bluuebunny/crossref_metadata_2025 huggingface dataset:
A Bayesian approach to luminescent down-conversion
Authors: Löning M. , Lombez L. , Guillemoles J.-F. , Suchet D.
Published: January 2021

Photon conversion embodies a range of promising possibilities in pushing the theoretical Shockley–Queisser efficiency model of classical solar cells. Luminescent down-conversion, despite its potential, is held back in practical applications due to the difficulty of proper characterization in no small part because of concurrent luminescent downshifting events. Recent advances have demonstrated the opportunity provided by photon correlation measurement for down-conversion characterization. In this methodological work, we present a general method based on Bayesian probabilities for deriving auto-correlation functions analytically. This method is then applied to the five down-conversion mechanisms reported in the literature and successfully tested against numerical simulations. We show that the zero delay auto-correlation function can be the most direct way to demonstrate down-conversion and assess its efficiency. Our analysis offers additional useful tools for the design of characterization experiments and emphasizes some universal behavior valid for all reported conversion mechanisms.
Light-tunable 2D subband population in a GaN/AlGaN heterostructure
Authors: Solovyev V. V. , Schmult S. , Krückeberg L. , Großer A. , Mikolajick T. , Kukushkin I. V.
Published: January 2021

2D electron density tuning from 5.3×1012 cm−2 to 8.8×1012 cm−2 by UV illumination has been demonstrated for an ultra-pure GaN/Al0.25Ga0.75N heterojunction. A single subband is occupied in the dark with an electron density of 5.3×1012 cm−2, while in the illuminated sample with an electron density of 8.8×1012 cm−2, characteristic beating patterns appear in magnetotransport data due to the filling of the second quantized subband. Simultaneously, this distribution is unambiguously confirmed by Landau level splitting and intensity oscillations in photoluminescence spectra. The electron densities and quantum lifetimes in each individual subband have been extracted independently, and the intersubband energy spacing amounts to 82 meV. Surprisingly, the quantum scattering time for electrons residing in the second subband is increased compared to its ground state counterpart.
Correlation between geometric parametric instability sidebands in graded-index multimode fibers
Authors: Deng Zhixiang , Chen Yu , Liu Jun , Zhao Chujun , Fan Dianyuan
Published: January 2021

The spectral analysis of the light propagating in normally dispersive graded-index multimode fibers is performed under initial noisy conditions. Based on the obtained spectra with multiple simulations in the presence of noise, we investigate the correlation in energy between the well-separated spectral sidebands through both the scattergrams and the frequency-dependent energy correlation map and find that conjugate couples are highly correlated while cross-combinations exhibit a very poor degree of correlation. These results reveal that the geometric parametric instability processes associated with each sideband pair occur independently from each other, which can provide significant insights into the fundamental dynamical effect of the geometric parametric instability and facilitate the future implementation of high-efficiency photon pair sources with reduced Raman decorrelations.
Noise-induced complex oscillatory dynamics in the Zeldovich–Semenov model of a continuous stirred tank reactor
Authors: Ryashko Lev
Published: January 2021

Noise-induced variability of thermochemical processes in a continuous stirred tank reactor is studied on the basis of the Zeldovich–Semenov dynamical model. For the deterministic variant of this model, mono- and bistability parametric zones as well as local and global bifurcations are determined. Noise-induced transitions between coexisting attractors (equilibria and cycles) and stochastic excitement with spike oscillations are investigated by direct numerical simulation and the analytical approach based on the stochastic sensitivity technique. For the stochastic model, the phenomenon of coherence resonance is discovered and studied.
Diffraction-like stratified magnetic field in a device of circular rings
Authors: Contoyiannis Y. , Potirakis S. M. , Papadopoulos P. , Kampitakis M.
Published: January 2021

A device consisting of an array of coaxial, identical, circular rings behaves like a solenoid when the ratio of its radius and distance between two successive rings is higher than 1. As this ratio decreases, the device significantly deviates from the solenoid behavior. At the same time, a diffraction-like phenomenon for the magnetic field appears when currents of random direction flow through the rings. This phenomenon demonstrates critical behavior. Thus, an extension of the diffraction phenomenon can be done beyond the classical wave diffraction. A possible application of this device could be the diffraction of charged particle beams.
Temperature dependence of photoluminescence spectra from a suspended single-walled carbon nanotube with water adsorption layer
Authors: Saito Yuta , Tanaka Yuichiro , Yamaguchi Genta , Kato Takashi , Konabe Satoru , Chiashi Shohei , Homma Yoshikazu
Published: January 2021

On a single-walled carbon nanotube (SWCNT) surface, water forms a peculiar adsorption layer comprising two monolayers, and the physical properties of this adsorption layer remain unclear. We studied the changes that occurred in this water adsorption layer from room temperature down to 140 K using photoluminescence (PL) spectroscopy of suspended SWCNTs. The PL emission energy exhibited complex changes with temperature depending on the chirality of the SWCNTs. These changes were described quantitatively on the basis of changes in the bandgap, the dielectric constant of the adsorption layer, and the strain imposed by the adsorption layer. The results suggested that the adsorption layer might be a two-dimensional disordered solid rather than a liquid.
Femtosecond nonlinear refraction of 2D semi-metallic redox exfoliated ZrTe2 at 800 nm
Authors: Maldonado Melissa , da Silva Neto Manoel L. , Vianna Pilar G. , Ribeiro Henrique B. , de Araújo Cid B. , Matos Christiano J. S. de , Seixas Leandro , Jawaid Ali M. , Busch Robert , Ritter Allyson J. , Vaia Richard A. , Gomes Anderson S. L.
Published: January 2021

Zirconium telluride, a transition metal dichalcogenide, was synthesized by a redox exfoliated method to obtain a 2D monolayer semi-metal. After being characterized for compositional and optical analysis, its third-order nonlinear optical (NLO) properties were studied by the Z-scan technique in the femtosecond (100 fs) regime at 800 nm. Interestingly, in this spectro-temporal regime and in the intensity range exploited, the only third-order NLO effect observed was nonlinear refraction, giving rise to a positive value of the nonlinear refractive index coefficient, n2 = +(4.2 ± 0.3) × 10−16 cm2/W. Based on the calculated band structure and the excitation photon energies employed, the physical origin of the refractive nonlinearity is discussed.
A hybrid model for simulation of fluid–structure interaction in water entry problems
Authors: Moradi Hashem , Rahbar Ranji Ahmad , Haddadpour Hassan , Moghadas Hajar
Published: January 2021

A hydroelastic hybrid model is developed to simulate the fluid–structure interaction in water entry problems using the partitioned approach. The interactions between a flat plate and the water are modeled by a hydroelastic model using explicit and implicit couplings. Both couplings are unstable due to numerical instability associated with the fluid added mass. To overcome the instability, an extended Wagner’s model is combined with the hydroelastic model, and a hybrid model is developed. The extended Wagner’s model is the extension of the classical Wagner’s model that is used to estimate the fluid inertial, damping, and restoring forces of a flexible plate within the potential flow theory. The fluid flow is described by the unsteady Reynolds averaged Navier–Stokes equations in the hydroelastic model and hybrid model. The longitudinal bending of the plate is approximated by the strips in all models. The hybrid model is verified and validated by comparing the available computational and semi-analytical results of the vertical and oblique water entries for the plate with different boundary conditions. The results show that the hybrid model is stable, accurate, and simple to implement. This two-dimensional model can be generalized to the third dimension and applied for more complex structures.
Experimental study on the vertical motion of colliding gravity currents
Authors: Okon Samuel Ukpong , Zhong Qiang , He Zhiguo
Published: January 2021

Predicting the consequences of colliding gravity currents remains one of the most significant challenges in geophysical fluid dynamics. While the collision phenomenon has long been established through field observations, irregular natural occurrence and measurement limitations denied a comprehensive quantitative analysis of its dynamics. Herein, we experimentally studied colliding gravity currents to describe the collision dynamics and quantify essential parameters that are difficult to measure in nature. Visualization techniques and particle image velocimetry were deployed to monitor the flow evolution and obtain the flow field of the colliding gravity currents. Results revealed that as gravity currents propagated into proximity, vertical motions developed along the respective fronts’ leading edge and became enhanced as the currents merged at collision. Although both symmetric and asymmetric collisions initiated a significant vertical displacement of the mixed fluid, the lifting pattern was dependent on the ratio of reduced gravities of the colliding currents. The displaced fluids reached maximum vertical velocity at low height; however, the velocity reduced as the displaced fluids approached maximum heights. The maximum height attained by the displaced fluid was a significant fraction of the initial fluid depth in the lock, regardless of the reduced gravity ratio. This paper quantifies the vertical motion of the displaced fluid during the collision process, describes the relationship between relevant current parameters and the vertical motions, and provides valuable preliminary contributions toward improving the overall understanding of collision dynamics at the frontal boundary.
Effects of salt and gel network structures on purple membrane stacking in hydrogels immobilized with poly(vinyl alcohol)
Authors: Yokoyama Yasunori , Yano Shunsuke , Kurita Riku , Karasawa Morise , Tanaka Hikaru , Takahashi Hiroshi , Kikukawa Takashi , Sonoyama Masashi , Takenaka Koshi
Published: January 2021

The effects of a gel network structure on purple membrane (PM) spontaneous stacking are discussed, with particular emphasis on the relationship between the PM periodic pre-structures before gelation. Such peculiar intermembrane pre-structures with a periodic distance of ∼20 nm have recently been found to provide an important key to PM stacking, which is critical for the engineering applications of PM. Here, we investigated how the PM stacking differs depending on the gel network of a poly(vinyl alcohol) gel. On the basis of the results, we propose a plausible interplay between the PM periodic pre-structures and the type of gel network for PM stacking. The results indicate that a porous gel network, in addition to the PM periodic pre-structure in solutions, is necessary for PM stacking in immobilized gel samples.
Optical second-harmonic generation microscopy as a tool for ferroelastic domain wall exploration
Authors: Yokota Hiroko , Uesu Yoshiaki
Published: January 2021

Domain walls (DWs) of four typical ferroelastics, CaTiO3 (CTO), LaAlO3 (LAO), Pb3(PO4)2 (PPO), and BiVO4 (BVO), were observed by the second harmonic generation (SHG) microscopy, and the results were compared. The DWs of the examined ferroelastics are all polar. This fact does not depend on whether the crystal is an insulator (CTO, LAO, and PPO) or a semiconductor (BVO), on whether it has ferroelectric instability (CTO) or not (LAO, PPO, and BVO), or on the DW state, namely, whether the DW is crystallographically prominent or non-prominent. The symmetry of these DWs was determined from the SHG anisotropy, and it was clarified that they are a subgroup of the high temperature phase. In the cases of CTO and PPO, stress was applied to move the DW, and its polarity and symmetry were examined. The main characteristics did not change even when stress was applied. In all samples, uniform SHG was observed for each DW. This indicates that the DWs of the examined ferroelastics seem to be in a ferroelectric single domain state.
Physics of phonon-polaritons in amorphous materials
Authors: Casella Luigi , Baggioli Matteo , Mori Tatsuya , Zaccone Alessio
Published: January 2021

The nature of bosonic excitations in disordered materials has remained elusive due to the difficulties in defining key concepts such as quasi-particles in the presence of disorder. We report on an experimental observation of phonon-polaritons in glasses, including a prominent boson peak (BP), i.e., excess of THz modes over the Debye law. A theoretical framework based on the concept of diffusons is developed to describe the broadening linewidth of the polariton due to disorder-induced scattering. It is shown here for the first time that the BP frequency and the Ioffe–Regel (IR) crossover frequency of the polariton collapse onto the same power-law decay with the diffusivity of the bosonic excitation. This analysis dismisses the hypothesis of the BP being caused by a relic of the van Hove singularity. The presented framework establishes a new methodology to analyze bosonic excitations in amorphous media, well beyond the traditional case of acoustic phonons, and establishes the IR crossover as the fundamental physical mechanism behind the BP.
Reduced scaling formulation of CASPT2 analytical gradients using the supporting subspace method
Authors: Song Chenchen , Neaton Jeffrey B. , Martínez Todd J.
Published: January 2021

We present a reduced scaling and exact reformulation of state specific complete active space second-order perturbation (CASPT2) analytical gradients in terms of the MP2 and Fock derivatives using the supporting subspace method. This work follows naturally from the supporting subspace formulation of the CASPT2 energy in terms of the MP2 energy using dressed orbitals and Fock builds. For a given active space configuration, the terms corresponding to the MP2-gradient can be evaluated with O(N5) operations, while the rest of the calculations can be computed with O(N3) operations using Fock builds, Fock gradients, and linear algebra. When tensor-hyper-contraction is applied simultaneously, the computational cost can be further reduced to O(N4) for a fixed active space size. The new formulation enables efficient implementation of CASPT2 analytical gradients by leveraging the existing graphical processing unit (GPU)-based MP2 and Fock routines. We present benchmark results that demonstrate the accuracy and performance of the new method. Example applications of the new method in ab initio molecular dynamics simulation and constrained geometry optimization are given.
Nonlinear signal distortion corrections through quantum sensing
Authors: Chaves Kevin R. , Wu Xian , Rosen Yaniv J. , DuBois Jonathan L
Published: January 2021

Having accurate gate generation is essential for precise control of a quantum system. The generated gate usually suffers from linear and nonlinear distortion. Previous works have demonstrated how to use a qubit to correct linear frequency distortions but have not commented on how to handle nonlinear distortions. This is an important issue as we show that nonlinear amplitude distortions from the RF electronics can affect Rabi pulses by as much as 10%. We present work that demonstrates how a transmon qubit can be used as a highly sensitive cryogenic detector to characterize these nonlinear amplitude distortions. We show that a correction can drive these errors down to <1% over a 700 MHz range. This correction technique provides a method to minimize the effects of signal distortions and can be easily applied to broadband control pulses to produce higher fidelity arbitrary quantum gates.
Efficient timing jitter simulation for passively mode-locked semiconductor lasers
Authors: Meinecke Stefan , Lüdge Kathy
Published: January 2021

Efficient simulation of the timing jitter in passively mode-locking lasers is key to their numerical investigation and optimization. We introduce a method based on the pulse-period fluctuation auto-correlation function and compare it against established methods with respect to their estimate error. Potential improvements of the computational cost by about two orders of magnitude are reported. This advantage may facilitate larger parameter studies of passively mode-locked lasers on small-scale clusters or even desktop computers and, thereby, guide the target-oriented design of future lasers with ultra-low timing jitter.
Measurements of quantum dot level populations using an optical waveguide
Authors: Tsukanov A.V.
Published: January 2021

A scheme is proposed for measuring electron level populations in a semiconductor quantum dot embedded in a multimode waveguide. The photon transmittance of the waveguide under steady-state pumping is shown to depend on the presence of an electron in the ground state of the quantum dot. The influence of waveguide, quantum dot, and photon source parameters on the electron detection process is examined. It is shown that, even at a moderate mode Q-factor (104 to 105), the measurement contrast and signal-to-noise ratio are rather high (above 104). The feasibility of using the proposed method for probing the state of a charge qubit is discussed.
Prospects for using silicon nanoparticles fabricated by laser ablation in hyperthermia of tumours
Authors: Sokolovskaya O.I. , Zabotnov S.V. , Golovan L.A. , Kashkarov P.K. , Kurakina D.A. , Sergeeva E.A. , Kirillin M.Yu.
Published: January 2021

The efficiency of using silicon nanoparticles, produced by laser ablation of porous silicon in liquids, as agents for hyperthermia of tumours using laser radiation with wavelengths of 633 and 800 nm is evaluated. Using the optical parameters of the nanoparticles suspensions determined earlier by the spectrophotometry measurements, the heating of tumour tissue with embedded nanoparticles is numerically modelled. The heat transfer equation is solved by the finite element method which considers the volumetric distribution of the absorbed light power, calculated by the Monte Carlo technique, as a distributed heat source. The simulations performed indicate that embedding silicon nanoparticles with a concentration of up to 5 mg mL−1into a tumour allows its maximum temperature to be increased by 0.2–4 °C in comparison with heating the tumour without nanoparticles depending on the irradiation wavelength and intensity.
Interaction of laser radiation and complexes of gold nanoparticles linked with proteins
Authors: Zar’kov S.V. , Avetisyan Yu.A. , Yakunin A.N. , Meerovich I.G. , Fixler D. , Savitsky A.P. , Tuchin V.V.
Published: January 2021

The results of numerical simulation of the near-field distribution inside and in the vicinity of two types of gold nanoparticles (nanospheres and nanorods) intended for producing complexes of gold nanoparticles linked with proteins and exciting photosensitizers in the wavelength range of 532 – 770 nm are presented. Quantitative estimates of the field localisation (enhancement) are obtained depending on the type of gold nanoparticles and dimensional factors. The tendency of the red shift of the wavelength at which the maximum local field enhancement is achieved relative to the positions of the maxima of the absorption and scattering cross sections of nanoparticles and complexes is described.
ADP-ribose and analogues bound to the deMARylating macrodomain from the bat coronavirus HKU4
Authors: Hammond Robert G. , Schormann Norbert , McPherson Robert Lyle , Leung Anthony K. L. , Deivanayagam Champion C. S. , Johnson Margaret A.
Published: January 2021

Significance

Severe coronavirus (CoV) infections have been responsible for hundreds of deaths. Since the emergence of severely pathogenic CoVs, namely the severe acute respiratory syndrome (SARS) virus in 2003, the Middle East respiratory syndrome (MERS) virus in 2012, and the SARS-CoV-2 in 2019, no licensed vaccine or effective antiviral treatment has been developed. Bats are reservoir hosts for many human viruses, including SARS and MERS. The protein relationship between human betacoronaviruses and their bat-specific ancestors is still unknown. This work includes a detailed structure-function analysis of a bat viral macrodomain and provides key insights into features relevant in determining conserved protein functions. This information is vital to the design of macrodomain inhibitors and antiviral therapies.
Doping evolution of the Mott–Hubbard landscape in infinite-layer nickelates
Authors: Goodge Berit H. , Li Danfeng , Lee Kyuho , Osada Motoki , Wang Bai Yang , Sawatzky George A. , Hwang Harold Y. , Kourkoutis Lena F.
Published: January 2021

Significance

Copper-based (cuprate) oxides are not only the original but also one of the best-studied families of “high-temperature” superconductors. With nominally identical crystal structure and electron count, nickel-based (nickelate) compounds have been widely pursued for decades as a possible analog to the cuprates. The recent demonstration of superconductivity in nickelate thin films has provided an experimental platform to explore the possible connections between the copper- and nickel-based superconductors. Here, we perform highly localized spectroscopic measurements to reveal a number of key differences between the two systems, particularly with regard to the hybridization between the O and metal (Cu or Ni) orbitals.
Small-molecule inhibitors for the Prp8 intein as antifungal agents
Authors: Li Zhong , Tharappel Anil Mathew , Xu Jimin , Lang Yuekun , Green Cathleen M. , Zhang Jing , Lin Qishan , Chaturvedi Sudha , Zhou Jia , Belfort Marlene , Li Hongmin
Published: January 2021

Significance

Cryptococcus neoformans
is an opportunistic human pathogen, causing cryptococcal meningitis in immunocompromised individuals, with a mortality rate of more than 50%. We previously found that the Prp8 intein was a viable drug target for
C. neoformans
. In an effort to find new therapies, we developed screening assays and identified a small molecule and its fluoride derivative as potent Prp8 intein-splicing inhibitors. These inhibitors bind covalently to an intein active-site residue and inhibit protein splicing, leading to nonfunctional Prp8, which is essential for fungal growth. These molecules inhibited growth of
C. neoformans
and showed synergistic or additive effects with Food and Drug Administration-approved antimycotics. Overall, the identification of these intein-splicing inhibitors opens up prospects for a new class of antifungals.
Hepatitis B virus X protein recruits methyltransferases to affect cotranscriptional N6-methyladenosine modification of viral/host RNAs
Authors: Kim Geon-Woo , Siddiqui Aleem
Published: January 2021

Significance

N6-methyladenosine (m
6
A) modification occurs in cellular RNAs and viral transcripts and regulates the fate of cellular and viral RNAs. Hepatitis B virus (HBV) transcripts are m
6
A-methylated in the consensus DRACH motif in the epsilon stem–loop, and this modification differentially regulates the viral life cycle depending on the m
6
A position at the 5′- or 3′-epsilon stem–loop. Here, we report that HBV X (HBx) protein recruits cellular m
6
A machinery onto HBV minichromosome and host PTEN chromosomal locus to add m
6
A modification cotranscriptionally. Induced m
6
A modification of HBV RNAs and PTEN mRNA by HBx decreases their stability. This study identifies the mechanism by which a viral protein regulates m
6
A modification of RNA.
Immature HIV-1 assembles from Gag dimers leaving partial hexamers at lattice edges as potential substrates for proteolytic maturation
Authors: Tan Aaron , Pak Alexander J. , Morado Dustin R. , Voth Gregory A. , Briggs John A. G.
Published: January 2021

Significance

HIV-1 particle assembly is driven by the viral Gag protein, which oligomerizes into a hexameric array on the inner surface of the viral envelope, forming a truncated spherical lattice containing large and small gaps. Gag is then cut by the viral protease, disassembles, and rearranges to form the mature, infectious virus. Here, we present structures and molecular dynamics simulations of the edges of the immature Gag lattice. Our analysis shows that Gag dimers are the basic assembly unit of the HIV-1 particle, lattice edges are partial hexamers, and partial hexamers are prone to structural changes allowing protease to cut Gag. These findings provide insights into assembly of the immature virus, its structure, and how it disassembles during maturation.
Effects of a training programme aimed at improving the pro-environmental competency of school children (Efectos de un programa de entrenamiento en competencias proambientales dirigido a niños escolarizados)
Authors: Ramirez-Ordoñez María-Jesús , Herrera-Mendoza Ketty-Milena , Orozco-Acosta Erick
Published: January 2021

Bearing in mind the need to understand and analyse the psychological processes involved in pro-environmental behaviour, in order to mitigate the negative effects of the current global ecological crisis, the aim of the research presented here is to analyse the effects of a pro-environmental competency (PEC) training programme on Colombian children. To this end, a quasi-experimental design was applied to a non-probabilistic sample of 102 subjects, evenly distributed between the experimental and control groups ( Mage = 8.13; SDage = 0.496; 43.1% female and 56.9% male), applying the ECOPRO-N scale and structured quantitative observation to measure pro-environmental competency. The results showed an increase in the pro-environmental competency of the experimental group with respect to the control group, specifically in the dimensions Beliefs ( d = 0.75), Knowledge ( d = 0.91) and Motives ( d = 0.32), with the greatest effect observed in the Knowledge dimension. This verifies the effectiveness of the intervention programme in terms of fostering pro-environmental behaviours among Colombian children.
The effect of nanorod position on the plasmonic properties of the complex nanorod in nanohole arrays
Authors: Wang Yanfeng , Zhang Zhengjun , Zhao Yiping
Published: January 2021

By moving the nanorod (NR) from the middle toward the rim of the nanohole (NH), i.e. breaking the geometric symmetry, the extraordinary optical transmission (EOT) caused by the dipole coupling of the localized surface plasmon resonance of the NR and the NH can be tuned to redshift exponentially while maintaining the high transmission and overall dimension of the structural unit. This resonant wavelength shift depends strongly on the moving direction of the NR, i.e. whether it is along the long axis or short axis of the rod. Connecting the NR to the NH and increasing the lattice period can significantly redshift the EOT mode, allowing ultra-high transmission in the mid-infrared (MIR) region. The high local E-fields, enhanced propagating waves with a tunable visible-MIR resonance wavelength, make this structure suitable for the design of compact and integrated optical devices from the visible to the MIR wavelength range. In addition, Fano resonances are emerging due to the coupling and hybridization of different plasmonic modes, making the structure beneficial for high sensitivity measurement.
Scalar dark matter, neutrino mass and leptogenesis in a U(1)
B−L
model
Authors: Mishra Subhasmita , Singirala Shivaramakrishna , Sahoo Suchismita
Published: January 2021

We investigate the phenomenology of singlet scalar dark matter (DM) in a simple U(1)
B−L
gauge extension of the standard model, made anomaly-free with four exotic fermions. The enriched scalar sector and the new gauge boson Z′, associated with U(1) gauge extension, connect the dark sector to the visible sector. We compute relic density, consistent with Planck limit and a Z′ mediated DM-nucleon cross section, compatible with PandaX bound. The mass of Z′ and the corresponding gauge coupling are constrained from LEP-II and LHC dilepton searches. We also briefly scrutinize the tree-level neutrino mass with a dimension five operator. Furthermore, resonant leptogenesis phenomena is discussed with TeV-scale exotic fermions to produce the observed baryon asymmetry of the Universe. Further, we briefly explain the impact of flavor in leptogenesis and we also project the combined constraints on Yukawa, consistent with oscillation data and observed baryon asymmetry. Additionally, we restrict the new gauge parameters by using the existing data on branching ratios of rare B(τ) decay modes. We see that the constraints from the dark sector are much more stringent from the flavor sector.
Properties of the density of shear transformations in driven amorphous solids
Authors: Ferrero Ezequiel E , Jagla Eduardo A
Published: January 2021

The strain load Δγ that triggers consecutive avalanches is a key observable in the slow deformation of amorphous solids. Its temporally averaged value ⟨Δγ⟩ displays a non-trivial system-size dependence that constitutes one of the distinguishing features of the yielding transition. Details of this dependence are not yet fully understood. We address this problem by means of theoretical analysis and simulations of elastoplastic models for amorphous solids. An accurate determination of the size dependence of ⟨Δγ⟩ leads to a precise evaluation of the steady-state distribution of local distances to instability x. We find that the usually assumed form P(x) ∼ x

θ
(with θ being the so-called pseudo-gap exponent) is not accurate at low x and that in general P(x) tends to a system-size-dependent finite limit as x → 0. We work out the consequences of this finite-size dependence standing on exact results for random-walks and disclosing an alternative interpretation of the mechanical noise felt by a reference site. We test our predictions in two- and three-dimensional elastoplastic models, showing the crucial influence of the saturation of P(x) at small x on the size dependence of ⟨Δγ⟩ and related scalings.
Non-equilibrium charge transport in a conjugated polymer
Authors: Cheng Xiao , Zhao Hui , Xie Hang
Published: January 2021

To address the non-equilibrium transport mechanism in a conjugated polymer, we investigate the dynamics of the lattice deformation and the charge transport in a polymer chain coupled with the reservoirs by the time-dependent non-equilibrium Green’s function formulism. We find that the delocalized soliton lattice wave (SLW) forms in the polymer, rather than the well-known localized excitations such as polarons and solitons. The source reservoir drives an electron-like transient dynamic SLW while the drain reservoir drives the hole-like one. These transient SLWs propagate in opposite directions and then merge and relax to a steady SLW. These results are confirmed by our analytical derivation based on the continuum model. When the bias voltages are symmetric (μ
L = −μ
R), the dynamic SLW subsides to the stationary soliton lattice (SL). In the energy domain, the sandwich-structured non-full filled SL bands form in the original gap, which can provide the conduction channels. Especially, in the case of the symmetric bias voltages (μ
L = −μ
R), the SL band is half-filled. The transmission current is the major part of the total current and the rest minor part is the effective current induced by the charge density waves accompanied by the SLW.
The charge-density-wave signature on the superfluid density of cuprate superconductors
Authors: de Mello E V L
Published: January 2021

The superfluid density or superconducting (SC) carrier concentration n
sc of cuprates has been the subject of intense investigations but there is not any single theory capable to explain all the available data. Here we show that the behavior of n
sc in under and overdoped cuprates are a consequence of an SC interaction based on charge fluctuations in the incommensurate charge-density-waves (CDW) domains. We have shown that this interaction scales with the CDW amplitude or the pseudogap (PG) energy, yielding local SC amplitudes and Josephson currents. The average Josephson energy

E

J

is proportional to the phase stiffness or superfluid density ρ
sc ∝ n
sc. We find that n
sc(p) increases almost linearly with doping p in the underdoped region and in the charge abundant overdoped only a few fractions of the holes condense leading to two kinds of carriers, a recently confirmed feature. The calculations and the ρ
sc data uncover how the PG–CDW–SC intertwined orders operate to yield cuprates properties.
Possible observation of the signature of the bad metal phase and its crossover to a Fermi liquid in κ–(BEDT–TTF)2Cu(NCS)2 bulk and nanoparticles by Raman scattering
Authors: Revelli Beaumont M , Hemme P , Gallais Y , Sacuto A , Jacob K , Valade L , de Caro D , Faulmann C , Cazayous M
Published: January 2021

κ‐(BEDT‐TTF)2Cu(NCS)2 has been investigated by Raman scattering in both bulk and nanoparticle compounds. Phonon modes from 20 to 1600 cm−1 have been assigned. Focusing on the unexplored low frequency phonons, a plateau in frequencies is observed in the bulk phonons between 50 and 100 K and assigned to the signature of the bad metal phase. Nanoparticles of κ‐(BEDT‐TTF)2Cu(NCS)2 exhibit anomalies at 50 K associated to the crossover from a bad metal to a Fermi liquid whose origins are discussed.
Korean-specific biokinetic model for iodine in radiological protection
Authors: Kwon Tae-Eun , Chung Yoonsun , Jin Young Woo
Published: January 2021

The International Commission on Radiological Protection (ICRP) recently adopted a detailed biokinetic model for systemic iodine with reference transfer coefficients based on typical worldwide dietary intakes of stable iodine. The regional data provided demonstrate that the ICRP reference thyroidal biokinetics may differ substantially across regions with atypically low or high dietary intakes of stable iodine. Importantly, the design of the ICRP model facilitates modifications of reference thyroidal kinetics based on regional dietary iodine intake. The present study extended the ICRP model to the South Korean population, whose dietary iodine intake is much higher than the global mean. The following three transfer coefficients were selected as targets for Korean-specific values: thyroidal uptake rate (λ
1), hormonal secretion rate (λ
4) and leakage rate of thyroidal organic iodine as inorganic iodide (λ
5). The Korean-specific values for λ
1, λ
4 and λ
5 were determined to be 4.48, 0.0086 and 0.0171 d−1, respectively, to yield the measurements of thyroidal iodine and physiological status of Korean adults. The determined λ
1 and λ
5 values differed noticeably from the ICRP values, whereas the λ
4 value was comparable to that of the ICRP. Compared with the ICRP reference model, the Korean model, in which the Korean-specific transfer coefficients were adopted, predicted noticeably lower thyroidal uptake and faster decrease of thyroidal iodine. In addition, the predicted cumulative activities of radioiodine in the thyroid were substantially lower (40–80%) than those predicted by the ICRP model. The Korean model developed in this study demonstrates that the iodine biokinetics for Koreans (i.e. a population with a high iodine consumption) obviously differ from the prediction of the ICRP model. Hence, the Korean model may serve to improve the accuracy of thyroid dose estimation for Koreans and will lead to practical changes in matters concerned with radiological protection.
Study of local anodic oxidation regimes in MoSe2
Authors: Borodin Bogdan R , Benimetskiy Fedor A , Alekseev Prokhor A
Published: January 2021

Scanning probe microscopy is widely known not only as a well-established research method but also as a set of techniques enabling precise surface modification. One such technique is local anodic oxidation (LAO). In this study, we investigate the LAO of MoSe2 transferred on an Au/Si substrate, focusing specifically on the dependence of the height and diameter of oxidized dots on the applied voltage and time of exposure at various humidities. Depending on the humidity, two different oxidation regimes were identified. The first, at a relative humidity (RH) of 60%–65%, leads to in-plane isotropic oxidation. For this regime, we analyze the dependence of the size of oxidized dots on the oxidation parameters and modify the classical equation of oxidation kinetics to account for the properties of MoSe2 and its oxide. In this regime, patterns with a maximum spatial resolution of 10 nm were formed on the MoSe2 surface. The second is the in-plane anisotropic oxidation regime that arises at a RH of 40%–50%. In this regime, oxidation leads to the formation of triangles oxidized inside the zigzag edges. Based on the mutual orientation of zigzag and armchair directions in successive oxidized layers, the stacking type and phase of MoSe2 flakes were determined. These results allow LAO to be considered not only as an ultra-high-resolution nanolithography method, but also as a method for investigating the crystal structure of materials with strong intrinsic anisotropy, such as transition metal dichalcogenides.
The MEMOS-U code description of macroscopic melt dynamics in fusion devices
Authors: Thorén E , Ratynskaia S , Tolias P , Pitts R A
Published: January 2021

The MEMOS-U physics model, addressing macroscopic melt motion in large deformation and long displacement regimes, and its numerical schemes are presented. Discussion is centred on the shallow water application to the metallic melts induced by hot magnetized plasmas, where phase transitions and electromagnetic responses are pivotal. The physics of boundary conditions with their underlying assumptions are analysed and the sensitivity to experimental input uncertainties is emphasized. The JET transient tungsten melting experiment (Coenenet al2015Nucl. Fusion55023010) is simulated to illustrate the MEMOS-U predictive power and to highlight key aspects of tokamak melt dynamics.
High-power and broadband microwave detection with a quasi-vertical GaN Schottky barrier diode by novel post-mesa nitridation
Authors: Sun Yue , Kang Xuanwu , Deng Shixiong , Zheng Yingkui , Wei Ke , Xu Linwang , Wu Hao , Liu Xinyu
Published: January 2021

We report a high-performance GaN Schottky barrier diode (SBD) on a sapphire substrate with a novel post-mesa nitridation technique and its application in a high-power microwave detection circuit. The fabricated SBD achieved a very high forward current density of 9.19 kA cm−2 at 3 V, a low specific on-resistance (R
ON,sp) of 0.22 mΩ cm2 and breakdown voltage of 106 V. An extremely high output current of 400 mA was obtained when the detected power reached 38.4 dBm@3 GHz in pulsed-wave mode with a small anode diameter of 70 μm. Meanwhile, broadband detection at frequencies ranging from 1 to 6 GHz was achieved at 33 dBm in continuous-wave mode.
An autonomous switch based on a rotating magnet driven by magnetic launchers
Authors: Boisseau Sebastien , Tosoni Olivier , Delette Gerard , Alessandri Baptiste , Boucaud Matthieu , Bohnke Marc , Despesse Ghislain , Cellier Christophe , Rannou Fabien , Baeza Alexandre , Perrot Alexandre , Daccord Marcel , Cessot Stéphane , Leprince Jérome , Vulcano Bruno , Bossan Christian
Published: January 2021

This paper reports on an innovative electromagnetic energy harvester for autonomous switches relying on a rotating magnet driven by magnetic launchers, and combined with a ferromagnetic circuit and a coil to turn the variation of magnetic flux induced by the rotating magnet into electricity. The device is able to operate on forward and backward translation movements. The energy harvester has been modeled, optimized, manufactured, characterized and integrated into a mechanical actuation system to form a complete autonomous switch that will be commercially available. The experimental output energy reaches 1.235 mJ (350 µJ cm−3) which is among the highest output energies and energy densities reached on autonomous switches in the state of the art. The electromechanical conversion efficiency is 56%, which is excellent for an energy harvester, and obtained thanks to the topology chosen for the electromagnetic converter. The energy harvester is finally connected to a diode-bridge-capacitor circuit to supply the RF emission of the commands with a Zigbee Green Power® transmitter.
Screen-printed flexible negative temperature coefficient temperature sensor based on polyvinyl chloride/carbon black composites
Authors: Xiao Yao , Jiang Shuwen , Li Yanrong , Zhang Wanli
Published: January 2021

Flexible temperature sensors are needed for real‐time temperature monitoring in healthcare, disease diagnosis, and ambient environment detection. In this work, a flexible negative temperature coefficient (NTC) temperature sensor based on polyvinyl chloride/carbon black (PVC/CB) was screen printed onto a polyethylene terephthalate substrate. The prepared temperature sensor exhibited high sensitivity (−0.148% °C−1), excellent linearity (R
2 = 0.995), a fast response time (0.7 s), and good repeatability when used to measure temperatures between 18 °C and 44 °C. The tunneling effect was used to explain the NTC of the PVC/CB temperature sensor, and its temperature sensing mechanism was proposed. Additionally, the sensor was used to monitor human breathing rates and temperatures, demonstrating its potential for real‐time skin or environmental temperature monitoring.
Electro-interpenetration as tool for high strain trilayer conducting polymer actuator
Authors: Fannir Adelyne , Plesse Cédric , Nguyen Giao T M , Vidal Frédéric
Published: January 2021

Electrochemical actuators based on electronic conducting polymers can convert electrical energy into mechanical work. The amplitude of the electromechanical response is related on volumetric charge density of conducting polymer electrodes and strain-to-charge ratio, an empiric electromechanical coupling parameter. In this work we describe the elaboration of high performance trilayer bending actuators by the electro-interpenetration of a conducting polymer, i.e. poly(3,4-ethylenedioxythiophene) (PEDOT), within a host membrane. The host membrane is first elaborated as an interpenetrating polymer networks combining nitrile butadiene rubber network and poly(ethylene oxide) network. An oxidative chemical prepolymerization of EDOT allows turning the host membrane into conductive substrate suitable for subsequent electropolymerization. The electropolymerization of EDOT from the chemically polymerized layer allows controlled interpenetration of PEDOT underneath the surface. A significant increase of local concentration of PEDOT in the electrodes, compared to those obtained from oxidative polymerization lead to a significant increase of the charge density. The polymerization conditions do not have significant impact on sign and absolute value of strain-to-charge ratio, but it can be improved by the nature of the electrolyte. The combination of these two effects leads to an actuator with up to 15% of strain difference.
Effects of higher levels of qubits on control of qubit protected by a Josephson quantum filter
Authors: Masuda Shumpei , Koshino Kazuki
Published: January 2021

A Josephson quantum filter (JQF) protects a data qubit (DQ) from the radiative decay into transmission lines (TLs) in superconducting quantum computing architectures. A transmon, which is a weakly nonlinear harmonic oscillator rather than a pure two-level system, can play a role of a JQF or a DQ. However, in the previous study, a JQF and a DQ were modeled as two-level systems neglecting the effects of higher levels. We theoretically examine the effects of the higher levels of the JQF and the DQ on the control of the DQ. It is shown that the higher levels of the DQ cause the shift of the resonance frequency and the decrease of the maximum population of the first excited state of the DQ in the controls with a continuous wave (cw) field and a pulsed field, while the higher levels of the JQF do not. Moreover, we present optimal parameters of the pulsed field, which maximize the control efficiency.
Inertia-induced nucleation-like motility-induced phase separation
Authors: Su Jie , Jiang Huijun , Hou Zhonghuai
Published: January 2021

Motility-induced phase separation (MIPS) is of great importance and has been extensively researched in overdamped systems, nevertheless, what impacts inertia will bring on kinetics of MIPS is lack of investigation. Here, we find a nucleation-like MIPS instead of spinodal decomposition in the overdamped case, i.e. not only the phase transition changes from continuous to discontinuous, but also the formation of clusters does not exhibit any coarsening regime. This remarkable kinetics of MIPS stems from a competition between activity-induced accumulation of particles and inertia-induced suppression of clustering process. More interestingly, the discontinuity of MIPS still exists even when the ratio of particle mass to the friction coefficient reduces to be very small such as 10−4. Our findings emphasize the importance of inertia induced kinetics of MIPS, and may open a new perspective on understanding the nature of MIPS in active systems.
Exothermic impact on Eyring-Powell nanofluid flow through a heated surface embedded in porous medium with thermal radiation: a numerical study
Authors: Khan Mumtaz , Rasheed Amer
Published: January 2021

The foremost aim of our study is to discuss the unsteady 2D MHD Powell-Eyring flow produced by a flat stretching surface. An incompressible chemical reactive MHD Eyring- Powell fluid immersed in porous medium filled the convective heated stretched sheet with the appearance of nanoparticles. A thorough in- vestigation is performed to study impacts of exothermic, first order chemical reactions and thermal radiation on the fluid flow. This study also assesses the heat and mass boundary conditions. The model utilized for nanoliquid elaborates the influence of thermophoresis and Brownian motion. Moreover, an efficient finite difference method is used and a numerical solution is obtained for the resulting nonlinear PDEs with appro- priate boundary conditions. A detailed discussion regarding how the principal variables affects the flow and thermal fields, is carried out. It is also discussed that how the flow and heat transfer processes is affected by the various parameters of interest. In addition to all this, the physical quantities such as Nusselt number, drag coefficient and mass transfer are calculated keeping in view their significance in engineering.
Perfect photon absorption based on the optical parametric process*
Authors: Zhang Yang , Ma Yu-Bo , Li Xin-Ping , Guo Yu , Yu Chang-Shui
Published: January 2021

The perfect photon absorption is studied in a cavity quantum electrodynamics (CQED) system, in which an optical parameter amplifier (OPA) is coupled to the cavity mode. This makes it possible to control the optical phase to realize the perfect photon absorption. It is found that in the presence of one and two injected fields, the perfect photon absorption is present in these two cases and can be controlled by adjusting the parametric phase. Moreover, different from the previous predictions of perfect photon absorption in atomic CQED systems, the perfect photon absorption can be changed significantly by the relative phase. Our work provides a new platform to use the parametric processes to make an available way to control the behaviors of photons and to take advantage of the optical phase to achieve the perfect photon absorption.
Wave packet dynamics of nonlinear Gazeau-Klauder coherent states of a position-dependent mass system in a Coulomb-like potential
Authors: Blaise Migueu Faustin , Vubangsi Mercel , Tchoffo Martin , Cornelius Fai Lukong
Published: January 2021

A D = 1 position-dependent mass approach to constructing nonlinear quantum states for a modified Coulomb potential is used to generate Gazeau–Klauder coherent states. It appears that their energy eigenvalues are scaled down by the quantum number and the nonlinearity coefficient. We study the basic properties of these states, which are found to be undefined on the whole complex plane, and some details of their revival structure are discussed.