bluuebunny/crossref_metadata_2025_split huggingface dataset:
Electronic structures of metal/H-diamond (111) interfaces by ab-initio studies
Authors: Xu Erqi , Xie Zhiyang , Cheng Chunmin , He Xiaofei , Shen Wei , Wu Gai , Liang Kang , Guo Yuzheng , Ju Guangxu , Cao Ruyue , Zhang Zhaofu 
Published: May 2024

Abstract
With ultra-wide bandgap and outstanding thermal properties, diamond-based high-power devices have excellent application prospects. The crystal structure and electronic property of the metal/hydrogen-terminated diamond (H-diamond) interfaces have been extensively studied experimentally, but the Schottky barrier height (SBH) theory at the metal/H-diamond interface has not been systematically investigated yet. In this work, SBHs of interfaces formed by H-diamond (111) surfaces with 12 metals (Y, Sc, Mg, Ag, Al, Ti, Cu, Co, Pd, Ni, Au and Pt) are investigated using ab-initio calculations. The fitted curve of the SBH with respect to the metal work function is obtained with a Fermi pinning factor of 0.30, which is close to the empirical value of 0.36. Due to the negative electron affinity of H-diamond, Schottky contacts can be formed with low work function metals, which is useful in device design to regulate the SBH and it is relatively easier to form ohmic contacts with high work function metals, leading to low contact resistances. Our work sheds light on the rational design of diamond-based semiconductor devices with low contact resistances.
Disorder induced band gap lowering in kesterite type Cu2ZnSnSe4 and Ag2ZnSnSe4: a first-principles and special quasirandom structures investigation
Authors: Fritsch Daniel , Schorr Susan 
Published: May 2024

Abstract
Quaternary chalcogenides, i.e. Cu2ZnSnS4, crystallising in the kesterite crystal structure have already been demonstrated as potential building blocks of thin film solar cells, containing only abundant elements and exhibiting power conversion efficiencies of about 14.9% so far. However, due to the potential presence of several structurally similar polymorphs, the unequivocal identification of their ground state crystal structures required the application of more elaborate neutron diffraction experiments. One particular complication arose from the later identified Cu–Zn disorder, present in virtually all thin film samples. Subsequently, it has been shown experimentally that this unavoidable Cu–Zn disorder leads to a band gap lowering in the respective samples. Additional theoretical investigations, mostly based on Monte-Carlo methods, tried to understand the atomistic origin of this disorder induced band gap lowering. Here, we present theoretical results from first-principles calculations based on density functional theory for the disorder induced band gap lowering in kesterite Cu2ZnSnSe4 and Ag2ZnSnSe4, where the Cu–Zn and Ag–Zn disorder is modelled via a supercell approach and special quasirandom structures. Results of subsequent analyses of structural, electronic, and optical properties are discussed with respect to available experimental results, and will provide additional insight and knowledge towards the atomistic origin of the observed disorder induced band gap lowering in kesterite type materials.
HTR+: a novel algorithm for identifying type and polycrystal of gas hydrates
Authors: Shi Qiao , Lin Ziyan , Qu Yongxiao , Wu Jianyang , Zhang Zhisen 
Published: May 2024

Abstract
In this work, the hierarchical topology ring (HTR+) algorithm, an extension of the HTR algorithm, was developed for identifying gas hydrate types, cage structures, and grain boundaries (GBs) within polycrystalline structures. Utilizing molecular dynamics trajectories of polycrystalline hydrates, the accuracy of the HTR+ algorithm is validated in identifying sI, sII and sH hydrate types, hydrate grains, and GBs in multi-hydrate polycrystals, as well as clathrate cages at GBs. Additionally, during the hydrate nucleation and growth processes, clathrate cages, hydrate type, hydrate grains and ice structures are accurately recognized. Significantly, this algorithm demonstrates high efficiency, particularly for large hydrate systems. HTR+ algorithm emerges a powerful tool for identifying micro/mesoscopic structures of gas hydrates, enabling an in-depth understanding of the formation mechanisms and properties of gas hydrates.
Crystal structure, properties and pressure-induced insulator-metal transition in layered kagome chalcogenides
Authors: Du Hong , Zheng Yu , Pei Cuiying , Yim Chi-Ming , Qi Yanpeng , Zhong Ruidan 
Published: May 2024

Abstract
Layered materials with kagome lattice have attracted a lot of attention due to the presence of nontrivial topological bands and correlated electronic states with tunability. In this work, we investigate a unique van der Waals (vdW) material system, A
2
M
3
X
4 (A = K, Rb, Cs; M = Ni, Pd; X = S, Se), where transition metal kagome lattices, chalcogen honeycomb lattices and alkali metal triangular lattices coexist simultaneously. A notable feature of this material is that each Ni/Pd atom is positioned in the center of four chalcogen atoms, forming a local square-planar environment. This crystal field environment results in a low spin state S= 0 of Ni2+/Pd2+. A systematic study of the crystal growth, crystal structure, magnetic and transport properties of two representative compounds, Rb2Ni3S4 and Cs2Ni3Se4, has been carried out on powder and single crystal samples. Both compounds exhibit nonmagnetic p-type semiconducting behavior, closely related to the particular chemical environment of Ni2+ ions and the alkali metal intercalated vdW structure. Additionally, Cs2Ni3Se4 undergoes an insulator-metal transition (IMT) in transport measurements under pressure up to 87.1 GPa without any structural phase transition, while Rb2Ni3S4 shows the tendency to be metalized.
Remaining useful life prediction method of rolling bearings based on improved 3σ and DBO-HKELM
Authors: Gao Shuzhi , Li Zeqin , Zhang Yimin , Zhang Sixuan , Zhou Jin 
Published: May 2024

Abstract
An improved 3σ method and dung beetle algorithm optimization hybrid kernel extreme learning machine-based (DBO-HKELM) approach for predicting the remaining useful life (RUL) of rolling bearings was suggested in order to increase prediction accuracy. Firstly, multi-dimensional degradation feature data is extracted from bearing vibration data. Considering the influence of noise signal on the prediction accuracy, an improved kernel principal component analysis method is proposed to reduce the noise of degraded features. Then, an improved 3σ method is proposed to determine the starting point of bearing degradation by combining bearing vibration signal data. Lastly, a DBO-HKELM life prediction model was put forth. The parameters of hybrid kernel extreme learning machine were optimized by dung beetle algorithm, and appropriate kernel parameters and regularization coefficient were selected. The feature set of degradation indicators is input into the trained model to output the bearing RUL prediction results starting from the determined degradation starting point. Multiple data sets were used to verify that the new RUL prediction method significantly improves the prediction accuracy.
Design of SEE-Tolerant analog switch chip with a novel diode structure
*
Authors: Huang Wei , Liu HongXia , Xu Qing 
Published: May 2024

Abstract
This paper proposes a novel circuit-level design in order to enhance the radiation tolerance of an analog switch integrated circuit. After analyzing the mechanisms of single-particle sensitivity in a high-voltage analog switch chip fabricated using a commercial 1 μm complementary metal–oxide–semiconductor process, a diode unit was employed to reduce the V
GS (voltage between the gate and the base) of the parasitic triode within the metal–oxide–semiconductor field-effect transistor of the switch. This reduction lowered the probability of activating the parasitic triode in response to single-event effect (SEE). Subsequently, single-particle irradiation experiments proceeded with the high-voltage analog switch chip, both with and without the diode unit. In the unreinforced device, the current of the power supply reached 100 mA within 11 s of single-particle irradiation at 75.8 MeV•cm2 mg−1. In contrast, in the reinforced device, the current of the power supply remained relatively stable under irradiation at both 37.2 and 75.8 MeV•cm2 mg−1. These findings indicate that the reinforced analog switch chip exhibits an SEE tolerance exceeding 75.8 MeV•cm2 mg−1, highlighting its potential to enhance the radiation tolerance of analog switches.
Optical crosstalk of protective cover on MPPC array for TOF PET detector
Authors: Yoshida Eiji , Obata Fujino , Yamaya Taiga 
Published: May 2024

Abstract

Objective. Time-of-flight (TOF) is an important factor that directly affects the image quality of PET systems, and various attempts have been made to improve the coincidence resolving time (CRT) of PET detectors. For independent readout detectors, the timing is acquired for each silicon photomultiplier (SiPM), so they are less sensitive to diffused scintillation light, resulting in a better CRT. Further improvement can be expected if the light can be focused on a single SiPM. However, existing SiPM arrays have a thin protective cover on the SiPM and the gap between the SiPMs is filled with either air or the protective cover, so the light must diffuse through the cover. In this work, we investigated optical crosstalk in the protective cover to improve the CRT. Approach. We used 3.1 × 3.1 × 20 mm3 fast LGSO crystals and 3 mm square 8 × 8 multi pixel photon counter (MPPC) arrays. Pitch of the MPPCs was 3.2 mm and thickness of the protective cover on them was 150 μm. To reduce diffusion of scintillation light in the protective cover, the part of the inactive areas on the MPPC array were optically separated using reflective material. Specifically, 50, 100, 150, and 350 μm deep grid-shaped slits were made along the inactive area of the MPPCs and they were filled with BaSO4 powder as the reflective material. Main results. Coincidence counts were measured with a pair of TOF detectors, and the CRT was shorter with a deeper slit depth. The CRT before improvement was 235 ps, and using the cover having the 350 μm deep slits filled with reflective material lowered the CRT to 211 ps. Significance. Up to 10% of the scintillation light was diffused to other MPPCs by the protective cover, and the CRT was degraded by 10% due to optical crosstalk of the cover. The proposed method promises to improve the CRT of the TOF detector.
Deformable anthropomorphic pelvis phantom for dose accumulation verification
Authors: Wong Yun Ming , Koh Calvin Wei Yang , Lew Kah Seng , Chua Clifford Ghee Ann , Yeap Ping Lin , Zhang Ee Teng , Ong Ashley Li Kuan , Tuan Jeffrey Kit Loong , Ng Bing Feng , Lew Wen Siang , Lee James Cheow Lei , Tan Hong Qi 
Published: May 2024

Abstract

Objective. The validation of deformable image registration (DIR) for contour propagation is often done using contour-based metrics. Meanwhile, dose accumulation requires evaluation of voxel mapping accuracy, which might not be accurately represented by contour-based metrics. By fabricating a deformable anthropomorphic pelvis phantom, we aim to (1) quantify the voxel mapping accuracy for various deformation scenarios, in high- and low-contrast regions, and (2) identify any correlation between dice similarity coefficient (DSC), a commonly used contour-based metric, and the voxel mapping accuracy for each organ. Approach. Four organs, i.e. pelvic bone, prostate, bladder and rectum (PBR), were 3D printed using PLA and a Polyjet digital material, and assembled. The latter three were implanted with glass bead and CT markers within or on their surfaces. Four deformation scenarios were simulated by varying the bladder and rectum volumes. For each scenario, nine DIRs with different parameters were performed on RayStation v10B. The voxel mapping accuracy was quantified by finding the discrepancy between true and mapped marker positions, termed the target registration error (TRE). Pearson correlation test was done between the DSC and mean TRE for each organ. Main results. For the first time, we fabricated a deformable phantom purely from 3D printing, which successfully reproduced realistic anatomical deformations. Overall, the voxel mapping accuracy dropped with increasing deformation magnitude, but improved when more organs were used to guide the DIR or limit the registration region. DSC was found to be a good indicator of voxel mapping accuracy for prostate and rectum, but a comparatively poorer one for bladder. DSC > 0.85/0.90 was established as the threshold of mean TRE ⩽ 0.3 cm for rectum/prostate. For bladder, extra metrics in addition to DSC should be considered. Significance. This work presented a 3D printed phantom, which enabled quantification of voxel mapping accuracy and evaluation of correlation between DSC and voxel mapping accuracy.
Study of impurity C transport and plasma rotation in negative triangularity on the TCV tokamak
Authors: Bagnato F , Duval B P , Sauter O , Coda S , Karpushov A , Merle A , Labit B , Fevrier O , Pau A , Mykytchuk D , Porte L , Ball J 
Published: May 2024

Abstract
Carbon impurity transport is studied in the TCV tokamak using a charge exchange recombination diagnostic. TCVs flexible shaping capabilities were exploited to extend previous impurity transport studies to negative triangularity (δ < 0). A practical way of studying light impurity transport (like C, TCVs main impurity species due to graphite tiled walls) is to investigate the correlations between the impurity ion gradients that, in this study, highlighted significant differences between positive (PT) and negative δ (NT) plasma configurations. δ scans (

−
0.6
<
δ
<
+
0.6

) were performed in limited configurations, but displayed little correlation between C temperature, rotation and density gradients for positive δ. This stiff response for δ > 0 changes for negative δ, where the evolution of

∇

v

tor

was accompanied by variations of

∇

n

C

over a range of negative δ, showing that transport, in NT, is affected by velocity gradients. Similar δ scans were performed with additional NBH (Neutral Beam Heating), with power steps ranging from 0.25 MW to 1.25 MW, highlighting increased momentum confinement in negative δ. Finally, the evolution of intrinsic plasma toroidal rotation across linear to saturated ohmic confinement regime (LOC/SOC) transitions was explored at δ < 0, expanding previous studies performed in TCV for

δ
>

0 (Bagnato et al 2023 Nucl. Fusion
63 056006). Toroidal rotation reversal was not observed for δ < 0, despite clear LOC/SOC transitions, confirming that these two phenomena occur concomitantly only in a restricted number of cases and under specific conditions.
Trends in mass utilization of a magnetically shielded Hall thruster operating on xenon and krypton
Authors: Su Leanne L , Marks Thomas A , Jorns Benjamin A 
Published: May 2024

Abstract
The trends in mass utilization with increasing discharge voltage and current are investigated for a magnetically shielded Hall thruster operating on xenon and krypton. A 9 kW class shielded thruster is operated with discharge voltages from 300 to 600 V and discharge currents from 15 to 30 A on xenon and krypton. Experimental measurements of discharge current, thrust, anode efficiency, and ion velocity as a function of axial position are used to calibrate a multi-fluid 2D Hall thruster code at all operating conditions. The results of these calibrated simulations are employed to interrogate the plasma properties inside the thruster channel. A simplified 0D model for mass utilization evaluated on spatial averages of the simulated plasma parameters is employed to interpret the response of this efficiency mode with power for each propellant. It is found that with both higher voltage and current, mass utilization increases for both gases and their relative gap in this efficiency decreases. This can be attributed to the higher plasma densities and ionization rate coefficients at high voltage, and solely to higher plasma densities at high current. The driving factors for the increase in mass utilization are examined in the context of its nonlinear response to internal plasma properties. The behavior of mass utilization is also discussed in context of the gap in overall efficiency between the propellants. Finally, the implications of these results for improving the performance of high power Hall thrusters operating on krypton are examined.
Electron trapping efficiency of a magnetron sputtering cathode
Authors: Salahshoor Mostafa 
Published: May 2024

Abstract
A common feature of all types of magnetron sputtering (MS) assemblies is an effective confinement of electrons by an appropriate combination of electric and magnetic fields. Therefore, studying the motions of electrons in the fields of magnetron assemblies is of particular importance. Here, we systematically analyze the electrons motions in front of a typical DC MS cathode. We first calculate the profiles of the magnetron’s magnetic field for balanced and two types of unbalanced configurations. Then, we compute the profiles of the cathode’s electric field before the gas discharge and after the plasma formation. A semi-analytical model is utilized to compute the plasma potential. We then track the motions of electrons released from the target and electrons produced through impact ionization of the background gas in the prescribed fields. A Monte Carlo model is implemented to consider electron-gas collisions and a mixed boundary condition is employed to account for electron-wall interactions. The study analyzes the impact of field profiles on the cathode’s efficiency in trapping electron by examining electron escape from the magnetic trap and electron recapture at the target surface. It is shown that the presence of plasma in all configurations leads to a significant increase in the trapping efficiency and the ionization performance, as well as a decrease in the recapture probability. These effects are attributed to the high electric field developed in the cathode sheath. Moreover, we statistically analyze the trapping efficiency by illustrating the spatial distributions of electrons locations in both axial and radial dimensions. It is demonstrated that during their azimuthal drift motion, the electrons released from the middle region at the target surface have the smallest range of axial and radial locations, in all configurations in the absence of plasma. Finally, the impact of field profiles on the average energies of electrons is discussed.
Incorporation of zinc oxide and cobalt doped zinc oxide nano-rods in commercial sunscreen sample to optimize its UV-ray absorption
Authors: Ansari Komal , Riaz Rehana , Gull Fatima , Atiq Haleema 
Published: May 2024

Abstract
In the last two decades, the ozone layer in the atmosphere has been depleted, and the sun rays are now more harmful to human skin because they no longer filters it completely. Long-term exposure to harmful ultraviolet rays (UV-rays), which have wavelengths between 220 nm and 380 nm, causes catastrophic damage to skin cells. Sunscreens are therefore absolutely necessary to protect the skin. The co-precipitation method was used to synthesize both pure and cobalt-doped zinc oxide nano structures. In sunscreens, these nanostructures serve as a UV filter. The obtained nano structures have been characterized by x-ray diffraction (XRD), scanning electron microscopy (SEM), and diffuse reflectance spectroscopy (DRS). The ability of a sunscreen sample containing nano structures to yield results for a period of various hours at different temperatures (20 °C, 30 °C, and 50 °C) has been tested. According to XRD results, prepared samples exhibits hexagonal wurtzite crystalline structures and are of 22 nm in size for pure zinc oxide and 20 nm in size for cobalt- doped zinc oxide. SEM was used to find morphologies, i.e., nano rods (NRs) at 200 nm and 2 μm. DRS provided evidence of sunscreen’s endurance, with a 97% absorption of UV-rays at 50 °C for up to 6 h when incorporated with NRs. In order to boost UV-ray absorption in sunscreen, nanotechnology has been successfully applied.
Emergent cosmology in 4D Einstein Gauss Bonnet theory of gravity
Authors: Gohain Mrinnoy M , Bhuyan Kalyan 
Published: May 2024

Abstract
In this paper, in an FLRW background and a perfect fluid equation of state, we explore the possibility of the realization of an emergent scenario in a 4D regularized extension of Einstein-Gauss-Bonnet gravity, with the field equations particularly expressed in terms of scalar-tensor degrees of freedom. By assuming non-zero spatial curvature (k = ± 1), the stability of the Einstein static universe (ESU) and its subsequent exit into the standard inflationary scenario is tested through different approaches. In terms of dynamical systems, a spatially closed universe rather than an open universe shows appealing behaviour to exhibit a graceful transition from the ESU to standard cosmological history. We found that under linear homogeneous perturbations, for some constraints imposed on the model parameters, the ESU is stable under those perturbations. Moreover, it is noted that for a successful graceful transition, the equation of state ω must satisfy the conditions −1 < ω < 0 and ω < − 1 for closed and open universes, respectively. Furthermore, the ESU is seen to be neutrally stable under matter perturbation in the Newtonian gauge.
A discretization-free deep neural network-based approach for advection-dispersion-reaction mechanisms
Authors: Uslu Tuna Hande , Sari Murat , Cosgun Tahir 
Published: May 2024

Abstract
This study aims to provide insights into new areas of artificial intelligence approaches by examining how these techniques can be applied to predict behaviours for difficult physical processes represented by partial differential equations, particularly equations involving nonlinear dispersive behaviours. The current advection-dispersion-reaction equation is one of the key formulas used to depict natural processes with distinct characteristics. It is composed of a first-order advection component, a third-order dispersion term, and a nonlinear response term. Using the deep neural network approach and accounting for physics-informed neural network awareness, the problem has been elaborately discussed. Initial and boundary conditions are added as constraints when the neural networks are trained by minimizing the loss function. In comparison to the existing results, the approach has produced qualitatively correct kink and anti-kink solutions, with losses often remaining around 0.01%. It has also outperformed several traditional discretization-based methods.
Invariant analysis of the two-cell tumor growth model in the brain
Authors: Hussain Akhtar , Usman Muhammad , Zaman F D 
Published: May 2024

Abstract
In this study, we explore the invariance properties of a tumor growth model involving two distinct cell populations. These populations are characterized by different diffusion coefficients but share a common killing rate. This particular model serves as a representation of tumor growth within the brain. By employing the Lie group method, we unveil a two-dimensional symmetry algebra for cases where both diffusion coefficients are allowed to vary arbitrarily. Interestingly, this method reveals a nine-dimensional symmetry algebra when the diffusion coefficients are held constant. In both scenarios involving varying and constant diffusion coefficients, we conduct similarity reductions to deduce group invariant solutions, thus elucidating the model’s behavior. Notably, our findings demonstrate that the tumor’s growth remains exponential irrespective of the presence or absence of a killing rate. This remarkable phenomenon holds for various configurations of diffusion coefficients. To validate our observations, we employ Mathematica simulations, which corroborate the model’s exponential growth behavior and emphasize the role of killing rates, diffusion coefficients, and growth rate parameters in driving this exponential trend. Also, the conserved flows and conserved quantities of the model are demonstrated.