bluuebunny/crossref_metadata_2025 huggingface dataset:
Microstructure, mechanical and electrochemical properties of wire-arc additively manufactured duplex stainless steel
Authors: Liu Aobo , Yin Bangzhao , Zhang Di , Wen Peng
Published: December 2022

Wire-arc additively manufactured (WAAM) super duplex stainless steels (DSS) 2594 walls were fabricated to investigate the microstructure of different regions, including top, body and root as well as the influence of microstructure on mechanical and electrochemical properties. The microstructure was composed of ferrite and austenite with a few nitride precipitates. The ferrite content decreased from top to root. The average hardness increased slightly from top to root. The ultimate tensile strength of different regions varied slightly, comparable to that of the hot-rolled plate. Compared with those in vertical direction, samples in the horizontal direction had higher strength and lower elongation. The corrosion resistance ranked as root ≈ body > hot-rolled > top.
α-Tubulin detyrosination links the suppression of MCAK activity with taxol cytotoxicity
Authors: Lopes Danilo , Seabra Alexandre L. , Orr Bernardo , Maiato Helder
Published: December 2022

α/β-Tubulin posttranslational modifications (PTMs) generate microtubule diversity, but whether they account for cancer cell resistance to microtubule-targeting drugs remains unknown. Here, we performed a pilot dissection of the “cancer tubulin code” using the NCI-60 cancer cell panel. We found that acetylated, detyrosinated, and ∆2-α-tubulin that typically accumulate on stable microtubules were uncoupled in many cancer cells. Acetylated α-tubulin did not affect microtubule dynamics, whereas its levels correlated with, but were not required for, taxol-induced cytotoxicity. In contrast, experimental increase of α-tubulin detyrosination, and/or depletion of the detyrosination-sensitive microtubule-depolymerizing enzyme MCAK, enhanced taxol-induced cytotoxicity by promoting cell death in mitosis and the subsequent interphase, without causing a cumulative effect. Interestingly, only increased detyrosinated α-tubulin aggravated taxol-induced spindle multipolarity. Overall, we identified high α-tubulin acetylation as a potential biomarker for cancer cell response to taxol and uncovered a mechanistic link between α-tubulin detyrosination and the suppression of MCAK activity in taxol-induced cytotoxicity, likely by promoting chromosome missegregation, regardless of spindle defects.
Ion channel regulation of gut immunity
Authors: Feng Jing , Xie Zili , Hu Hongzhen
Published: December 2022

Mounting evidence indicates that gastrointestinal (GI) homeostasis hinges on communications among many cellular networks including the intestinal epithelium, the immune system, and both intrinsic and extrinsic nerves innervating the gut. The GI tract, especially the colon, is the home base for gut microbiome which dynamically regulates immune function. The gut’s immune system also provides an effective defense against harmful pathogens entering the GI tract while maintaining immune homeostasis to avoid exaggerated immune reaction to innocuous food and commensal antigens which are important causes of inflammatory disorders such as coeliac disease and inflammatory bowel diseases (IBD). Various ion channels have been detected in multiple cell types throughout the GI tract. By regulating membrane properties and intracellular biochemical signaling, ion channels play a critical role in synchronized signaling among diverse cellular components in the gut that orchestrates the GI immune response. This work focuses on the role of ion channels in immune cells, non-immune resident cells, and neuroimmune interactions in the gut at the steady state and pathological conditions. Understanding the cellular and molecular basis of ion channel signaling in these immune-related pathways and initial testing of pharmacological intervention will facilitate the development of ion channel–based therapeutic approaches for the treatment of intestinal inflammation.
CCAUV.W-K2 final report - key comparison CCAUV.W-K2: calibration of hydrophones in the frequency range from 250 Hz to 500 kHz
Authors: Robinson S P , Harris P M , Ford B , Ablitt J , Yi Chen , Biber Alper , Corakci Ata Can , Costa-Felix Rodrigo , Crocker Steven , Isaev Alexander , Tyalimpi Vumile , Latha G
Published: December 2022

Main text

This report is the final report for key comparison CCAUV.W-K2. This key comparison covers primary free-field standards for sound in water at frequencies between 250 Hz and 500 kHz. This project is one of the key comparisons organised under the auspices of the Consultative Committee on Acoustics, Ultrasound and Vibration (CCAUV) of the CIPM.

This report has the status of a Final Report and has been submitted to the Key Comparison Database (KCDB). In the report, the results of participants are presented with the Key Comparison Reference Values and Degrees of Equivalence. The results are calculated according to the procedures agreed after consideration of the Draft A1 and A2 reports, and the Draft B report has been approved by the CCAUV. All participants have had the opportunity to give final agreement on the contents and amendments have been made to account for their comments.

In many respects, the comparison has been a success with good agreement achieved over an extended lower frequency range compared to the previous CCAUV.W-K1 comparison, the lower frequency limit for CCAUV.W-K2 being extended down by two octaves to 250 Hz. The generally more difficult frequency range from 100 kHz to 500 kHz has also shown very good agreement between the participants. However, in the range 60 kHz to 100 kHz the agreement was not as good, with three participants exhibiting some discrepant results.

To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database https://www.bipm.org/kcdb/.

The final report has been peer-reviewed and approved for publication by the CCAUV, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).
Classical and quantum bicosmology with noncommutativity
Authors: Kan Nahomi , Aoyama Takuma , Shiraishi Kiyoshi
Published: December 2022

Recently, Falomir, Gamboa, Méndez, Gondolo and Maldonado proposed a bicosmology scenario for solving some cosmological problems related to inflation, dark matter, and thermal history of the Universe (Falomiret al(2017Phys. Rev.D96083534); Falomiret al(2018Phys. Lett.B785399); Falomiret al(2020Symmetry12435); Maldonado and Méndez (2021Phys. Rev.D103123505)) . Their plan is to introduce noncommutativity into the momentum space of the two scale factors. In the present paper, we revisit their model and first consider exact classical solutions in the model with constant noncommutativity between dynamical variables and between canonical momenta. We also hypothesize that the noncommutativity appears when the scale factors are small, and show the behavior of the classical solution in that case with momentum-space noncommutativity. Finally, we write down the Wheeler–DeWitt equation in that case and examine the behavior of the solution.
Energy equations for projectiles with linear and quadratic drag
Authors: Bradshaw John L
Published: December 2022

Although linear and quadratic drag are treated early in upper-level undergraduate mechanics courses, energy dissipation due to drag is not. In this paper, energy equations with exact analytic formulas for dissipation due to air resistance are developed for projectiles using linear and quadratic drag models, based on the work–energy theorem. Examples with analytic results for specific cases are presented for quadratic drag in one dimension, and linear drag in one and two dimensions suggested as student assignments. Similarly, three numerical examples of energy dissipation showing kinetic, potential, and/or dissipated energy versus either time or distance are presented, suggested as assignments that students could code and graph in a spreadsheet application.
Disconnected entanglement entropy as a marker of edge modes in a periodically driven Kitaev chain
Authors: Mondal Saikat , Sen Diptiman , Dutta Amit
Published: December 2022

We study the disconnected entanglement entropy (DEE) of a Kitaev chain in which the chemical potential is periodically modulated with δ-function pulses within the framework of Floquet theory. For this driving protocol, the DEE of a sufficiently large system with open boundary conditions turns out to be integer-quantized, with the integer being equal to the number of Majorana edge modes localized at each edge of the chain generated by the periodic driving, thereby establishing the DEE as a marker for detecting Floquet Majorana edge modes. Analyzing the DEE, we further show that these Majorana edge modes are robust against weak spatial disorder and temporal noise. Interestingly, we find that the DEE may, in some cases, also detect the anomalous edge modes which can be generated by periodic driving of the nearest-neighbor hopping, even though such modes have no topological significance and not robust against spatial disorder. We also probe the behavior of the DEE for a kicked Ising chain in the presence of an integrability breaking interaction which has been experimentally realized.
Prediction of erbium–nitrogen compounds as high-performance high-energy-density materials
Authors: Cai Huapeng , Wang Xin , Zheng Yueshao , Jiang Xing-xing , Zeng Jiang , Feng Yexin , Chen Keqiu
Published: December 2022

To explore high-energy-density materials, intense attention has been focused on how to stabilize the N–N bond in nitrogen-rich compounds. Here, we report several stable phases of erbium–nitrogen compounds ErN
x
as high-energy-density materials. Specifically, the phase diagrams of stable high-pressure structures Immm-ErN2, C2-ErN3, P

1
ˉ

-ErN4, and P

1
ˉ

-ErN6, are theoretically studied by combining first-principles calculation with particle swarm optimization algorithm. In these erbium–nitrogen compounds, the N–N bonds are stabilized as diatomic quasi-molecule N2, helical-like nitrogen chains, armchair nitrogen chains, and armchair–anti-armchair nitrogen chains, respectively. Among them, the P

1
ˉ

-ErN6 harbors excellent stability at high thermal up to 1000 K. More importantly, the P

1
ˉ

-ErN6 has outstanding explosive performance with high-energy-density of 1.30 kJ g−1, detonation velocity of 10.87 km s−1, and detonation pressure of 812.98 kbar, which shows its promising application prospect as high-energy-density materials.
Hierarchical dispersion Lempel–Ziv complexity for fault diagnosis of rolling bearing
Authors: Li Yongjian , Tan Li , Xiao Meng , Xiong Qing
Published: December 2022

The fault information of rolling bearings is generally contained in vibration signals. How to efficiently unearth fault information from the raw signals is the key to detecting and evaluating the health condition of mechanical equipment. Therefore, a hierarchical dispersion Lempel–Ziv complexity (HDLZC) feature extraction method is developed in this paper to improve the accuracy of fault diagnosis. In this method, dispersion theory addresses the deficiency of Lempel–Ziv complexity, and can obtain more fault features from the raw signal. Second, the hierarchical extraction of high- and low-frequency components from time series can improve the ability to describe dynamic features. Simulations and experiments respectively demonstrate the predominance of HDLZC. The experimental results reveal that this method is significantly better than multiscale dispersive Lempel–Ziv complexity, hierarchical Lempel–Ziv complexity, multiscale dispersion entropy, and multiscale permutation entropy in extracting fault information.
Fault identification method of micro turbine blade based on the order spectral entropy of bearing vibration
Authors: Li Ning , Zhang Jingqi , Zhai Jingyu , Han Qingkai
Published: December 2022

In view of the difficulty in identifying the state of the micro turbine blade, this paper uses the order spectral entropy analysis method to extract the characteristic information of the blade fault based on the measured micro turbine bearing vibration data. Firstly, a micro-turbine test bench was established. The normal temperature stable inlet flow was produced by a blower, the high temperature and pressure unstable airflow was generated by turbojet combustion chamber, and the working inlet mode of a micro-turbine with a wide range of speed changes was simulated. The vibration signal of the bearing was collected by shell drilling, a variety of time-frequency domain feature analysis methods based on vibration signal are difficult to effectively identify blade faults under the combined action of unstable airflow and frequent variable speed. In this paper, the bearing vibration data in time domain is converted to the vibration data in angle domain, and then the order amplitude and entropy were compared and analyzed. The results show that the proposed method can effectively identify the blade fracture and fouling faults under the driving of stable and unstable airflow in the speed range of 0–20 000 r min−1. This method provides a new method for micro turbine blade condition monitoring through bearing vibration data.
Isomerism effects in relaxation dynamics of Au24(SR)16 thiolate-protected gold nanoclusters
Authors: Sun Yuanze , Yu Xueke , Liu Pengye , Han Wenhua , Xu Wen-wu , Su Yan , Zhao Jijun
Published: December 2022

Understanding the excited state behavior of isomeric structures of thiolate-protected gold nanoclusters is still a challenging task. In this paper, based on grand unified model and ring model for describing thiolate-protected gold nanoclusters, we have predicted four isomers of Au24(SR)16 nanoclusters. Density functional theory calculations show that the total energy of one of the predicted isomers is 0.1 eV lower in energy than previously crystallized isomer. The nonradiative relaxation dynamics simulations of Au24(SH)16 isomers are performed to reveal the effects of structural isomerism on relaxation process of the lowest energy states, in which that most of the low-excited states consist of core states. In addition, crystallized isomer possesses the shorter e–h recombination time, whereas the most stable isomer has the longer recombination time, which may be attributed to the synergistic effect of nonadiabatic coupling and decoherence time. Our results could provide practical guidance to predict new gold nanoclusters for future experimental synthesis, and stimulate the exploration of atomic structures of same sized gold nanoclusters for photovoltaic and optoelectronic devices.
Enhanced photonic spin Hall effect in Dirac semimetal metamaterial enabled by zero effective permittivity
Authors: Da Haixia , Song Qi , Hu Pengya , Ye Huapeng
Published: December 2022

With the recent discovery of three dimensional Dirac semimetals, their integrations with the optoelectronic devices allow the novel optical effects and functionalities. Here, we theoretically report the photonic spin Hall effect in a periodic structure, where three dimensional Dirac semimetals and the dielectric materials are assembled into the stack. The incident angle and frequency dependent spin shift spectrum reveals that the spin shifts of the transmitted wave in this structure emerge the obvious peaks and valleys for the horizontal polarized wave and their magnitudes and positions display a distinct dependence on the incident angle around the specific frequency. These observations originate from its zero value of the effective perpendicular permittivity and its greatly reduced transmission in the multilayered structure, whose mechanism is different from those in the previous works. Moreover, both the peaks and valleys of the transmitted spin shift are significantly sensitive to the Fermi energy of three dimensional Dirac semimetals, whose magnitudes and positions can be tuned by varying it. Our results highlight the vital role of three dimensional Dirac semimetals in their applications of the spin photonic devices and pave the way to explore the tunable photonic spin Hall effect by engineering their Fermi energies.
NuTracker: a coordinate-based neural network representation of lung motion for intrafraction tumor tracking with various surrogates in radiotherapy
Authors: Liu Cong , Wang Qingxin , Si Wen , Ni Xinye
Published: December 2022

Objective. Tracking tumors and surrounding tissues in real-time is critical for reducing errors and uncertainties during radiotherapy. Existing methods are either limited by the linear representation or scale poorly with the volume resolution. To address both issues, we propose a novel coordinate-based neural network representation of lung motion to predict the instantaneous 3D volume at arbitrary spatial resolution from various surrogates: patient surface, fiducial marker, and single kV projection. Approach. The proposed model, namely NuTracker, decomposes the 4DCT into a template volume and dense displacement fields (DDFs), and uses two coordinate neural networks to predict them from spatial coordinates and surrogate states. The predicted template is spatially warped with the predicted DDF to produce the deformed volume for a given surrogate state. The nonlinear coordinate networks enable representing complex motion at infinite resolution. The decomposition allows imposing different regularizations on the spatial and temporal domains. The meta-learning and multi-task learning are used to train NuTracker across patients and tasks, so that commonalities and differences can be exploited. NuTracker was evaluated on seven patients implanted with markers using a leave-one-phase-out procedure. Main results. The 3D marker localization error is 0.66 mm on average and <1 mm at 95th-percentile, which is about 26% and 32% improvement over the predominant linear methods. The tumor coverage and image quality are improved by 5.7% and 11% in terms of dice and PSNR. The difference in the localization error for different surrogates is small and is not statistically significant. Cross-population learning and multi-task learning contribute to performance. The model tolerates surrogate drift to a certain extent. Significance. NuTracker can provide accurate estimation for entire tumor volume based on various surrogates at infinite resolution. It is of great potential to apply the coordinate network to other imaging modalities, e.g. 4DCBCT and other tasks, e.g. 4D dose calculation.
Charge-plasma based symmetrical-gate complementary electron–hole bilayer TFET with improved performance for sub-0.5 V operation
Authors: Anam Aadil , Kumar Naveen , Amin S Intekhab , Prasad Dinesh , Anand Sunny
Published: December 2022

In this paper, the complementary charge-plasma (CP) based symmetrical-gate electron–hole bilayer (EHB) tunnel field-effect transistor (TFET) at a low operating voltage (⩽0.5 V) is introduced. Where, by using CP technique, the source/drain and EHB-channel is induced by depositing metal electrode with appropriate work function. Moreover, the immunity against random dopant fluctuations and the feasibility of a self-aligned process due to a symmetrical top/bottom gate arrangement without the need for a high thermal annealing process make the fabrication of the proposed EHB-TFET very reliable and efficient. Moreover, by implementing the density gradient quantum correction model, the quantum confinement and its effect on confining the 2D electron–hole concentration are also corrected as the proposed device has a smaller channel thickness of 5 nm. The proposed device shows superior performance against almost all Si-based CP-TFETs with a higher ON-current of 47.33 μA μm−1, a smaller average subthreshold swing of 13.53 mV dec−1 and a high ON-current to OFF-current ratio of 2.16 × 1013. This indicates that the proposed device is a promising candidate for future low-power applications.
Quench detection and early warning based on thermoelastic strain rate for HTS tapes thermally triggered by heat spots
Authors: Chen Jiaxiang , Guan Mingzhi , Tong Yujin , Wang Xingzhe , Zhou Youhe
Published: December 2022

The rapid detection and comprehensive monitoring of quench onset and evolution in high-temperature superconducting (HTS) materials remains immensely challenging because the normal zone propagation velocity in HTS materials is two or three orders of magnitude less than that in low-temperature superconductors. In this study, we experimentally and numerically explore quench events triggered by heat spots in yttrium barium copper oxide HTS tapes to characterize the quench onset and propagation. A multiplexed fiber Bragg grating sensor with multiple gratings was used to perform highly accurate strain measurements. Conventional voltage and temperature measurements were performed synchronously on the HTS tapes. A systematic comparison of these multifield signals during quench onset and development illustrated that the evolution of thermoelastic strain and strain-rate in HTS tapes captures the quench onset and propagation. A distinct feature was exhibited during the quenching of a pre-tensioned HTS tape: the thermoelastic strain initially relaxed but subsequently increased until the strain rate exhibited a significant slope change, which corresponded to the quench onset time. The thermoelastic strain in a nearly unconstrained HTS tape gradually increased until quenching occurred. A prominent characteristic for detecting quench onset in HTS materials have been revealed based on the change in the slope of the thermoelastic strain-rate or the second derivative of the strain remaining nearly constant. For a pre-tensioned HTS tape, the minimization of the thermoelastic strain or the strain-rate becoming zero may be a predictor that preceded the quench by ∼1–2 s, which can be, to a certain extent, regarded as an early warning. Another important and novel result was the experimental demonstration of global strain responses distant from the quench location in the pre-tensioned HTS tape, while the temperature and voltage detection are commonly localized methods. The mechanism behind these thermoelastic strain characteristics was further discussed and simulated from the induced Joule heating throughout the quench event. The measurements and numerical predictions suggested a new paradigm of quench detection based on the thermoelastic strain-rate in HTS materials.
Electronic properties of

α

-Mn-type non-centrosymmetric superconductor Re5.5Ta under hydrostatic pressure
Authors: Mariappan Sathiskumar , Bhoi Dilip , Krishnan Manikandan , Shoko Nagasaki , Vajeeston Ponniah , Arushi  , Kushwaha Roshan Kumar , Singh R P , Sonachalam Arumugam , Uwatoko Yoshiya
Published: December 2022

We have studied the effect of hydrostatic pressure on the superconducting and normal state properties of the non-centrosymmetric superconductor Re5.5Ta using magnetotransport, magnetization, and band structure studies. The superconducting transition temperature (

T

c

) reveals a modest decrease of ∼0.52 K as the external pressure is raised to 8 GPa. We found the Maki parameter,

α

M

>
1
,

both at ambient and high pressures, suggesting the significant role of the Pauli pair breaking effect. Furthermore, the lower critical field was found to decrease with a rate of −1.74 mT GPa−1 as pressure increases to 1.05 GPa. Analysis of the thermally activated flux flow region of

ρ

T
,
H

using the Arrhenius equation reveals the coexistence of single and collective vortex states. Further analysis of the critical current density indicates that the surface and volume pinning centers coexist and remain unaffected with varying pressure. Band structure calculations were performed using density functional theory and reveal a large bulk modulus,

B
0

∼ 289 GPa with

B
0
′

∼ 3.7, suggesting poor compressibility. In addition, we found that the density of states at the Fermi level barely reduces, even at pressures of up to 20 GPa. This is consistent with the experimental observation of robust superconductivity under compression.
Angular momentum and chaos bound of charged particles around Einstein–Euler–Heisenberg AdS black holes
Authors: Chen Deyou , Gao Chuanhong
Published: December 2022

In this paper, we investigate influences of the charge and angular momentum of a particle around a charged Einstein–Euler–Heisenberg AdS black hole on a Lyapunov exponent, and find spatial regions where the chaos bound is violated. Positions of circular orbits are gotten by fixing the charge and angular momentum of the particle, respectively. The positions gradually move away from the event horizon with the increase of the angular momentum when the charge is fixed and with the decrease of the charge when the angular momentum is fixed. For certain values of the charge, angular momentum and Euler–Heisenberg parameter, the spatial regions where the bound is violated are found. When the charge is fixed and the Euler–Heisenberg parameter is large, a small angular momentum causes the violation. Although the angular momentum is small, the corresponding spatial region is not small. An interesting discovery is that the bound is violated by the black hole when the particle’s charge is less than 1 andΛ=0, but this requires the black hole’s charge to be large enough. This violation may be related to the dynamical stability of the black hole. The backreaction of the particle on the background spacetime is not considered in the investigation.
Chiral SQUID-metamaterial waveguide for circuit-QED
Authors: Wang Xin , Lin Ya-Fen , Li Jia-Qi , Liu Wen-Xiao , Li Hong-Rong
Published: December 2022

Superconducting metamaterials, which are designed and fabricated with structured fundamental circuit elements, have motivated recent developments of exploring unconventional quantum phenomena in circuit quantum electrodynamics (circuit-QEDs). We propose a method to engineer 1D Josephson metamaterial as a chiral waveguide by considering a programmed spatiotemporal modulation on its effective impedance. The modulation currents are in the form of travelling waves which phase velocities are much slower than the propagation speed of microwave photons. Due to the Brillouin-scattering process, non-trivial spectrum regimes where photons can propagate unidirectionally emerge. Considering superconducting qubits coupling with this metamaterial waveguide, we analyze both Markovian and non-Markovian quantum dynamics, and find that superconducting qubits can dissipate photons unidirectionally. Moreover, we show that our proposal can be extended a cascaded quantum network with multiple nodes, where chiral photon transport between remote qubits can be realized. Our work might open the possibilities to exploit SQUID metamaterials for realizing unidirectional photon transport in circuit-QED platforms.
Resonance phenomena caused by mixed coupling in tristable systems
Authors: Ning Lijuan , Liu Tianpeng
Published: December 2022

Coupled systems have been widely encountered and have aroused much great interest in improving the response output of the system. Scholars pay more attention to the use of vibration resonance or stochastic resonance to amplify weak signals, but few examine the role of mixed coupling on the system response. The amplifying effect of mixed coupling on signal in tristable oscillators is studied in this paper. The spectral amplification factor, which is used to measure the amplification, shows a resonance peak with the coupling strength. The optimal coupling strength can be found to achieve the maximum output of the system. Moreover, the influence of the depth and position of the potential well on the response output is also analyzed. The results show that the properties of tristable oscillators can change the coupling threshold as well as improve amplification. We speculate that, in addition to the mixed coupling, the intrinsic mechanism of this behavior may be due to the different shapes of the tristable oscillators and their modes of variation. It provides new thoughts for amplifying and detecting weak signals in coupled systems.
Velocity correlations in jackdaw flocks in different ecological contexts
Authors: O’Coin Daniel , Mclvor Guillam E , Thornton Alex , Ouellette Nicholas T , Ling Hangjian
Published: December 2022

Velocity correlation is an important feature for animal groups performing collective motions. Previous studies have mostly focused on the velocity correlation in a single ecological context. It is unclear whether correlation characteristics vary in a single species in different contexts. Here, we studied the velocity correlations in jackdaw flocks in two different contexts: transit flocks where birds travel from one location to another, and mobbing flocks where birds respond to an external stimulus. We found that in both contexts, although the interaction rules are different, the velocity correlations remain scale-free, i.e. the correlation length (the distance over which the velocity of two individuals is similar) increases linearly with the group size. Furthermore, we found that the correlation length is independent of the group density for transit flocks, but increases with increasing group density in mobbing flocks. This result confirms a previous observation that birds obey topological interactions in transit flocks, but switch to metric interactions in mobbing flocks. Finally, in both contexts, the impact of group polarization on correlation length is not significant. Our results suggest that wild animals are always able to respond coherently to perturbations regardless of context.
Pulsed inductive CO2 laser with radio-frequency excitation and influence of the H2 content on the efficiency and lasing temporal characteristics
Authors: Razhev A M , Kargapol `tsev E S , Churkin D S , Trunov I A
Published: December 2022

In 2021, data on the effective pulsed gas discharge inductive CO2 laser with radio-frequency (RF) excitation were published with a pulse output energy of E∼ 1 J (the efficiency η∼ 14.5%) on the gas mixture He:N2:CO2 = 8:2:1. The efficiency of the developed CO2 laser had exceeded the value η∼ 21% at E∼ 350 mJ. At the beginning of 2022, it was shown that xenon addition (Xe = 4%) to the gas mixture made it possible to achieve an efficiency of η∼ 27% at an output energy of E∼ 600 mJ. For the first time, the effect of hydrogen additives in the active medium (He:N2:CO2:H2 and N2:CO2:H2 gas mixtures) was investigated for a pulsed inductive CO2 laser with RF excitation depending on the RF-pumping pulse duration value (τ), which allows the energy and temporal radiation characteristics of the laser to be controlled over a wider range. In addition to those already published, new experimental data have been obtained, namely the output beam profile of the inductive CO2 laser based on He:N2:CO2 = 8:2:1 gas mixture depending on the τ value. The new data will improve our understanding of inductive CO2 laser physics and of the plasma–chemical processes occurring in its active medium. RF current pulses propagated along inductor wires and, thus, an inductive discharge was formed to create a population inversion by IR transitions of CO2
* molecules.
Coexistence of giant Rashba spin splitting and quantum spin Hall effect in H–Pb–F
Authors: Xue Wenming , Li Jin , He Chaoyu , Ouyang Tao , Dai Xiongying , Zhong Jianxin
Published: December 2022

Rashba spin splitting (RSS) and quantum spin Hall effect (QSHE) have attracted enormous interest due to their great significance in the application of spintronics. In this work, we theoretically proposed a new two-dimensional (2D) material H–Pb–F with coexistence of giant RSS and quantum spin Hall effec by using the ab initio calculations. Our results show that H–Pb–F possesses giant RSS (1.21 eV⋅Å) and the RSS can be tuned up to 4.16 eV⋅Å by in-plane biaxial strain, which is a huge value among 2D materials. Furthermore, we also noticed that H–Pb–F is a 2D topological insulator (TI) duo to the strong spin–orbit coupling (SOC) interaction, and the large topological gap is up to 1.35 eV, which is large enough for for the observation of topological edge states at room temperature. The coexistence of giant RSS and quantum spin Hall effect greatly broadens the potential application of H–Pb–F in the field of spintronic devices.
Hydrogen evolution reaction between small-sized Zr
n
(n = 2–5) clusters and water based on density functional theory
Authors: Tang Lei-Lei , Shi Shun-Ping , Song Yong , Hu Jia-Bao , Diao Kai , Jiang Jing , Duan Zhan-Jiang , Chen De-Liang
Published: December 2022

Density functional theory (DFT) is used to calculate the most stable structures of Zr
n
(n = 2–5) clusters as well as the adsorption energy values of Zr
n
(n = 2–5) clusters after adsorbing single water molecule. The results reveal that there is a significant linear relationship between the adsorption energy values and the energy gaps of the Zr
n
(n = 2–5) clusters. Furthermore, the calculations of the reaction paths between Zr
n
(n = 2–5) and single water molecule show that water molecule can react with Zr
n
(n = 2–5) clusters to dissociate, producing hydrogen, and O atoms mix with the clusters to generate Zr
n
O (n = 2–5), all of which are exothermic reactions. According to the released energy, the Zr4 cluster is the most efficient in Zr
n
(n = 2–5) clusters reacting with single water molecule. The natural population analysis (NPA) and density of states (DOS) demonstrate the production of hydrogen and orbital properties in different energy ranges, respectively, jointly forecasting that Zr
n
O (n = 2–5) will probably continue to react with more water molecules. Our findings contribute to better understanding of Zr’s chemical reactivity, which can conduce to the development of effective Zr-based catalysts and hydrogen-production methods.
Infrared optical absorption of Fröhlich polarons in metal halide perovskites
Authors: Cui Yu , Liu Xiao-Yi , Ma Xu-Fei , Deng Jia-Pei , Liu Yi-Yan , Wang Zi-Wu
Published: December 2022

The formation of Fröhlich polarons in metal halide perovskites, arising from the charge carrier–longitudinal optical (LO) phonon coupling, has been proposed to explain their exceptional properties, but the effective identification of polarons in these materials is still a challenging task. Herein, we theoretically present the infrared optical absorption of Fröhlich polarons based on the Huang–Rhys model. We find that multiphonon overtones appear as the energy of the incident photons matches the multiple LO phonons, wherein the average phonon number of a polaron can be directly evaluated by the order of the strongest overtone. These multiphonon structures sensitively depend on the scale of electronic distribution in the ground state and the dimensionality of the perovskite materials, revealing the effective modulation of competing processes between polaron formation and carrier cooling. Moreover, the order of the strongest overtone shifts to higher ones with temperature, providing a potential proof that the carrier mobility is affected by LO phonon scattering. The present model not only suggests a direct way to verify Fröhlich polarons but also enriches our understanding of the properties of polarons in metal halide perovskites.
Synthesis, magnetic and electromagnetic wave absorption properties of planar anisotrop Y2Co17@SiO2 rare earth soft magnetic composites
Authors: Qiao Liang , Tu Cheng-Fa , Wu Wei , Wang Wen-Biao , Yang Sheng-Yu , Zhe Sun , Wu Peng , Yang Jin-Bo , Wang Chang-Sheng , Wang Tao , Li Fa-Shen
Published: December 2022

Intermetallic complexes of rare-earth and 3d transition metals with core-shell structures are commonly employed as microwave absorbing materials due to their high saturation magnetizations and natural resonance in GHz. Hence, we synthesized Y2Co17 alloy via the co-precipitation reduction-diffusion technique, then coated the Y2Co17 magnetic powders with SiO2 to create Y2Co17@SiO2 core-shell structures. The formation of Y2Co17@SiO2/polyurethane (PU) at various volume fractions and their magnetic, electromagnetic properties were investigated using x-ray diffraction, scanning electron microscopy, energy dispersive spectroscopy, and vector network analyzer. The microwave absorption characteristics of Y2Co17@SiO2/PU were also investigated at various volume fractions. We not only investigate the zero-reflection conditions of the samples with different volume fractions, but also show that every absorber has a strong reflection loss value (RL ≤ −65.00 dB) and excellent microwave absorption properties with an average RL of Y2Co17@SiO2/PU being below −10 dB at 8 GHz–18 GHz under different thicknesses, showing that the enhancement of microwave absorption performance arises from the balance between permeability and permittivity of absorber.
Variational quantum simulation of thermal statistical states on a superconducting quantum processer
Authors: Guo Xue-Yi , Li Shang-Shu , Xiao Xiao , Xiang Zhong-Cheng , Ge Zi-Yong , Li He-Kang , Song Peng-Tao , Peng Yi , Wang Zhan , Xu Kai , Zhang Pan , Wang Lei , Zheng Dong-Ning , Fan Heng
Published: December 2022

Quantum computers promise to solve finite-temperature properties of quantum many-body systems, which is generally challenging for classical computers due to high computational complexities. Here, we report experimental preparations of Gibbs states and excited states of Heisenberg XX and XXZ models by using a 5-qubit programmable superconducting processor. In the experiments, we apply a hybrid quantum–classical algorithm to generate finite temperature states with classical probability models and variational quantum circuits. We reveal that the Hamiltonians can be fully diagonalized with optimized quantum circuits, which enable us to prepare excited states at arbitrary energy density. We demonstrate that the approach has a self-verifying feature and can estimate fundamental thermal observables with a small statistical error. Based on numerical results, we further show that the time complexity of our approach scales polynomially in the number of qubits, revealing its potential in solving large-scale problems.
Analysis of the neural mechanism of spectra decrease in MCI by a thalamo-cortical coupled neural mass model
Authors: Cui Dong , Li Han , Liu Pengxiang , Gu Guanghua , Li Xiaoli , Wang Lei , Yin Shimin
Published: December 2022

Objective. In order to deeply understand the neurophysiological mechanism of the spectra decrease in mild cognitive impairment (MCI), this paper studies a new neural mass model, which can simulate various intracerebral electrophysiological activities. Approach. In this study, a thalamo-cortical coupled neural mass model (TCC-NMM) is proposed. The influences of the coupling coefficients and other key parameters on the model spectra are simulated. Then, the unscented Kalman filter (UKF) algorithm is used to reversely identify the parameters in the TCC-NMM. Furthermore, the TCC-NMM and UKF are combined to analyze the spectra reduction mechanism of electroencephalogram (EEG) signals in MCI patients. The independent sample t-test is carried out to statistical analyze the differences of the identified parameters between MCI and normal controls. The Pearson correlation analysis is used to analyze the intrinsic relationship between parameters and the scores of the comprehensive competence assessment scale. Main results. The simulation results show that the decreased cortical synaptic connectivity constants C
1 can result in spectra decrease of the TCC-NMM outputs. The real EEG analysis results show that the identified values of parameter C
1 are significant lower in the MCI group than in control group in frontal and occipital areas and the parameters C
1 are positively correlated with the Montreal Cognitive Assessment (MoCA) scores in the two areas. This consistency suggests that the cortical synaptic connectivity loss from pyramidal cells to excitatory interneurons (eIN) may be one of the neural mechanisms of EEG spectra decrease in MCI. Significance. (a) In this study, a new mathematical model TCCNMM based on anatomy and neurophysiology is proposed. (b) All key parameters in TCC-NMM are studied in detail through the forward and reverse analysis and the influence of these parameters on the output spectra of the model is pointed out. (c) The possible neural mechanism of the decreased spectra in MCI patients is pointed out by the joint analysis of simulation in forward with TCC-NMM and analysis of the actual EEG signals in reverse with UKF identification algorithm. (d) We find that the identified parameter C1 of MCI patients is significantly lower than that of the control group, which is consistent with the simulation analysis of TCC-NMM. So, we suggest that the decreased MCI alpha power spectrum is likely related to the cortical synaptic connection loss from pyramidal cells to eIN.
Identification and classification of epileptic EEG signals using invertible constant-Q transform-based deep convolutional neural network
Authors: Eltrass Ahmed S , Tayel Mazhar B , EL-qady Ahmed F
Published: December 2022

Context. Epilepsy is the most widespread disorder of the nervous system, affecting humans of all ages and races. The most common diagnostic test in epilepsy is the electroencephalography (EEG). Objective. In this paper, a novel automated deep learning approach based on integrating a pre-trained convolutional neural network (CNN) structure, called AlexNet, with the constant-Q non-stationary Gabor transform (CQ-NSGT) algorithm is proposed for classifying seizure versus seizure-free EEG records. Approach. The CQ-NSGT method is introduced to transform the input 1D EEG signal into 2D spectrogram which is sent to the AlexNet CNN model. The AlexNet architecture is utilized to capture the discriminating features of the 2D image corresponding to each EEG signal in order to distinguish seizure and non-seizure subjects using multi-layer perceptron algorithm. Main results. The robustness of the introduced CQ-NSGT technique in transforming the 1D EEG signals into 2D spectrograms is assessed by comparing its classification results with the continuous wavelet transform method, and the results elucidate the high performance of the CQ-NSGT technique. The suggested epileptic seizure classification framework is investigated with clinical EEG data acquired from the Bonn University database, and the experimental results reveal the superior performance of the proposed framework over other state-of-the-art approaches with an accuracy of 99.56%, sensitivity of 99.12%, specificity of 99.67%, and precision of 98.69%. Significance. This elucidates the importance of the proposed automated system in helping neurologists to accurately interpret and classify epileptic EEG records without necessitating tedious visual inspection or massive data analysis for long-term EEG signals.
Drugless nanoparticles tune-up an array of intertwined pathways contributing to immune checkpoint signaling and metabolic reprogramming in triple-negative breast cancer
Authors: Ramzy Asmaa , ElSafy Sara , Elshoky Hisham A , Soliman Aya , Youness Rana , Mansour Samar , Sebak Aya
Published: December 2022

Metabolic reprogramming ‘Warburg effect’ and immune checkpoint signaling are immunosuppressive hallmarks of triple-negative breast cancer (TNBC) contributing to the limited clinical applicability of immunotherapy. Biomaterials arise as novel tools for immunomodulation of the tumor microenvironment that can be used alongside conventional immunotherapeutics. Chitosan and lecithin are examples of versatile biomaterials with interesting immunomodulatory properties. In this study, we aimed at investigation of the role of carefully designed hybrid nanoparticles (NPs) on common mediators of both programmed death ligand 1 (PD-L1) expression and glycolytic metabolism. Hybrid lecithin–chitosan NPs were prepared and characterized. Their intracellular concentration, localization and effect on the viability of MDA-MB-231 cells were assessed. Glycolytic metabolism was quantified by measuring glucose consumption, adenosine triphosphate (ATP) generation, lactate production and extracellular acidification. Nitric oxide production was quantified using Greiss reagent. Gene expression of inducible nitric oxide synthase (iNOS), phosphatidylinositol-3-kinase (PI3K), protein kinase B (PKB or Akt), mammalian target of rapamycin (mTOR), hypoxia-inducible factor 1α (HIF-1α) and PD-L1 was quantified by quantitative reverse transcription polymerase chain reaction (q-RT-PCR). Chitosan, lecithin and the NPs-formulated forms have been shown to influence the ‘Warburg effect’ and immune checkpoint signaling of TNBC cells differently. The composition of the hybrid systems dictated their subcellular localization and hence the positive or negative impact on the immunosuppressive characteristics of TNBC cells. Carefully engineered hybrid lecithin–chitosan NPs could convert the immune-suppressive microenvironment of TNBC to an immune-active microenvironment via reduction of PD-L1 expression and reversal of the Warburg effect.
Energy and food security implications of transitioning synthetic nitrogen fertilizers to net-zero emissions
Authors: Rosa Lorenzo , Gabrielli Paolo
Published: December 2022

By synthetically producing nitrogen fertilizers from ammonia (NH3), the Haber–Bosch process has been feeding humanity for more than one hundred years. However, current NH3 production relies on fossil fuels, and is energy and carbon intensive. This commits humanity to emissions levels not compatible with climate goals and commits agricultural production to fossil fuels dependency. Here, we quantify food and energy implications of transitioning nitrogen fertilizers to net-zero CO2 emissions. We find that 1.07 billion people are fed from food produced from imported nitrogen fertilizers. An additional 710 million people are fed from imported natural gas feedstocks used for fertilizers production, meaning that 1.78 billion people per year are fed from imports of either fertilizers or natural gas. These findings highlight the reliance of global food production on trading and fossil fuels, hence its vulnerability to supply and energy shocks. However, alternative routes to achieve net-zero emissions in NH3 production exist, which are based on carbon capture and storage, electrification, and biomass. These routes comply with climate targets while mitigating the risks associated with food security. Yet, they require more land, energy, and water than business-as-usual production, exacerbating land and water scarcity and the use of limited natural resources. Transitioning fertilizers to net-zero emissions can contribute to climate and food security goals, although water, land, and energy trade-offs should be considered.
The single-point Berry phase in condensed-matter physics
Authors: Resta Raffaele
Published: December 2022

The Berry phase plays an outstanding role in condensed-matter physics, where it provides the main entry for defining and computing a key observable: macroscopic electrical polarization. This phase obtains as a loop integral in reciprocal space, which has the topology of a torus. I show here that in some circumstances the loop may be contracted to a point, and polarization can be computed in practice from a single Hamiltonian diagonalization.