bluuebunny/crossref_metadata_2025_split huggingface dataset:
Modeling of tungsten impurity transport and distribution in EAST based on multi-fluid and kinetic Monte Carlo simulations
Authors: Wen Ziyang , Chen YiPing , Zhang Ling 
Published: May 2024

In recent years, the materials of plasma facing components, such as divertor target plates, domes, and outer walls of tokamaks, such as ASDEX Upgrade, WEST, JET, EAST, and ITER, have been changed from carbon to tungsten because of its lower erosion and tritium retention rates. Impurities are produced by interactions between the plasma and the first wall. This study provides an investigation to simulate the transport and distribution of tungsten impurities in the edge plasma on EAST. The 2D multi-fluid edge plasma transport code SOLPS-ITER and 2D kinetic Monte Carlo impurity transport code DIVIMP were used in the simulations. The multi-fluid model in SOLPS-ITER and the kinetic Monte Carlo model in DIVIMP were employed to treat tungsten impurity ions. The 2D density contour distributions in the computational region and the 1D density radial profiles at the inner and outer midplanes of tungsten impurity particles with ionization states (W0–W+74) and the total tungsten particles with all charge states were obtained. With the heating power 1.5 MW and the line-averaged plasma density 2 × 1019 m−3, the results from SOLPS-ITER and DIVIMP show that the maximum density of tungsten ion with single ionization state is about 1014 m−3 and the total density of tungsten impurities with all charge states is about 1015 m−3 at the core boundary. To the best of our knowledge, the simulation results from SOLPS-ITER and DIVIMP are compared for the first time to benchmark SOLPS-ITER with the multi-fluid mode and DIVIMP with the kinetic model for tungsten impurity transport. The density distributions of tungsten impurities with different ionization states from SOLPS-ITER and DIVIMP are highly similar, and good agreement can be found under similar conditions involved in the calculation. From the comparison benchmark between SOLPS-ITER and DIVIMP for tungsten impurity transport, it can be concluded that the impurity transport approximation used by DIVIMP is good.
Spot size measurement of a deuterium–tritium dense plasma focus using neutron radiography
Authors: Tafoya L. , Geppert-Kleinrath V. , Allison J. , Baker S. , Bundgaard J. , Freeman M. , Hayes-Sterbenz A. , Jungman G. , Li H. , Li S. , Lowe D. , Tybo J. , Wilde C. 
Published: May 2024

Neutron radiography is a technique uniquely suited to applications in nuclear diagnostics, non-destructive testing, and subcritical experiments. The spatial resolution of neutron radiographs is degraded by optical blur in the imaging system and the neutron source size, where the ideal source is point-like to optimize the point-spread function. A potential neutron source for radiography is the dense plasma focus (DPF), a coaxial Z-pinch that produces thermonuclear and beam-target neutrons. To assess if the source size is suitable for radiography, a neutron imaging system was used to measure the source size of the 4 MA Sodium DPF at the Nevada National Security Site operating with deuterium–tritium gas-fill. The source size was measured using the edge-spread function of tungsten objects, each having a rolled (convex) edge. The spot size was found to be 7–12 mm full-width at half-max (FWHM) assuming a Gaussian source, though comparison is presented for Lorentzian and Bennett distributions. The average FWHM was found to be 8.6 ± 1.2 mm vertically and 10.8 ± 1.2 mm horizontally with respect to the image plane, averaging over varied edges and alignments. The results were sensitive to source alignment and edge metrology, which introduced notable uncertainties. These results are consistent with separate experimental measurements as well as magnetohydrodynamics simulations of this DPF, which suggest that neutron production can originate from pinches ∼5–7 mm off-axis. These results suggest that the DPF should be used for radiography at low magnification (M &lt; 1) where spot size does not dominate spatial blur.
Optical response and temperature shielding coatings using tri-layer structure composed of titania/silica/titania
Authors: Yepuri Venkatesh , Balamurugan K. 
Published: May 2024

The fabrication of metamaterials with inspiration from nature paved the door for the creation of revolutionary passive and active devices. Butterfly wings are one of them, and their multilayered structure motivated nanotechnologists, physicists, and other optoelectronic and photonic engineers to develop photonic crystals, dielectric reflectors, and Bragg reflectors for use in visible light communication, solar cells, and other photonic and optoelectronic applications. We report the sol–gel spin coating of a dielectric reflector on the glass substrate, an optical passive component consisting of titania and silica thin films for infrared radiation reflection. Individual thin films of titania and silica on glass substrates were studied using an x-ray diffractometer, which indicated anatase of titania and the amorphous nature of silica at a Bragg angle of 25° with a sharp and wide peak, respectively. The multilayer structure of titania/silica/titania was further investigated using Fourier transform infrared spectroscopy, which revealed the presence of Ti–O–Ti and Si–O–Si vibrational bonds at wavenumbers 546 and 973 cm−1, respectively, as well as the presence of Ti–O–Si vibrational bond at 1100 cm−1. The thickness of the multilayer titania/silica/titania was measured using a cross-sectional field emission scanning electron microscope (FESEM) and found to be 160/240/160 nm, respectively. Finally, reflection investigation on the multilayer structure using ultraviolet–visible–near-infrared spectroscopy validated the reflection of the infrared spectrum area by around 70% and showed to be beneficial for temperature shielding applications on glass furnishings.
Two-dimensional electron gases in AlYN/GaN heterostructures grown by metal–organic chemical vapor deposition
Authors: Streicher Isabel , Straňák Patrik , Kirste Lutz , Prescher Mario , Müller Stefan , Leone Stefano 
Published: May 2024

Wurtzite AlN alloyed with group 3 elements Sc and Y boosts the performance of GaN-based high-electron-mobility transistors (HEMTs) significantly as they increase the spontaneous polarization of the barrier layer and, thus, enhance the charge carrier density ns in the two-dimensional electron gas (2DEG) formed at the interface with the GaN channel. The emerging nitride Al1−xYxN additionally features an a lattice parameter matching to that of GaN at x = 0.07–0.11, allowing for the growth of strain-free barriers. Here, we demonstrate the growth of Al1−xYxN/GaN heterostructures for HEMTs by metal–organic chemical vapor deposition for the first time. The effect of the Y concentrations on the 2DEG is investigated in a Y concentration range from 3% to 15%. At 8% Y, a record mobility of 3200 cm2/(Vs) was measured at a low temperature (7 K). Room and low-temperature ns was at 1–2 × 1013 cm−2. Al0.92Y0.08N barriers were coherently strained to the GaN channel for barrier thicknesses from 5 to 15 nm. Finally, the deposition of Al1−xYxN/GaN heterostructures deposited on 4″ 4H–SiC wafers had a room-temperature mobility close to 1400 cm2/(Vs). AlYN/GaN heterostructures may offer advantages over AlScN/GaN heterostructures not only for the lower price and higher abundance of the raw material but also in terms of electrical characteristics and may be more suitable for power amplifying applications due to increased electron mobility.
Nanofluid cooling of a hot rotating circular cylinder employing cross-flow channel cooling on the upper part and multi-jet impingement cooling on the lower part
Authors: Selimefendigil Fatih , Larguech Samia , Ghachem Kaouther , Albalawi Hind , Alshammari Badr M. , Labidi Taher , Kolsi Lioua 
Published: May 2024

This study explores the convective cooling features of a hot rotating cylinder by using the combined utilization of cross-flow on the upper part and multi-jet impingement on the bottom part. The analysis is performed for a range of jet Reynolds number (Re) values (between 100 and 500), cross-flow Re values (between 100 and 1000), rotational Re values (between −1000 and 1000), cylinder size (between 0.25wj and 3wj in radius), and center placement in the y direction (between −1.5wj and 1.5wj). When the cylinder is not rotating, the average Nu increment becomes 102% at the highest jet Re, while it becomes 140.82% at the highest cross-flow Re. When rations become active, the impacts of cross-flow and jet impingement cooling become slight. As compared to a motionless cylinder, at the highest speed of the rotating cylinder, the average Nu rises by about 357% to 391%. For clockwise rotation of the cylinder, a lager cylinder results an increase in the average Nu by about 86.3%. At the lowest and highest cross-flow impinging jet Re value combinations, cooling performance improvement becomes a factor of 8.1 and 2, respectively. When the size of the cylinder changes, entropy generation becomes significant, while the vertical location of the cylinder has a slight impact on entropy generation.
Research on development and quantitative control preparation technology of array-type microfine bubbles generator
Authors: Huang Zhijie , Zhang Yufeng , Sun Lixia , Wang Zheng , Wang Qin , Liu Yang 
Published: May 2024

In traditional wastewater treatment, ozone injection efficiency is low. There is a need for the quantitative preparation of ozone-based microfine bubbles to balance bubble stability and ozone reactivity. To address this, we developed coaxial and T-type ozone-based microfine bubble generators and conducted experiments to compare their bubble production effects. The more effective generator was then compared with the traditional aeration method. The results indicate the following: 1. The coaxial type is more effective in producing ozone-based microfine bubbles. 2. The bubbles produced by the coaxial type have an average diameter of 0.2–0.4 mm and a residence time of ∼2 min, meeting microfine bubble standards. Experimental data analysis shows compliance with the force process and bubble growth mechanism under coaxial flow, meeting the requirements for quantitative and controllable ozone-based microfine bubble production. 3. Ozone bubbles from the coaxial method surpass those from traditional aeration in volume and concentration. More than 99.73% are microfine bubbles, with an ozone concentration of ∼84.5%. 4. The coaxial method more effectively reduces COD values in water, contributing to efficient wastewater treatment. This research presents new avenues for efficient sewage treatment.
An investigation of self-interstitial diffusion in α-zirconium by an on-the-fly machine learning force field
Authors: Shi Tan , Liu Wenlong , Zhang Chen , Lyu Sixin , Sun Zhipeng , Peng Qing , Li Yuanming , Meng Fanqiang , Tang Chuanbao , Lu Chenyang 
Published: May 2024

The on-the-fly machine learning force field approach, based on the Gaussian approximation potential and Bayesian error estimation, was used to study the diffusion of self-interstitial atoms in α-zirconium. Ab initio molecular dynamics simulations of lattice vibration and interstitial diffusion at different temperatures were employed to develop the force field. The radial and angular descriptors of the potential were further optimized to achieve better agreement with first-principles results. Subsequent long-term diffusion simulations were performed to assess the diffusion behavior based on the obtained force field. Tracer diffusion coefficients and diffusion anisotropy were studied at temperatures of 600–1200 K, and the Bayesian errors were estimated throughout the diffusion simulations. The mean and maximum estimated Bayesian errors of atomic force were approximately twice as large as those observed during the learning period. The basal diffusion was greatly favored compared to the interstitial diffusion along the c-axis, consistent with previous simulations based on first-principles results and classical potentials. The accuracy and applicability of the current on-the-fly machine learning approach were critically evaluated.
Sperm functionality is differentially regulated by porcine oviductal extracellular vesicles from the distinct phases of the estrous cycle
Authors: Toledo-Guardiola S. M. , Martínez-Díaz P. , Martínez-Núñez R. , Navarro-Serna S. , Soriano-Úbeda C. , Romero-Aguirregomezcorta J. , Matás C. 
Published: May 2024

Context Extracellular vesicles (EVs) derived from the oviductal fluid (oEVs) play a critical role in various reproductive processes, including sperm capacitation, fertilisation, and early embryo development. Aims To characterise porcine oEVs (poEVs) from different stages of the estrous cycle (late follicular, LF; early luteal, EL; mid luteal, ML; late luteal, LL) and investigate their impact on sperm functionality. Methods poEVs were isolated, characterised, and labelled to assess their binding to boar spermatozoa. The effects of poEVs on sperm motility, viability, acrosomal status, protein kinase A phosphorylation (pPKAs), tyrosine phosphorylation (Tyr-P), and in in vitro fertility were analysed. Key results poEVs were observed as round or cup-shaped membrane-surrounded vesicles. Statistical analysis showed that poEVs did not significantly differ in size, quantity, or protein concentration among phases of the estrous cycle. However, LF poEVs demonstrated a higher affinity for binding to sperm. Treatment with EL, ML, and LL poEVs resulted in a decrease in sperm progressive motility and total motility. Moreover, pPKA levels were reduced in presence of LF, EL, and ML poEVs, while Tyr-P levels did not differ between groups. LF poEVs also reduced sperm penetration rate and the number of spermatozoa per penetrated oocyte (P < 0.05). Conclusions poEVs from different stages of the estrous cycle play a modulatory role in sperm functionality by interacting with spermatozoa, affecting motility and capacitation, and participating in sperm–oocyte interaction. Implications The differential effects of LF and LL poEVs suggest the potential use of poEVs as additives in IVF systems to regulate sperm–oocyte interaction.
The electronic structures and optical properties induced by spin-orbit-coupling in LiPbPO4 compound
Authors: Leng Xudong , Hu Mei , Jing Qun , Duan Haiming , Chen Henglei , Chen Zhaohui 
Published: May 2024

Abstract
Phosphate materials are excellent candidates for nonlinear optical materials, thus necessitating a comprehensive and in-depth study of them. Here, inspired by the interesting phenomenon induced by the spin-orbit coupling (SOC) effect, we extend it to LiPbPO4 compounds using a first-principles approach to probe the influence of SOC on the electronic structure and optical properties of post-transition metal compounds. The results show that only the bottom of the conduction band shows an energy level splitting with the inclusion of SOC, which is analyzed to come from the SOC in the Pb 6p state since the SOC in the O 2p state is very weak. The splitting of the conduction band triggers the decrease of the band gap and the change of the optical properties. The performance analysis shows that both the refractive index and the second harmonic generation (SHG) coefficient are enhanced with the inclusion of SOC, however, the change in the birefringence is insignificant, and it is further found that the enhanced SHG coefficient values are closer to the experimental values. In conclusion, our study reveals the impact of SOC effect on the electronic structure and optical properties of LiPbPO4 compounds, contributing to a deeper understanding of the nonlinear optical in post-transition metal compounds.
Coaxial tips for a scanning microwave microscope and its calibration with dielectric references
Authors: Eckmann Bruno , Herzog Benedikt , Lin Hung-Ju , de Préville Sophie , Hoffmann Johannes , Zeier Markus 
Published: May 2024

Abstract
Scanning microwave microscopy (SMM) is a combination of an atomic force microscope with a vector network analyzer (VNA) to measure locally resolved impedances. The technique finds application in the realms of semiconductor industries, material sciences, or biology. To determine quantitative material properties from the measured impedances, the system must be calibrated. Transferring the calibration from the calibration substrate onto the material under test is strongly limited when using unshielded probes, as the electromagnetic coupling to the surroundings can reach several centimeters. This work reports the fabrication of coaxially shielded probes for a scanning microwave microscope and their integration into such an instrument. We discuss a calibration method with dielectric references, using a simulation-assisted 1-port VNA calibration algorithm. Uncertainty considerations of the measurement process are included and propagation throughout the algorithm is performed. The calibration is verified with an additional dielectric reference. As an application example, the results for a static-random-access memory sample are presented. We identified system-related drift and trace noise as the dominant contributors to the uncertainties of the calibrated results. The here presented shielded tips can broaden the application scope of SMM, as they are door-openers for measurements in liquids.
Drill tools sticking prediction based on adaptive long short-term memory
Authors: Wu Honglin , Wang Zhongbin , Si Lei , Zou Xiaoyu 
Published: May 2024

Abstract
As one of the most severe disasters in deep coal mining, rockburst can be prevented through drill-hole pressure relief. However, the coal mine is characterized by high crustal stress and changeable mechanical properties of surrounding rock, which will cause drill rod deflection phenomenon, then lead to rod-deflection sticking accidents. This paper proposes a prediction method based on adaptive long short-term memory (ALSTM) for rod-deflection sticking accidents to improve drilling efficiency and reduce sticking accidents. Firstly, the sticking data is collected through the intelligent drilling condition simulation experimental platform, and then the sticking features are extracted based on the sticking data. Secondly, the sticking factor is constructed, and the sticking critical line is set. Thirdly, the good-point set and the proposed random perturbation algorithm are employed to improve the spotted hyena optimizer (SHO) to obtain the improved SHO (ISHO). Finally, we use the ISHO to optimize the hyperparameters of the long short-term memory and then establish the sticking prediction model based on ALSTM. The experimental results show that the proposed prediction model meets the demands for sticking prediction very well.
Velocity-space distribution function of fast ions in a sawtoothing plasma
Authors: Barberis T , Porcelli F 
Published: May 2024

Abstract
This study explores the influence of sawtooth oscillations on the velocity space distribution of fast ions in tokamak plasma discharges. The relevant Fokker–Planck equation for fast ions is solved analytically. Two distinct effects arising from the temperature drop associated with a sawtooth crash and their impact on the distribution function of fast ions are considered. The first effect involves the modulation of the fusion alpha particle source on the timescale of the sawtooth period, linked to the drop in fusion yield resulting from the sawtooth temperature relaxations. The second effect is tied to the increase of the slowing-down time during the sawtooth ramp, causing particles born later in the sawtooth cycle to experience reduced slowing down compared to those born right after the crash, creating an accumulation-like mechanism at higher energies. In regimes where the sawtooth period is shorter than the fast ion slowing-down time, the combined influence of these effects gives rise to fast ion distribution functions that transiently exhibit positive slopes in velocity space.
In-situ synchrotron x-ray photoelectron spectroscopy study of medium-temperature baking of niobium for SRF application
Authors: Prudnikava A , Tamashevich Y , Makarova A , Smirnov D , Knobloch J 
Published: May 2024

Abstract
In order to determine optimal parameters of vacuum thermal processing of superconducting radiofrequency niobium cavities exhaustive information on the initial chemical state of niobium and its modification upon a vacuum heat treatment is required. In the present work the chemical composition of the niobium surface upon ultra-high vacuum baking at 200 ∘C–400 ∘C similar to ‘medium-temperature baking’ and ‘furnace baking’ of cavities is explored in-situ by synchrotron x-ray photoelectron spectroscopy (XPS). Our findings imply that below the critical thickness of the

Nb
2

O
5

layer (

≈

1
nm

) niobium starts to interact actively with surface impurities, such as carbon and phosphorus. By studying the kinetics of the native oxide reduction, the activation energy and the rate-constant relation have been determined and used for the calculation of the oxygen-concentration depth profiles. It has been established that the controlled diffusion of oxygen is realized at temperatures 200 ∘C–300 ∘C, and the native-oxide layer represents an oxygen source, while at 400 ∘C the pentoxide is completely reduced and the doping level is determined by an ambient oxygen partial pressure. Fluorine (F to Nb atomic ratio is 0.2) after the buffered chemical polishing was found to be incorporated into the surface layer probed by XPS (

≈

4.6

nm

), and its concentration increased during the low-temperature baking (F/Nb = 0.35 at 230 ∘C) and depleted at higher temperatures (F/Nb = 0.11 at 400 ∘C). Thus, the influence of fluorine on the performance of mid-T baked, nitrogen-doped and particularly mild-baked (120 ∘C/48 h) cavities must be considered. The possible role of fluorine in the educed

Nb

+
5

→

Nb

+
4

reaction under the impact of an x-ray beam at room temperature and during the thermal treatment is also discussed. The range of temperature and duration parameters of the thermal treatment at which the niobium surface would not be contaminated with impurities is determined.
Effects of nanomagnesia and polypropylene-graft-maleic anhydride on the dielectric breakdown properties of polypropylene/ethylene propylene diene monomer blend
Authors: Johari Nur Atikah , Lau Kwan Yiew , Abdul Malek Zulkurnain , Mohd Esa Mona Riza , Ching Kuan Yong , Talib Mohd Aizam 
Published: May 2024

Abstract
Thermoplastic polypropylene (PP) has garnered a significant attention in power cable insulation research because of its exceptional thermal tolerance and dielectric properties. Due to its poor impact strength at room temperature, PP has been blended with various elastomers, including ethylene-propylene-diene monomer (EPDM), to improve the mechanical stiffness of the final material. This, however, comes with compromised dielectric properties of the material. Recently, the addition of nanofillers to polymers has demonstrated promising properties that can be tailored for various dielectric applications, provided that nanofiller and polymer interactions are appropriately formulated. Nevertheless, the effect of nanostructuration in PP/elastomer blends, especially from the perspective of dielectrics, have yet to be systematically explored. In the current work, magnesia (MgO) nanofiller is added to a model PP/EPDM blend system to determine the effect of MgO on the breakdown properties of PP/EPDM. The results show that adding 0.5 wt% of MgO to PP/EPDM reduces the AC and DC breakdown strengths by 7% and 16%, respectively. As the amount of MgO increases to 3 wt%, the AC and DC breakdown strength reduces further by 25% and 29%, respectively. Significantly, appropriate modification of the nanocomposites with polypropylene-graft-maleic anhydride (PP-g-MAH) can result in 5% higher breakdown strength of the nanocomposites with respect to comparable nanocomposites without modification. The mechanisms surrounding these breakdown effects are discussed with the aid of materials structure interpretations. Overall, the results demonstrate that appropriate modification of nanocomposites with PP-g-MAH is crucial in tailoring breakdown properties of PP blend nanocomposites.