrate the feasibility of this energy resolving scheme. The differences caused by crosstalk can be suppressed through the proposed FCNN-based method. The resolving accuracy can be further improved by grouping more layers at forward positions in the pixel. Moreover, this improvement can be observed in the reconstructed images with reduced artifacts and improved quality.
Space-charge induced particle reflection between hybrid AC/DC biased electrodes
Authors: Lafleur T. 
Published: April 2021

Abstract
Space-charge limited current flow between DC biased electrodes is a widely applicable problem in many areas of physics. Recently, radio-frequency biasing, together with DC self-bias formation, has been studied as a new concept for the extraction of charged particles from an upstream plasma source. Here, we compare particle extraction between systems using this hybrid AC/DC biasing, with conventional DC biased electrodes, and identify important similarity parameters. The injection current first leading to particle reflection strongly depends on the applied AC frequency and voltage magnitude, as well as the initial particle injection velocity, and is in general lower than the DC case. For injection currents above the AC limit, the system becomes unstable, and self-excited space-charge oscillations are generated. A critical parameter is the ratio of the average particle transit time between the electrodes to the AC period, γ = t
L/T. As long as γ ≫ 1, the onset of particle reflection can be sufficiently delayed that the extracted current approaches the DC limit.
Localized-state ensemble model analysis of InGaN/GaN quantum well structures with different dislocation densities
Authors: Arteev Dmitri S , Sakharov Alexei V , Zavarin Evgenii E , Lundin Wsevolod V , Rzheutski Mikalai V , Lutsenko Evgenii V , Tsatsulnikov Andrey F 
Published: April 2021

Abstract
The influence of dislocations on luminescence of InGaN/GaN multiple quantum wells was investigated by temperature-dependent and time-resolved room-temperature photoluminescence measurements and analyzed via localized-state ensemble model. The results show that dislocations decrease non-radiative recombination time and do not affect either radiative recombination time or non-radiative recombination mechanism. Moreover, dislocation-related broadening, increasing linearly with increased dislocation density, was found to take place. However, a significant part of spectral width (∼55 meV) is not defined by either dislocation-induced or alloy- and thermally-induced broadening, revealing the existence of other broadening mechanisms (e.g. carrier–carrier scattering-induced broadening).