bluuebunny/crossref_metadata_2025 huggingface dataset:
Simultaneous continuous-variable quantum key distribution and classical optical communication over a shared infrastructure
Authors: Xu Yuehan , Wang Tao , Li Lang , Zhao Huanxi , Huang Peng , Zeng Guihua
Published: October 2023

Integrating quantum key distribution (QKD) and classical optical communication for large-scale applications presents a significant challenge due to high cost and complexity. In this paper, we experimentally demonstrate the feasibility of simultaneous continuous-variable QKD (CV-QKD) and classical optical communication over a shared infrastructure. Through high-linearity modulators and detectors, we validated classical quadrature phase shift keying communication and CV-QKD protocol on a single platform by time-division multiplexing technology. Experimental results show that the classical communication achieved a bit rate of 200 Mbits/s, and the CV-QKD protocol achieved a secret key rate of 1.12 Mbits/s at 6 dB channel attenuation. This work reveals the feasibility of using a shared optical module to realize classical and quantum communication, leading to simplified integrating QKD and classical communication infrastructure.
Atomistic origin of kinetics in hydrated aluminosilicate gels upon precipitation
Authors: Zhao Cheng , Yu Jiahui , Chen Xuyong , Wu Qiaoyun , Zhou Wei , Bauchy Mathieu
Published: October 2023

Calcium–alumino–silicate–hydrate (CaO–Al2O3–SiO2–H2O, or C–A–S–H) gel, which is the binding phase of cement-based materials, greatly influences concrete mechanical properties and durability. However, the atomic-scale kinetics of the aluminosilicate network condensation remains puzzling. Here, based on reactive molecular dynamics simulations of C–A–S–H systems formation with varying Al/Ca molar ratios, we study the kinetic mechanism of the hydrated aluminosilicate gels upon precipitation. We show that the condensation activation energy decreases with the Al/Ca molar ratio, which suggests that the concentration of the Al polytopes has a great effect on controlling the kinetics of the gelation reaction. Significantly, we demonstrate that 5-fold Al atoms are mainly forming at high Al/Ca molar ratios since there are insufficient hydrogen cations or extra calcium cations to compensate the negatively charged Al polytopes at high Al/Ca molar ratios during accelerated aging.
60 years of the Kaye–Bernstein, Kearsley, Zapas rheological constitutive law for polymers
Authors: Mitsoulis Evan , Hatzikiriakos Savvas G.
Published: October 2023

The K–BKZ (Kaye–Bernstein, Kearsley, Zapas) rheological constitutive model is now 60 years old. The paper reviews the connections of the model and its variants with continuum mechanics and experimental evidence in polymer melt flow, presenting an up-to-date recap of research and major findings in the open literature. In the Introduction, an historical perspective is given on developments in the last 60 years of the K–BKZ model. Then, a section on mathematical modeling of polymer flows follows, including the governing equations of flow, the rheological constitutive equations (with emphasis on the viscoelastic integral constitutive equations of the K–BKZ type), dimensionless numbers controlling the flow, and relevant boundary conditions. The “Method of Solution” section reviews the major developments of numerical techniques for particle tracking and integral evaluation for the viscoelastic stresses. Finally, selected examples of successful application of the K–BKZ model in polymer flows are presented including considerations of wall slip and non-isothermal flows.
Spherical densities and potentials in exactly solvable model molecules
Authors: Nagy Á.
Published: October 2023

A recently initiated variant of density functional theory utilizes a set of spherically symmetric densities instead of the density. The exact functionals are unknown in the new theory akin to the standard density functional theory. In order to test approximate functionals exactly solvable models are introduced. A harmonic molecular ion, the analogue to the hydrogen molecule ion and a harmonic two-electron molecule showing analogy to the hydrogen molecule are proposed. It has been found that the wave function and the density can be given analytically. The exact spherical densities and the effective potentials of the Euler equations also have analytical form. It has been shown that the models can be easily extended to several “nuclei.”
Practical efficiency limit of laser power converters based on lead halide perovskite
Authors: Shen Chengxia , Ling Xufeng , Li Yanshuang , Chen Shijian , Deng Yehao
Published: October 2023

An ideal laser power converter (LPC) has a power conversion efficiency (PCE) limit of 100%; however, in a real device, additional losses degrade the PCE limit appreciably. We developed an approach to estimate the PCE of perovskite LPCs based on the state-of-the-art perovskite solar cells with a variety of losses. The practical PCE limit is found to be 60.2% under a 785 nm laser with power density of 50 mW/cm2, which result is corroborated by our experimentally measured PCE of 58.6%. Despite a comparable PCE to that of GaAs LPCs, the power output of current perovskite LPC is much lower due to the series resistance, which may be low enough for solar cells but needs to be reduced by one order of magnitude for LPCs. Moreover, the PCE can be further improved by confining emission angle and resorting to wider bandgap perovskite. Finally, a power output over 7 W/cm2 with PCE over 80% is estimated to be within reach for perovskite LPCs.
Chirality-selective electromagnetically induced transparency in a dielectric metasurface based on chirality transfer between bright and dark modes
Authors: Zhao Shuxia , Gao Lei , Zhang Wei
Published: October 2023

Chiral metasurfaces have wide applications in chiral sensing and functional devices, such as ultrathin circular polarizers. By analytical coupled mode theory and finite-difference time domain simulation, we investigate the chiroptical properties of designed dielectric metasurface with unit cell of corner-stacked nanorods and stacked nanorings, paying attention to the bright-dark-mode coupling effects. With the help of phase modulation and mode hybridization, we can realize chirality transfer from bright modes of chiral nanorods to dark modes of achiral nanorings, which results in chirality-selective transparency due to chirality-selective excitation of binding/antibonding dark modes. Moreover, one can switch between different coupling regimes with a distinct physical effect (Fano effect vs Rabi splitting) by changing only the chirality of the incident field without varying the structure of the metasurface. Based on the mechanisms of chirality transfer and mode hybridization, our designed metasurface has achieved chirality-selective transparent window with tunable central frequency and bandwidth, which provides insight and guidance for the optoelectronic device design.
Two-party quantum identity authentication without entanglement
Authors: Wang Yuqi , Jian Liya , Liu Shiming , Wang Jiaji , Yang Kun , Luo Jiawei
Published: October 2023

This study proposes a two-party quantum identity authentication protocol that does not require the participation of a third party. The protocol can verify the user’s identity without exposing the authentication key information, and it can be implemented with a single-photon state, which does not involve entanglement, enabling it to be combined with existing technologies. The shared key is protected by the protocol and hidden during communication, and the security of the authentication scheme is analyzed and verified under general attack. Further analysis results indicate that this protocol is secure and efficient.
The probability of escape of the products of charged particles resulting from thermonuclear fusion of advanced fuels in the hotspot
Authors: Mahdavi M. , Eftekhari S. M.
Published: October 2023

Establishing fuel ignition conditions depends on the stability of hotspot ignition. Excessive energy escape from the plasma leads to its cooling and shutdown. In this research, the escape probability of charged particles due to the p/11B fuel fusion has been investigated. First, the contribution of p/11B fuel plasma electrons in the Alpha particle energy loss based on the Krokhin and Rozanov (KR) model and then the auxiliary contribution of plasma ions in the Alpha particle energy loss produced in the hotspot of p/11B fuel, based on Li–Petrasso (LP) calculations were analyzed numerically. By calculating the escape fraction of Alpha particles, it has been shown that the contribution of the stopping power of the electrons of the plasma is dominant at both 70 and 170 keV temperatures, which are the starting temperature of the p/11B fuel reaction and the proper ignition temperature, respectively. By increasing the density of p/11B fuel from 300 to 400 g/cc, it can be seen that at a temperature of 70 keV, the penetration depth of Alpha particles decreases from 1200 to 900 μm based on the KR model. It has also been shown that by reducing the number density ratio of boron to protons from 0.3 to 0.2 and 0.1, due to the reduction of the coupling of electrons and ions, which leads to the reduction of collisions with Alpha particles, the stopping length of Alpha particles increases.
An advanced vortex-tube technology for pure ammonia combustion with clean and steady peculiarity
Authors: Ren Shoujun , Li Fan , Jones William P. , Wang Xiaohan
Published: October 2023

The present study investigates the combustion performance of pure ammonia in a stratified vortex-tube reactive flow (SVRF) concerning stability limits, flame topology, pressure fluctuations, and emissions. The results demonstrate that the SVRF enables efficient and stable combustion of ammonia, characterized by uniform flame topology, low NO emissions, and high combustion efficiency. The lean φg stability limits consistently remain below 0.32 within the qf range of 5.0–30.0 l/min. Moreover, the flame topology remains consistently smooth and uniform throughout the process while maintaining a peak heat release above 5.0 × 107 W/m3. Additionally, pressure fluctuation amplitude generally stays within 100 Pa, indicating a remarkably steady combustion process for ammonia burning in the SVRF. The investigation focuses on the multi-field cooperative coupling, which enhances species and enthalpy transport to increase combustion strength, thereby contributing to a larger stability limit. Various criterion numbers are calculated to quantify the aero-/thermo/flame- dynamic stability. It is found that excellent flame-dynamic/thermo-acoustic stability plays a crucial role in achieving steady combustion of pure ammonia, which can be measured by Ra(x) and the “Gain” of the flame transfer function. The degree of synergy between flame disturbance and fluid disturbance, as well as the response of flame disturbance to fluid disturbance in SVRF, is identified as the primary factor influencing different levels of combustion stability performance. Furthermore, a relationship between aero-/thermo-dynamic stability and flame stability has also been discovered. Favorable aero-/thermo-dynamic stability promotes excellent flame-dynamic behavior by suppressing normal direction fluid fluctuation and resulting in more stable intensity and spatial location fluctuations of the flame. Additionally, momentum flux decreases within the interior region, enhancing good flame-dynamic stability when using pure ammonia as fuel.
Grain size in low loss superconducting Ta thin films on c axis sapphire
Authors: Jones Sarah Garcia , Materise Nicholas , Leung Ka Wun , Weber Joel C. , Isakov Brian D. , Chen Xi , Zheng Jiangchang , Gyenis András , Jaeck Berthold , McRae Corey Rae H.
Published: October 2023

In recent years, the implementation of thin-film Ta has led to improved coherence times in superconducting circuits. Efforts to further optimize this materials set have become a focus of the subfield of materials for superconducting quantum computing. It has been previously hypothesized that grain size could be correlated with device performance. In this work, we perform a comparative grain size experiment with α-Ta on c axis sapphire. Our evaluation methods include both room-temperature chemical and structural characterization and cryogenic microwave measurements, and we report no statistical difference in device performance between smaller- and larger-grain-size devices with grain sizes of 924 and 1700 nm2, respectively. These findings suggest that grain size is not correlated with loss in the parameter regime of interest for Ta grown on c axis sapphire, narrowing the parameter space for optimization of this materials set.
Machine learning interatomic potentials as efficient tools for obtaining reasonable phonon dispersions and accurate thermal conductivity: A case study of typical two-dimensional materials
Authors: Cui Chunfeng , Zhang Yuwen , Ouyang Tao , Tang Chao , He Chaoyu , Li Jin , Chen Mingxing , Zhong Jianxing
Published: October 2023

The accurate description of phonon dispersion of two-dimensional (2D) materials demonstrates significance in many research fields of condensed matter physics. In this paper, we systematically calculate the phonon spectra and transport properties of six representative 2D materials (encompassing single-element and binary compounds with flat, buckled, and puckered backbone geometries) by means of density functional theory (DFT) and two machine learning interatomic potentials [MLIPs, on-the-fly machine learning potential (FMLP), and moment tensor potential (MTP)]. The results show that the acoustic out-of-plane flexural (ZA) dispersion of the 2D materials are always and easily exhibiting non-quadratic dispersion phenomena near the center of the Brillouin zone by using the pure DFT calculation method. This phenomenon contradicts physics and reflects intuitively from the non-zero group velocity at Γ point. However, no matter which MLIP (FMLP/MTP) the calculation is based on, it could solve such behavior perfectly, where the ZA mode conforms to the quadratic dispersion relationship in the long-wavelength limit. Our results further demonstrate that compared to the pure DFT calculation, the FMLP and MTP method could quickly and relatively accurately obtain the lattice thermal conductivities of graphene, silicene, phosphorene, SiC, MoS2, and GeS. The findings presented in this work provide a solution about the pseudophysical phenomenon of ZA dispersions in 2D materials with the pure DFT calculation, which will greatly facilitate research areas such as phonon thermal transport, flexural mechanics, and electron–acoustic coupling.
Identification, structural, and biophysical characterization of a positive modulator of human Kv3.1 channels
Authors: Chen Yun-Ting , Hong Mee Ra , Zhang Xin-Jun , Kostas James , Li Yuxing , Kraus Richard L. , Santarelli Vincent P. , Wang Deping , Gomez-Llorente Yacob , Brooun Alexei , Strickland Corey , Soisson Stephen M. , Klein Daniel J. , Ginnetti Anthony T. , Marino Michael J. , Stachel Shawn J. , Ishchenko Andrii
Published: October 2023

Voltage-gated potassium channels (Kv) are tetrameric membrane proteins that provide a highly selective pathway for potassium ions (K+) to diffuse across a hydrophobic cell membrane. These unique voltage-gated cation channels detect changes in membrane potential and, upon activation, help to return the depolarized cell to a resting state during the repolarization stage of each action potential. The Kv3 family of potassium channels is characterized by a high activation potential and rapid kinetics, which play a crucial role for the fast-spiking neuronal phenotype. Mutations in the Kv3.1 channel have been shown to have implications in various neurological diseases like epilepsy and Alzheimer’s disease. Moreover, disruptions in neuronal circuitry involving Kv3.1 have been correlated with negative symptoms of schizophrenia. Here, we report the discovery of a novel positive modulator of Kv3.1, investigate its biophysical properties, and determine the cryo-EM structure of the compound in complex with Kv3.1. Structural analysis reveals the molecular determinants of positive modulation in Kv3.1 channels by this class of compounds and provides additional opportunities for rational drug design for the treatment of associated neurological disorders.
Space weather disrupts nocturnal bird migration
Authors: Gulson-Castillo Eric R. , Van Doren Benjamin M. , Bui Michelle X. , Horton Kyle G. , Li Jing , Moldwin Mark B. , Shedden Kerby , Welling Daniel T. , Winger Benjamin M.
Published: October 2023

Space weather, including solar storms, can impact Earth by disturbing the geomagnetic field. Despite the known dependence of birds and other animals on geomagnetic cues for successful seasonal migrations, the potential effects of space weather on organisms that use Earth’s magnetic field for navigation have received little study. We tested whether space weather geomagnetic disturbances are associated with disruptions to bird migration at a macroecological scale. We leveraged long-term radar data to characterize the nightly migration dynamics of the nocturnally migrating North American avifauna over 22 y. We then used concurrent magnetometer data to develop a local magnetic disturbance index associated with each radar station (ΔBmax), facilitating spatiotemporally explicit analyses of the relationship between migration and geomagnetic disturbance. After controlling for effects of atmospheric weather and spatiotemporal patterns, we found a 9 to 17% decrease in migration intensity in both spring and fall during severe space weather events. During fall migration, we also found evidence for decreases in effort flying against the wind, which may represent a depression of active navigation such that birds drift more with the wind during geomagnetic disturbances. Effort flying against the wind in the fall was most reduced under both overcast conditions and high geomagnetic disturbance, suggesting that a combination of obscured celestial cues and magnetic disturbance may disrupt navigation. Collectively, our results provide evidence for community-wide avifaunal responses to geomagnetic disturbances driven by space weather during nocturnal migration.
A triple-synergistic small-molecule sulfur cathode promises energetic Cu-S electrochemistry
Authors: Lin Xia , Zhang Junwei , Yan Huihui , Xu Jiaxi , Miao Zhonghao , Shu Guangchang , Zhao Shuyuan , Zhang Tianyuan , Yu Haoxiang , Yan Lei , Zhang Liyuan , Shu Jie
Published: October 2023

Metal-sulfur batteries have received great attention for electrochemical energy storage due to high theoretical capacity and low cost, but their further development is impeded by low sulfur utilization, poor electrochemical kinetics, and serious shuttle effect of the sulfur cathode. To avoid these problems, herein, a triple-synergistic small-molecule sulfur cathode is designed by employing N, S co-doped hierarchical porous bamboo charcoal as a sulfur host in an aqueous Cu-S battery. Expect the enhanced conductivity and chemisorption induced by N, S synergistic co-doping, the intrinsic synergy of macro-/meso-/microporous triple structure also ensures space-confined small-molecule sulfur as high utilization reactant and effectively alleviates the volume expansion during conversion reaction. Under a further joint synergy between hierarchical structure and heteroatom doping, the resulting sulfur cathode endows the Cu-S battery with outstanding electrochemical performance. Cycled at 5 A g
−1
, it can deliver a high reversible capacity of 2,509.8 mAh g
−1
with a good capacity retention of 97.9% after 800 cycles. In addition, a flexible hybrid pouch cell built by a small-molecule sulfur cathode, Zn anode, and gel electrolytes can firmly deliver high average operating voltage of about 1.3 V with a reversible capacity of over 2,500 mAh g
−1
under various destructive conditions, suggesting that the triple-synergistic small-molecule sulfur cathode promises energetic metal-sulfur batteries.
Splitting of Degenerate Superatomic Molecular Orbitals Determined by Point Group Symmetry
Authors: Wang 王 Rui 瑞 , Li 李 Jiarui 佳芮 , Liu 刘 Zhonghua 中华 , Wan 万 Chenxi 晨曦 , Wang 王 Zhigang 志刚
Published: October 2023

We first confirm an idea obtained from first-principles calculations, which is in line with symmetry theory: Although superatomic molecular orbitals (SAMOs) can be classified according to their angular momentum similar to atomic orbitals, SAMOs with the same angular momentum split due to the point group symmetry of superatoms. Based on this idea, we develop a method to quantitatively modulate the splitting spacing of molecular orbitals in a superatom by changing its structural symmetry or by altering geometric parameters with the same symmetry through expansion and compression processes. Moreover, the modulation of the position crossover is achieved between the lowest unoccupied molecular orbital and the highest occupied molecular orbital originating from the splitting of different angular momenta, leading to an effective reduction in system energy. This phenomenon is in line with the implication of the Jahn–Teller effect. This work provides insights into understanding and regulating the electronic structures of superatoms.
Students’ confusions about the electric field of a uniformly moving charge
Authors: Žugec Petar , Horvatić Davor , Smolić Ivica
Published: October 2023

In light of a recent direct experimental confirmation of a Lorentz contraction of Coulomb field (an electric field of a point charge in a uniform motion), we revisit some common confusions related to it, to be mindful of in teaching the subject. These include questions about the radial nature of the field, the role of the retardation effect due to a finite speed of information transfer and some issues related to a depiction of Coulomb field by means of the Lorentz contracted field lines.
An elementary approach to simulating the perihelion of Mercury
Authors: Williams Hollis
Published: October 2023

The relativistic correction to the precession of the perihelion of Mercury provided key evidence for the accuracy of general relativity as a theory of gravity. This example still has a large amount of potential to introduce students to the power of numerical simulations in theoretical physics, but existing approaches may be too detailed for many students and involve them beginning to learn a programming language at the same time. In this article, we take a simpler approach which uses as little coding as possible. The equation for the orbit of a planet is solved with and without relativistic corrections. It is shown that there is precession of the perihelion in the relativistic case, whereas in the Newtonian case, the orbit does not rotate about the origin. Quantitative information is extracted on the precession of the perihelion of Mercury and shown to match with observations.
Simultaneous dual-wavelength digital holographic microscopy as a tool for the analysis of keratoacanthoma skin samples
Authors: Palacios-Ortega Natalith , Hernández-Montes María Del Socorro , Santoyo Fernando Mendoza , Flores-Moreno Mauricio , Ibarra Manuel de la Torre , Luis-Noriega Daniel , Méndez-Sashida Pedro G
Published: October 2023

A keratoacanthoma (KA) skin tumor is usually caused by sun exposure and may be an alert sign prior to the development of a more aggressive tumor or skin cancer. Studying the shape of the KA cells and their 3D rendering visualization are important parameters to prevent its evolution to higher stages of tumor cells or skin cancer. KA cells shape can be obtained through digital holographic microscopy; for that purpose, a setup with two illumination wavelengths (532 and 638 nm) is implemented to render a synthetic wavelength of 3.2 μm that avoids wrapping the optical phase of the processed holograms and increases measurement range. To recover the optical phase, two off-axis digital holograms are simultaneously recorded at each wavelength. From the processed hologram height variations, the shape and length of KA cells, as well as the stratum corneum epidermal layer, are obtained as phase images. The results achieved aid to discriminate healthy from malignant cells.
Electronic and magnetic properties of layered M3Si2Te6 (M = alkaline earth and transition metals)
Authors: Li Bowen , Bai Haoyun , Yu Zhichao , Li Yutong , Kwok Chi Tat , Feng Wenlin , Wang Shuangpeng , Ng Kar Wei
Published: October 2023

Recently, a new layered material, Mn3Si2Te6, was identified to be a semiconductor with nodal-line topological property and ferrimagnetic ground state. In this work, we propose a series of structures, M3Si2Te6 (M = alkaline earth and transition metals), and systematically investigate their mechanical, magnetic and electronic properties, and the strain effect to enrich the family of the layered materials for practical applications. We find 13 stable M3Si2Te6, including 5 semiconductors (M = Ca, Sr, Fe, Ru and Os) and 8 metals (M = Sc, Ti, Nb, Ta, Cr, Mo, W and Tc). Two structures (M = Ti and Cr) are antiferromagnetic (AFM), while other structures are non-magnetic (NM). Similar to Mn3Si2Te6, the AFM structures exhibit magnetic anisotropy energies (MAEs) and semiconductors have anisotropic electron effective masses. We further show that compressions along the z-axis can effectively tune the electronic and magnetic properties, such as the semiconductor-metal and NM-AFM transition in Fe3Si2Te6, the two-fold degeneracy of the valence band maximums in Sr3Si2Te6, as well as the reduced MAE for all magnetic structures. These results demonstrate the diverse properties of the layered M3Si2Te6 family and provide promising theoretical predictions for the future design of new layered materials.
An explainable deep learning approach for detection and isolation of sensor and machine faults in predictive maintenance paradigm
Authors: Sinha Aparna , Das Debanjan
Published: October 2023

The predictive health maintenance techniques identify the machine faults by analyzing the data collected by low-cost sensors assuming that sensors are free from any faults. However, aging and environmental condition cause sensors also be faulty, leading to incorrect interpretations of the collected data and subsequently resulting in erroneous machine health predictions. To mitigate this problem, this paper proposes a hybrid model that can differentiate between sensor and system faults. The data used for training the model is collected from a power system hardware setup by experimental procedures. A convolutional neural network (CNN) model is used to extract optimized features from the raw data automatically, which are then fed to the eXtreme Gradient Boosting (XGBoost) model for sensor and machine fault isolation with an overall accuracy of 98.15%. The data having sensor fault was then fed to a deep autoencoder, which eliminated the sensor fault components and reconstructed the data with an average root mean square error of 0.0576. Thereafter, the corrected signal was used to detect the system fault using the hybrid CNN-XGBoost model with 99.77% accuracy. Therefore, by isolating the sensor faults, the proposed technique establishes better confidence in predictive maintenance. Further, explainable AI has been utilized to interpret the model prediction in human-understandable terms in order to increase trustworthiness.
Superconductivity of Li doped BSCCO mesoscopic fiber
Authors: Zeng Xian-Lin , Wiederhold Alex , Koblischka Michael R , Wang Di , Fawey Mohammed Hammad , Hartmann Uwe
Published: October 2023

Mesoscopic Li doped BSCCO fibres are synthesized by the electrospinning technology and the sequent sintering treatment. With the assistance of high resolution energy-dispersive x-ray spectroscopy detector in the Aberration-corrected transmission electron microscopy, we discovered hidden CuO grains and separated Bi-2212 phases, which is proved by the existence of fishtail effect in the magnetization loops. The electric measurement is fulfilled via four probe method with the help of focus ion beam operation. A non-trivial resistance behaviour appears, which can be attributed to its polycrystalline and superconducting phase separation features.
The on-chip scanning probe with dual niobium nitride nanoscale superconducting quantum interference devices for magnetic imaging at the high temperature
Authors: Zhang Denghui , Pan Yinping , Wu Guangting , Yu Shujie , Zhong Xianghai , Wang Yue , Liu Xiaoyu , Wu Ling , Peng Wei , Zhang Lu , Chen Lei , Wang Zhen
Published: October 2023

The scanning superconducting quantum interference device (SQUID) microscope is a powerful tool for investigating the microscale magnetic properties of quantum materials. However, the low operating temperature of SQUIDs limits the application of the microscope. In this work, we developed an on-chip probe with dual niobium nitride (NbN) nano-SQUIDs for scanning SQUID microscope. The working temperature of the NbN nano-SQUID on-chip probe was up to 8 K, and it enabled the magnetic imaging of samples at the temperature up to 128 K. We used a gradiometric readout scheme for dual nano-SQUIDs in one probe to reduce the influence of the background magnetic field. Furthermore, we demonstrated the capabilities of both topographic and current imaging by the on-chip probe with spatial resolutions of 1 μm and 2 μm, respectively. The advantage of the probe at the high temperature was also demonstrated by the investigation of the superconducting vortices distribution in the yttrium-barium-copper-oxide film.
Compressible two-dimensional turbulence: cascade reversal and sensitivity to imposed magnetic field
Authors: Fouxon Itzhak , Kritsuk Alexei G , Mond Michael
Published: October 2023

We study the impact of compressibility on two-dimensional turbulent flows, such as those modeling astrophysical disks. We demonstrate that the direction of cascade undergoes continuous transition as the Mach number Ma increases, from inverse at Ma = 0, to direct at

M
a
=
∞

. Thus, at

M
a
∼
1

comparable amounts of energy flow from the pumping scale to large and small scales, in accord with previous data. For supersonic turbulence with

M
a
≫
1

the cascade is direct, as in three dimensions, which results in multifractal density field. For that regime (

M
a
≫
1

) we derive a Kolmogorov-type law for potential forcing and obtain an explicit expression for the third order correlation tensor of the velocity. We further show that all third order structure functions are zero up to first order in the inertial range scales, which is in sharp contrast with incompressible turbulence where the third order structure function, that describes the energy flux associated with the energy cascade is non-zero. The properties of compressible turbulence have significant implications on the amplification of magnetic fields in conducting fluids. We thus demonstrate that imposing external magnetic field on compressible flows of conducting fluids allows to manipulate the flow producing possibly large changes even at small Mach numbers. Thus Zeldovich’s antidynamo theorem, by which at Ma = 0 the magnetic field is zero in the steady state, must be used with caution. Real flows have finite Ma and, however small it is, for large enough values of I, the magnetic flux through the disk, the magnetic field changes the flow appreciably, or rearranges it completely. This renders the limit Ma → 0 singular for non-zero values of I. Of particular interest is the effect of the density multifractality, at

M
a
≫
1

which is relevant for astrophysical disks. We demonstrate that in that regime, in the presence of non-zero I the magnetic field energy is enhanced by a large factor as compared to its estimates based on the mean field. Finally, based on the insights described above, we propose a novel two-dimensional Burgers’ turbulence, whose three-dimensional counterpart is used for studies of the large-scale structure of the Universe, as a model for supersonic two-dimensional magnetohydrodynamic flows.
Possibility of using machine learning methods to reconstruct solid body parameters during laser-induced desorption analysis
Authors: Stepanenko A A , Kashin D A , Gasparyan Yu M
Published: October 2023

The possibility of using machine learning methods for solving the inverse problem of the laser-induced desorption quadrupole mass-spectrometry (LID-QMS) diagnostic is studied. The formulation of the problem is given, and a general scheme of its solution is proposed. A test model of gas transport in a solid body is considered, which is used to construct a database of gas transport parameters in the sample. The application of the synthetic data and machine learning methods, viz. the interpolation technique, the method of K nearest neighbors, and the neural networks, for solving the LID-QMS inverse problem is investigated. The advantages and disadvantages of each approach are discussed.
Beyond 3×2-point cosmology: the integrated shear and galaxy 3-point correlation functions
Authors: Halder Anik , Gong Zhengyangguang , Barreira Alexandre , Friedrich Oliver , Seitz Stella , Gruen Daniel
Published: October 2023

We present the integrated 3-point correlation functions (3PCF) involving both the cosmic shear and the galaxy density fields. These are a set of higher-order statistics that describe the modulation of local 2-point correlation functions (2PCF) by large-scale features in the fields, and which are easy to measure from galaxy imaging surveys. Based on previous works on the shear-only integrated 3PCF, we develop the theoretical framework for modelling 5 new statistics involving the galaxy field and its cross-correlations with cosmic shear. Using realistic galaxy and cosmic shear mocks from simulations, we determine the regime of validity of our models based on leading-order standard perturbation theory with an MCMC analysis that recovers unbiased constraints of the amplitude of fluctuations parameter A
s and the linear and quadratic galaxy bias parameters b
1 and b
2. Using Fisher matrix forecasts for a DES-Y3-like survey, relative to baseline analyses with conventional 3×2PCFs, we find that the addition of the shear-only integrated 3PCF can improve cosmological parameter constraints by 20–40%. The subsequent addition of the new statistics introduced in this paper can lead to further improvements of 10–20%, even when utilizing only conservatively large scales where the tree-level models are valid. Our results motivate future work on the galaxy and shear integrated 3PCFs, which offer a practical way to extend standard analyses based on 3×2PCFs to systematically probe the non-Gaussian information content of cosmic density fields.
Transition from a filamentary mode to a diffuse one with varying distance from needle to stream of an argon plasma jet
Authors: Xu 许 Hui-Min 慧敏 , Gao 高 Jing-Ge 敬格 , Jia 贾 Peng-Ying 鹏英 , Ran 冉 Jun-Xia 俊霞 , Chen 陈 Jun-Yu 俊宇 , Li 李 Jin-Mao 金懋
Published: October 2023

Plasma jet has extensive application potentials in various fields, which normally operates in a diffuse mode when helium is used as the working gas. However, when less expensive argon is used, the plasma jet often operates in a filamentary mode. Compared to the filamentary mode, the diffuse mode is more desirable for applications. Hence, many efforts have been exerted to accomplish the diffuse mode of the argon plasma jet. In this paper, a novel single-needle argon plasma jet is developed to obtain the diffuse mode. It is found that the plasma jet operates in the filamentary mode when the distance from the needle tip to the central line of the argon stream (d) is short. It transits to the diffuse mode with increasing d. For the diffuse mode, there is always one discharge pulse per voltage cycle, which initiates at the rising edge of the positive voltage. For comparison, the number of discharge pulse increases with an increase in the peak voltage for the filamentary mode. Fast photography reveals that the plasma plume in the filamentary mode results from a guided positive streamer, which propagates in the argon stream. However, the plume in the diffuse mode originates from a branched streamer, which propagates in the interfacial layer between the argon stream and the surrounding air. By optical emission spectroscopy, plasma parameters are investigated for the two discharge modes, which show a similar trend with increasing d. The diffuse mode has lower electron temperature, electron density, vibrational temperature, and gas temperature compared to the filamentary mode.
Tailoring resonant magnetic perturbation to optimize fast-ion confinement during ELM control in KSTAR
Authors: Yang S.M. , Park J.-K. , Kim H.S. , Podesta M. , Kang J.S. , Rhee T.
Published: October 2023

3D resonant magnetic perturbation (RMP) is one promising way to control edge localized modes that can cause excessive material erosion of tokamak first walls. However, RMP can lead to undesired degradation of plasma confinement, including fast-particle losses, which can impact the performance and safety of the reactor. This work investigates the optimization of the poloidal spectrum of the 3D field to optimize fast ion confinement during edge localized mode (ELM) suppression. In the initial step, the validity of the modeling framework is tested against experimental data. Simulations successfully replicate an increase in poloidal limiter temperature with different poloidal spectra. Then, the simulation shows improvement of fast ion confinement with a reduction of core resonant response, while edge resonant magnetic fields are maintained above the threshold to sustain the ELM suppression. Reduction of the core resonant fields keeps the Kolmogorov–Arnold–Moser surface and reduces the fast particle losses due to the stochastic magnetic field lines. The results highlight the potential of edge localization of the resonant fields to enhance the performance of fusion reactors, but further investigation is needed to improve the validation of this approach.
Electromagnetic load evaluating and optimizing approach of the blanket system during VDEs considering halo current
Authors: Lei Mingzhun , Liu Zhao , Wu Qigang , Liu Sumei , Wang Ming
Published: October 2023

In most scenarios, the vertical displacement event (VDE) represents the most extreme electromagnetic (EM) event within the tokamak device. The significant EM loads experienced during this event have the potential to compromise the structural stability of in-vessel components. This study investigates the EM loads on the water-cooled ceramic breeder blanket system of China Fusion Engineering Test Reactor (CFETR) using finite element analysis methods in two characteristic events: hot-VDE and cold-VDE. The study discusses the EM load effects resulting from changes in magnetic flux and induced electromotive force, respectively, with a specific focus on halo currents. The results reveal that, with similar current quech time, the difference in EM load on the blanket system during the VDEs primarily depends on the halo currents. When the electrical connection of the back supporting structure (BSS) is open, the halo current path within the blanket system and vacuum vessel (VV) changes, and a substantial portion of the halo current in the blanket system is conducted to the VV via the BSS. Consequently, a portion of the EM load on the blankets and BSS is transferred to the VV due to the transfer of halo current. Inspired by this, the conceptual use of ‘shunts’ is proposed to provide a dedicated circuit for shunting halo currents away from critical device components, such as the VV and blankets. This approach allows for the sharing of EM loads caused by halo currents and reduces the threat posed by halo currents to the structural integrity of these essential components.
Interplay of degeneracy and non-degeneracy in fluctuation propagation in coherent feed-forward loop motif
Authors: Subhra Roy Tuhin , Nandi Mintu , Chaudhury Pinaki , Chattopadhyay Sudip , Banik Suman K
Published: October 2023

We present a stochastic framework to decipher fluctuation propagation in classes of coherent feed-forward loops (CFFLs). The systematic contribution of the direct (one-step) and indirect (two-step) pathways is considered to quantify fluctuations of the output node. We also consider both additive and multiplicative integration mechanisms of the two parallel pathways (one-step and two-step). Analytical expression of the output node’s coefficient of variation shows contributions of intrinsic, one-step, two-step, and cross-interaction in closed form. We observe a diverse range of degeneracy and non-degeneracy in each of the decomposed fluctuation terms and their contribution to the overall output fluctuations of each CFFL motif. The analysis of output fluctuations reveals a maximal level of fluctuations of the CFFL motif of type 1.
Ultra low background Micromegas detectors for BabyIAXO solar axion search
Authors: Ferrer-Ribas E. , Altenmüller K. , Biasuzzi B. , Castel J.F. , Cebrián S. , Dafni T. , Desch K. , Díez-Ibañez D. , Galán J. , Galindo J. , García J.A. , Giganon A. , Goblin C. , Irastorza I.G. , Kaminski J. , Luzón G. , Margalejo C. , Mirallas H. , Navick X.F. , Obis L. , Ortiz de Solórzano A. , von Oy J. , Papaevangelou T. , Pérez O. , Picatoste E. , Ruz J. , Schiffer T. , Schmidt S. , Segui L. , Vogel J.K.
Published: October 2023

The International AXion Observatory (IAXO) is a large scale axion helioscope that will look for axions and axion-like particles produced in the Sun with unprecedented sensitivity. BabyIAXO is an intermediate experimental stage that will be hosted at DESY (Germany) and that will test all IAXO subsystems serving as a prototype for IAXO but at the same time as a fully-fledged helioscope with potential for discovery.

One of the crucial components of the project is the ultra-low background X-ray detectors that will image the X-ray photons produced by axion conversion in the experiment. The baseline detection technology for this purpose are Micromegas (Microbulk) detectors. We will show the quest and the strategy to attain the very challenging levels of background targeted for BabyIAXO that need a multi-approach strategy coming from ground measurements, screening campaigns of components of the detector, underground measurements, background models, in-situ background measurements as well as powerful rejection algorithms. First results from the commissioning of the BabyIAXO prototype will be shown.
Power efficient MoS2 synaptic devices based on Maxwell–Wagner interfacial charging in binary oxides
Authors: Zou Jingyi , Lin Sen , Huang Tianyi , Liu Hefei , Liu Yushuang , Zhong Yibai , Lin Yuxuan Cosmi , Wang Han , Shen Sheng , Xu Min , Zhang Xu
Published: October 2023

Synaptic devices with tunable weight hold great promise in enabling non-von Neumann architecture for energy efficient computing. However, conventional metal-insulator-metal based two-terminal memristors share the same physical channel for both programming and reading, therefore the programming power consumption is dependent on the synaptic resistance states and can be particularly high when the memristor is in the low resistance states. Three terminal synaptic transistors, on the other hand, allow synchronous programming and reading and have been shown to possess excellent reliability. Here we present a binary oxide based three-terminal MoS2 synaptic device, in which the channel conductance can be modulated by interfacial charges generated at the oxide interface driven by Maxwell-Wagner instability. The binary oxide stack serves both as an interfacial charge host and gate dielectrics. Both excitatory and inhibitory behaviors are experimentally realized, and the presynaptic potential polarity can be effectively controlled by engineering the oxide stacking sequence, which is a unique feature compared with existing charge-trap based synaptic devices and provides a new tuning knob for controlling synaptic device characteristics. By adopting a three-terminal transistor structure, the programming channel and reading channel are physically separated and the programming power consumption can be kept constantly low (∼50 pW) across a wide dynamic range of 105. This work demonstrates a complementary metal oxide semiconductor compatible approach to build power efficient synaptic devices for artificial intelligence applications.
Stress relaxation behavior of low carbon steel at different temperatures
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Authors: Zuo Shanchao , Wang Danchen , Yang Changqi , Hu Peipei , Bi Ran , Du Bing , Wang Decheng
Published: October 2023

In this paper, the stress relaxation behavior of Q235 with the initial tensile stress of 70, 85 and 100 MPa were investigated at different temperature. Based on the thermal activation theory, the stress relaxation model of Q235 steel was established, and the physical mechanism and deformation process in the stress relaxation process were revealed. The results shows that with the increase of temperature or initial stress, the nominal activation volume decreases, but the strain rate and the strain rate sensitivity coefficient increase. The repeated stress relaxation test shows that the stress release amount decreases with the increase of the number of cycles, and the higher the temperature, the smaller the effect of the number of cycles. Under the action of temperature and stress, the dislocation starts to move from the disordered bending shape in the original sample to the flat shape gradually. Moreover, the dislocation density decreases to less than 47.8% of the initial sample as the temperature increases and the initial stress decreases. It can be concluded that the dislocation motion is the core mechanism of stress relaxation of Q235 steel.
Quantum eigenvector continuation for chemistry applications
Authors: Mejuto-Zaera Carlos , Kemper Alexander F
Published: October 2023

A typical task for classical and quantum computing in chemistry is finding a potential energy surface (PES) along a reaction coordinate, which involves solving the quantum chemistry problem for many points along the reaction path. Developing algorithms to accomplish this task on quantum computers has been an active area of development, yet finding all the relevant eigenstates along the reaction coordinate remains a difficult problem, and determining PESs is thus a costly proposal. In this paper, we demonstrate the use of a eigenvector continuation—a subspace expansion that uses a few eigenstates as a basis—as a tool for rapidly exploring PESs. We apply this to determining the binding PES or torsion PES for several molecules of varying complexity. In all cases, we show that the PES can be captured using relatively few basis states; suggesting that a significant amount of (quantum) computational effort can be saved by making use of already calculated ground states in this manner.
Unrecorded alcohol consumption in Lithuania: a modelling study for 2000–2021
Authors: Štelemėkas Mindaugas , Goštautaitė Midttun Nijolė , Lange Shannon , Liutkutė-Gumarov Vaida , Manthey Jakob , Miščikienė Laura , Petkevičienė Janina , Radišauskas Ričardas , Rehm Jürgen , Trišauskė Justina , Telksnys Tadas , Thompson Mark James
Published: October 2023

The aim of the study was to estimate unrecorded alcohol consumption in Lithuania for the period 2000–2021 using an indirect method for modelling consumption based on official consumption data and indicators of alcohol-related harm. Methodology employed for estimating the unrecorded alcohol consumption was proposed by Norström and was based on the country’s 2019 European Health Interview Survey and indicators of fully alcohol-attributable mortality. The proportion of unrecorded alcohol consumption was estimated as 8.30% (95% CI 7.7–8.9%) for 2019 in Lithuania. The estimated total (recorded and unrecorded) alcohol per capita consumption among individuals 15 years of age and older in 2019 was 12.2 L of pure alcohol, 1.01 (95% CI 0.94–1.09%) L of which is likely unrecorded. The lowest unrecorded alcohol level was estimated for 2009 and 2014, while 2018 had the highest level (i.e. 9.33% of total alcohol per capita consumption). Unrecorded alcohol consumption in Lithuania is likely to be modest when compared to recorded alcohol consumption, the latter of which still remains a major challenge to public health.