bluuebunny/crossref_metadata_2025_split huggingface dataset:
Schottky barrier modification of GaSSe/graphene heterojunctions based on density functional theory
Authors: Lv Lingling , Shen Yanqing , Ma Yanyan , Gao Xu , Liu Jiajia , Wu Shengyao , Wang Xinyu , Gong Dewei , Zhou Zhongxiang 
Published: January 2021

Abstract
Constructing van der Waals heterojunctions is an effective way to solve the defects of two-dimensional (2D) material properties. The crystal structure and electronic properties of 2D monolayer GaSSe have been studied using first-principles calculation. Based on density functional theory calculations, we designed two different GaSSe/graphene heterojunctions and computed their electrical and interfacial properties. The calculated results confirm that graphene and GaSSe can maintain the original band structure after compounding, and the interaction between the two layers shows a weak van der Waals effect. The energy band gap of graphene can be opened to 25 meV when the GaSSe/graphene heterojunctions are formed. Graphene can be used as an electrode, and electrons will flow from the graphene layer to the GaSSe channel. Moreover, the interlayer distance and the applied electric field can be adjusted to modulate the Schottky barrier height and the Schottky contact type (n-type and p-type) of GaSSe/graphene heterojunctions. The two different heterojunctions can achieve Schottky contact-type conversion at a layer spacing of 3.00 and 2.70 Å, respectively. The position of the Dirac point of GaSSe/graphene heterojunctions will move with the change of the applied electric field. The Dirac point gradually moves towards the semiconductor valence band as the forward electric field of the heterojunctions increases. In addition, the n-type contact formed at the interface of the GaSSe/graphene heterojunctions will be converted into an Ohmic contact when the reverse electric field is about 0.5 eV Å−1. All the theoretical results clarify the fundamental properties of GaSSe/graphene heterojunctions and predict that the GaSSe/graphene heterojunctions can be used to design high-performance field effect transistor devices.
Theoretical study of a water sensor based on a single upconversion microrod
Authors: Wang Jie , Guo Rongxiang , Qin Yuan , Hu Haofeng , Cheng Zhenzhou , Wang Liang , Liu Tiegen 
Published: January 2021

Abstract
Water sensing is of great importance in wide applications of biomedicine, precision agriculture, chemical industrial processes, and food inspection. As a promising probe to detect water molecules, lanthanide-doped upconversion nanoparticles have drawn rapidly increasing research interest with the merits of the high photostability, fast response, and highly distinguishable spectrum. However, the detection sensitivity of such a technique is usually moderate due to the weak response of the luminescence to variations of water concentrations. Here, we theoretically study a sensitive water sensor based on a single NaGdF4:Yb3+/Tm3+ upconversion microrod. By utilizing whispering-gallery-mode resonance around the cross-section of the microrod, an upconversion laser is generated which can be employed to improve the detection sensitivity by about an order of magnitude compared with the sensors based on upconversion nanoparticle luminescence. The sensor is expected to be used for achieving the high-stability, high-sensitivity, high-spatial-resolution, and real-time detection of water molecules.
The influence of a nickelic interlayer on spin transport efficiency at a YIG/Pt interface
Authors: Liu Min , Sha Rongxin , Wang Mengyi , Peng Yibo , Zhang Ziyang , Zou Ailiang , Xu Yuekui , Guo Fangzhun , Qiu Zhiyong 
Published: January 2021

Abstract
Interfacial spin transport efficiency was studied in a yttrium iron garnet (YIG)/Pt spin-pumping system with different nickelic interlayers. It was found that the magnitude of the spin-pumping signals is sensitive to the chemical composition and crystalline orientation of the nickelic interlayers. As shown by the results obtained, a 2 nm thick metallic Ni interlayer enhances the spin-pumping signal, making it several times larger than that found for a YIG/Pt control sample. The spin-pumping signal around room temperature was found to be enhanced (suppressed) by antiferromagnetic NiO interlayers with perfect [111] orientation (without perfect [111] orientation). Our results confirm that a nickelic interlayer is a possible choice for optimizing interfacial spin transport, which is important for the development of a highly effective spin-based device.
Research on the spin Hall effect of light for nonlinear multilayer dielectrics and its bistable and nonreciprocal features
Authors: Wang Pengxiang , Wang Qianyu , Peng Hongmei , Zhang Dan , Zhang Haifeng 
Published: January 2021

Abstract
In this paper, by utilizing the transfer matrix method, a structure composed of one-dimensional (1D) periodic multilayer dielectrics, InSb, and nonlinear material is proposed to investigate the behavior of the spin Hall effect of light (SHEL) and its nonreciprocity and bistable features. The results demonstrate that, as the light intensity increases, the reflection coefficients under both TM and TE waves have a bistable phenomenon, and the points of both horizontal and vertical displacements are consistent with the regions where reflection is close to 0. Furthermore, to make our study complete, the thicknesses of the nonlinear and InSb layers are adjusted to study the effects on the performance of SHEL, and it can be found that, with the escalation of the thicknesses of the nonlinear and InSb layers, all the points of displacements are shifting to the direction of the angle. Besides, all parameters demonstrate the phenomenon of nonreciprocity. This research supplies meaningful guidelines for some optical instruments, such as light intensity sensors.
Measurement of therapeutic 12C beam in a water phantom using CR-39
Authors: Yang Shiyan , Zhao Jingfang , Zhuo Weihai , Shen Hao , Chen Bo 
Published: January 2021

Abstract
The motivation for this study was to explore a new method to test the particle spatial distribution for a therapeutic carbon beam. CR-39 plastic nuclear track detectors were irradiated to a 276.5 MeV u−1 mono-energy carbon beam at the heavy ion facility in the Shanghai Proton and Heavy Ion Center. The spatial distribution of the primary carbon beam and secondary fragments in a water phantom were systematically analyzed both in the transverse direction (perpendicular to the projection direction of the primary beam) and at different depths in the longitudinal direction (along the projection direction of the primary beam) with measured tracks on the CR-39 detectors. Meanwhile, the theoretically spatial distribution and linear energy transfer (LET) spectra of the primary beam and secondary fragments were calculated using the Monte Carlo (MC) toolkit Geant4. The results showed that the CR-39 detectors are capable of providing high lateral resolution of carbon ion at different depths. In the range of the primary carbon beam, the beam width simulated with MC is in good agreement with that of experimental measurement. The track size registered in the CR-39 has a good correlation with the particle LET. These findings indicate that the CR-39 can be used for measuring both the particle flux and its spatial distribution of carbon ions.
A technique for measurement of a prism apex angle by optical angle sensors with a reference artefact
Authors: Shimizu Yuki , Ma Xu , Matsukuma Hiraku , Gao Wei 
Published: January 2021

Abstract
A new technique for measurement of the apex angle of a right-angle prism is proposed. A reference artefact is newly employed as the datum for angle measurement, and the apex angle of a target prism is measured by detecting its deviation from that of the reference artefact by using a pair of optical angle sensors. At first, the principle of the apex angle measurement with the reference artefact and the optical angle sensors are addressed. After that, an optical angle sensor capable of evaluating various sizes of right-angle prisms over a large measurement range is designed and developed. A two-dimensional position-sensitive detector is employed as the photodetector for the optical angle sensor so that a high resolution and a wide measurement range can be achieved simultaneously. To avoid the influence of the interference between a directly-reflected beam and an internally-reflected beam when measuring a face of a right-angle prism, the optical setup is designed to have a laser beam that is made incident to a measurement surface with an oblique incidence. After the design and development of the optical angle sensor, the measurement system has been developed and some basic experiments are carried out to evaluate the basic performance of the developed optical angle sensor. The feasibility of the proposed technique of the prism apex angle measurement is also demonstrated through experiments and theoretical measurement uncertainty analysis based on GUM.
Two-dimensional ScN with high carrier mobility and unexpected mechanical properties
Authors: Liang Dongmei , Jing Tao , Deng Mingsen , Cai Shaohong 
Published: January 2021

Abstract
Two-dimensional (2D) semiconductors with desirable bandgaps and high carrier mobility have great potential in electronic and optoelectronic applications. In the present work, 2D M-ScN, H-ScN, and O-ScN are predicted by the swarm-intelligent global structure search method. The low formation energies and high dynamical and thermal stabilities indicate the high feasibility of experimental synthesis of these ScN monolayers. The electronic structure calculations reveal that M-ScN and O-ScN are both direct bandgap semiconductors with the bandgaps of 1.39 and 2.14 eV, respectively, while H-ScN has a large indirect bandgap of 3.21 eV. In addition, both M-ScN and H-ScN exhibit ultra-high electron mobilities (3.09 × 104 cm2 V−1 s−1 and 1.22 × 104 cm2 V−1 s−1, respectively). More notably, O-ScN is found to be a promising 2D auxetic and ferroelastic material. The values of negative Possion’s ratios and reversible strain of this monolayer are predicted to be −0.27% and 15%, respectively.
Calculating the duration of various physical phenomena using basic mathematical tools
Authors: Kontomaris S V , Malamou A 
Published: January 2021

Abstract
A significant approach that should be followed by physics teachers at the secondary education level in order to enhance students’ understanding is to highlight the generality of the mathematical procedures that describe different physical phenomena. In this paper, the common procedure that is used to calculate the duration of various physical phenomena is presented. Examples from different scientific areas, from mechanics to circuit analysis and from nuclear physics to medicine are examined. In the presented examples, the magnitude of interest is always directly proportional to its rate of change. By ‘grouping’ physical phenomena that can be described using the same mathematical tools, the students’ interest is enhanced and their physics perception is increased towards a deep understanding of the scientific methodology.
Teaching optics as inquiry under lockdown: how we transformed a teaching-learning sequence from face-to-face to distance teaching
Authors: Carli Marta , Fontolan Maria Rosa , Pantano Ornella 
Published: January 2021

Abstract
We describe the design and implementation of a teaching-learning sequence that was started before the lockdown and was then transformed for distance teaching. A backward design approach was adopted in order to identify clear learning outcomes. The activities were outlined according to an inquiry-based learning paradigm, referring to research-based models. We discuss how these elements were relevant when redesigning the activities for distance teaching. In particular, we describe how we modified an ‘application experiment’ (measuring the thickness of a human hair) using a video-based activity, highlighting how this activity was designed in order to meet the original goals and outcomes. The results of the teacher’s assessment and the students’ self-evaluation suggest that the approach was meaningful and effective, and that the experience can provide useful hints also for teaching under regular conditions.
Nonlinear electric response of chiral topological superconductors
Authors: Lee Minchul , Lόpez Rosa 
Published: January 2021

Abstract
We investigate, in the non-equilibrium Keldysh frame, a topological resistor–capacitor (RC) circuit consisting of a quantum dot coupled to a Majorana edge mode formed around a chiral topological superconductor. We implement both the adiabatic approximation and the numerical exact calculations to find out the unique non-equilibrium features of the electric response of the dissipative Majorana channel. First, the dependence of the dissipation on the frequency Ω of the ac driving on the dot is found to be greatly different whether the time-dependent dot level crosses the Fermi level or not during the driving. In the latter case, the relaxation resistance R
q, the measure of the dissipation, obeys R
q ∝ Ω2 for small frequencies, and in the former case, R
q ∝ Ω−1/3 diverges as Ω → 0. In the former case, a universal scaling law for the dissipative part of the ac power is observed and attributed to the δ-peak in the dot density of states due to a uncoupled dot Majorana mode at the dot resonance condition. We compare the ac power, current, and the relaxation resistance between Majorana and trivial Dirac channels and clarify the Majorana nature in the dissipation.
Understanding charge transfer on the clinically used conical Utah electrode array: charge storage capacity, electrochemical impedance spectroscopy and effective electrode area
Authors: Harris Alexander R 
Published: January 2021

Abstract

Objective. The Utah electrode is used for pre/clinical studies on neural recording and stimulation. Anecdotal and empirical reports on their performance have been made, resulting in variable testing methods. An in depth investigation was performed to understand the electrochemical behaviour and charge transfer mechanisms occurring on these clinically important electrodes. The impact of electrode geometry and material on performance was determined. Approach. Platinum and iridium electrodes were assessed by cyclic voltammetry and electrochemical impedance spectroscopy. The effective electrode area was measured by reduction of Ru(NH3)6
3+. Main results. Pristine Utah electrodes have little to no oxide present and the surface roughness is less than the diffusion length of Ru(NH3)6
3+ during voltammetry, which was ∼30 µm. Pristine iridium electrodes pass charge through capacitance and oxide formation. Hydride and anion adsorption occurs on the platinum electrode. Anodic current oxidises both metal surfaces, altering the charge transfer mechanisms at the electrode-solution interface. Charge storage capacity depends on measurement technique and electrode structure, this simplified number ignores more detailed information on charge transfer mechanisms that can be obtained from cyclic voltammetry. Electrode oxidation increases pseudocapacitance, reducing impedance. Charge transfer was non-homogeneous, most likely due to the electrode geometry enhancing charge density at the electrode tip and base. Oxidation of the electrode surface enhanced charge transfer inhomogeneity. The effective electrode area could be measured by reduction of Ru(NH3)6
3+ and calculated with a finite cone geometry. Significance. Increasing electrode pseudocapacitance, demonstrated by metal oxidation, reduces impedance. Increasing electrode capacitance offers a potential route to reducing thermal noise and increasing signal-to-noise ratio of neural recording. The effective electrode area of conical electrodes can be measured. The charge density of the conical electrode was greater than expected compared to a planar disc electrode, indicating modification of electrode geometry can increase an electrodes safe charge injection capacity. in vivo electrochemical measurements often do not include sufficient details to understand the electrode behaviour. Electrode oxidation most likely accounts for a significant amount of variation in previously published Utah electrode impedance data.
Response of thermal and fast-ion transport to beam ion population, rotation and T
e/T
i in the DIII-D steady state hybrid scenario
Authors: Thome K.E. , Du X.D. , Grierson B.A. , Kramer G.J. , Petty C.C. , Holland C. , Knolker M. , McKee G.R. , McClenaghan J. , Pace D.C. , Rhodes T.L. , Smith S.P. , Sung C. , Turco F. , Van Zeeland M.A. , Zeng L. , Zhu Y.B. 
Published: January 2021

Abstract
The thermal and fast-ion transport properties of DIII-D steady-state hybrid discharges with normalized beta β
N ≳ 3 are studied at low injected torque and an increased electron to ion temperature ratio T
e/T
i. Linear stability analysis performed with the TGLF turbulent code indicates that a high-k mode is usually dominant at smaller radii, whereas a low-k mode is usually dominant at larger radii in these plasmas. A reduction in the net injected torque from 8.6 to 4.3 N-m leads to reduced E × B shear and hence, an enhanced turbulence that was observed on the Doppler backscattering diagnostic and was also computed with TGLF. As T
e/T
i in the core was increased from 0.57 to 0.66 by adding electron cyclotron current drive (ECCD) to these plasmas, higher levels of transport are observed with increased high-k modes indicated by TGLF. The fast-ion transport level varied over an order of magnitude in these discharges depending on whether Alfvén eigenmodes, fishbones, or no instabilities were observed. Hybrid plasmas with fishbones have decreased fast-ion transport, compared to plasmas with Alfvén eigenmodes, since they are resonant with a smaller portion of phase space and their resonance is farther from the wall. This reduction in fast-ion transport with ECCD mitigates the increase in turbulent transport, resulting in higher performance than expected during strong electron heating. Similarly, the lowest fast-ion transport was observed in the low torque plasma, which also led to better than expected performance at this torque value. The thermal and fast-ion transport changes observed as the torque/rotation and T
e/T
i are varied indicate possible methods for transferring this scenario to a reactor.
Infinite system of random walkers: winners and losers
Authors: Krapivsky P L 
Published: January 2021

Abstract
We study an infinite system of particles initially occupying a half-line y ⩽ 0 and undergoing random walks on the entire line. The right-most particle is called a leader. Surprisingly, every particle except the original leader may never achieve the leadership throughout the evolution. For the equidistant initial configuration, the kth particle attains the leadership with probability e−2
k
−1(ln  k)−1/2 when k ≫ 1. This decay law provides a quantitative measure of the correlation between earlier misfortune proportional to the label k and eternal failure. We also show that the winner defined as the first walker overtaking the initial leader has label k ≫ 1 with probability decaying as

exp

−

1

2

(

ln

k

)

2

.
Spatial coherence effects in second-harmonic generation of scalar light fields
Authors: Pesonen Henri , Halder Atri , Huusko Juha-Matti , Friberg Ari T , Setälä Tero , Turunen Jari 
Published: January 2021

Abstract
We consider the spectral spatial coherence characteristics of scalar light fields in second-harmonic generation in an optically non-linear medium. Specifically, we take the fundamental-frequency (incident) field to be a Gaussian Schell-model (GSM) beam with variable peak spectral density and different coherence properties. We show that with increasing intensity the overall degree of coherence of both the fundamental and the second-harmonic field in general decreases on passage through the non-linear medium. In addition, the spectral density distributions and the two-point degree of coherence may, for both beams, deviate significantly from those of the GSM, especially at high intensities. Propagation in the non-linear medium is numerically analyzed with the Runge–Kutta and the beam-propagation methods, of which the latter is found to be considerably faster. The results of this work provide means to synthesize, via non-linear material interaction, random optical beams with desired coherence characteristics.
Effect of multiwalled carbon nanotube diameter on mechanical behavior and fracture toughness of epoxy nanocomposites
Authors: Xu Ting , Qi Zehao , Tan Yefa , Tian Jin , Li Xiaotun 
Published: January 2021

Abstract
Epoxy nanocomposites reinforced by multiwalled carbon nanotubes (MWCNT) with different diameters were prepared. The effect of MWCNT diameter on mechanical and fracture properties of epoxy nanocomposites were investigated. The results show that the MWCNT diameter has an important influence on its dispersion performance. As the MWCNT diameter increases, the dispersion performance becomes better. The reinforcing effect of MWCNTs on epoxy resins (EP) is affected by the combination of factors including the diameter and the additive amount of MWCNTs as well as its dispersion. At low additive amount of MWCNTs (≤0.3 wt%), the reinforcing effect of MWCNTs with smaller diameter is better. However, as the additive amount of MWCNTs increases (≥0.5 wt%), the reinforcing effect of MWCNTs with larger diameters becomes more significant. MWCNTs with diameter of 25 nm (MWCNT-25) have the best reinforcing effect when the additive amount is 0.5 wt%, and the tensile strength and elastic modulus of the MWCNT-25/EP composites are increased by 11.5% and 8.3% than those of EP, respectively. The fracture toughness of the composites shows a tendency to increase first and then decrease with the increase of MWCNT diameter. The main reason of this tendency is that the main failure mode of MWCNTs gradually changes from fracture to pull-out with the increase of MWCNT diameter. The optimal MWCNT diameter is 25 nm, reaching the best toughening effect (KIC and GIC are increased by 38.8% and 80.9% than those of EP, respectively) at the additive amount of 0.7 wt%.
Effect of samarium on the high temperature tensile properties and fracture behaviors of Al–Zn–Mg–Cu–Zr alloy
Authors: Zhai Fenglong , Wang Liping , Gao Xin , Zhao Sicong , Feng Yicheng , Ma Tao , Fan Rui 
Published: January 2021

Abstract
The Al-6.7Zn-2.6Mg-2.0Cu-0.1Zr alloy is modified by Sm for the purpose of improving its mechanical properties at high temperatures. According to the results, the as-cast structure can be refined through 0.3% Sm modification treatment, and finer precipitates can be obtained after aging. In the meantime, with the addition of Sm, a new high melting point Al10Cu7Sm2 phase is formed, the initial decomposition temperature of the alloy is raised, and the thermal stability is enhanced. As indicated by the tensile test results at room temperature and high temperatures, the strength of the modified sample was improved compared with the unmodified alloy. According to fracture surface analysis, ductile fracture conforms to the fracture characteristic exhibited by the modified alloy at room temperature and high temperatures. The improvement on high temperature strength of the modified alloy is attributed largely to a combination of grain refinement, precipitation strengthening and heat resistant phase to grain boundary pinning.