bluuebunny/crossref_metadata_2025_split huggingface dataset:
Quantitative characterization of the temporal-spatial evolution of RONS in air surface micro-discharge using UV–VIS optical absorption spectroscopic diagnosis and modeling approach
Authors: Liu Chen , Feng Chunlei , Wang Zhiwei , Wu Ding , Ding Hongbin 
Published: May 2023

Abstract
The research of the chemically active species of cold atmospheric pressure plasmas is a essential step for a more in-depth comprehension of the effects of its interaction with the target. In this paper, the temporal and spatial evolution of key species O3, NO2 and NO3 produced by surface micro-discharge in air were investigated. UV–VIS optical absorption spectroscopy at 254 nm, 400 nm and 662 nm were used to measure the concentrations of O3, NO2 and NO3, respectively. The results show that the temporal evolution of O3, NO2 and NO3 are revealed a significant correlation with the surface power density (SPD). The phenomenon of O3 and NO3 quenching occur once the SPD overcomes a critical value of 0.15 W cm−2. An O3-enriched atmosphere (peak concentration around 3000 ppm) is formed when the SPD is below the critical value, and a NO2-enriched atmosphere (maximum NO2 density around 600 ppm) is formed at higher SPD. In addition, the concentration distribution of O3, NO2 and NO3 in the chamber ranging from 10–100 mm of the downstream of the mesh electrode tends to be uniform. Finally, a zero-dimensional model of the afterglow chemistry, validated using the experimental measurements, is developed to determined important reactions affecting O3, NO2 and NO3 respectively, and obtain insight into the evolutionary behavior of the considered reactive species.
Transport properties of a 1000 nm HgTe film: the interplay of surface and bulk carriers
Authors: Savchenko M L , Kozlov D A , Vasilev N N , Mikhailov N N , Dvoretsky S A , Kvon Z D 
Published: May 2023

AbstractWe report on systematic study of transport properties of a 1000 nm HgTe film. Unlike thinner and strained HgTe films, which are known as high-quality three-dimensional topological insulators, the film under study is much thicker than the limit of pseudomorphic growth of HgTe on a CdTe substrate. Therefore, the 1000 nm HgTe film is expected to be fully relaxed and has the band structure of bulk HgTe, i.e. a zero gap semiconductor. Additionally, the system is characterized by the bands inversion, so that the two-dimensional topological surface states (TSSs) are expected to exist. To check this claim we studied classical and quantum transport response of the system. We demonstrate that by tuning the top-gate voltage one can change the electron-dominating transport to the hole one. The highest electron mobility is found to be more than300×103 cm2 Vs−1. The system exhibits Shubnikov-de Haas (SdH) oscillations with a complicated pattern and shows up to five independent frequencies in corresponding Fourier spectra. These Fourier peaks are attributed to the TSSs, Volkov-Pankratov states and spin-degenerate bulk states in the accumulation layer near the gate. The observed peculiarities of the quantum transport are the strong SdH oscillations of the Hall resistance, and the suppressed oscillatory response of the TSSs.
Relativistic effects of LEO satellite and its impact on clock prediction
Authors: Wu Meifang , Wang Kan , Liu Jiawei , Zhu Yuncong 
Published: May 2023

Abstract
Low Earth orbit (LEO) augmentation in the global navigation satellite system has become a focus in the current satellite navigation field. To achieve high precision in positioning, navigation and timing services, relativistic effects should be considered, as they are difficult to distinguish from LEO satellite clock estimates and disturb their predictions. The relativistic effects on LEO satellite clocks are discussed in detail based on both theoretical and empirical results. Two LEO satellite clock prediction strategies are proposed, with and without removing the relativistic effect, using real data from typical LEO satellites: SENTINEL-3B and Gravity Recovery and Climate Experiment Follow-On (GRACE FO-1). For GRACE FO-1 and SENTINEL-3B, the relativistic effects are both on the order of nanoseconds and after removing the relativistic effects, the modified Allan deviations of the clocks are shown to be significantly improved. Based on the prediction strategies proposed, for SENTINEL-3B at around 810 km, with the prediction period increased from 30 to 3600 s, the root mean square error (RMSE) increases from 0.025 ns to about 1.4–1.6 ns. For the lower LEO satellite GRACE FO-1 at around 500 km, the RMSE of the predicted clocks increases more rapidly, i.e. from 0.012 ns at 30 s to about 4.5 ns at 3600 s. Results showed that the LEO satellite relativistic effects developed based on the theory could correct the majority, but not all of the once- and twice-per-revolution terms in the LEO satellite clocks. Although the corrections have exhibited effective improvements in the clock stability, they do not behave better than simply applying the mathematical model to the clock predictions. The latter model, however, does not have physical foundations as the former one.
Demonstrating the electron blocking effect of AlGaN/GaN superlattice cladding layers in GaN-based laser diodes
Authors: Li Shukun , Lei Menglai , Lang Rui , Yu Guo , Chen Huanqing , Wen Peijun , Khan Muhammad Saddique Akbar , Meng Linghai , Zong Hua , Jiang Shengxiang , Hu Xiaodong 
Published: May 2023

Abstract
Electron leakage currents seriously limit the power conversion efficiencies (PCEs) of gallium nitride (GaN)-based laser diodes (LDs). To minimize the leakage currents, electron blocking layers are generally applied in the p-type region. However, few works have discussed the electron blocking effect of a p-cladding layer, which is found to be critical in suppressing the leakage currents of an LD. In this work, we compare the blocking performance of uniform AlGaN p-cladding layers and AlGaN/GaN superlattice (SL) p-cladding layers with the same average Al component respectively. Both light-emitting diodes (LEDs) and LDs with the same epitaxy structures are characterized by light–current (L–I) and current–voltage (I–V) measurements. The latest analytical model of leakage currents is applied to fit the L–I curves of LEDs, where smaller leakage coefficients are observed in the SL structures compared with the uniform-layer structures. Eighty LDs with varying ridge widths are studied by comparing the threshold current densities, slope efficiencies, and PCEs. The SL-based p-cladding layer shows statistically significant advantages over a uniform AlGaN layer. The blocking effects of both scattering- and bound-state electrons in SLs are investigated theoretically. Repetitive reflection and thermal relaxation are responsible for the blocking effect of scattering-state electrons. Simulation results indicate that the tunneling effect of bound-state electrons through a miniband mechanism is insignificant at a large injection level due to a negative differential conductivity by the Esaki–Tsu effect. We demonstrate a better electron blocking performance of p-cladding layers based on SLs than uniform AlGaN layers in GaN-based LDs.
Ligand field luminescence in the honeycomb Mott insulator α-RuCl3
Authors: Mandal Shoubhik , Banerjee Abhishek , Ganesan R , Kumar P S Anil 
Published: May 2023

Abstract
Novel electronic structure is central to Kitaev-like quantum spin liquid ground state in the van der Waals antiferromagnet α-RuCl3. In this octahedral low-spin

4

d
5

system, the rich bandstructure includes Mott–Hubbard insulating bandgap of ∼1.1 eV and ligand field induced gap of ∼2 eV. Though the bandgap is extensively reported in previous optical and photoemission studies, the latter gap is less understood. In this regard, we probed the ligand field-induced electronic structure of bulk α-RuCl3 single crystals via unpolarized photoluminescence (PL) spectroscopy under linearly polarized excitation in the visible region. We observed the broad principal PL peak at E
PL

≈

1.87 eV, close to the energy required for the optical transition across the ligand field splitting gap (∼2 eV). This gap (E
PL) monotonically increases with temperature, described by the thermal expansion of lattice parameters dominating the electron–phonon interaction in this Honeycomb Mott insulator. Moreover, we observed the multiplet structure of the PL spectra, which can be explained by parity-forbidden d–d transitions in the light of single ion ligand-field theory. We attribute the broad PL linewidths to strong vibronic coupling modeled by the Huang–Rhys parameter. Further we observed the signature of structural transitions, indicated by thermal hysteresis in normalized integrated PL intensity.
Electronic properties of EuO and Eu2O3: FP-LAPW and LCAO computations and Compton spectroscopy strategies
Authors: Meena Lekhraj , Meena Seema K , Ahuja Ushma , Heda N L , Ahuja B L 
Published: May 2023

Abstract
Spin projected energy bands and density of states (DOS) have been deduced using full potential linearized augmented plane wave (FP-LAPW) with density functional theory (DFT) to analyze the electronic properties of EuO and Eu2O3. Whereas the Mulliken population (MP) and Compton profiles (CPs) for both the compounds have been computed using linear combination of atomic orbitals (LCAO) with pure and hybrid DFT (WC1LYP) schemes. The MP analysis indicates EuO to be more covalent than Eu2O3. Our first ever CP measurements for Eu2O3 (using 20 Ci 137Cs Compton spectrometer) indicate DFT with generalized gradient approximation and WC1LYP as successful prescriptions for predicting the electronic properties of such rare-Earth oxides. In addition, equally normalized experimental CPs of Eu2O3 are compared with other rare-Earth oxides RE2O3 (RE = Nd, Sm, Er and Yb) to decide an overall trend of localisation of f-electrons. A metallic behaviour of Eu2O3 is observed on the basis of real-space analysis of experimental, LCAO and free electron theory based CPs of Eu2O3.
Morphology, structural properties, impedance spectroscopy, AC conductivity, and dielectric relaxation properties of boron subphthalocyanine chloride amorphous films
Authors: Darwish A A A , Qashou Saleem I , El-Zaidia E F M , El-Rahman K F Abd , Hamdalla Taymour A , Al-Ghamdi S A , Alsharari Abdulrhman M , Khasim Syed , Alzahrani Ahmed Obaid M , Yahia I S 
Published: May 2023

Abstract
Through the use of thermal evaporation, boron subphthalocyanine chloride (B-subPcCl) films were created. X-ray diffraction pattern reveals that the B-subPcCl is characterized by amorphous nature, while atomic force microscopy images show that the surface topography of B-subPcCl is composed of homogeneous elliptical nanoparticles with grain size and roughness of 90 and 70 nm, respectively. The impedance measurements of B-subPcCl film at the temperature ranges of 298–398 K were studied and were fitted to the analog of a Rp//CPE equivalent electrical circuit model. The relationship between AC conductivity and frequency at different temperatures demonstrated that the correlated barrier hopping (CBH) model dominates the transport charge mechanism between the closest sites. The DC conductivity parameters were calculated, and they were compared with the relative organic compounds. The dependence of the dielectric constant (ε
1) and the dielectric loss (ε
1) on frequency showed a significant decrease of ε
1 and ε
2 values as the frequency increased. At different temperatures, the variation of the imaginary modulus (M
2) of B-subPcCl with frequency showed a relaxation process with an activation energy of 0.066 eV.
Theoretical analysis of a mid-infrared Kerr frequency comb in a graphene-on-silicon micro-resonator
Authors: Chen Weicheng , He Qi , Guo Rongxiang , Wan Dian , Han Qun , Hu Haofeng , Wang Jiaqi , Zou Yi , Xiao Ting-Hui , Liu Tiegen , Cheng Zhenzhou 
Published: May 2023

Abstract
Mid-infrared (Mid-IR) Kerr frequency combs have great application potential in sensing and spectroscopy. To generate a Kerr frequency comb, a continuous-wave, wavelength-tunable, narrow-linewidth, low-noise laser is normally utilized to pump a high-nonlinearity micro-resonator to emit a large number of coherent and equally spaced modes. However, chip-based pump lasers in the mid-IR band, namely, quantum cascade lasers and interband cascade lasers, are usually challenging to develop with both high output powers and good wavelength tunability based on a single diode. To overcome the limitation, we theoretically study a mid-IR Kerr frequency comb generation technique based on a graphene-on-silicon micro-resonator by using a monochromatic mid-IR laser. The approach is based on the exploration of an electric-field-assisted resonance scanning technique and graphene-enhanced silicon Kerr nonlinearity. Our result shows that a soliton Kerr frequency comb with a spectral range of 3.23–5.26 μm, 3-dB bandwidth of ∼550 nm, and frequency spacing of 140 GHz could be generated under a pump wavelength of 4 μm. The study paves a promising way toward developing monolithically chip-integrated mid-IR Kerr frequency combs with cost efficiencies and ultrafast tuning speeds.
Dark matter axions in the early universe with a period of increasing temperature
Authors: Arias Paola , Bernal Nicolás , Osiński Jacek K. , Roszkowski Leszek 
Published: May 2023

Abstract
We consider the production of axion dark matter through the misalignment mechanism in the context of a nonstandard cosmological history involving early matter domination by a scalar field with a time-dependent decay rate. In cases where the temperature of the Universe experiences a temporary period of increase, Hubble friction can be restored in the evolution of the axion field, resulting in the possibility of up to three “crossings” of the axion mass and the Hubble expansion rate.
This has the effect of dynamically resetting the misalignment mechanism to a new initial state for a second distinct phase of oscillation.
The resultant axion mass required for the present dark matter relic density is never bigger than the standard-history window and can be smaller by more than three orders of magnitude, which can be probed by upcoming experiments such as ABRACADABRA, KLASH, ADMX, MADMAX, and ORGAN, targeting the axion-photon coupling. This highlights the possibility of exploring the cosmological history prior to Big Bang Nucleosynthesis through searches for axion dark matter beyond the standard window.
Searching for photon-ALPs mixing effects in AGN gamma-ray energy spectra
Authors: Yu Qixin , Horns Dieter 
Published: May 2023

Abstract
High energy gamma-rays propagating in external magnetic fields may convert into axion-like particles (ALPs). In this case, the observed gamma-ray spectra are modified
by the resulting energy-dependent conversion probability.
In this study, we use the energy spectra of 20 extra-galactic gamma-ray sources recorded during 10 years of Fermi-LAT observations.
We define a test statistics based upon the likelihood ratio to test the hypothesis for a spectral model without vs. a model
with photon-ALPs coupling. The conversion probability is calculated for fixed values of the mass and two-photon coupling of the pseudo-scalar
particle while the external magnetic field is characterized by the additional free parameters length scale s and average field strength B.
As a consistency check and in order to extend the analysis to include very high energy gamma-ray data, another test statistics is defined
with the χ2 method.
We find for 18 of the 20 sources a favorable fit, particularly for Markarian 421 and NGC 1275 a significant improvement, with the hypothesis of photon-ALPs coupling in likelihood analysis. The
test statistics of the sources are combined and the significance has been estimated 5.3σ (test statistics summed in local maxima of all sources) and 6.0σ (global maxima). The significance is estimated from dedicated simulations under the null hypotheses. The locally best-fitting values of B and s fall into the range that is
expected for large scale magnetic fields present in relevant astrophysical environments.
Testing gravity with gravitational wave friction and gravitational slip
Authors: Matos Isabela S. , Bellini Emilio , Calvão Maurício O. , Kunz Martin 
Published: May 2023

Abstract
Gravitational waves (GWs) emitted by binary sources are interesting signals for testing gravity on cosmological scales since they allow measurements of the luminosity distance. When followed by electromagnetic counterparts, in particular, they enable a reconstruction of the GW-distance-redshift relation. In the context of several modified gravity (MG) theories, even when requiring that the speed of propagation is equal to that of light, this GW distance differs from the standard electromagnetic luminosity distance due to the presence of a modified friction in the GW propagation. The very same source of this friction, which is the running of an effective Planck mass, also affects the scalar sector generating gravitational slip, i.e. a difference between the scalar potentials, an observable that can be inferred from large-scale structure (LSS) probes. In this work, we use a model within effective field theories for dark energy to exemplify precisely the fact that, at the linear perturbation level, parametrizing a single function is already enough to generate simultaneous deviations in the GW distance and the slip. By simulating multimessenger GW events that might be detected by the Einstein Telescope in the future, we compare the constraining power of the two observables on this single degree of freedom. We then combine forecasts of an Euclid-like survey with GW simulations, coming to the conclusion that, when using Planck data to better constrain the cosmological parameters, those future data on the scalar and tensor sectors are competitive to probe such deviations from General Relativity, with LSS giving stronger (but more model-dependent) results than GWs.
Astrophysical observables for regular black holes with sub-Planckian curvature*
Authors: Zeng Wei , Ling Yi , Jiang Qing-Quan 
Published: May 2023

Abstract
We investigate the photon sphere and marginally stable circular orbit of massive particles over the recently proposed regular black holes with sub-Planckian curvature and a Minkowskian core. We derive the effective potential for geodesic orbits and determine the radius of circular photon orbits, with an analysis of the stability of these orbits. We extend our analysis to the background of a compact massive object (CMO) without a horizon, whose mass is below the lowest bound for the formation of a black hole. For massive particles, marginally stable circular orbits become double-valued in the CMO phase. Through a comparison with Bardeen and Hayward black holes, we also find that the locations of the photon sphere and marginally stable circular orbit in the CMO phase with a Minkowskian core are evidently different from those in the CMO phase with a dS core, which potentially provides a way to distinguish between these two types of black holes by astronomical observation. Finally, we present the observational constraint on the deviation parameter for such regular black holes using observed data from the black hole M87*.
Cleaning Radio Frequency Interference in Pulsar-Folded Data Based on the Conditional Random Fields with an Adaptive Prior
Authors: Chen Xue , Han J. L. , Su W. Q. , Yang Z. L. , Zhou D. J. 
Published: May 2023

Abstract
Radio astronomy observations are frequently impacted by radio frequency interference (RFI). We propose a novel method, named 2σCRF, for cleaning RFI in the folded data of pulsar observations, utilizing a Bayesian-based model called conditional random fields (CRFs). This algorithm minimizes the “energy” of every pixel given an initial label. The standard deviations (i.e., rms values) of the folded pulsar data are utilized as pixels for all subintegrations and channels. Non-RFI data without obvious interference is treated as “background noise,” while RFI-affected data have different classes due to their exceptional rms values. This initial labeling can be automated and is adaptive to the actual data. The CRF algorithm optimizes the label category for each pixel of the image with the prior initial labels. We demonstrate the efficacy of the proposed method on pulsar folded data obtained from Five-hundred-meter Aperture Spherical radio Telescope observations. It can effectively recognize and tag various categories of RFIs, including broadband or narrowband, constant or instantaneous, and even weak RFIs that are unrecognizable in some pixels but picked out based on their neighborhoods. The results are comparable to those obtained via manual labeling but without the need for human intervention, saving time and effort.
Velocity Dispersion σ
aper Aperture Corrections as a Function of Galaxy Properties from Integral-field Stellar Kinematics of 10,000 MaNGA Galaxies
Authors: Zhu Kai , Li Ran , Cao Xiaoyue , Lu Shengdong , Cappellari Michele , Mao Shude 
Published: May 2023

Abstract
The second moment of the stellar velocity within the effective radius, denoted by

σ

e

2

, is a crucial quantity in galaxy studies, as it provides insight into galaxy properties and their mass distributions. However, large spectroscopic surveys typically do not measure σ
e directly, instead providing σ
aper, the second moment of the stellar velocity within a fixed fiber aperture. In this paper, we derive an empirical aperture correction formula, given by

σ

aper

/

σ

e

=

(

R

aper

/

R

e

)

α

, using spatially resolved stellar kinematics extracted from approximately 10,000 Sloan Digital Sky Survey–Mapping Nearby Galaxies at Apache Point Observatory integral field unit observations. Our analysis reveals a strong dependence of α on the r-band absolute magnitude M
r, g–i color, and Sérsic index n
Ser, where α values are lower for brighter, redder galaxies with higher Sérsic indices. Our results demonstrate that the aperture correction derived from previous literature on early-type galaxies cannot be applied to predict the aperture corrections for galaxies with intermediate Sérsic indices. We provide a lookup table of α values for different galaxy types, with parameters in the ranges of −18 > M
r > −24, 0.4 < g–i < 1.6, and 0 < n
Ser < 8. A Python script is provided to obtain the correction factors from the lookup table.
Variability of Young Stellar Objects in the Perseus Molecular Cloud
Authors: Wang Xiao-Long , Fang Min , Herczeg Gregory J. , Gao Yu , Tian Hai-Jun , Zhou Xing-Yu , Zhang Hong-Xin , Chen Xue-Peng 
Published: May 2023

Abstract
We present an analysis of 288 young stellar objects (YSOs) in the Perseus molecular cloud that have well defined g and r-band lightcurves from the Zwicky Transient Facility. Of the 288 YSOs, 238 sources (83% of our working sample) are identified as variables based on the normalized peak-to-peak variability metric, with variability fraction of 92% for stars with disks and 77% for the diskless populations. These variables are classified into different categories using the quasiperiodicity (Q) and flux asymmetry (M) metrics. Fifty-three variables are classified as strictly periodic objects that are well phased and can be attributed to spot modulated stellar rotation. We also identify 22 bursters and 25 dippers, which can be attributed to accretion burst and variable extinction, respectively. YSOs with disks tend to have asymmetric and non-repeatable lightcurves, while the YSOs without disks tend to have (quasi)periodic lightcurves. The periodic variables have the steepest change in g versus g − r, while bursters have much flatter changes than dippers in g versus g − r. Periodic and quasiperiodic variables display the lowest variability amplitude. Simple models suggest that the variability amplitudes of periodic variables correspond to changes of the spot coverage of 30%–40%, burster variables are attributed to accretion luminosity changes in the range of L
acc/L
⋆ = 0.1–0.3, and dippers are due to variable extinction with A

V
changes in the range of 0.5–1.3 mag.