bluuebunny/crossref_metadata_2025 huggingface dataset:
Validation of edge turbulence codes in a magnetic X-point scenario in TORPEX
Authors: Galassi D. , Theiler C. , Body T. , Manke F. , Micheletti P. , Omotani J. , Wiesenberger M. , Baquero-Ruiz M. , Furno I. , Giacomin M. , Laribi E. , Militello F. , Ricci P. , Stegmeir A. , Tamain P. , Bufferand H. , Ciraolo G. , De Oliveira H. , Fasoli A. , Naulin V. , Newton S. L. , Offeddu N. , Oliveira D. S. , Serre E. , Vianello N.
Published: January 2022

Transport processes around the magnetic X-point of tokamaks, such as turbulence and mean-field drifts, are scarcely understood. The assessment of the capability of turbulence codes to quantitatively reproduce these dynamics has been hampered by limitations in computational power and available experimental data. In this paper, we present a rigorous validation of full-scale simulations of a newly developed X-point scenario in the basic toroidal plasma device TORPEX, performed with the four state-of-the-art codes FELTOR, GBS, GRILLIX, and STORM. High-resolution Langmuir probe array measurements of various time-averaged and fluctuating quantities and across the entire cross section of TORPEX show that this X-point scenario features the key ingredients of X-point dynamics, such as small-scale fluctuations and background drifts. The codes are able to qualitatively reproduce some characteristics of the time-averaged fields, such as the ion saturation current profiles at mid-height, the plasma up-down asymmetry, and the blob trajectories. A quantitative agreement is found for the background E × B velocity pattern, while the fluctuation levels are generally underestimated typically by factors of 2 or more, and thus, background fluxes are found to dominate over turbulent ones in simulations. The sensitivity of the simulation results on the plasma collisionality and on the position of the sources is tested in GBS, showing a mild effect on the overall quantitative agreement with the experiment. Overall, this validation reveals the challenges to reproduce the plasma dynamics near an X-point and provides a clear path to a quantitative and computationally relatively inexpensive assessment of future developments in turbulence codes.
Ultrafast electron dynamics in platinum and gold thin films driven by optical and terahertz fields
Authors: Unikandanunni V. , Rigoni F. , Hoffmann M. C. , Vavassori P. , Urazhdin S. , Bonetti S.
Published: January 2022

We investigate the ultrafast electron dynamics triggered by terahertz and optical pulses in thin platinum and gold films by probing their transient optical reflectivity. The response of the platinum film to an intense terahertz pulse is similar to the optically induced one and can be described by a two-temperature model with a 20% larger electron–phonon coupling for the terahertz-driven dynamics compared to the optically induced one, ascribed to an additional nonthermal electron–phonon coupling contribution. Surprisingly, gold films exhibit a much smaller terahertz pulse-induced reflectivity change and with a sign opposite to the optical case. We explain this remarkable observation with field emission of electrons due to Fowler–Nordheim tunneling, enabled in samples with thicknesses below the structural percolation threshold, where nanostructuring promotes near-field enhancement. Our results provide a fundamental insight into the ultrafast processes relevant to modern electro- and magneto-optical applications.
Transducerless time domain reflectance measurement of semiconductor thermal properties
Authors: Warkander Sorren , Wu Junqiao
Published: January 2022

The dominant techniques for laser-based thermal measurement, time-domain thermoreflectance (TDTR) and frequency-domain thermoreflectance, generally require that samples be coated with a metal transducer layer. The properties of the transducer and its interface to the sample are then important to the interpretation of results, and heat conduction in the transducer layer can limit measurements of ultra-thin samples or in-plane conductivity. We demonstrate the feasibility of measuring semiconductor samples using standard TDTR instrumentation, without the use of a metal transducer. A mathematical model accounting for non-zero laser penetration depth as well as both thermal and charge carrier effects is presented, and the ability of the model to describe and fit to experimental data for silicon and germanium samples is demonstrated. Though at this stage measurement uncertainties are larger than for traditional TDTR, we anticipate that the use of this technique will expand the range of samples that can be measured with existing TDTR setups.
Hole mobility behavior in Al-gradient polarization-induced p-type AlGaN grown on GaN template
Authors: Chen Chung-Chi , Huang Ting-Chun , Lin Yu-Wei , Lin Yu-Ren , Wu Ping-Hsiu , Liou Ping-Wei , Hsieh Hao-Yu , Huang Yang-Yi , Yang Shaobo , Wu Yuh-Renn , Yang C. C.
Published: January 2022

A series of samples with their AlGaN layers of decreasing Al contents along the c-axis are grown on GaN templates with molecular beam epitaxy for producing polarization-induced p-type behaviors. By fixing the Al-gradient rate at 0.15%/nm and AlGaN layer thickness at 100 nm while changing the central Al content in those samples, we study the dependence of hole mobility on the central Al content. As the central Al content increases, hole mobility decreases monotonically with two different decreasing slopes in the two Al-content ranges divided at ∼40%. Tensile strain relaxation is observed when the Al content is higher than ∼40%, resulting in the increase in overall polarization gradient and, hence, hole concentration. Although the variation of the alloy scattering strength of hole in AlGaN can support the smaller decreasing slope of hole mobility in the Al-content range of >40%, other factors, such as piezoelectric scattering and bound charge distribution, may need to be considered for a complete interpretation. Compared with Mg-doped p-type AlGaN of 25% in an Al content, the polarization-induced p-type AlGaN can provide us with a higher hole mobility level at about the same hole concentration.
MaxwellNet: Physics-driven deep neural network training based on Maxwell’s equations
Authors: Lim Joowon , Psaltis Demetri
Published: January 2022

Maxwell’s equations govern light propagation and its interaction with matter. Therefore, the solution of Maxwell’s equations using computational electromagnetic simulations plays a critical role in understanding light–matter interaction and designing optical elements. Such simulations are often time-consuming, and recent activities have been described to replace or supplement them with trained deep neural networks (DNNs). Such DNNs typically require extensive, computationally demanding simulations using conventional electromagnetic solvers to compose the training dataset. In this paper, we present a novel scheme to train a DNN that solves Maxwell’s equations speedily and accurately without relying on other computational electromagnetic solvers. Our approach is to train a DNN using the residual of Maxwell’s equations as the physics-driven loss function for a network that finds the electric field given the spatial distribution of the material property. We demonstrate it by training a single network that simultaneously finds multiple solutions of various aspheric micro-lenses. Furthermore, we exploit the speed of this network in a novel inverse design scheme to design a micro-lens that maximizes a desired merit function. We believe that our approach opens up a novel way for light simulation and optical design of photonic devices.
A setup for studies of photoelectron circular dichroism from chiral molecules in aqueous solution
Authors: Malerz Sebastian , Haak Henrik , Trinter Florian , Stephansen Anne B. , Kolbeck Claudia , Pohl Marvin , Hergenhahn Uwe , Meijer Gerard , Winter Bernd
Published: January 2022

We present a unique experimental design that enables the measurement of photoelectron circular dichroism (PECD) from chiral molecules in aqueous solution. The effect is revealed from the intensity difference of photoelectron emission into a backward-scattering angle relative to the photon propagation direction when ionizing with circularly polarized light of different helicity. This leads to asymmetries (normalized intensity differences) that depend on the handedness of the chiral sample and exceed the ones in conventional dichroic mechanisms by orders of magnitude. The asymmetry is largest for photon energies within several electron volts above the ionization threshold. A primary aim is to explore the effect of hydration on PECD. The modular and flexible design of our experimental setup EASI (Electronic structure from Aqueous Solutions and Interfaces) also allows for detection of more common photoelectron angular distributions, requiring distinctively different detection geometries and typically using linearly polarized light. A microjet is used for liquid-sample delivery. We describe EASI’s technical features and present two selected experimental results, one based on synchrotron-light measurements and the other performed in the laboratory, using monochromatized He-II α radiation. The former demonstrates the principal effectiveness of PECD detection, illustrated for prototypic gas-phase fenchone. We also discuss the first data from liquid fenchone. In the second example, we present valence photoelectron spectra from liquid water and NaI aqueous solution, here obtained from a planar-surface microjet (flatjet). This new development features a more favorable symmetry for angle-dependent photoelectron measurements.
The merging of bandgaps based on locally resonant plate with periodically attached stepped-frequency resonators
Authors: Li Qiaojiao , Sheng Meiping , Qin Qi , Han Yuying , Wang Shuai
Published: January 2022

Despite the development of more and more locally resonant (LR) structures of various resonant attachments, the application of LR structures in vibration attenuation is still limited by the widths of bandgaps. To achieve broadband vibration suppression at low frequencies, a LR plate with periodically attached stepped-frequency resonators (SFR) is proposed in this paper, where SFR refers to a group of local resonators with step-variable resonant frequencies. The extended plane wave expansion method is used to analyze the bandgap properties of the LR plate with SFR, and an exact series solution is used to analyze its vibration response. The merging of bandgaps based on SFR is revealed, and the parametric analysis shows that increasing the mass ratio or the damping of resonators is conducive to the merging effects, while increasing the frequency spacing makes the bandwidth of the merged bandgap to first increase and then decrease, as the bandgaps are gradually separated. Then, the optimal resonant frequencies of the SFR are obtained by maximizing the dominant vibration attenuation region. The numerical validation shows that the LR plate with SFR consisting of six resonators can provide broadband attenuation performance covering a frequency range from 190 to 450 Hz, which makes the LR structures more practical in vibration control.
Isothermal phase transition across phase boundary in (Pb0.95Ba0.05)ZrO3 ceramics
Authors: Li Feng , Liu Wei , Lou Xiaojie , Zhai Jiwei , Wang Chunchang
Published: January 2022

Paraelectric-ferroelectric-antiferroelectric (PE-FE-AFE) phase transitions induced by external stimulus (temperature, electric field, and hydrostatic pressure) usually produce exotic performances in functional ceramics. This Letter reports an isothermal phase transition in (Pb0.95Ba0.05)ZrO3 ceramics in the proximity of separated PE-FE and FE-AFE phase boundaries as extended waiting time. Through an isothermal process, PE (Pm3¯m)-to-FE (R3cH) and FE-to-AFE (Pbam) phase transformations occur within several minutes (with different transition degrees). This is in contrast to the wide recognition of ultrafast and time-independent ferroelectric transitions. In situ Raman spectra analysis unveils the sluggish growth of FE and AFE phases out of the corresponding parent matrix. Finally, the Landau theory analysis is proposed to explain the isothermal phase transition among PE-FE-AFE phases. This work will refresh the wisdom of phase transitions in functional ceramics.
First principles studies on infrared band structure and absorption of As/Sb lateral heterostructures
Authors: Liu Junsong , Tian Feng , Wang Dengkui , Fang Dan , Fang Xuan , Zhao Hongbin , Yang Xun , Li Weijie , Li Jinhua , Wang Xiaohua , Wei Zhipeng , Ma Xiaohui
Published: January 2022

Two-dimensional materials have been extensively investigated for fabricating high-performance visible optoelectronic devices. Considering the significance of mid-infrared band, narrow-band two-dimensional semiconductor materials have become the key point. In this work, we bring out two kinds of monolayer lateral heterostructures (LHSs) based on arsenic (As)/antimony (Sb) to realize the narrow band structure. The bandgap of LHS with an armchair interface is calculated to be 1.1 eV with an indirect band through the first principle, and the bandgap of LHS with a zigzag interface is 0.57 eV with a direct band. Their bandgaps are all shrunk by applying tensile or compressive strains. Furthermore, indirect-to-direct transitions appear in the armchair LHS when tensile strains are applied. Partial density-of-states and charge density distributions indicate that electron transmission from Sb atoms to As atoms may be the main factor for the reduction of the bandgap. In addition, the tensile strain extends the optical absorption to the infrared region. The As/Sb lateral heterostructures proposed in this paper are of great significance for infrared optoelectronic devices.
Ferroelectrics and photovoltaics in endohedral fullerenes-based van der Waals heterostructures
Authors: Li Jie , Wu Ruqian
Published: January 2022

Using the density functional theory calculations, we studied the ferroelectric, electronic, and optical properties of a series of bias-controllable endohedral fullerene molecules (TM@C28, TM = Ti-Ni). One important finding is that Cr@C28 has a large electric dipole moment and an appropriate bandgap (∼1.2 eV). By sandwiching Cr@C28 molecules between two graphene or transition metal dichalcogenide layers, the heterostructures may combine strong ferroelectricity and excellent optical properties. This paves the way for the development of two-dimensional van der Waals ferroelectric-photovoltaic materials.
Investigation of flow characteristics around a freely falling rigid sphere in a bounded fluid domain employing the shear stress transport k−ω improved delayed detached eddy simulation model
Authors: Pandey Deepak K. , Song Juhun , Lim Hee-Chang
Published: January 2022

The flow fields around a freely falling rigid sphere slamming onto a water surface in the bounded and unbounded domains were investigated using the shear stress transport k−ω improved delayed detached eddy simulation model. Based on the velocity of the sphere for all the domain cases, the Reynolds number was set equal to 106 in the investigation. The bounded domain was simulated by moving closer the wall of the water container from all around to the impacting location of rigid sphere and correlating it to the blockage ratio (BR). Two cases of bounded domains (BR = 45% and 70%) and a single case of the unbounded domain (BR = 0.01%) were studied. This study focused on analyzing the flow field when the sphere begins to impact the water until it is completely submerged. For BR = 70%, the mixing of air and water was observed in the wake region after making the complete submergence of the solid rigid sphere. In contrast, no such mixing was observed for other cases. The boundary layer reveals an increase in velocity and wall effect in the case of the bounded domain as compared to the unbounded domain. Higher magnitude of boundary layer thickness was achieved in the case of the unbounded domain as compared to the bounded domain. The Q and λ2 were used for vortex identification, and both the criteria were found to agree well with each other.
Misfit stress relaxation in wide bandgap semiconductor heterostructures with trigonal and hexagonal crystal structure
Authors: Smirnov A. M. , Kremleva A. V. , Sharofidinov Sh. Sh. , Romanov A. E.
Published: January 2022

In this work, we consider film/substrate semiconductor heterostructures with a hexagonal (wurtzite) and trigonal (corundum) crystal structure. We show that the differences between the stress level in the α-Ga2O3/α-Al2O3 heterostructure with the corundum crystal structure and the stress level in the GaN/AlN heterostructure with the wurtzite crystal structure do not exceed 50%. We study the effect of Al composition x and growth direction of the heterostructure on the critical film thickness for misfit dislocation formation in α-(AlxGa1−x)2O3/α-Al2O3 heterostructures. We provide a comparison between theoretical calculations of the critical film thickness and experimental data on the film thickness, at which the misfit dislocations were observed in α-(AlxGa1−x)2O3/α-Al2O3 heterostructures.
Computational investigation of drop behavior and breakup in peristaltic flow
Authors: Feigl Kathleen , Tanner Franz X.
Published: January 2022

The behavior of liquid drops in the retropulsive jet produced by a peristaltic wave is investigated computationally. The computational geometry consists of a tube which is closed at one end, with the peristaltic wave that deforms the boundary moving toward it. A modified solver with the capability to couple mesh deformation and adaptive mesh refinement around moving drops was developed and validated with experimental data, and good agreement was found. A parametric study was then performed to determine the effect of interfacial tension, viscosity ratio, relative occlusion, and initial drop position on the drop's behavior and breakup characteristics. In particular, breakup regimes on graphs of capillary number vs viscosity ratio were determined for each initial drop position and relative occlusion. It was found that these breakup regimes were bounded above and below, and an optimal capillary number for breakup was determined. The volume of the parent drop after breakup decreased linearly with capillary number for low capillary numbers and was independent of the viscosity ratio. For higher capillary numbers, this volume generally increased with the viscosity ratio. It was also found that a drop with lower interfacial tension reached the apex plane sooner than a drop with higher interfacial tension, but once there, took longer to pass through this plane and longer to breakup. The viscosity ratio had negligible influence on the drop transit times for viscosity ratios less than one, while the breakup time generally increased with the viscosity ratio.
Gate-tunable molybdenum disulfide/germanium heterostructure with ambipolar infrared photoresponse
Authors: Yang Maolong , You Jie , Wang Liming , Han Zhao , Zhang Yichi , Wang Bo , Zhang Ningning , Lin Dongdong , Liu Tao , Jiang Zuimin , Hu Huiyong
Published: January 2022

This paper proposes a molybdenum disulfide (MoS2)/Germanium (Ge) heterojunction device with a top gate composed of hexagonal boron nitride and graphene. First, the rectification direction of the device is reversed, and the rectification ratio is modulated from 0.09 to 7.3 by varying the gate voltage from −20 to 20 V. Optoelectronic characterization reveals that the device photoresponsivity and speed can improve by several orders of magnitude when graphene is used as the MoS2 contact electrode. There is an ambipolar photoresponse behavior in which the photocurrent polarity can be reversed depending on the wavelength of light and gate voltage applied. A conventional positive responsivity of 13.9 A/W is obtained with a 532 nm visible light. In contrast, the device responsivity changes from 33.7 A/W to −128 mA/W as the gate voltage decreases when a 1550 nm infrared light is used. This ambipolar infrared photocurrent is attributed to the competition between the bolometric effect in MoS2 and photocarrier effect in Ge. In addition, because it has opposite photoresponses at different wavelengths, this device has the potential to be used as a wavelength-distinguishing photodetector. These results offer a strategy for the development of two- and three-dimensional optoelectronic heterostructures.
Bi2Te3-based flexible thermoelectric generator for wearable electronics
Authors: Zou Qi , Shang Hongjing , Huang Daxing , Xie Bowei , Zhang Lin , Wang Kai , Dong Hao , Li Congmeng , Gu Hongwei , Ding Fazhu
Published: January 2022

The rapid development of the Internet of Things increases the demand for wearable devices. Compared with traditional chemical batteries, flexible thermoelectric technology contributes a solution for solving the power supply of wearable electronics. Here, we prepared n-type Bi2Te3 and p-type Bi0.5Sb1.5Te3 flexible thermoelectric films by the magnetron sputtering method, where the thermoelectric performance and their microstructures are systematically studied. The carrier concentration and mobility are optimized by adjusting the deposition temperature, eventually improving the thermoelectric performance and achieving the room-temperature power factors of 3.2 and 6.1 μW cm−1 K−2 for Bi2Te3 and Bi0.5Sb1.5Te3 films, respectively. Furthermore, after being bent 900 times with a radius of 5 mm, the resistance of these films barely increases, demonstrating the great potential for applications in wearable electronics. In order to further evaluate the practicability, these films are used to design a flexible thermoelectric generator, in which output performance improves with the increase in the temperature difference. The power density is up to ∼218.8 μW cm−2 at temperature differences of ∼41 K.
Quantum technologies in diamond enabled by laser processing
Authors: Giakoumaki A. N. , Coccia G. , Bharadwaj V. , Hadden J. P. , Bennett A. J. , Sotillo B. , Yoshizaki R. , Olivero P. , Jedrkiewicz O. , Ramponi R. , Pietralunga S. M. , Bollani M. , Bifone A. , Barclay P. E. , Kubanek A. , Eaton S. M.
Published: January 2022

Integrated photonic circuits promise to be foundational for applications in quantum information and sensing technologies, through their ability to confine and manipulate light. A key role in such technologies may be played by spin-active quantum emitters, which can be used to store quantum information or as sensitive probes of the local environment. A leading candidate is the negatively charged nitrogen vacancy (NV−) diamond color center, whose ground spin state can be optically read out, exhibiting long (≈1 ms) coherence times at room temperature. These properties have driven research toward the integration of photonic circuits in the bulk of diamond with the development of techniques allowing fabrication of optical waveguides. In particular, femtosecond laser writing has emerged as a powerful technique, capable of writing light guiding structures with 3D configurations as well as creating NV complexes. In this Perspective, the physical mechanisms behind laser fabrication in diamond will be reviewed. The properties of waveguides, single- and ensemble-NV centers, will be analyzed, together with the possibility to combine such structures in integrated photonic devices, which can find direct application in quantum information and sensing.
Experimental investigation on effects of injection distribution on combustion instability in a model rocket combustor
Authors: Guo Kangkang , Ni Lei , Ren Yongjie , Lin Wei , Tong Yiheng , Nie Wansheng
Published: January 2022

Self-excited combustion instabilities of transverse modes were experimentally investigated in a rectangular multi-injector model combustor, operating with the bipropellants O2/CH4. The propellants were injected through a linear array of five oxidizer-centered shear coaxial injectors into the combustor. High-amplitude limit cycles obtained in hot-fire tests were analyzed in detail. Different combustion instability modes, including first and second width modes, were observed in cases with three different injection distribution schemes. Hence, the injection distribution strongly determined the combustion dynamics. One insight can be gained that the stable combustion could be achieved by properly designing the propellants' injection distributions.
Study of adsorption of the SARS-CoV-2 virus spike protein by vibrational spectroscopy using terahertz metamaterials
Authors: Konnikova M.R. , Cherkasova O.P. , Geints T.A. , Dizer E.S. , Man’kova A.A. , Vasilievskii I.S. , Butylin A.A. , Kistenev Yu.V. , Tuchin V.V. , Shkurinov A.P.
Published: January 2022

Adhesion of the spike protein of the SARS-CoV-2 virus is studied by vibrational spectroscopy using terahertz metamaterials. The features of metastructure absorption upon the deposition of histidine, albumin, and the receptor-binding domain of the spike protein films are investigated. An original technique for quantitative assessment of the efficiency of virus adhesion on the metamaterial surfaces are proposed and experimentally tested.
Testing the adequacy of a simple theoretical model of dehydration optical clearing of collagen bundles: OCT measurements
Authors: Zyuryukina O.A. , Shvachkina M.E. , Kochubey V.I. , Sinichkin Yu.P. , Yakovlev D.A.
Published: January 2022

Using optical coherence tomography, the scattering coefficients of collagen bundles are estimated at different levels of tissue hydration. We test the validity of a simple theoretical model of dehydration changes in the optical characteristics of a collagen bundle, which is considered as a system of parallel cylinders that model the collagen fibrils forming the bundle. The characteristics of scattering by individual scatterers are calculated using the Mie theory. To take into account the cooperative effects caused by the close packing of the scatterers, use is made of the standard packing function for a system of identical cylinders. The theoretical model also relies on a certain empirical law of changes in the hydration level of fibrils with a change in the water content in the tissue, which predetermines changes in the diameter and refractive index of fibrils during dehydration and rehydration of the tissue. It is shown that the theoretical estimates obtained using this model are in good agreement with the experimental data, which makes it possible to consider this model as reliable.
YAG : R3+(R = Ce, Dy, Yb) nanophosphor-based luminescent fibre-optic sensors for temperature measurements in the range 20 – 500 °C
Authors: Evstropiev S.K. , Demidov V.V. , Bulyga D.V. , Sadovnichii R.V. , Pchelkin G.A. , Shurupov D.N. , Podrukhin Yu.F. , Matrosova A.S. , Nikonorov N.V. , Dukelskii K.V.
Published: January 2022

We report the development of a group of luminescent fibre-optic temperature sensors that use Ce3+-, Dy3+-, and Yb3+- doped yttrium aluminium garnet (YAG) nanophosphors as thermosensitive materials. The nanophosphors have been prepared in the form of powders with a crystallite size from 19 to 27 nm by a polymer – salt method and exhibit bright luminescence at 550 (YAG : Ce3+), 400, 480 (YAG : Dy3+), and 1030 nm (YAG : Yb3+). The sensor design includes a silica capillary, partially filled with a nanophosphor, and two large-aperture multimode optical fibres located in the capillary, which deliver excitation light and receive and transmit the photoluminescence signal. The photoluminescence signal amplitude of all the sensors decreases exponentially with increasing temperature, pointing to characteristic thermal quenching of photoluminescence and adequate operation of the devices up to 500 °C. The highest temperature sensitivity among the fibre-optic sensors is offered by the YAG : Ce3+nanophosphor-based devices.
Laser synthesis of nanocomposite hydrocarbon fuel and CARS diagnostics of its combustion flame
Authors: Barmina E.V. , Kobtsev V.D. , Kostritsa S.A. , Orlov S.N. , Smirnov V.V. , Zhilnikova M.I. , Uvarov O.V. , Shafeev G.A.
Published: January 2022

We report an analysis of diffusive combustion in oxygen of a composite fuel formed by the addition of aluminium nanoparticles (NPs) to isopropanol. The process of obtaining Al NPs consisted in laser fragmentation of initially large industrial NPs using radiation of a pulsed nanosecond neodymium laser. The size distribution of Al NPs was determined using a measuring disk centrifuge. The average nanoparticle size was 20 nm, which is confirmed by transmission electron microscopy data. A diagnostic system based on coherent anti-Stokes Raman scattering (CARS) was used to experimentally study the diffusive combustion of composite fuel. The temperature distributions were measured in two mutually orthogonal directions (along the flame and in the transverse direction) in pure isopropanol and in isopropanol with the addition of 0.15 wt % of Al nanoparticles.
Do you CBI what I see? The relationship between the Composite Burn Index and quantitative field measures of burn severity varies across gradients of forest structure
Authors: Saberi Saba J. , Agne Michelle C. , Harvey Brian J.
Published: January 2022

Burn severity in forests is commonly assessed in the field with visual ordinal estimates such as the Composite Burn Index (CBI). However, how CBI (a composite of several individual field measures) relates to independent quantitative measures of burn severity (e.g. fire-caused tree mortality, surface charring) has not been widely tested. Here, we use field data from 315 plots in 14 fires in the north-western USA to ask: (1) how CBI relates to eight independent field measures of burn severity; and (2) how these relationships vary across gradients of pre-fire forest structure. Overall, CBI corresponded well with most independent field measures, but some measures of extreme burn severity (e.g. deep charring on trees and snags) were not captured by CBI. Additionally, some measures of canopy burn severity corresponded to lower CBI values in forests with larger average tree size (diameter and height) – potentially from decoupling of surface and canopy fire effects in stands with larger, fire-resistant trees. Our findings suggest continued broad utility of CBI, while highlighting how the correspondence of aggregate plot-level CBI to different measures of burn severity can vary with forest conditions. We also suggest considerations for broadening CBI to account for more extreme levels of burn severity.
Conservation of magnetite biomineralization genes in all domains of life and implications for magnetic sensing
Authors: Bellinger M. Renee , Wei Jiandong , Hartmann Uwe , Cadiou Hervé , Winklhofer Michael , Banks Michael A.
Published: January 2022

Significance

We present a model of biogenic magnetite formation in eukaryotes and hypothesize this genetic mechanism is used by broad forms of life for geomagnetic sensory perception. Countering previous assertions that salmon olfactory tissues lack biogenic magnetite, we determine that it is present in the form of compact crystal clusters and show that a subset of genes differentially expressed in candidate magnetoreceptor cells, compared to nonmagnetic olfactory cells, are distant homologs to a core suite of genes utilized by magnetotactic bacteria for magnetite biomineralization. This same core gene suite is common to a broad array of eukaryotes and the Asgard clade archaea Lokiarchaeta. Findings have implications for revising our understanding of eukaryote magnetite biomineralization, sensory perception of magnetic fields, and eukaryogenesis.
Toward a new normal in foreign language classrooms
Authors: Liu Hsuan-Ying
Published: January 2022

Although Computer-Assisted Language Learning (CALL) is relied upon heavily in these disruptive times due to the COVID-19 pandemic, little is known about committed learners’ reactions to CALL as they actively voiced their questions and concerns during crisis-prompted remote learning. Employing a qualitative research method, findings reveal that their attitudes toward remote learning were ambivalent. While they viewed online tools as useful learning resources, they also expressed hesitation in adopting them. Meanwhile, they welcomed innovative ad hoc curriculum quickly developed by the instructor; however, the innovative curriculum was also viewed as less organized. These findings shed light on pedagogical implications for world language education in higher education and urge researchers to further investigate how remote language teaching and learning would affect committed students during the new normal times as foreign language enrollments continue to decline.
Linguistic injustice in academic publishing in English
Authors: Soler Josep
Published: January 2022

In recent years, an intense debate in English for research publication purposes (ERPP) has developed around the question of whether linguistic injustice exists or not in academic publishing in English. In this Perspectives piece, I wish to engage in this debate by first situating the terms in which it is being developed, and then pointing out some of its limitations. In doing that, I argue that the view of language that is currently held in the debate seems problematic, and that a more explicit attention to the socially stratified nature of academic publishing seems missing from the debate. Suggesting potential ways forward, I propose that it seems crucial to adopt a view of language that anchors it more firmly as a social phenomenon, inherently connected to its speakers and the socially situated and stratified position that they inhabit. Remembering this is important in order to remain aware of the fact that both linguistic and non-linguistic factors are at play in shaping the uneven nature of academic publishing in English.
Time pressure in translation
Authors: Weng Yu , Zheng Binghan , Dong Yanping
Published: January 2022

Translators may experience significant psychological and physiological responses to time pressure. This study examines such responses with the aim of identifying valid indicators of time pressure in written translation. Forty-five postgraduates participated in the study, translating three comparable English texts into Chinese under three time conditions (Short, Standard, and Free). A positive relation between time stringency and the arousal level detected by a set of self-reporting and biomarker measures was hypothesised. The hypothesis was corroborated by results derived from participants’ self-reporting on stress and anxiety, and the biomarkers of heart rate, blood pressure, and pupil dilation, but not by skin temperature, galvanic skin response (GSR), and heart rate variability (HRV). Thus, the measures that confirm the hypothesis are considered successful indicators of time pressure in translation. In addition, an inverted ‘U-shaped’ pattern was observed in the relation between time stringency and the arousal level indexed by GSR and HRV. These findings may facilitate research and training in translation and other cognitively demanding language-processing activities.
Understanding the long-term storage sink.
Authors: DeJong T. M.
Published: January 2022

Similar to short-term starch storage in the chloroplasts of the leaves that serves to buffer growth of organs from carbohydrate shortages due to diurnal patterns of photosynthesis related to daily patterns of light and darkness, trees also have long-term storage capacity to enable them to supply the minimal respiratory needs of tissues during the winter and resume growth in the spring when trees are still leafless. This long-term storage of carbohydrates and some minerals occurs primarily in the phloem and xylem tissue of the branches, trunk and roots. While active phloem tissue has higher concentrations of stored carbohydrates than xylem tissue, the mass of active xylem storage tissue is many times the mass of the active phloem tissue. Thus, xylem tissue comprises the largest storage compartment of temperate deciduous fruit trees. This chapter deals with understanding the long-term storage sink in fruit trees.
Consensus nomenclature for dyneins and associated assembly factors
Authors: Braschi Bryony , Omran Heymut , Witman George B. , Pazour Gregory J. , Pfister K. Kevin , Bruford Elspeth A. , King Stephen M.
Published: January 2022

Dyneins are highly complex, multicomponent, microtubule-based molecular motors. These enzymes are responsible for numerous motile behaviors in cytoplasm, mediate retrograde intraflagellar transport (IFT), and power ciliary and flagellar motility. Variants in multiple genes encoding dyneins, outer dynein arm (ODA) docking complex subunits, and cytoplasmic factors involved in axonemal dynein preassembly (DNAAFs) are associated with human ciliopathies and are of clinical interest. Therefore, clear communication within this field is particularly important. Standardizing gene nomenclature, and basing it on orthology where possible, facilitates discussion and genetic comparison across species. Here, we discuss how the human gene nomenclature for dyneins, ODA docking complex subunits, and DNAAFs has been updated to be more functionally informative and consistent with that of the unicellular green alga Chlamydomonas reinhardtii, a key model organism for studying dyneins and ciliary function. We also detail additional nomenclature updates for vertebrate-specific genes that encode dynein chains and other proteins involved in dynein complex assembly.
Flexible capacitive pressure sensors with micro-patterned porous dielectric layer for wearable electronics
Authors: Wang Jing , Li Longwei , Zhang Lanshuang , Zhang Panpan , Pu Xiong
Published: January 2022

Highly sensitive soft sensors play key roles in flexible electronics, which therefore have attracted much attention in recent years. Herein, we report a flexible capacitive pressure sensor with high sensitivity by using engineered micro-patterned porous polydimethylsiloxane (PDMS) dielectric layer through an environmental-friendly fabrication procedure. The porous structure is formed by evaporation of emulsified water droplets during PDMS curing process, while the micro-patterned structure is obtained via molding on sandpaper. Impressively, this structure renders the capacitive sensor with a high sensitivity up to 143.5 MPa−1 at the pressure range of 0.068 ∼ 150 kPa and excellent anti-fatigue performance over 20 000 cycles. Meanwhile, the sensor can distinguish different motions of the same person or different people doing the same action. Our work illustrates the promising application prospects of this flexible pressure sensor for the security field or human motion monitoring area.
Transition from spin glass to paramagnetism in the magnetic properties of PrAu2Si2
Authors: Li D X , Shimizu Y , Nakamura A , Sato Y J , Maurya A , Homma Y , Honda F , Aoki D
Published: January 2022

It is unexpected that a spin-glass (SG) transition, which generally occurs only in systems with some form of disorder, was observed in the ThCr2Si2-type compound PrAu2Si2 at a temperature of ∼3 K. This puzzling phenomenon was later explained based on a novel dynamic frustration model that does not involve static disorder. We present the results of re-verification of the reported SG behaviors by measuring the physical properties of three polycrystalline PrAu2Si2 samples annealed under different conditions. Indeed, in the sample annealed at 827 °C for one week, a SG transition does occur at a temperature of T
f ∼ 2.8 K as that reported previously in the literature. However, it is newly found that the SG effect is actually more pronounced in the as-cast sample, and almost completely disappears in the well-annealed (at 850 °C for four weeks) sample. The annealing effect observed in PrAu2Si2, that is, SG to paramagnetism transition is discussed by comparing with earlier results reported on the same system and other isomorphic compounds.
Analysis of local burnout in a sub-scale test coil for the 32 T magnet after spontaneous quenches during fast ramping
Authors: Hu X , Polyanskii A A , Abraimov D V , Gavrilin A V , Weijers H W , Kametani F , Jaroszynski J , Larbalestier D C
Published: January 2022

Abstract

Industrial production of REBa2Cu3O7-δ
(REBCO) coated conductors has made it possible to construct the 32 T magnet, the first successful all-superconducting user magnet to exceed 30 T, which now serves users as SCM4 (superconducting magnet) at the NHMFL. Here, we present an analysis of the damage that occurred in late-stage proof testing of the 32 T prototype coil after many essential facets of the design had been proven through more than 100 intentionally triggered quenches at fields up to 24 T. This prototype coil was then subjected to accelerated charge–discharge cycles at a rate 44 times faster than its design ramp rate in an attempt to address its fatigue tolerance. The extra hysteresis loss of the fast ramps led to heating of the end pancakes, which was induced after 55 fatigue cycles, three spontaneous quenches at progressively lower currents. Recognizing that the coil was damaged, the pancakes were then unwound and their REBCO tapes run through our continuous in-field transport I
c and remnant-field magnetization monitoring device, YateStar, which revealed three highly localized zones of low I
c in the end pancake that induced quench. Careful examination of these zones, especially the most intensely damaged one, revealed that the worst hot spot reached at least 779 °C during the quenches. Magneto-optical imaging showed that this damaged zone was about 5 mm in diameter and indeed the perpendicular damage length induced in neighboring turns by this localized quench heating was almost as great. Although there is much present concern about fatigue crack propagation from edge defects, we actually attribute this damage not to fatigue but to fluctuations in vortex pinning density due to imperfect BaZrO3 (BZO) nanorod growth that locally reduced the critical current I
c. These localized low-I
c regions then had to shed their excess current into the copper stabilizer, producing intense heating. We provide transmission and scanning electron microscopy evidence for local fluctuations of the BZO pinning structure and relate it to recent work that shows significant variations of 4 K, high field I
c values due to apparent production fluctuations of the growth conditions of the Zr-doped metal-organic chemical vapor deposition REBCO used for this test magnet.
Impact of the Coriolis interaction on the potential landscape evolution across the nuclide chart: Systematic total-Routhian-surface calculations
Authors: Zhang Hui-Hui , Wang Hua-Lei , Meng Hai-Yan , Liu Min-Liang , Ding Bing
Published: January 2022

Rotational structure properties along the yrast line for 766 observed even–even nuclei with Z ≥ 20 in the nuclide chart have been systematically studied by means of the approach of pairing-deformation self-consistent total Routhian surface calculations in three-dimensional deformation space (β
2, γ, β
4). Typical two-dimensional maps of the total nuclear energy are presented as functions of rotational frequency ℏ
ω. Various types of physical quantities (including nuclear shapes, aligned angular momenta, pairing gaps and excitation energies) are presented in the (Z, N) plane, indicating the overall characteristics. The ground-state deformations are compared with experimental data and other theoretical results. The present investigation shows that the Coriolis coupling may affect the overall properties systematically, for instance, enforcing regular drifts of the different deformation ‘islands’. We believe that the synthetic presentation will be helpful when planning high-spin experiments, especially in the data-scarce drip-line or superheavy regions. Moreover, such systematic and large-scale calculation and analysis can help overcoming and eliminating the bias among different theoretical models and be useful for checking and developing them.
Fiber-optic vector acoustic receiver based on adaptive holographic interferometer
Authors: Romashko R V , Storozhenko D V , Bezruk M N , Bobruyko D A , Kulchin Y N
Published: January 2022

A mobile scalar–vector acoustic receiver is proposed, experimentally implemented and investigated. The key components of the receiver are (a) the six-channel fiber-optic coil-type sensor configured as to detect three projections of acoustic intensity vector, (b) the six-channel optical phase demodulator based on six-channel adaptive holographic interferometer configured with use of dynamic holograms multiplexed in a photorefractive crystal of cadmium telluride and (c) the signals recording ADC-based system combined with software package for data processing. Field tests of the developed receiver applied for obtaining scalar and vector parameters of acoustic waves generated by a stationary and moving acoustic source in open air and water area are carried out. Experimental results show perceptiveness of use of the fiber-optical adaptive interferometry system for bearing of weak acoustic sources in real conditions.
High-fidelity quantum gates for OAM single qudits on quantum memory
Authors: Vashukevich E A , Bashmakova E N , Golubeva T Yu , Golubev Yu M
Published: January 2022

The application of high-dimensional quantum systems (qudits) in quantum computing and communications seems to be a promising avenue due to the possibility of increasing the amount of information encoded in one physical carrier. In this work, we propose a method for implementing single-qudit gates for qudits based on light modes with orbital angular momentum (OAM). Method for logical qudits encoding, which ensures the quasi-cyclicity of operations, is introduced. Based on the protocol for converting the OAM of light in the Raman quantum memory scheme (Vashukevich et al 2020 Phys. Rev. A 101 033830), we show that the considered gates provide an extremely high level of fidelity of single-qudit transformations. We also compare quantum gates’ properties for systems of different dimensions and find the optimal conditions for carrying out transformations in the protocol under consideration.
Linear seesaw model with a modular S
4 flavor symmetry *
Authors: Nomura Takaaki , Okada Hiroshi
Published: January 2022

We discuss a linear seesaw model with a field content as minimum as possible, introducing a modular

using gauged

symmetries. Owing to the rank two neutrino mass matrix, we obtain a vanishing neutrino mass eigenvalue, and only the normal mass hierarchy of neutrinos is favored via the modular

symmetry. In our numerical

analysis, we especially determine a relatively sharp prediction on the sum of neutrino masses to be approximately

meV, in addition to other predictions.
Fusion pilot plant performance and the role of a sustained high power density tokamak
Authors: Menard J.E. , Grierson B.A. , Brown T. , Rana C. , Zhai Y. , Poli F.M. , Maingi R. , Guttenfelder W. , Snyder P.B.
Published: January 2022

Recent U.S. fusion development strategy reports all recommend that the U.S. should pursue innovative science and technology to enable construction of a fusion pilot plant (FPP) that produces net electricity from fusion at low capital cost. Compact tokamaks have been proposed as a means of potentially reducing the capital cost of a FPP. However, compact steady-state tokamak FPPs face the challenge of integrating a high fraction of self-driven current with high core confinement, plasma pressure, and high divertor parallel heat flux. This integration is sufficiently challenging that a dedicated sustained-high-power-density (SHPD) tokamak facility is proposed by the U.S. community as the optimal way to close this integration gap. Performance projections for the steady-state tokamak FPP regime are presented and a preliminary SHPD device with substantial flexibility in lower aspect ratio (A = 2–2.5), shaping, and divertor configuration to narrow gaps to an FPP is described.