bluuebunny/crossref_metadata_2025 huggingface dataset:
Multiscale simulations of the electronic structure of III-nitride quantum wells with varied indium content: Connecting atomistic and continuum-based models
Authors: Chaudhuri D. , O’Donovan M. , Streckenbach T. , Marquardt O. , Farrell P. , Patra S. K. , Koprucki T. , Schulz S.
Published: February 2021

Carrier localization effects in III-N heterostructures are often studied in the frame of modified continuum-based models utilizing a single-band effective mass approximation. However, there exists no comparison between the results of a modified continuum model and atomistic calculations on the same underlying disordered energy landscape. We present a theoretical framework that establishes a connection between atomistic tight-binding theory and continuum-based electronic structure models, here a single-band effective mass approximation, and provide such a comparison for the electronic structure of (In,Ga)N quantum wells. In our approach, in principle, the effective masses are the only adjustable parameters since the confinement energy landscape is directly obtained from tight-binding theory. We find that the electronic structure calculated within effective mass approximation and the tight-binding model differ noticeably. However, at least in terms of energy eigenvalues, an improved agreement between the two methods can be achieved by adjusting the band offsets in the continuum model, enabling, therefore, a recipe for constructing a modified continuum model that gives a reasonable approximation of the tight-binding energies. Carrier localization characteristics for energetically low lying, strongly localized states differ, however, significantly from those obtained using the tight-binding model. For energetically higher lying, more delocalized states, good agreement may be achieved. Therefore, the atomistically motivated continuum-based single-band effective mass model established provides a good, computationally efficient alternative to fully atomistic investigations, at least at when targeting questions related to higher temperatures and carrier densities in (In,Ga)N systems.
An extended nonlinear Schrödinger equation for water waves with linear shear flow, wind, and dissipation
Authors: Li Shaofeng , Qian Suhui , Chen Hui , Song Jinbao , Cao Anzhou
Published: February 2021

Based on potential flow theory, governing equations are developed for surface gravity waves affected by wind, dissipation, and a linear shear flow (LSF). The LSF is composed of a uniform flow and a shear flow with constant vorticity. Using the multiple-scale analysis method, a two-dimensional nonlinear Schrödinger equation (NLSE) describing the evolution of freak waves in water of finite depth is derived by solving the governing equations. The modulational instability (MI) of the NLSE is analyzed, and it is shown that uniform up-flow and positive vorticity require a lower angular frequency to sustain the MI than uniform down-flow and negative vorticity. Moreover, the low-frequency section requires stronger wind velocity to sustain the MI than the high-frequency section. In other words, young waves are more sensitive to the MI than old waves. In addition, the free surface elevation of freak waves as a function of time is examined for different uniform flows, vorticities, and wind forcing, and the results are compared with a measured freak-wave time series from the North Sea. It is found that the theory agrees with the observations. Furthermore, the LSF affects the height and steepness of freak waves, while wind forcing affects their symmetry. Hence, the MI, wave–current interactions, and wind–wave interactions may be responsible for generating freak waves in realistic ocean scenarios.
Tuning material properties of amorphous zinc oxynitride thin films by magnesium addition
Authors: Welk A. , Reinhardt A. , Herrfurth O. , Schultz T. , von Wenckstern H. , Koch N. , Grundmann M.
Published: February 2021

The amorphous n-type multi-cation and multi-anion compound zinc magnesium oxynitride was fabricated by reactive long-throw magnetron co-sputtering from a metallic zinc and a metallic magnesium target. We achieved magnesium cation compositions in the thin films between 1 at. % and 7.5 at. % by varying the magnesium target power (variable-power approach) and compared this approach to a continuous composition spread. Both approaches lead to a reduction in Zn2+, an addition of Mg2+ cations, and a correlated increase in the oxygen content. Both these methods have the same effect on the optoelectrical properties: The increased magnesium content leads to a systematic decrease in the free charge carrier concentration regime from 1019 cm−3 to 1015 cm−3, a decrease in Hall mobility from 54 cm2 V−1 s−1 to 9 cm2 V−1 s−1, and a spectral shift of the absorption edge from 1.3 eV to 1.7 eV. The amorphous phase of zinc magnesium oxynitride is maintained until MgO crystallites form at a magnesium content ≥3 at. %. The electrical properties of the zinc magnesium oxynitride thin films show excellent long-term stability for at least 12 months.
Beyond the static corrugation model: Dynamic surfaces with the embedded atom method
Authors: Smits B. , Somers M. F.
Published: February 2021

The D2 on Cu(111) system has for many years been one of the major benchmark systems for surface scientists. Generating surface configurations using the embedded atom method (EAM), we investigate the quality of the chemically accurate static corrugation model (SCM) for including surface temperature effects, with a focus on the random displacement approach to its distorted surface generation. With this EAM potential, we also treat the Cu(111) surface of our system fully dynamically and shine a further light on not only the quality of the SCM sudden approach but also the limited effect of energy exchange with the surface. Reaction and (in)elastic scattering probability curves, as well as simulated time-of-flight spectra, show good agreement with both earlier works and experimental results, with surface reactions showing a preference for surface atoms displaced away from the incoming molecule. The good agreement with the non-static surface model also further establishes the limited effect of energy exchange on not only the reaction but also on the elastic and inelastic scattering probabilities, even though some molecular translational energy is deposited into the surface.
Design of intrinsically disordered proteins that undergo phase transitions with lower critical solution temperatures
Authors: Zeng Xiangze , Liu Chengwen , Fossat Martin J. , Ren Pengyu , Chilkoti Ashutosh , Pappu Rohit V.
Published: February 2021

Many naturally occurring elastomers are intrinsically disordered proteins (IDPs) built up of repeating units, and they can demonstrate two types of thermoresponsive phase behavior. Systems characterized by lower critical solution temperatures (LCSTs) undergo phase separation above the LCST, whereas systems characterized by upper critical solution temperatures (UCSTs) undergo phase separation below the UCST. There is congruence between thermoresponsive coil–globule transitions and phase behavior, whereby the theta temperatures above or below which the IDPs transition from coils to globules serve as useful proxies for the LCST/UCST values. This implies that one can design sequences with desired values for the theta temperature with either increasing or decreasing radii of gyration above the theta temperature. Here, we show that the Monte Carlo simulations performed in the so-called intrinsic solvation (IS) limit version of the temperature dependent self-Assembly of Biomolecules Studied by an Implicit, Novel, and Tunable Hamiltonian (ABSINTH) implicit solvation model yield a useful heuristic for discriminating between sequences with known LCST and UCST phase behavior. Accordingly, we use this heuristic in a supervised approach, integrate it with a genetic algorithm, combine this with IS limit simulations, and demonstrate that novel sequences can be designed with LCST phase behavior. These calculations are aided by direct estimates of temperature dependent free energies of solvation for model compounds that are derived using the polarizable atomic multipole optimized energetics for biomolecular applications forcefield. To demonstrate the validity of our designs, we calculate coil–globule transition profiles using the full ABSINTH model and combine these with Gaussian cluster theory calculations to establish the LCST phase behavior of designed IDPs.
Thermal vibration of circular single-layered MoS2 predicted by the circular Mindlin plate model
Authors: Zhang Yiqing , Wang Lifeng
Published: February 2021

Thoroughly understanding the dynamic behavior of two-dimensional molybdenum disulfide (MoS2) is extremely important to the MoS2-based nanoelectromechanical device. In this paper, the circular Mindlin plate model (CMPM) is proposed to investigate the temperature-induced vibration of circular single-layered MoS2 (CSLMoS2). When the size of the CSLMoS2 is very small, the natural frequencies calculated by the CMPM are closer to the natural frequencies calculated by molecular dynamic (MD) simulations than those calculated by the circular Kirchhoff plate model (CKPM). The frequencies obtained by the CMPM are closer to the MD results than those obtained by the CKPM when in the higher-order frequencies. The root-mean-squared (rms) amplitude of CSLMoS2 is calculated by the CMPM, the CKPM, and MD simulations. The rms amplitude of CSLMoS2 calculated by the CMPM is much larger than that calculated by the CKPM. The comparison of the rms amplitude calculated by MD simulations shows that both CMPM and CKPM can roughly predict the temperature-induced vibrational behavior of CSLMoS2. However, the rms amplitude forecasted by the CMPM is more accurate than that calculated by the CKPM. The CMPM can forecast the thermal vibration of CSLMoS2 well.
A recipe for an optimal power law tailed walk
Authors: Sakiyama Tomoko
Published: February 2021

Lévy-like movements, which are an asymptotic power law tailed distribution with an upper cutoff, are known to represent an optimal search strategy in an unknown environment. Organisms seem to show a Lévy walk when μ ≈ 2.0. In the present study, I investigate how such a walk can emerge as a result of the decision making process of a single walker. In my proposed algorithm, a walker avoids a certain direction; this may be related to the emergence of a Lévy walk. Instead of remembering all visited positions, the walker in my algorithm uses and remembers only the direction from which it has come. Moreover, the walker sometimes reconsiders and alters the directions it avoids if it experiences some directional inconsistencies in a series of recent directional moves, i.e., the walker moves in a different direction from the previous one. My results show that a walker can demonstrate power law tailed movements over a long period with an optimal μ.
Ferroelectric polymers and their nanocomposites for dielectric energy storage applications
Authors: Jiang Yanda , Zhou Mengjun , Shen Zhonghui , Zhang Xin , Pan Hao , Lin Yuan-Hua
Published: February 2021

Dielectric capacitors deliver the highest power density and operating voltage among known energy storage devices that are integrable in modern electronic and electrical systems. Ferroelectric polymers are promising dielectric energy storage media for film capacitors due to their superiority in excellent dielectric properties, high breakdown strength, and flexibility. Polymer-based nanocomposites by incorporating high-dielectric-constant nanofillers into the ferroelectric polymer matrix exhibit great potential for superior energy storage performances. This Perspective focuses on the development and progress of high-energy-density ferroelectric polymers and their nanocomposites. First, approaches are proposed to tune the ferroelectric hysteresis for suppressed dielectric and energy losses in ferroelectric polymers, which is the premise to achieve high energy density and high efficiency. Second, the energy storage properties of ferroelectric nanocomposites greatly depend on multiple factors such as nanofiller features, polymer/filler interfaces, and spatial composite structures, and effective strategies enabling enhancements of the dielectric constant and breakdown strength in nanocomposites are discussed. In the last part, some existing challenges and future perspectives are proposed to develop high-energy-density ferroelectric polymer-based materials for energy storage applications.
Measuring correlated electron motion in atoms with the momentum-balance density
Authors: Todd Lucy G. , Hollett Joshua W.
Published: February 2021

Three new measures of relative electron motion are introduced: equimomentum, antimomentum, and momentum-balance. The equimomentum is the probability that two electrons have the exact same momentum, whereas the antimomentum is the probability that their momenta are the exact opposite. Momentum-balance (MB) is the difference between the equimomentum and antimomentum and, therefore, indicates if equal or opposite momentum is more probable in a system of electrons. The equimomentum, antimomentum, and MB densities are also introduced, which are the local contribution to each quantity. The MB and MB density of the extrapolated-full configuration interaction wave functions of atoms of the first three rows of the periodic table are analyzed, with a particular focus on contrasting the correlated motion of electrons with opposite-spin and parallel-spin. Coulomb correlation between opposite-spin electrons leads to a higher probability of equimomentum, whereas Fermi correlation between parallel-spin electrons leads to a higher probability of antimomentum. The local contribution to MB, given an electron is present, is a minimum at the nucleus and generally increases as the distance from the nucleus increases. There are also interesting similarities between the effects of Fermi correlation and Coulomb correlation (of opposite-spin electrons) on MB.
Refractive indices of MBE-grown AlxGa(1−x)As ternary alloys in the transparent wavelength region
Authors: Papatryfonos Konstantinos , Angelova Todora , Brimont Antoine , Reid Barry , Guldin Stefan , Smith Peter Raymond , Tang Mingchu , Li Keshuang , Seeds Alwyn J. , Liu Huiyun , Selviah David R.
Published: February 2021

A series of AlxGa(1−x)As ternary alloys were grown by molecular beam epitaxy (MBE) at the technologically relevant composition range, x < 0.45, and characterized using spectroscopic ellipsometry to provide accurate refractive index values in the wavelength region below the bandgap. Particular attention is given to O-band and C-band telecommunication wavelengths around 1.3 µm and 1.55 µm, as well as at 825 nm. MBE gave a very high accuracy for grown layer thicknesses, and the alloys’ precise compositions and bandgap values were confirmed using high-resolution x-ray diffraction and photoluminescence, to improve the refractive index model fitting accuracy. This work is the first systematic study for MBE-grown AlxGa(1−x)As across a wide spectral range. In addition, we employed a very rigorous measurement-fitting procedure, which we present in detail.
Highly transparent and conductive ITO substrates for near infrared applications
Authors: Maniyara Rinu Abraham , Graham Christina , Paulillo Bruno , Bi Yu , Chen Yu , Herranz Gervasi , Baker David E. , Mazumder Prantik , Konstantatos Gerasimos , Pruneri Valerio
Published: February 2021

Indium tin oxide (ITO) is the most widely used transparent conductor in applications such as light emitting diodes, liquid crystal devices, touch screens, and photovoltaic cells. So far, its use has mainly been limited to the visible range (380 nm–750 nm), as it reflects at longer wavelengths and, consequently, its transmission is low. Here, we introduce a simple technique, based on high temperature annealing, which can reduce reflection in the near-infrared range (750 nm–2400 nm). With an optimized set of parameters, we were able to modulate the ITO properties and achieve a high transmission, greater than 80% including substrate contribution, at telecommunication wavelengths (C-band, 1530 nm–1565 nm) while still maintaining high electrical conductivity (resistivity <1.9 × 10−4 Ω cm). By using the newly developed infrared ITO transparent conductor, we demonstrate quantum dot solar cells with 27.7% enhancement in external quantum efficiency at the first exciton peak (1650 nm), and liquid crystal switching devices with 25% enhancement in transmission, with respect to device counterparts incorporating commercially available ITO.
Resonance energy transfer mediated by a chiral molecule
Authors: Salam A.
Published: February 2021

The problem of resonant energy transfer (RET) between an electric dipole donor, D, and an electric dipole acceptor, A, mediated by a passive, chiral third-body, T, is considered within the framework of molecular quantum electrodynamics theory. To account for the optical activity of the mediator, magnetic dipole and electric quadrupole coupling terms are included in addition to the leading electric dipole interaction term. Fourth-order diagrammatic time-dependent perturbation theory is used to obtain the matrix element. It is found that the Fermi golden rule rate depends on pure multipole moment polarizabilities and susceptibilities of T, as well as on various mixed electric and magnetic multipole moment response functions. The handedness of T manifests through mixed electric–magnetic dipole and mixed electric dipole–quadrupole polarizabilities, which affect the rate and, respectively, require the use of fourth-rank and sixth-rank Cartesian tensor averages over T, yielding non-vanishing isotropic rate formulae applicable to a chiral fluid medium. Terms of a similar order of magnitude proportional to the product of electric dipole polarizability and either magnetic dipole susceptibility or electric quadrupole polarizability of T are also computed for oriented and freely tumbling molecules. Migration rates dependent upon the product of the pure electric dipole or magnetic dipole polarizability with the mixed electric–magnetic or electric dipole–quadrupole analogs, which require fourth- and fifth-rank Cartesian tensor averaging, vanish for randomly oriented systems. Asymptotically limiting rate expressions are also evaluated. Insight is gained into RET occurring in complex media.
Embedded quantum-error correction and controlled-phase gate for molecular spin qubits
Authors: Chiesa A. , Petiziol F. , Macaluso E. , Wimberger S. , Santini P. , Carretta S.
Published: February 2021

A scalable architecture for quantum computing requires logical units supporting quantum-error correction. In this respect, magnetic molecules are particularly promising, since they allow one to define logical qubits with embedded quantum-error correction by exploiting multiple energy levels of a single molecule. The single-object nature of this encoding is expected to facilitate the implementation of error correction procedures and logical operations. In this work, we make progress in this direction by showing how two-qubit gates between error-protected units can be realised, by means of easily implementable sequences of electro-magnetic pulses.
Sexually antagonistic coevolution between the sex chromosomes of
Drosophila melanogaster
Authors: Lund-Hansen Katrine K. , Olito Colin , Morrow Edward H. , Abbott Jessica K.
Published: February 2021

Significance

Sex chromosomes are not only involved in genetic sex determination—they are also important factors in sexual conflict and speciation. Using laboratory experiments and population genetic modeling, we show that the sex chromosomes of
Drosophila melanogaster
can coevolve antagonistically. We found that swapping sex chromosomes between five
D. melanogaster
populations increased male fitness, apparently at the cost of reduced offspring survival. After 25 generations, these fitness effects had disappeared, consistent with the resolution of conflict after disrupting antagonistically coevolved X- and Y-linked genes. Our population genetic models show that antagonistic coevolution between sex chromosomes is a biologically plausible explanation for our empirical findings. Together, our empirical and theoretical results provide support for a potential path to speciation through sexual conflict.
Heterogeneous Hadean crust with ambient mantle affinity recorded in detrital zircons of the Green Sandstone Bed, South Africa
Authors: Drabon Nadja , Byerly Benjamin L. , Byerly Gary R. , Wooden Joseph L. , Keller C. Brenhin , Lowe Donald R.
Published: February 2021

Significance

The nature of Earth’s earliest crust is enigmatic due to the lack of a rock record for most of Earth’s first ∼600 My, the Hadean Eon. Studies have thus turned to scarce sites where Hadean detrital zircons have been discovered. The geochemistry of Hadean detrital zircon from a newly discovered site in South Africa suggests that the parental melts formed from variably hydrous melting of crust derived from the ambient mantle and show little evidence for an origin in arc-like settings. These results suggest that crust derived from ambient mantle played an important role during crust formation in the Hadean.
Elastic-instability–enabled locomotion
Authors: Nagarkar Amit , Lee Won-Kyu , Preston Daniel J. , Nemitz Markus P. , Deng Nan-Nan , Whitesides George M. , Mahadevan L.
Published: February 2021

Significance

Soft structures and materials are easily susceptible to mechanical instabilities, which can be harnessed for function, such as controlled locomotion. Here, we show how a reversible conical buckling instability of a pneumatically actuated sheet leads to an amphibious morph-bot that can crawl on land or swim in water. Our approach enables the design of novel shape-changing robots and other bioinspired machines at multiple scales using simple constituent materials and power sources.
A de novo strategy to develop NIR precipitating fluorochrome for long-term in situ cell membrane bioimaging
Authors: Li Ke , Lyu Yifan , Huang Yan , Xu Shuai , Liu Hong-Wen , Chen Lanlan , Ren Tian-Bing , Xiong Mengyi , Huan Shuangyan , Yuan Lin , Zhang Xiao-Bing , Tan Weihong
Published: February 2021

Significance

Long-term in situ imaging of biomolecules on the cell membrane was significant for studying the physiological processes emitted from cell signaling and cell adhesion. Thus, to develop an efficient tool to realize in situ imaging membrane-associated biomolecules, we herein proposed a de novo strategy to construct an antidiffusion probe by integrating a fluorochrome (HYPQ) characterized by strong hydrophobicity and low lipophilicity, with an enzyme substrate. Then, benefiting from the antidiffusion property of the constructed probe HYPQG, long-term in situ imaging of membrane-associated enzyme GGT was successfully realized. This work may provide an efficient strategy for constructing universal antidiffusion fluorescent probes to realize long-term in situ bioimaging.
The Srs2 helicase dampens DNA damage checkpoint by recycling RPA from chromatin
Authors: Dhingra Nalini , Kuppa Sahiti , Wei Lei , Pokhrel Nilisha , Baburyan Silva , Meng Xiangzhou , Antony Edwin , Zhao Xiaolan
Published: February 2021

Significance

In this work, we elucidate a checkpoint dampening mechanism in yeast. Using complementary biochemical and genetic approaches, we show that the Srs2 DNA helicase removes one of the first DNA damage sensors and the associated checkpoint kinase from chromatin, thus preventing hyperactivation of the DNA damage response. We further show that this role of Srs2 is separable from its well-known function as an antirecombinase and mainly accounts for Srs2’s contribution to genotoxin resistance. Our findings also shed light into potential means to regulate the dynamic association of RPA with single-stranded DNA in other cellular contexts and stimulate studies of checkpoint dampening and RPA regulation in other organisms.
Identification of a nuclear receptor/coactivator developmental signaling pathway in the nematode parasite
Strongyloides stercoralis
Authors: Cheong Mi Cheong , Wang Zhu , Jaleta Tegegn G. , Li Xinshe , Lok James B. , Kliewer Steven A. , Mangelsdorf David J.
Published: February 2021

Significance

Understanding the molecular mechanisms controlling nematode parasite infection is important to developing new therapeutic strategies. The DAF-12 nuclear receptor signaling pathway in free-living nematodes regulates a process known as the dauer diapause. In nematode parasites, this signaling pathway is believed to govern the infectious stage. To investigate this hypothesis, we characterized the orthologous components of DAF-12 and a parasite-specific transcriptional coactivator in the potentially lethal parasite
Strongyloides stercoralis
. Using a CRISPR method developed specifically for
S. stercoralis
, we demonstrate that DAF-12 and its coactivator are required for both the entry into and exit from the infectious stage. These studies further highlight the potential of therapeutically targeting this pathway in
S. stercoralis
and other nematode parasites.
The male germline-specific protein MAPS is indispensable for pachynema progression and fertility
Authors: Li Miao , Zheng Jiahuan , Li Gaopeng , Lin Zexiong , Li Dongliang , Liu Dongteng , Feng Haiwei , Cao Dandan , Ng Ernest H. Y. , Li Raymond H. W. , Han Chunsheng , Yeung William S. B. , Chow Louise T. , Wang Hengbin , Liu Kui
Published: February 2021

Significance

During meiosis prophase I in mammals, a series of events occur, such as homologous recombination, DSB repair, crossover formation, XY body formation, and meiotic sex chromosome inactivation (MSCI). We report here that a male pachynema-specific (MAPS) protein is essential for prophase I progression in mouse spermatocytes.
Maps
knockout causes the demise of pachytene spermatocytes throughout early to mid- and late pachynema, resulting in male but not female infertility. Moreover, protein ubiquitination was dramatically increased in
Maps

−/−

pachytene spermatocytes, likely contributing to the dysregulated global gene expression, including failed MSCI. In summary, MAPS is an indispensable protein for male fertility.
Understanding the high temperature side of the hot ductility curve for steels
Authors: Mintz B. , Qaban A.
Published: February 2021

The study tests the validity of the tensile hot ductility test for assessing cracking during the straightening operation. Steels with a thin film of deformation induced ferrite (DIF) or fully austenitic when straightening were examined. In both cases dynamic recrystallisation (DRX) occurs at high temperatures. However, DRX is not possible on straightening, the grain size being too coarse and strains too low. When, DRX occurs, ductility is overestimated compared to the un-recrystallised condition on bending. For steels with DIF films if the depth of the trough is ≥40%RA (reduction of area) cracking is unlikely. However, for TWIP steels, the estimated RA for unrecrystallised ϒ can be much < 40% causing cracking even though measured ductility is well in excess.
Dynamic mechanical behaviour induced by adiabatic temperature rise of Fe–Mn–Al–C steel
Authors: Wang C. H. , Sun C. Y. , Qian L. Y. , Cai W. , Jiang J. , Xiao Y.
Published: February 2021

The dynamic mechanical behaviour induced by adiabatic temperature rise of Fe–Mn–Al–C twinning-induced plasticity steel was investigated via the dynamic tensile test and a dynamic constitutive model. The twinning kinetics and recovery factor, which are all rate- and temperature-dependent, were introduced to describe the stress–strain relationships. Verified by experimental flow stress and twin volume fraction, simulated results are in good agreement with experimental ones. Because of the more active twinning that contributing plasticity at a higher strain rate, the decreasing plasticity from dislocation slip induces a retardation of dislocation multiplication and is responsible for the low strain hardening rate. In the later stage, the adiabatic heating promotes dislocation annihilation by enhanced dynamic recovery, resulting in the negative rate-dependent hardening.
Four keys to unlock IgG
Authors: Nimmerjahn Falk , Ravetch Jeffrey V.
Published: February 2021

The identification of discrete subclasses within the immunoglobulin G (IgG) isotype by Grey and Kunkel (1964. J. Exp. Med.https://doi.org/10.1084/jem.120.2.253) provided the framework for our current understanding of differential IgG subclass activity in protective and self-reactive immune responses.
An experiment for observing quantum gravity phenomena using twin table-top 3D interferometers
Authors: Vermeulen S M , Aiello L , Ejlli A , Griffiths W L , James A L , Dooley K L , Grote H
Published: February 2021

Theories of quantum gravity based on the holographic principle predict the existence of quantum fluctuations of distance measurements that accumulate and exhibit correlations over macroscopic distances. This paper models an expected signal due to this phenomenology, and details the design and estimated sensitivity of co-located twin table-top 3D interferometers being built to measure or constrain it. The experiment is estimated to be sensitive to displacements

∼

1

0

−
19

m
/

H
z

in a frequency band between 1 and 250 MHz, surpassing previous experiments and enabling the possible observation of quantum gravity phenomena. The experiment will also be sensitive to MHz gravitational waves and various dark matter candidates.
An acoustoelectric-induced tailorable coupled resonator surface acoustic waveguide
Authors: Taleb F , Darbari S , Khelif A , Taleb H
Published: February 2021

Here, we introduce a tailorable coupled resonator surface acoustic waveguide (CRSAW), based on a linear defect of elliptical cylinders inside a phononic crystal of ZnO pillars on a Si substrate. The designed elliptical resonators allow the emergence of a minimally dispersive, monomode shear-guiding band inside the local resonance bandgap, owing to their partially broken structural symmetry in comparison with their previously reported counterparts such as pillars and hollow cylinders. Moreover, by introducing reconfigurable waveguide behavior, we benefit from the acoustoelectric-induced elasticity modulation of ZnO, which is a semiconducting piezoelectric material. Switching the conductivity of ZnO structures between two limiting low and high values (0.01 S m−1 and 100 S m−1), a considerable waveguide modulation at full width at half maximum (FWHM) (ΔFWHM = −21%) and guiding frequency (Δfd
= −2.81%) are achieved for the designed optimized elliptical cylinder CRSAW while maintaining an acceptable loss value. Benefiting from the proposed ZnO-based elliptical CRSAW, we have achieved simultaneous monomode and low-bandwidth surface acoustic waveguide behaviors, without involving significant fabrication complications. The designed structures open up new horizons toward the realization of promising building blocks for designing reconfigurable and miniaturized SAW RF-filters, demultiplexers, and Mach–Zehnder devices for wireless communications applications.
Filamentary superconductivity in wrinkled PtSe2
Authors: Yuan Yahua , Duan Yuxia , Wang Zhongwang , Sun Jian
Published: February 2021

Platinum diselenide (PtSe2) is a recently discovered Dirac semi-metal, which is theoretically predicted to possess a superconducting transition at an extremely low temperature T

c
of 2 mK. However, it has not yet to be experimentally reported. We observe a filamentary superconducting transition at 2.3 K in the wrinkled PtSe2 induced by rapid thermal treatment. Certain crystalline deformation or phase transition occurs locally in PtSe2 due to the inhomogeneous strain induced during the temperature cycle, where T

c
could be significantly enhanced. The possibility of forming degraded PtSe2 or any superconducting compounds at the electric contacts during the thermal treatment is carefully ruled out. We investigate the magnetic field dependence of the superconductivity transition, i.e. the upper critical fields, and find the superconductivity in accordance with the Bardeen–Cooper–Schrieffer theory.
The impact of surface-to-volume ratio on the plasma activated water characteristics and its anticancer effect
Authors: Liu Zhijie , Wang Sitao , Pang Bolun , Zhang Huaiyan , Gao Yuting , Xu Dehui , Kong Michael G
Published: February 2021

Plasma activated water (PAW), as a green and potential technology, plays a significant role in bio-medicine applications. Surface-to-volume ratio of treated liquid during the preparation of PAW seriously affects the PAW chemistry characteristics, and ultimately results in different biological effects. However, that how does the surface-to-volume ratio affect PAW characteristics and anticancer effect induced by PAW is unclear. In this work, the surface-to-volume ratio is regulated to investigate the dynamic variation of chemical characteristics and cell apoptosis. Results display physicochemical properties including pH, ORP, and liquid temperature are varied with nonlinear trend besides conductivity. While the levels of RONS containing NO2
−, NO3
−, H+ are changed with linear trend except H2O2 ONOO− and O
.

2
−. Furthermore, increasing surface-to-volume ratio could effectively accelerate cell apoptosis, enhance intracellular ROS concentration and strengthen anticancer effects. Thus, it is concluded that tuning surface to volume ratio can effectively enhance the reactive species flux into the liquid that leads to remarkable anticancer activity of PAW rather than the surface-to-volume ratio that is directly responsible for the enhanced impact on the cells. Additionally, the possible apoptosis mechanisms linked with RONS are also discussed. Clarifying the relationship between the surface-to-volume ratio and the PAW characteristics is beneficial to much insights into the chemistry nature of PAW and tailoring biological effect caused by PAW.
Even and odd crystal fields on Fe2+ ions, local lattice distortion parameters, electron-deformation interaction, and magnetoelectric coupling in FeCr2O4
Authors: Vasin K V , Eremin M V
Published: February 2021

Within the framework of the quantum mechanical approach, the available experimental data are analyzed to identify the electronic structure of the multiferroic FeCr2O4. The relative values of the key contributions to the parameters of even and odd crystal fields acting on the 3d electrons of the Fe2+ ion are determined. Data on local lattice distortions are systematized. The parameter of the electron-deformation interaction of the ground term Fe2+ (5
E) is determined considering lattice distortions, and the parameters of binding of the spins of Fe2+ and Cr3+ to the electric field are estimated. The calculation results are compared with the available experimental data on the magnetic and structural characteristics of FeCr2O4, the critical temperature of the transition to an orbitally ordered state, optical conductivity data, the Mössbauer effect study, and measurements of spontaneous electric polarization.
High-temperature stability and phase transformations of titanium carbide (Ti3C2T
x
) MXene
Authors: Wyatt Brian C , Nemani Srinivasa Kartik , Desai Krishay , Kaur Harpreet , Zhang Bowen , Anasori Babak
Published: February 2021

Two-dimensional (2D) transition metal carbides, nitrides, and carbonitrides, known as MXenes, are under increasing pressure to meet technological demands in high-temperature applications, as MXenes can be considered to be one of the few ultra-high temperature 2D materials. Although there are studies on the stability of their surface functionalities, there is currently a gap in the fundamental understanding of their phase stability and transformation of MXenes’ metal carbide core at high temperatures (>700 °C) in an inert environment. In this study, we conduct systematic annealing of Ti3C2T
x
MXene films in which we present the 2D MXene flake phase transformation to ordered vacancy superstructure of a bulk three-dimensional (3D) Ti2C and TiC
y
crystals at 700 °C ⩽ T ⩽ 1000 °C with subsequent transformation to disordered carbon vacancy cubic TiC
y
at higher temperatures (T > 1000 °C). We annealed Ti3C2T
x
MXene films made from the delaminated MXene single-flakes as well as the multi-layer MXene clay in a controlled environment through the use of in situ hot stage x-ray diffraction (XRD) paired with a 2D detector (XRD2) up to 1000 °C and ex situ annealing in a tube furnace and spark plasma sintering up to 1500 °C. Our XRD2 analysis paired with cross-sectional scanning electron microscope imaging indicated the resulting nano-sized lamellar and micron-sized cubic grain morphology of the 3D crystals depend on the starting Ti3C2T
x
form. While annealing the multi-layer clay Ti3C2T
x
MXene creates TiC
y
grains with cubic and irregular morphology, the grains of 3D Ti2C and TiC
y
formed by annealing Ti3C2T
x
MXene single-flake films keep MXenes’ lamellar morphology. The ultrathin lamellar nature of the 3D grains formed at temperatures >1000 °C can pave way for applications of MXenes as a stable carbide material 2D additive for high-temperature applications.
Non-Hermitian semi-Dirac semi-metals
Authors: Banerjee Ayan , Narayan Awadhesh
Published: February 2021

Recently, many novel and exotic phases have been proposed by considering the role of topology in non-Hermitian systems, and their emergent properties are of wide current interest. In this work we propose the non-Hermitian generalization of semi-Dirac semimetals, which feature a linear dispersion along one momentum direction and a quadratic one along the other. We study the topological phase transitions in such two-dimensional semi-Dirac semimetals in the presence of a particle gain-and-loss term. We show that such a non-Hermitian term creates exceptional points (EPs) originating out of each semi-Dirac point. We map out the topological phase diagram of our model, using winding number and vorticity as topological invariants of the system. By means of numerical and analytical calculations, we examine the nature of edge states for different types of semi-Dirac models and establish bulk-boundary correspondence and absence of the non-Hermitian skin effect, in one class. On the other hand, for other classes of semi-Dirac models with asymmetric hopping, we restore the non-Hermitian skin effect, an anomalous feature usually present in non-Hermitian topological systems.
Object detection algorithm based on feature enhancement
Authors: Zheng Qiumei , Wang Lulu , Wang Fenghua
Published: February 2021

Recently, many excellent algorithms have made great progress in object detection, but there are also problems in these algorithms’ performance on targets of different sizes, and in particular in small object detection. Aiming at the problem of insufficient feature representation by the feature extractor, in this paper we propose a lightweight algorithm to improve feature extraction. The algorithm includes three modules. First, considering that the shallow features in feature extraction contain much background noise, in this paper we design a multi-level feedback propagation model based on a Gaussian high-pass filter. The shallow layers are enhanced using the filter and then back-propagated to add the upper shallow layer features and obtain new shallow layer features. This process is performed on the newly generated shallow layer for n iterations, which is beneficial for enhancing targets in the foreground area and suppressing background noise. Second, we form a stacked dilated convolution module with different dilation rates to cover the entire deep feature layer densely, which enlarges the receptive field and enriches the contextual information. Finally, we build a multi-scale fusion module to fuse the above-mentioned enhanced shallow and deep features to obtain output features with powerful representational ability for detection tasks. In addition, the model is easily embedded into existing approaches to enhance their performance. We build the model on the VGG-16 and ResNet-50 backbones and successfully applied it on Darknet-19 and Darknet-53 to verify its effectiveness and stability. The experiments on the COCO dataset prove that the proposed algorithm outperforms the state-of-art methods, with a mean average precision improvement reaching 2% on average. The effect is remarkable on small targets and complex backgrounds. Furthermore, it does not affect the detection speed significantly, so real time detection requirements can still be met.
A graphene-coated silk-spandex fabric strain sensor for human movement monitoring and recognition
Authors: Song Xian , Liu Xiaoting , Peng Yuxin , Xu Zhen , Liu Wenming , Pang Kai , Wang Jianxiang , Zhong Liang , Yang Qiang , Meng Jun
Published: February 2021

Flexible and stretchable sensors are emerging and promising wearable devices for motion monitoring. Manufacturing a flexible and stretchable strain sensor with desirable electromechanical performance and excellent skin compatibility plays an essential role in building a smart wearable system. In this paper, a graphene-coated silk-spandex (GCSS) fabric strain sensor is prepared by reducing graphene oxide. The sensor functions as a result of conductive fiber extending and woven structure deforming. The conductive fabric can be stretched towards 60% with high sensitivity, and its performance remains constant after a 1000-cycle test. Based on its superior performance, the GCSS is successfully employed to detect full-range human movement and provide data for deep learning-based gesture recognition. This work offers a desirable method to fabricate low-cost strain sensors for industrial applications such as human movement detection and advanced information science.
A non-invasive reference-based method for imaging the cerebral metabolic rate of oxygen by PET/MR: theory and error analysis
Authors: Narciso Lucas , Ssali Tracy , Iida Hidehiro , St Lawrence Keith
Published: February 2021

Positron emission tomography (PET) remains the gold standard for quantitative imaging of the cerebral metabolic rate of oxygen (CMRO2); however, it is an invasive and complex procedure that requires accounting for recirculating [15O]H2O (RW) and the cerebral blood volume (CBV). This study presents a non-invasive reference-based technique for imaging CMRO2 that was developed for PET/magnetic resonance imaging (MRI) with the goal of simplifying the PET procedure while maintaining its ability to quantify metabolism. The approach is to use whole-brain (WB) measurements of oxygen extraction fraction (OEF) and cerebral blood flow (CBF) to calibrate [15O]O2-PET data, thereby avoiding the need for invasive arterial sampling. Here we present the theoretical framework, along with error analyses, sensitivity to PET noise and inaccuracies in input parameters, and initial assessment on PET data acquired from healthy participants. Simulations showed that neglecting RW and CBV corrections caused errors in CMRO2 of less than ±10% for changes in regional OEF of ±25%. These predictions were supported by applying the reference-based approach to PET data, which resulted in remarkably similar CMRO2 images to those generated by analyzing the same data using a modeling approach that incorporated the arterial input functions and corrected for CBV contributions. Significant correlations were observed between regional CMRO2 values from the two techniques (slope = 1.00 ± 0.04, R
2 > 0.98) with no significant differences found for integration times of 3 and 5 min. In summary, results demonstrate the feasibility of producing quantitative CMRO2 images by PET/MRI without the need for invasive blood sampling.
Frustrated double ionization of atoms in circularly polarized laser fields
Authors: Kang HuiPeng , Chen Shi , Chen Jing , Paulus Gerhard G
Published: February 2021

We theoretically study frustrated double ionization (FDI) of atoms subjected to intense circularly polarized laser pulses using a three-dimensional classical model. We find a ‘knee’ structure of FDI probability as a function of intensity, which is similar to the intensity dependence of nonsequential double ionization probability. The observation of FDI is more favourable when using targets with low ionization potentials and short driving laser wavelengths. This is attributed to the crucial role of recollision therein, which can be experimentally inferred from the photoelectron momentum distribution generated by FDI. This work provides novel physical insights into FDI dynamics with circular polarization.
Automatic Classification of NVST Short-exposure Data Based on Deep Learning
Authors: Li Qiang , Zheng Sheng , Huang Yao , Liu Dejian
Published: February 2021

The New Vacuum Solar Telescope is one of the most important solar telescopes in China. However, in the process of reconstructing high-resolution solar data, the data may be distorted by thin film interference fringes. In this paper, an automatic classification method based on deep learning is proposed to distinguish fringe-contained data and fringe-free data, employing the Adaptive Wavelet Transform to construct the sample data set while transfer learning is utilized to train the classification model. The experimental results show that classification accuracy of the proposed method can reach up to 99.3%. This proposed method can make the high-resolution reconstruction pipeline run automatically whether the solar data contains fringes or not.
Brain sources’ activity in resting state before a visuo-motor task
Authors: Miraglia Francesca , Vecchio Fabrizio , Alù Francesca , Orticoni Alessandro , Judica Elda , Cotelli Maria , Rossini Paolo Maria
Published: February 2021

Objective. In modern neuroscience, the underlying mechanisms of the elaboration and reaction to different kinds of stimuli of the brain hemispheres remain still very challenging to understand, together with the possibility to anticipate certain behaviors to improve the performance. Approach. The purpose of the present study was to investigate the brain rhythms characteristics of electroencephalographic (EEG) recordings and in particular, their interhemispheric differences in resting state condition before a visuo-motor task in a population of healthy adults. During the task, subjects were asked to react to a sequence of visual cues as quick as possible. The reaction times (RTs) to the task were measured, collected and correlated with the EEG signals recorded in a resting state condition immediately preceding the task. The EEG data were analyzed in the space of cortical sources of EEG rhythms by the computation of the global spectra power density (GSPD) in the left and in the right hemisphere, and of an index of brain laterality (L). Main results. The results showed a negative correlation between the RTs and the GSPD in the central areas in the left and in the right hemisphere in both eyes open (EO) and eyes closed (EC) conditions. A close to significant and negative correlation was found in the parietal areas. Furthermore, RTs negatively correlated with L in the central areas in EC condition. The results showed a negative correlation between the RTs and the GSPD in the central areas in the left and in the right hemisphere in both EO and EC conditions. Significance. The correlations between the brain activity before a task and the RTs to the task can represent an interesting tool for exploring the brain state characterization for the upcoming tasks performance.
Retraction: A Methodology for the Synthesis of E-Commerce (Journal of Physics: Conference Series
1230 012004)
Authors: Amri Imti Tsalil , Yamalia Ikke , Rico  , Rohayani Hetty , Lestari Dewi
Published: February 2021

This article has been retracted by IOP Publishing on 18 February 2021 in light of clear evidence that it was computer generated. IOP Publishing is investigating why this was not identified during the submission and peer review process by the conference. As a member of the Committee for Publication Ethics (COPE) this has been investigated in accordance with COPE guidelines and it was agreed the article should be retracted.

Retraction published: 18 February 2021