bluuebunny/crossref_metadata_2025 huggingface dataset:
Impact of Mg-doping on the performance and degradation of AlGaN-based UV-C LEDs
Authors: Piva F. , Grigoletto M. , Brescancin R. , De Santi C. , Buffolo M. , Ruschel J. , Glaab J. , Hauer Vidal D. , Guttmann M. , Rass J. , Einfeldt S. , Susilo N. , Wernicke T. , Kneissl M. , Meneghesso G. , Zanoni E. , Meneghini M.
Published: April 2023

We investigate the impact of Mg-doping on the performance and degradation kinetics of AlGaN-based UV-C light-emitting diodes (LEDs). By comparing LEDs from three wafers with different nominal doping levels [Mg/(Al+Ga) ratio: 0.15%, 0.5%, and 1% in the gas phase during epitaxy] in the AlGaN:Mg electron-blocking layer (EBL), we demonstrate the following results: (i) A higher Mg-doping in the EBL results in a higher optical power at low current levels, which is ascribed to an increased hole injection efficiency. (ii) The reduction of the optical power follows a non-exponential trend, which can be reproduced by using the Hill's formula and is ascribed to the generation/activation of defects within the quantum wells. (iii) A higher Mg-doping in the EBL mitigates the degradation rate. An interpretation of the experimental data is proposed, assuming that hydrogen, which is present in and moving from the EBL, can reduce the rate of de-hydrogenation of point defects in the active region, which is responsible for degradation.
Design of a plasma-based intelligent reflecting surface
Authors: Magarotto M. , Schenato L. , De Carlo P. , Santagiustina M. , Galtarossa A. , Capobianco A.-D.
Published: April 2023

Plasma-based intelligent reflecting surfaces (IRSs) have been recently proposed to reconfigure the radiation environment between transmitting and receiving antennas. Plasma-based IRSs rely on elements whose electromagnetic response is electronically controlled by varying the plasma density. Here, for the first time, the numerical design of an IRS is based on plasma discharges at the state-of-the-art. First, a cylindrical discharge has been realized and tested to identify realistic plasma parameters and geometries. Second, the design of a plasma-based IRS is proposed, accounting for practical constraints, such as the presence of the glass vessels needed to confine the plasma, the metal electrodes used to sustain the discharge, and the non-uniformity of the plasma parameters (e.g., density). Remarkably, at a central frequency of 10 GHz, a fractional bandwidth larger than 10% is feasible.
Quadratic symplectic Lie superalgebras with a filiform module as an odd part
Authors: Barreiro Elisabete , Benayadi Saïd , Navarro Rosa M. , Sánchez José M.
Published: April 2023

The present work studies deeply quadratic symplectic Lie superalgebras, obtaining, in particular, that they are all nilpotent. Consequently, we provide classifications in low dimensions and identify the double extensions that maintain symplectic structures. By means of both elementary odd double extensions and generalized double extensions of quadratic symplectic Lie superalgebras, we obtain an inductive description of quadratic symplectic Lie superalgebras of filiform type.
Topological Data analysis of Ion Migration Mechanism
Authors: Sato Ryuhei , Akagi Kazuto , Takagi Shigeyuki , Sau Kartik , Kisu Kazuaki , Li Hao , Orimo Shin-ichi
Published: April 2023

Topological data analysis based on persistent homology has been applied to the molecular dynamics simulation for the fast ion-conducting phase (α-phase) of AgI to show its effectiveness on the ion migration mechanism analysis. Time-averaged persistence diagrams of α-AgI, which quantitatively record the shape and size of the ring structures in the given atomic configurations, clearly showed the emergence of the four-membered rings formed by two Ag and two I ions at high temperatures. They were identified as common structures during the Ag ion migration. The averaged potential energy change due to the deformation of the four-membered ring during Ag migration agrees well with the activation energy calculated from the conductivity Arrhenius plot. The concerted motion of two Ag ions via the four-membered ring was also successfully extracted from molecular dynamics simulations by our approach, providing new insight into the specific mechanism of the concerted motion.
Modeling of discharge characteristics and plasma chemistry in atmospheric CO2 pulsed plasmas employing deep neural network
Authors: Wang Xu-Cheng , Zhang Yuan-Tao
Published: April 2023

In recent years, non-thermal plasma technology has emerged as one of the most promising candidates for decomposing CO 2. The fluid model, a powerful tool to investigate the plasma dynamics, is computationally costly in simulating complex CO 2 plasma with tens of particles and hundreds of reactions, especially driven by short pulsed voltages. In this paper, a deep neural network (DNN) is proposed to describe the discharge characteristics and plasma chemistry of CO 2 pulsed discharge at atmospheric pressure. The DNN is trained using the simulation data obtained from the fluid model and then continuously optimized by minimizing the loss function. The effectiveness and feasibility of the DNN are verified by comparing with the experimental measurement and the numerical simulation results. Compared to the time-consuming fluid simulations with tens of hours, the well-trained DNN typically requires only a few seconds to obtain the essential characteristics of CO 2 pulsed discharges with high accuracy, significantly improving the computational efficiency. The DNN prediction results show that increasing the pulse rise rate at a given voltage amplitude can effectively raise the discharge current and breakdown voltage, and the electric field in the sheath region also increases with the pulse rise rate. In addition, the density of the surface charge accumulated on the dielectric layer increases with the plateau duration, and then a strong induced electric field by the surface charges is established, which obviously improves the discharge current during the pulse fall phase. The predicted data also show that increasing the pulse rise rate and the plateau duration could effectively improve the density of product species, such as CO and O 2, leading to an increase in CO 2 conversion. This study demonstrates that the DNN method is a reliable tool for obtaining the essential discharge characteristics of atmospheric CO 2 pulsed plasma and provides a promising avenue for future applications of DNN-based methods in non-thermal plasmas.
An investigation of the effects of wall materials on flame dynamics inside a H2-air micro-combustor
Authors: Kundu Debjit , Bhattacharya Arijit , Sarkar Sourav , Sarkar Sandip , Mukhopadhyay Achintya
Published: April 2023

Micro-combustors, which are emerging as portable power sources, have serious flame stabilization issues due to enhanced heat losses. Hydrogen, an eco-friendly alternative to conventional fossil fuels, can be a potential fuel for micro-combustors because of its high calorific value, leading to high energy density. In the present work, numerical simulations of premixed lean (equivalence ratio = 0.5) hydrogen-air flames in a 2 mm wide channel with three different wall materials (glass, steel, and aluminum) were performed. The effects of the wall material on the dynamics of the flames were extensively studied. The walls of the combustor play an important role by conducting heat upstream and facilitating ignition and stabilization of the flame. For different values of wall thermal diffusivity, periodically oscillating flames of varying frequencies ( ∼ 400 − 1200   Hz) and intermittent bursting flames were observed. Time series analysis and modal decomposition of temperature fields were utilized to quantify the flame dynamics and to identify the dominant structures of the flames. A recurrence analysis using the temperature time series data revealed significant differences in flame dynamics, including period-2 oscillations and intermittency, for different wall materials. The underlying physics behind the periodic oscillations and intermittent bursting has been explained.
Isotope study of the nonlinear pressure shifts of 85Rb and 87Rb hyperfine resonances in Ar, Kr, and Xe buffer gases
Authors: McGuyer B. H.
Published: April 2023

Measurements of the 0–0 hyperfine resonant frequencies of ground-state 85Rb atoms show a nonlinear dependence on the pressure of the buffer gases Ar, Kr, and Xe. The nonlinearities are similar to those previously observed with 87Rb and 133Cs and presumed to come from alkali-metal–noble-gas van der Waals molecules. However, the shape of the nonlinearity observed for Xe conflicts with previous theory, and the nonlinearities for Ar and Kr disagree with the expected isotopic scaling of previous 87Rb results. Improving the modeling alleviates most of these discrepancies by treating rotation quantum mechanically and considering additional spin interactions in the molecules. Including the dipolar-hyperfine interaction allows simultaneous fitting of the linear and nonlinear shifts of both 85Rb and 87Rb in either Ar, Kr, or Xe buffer gases with a minimal set of shared, isotope-independent parameters. To the limit of experimental accuracy, the shifts in He and N2 were linear with pressure. The results are of practical interest to vapor-cell atomic clocks and related devices.
Positioning of grid points for spanning potential energy surfaces—How much effort is really needed?
Authors: Schneider Moritz , Born Daniel , Kästner Johannes , Rauhut Guntram
Published: April 2023

The positions of grid points for representing a multidimensional potential energy surface (PES) have a non-negligible impact on its accuracy and the associated computational effort for its generation. Six different positioning schemes were studied for PESs represented by n-mode expansions as needed for the accurate calculation of anharmonic vibrational frequencies by means of vibrational configuration interaction theory. A static approach, which has successfully been used in many applications, and five adaptive schemes based on Gaussian process regression have been investigated with respect to the number of necessary grid points and the accuracy of the fundamental modes for a small set of test molecules. A comparison with a related, more sophisticated, and consistent approach by Christiansen et al. is provided. The impact of the positions of the ab initio grid points is discussed for multilevel PESs, for which the computational effort of the individual electronic structure calculations decreases for increasing orders of the n-mode expansion. As a result of that, the ultimate goal is not the maximal reduction of grid points but rather the computational cost, which is not directly related.
Electron-beam–controlled deflection of near-infrared laser in semiconductor plasma
Authors: Sakai Y. , Williams O. B. , Fukasawa A. , Murokh A. , Kupfer R. , Kusche K. , Fedurin M. , Pogorelsky I. , Polyanskiy M. , Babzien M. , Palmer M. , Rosenzweig J. B.
Published: April 2023

A timing method for experiments on the interaction of a near-infrared laser and an ultra-relativistic electron beam via a semiconductor plasma switch is experimentally validated. As an intermediate medium, a thin Si plate is excited by the energetic, intense electron beam to produce a semiconductor plasma, which in turn deflects counter-colliding laser light having 1 μm wavelength. An electron beam of sub-nC charge sufficiently induces the needed electron number density gradient of 1 × 1020 cm−3 per tens of μm length at the interaction point. Demonstration during an inverse Compton scattering experiment by a counter-colliding electron beam of 300 pC and 70 MeV with an Nd: YAG laser at a wavelength of 1 μm is reported.
Near-thermo-neutral electron recombination of titanium oxide ions
Authors: Jain Naman , Kálosi Ábel , Nuesslein Felix , Paul Daniel , Wilhelm Patrick , Ard Shaun G. , Grieser Manfred , von Hahn Robert , Heaven Michael C. , Miliordos Evangelos , Maffucci Dominique , Shuman Nicholas S. , Viggiano Albert A. , Wolf Andreas , Novotný Oldřich
Published: April 2023

While the dissociative recombination (DR) of ground-state molecular ions with low-energy free electrons is generally known to be exothermic, it has been predicted to be endothermic for a class of transition-metal oxide ions. To understand this unusual case, the electron recombination of titanium oxide ions (TiO+) with electrons has been experimentally investigated using the Cryogenic Storage Ring. In its low radiation field, the TiO+ ions relax internally to low rotational excitation (≲100 K). Under controlled collision energies down to ∼2 meV within the merged electron and ion beam configuration, fragment imaging has been applied to determine the kinetic energy released to Ti and O neutral reaction products. Detailed analysis of the fragment imaging data considering the reactant and product excitation channels reveals an endothermicity for the TiO+ dissociative electron recombination of (+4 ± 10) meV. This result improves the accuracy of the energy balance by a factor of 7 compared to that found indirectly from hitherto known molecular properties. Conversely, the present endothermicity yields improved dissociation energy values for D0(TiO) = (6.824 ± 0.010) eV and D0(TiO+) = (6.832 ± 0.010) eV. All thermochemistry values were compared to new coupled-cluster calculations and found to be in good agreement. Moreover, absolute rate coefficients for the electron recombination of rotationally relaxed ions have been measured, yielding an upper limit of 1 × 10−7 cm3 s−1 for typical conditions of cold astrophysical media. Strong variation of the DR rate with the TiO+ internal excitation is predicted. Furthermore, potential energy curves for TiO+ and TiO have been calculated using a multi-reference configuration interaction method to constrain quantum-dynamical paths driving the observed TiO+ electron recombination.
Effects of electrostatic coupling and surface polarization on polyelectrolyte brush structure
Authors: Telles Igor M. , Arfan Muhammad , dos Santos Alexandre P.
Published: April 2023

In this work, we perform molecular dynamics simulations to study a spherical polyelectrolyte brush. We explore the effects of surface polarization and electrostatic coupling on brush size and distribution of counterions. The method of image charges is considered to take into account surface polarization, considering a metallic, an unpolarizable, and a dielectric nano-core. It is observed that, for all cases, a moderate shrinking–swelling effect appears with an increase in the electrostatic coupling parameter. This effect occurs under high Manning ratios. The curves relating the average size of polyelectrolyte brush as a function of coupling show a minimum. The results show that the grafting density of polyelectrolytes on the nano-core surface plays an important role in the polarization effect. We consider a modified Poisson–Boltzmann theory to describe the counterion profiles around the brush in the case of unpolarizable nano-cores and weak electrostatic coupling.
A note on pressure and pressure-correction-based fractional-step approaches for low Reynolds number incompressible flows
Authors: Deka Mandeep
Published: April 2023

A comparative study on pressure and pressure-correction-based fractional-step methods for incompressible flows is presented. Implicit fractional-step methods are shown to give rise to a splitting error due to the implicit temporal discretization of the intermediate momentum equations. Through mathematical reasoning and a numerical example, a relative advantage of pressure-correction-based approaches over pressure-based approach for the computation of low Reynolds number flows using implicit fractional-step methods is demonstrated.
Embryo development and survival in peripubertal ewe lambs
Authors: Juengel Jennifer L. , Quirke Laurel D. , Peers-Adams Jacqui , Johnstone Peter D. , Smith Peter
Published: April 2023

Context Mating of ewe lambs can increase farm profitability, although uptake is limited by low reproductive success. Reproductive loss to Day 35 of pregnancy in peripubertal ewe lambs is greater than in adult ewes; however, the precise timing of this loss is unknown. Aim We aimed to define more clearly early embryo development and key times of loss in peripubertal ewes. Methods Health and development of embryos from naturally cycling crossbred ewes ~8 months of age were recorded. Following mating across 2 years, ewes were assigned to three groups (n = 80–87 per group): assessed on Day 3 of pregnancy, on Day 14, or between Day 35 and birth. For Day 3 and Day 14 groups, ewes were humanely killed, and embryos were assessed by microscope following recovery from the reproductive tract. Ultrasonography at around Days 35 and 70, and lambing data, were used to assess loss in the third group. Key results By Day 3 of pregnancy, 22.9% of ova released were not present as healthy embryos (P < 0.05). Embryo survival on Day 14 tended (P < 0.10) to decrease further, with 34.0% (±4.5%) of ova released not present as healthy embryos. No decrease was detected between Days 14 and 35, whereas between Day 35 and birth, an additional 6.8% reproductive loss occurred (P < 0.05). Attainment of puberty prior to introduction of the fertile ram did not affect reproductive loss. Structures collected on Day 3 ranged from one cell to 12 cells: 11% (13/120) being one cell; 49% (59/120) two to four cells; and the remainder (48/120) at least five or six cells. Conceptus length at Day 14 ranged from 5.3 to 200.0 mm, with large variation between and within animals; within-ewe variation was 67% of between-ewe variation. Concentration of progesterone at time of collection was associated (P < 0.001) with developmental stage on Day 3, but not Day 14, of pregnancy. Conclusions Reproductive loss in peripubertal ewes primarily occurred prior to Day 14, with much of this loss before Day 3. Implications Improving oocyte and oviduct quality is important to supporting normal fertilisation and early embryo development in peripubertal ewe lambs, thus improving reproductive success.
Reverse strain effects in the defect states in aluminium doped ZnO
Authors: Dash Ritambhara , Kumari Neha , Jana Soumita , Bhattacharyya A. S.
Published: April 2023

ZnO was synthesised by the sol–gel method using zinc nitrate as the precursor. ZnO was doped with Al. Stress in the lattice was evident from the XRD peak shifts. A higher concentration of Al+3 showed a reverse strain effect also causing a reverse effect in the optical properties. An increase in crystallite size due to increased Al+3 was observed. A variation in absorption intensity based on the defect energy levels was observed. A difference in energy of the emission and absorption spectra resulting from defects in the material and non-radiative decay was seen. A change in the band gap was observed with changes in different dopant concentrations. These findings are useful for photocatalytic as well as antibacterial and anticancer treatments.
Cauliflower-like strontium-doped SnO2 nanoparticles for photocatalytic degradation
Authors: Vallimeena S. , Helina B.
Published: April 2023

Three-dimensional (3D) cauliflower-shaped Strontium (Sr)-doped SnO2 nanoparticles were synthesised at ambient temperature through a simple co-precipitation technique. The 3D cauliflower-shaped 7 wt-% Sr-doped SnO2 nanoparticles increase light harvesting features and also promote electron transport across grain boundaries. 3D cauliflower-shaped Sr-doped SnO2 nanoparticles offer low charge transfer resistance, which is validated by the electrochemical impedance spectroscopy spectrum. XRD studies of SnO2 and Sr-doped SnO2 have revealed a tetragonal structure, and PL spectra corroborate the greater charge splitting. This study may be the first ever report on the 3D microstructure of cauliflower-shaped 7 wt-% Sr-doped SnO2 nanoparticles that demonstrated higher photocatalytic activity under visible-light for MB dye solution.
Understanding substrate-driven growth mechanism of copper silicide nanoforms and their applications
Authors: Sen Shashwati , Kanitkar Prajakta , Muthe K. P.
Published: April 2023

The growth mechanism of various nanoforms of copper/copper silicide on Si substrates with different orientations is reported here. The triangular, square and rectangular copper/copper silicide nanostructures are deposited on silicon substrates with (111), (100) and (110) orientations respectively, by thermal evaporation of metallic copper at different substrate temperatures. Investigations confirm that the nanostructures consist of a pure copper layer on top of a copper silicide layer. The morphology and growth behaviour studies confirmed for the first time that the formation of well-defined structures and shapes are governed by the Si substrate orientation and the surface reconstruction of the Si planes. The copper silicide nanostructures are used in field emission applications and also serve as a template for the growth of carbon nano-fibre.
GPI anchors: Regulated as needed
Authors: Aguilera-Romero Auxiliadora , Muñiz Manuel
Published: April 2023

GPI anchoring is an essential post-translational modification in eukaryotes that links proteins to the plasma membrane. In this issue, Liu et al. (2023. J. Cell Biol.https://doi.org/10.1083/jcb.202208159) suggest, for the first time, a regulation on demand of the GPI glycolipid precursor biosynthesis.
Generic features of a polymer quantum black hole
Authors: Münch Johannes , Perez Alejandro , Speziale Simone , Viollet Sami
Published: April 2023

Non-singular black holes models can be described by modified classical equations motivated by loop quantum gravity. We investigate what happens when the sine function typically used in the modification is replaced by an arbitrary bounded function, a generalization meant to study the effect of ambiguities such as the choice of representation of the holonomy. A number of features can be determined without committing to a specific choice of functions. We find generic singularity resolution. The presence and number of horizons is determined by global features of the function regularizing the angular components of the connection, and the presence and number of bounces by global features of the function regularizing the time component. The trapping or anti-trapping nature of regions inside horizons depends on the relative location with respect to eventual bounces. We use these results to comment on some of the ambiguities of polymer black hole models.
Tuning between composition and nanoparticle size of manganites for self-regulated magnetic hyperthermia applications
Authors: Caraballo-Vivas R J , Santos E C S , Valente-Rodrigues C L , Checca N R , Garcia F
Published: April 2023

Self-regulated magnetic hyperthermia is a promising alternative for cancer treatment based on tumor annihilation by heating using appropriate Curie temperature (

T

C

) as an internal temperature controller. We successfully prepared strontium-doped lanthanum manganite nanoparticles (LSMO-x) using the sol-gel method. The

T

C

can be adjusted by modifying both the composition and diameter of the particles, that is, varying the Sr content (0.2 

⩽
x
⩽

 0.3) and the annealing temperature (600 ∘C, 700 ∘C, and 800 ∘C). Structural, morphological, chemical, and magnetic properties were investigated. The samples exhibit the structure of perovskites with average particle sizes ranging from 17 nm to 27 nm, depending on the annealing temperature. This diameter range ensures that all samples investigated are have negligible remanence at room temperature. Magnetization studies show that

T

C

increases as Sr content and particle size increase, indicating that the

T

C

is governed by both. Thus

T

C

can be adjusted by combining these two parameters for self-regulated magnetic hyperthermia. Magnetic hyperthermia measurements showed that samples with larger particle sizes (

⩾

19 nm) were more efficient in promoting heat, that is, presenting a higher specific absorption rate (SAR), probably due to the adequate balance between the Néel and Brownian relaxations behavior. We figure out that the SAR value is essential for this specific finality, but it should also consider the maximum temperature reached during the hyperthermia essays. Finally, we build up a nanoparticle diameter vs. Sr concentration phase diagram, where the SAR values are displayed, which allows for predicting the best sample for the self-regulated hyperthermia.
A highly sensitive filterless narrowband 4H-SiC photodetector employing a charge narrowing strategy
Authors: Li Menghui , Geng Lulu , Xi Yuying , Hu Kun , Shi Linlin , Wang Wenyan , Tian Yuan , Ji Ting , Mao Kaili , Xu Bingshe , Li Guohui , Lu Hai , Cui Yanxia
Published: April 2023

Silicon carbide (SiC) semiconductors with a wide bandgap have attracted much attention because they can endure harsh environments and high temperatures. SiC photodetectors based on conventional principles usually detect ultraviolet (UV) light without the ability to discriminate wavelength. Here, using the charge narrowing collection principle, we realize a highly sensitive filterless narrowband 4H-SiC photodetector. The 4H-SiC layer is sufficiently thick to facilitate charge collection narrowing of the device’s external quantum efficiency spectrum, inducing a full width at half-maximum of 14.5 nm at the peak wavelength of 355 nm. Thanks to the Fermi level pinning effect, the proposed photodetector can fully eliminate the injection current; thus it works as a photovoltaic type device with a remarkably low dark current. Consequently, the device has a photo-to-dark current ratio as high as 4 × 107, superior to the performance of most reported 4H-SiC UV photodetectors. In addition, the device can detect light signals with a power density as low as 96.8 pW cm−2, more than two orders of magnitude superior to that of the commercial product based on the photodiode principle. Moreover, it can endure high temperatures of 350 °C, demonstrating bright prospects in harsh industrial conditions.
Structure of amorphous materials in the NASICON system Na

1+x

Ti2Si
x
P

3−x

O12
Authors: Mendes Da Silva Rita , Zeidler Anita , Bradtmüller Henrik , Eckert Hellmut , Fischer Henry E , Benmore Chris J , Salmon Philip S
Published: April 2023

The structure of glasses in the sodium (Na) super-ionic conductor (NASICON) system Na

1
+
x

Ti2Si
x
P

3
−
x

O12 with x = 0.8 and x = 1.0 was explored by combining neutron and high-energy x-ray diffraction with 29Si, 31P and 23Na solid-state nuclear magnetic resonance (NMR) spectroscopy. The 29Si magic angle spinning (MAS) NMR spectra reveal that the silica component remains fully polymerized in the form of Si4 units, i.e. the silicon atoms are bound to four bridging oxygen atoms. The 31P{23Na} rotational echo adiabatic passage double resonance (REAPDOR) NMR data suggest that the 31P MAS NMR line shape originates from four-coordinated P
n
units, where n = 1, 2 or 3 is the number of bridging oxygen atoms per phosphorus atom. These sites differ in their 31P-23Na dipolar coupling strengths. The results support an intermediate range order scenario of a phosphosilicate mixed network-former glass in which the phosphate groups selectively attract the Na+ modifier ions. Titanium takes a sub-octahedral coordination environment with a mean Ti–O coordination number of 5.17(4) for x = 0.8 and 4.86(4) for x = 1.0. A mismatch between the P–O and Si–O bond lengths of 8% is likely to inhibit the incorporation of silicon into the phosphorus sites of the NASICON crystal structure.
The evaluation of an on-site monitoring program for activity meter quality assurance with exemption-level sources
Authors: Feng Chen-Ju , Wu Chin-Hui , Lin Chin-Hsiung , Yuan Ming-Chen , Lee Shen-Hao , Huang David YC , Lin Jo-Yu , Chen Ying-Fang , Hsu Shih-Ming
Published: April 2023

This paper discusses the feasibility of a monitoring program for the quality assurance status of activity meters. We sent a questionnaire to clinical nuclear medicine departments of medical institutions, requesting information on their activity meters and quality assurance practices. On-site visits were conducted with exemption-level standard sources (Co-57, Cs-137 and Ba-133) for dose calibrators in nuclear medicine departments including physical inspection, accuracy and reproducibility. A method offering a quick check on the detection efficiency of the space dimension inside the activity meters was also introduced. For dose calibrator quality assurance, the daily checks had the highest implementation. However, annual checks and upon acceptance/after a repair check were reduced to 50% and 44%, respectively. The accuracy results of dose calibrators showed that all models exceeded the ±10% criteria with Co-57 and Cs-137 sources. The reproducibility results showed that some models exceeded the ±5% criteria with Co-57 and Cs-137 sources. The appropriate application of exemption-level standard sources considering the uncertainty that affects the measurement is discussed.
Effect of 3D laser point spacing on cement concrete crack width measurement
Authors: Yang Xinyi , Hui Bing , Lu Bin , Yuan Bobo , Li Yang
Published: April 2023

The objective of this paper is to examine the reliability of three-dimensional (3D) laser detection technology data density for crack width detection results of cement slabs. Four groups of cement concrete crack elevation data with a laser data density of 0.5–1.5 mm were obtained using an indoor 3D laser detection system, and 3D models were established. The nonlinear least squares method was applied to fit the fracture section, and the crack width was determined by the peak value analysis. The results demonstrate that the lateral spacing of laser points exerts a large impact on the mean and discrete degrees of cement concrete crack width detection results. The laser point spacing is positively correlated with crack identification errors. Insufficient laser accuracy leads to an overestimation of crack severity level and affects the accuracy of pavement damage condition evaluation. High-precision laser equipment exhibits certain reliability for detecting cement concrete crack width above 3 mm. In the actual pavement crack width detection process, the appropriate transverse spacing of laser points can be selected according to different error limit requirements to fulfill the requirements of both detection reliability and data processing efficiency. Suggestions for future research include expanding the experimental conditions, increasing the 3D laser point spacings, and selecting more road lanes and pavement materials to further examine the influential factors of pavement crack width measurement.
Research on detection method of Tubercle Bacilli based on the improved YOLOv5
Authors: Li Yonghong , Zhou Cheng , Zhao Zhiqiang , Li Laquan
Published: April 2023

In the field of medical imaging, the detection method of Tubercle Bacilli based on deep learning can overcome the shortcomings of traditional manual detection methods, such as large subjectivity, large workload, slow detection speed, and reduce the occurrence of false detection or missed detection under specific circumstances. However, due to the small target and complex background of Tubercle Bacilli, the detection results are still not accurate enough. In order to reduce the influence of sputum sample background on Tubercle Bacilli detection and improve the accuracy of the model for Tubercle Bacilli detection, a target detection algorithm YOLOv5-CTS based on YOLOv5 algorithm is proposed in this paper. The algorithm first integrates the CTR3 module at the bottom of Backbone of YOLOv5 network to obtain more high-quality feature information, which brings significant performance improvement to the model; then in the neck and head part, a hybrid model with the improved feature pyramid networks and the added large-scale detection layer is utilized to perform feature fusion and small target detection; finally, the SCYLLA-Intersection over Union loss function is integrated. The experimental results show that YOLOv5-CTS increases the mean average precision to 86.2% compared with the existing target detection algorithms for Tubercle Bacilli, such as Faster R-CNN, SSD and RetinaNet, etc, which shows the effectiveness of this method.
Presence and statistics of a discontinuous potential distribution in the plume of an electric propulsion hollow cathode
Authors: Meng Tianhang , Li Yingting , Ning Zhongxi , Yu Daren
Published: April 2023

The extraction voltage of an electric propulsion hollow cathode is mainly deposited in its plume region, and is usually believed to be proportional to the plasma oscillation amplitude. However, this was not the case in some recent results. To understand the reason for this, this study has measured the potential distribution and oscillation amplitude distribution in the plume of a hollow cathode, and checked whether the correlation between the two was affected by changing keeper materials and keeper biases. We found a discontinuous potential rise (‘step region’) in the middle of the plume, the voltage of which occupied over 40% of the total discharge voltage. The step region was sensitive to exterior electron emission, and could shift its location in a ∼18 mm range according to an increase/decrease of oscillation amplitude. However, its voltage remained almost unchanged and, as a result, the total extraction voltage remained constant regardless of amplitude changes. Statistics indicated that the step region was related to electron–electron non-equilibrium, with splitting and recombination between electron energy probability function multi-components, each at different flow states and trapping states. It was suspected that shockwaves and streaming instabilities were involved. Because the step region was accompanied by stronger oscillations and higher ion energies, inclusion of this plasma structure should be necessary to promote cathode test accuracy.
Point-like plasma-limited high-temperature terahertz laser discharge
Authors: Kubarev V V , Gorbachev Ya I , Shevchenko O A , Vodopyanov A V , Sidorov A V , Veselov A P
Published: April 2023

Various methods for limiting the plasma volume made it possible to produce a continuous point-like high-temperature terahertz discharge at the Novosibirsk free-electron laser (NovoFEL). When a krypton-nitrogen jet was injected into the focus of the NovoFEL radiation, as compressed as possible and having an average power of about 200 W, a spherical plasma with a diameter of 1 mm, temperature of 4–4.5 eV (46 000–52 000 K), and density of 3.5 × 1017 cm−3 was obtained. The ion composition of the plasma is represented mainly by triply and doubly ionized krypton atoms (Kr IV and Kr III). The absolute stability of the plasma, which tends to self-oscillate, is achieved through the use of a special negative optical feedback.
A review on recent advances in fabricating freestanding single-crystalline complex-oxide membranes and its applications
Authors: Ji Jongho , Park Sangwoo , Do Hagjai , Kum Hyun S
Published: April 2023

Complex-oxide materials are gaining a tremendous amount of interest in the semiconductor materials and device community as they hold many useful intrinsic physical properties such as ferro/piezoelectricity, pyroelectricity, ferromagnetism, as well as magnetostriction and other properties suitable for energy storage elements. Complex-oxides can also be complemented with conventional semiconductor-based devices or used by themselves to realize state-of-the-art electronic/photonic/quantum information devices. However, because complex-oxide materials have vastly different crystalline structures and lattice constant difference compared to conventional semiconductor devices (such as Si or III-V/III-N materials), integration of complex-oxides onto conventional semiconductor platforms has been difficult. Thus, there has been constant efforts to produce freestanding single-crystalline complex-oxide thin films such that these films can be transferred and integrated together with device platforms based on other materials. This review will provide a comprehensive review on single-crystalline complex-oxide membranes technology developed thus far: how they are synthesized, methods to release them from the substrate, and their outstanding properties and applications.
General N-soliton solutions to the two types of nonlocal Gerdjikov-Ivanov equations via Riemann-Hilbert problem
Authors: Yang Yingmin , Xia Tiecheng , Liu Tongshuai
Published: April 2023

This paper mainly makes use of the Riemann-Hilbert approach to solve the two types of nonlocal Gerdjikov-Ivanov equations derived by different nonlocal group reductions. The Riemann-Hilbert problem of the general Gerdjikov-Ivanov equation is constructed and the relations between the Riemann-Hilbert problems of the nonlocal Gerdjikov-Ivanov equations and the above Riemann-Hilbert problem are discussed in two parts. The general N-soliton solutions of the nonlocal Gerdjikov-Ivanov equations are acquired by solving the Riemann-Hilbert problems of the nonlocal equations under the reflectionless case and the matrix forms of the soliton solutions are given. In particular, the dynamics of the solutions are explored and the images of the general one-soliton solutions and two-soliton solutions of two types of nonlocal Gerdjikov-Ivanov equations are shown with the appropriate parameters.
TL defect center analysis and radiation shielding phenomenon In Ho3+: Pb(YB)2O7 composite glasses
Authors: Ashok Kallagadda , Francis E Daniel , Guntu Ravi Kumar
Published: April 2023

The aim of the ongoing research was to create resources that are mechanically durable, thermally luminous, and radiation-shielding. In this manner, we intended to synthesize lead borate glasses containing functional groups for yttrium and holmium. Ho2O3 doped glasses, which are typically used for luminescent purposes, will also be used to investigate the thermoluminescence characteristics under gamma radiation. XRD, SEM, EDX, and DTA techniques are used to examine the samples’ structure, chemical analysis, and thermal characteristics. To assess the samples’ micro-hardness, the test sample’s ultrasonic velocities are measured. The mass attenuation coefficient and order of radiation protection ability are shown by the radiation shielding characteristics of samples. It should be highlighted that Holmium ions alone are responsible for the variations in the shielding behavior of glasses. The TL characteristics of the samples were examined at gamma irradiation doses of 0, 10, and 25 kGy. Irradiation increases the TL Intensities that have been observed. The findings show that Ho2O3 is the only factor contributing to the TL phenomenon, and test samples exhibit substantial TL activity. Additionally, samples were examined using the DTA technique for changes in thermal stability. This also implies that changes in thermal stability are solely dependent on holmium concentration. Overall, the results showed that YPBH glasses are effective TL materials and strong radiation shielding resources with low thickness values.
Law of approach to saturation magnetization with structural and temperature variation in Ni–Zn ferrites
Authors: Devi Elangbam Chitra , Singh Shougaijam Dorendrajit
Published: April 2023

Ni–Zn ferrite of compositional formula Ni0.5Zn0.5Fe2O4 was prepared by co-precipitation method. The effect of heat treatment at 600 °C, 800 °C, 1000 °C and 1200 °C on their structures and hence magnetic properties were investigated. Their phase analysis and morphological studies was done using XRD, FTIR, FT-Raman and SEM-EDAX. Room temperature magnetization loops of the prepared materials were recorded up to a maximum applied field of 15 kOe to study the effect of structural variation on magnetic properties. Further, magnetization loops of Ni–Zn ferrite heated at 1200 °C were recorded at 150 K and 50 K to investigate the variation of magnetic properties at low temperatures. Law of approach to saturation magnetization was applied to all the magnetization curves under investigation. The fitted parameters reveal information on the processes of magnetization, anisotropy constant, and saturation magnetization of Ni–Zn ferrites. Law of approach to saturation magnetization in the form M = M

s
(1− b/H
2) + cH was also found to be successfully applicable to magnetization curves of all the prepared Ni–Zn ferrites in room temperature as well as low temperatures. Its application and significant results were also discussed in detailed.
Impact of Mg-doping on the structural, optical, and magnetic properties of CuO nanoparticles and their antibiofilm activity
Authors: Adnan Russul , Abdallah A M , Mezher M , Noun M , Khalil Mahmoud , Awad R
Published: April 2023

Doping in metal oxide systems is being chased by many researchers since it is enhancing their properties. In the present study, Cu1-xMgxO nanoparticles, capped with EDTA were synthesized by the chemical co-precipitation method, with x = 0.000, 0.005, 0.010, 0.015, and 0.020, and further characterized by different techniques. The impact of doping by Mg2+ ions on the structural, optical, and magnetic properties of CuO nanoparticles was investigated and the antibacterial activity of the synthesized nanoparticles was studied by antibiofilm screening. The x-ray Powder Diffraction (XRD) patterns show the formation of a pure CuO phase with a good incorporation of Mg-dopant into the CuO lattice due to the comparable ionic radii of Cu2+ and Mg2+ ions. The Mg-dopant increases the crystallite size from 25 nm (at x = 0.000) to 28.12 nm (at x = 0.020). The Transmission Electron Microscope (TEM) images reveal the effect of Mg-doping on the morphology of CuO nanoparticles by decreasing their agglomeration, resulting in more uniform spherical-shaped nanoparticles. Energy Dispersive x-ray (EDX) and x-ray Photoelectron Spectroscopy (XPS) confirm the purity and the successful development of Mg-doped CuO nanoparticles. The changes in the characteristic vibrational modes of CuO are studied by Raman spectra, upon Mg-doping. Furthermore, the optical properties explored by Ultraviolet-Visible (UV–vis) spectroscopy reveal a redshift of the absorption peaks of CuO nanoparticles due to the Mg-doping. The energy gap (Eg) is affected by Mg-doping, where its broadening is attributed to the quantum confinement effect in CuO. The magnetic properties were investigated by Vibrating Sample Magnetometer (VSM) at room temperature. Cu1-xMgxO nanoparticles have combined paramagnetic and weak ferromagnetic behaviors. Besides, Cu1-xMgxO nanoparticles exhibited significant antibiofilm effects. These results highlight the potential use of Mg-doped CuO nanoparticles as antibiofilm agents.
Stability of hairy black holes in shift-symmetric scalar-tensor theories via the effective field theory approach
Authors: Khoury Justin , Noumi Toshifumi , Trodden Mark , Wong Sam S.C.
Published: April 2023

Shift-symmetric Horndeski theories admit an interesting class of Schwarzschild-de Sitter black hole solutions exhibiting time-dependent scalar hair. The properties of these solutions may be studied via a bottom-up effective field theory (EFT) based on the background symmetries. This is in part possible by making use of a convenient coordinate choice — Lemaître-type coordinates — in which the profile of the Horndeski scalar field is linear in the relevant time coordinate. We construct this EFT, and use it to understand the stability of hairy black holes in shift-symmetric Horndeski theories, providing a set of constraints that the otherwise-free functions appearing in the Horndeski Lagrangian must satisfy in order to admit stable black hole solutions. The EFT is analyzed in the decoupling limit to understand potential sources of instability. We also perform a complete analysis of the EFT with odd-parity linear perturbations around general spherically symmetric space-time.
Probing virtual ALPs by precision phase measurements: time-varying magnetic field background
Authors: Sharifian Mohammad , Zarei Moslem , Abdi Mehdi , Peloso Marco , Matarrese Sabino
Published: April 2023

We propose an experimental scheme for detecting the effects of off-shell axion-like particles (ALPs) through optical cavities. In this proposed experiment, linearly polarized photons are pumped into an optical cavity where an external time-dependent magnetic field is present. The magnetic field mediates an interaction between the cavity photons and ALPs giving rise to a modification in the phase of the cavity photons. The time-dependent nature of the external magnetic field prompts a novel amplification effect which significantly enhances this phase modification. A detection scheme is then proposed to identify such axion-induced phase shifts. We find that the phase modification is considerably sensitive to the photon-ALPs coupling constants gaγγ
for the range of ALPs mass 3.1 μeV ⩽ ma
⩽ 44.4 μeV.
Uniform rate inflation
Authors: Lin Chia-Min
Published: April 2023

In this work, I consider an inflation model with a quadratic potential and a negative cosmological constant. An analytical solution of the equation of motion for the inflaton field is found without slow-roll approximation. The result is that the inflation field is rolling at a constant speed. The prediction for cosmological perturbation is calculated.
Optical fiber vibration sensor for bearing fault detection based on Sagnac interferometer
Authors: Yang Xu , Li XianGuo , Meng DeJun , Shi Jia , Miao ChangYun
Published: April 2023

Bearings are crucial components in mechanical equipment, and bearing failure is one of the reasons for mechanical equipment safety accidents. In this work, an optical fiber vibration sensor based on Sagnac interferometer (SI) is proposed and applied to bearing fault detection. The polarization-maintaining fiber (PMF) is spliced between two single-mode fibers (SMFs) to form a SMF-PMF-SMF (SPS) fiber structure, which is connected with a 3 dB coupler to form a SI based on SPS fiber structure. The mass block is fixed in the middle of the PMF. When the monitored surface or structure vibrates, the stress of PMF will change and the Sagnac interference spectrum will be shifted, so that the vibration can be measured. The fabrication technology of sensor based on 3D printing is studied, and the structural parameters of the sensor are optimized through experiments and theoretical analysis. A vibration detection system and a rolling bearing vibration test platform based on SI and fiber ring laser are built. The experimental results show that the relative error between the experimental and theoretical results of healthy and faulty bearings is less than 1.60%, and the fault detection of bearings is realized. Temperature cross-sensitivity and stability of the sensing system are analyzed. The sensor has the advantages of simple structure, easy fabrication, anti-interference, etc, and has wide application prospects in engineering, machinery, security and other fields.
New Geiger-Nuttall law for cluster radioactivity half-lives*
Authors: Qi Lin-Jing , Zhang Dong-Meng , Luo Song , He Biao , Wu Xi-Jun , Chen Xun , Li Xiao-Hua
Published: April 2023

In this study, derived from Balasubramaniam's formula [Phys. Rev. C 70, 017301 (2004)] and further considering the effect of the parent nucleus mass, blocking effect, and effect of reduced mass on cluster radioactivity half-lives, we propose a new Geiger-Nuttall law that is model-independent to systematically evaluate the half-lives of this process for 16 even-even nuclei and 10 odd-A nuclei. For comparison, a single universal curve for cluster radioactivity and α decay proposed by Poenaru [Phys. Rev. C 83, 014601 (2011)], a scaling law proposed by Horoi [J. Phys. G: Nucl. Part. Phys. 30, 945 (2004)], an extension of the Viola-Seaborg formula from α decay to cluster radioactivity proposed by Ren et al. [Phys. Rev. C 70, 034304 (2004)], a new semi-empirical formula for exotic cluster decay proposed by Balasubramaniam et al. [Phys. Rev. C 70, 017301 (2004)], and a unified formula for the half-lives of α decay and cluster radioactivity proposed by Ni et al. [Phys. Rev. C 78, 044310 (2008)] are also used. The calculated results of our new Geiger-Nuttall law are in good agreement with the experimental half-lives, with the least rms being 0.606, and are better than the compared values. Moreover, we extend this formula to predict the cluster radioactivity half-lives of 51 nuclei whose decay energies are energetically allowed or observed but not yet quantified in NUBASE2020.