bluuebunny/crossref_metadata_2025 huggingface dataset:
Impact of periodic vaccination in SEIRS seasonal model
Authors: Gabrick Enrique C. , Brugnago Eduardo L. , de Souza Silvio L. T. , Iarosz Kelly C. , Szezech José D. , Viana Ricardo L. , Caldas Iberê L. , Batista Antonio M. , Kurths Jürgen
Published: January 2024

We study three different strategies of vaccination in an SEIRS (Susceptible–Exposed–Infected–Recovered–Susceptible) seasonal forced model, which are (i) continuous vaccination; (ii) periodic short-time localized vaccination, and (iii) periodic pulsed width campaign. Considering the first strategy, we obtain an expression for the basic reproduction number and infer a minimum vaccination rate necessary to ensure the stability of the disease-free equilibrium (DFE) solution. In the second strategy, short duration pulses are added to a constant baseline vaccination rate. The pulse is applied according to the seasonal forcing phases. The best outcome is obtained by locating intensive immunization at inflection of the transmissivity curve. Therefore, a vaccination rate of 44.4% of susceptible individuals is enough to ensure DFE. For the third vaccination proposal, additionally to the amplitude, the pulses have a prolonged time width. We obtain a non-linear relationship between vaccination rates and the duration of the campaign. Our simulations show that the baseline rates, as well as the pulse duration, can substantially improve the vaccination campaign effectiveness. These findings are in agreement with our analytical expression. We show a relationship between the vaccination parameters and the accumulated number of infected individuals, over the years, and show the relevance of the immunization campaign annual reaching for controlling the infection spreading. Regarding the dynamical behavior of the model, our simulations show that chaotic and periodic solutions as well as bi-stable regions depend on the vaccination parameters range.
Achromatic, planar Fresnel-reflector for a single-beam magneto-optical trap
Authors: Bondza S. A. , Leopold T. , Schwarz R. , Lisdat C.
Published: January 2024

We present a novel achromatic, planar, periodic mirror structure for single-beam magneto-optical trapping and demonstrate its use in the first- and second-stage cooling and trapping for different isotopes of strontium. We refer to it as a Fresnel magneto-optical trap (MOT) as the structure is inspired by Fresnel lenses. By design, it avoids many of the problems that arise for multi-color cooling using planar structures based on diffraction gratings, which have been the dominant planar structures to be used for single-beam trapping thus far. In addition to a complex design process and cost-intensive fabrication, diffraction gratings suffer from their inherent chromaticity, which causes different axial displacements of trap volumes for different wavelengths and necessitates trade-offs in their diffraction properties and achievable trap depths. In contrast, the Fresnel-reflector structure presented here is a versatile, easy-to-manufacture device that combines achromatic beam steering with the advantages of a planar architecture. It enables miniaturizing trapping systems for alkaline-earth-like atoms with multiple cooling transitions as well as multi-species trapping in the ideal tetrahedral configuration and within the same volume above the structure. Our design presents a novel approach for the miniaturization of cold-atom systems based on single-beam MOTs and enables the widespread adoption of these systems.
First-principle study of spin transport property in L10-FePd(001)/graphene heterojunction
Authors: Adachi Hayato , Endo Ryusuke , Shinya Hikari , Naganuma Hiroshi , Ono Tomoya , Uemoto Mitsuharu
Published: January 2024

In our previous work, we synthesized a metal/2D material heterointerface consisting of L10-ordered iron–palladium (FePd) and graphene (Gr) called FePd(001)/Gr. This system has been explored by both experimental measurements and theoretical calculations. In this study, we focus on a heterojunction composed of FePd and multilayer graphene referred to as FePd(001)/m-Gr/FePd(001), where m represents the number of graphene layers. We perform first-principles calculations to predict their spin-dependent transport properties. The quantitative calculations of spin-resolved conductance and magnetoresistance (MR) ratio (150%–200%) suggest that the proposed structure can function as a magnetic tunnel junction in spintronics applications. We also find that an increase in m not only reduces conductance but also changes transport properties from the tunneling behavior to the graphite π-band-like behavior. Additionally, we investigate the spin-transfer torque-induced magnetization switching behavior of our junction structures using micromagnetic simulations. Furthermore, we examine the impact of lateral displacements (sliding) at the interface and find that the spin transport properties remain robust despite these changes; this is the advantage of two-dimensional material hetero-interfaces over traditional insulating barrier layers such as MgO.
Predicting dynamic stability from static features in power grid models using machine learning
Authors: Titz Maurizio , Kaiser Franz , Kruse Johannes , Witthaut Dirk
Published: January 2024

A reliable supply with electric power is vital for our society. Transmission line failures are among the biggest threats for power grid stability as they may lead to a splitting of the grid into mutual asynchronous fragments. New conceptual methods are needed to assess system stability that complement existing simulation models. In this article, we propose a combination of network science metrics and machine learning models to predict the risk of desynchronization events. Network science provides metrics for essential properties of transmission lines such as their redundancy or centrality. Machine learning models perform inherent feature selection and, thus, reveal key factors that determine network robustness and vulnerability. As a case study, we train and test such models on simulated data from several synthetic test grids. We find that the integrated models are capable of predicting desynchronization events after line failures with an average precision greater than 0.996 when averaging over all datasets. Learning transfer between different datasets is generally possible, at a slight loss of prediction performance. Our results suggest that power grid desynchronization is essentially governed by only a few network metrics that quantify the networks’ ability to reroute the flow without creating exceedingly high static line loadings.
Reaction coordinate flows for model reduction of molecular kinetics
Authors: Wu Hao , Noé Frank
Published: January 2024

In this work, we introduce a flow based machine learning approach called reaction coordinate (RC) flow for the discovery of low-dimensional kinetic models of molecular systems. The RC flow utilizes a normalizing flow to design the coordinate transformation and a Brownian dynamics model to approximate the kinetics of RC, where all model parameters can be estimated in a data-driven manner. In contrast to existing model reduction methods for molecular kinetics, RC flow offers a trainable and tractable model of reduced kinetics in continuous time and space due to the invertibility of the normalizing flow. Furthermore, the Brownian dynamics-based reduced kinetic model investigated in this work yields a readily discernible representation of metastable states within the phase space of the molecular system. Numerical experiments demonstrate how effectively the proposed method discovers interpretable and accurate low-dimensional representations of given full-state kinetics from simulations.
Periodic dynamics of optical skyrmion lattices driven by symmetry
Authors: Zhang Qiang , Yang Aiping , Xie Zhenwei , Shi Peng , Du Luping , Yuan Xiaocong
Published: January 2024

The recently developed concept of optical skyrmions has introduced an exciting dimension to the emerging field of Poincaré engineering in optical lattices. There remains an unexplored territory in investigating system geometries to enhance the versatility of manipulating the topological landscape within optical lattices. Here, we present both experimental and theoretical evidence showcasing the periodic vectorial characteristics of field- and spin-based skyrmion lattices, generated by plasmonic vortices with varying topological charges. Our findings reveal that the geometric symmetry of the system plays a pivotal role in governing the periodic arrangement of these vortex patterns. Building upon this arrangement, the orbital–orbital coupling of plasmonic vortices gives rise to densely packed energy flow distributions, intricately bonded to topological charges. Consequently, this results in the formation of sublattices within the momentum space, each characterized by distinct k-vectors. Skyrmion and meron topologies, driven by the intrinsic spin–orbital coupling, are presented in these lattices. This proposed framework illuminates how symmetry serves as a fundamental tool in the manipulation of optical lattice topologies, opening up new avenues in fields ranging from optical trapping, laser writing, quantum gas microscopy, to electron quantum state control, each of which is poised to benefit from these nontrivial advances.
Stability of nonlinear Dirac solitons under the action of external potential
Authors: Mellado-Alcedo David , Quintero Niurka R.
Published: January 2024

The instabilities observed in direct numerical simulations of the Gross–Neveu equation under linear and harmonic potentials are studied. The Lakoba algorithm, based on the method of characteristics, is performed to numerically obtain the two spinor components. We identify non-conservation of energy and charge in simulations with instabilities, and we find that all studied solitons are numerically stable, except the low-frequency solitons oscillating in the harmonic potential over long periods of time. These instabilities, as in the case of the Gross–Neveu equation without potential, can be removed by imposing absorbing boundary conditions. The dynamics of the soliton is in perfect agreement with the prediction obtained using an Ansatz with only two collective coordinates, namely, the position and momentum of the center of mass. We employ the temporal variation of both field energy and momentum to determine the evolution equations satisfied by the collective coordinates. By applying the same methodology, we also demonstrate the spurious character of the reported instabilities in the Alexeeva–Barashenkov–Saxena model under external potentials.
High-volume biological sample processing using microwaves
Authors: Wilson-Garner S. , Alzeer S. , Baillie L. , Porch A.
Published: January 2024

This paper describes the design and optimization of a 10 ml cartridge for patient sample processing using a 3.5 GHz (empty resonant frequency) TM010 cylindrical microwave cavity. The cartridge has been designed to augment a novel approach for the rapid diagnosis of M. tuberculosis (the causative agent of Ttuberculosis), which uses the direct application of microwaves to a bacteria-containing sample to release pathogen-specific DNA. The target bacterial DNA is then captured and recovered using magnetic nanoparticles coated with pathogen-specific DNA probes. Excitation parameters were optimized using three surrogates for M. tuberculosis, namely, M. smegmatis, M. abscessus, and M. bovis suspended in water and simulated sputum. The paper also explores the mechanism of microwave-mediated DNA release from bacteria using scanning electron microscopy. Examination of bacteria exposed to microwaves at power levels known to mediate the release of DNA reveals no obvious signs of permanent cell disruption, suggesting that a more subtle interaction is taking place. Finally, the presence of microwave-liberated M. bovis DNA was able to be detected at a level of sensitivity comparable to that achieved using microscopy.
A study of (2+1)-dimensional variable coefficients equation: Its oceanic solitons and localized wave solutions
Authors: Akinyemi Lanre , Manukure Solomon , Houwe Alphonse , Abbagari Souleymanou
Published: January 2024

In this work, shallow ocean-wave soliton, breather, and lump wave solutions, as well as the characteristics of interaction between the soliton and lump wave in a multi-dimensional nonlinear integrable equation with time-variable coefficients, are investigated. The Painlevé analysis is used to verify the integrability of this model. Based on the bilinear form of this model, we use the simplified Hirota's method obtained from the perturbation approach and various auxiliary functions to construct the aforementioned solutions. Besides, the interaction between the soliton and lump wave solutions is also examined. In addition, by imposing specific constraint conditions on the N-soliton solutions, we further derive higher-order breather solutions. To show the physical characteristics of this model, several graphical representations of the discovered solutions are established. These graphs show that the time-variable coefficients result in a variety of novel dynamic behaviors that differ significantly from those for integrable equations with constant coefficients. The acquired results are useful for the study of shallow water waves in fluid dynamics, marine engineering, nonlinear sciences, and ocean physics.
A novel apparent permeability model for shale considering the influence of multiple transport mechanisms
Authors: Chen Shuai , Peng Xulin
Published: January 2024

Changes in pore pressure during the extraction of shale gas lead to dynamic alterations in the pore structure and permeability, making it challenging to gain a comprehensive understanding of the flow behaviors of shale gas. The pore structure of shale is complex, with a variety of storage modes and gas transport processes constrained by a number of factors. For instance, when gas flows through a transport channel with a finite length, it is imperative to take into account the flow loss caused by the bending of inlet and outlet streamlines, prior models typically neglect the impact of end effects, resulting in an exaggerated estimation of the shale permeability. Furthermore, a decrease in pore pressure corresponds to an increase in the Knudsen number, resulting in the breakdown of the continuity assumption of the Navier–Stokes equation, this signifies the gradual shift of the transport regimes from continuum flow to other transport regimes. The gas flow process is nonlinear due to the alternating impact of multicomponent transport mechanisms and various microscale effects. In this paper, we presented a novel apparent permeability model for shale that incorporates the impact of real gas effect, end effects, transport regimes, adsorption, and effective stress. First, we assumed the channel for shale gas transport to be circular pore and calculated the viscosity under the influence of a real gas effect as well as the corresponding Knudsen number. Subsequently, building upon the foundation of the slip model, we introduce the influence of the end effects to establish a bulk phase permeability for shale, further considering the impact of surface diffusion. Then, the pore radius was quantified under the influences of adsorption and effective stress. Using the intrinsic correlation between permeability and pore radius as a bridge, a shale apparent permeability model was further derived. The model encompasses various transport regimes and microscale effects, replicating the gas flow behaviors in shale. The new model was verified through comparison with published experimental data and other theoretical models, while analyzing the evolution of apparent permeability. Additionally, this paper discusses the influence of various factors, including end effects, pore radius, internal swelling coefficient, sorption-induced strain, and model-related parameters on the shale apparent permeability.
Analyzing photoionization cross-sectional modulation in CdSe/CdS core–shell nanodots: Impact of strain and applied electric field
Authors: Ed-Dahmouny A. , Jaouane M. , Fakkahi A. , El-Bakkari K. , Arraoui R. , Azmi H. , Sali A. , Es-Sbai N.
Published: January 2024

The role of strain in material properties is well-established, serving as a tool for altering atomic positions and defect formation, adjusting electronic structures and lattice vibrations, and influencing phase transitions, physical characteristics, and chemical properties. In this study, we conducted theoretical calculations of the binding energy and photoionization cross section (PCS) within a spherical core/shell quantum dot (CSQD) for the different transitions between the ground state of a donor impurity and the four low-lying conduction band states. During our study, we employed the finite element method to determine the energy levels and wave functions of the system within the effective mass approximation. Subsequently, we investigated the changes in PCS and binding energy while varying shell width under the influence of an applied electric field, considering both cases with and without the effect of strain. The strain effect was incorporated based on Hooke's law, and we developed specific expressions and utilized the continuum linear elasticity mechanical model for a single spherically symmetric shell. The results demonstrate that the strain correction enhances the binding energy of the four low-lying energy levels, leading to a shift of the PCS peaks toward higher energies. Conversely, the application of an external electric field has varying effects depending on the specific transition being considered. We compared our theoretical results with available experimental data and found them to be in good agreement. The pronounced blue-shift and substantial enhancement in magnitude of PCS spectra concerning shell width, electric field, and strain make CSQDs highly promising candidates for applications in adjustable nano-optoelectronic devices.
Epitaxial growth of AgCrSe2 thin films by molecular beam epitaxy
Authors: Nanao Y. , Bigi C. , Rajan A. , Vinai G. , Dagur D. , King P. D. C.
Published: January 2024

AgCrS e 2 exhibits remarkably high ionic conduction, an inversion symmetry-breaking structural transition, and is host to complex non-colinear magnetic orders. Despite its attractive physical and chemical properties and its potential for technological applications, studies of this compound to date are focused almost exclusively on bulk samples. Here, we report the growth of AgCrSe2 thin films via molecular beam epitaxy. Single-orientated epitaxial growth was confirmed by x-ray diffraction, while resonant photoemission spectroscopy measurements indicate a consistent electronic structure as compared to bulk single crystals. We further demonstrate significant flexibility of the grain morphology and cation stoichiometry of this compound via control of the growth parameters, paving the way for the targeted engineering of the electronic and chemical properties of AgCrSe2 in thin-film form.
Capillary filling dynamics of polymer melts in a bicontinuous nanoporous scaffold
Authors: Kong Weiwei , Neuman Anastasia , Zhang Aria C. , Lee Daeyeon , Riggleman Robert A. , Composto Russell J.
Published: January 2024

Polymer infiltrated nanoporous gold is prepared by infiltrating polymer melts into a bicontinuous, nanoporous gold (NPG) scaffold. Polystyrene (PS) films with molecular weights (Mw) from 424 to 1133 kDa are infiltrated into a NPG scaffold (∼120 nm), with a pore radius (Rp) and pore volume fraction of 37.5 nm and 50%, respectively. The confinement ratios (Γ=RgRp) range from 0.47 to 0.77, suggesting that the polymers inside the pores are moderately confined. The time for PS to achieve 80% infiltration (τ80%) is determined using in situ spectroscopic ellipsometry at 150 °C. The kinetics of infiltration scales weaker with Mw, τ80%∝Mw1.30±0.20, than expected from bulk viscosity Mw3.4. Furthermore, the effective viscosity of the PS melt inside NPG, inferred from the Lucas–Washburn model, is reduced by more than one order of magnitude compared to the bulk. Molecular dynamics simulation results are in good agreement with experiments predicting scaling as Mw1.4. The reduced dependence of Mw and the enhanced kinetics of infiltration are attributed to a reduction in chain entanglement density during infiltration and a reduction in polymer–wall friction with increasing polymer molecular weight. Compared to the traditional approach involving adding discrete particles into the polymer matrix, these studies show that nanocomposites with higher loading can be readily prepared, and that kinetics of infiltration are faster due to polymer confinement inside pores. These films have potential as actuators when filled with stimuli-responsive polymers as well as polymer electrolyte and fuel cell membranes.
Bifurcation analysis of double cavity flows
Authors: Vashishtha Manas , Vinoth B. R.
Published: January 2024

The first few bifurcations in a two-dimensional incompressible double cavity flow are investigated using the linear stability analysis, the Floquet analysis, and the nonlinear direct numerical simulations (DNS). The prediction of the critical Reynolds number and the type of bifurcation (Hopf, pitchfork, inverse pitchfork, and Neimark–Sacker), which depend on cavity configuration, by the linear stability analysis and the Floquet analysis is consistent with nonlinear DNS. The nonlinear DNS results show that the state of the system passes through multiple intermediate (unstable) states before it reaches the stable attractor (heteroclinic chain), and the type of intermediate states depends on initial conditions. The intermediate states are reported as the asymptotic state in the literature for some flow conditions because it is not known a priori how long it will take to reach the asymptotic state in nonlinear simulations. The present study reports the actual asymptotic state for those flow conditions.
Microgel particle deposition patterns after impinging on nanofiber-based coatings
Authors: Piskunova Alexandra , Khomutov Nikita , Piskunov Maxim
Published: January 2024

The study focuses on predicting the hydrodynamics of sodium alginate-based microgel “liquid core–gel shell” particles for droplet-based bioprinting. Hydrophobic polytetrafluoroethylene nanofiber-based coating (NBC #1) and hydrophilic polycaprolactone–polyvinylpyrrolidone NBC #2 are manufactured to serve as the basis for microgel deposition. An approach is proposed to model the flow of a Maxwell gel-like liquid with different fluidity, surface tension, and initial velocity along an inhomogeneous interface after microgel particle–NBC collision. Wetting and anti-wetting pressure differences allow estimating liquid impalement into NBCs at We = 10–50. For NBC #2, the initial particle velocity plays mainly a decisive role in predicting the contact diameter and height at maximum spreading and receding. For NBC #1, the pinning is considered by introducing the complex parameter resolving particle inertia, microgel rheology and surface tension, and NBC characteristics. The flow along the porous interface physically correlates with the extended Freundlich model, explaining the surface inhomogeneity caused by multilayer adsorption.
Switching jitter of avalanche gallium arsenide photoconductive semiconductor switch influenced by multiple avalanche domains
Authors: Chen Hong , Wei Jinhong , Sun Quan , Wang Langning , Li Song
Published: January 2024

The stability of synchronous operation is directly related to the time jitter of the gallium arsenide photoconductive semiconductor switch (GaAs PCSS). In this work, a numerical model for the switching jitter of avalanche GaAs PCSS is established, and the impacts of triggering optical energy and bias electric field on the switching jitter are investigated numerically based on an equivalent bulk current channel. The proposed numerical model predicts well the changing characteristics of switching time as well as switching jitter, which has been demonstrated by the experimental results. On this basis, the theory of multiple avalanche domains is introduced to compare the domain evolutions influenced by the bias electric field and triggering optical energy. The results indicate that the reduction of switching jitter is significantly determined by the accelerated formation and evolution of avalanche domains, which provides a good explanation of the jitter mechanism of switching time.
Using selective-area growth and selective-area etching on (−102) β-Ga2O3 substrates to fabricate plasma-damage-free vertical fins and trenches
Authors: Oshima Takayoshi , Oshima Yuichi
Published: January 2024

We have demonstrated selective-area growth and selective-area etching on SiO2-masked (−102) β-Ga2O3 substrates using a HCl-based halide-vapor-phase epitaxy system that is capable of performing both growth and gas etching without plasma excitation. Since the surface of the (−102) substrate is perpendicular to the (100) plane, which has the lowest surface energy, we were able to use both methods to fabricate plasma-damage-free fins and trenches with (100)-faceted vertical sidewalls on windows striped along the [010] direction with high processing accuracy. Furthermore, since the [010] window direction is aligned parallel to the majority of dislocations and line-shaped voids in the substrate—which extend along the [010] direction and could potentially act as leakage paths—such crystal defects are unlikely to appear on the surfaces of the resulting fins and trenches. We believe that these selective-area growth/etching techniques can greatly accelerate research on, and the development of, β-Ga2O3-based vertical/lateral devices with fins or trenches.
On the importance of Akhiezer damping to thermal conductivity in silicon at elevated temperatures above 300 K
Authors: Jin Jae Sik
Published: January 2024

Recently, Chiloyan et al. [Appl. Phys. Lett. 116, 163102 (2020)] have reported that phonon transport could exceed bulk heat conduction if low-frequency phonons with long mean free path (MFP) remain in the nonthermal regime in silicon. To gain a better understanding of their findings, we investigated the effects of temperature-induced anharmonicity on both Landau–Rumer damping and Akhiezer damping, including polarization. To do this, we follow a rigorous procedure for calculating the Akhiezer model and use phonon kinetic theory based on the Boltzmann transport equation. Consequently, we find that in the Akhiezer regime, the longitudinal acoustic phonon modes (LA) are strongly suppressed by phonon anharmonicity compared to the transverse acoustic phonon modes. Therefore, the low-frequency phonons with a long MFP of LA can help to exceed bulk heat conduction if they remain in the regime of nonthermal phonon transport where there are no appreciable scatterings with other phonons. It is also shown that Akhiezer damping eliminates thermal conductivity by 16.8% at 500 K, which is higher than the observed reduction (12.6%) at 300 K in silicon, uncovering a novel regime where the Akhiezer damping, previously deemed insignificant in the thermal conduction of bulk silicon, becomes crucial.
Machine learning for rapid discovery of laminar flow channel wall modifications that enhance heat transfer
Authors: Koide Yuri , Kaithakkal Arjun J. , Schniewind Matthias , Ladewig Bradley P. , Stroh Alexander , Friederich Pascal
Published: January 2024

Numerical simulation of fluid flow plays an essential role in modeling many physical phenomena, which enables technological advancements, contributes to sustainable practices, and expands our understanding of various natural and engineered systems. The calculation of heat transfer in fluid flow in simple flat channels is a relatively easy task for various simulation methods. However, once the channel geometry becomes more complex, numerical simulations become a bottleneck in optimizing wall geometries. We present a combination of accurate numerical simulations of arbitrary, flat, and non-flat channels as well as machine learning models trained on simulated data to predict the drag coefficient and Stanton number. We show that convolutional neural networks (CNNs) can accurately predict target properties at a fraction of the computational cost of numerical simulations. We use CNN models in a virtual high-throughput screening approach to explore a large number of possible, randomly generated wall architectures. Data augmentation techniques are incorporated to enforce physical invariances toward shifting and flipping, contributing to precise prediction for fluid flow and heat transfer characteristics. Moreover, we approach the interpretation of the trained model to better understand relevant channel structures and their influence on heat transfer. The general approach is not only applicable to simple flow setups as presented here but can be extended to more complex tasks, such as multiphase or even reactive unit operations in chemical engineering.
Research on ionization characteristics of atmospheric pressure pulse-modulated microwave He/air plasma jet
Authors: Zhang Lu , Chen Zhaoquan , Chu Binbin , Wang Xueliang , Bao Denghui , Chen Sile , Wang Chao , Lu Xinpei
Published: January 2024

The atmospheric pressure pulsed microwave He plasma jet has the advantages of high electron density and abundant active particles, but its shrinking on the discharge electrode morphology limits its application range. In order to modulate a He plasma jet with a longer plume and study its ionization development characteristics, we constructed a dual-channel pulsed microwave coaxial discharge device. He and air were, respectively, injected into the inner and outer gas channels of the resonator to generate a double-layer atmospheric pressure microwave plasma jet with a longer plume. It is observed that the bifurcation of the stratified plasma jet will occur by changing the gas flow. The ionization development of plasma jet was observed by using enhanced charge-coupled device and microwave Rayleigh scattering apparatus measured the space-time evolution of plasma and observed the three times ionization enhancement process of plasma jet development. The spectral lines of the active products associated with Penning ionization were observed by using a fiber optic spectrometer. A fluid model was constructed to simulate and analyze that under the condition of sufficient He flow rate (He flow rate is above 0.6 slm), there will be sufficient and stable He mole fraction (64%) at the stratification of the plasma jet. The experimental and simulation results show that the jet profile of the microwave He plasma is related to the inlet structure of the discharger and He flow rate. Stratified intake structure can produce stratified He plasma jet, and the unique appearance of bifurcation of jet can be produced by changing the flow rate of He. In the bifurcation process of the plasma jet, the product of Penning ionization inhibits the development of the main branch of the plasma jet, and the secondary electron avalanche of the local electric field promotes the formation of the branch of the plasma jet and is accompanied by the enhancement of the second ionization. The ionization mechanism of microwave He plasma is the resonance excitation of local enhanced electric field, the advance of ionizing waves, and the interaction between the spatially distributed active particles.
Realization of tunable-performance in atomic layer deposited Hf-doped In2O3 thin film transistor via oxygen vacancy modulation
Authors: Zhu Jiyuan , Hu Shen , Chen Bojia , Wei Shice , Zhang Yu , Wu Xuefeng , Zou Xingli , Lu Xionggang , Sun Qingqing , Zhang David W. , Ji Li
Published: January 2024

Due to the limitation of inherent ultra-high electron concentration, the electrical properties of In2O3 resemble those of conductors rather than semiconductors prior to special treatment. In this study, the effect of various annealing treatments on the microstructure, optical properties, and oxygen vacancies of the films and transistors is systematically investigated. Our finding reveals a progressive crystallization trend in the films with increasing annealing temperature. In addition, a higher annealing temperature is also associated with the reduction in the concentration of oxygen vacancies, as well as an elevation in both optical transmittance and optical bandgap. Furthermore, with the implementation of annealing process, the devices gradually transform from no pronounced gate control to exhibit with excellent gate control and electrical performances. The atomic layer deposited Hf-doped In2O3 thin film transistor annealed at 250 °C exhibits optimal electrical properties, with a field-effect mobility of 18.65 cm2 V−1 s−1, a subthreshold swing of 0.18 V/dec, and an Ion/Ioff ratio of 2.76 × 106. The results indicate that the impact of varying annealing temperatures can be attributed to the modulation of oxygen vacancies within the films. This work serves as a complementary study for the existing post-treatment of oxide films and provides a reliable reference for utilization of the annealing process in practical applications.
Deep neural network for learning wave scattering and interference of underwater acoustics
Authors: Mallik Wrik , Jaiman Rajeev , Jelovica Jasmin
Published: January 2024

It is challenging to construct generalized physical models of underwater wave propagation owing to their complex physics and widely varying environmental parameters and dynamical scales. In this article, we present a deep convolutional recurrent autoencoder network (CRAN) for data-driven learning of complex underwater wave scattering and interference. We specifically consider the dynamics of underwater acoustic scattering from various non-uniform seamount shapes leading to complex wave interference patterns of back-scattered and forward-propagated waves. The CRAN consists of a convolutional autoencoder for learning low-dimensional system representation and a long short-term memory (LSTM)-based recurrent neural network for predicting system evolution in low dimensions. The convolutional autoencoder enables efficient dimension reduction of wave propagation by independently learning global and localized wave features. To improve the time horizon of wave dynamics prediction, we introduce an LSTM architecture with a single-shot learning mechanism and optimal time-delayed data embedding. On training the CRAN over 30 cases containing various seamount geometries and acoustic source frequencies, we can predict wave propagation up to a time horizon of 5 times the initiation sequence length for 15 out-of-training cases with a mean L2 error of approximately 10%. For selected out-of-training cases, the prediction time horizon could be increased to 6 times the initiation sequence length. Importantly, such predictions are obtained with physically consistent wave scattering and wave interference patterns and at 50% lower L2 error compared to routinely use standard LSTMs. These results demonstrate the potential of employing such deep neural networks for learning complex underwater ocean acoustic propagation physics.
Improving oil and gas flowability in tight carbonates with a novel solid delayed acid
Authors: Wang Qing , Zhou Fujian , Yang Dandan , Yu Sen , Fei Hongtao , Yao Erdong , Chen Zhangxin
Published: January 2024

The economic development of tight carbonate reservoirs requires hydraulic or acid fracturing stimulation. Acid fracturing better activates natural fractures, resulting in increased stimulated reservoir volume and improving oil and gas flowability. In order to solve the problem of excessive acid-rock reaction due to high temperature, this paper screened four kinds of solid forms of acid with the maximum quantity of acid and reaction rate as the index and formed a high temperature-resistant mixed solid acid system with solid organic acid as the main part and inorganic solid acid as the auxiliary part. The maximum quantity of acid produced and effective acid concentration of the system were greater than 50%, and no residue was precipitated after the complete reaction. Dynamic acid-rock rate tests were performed on different types of retarded acid at 140 °C. The test results show that the solid acid dissolves to form a low-viscosity acid solution, and the reaction rate is one order of magnitude lower than that of gelled and cross-linked acids at the same hydrogen ion concentration, and it is little affected by temperature. Moreover, the paper compares the treatment effect of micro-proppants and solid acids on micro-fractures. The results show that the core permeability improvement multiples up to 900 times under low dissolution of solid acid and the formation of oil and gas flow channels with the same scale as micro-proppants. The experimental results demonstrated the ability of solid delayed acid to transport the fracture leading edge at high temperatures and effectively activate micro-fractures.
Scaling laws for natural convection boundary layer of a Pr
> 1 fluid on a vertical solid surface subject to a sinusoidal temperature in a linearly-stratified ambient fluid
Authors: Lin Wenxian , Armfield S. W. , Khatamifar Mehdi
Published: January 2024

The understanding of the transient behavior of natural convection boundary layer (NCBL) on a heated vertical solid surface under various heating conditions is of fundamental significance and application importance. In this study, scalings for the parameters representing the behavior of unsteady NCBL flow of a linearly-stratified Pr > 1 fluid on a semi-infinite vertical solid surface heated with a time-varying sinusoidal temperature at different development stages are developed with a scaling analysis, in terms of Ra, Pr, s, and fn, which are the Rayleigh number, Prandtl number, stratification number, and frequency of the sinusoidal temperature, respectively. These scalings are validated and quantified with a series of numerical simulations over wide ranges of Ra, Pr, s, and fn. The frequency of the fluctuations experienced by the NCBL behavior at the transitional stage, due to the stratification of the ambient fluid, is also analyzed, and it is shown that the previously obtained scaling for the unsteady NCBL case with the constant heat flux heating condition is basically applicable for the current case, Ra and fn have additional effects as well due to the time-varying nature of the applied temperature.
Structure of
Escherichia coli
exonuclease VII
Authors: Liu Chuan , Hauk Glenn , Yan Qianyun , Berger James M.
Published: January 2024

Exonuclease VII (ExoVII) is a ubiquitous bacterial nuclease. Encoded by the
xseA
and
xseB
genes, ExoVII participates in multiple nucleic acid–dependent pathways including the processing of multicopy single-stranded DNA and the repair of covalent DNA–protein crosslinks (DPCs). Although many biochemical properties of ExoVII have been defined, little is known about its structure/function relationships. Here, we use cryoelectron microscopy (cryoEM) to determine that
Escherichia coli
ExoVII comprises a highly elongated XseA
4
·XseB
24
holo-complex. Each XseA subunit dimerizes through a central extended α-helical segment decorated by six XseB subunits and a C-terminal, domain-swapped β-barrel element; two XseA
2
·XseB
12
subcomplexes further associate using N-terminal OB (oligonucleotide/oligosaccharide-binding) folds and catalytic domains to form a spindle-shaped, catenated octaicosamer. The catalytic domains of XseA, which adopt a nuclease fold related to 3-dehydroquinate dehydratases, are sequestered in the center of the complex and accessible only through large pores formed between XseA tetramers. The architectural organization of ExoVII, combined with biochemical studies, indicate that substrate selectivity is controlled by steric access to its nuclease elements and that tetramer dissociation results from substrate DNA binding. Despite a lack of sequence and fold homology, the physical organization of ExoVII is reminiscent of Mre11·Rad50/SbcCD ATP (adenosine triphosphate)-dependent nucleases used in the repair of double-stranded DNA breaks, including those formed by DPCs through aberrant topoisomerase activity, suggesting that there may have been convergent evolutionary pressure to contend with such damage events.
Hawker Centres, Cultural Heritage and Tourism – A Case Study of Lau Pa Sat, Singapore
Authors: Wang Lan
Published: January 2024

In the dynamic matrix of urban development, the conservation of heritage sites and the imperative of modernisation often find itself at a challenging nexus. This case study delves into the intricate interplay between urban heritage conservation and contemporary socio-economic demands, using the transformative narrative of Lau Pa Sat, Singapore, as a focal case. Drawing upon the dual paradigms of “use value” and “exchange value”, the research underscores the potential of heritage sites to both conserve cultural memory and catalyse modern economic revitalisation. Lau Pa Sat’s adaptive repurposing from a historical edifice to a dynamic hawker hub exemplifies a successful synthesis of architectural preservation and entrepreneurial initiative. Such an approach ensures the site’s functional sustainability while amplifying its cultural resonance. The research further highlights the significance of multi-stakeholder participation in rejuvenating urban memory through visual representation, communal spaces, and cultural paradigms. The findings underscore that, with strategic planning and community engagement, heritage sites can transcend historical confines, emerging as vibrant spaces that harmonise cultural conservation with contemporary relevance. This study provides invaluable insights for urban planners, policy makers, and heritage management professionals, advocating for a holistic approach that balances cultural stewardship with economic imperatives in urban heritage contexts.

Information

© The Author 2024
Dural mural cells paint an anti-inflammatory picture
Authors: Lummis Nicole C. , Gastfriend Benjamin D. , Daneman Richard
Published: January 2024

Mural cells directly contact macrophages in the dural layer of the meninges to suppress pro-inflammatory phenotypes, including antigen presentation and lymphocyte differentiation. These mechanisms represent new targets for modulating CNS immune surveillance and pathological inflammation (Min et al. 2024. J. Exp. Med.https://doi.org/10.1084/jem.20230326).
Key comparison BIPM.RI(I)-K5 of the air-kerma standards of the BEV, Austria and the BIPM in 137Cs gamma radiation
Authors: Kessler C , Roger P , Steurer A , Tiefenboeck W , Doria J
Published: January 2024

Main text

A new comparison of the standards for air kerma of the Bundesamt für Eich- und Vermessungswesen (BEV), Austria, and of the Bureau International des Poids et Mesures (BIPM) was carried out in the 137Cs radiation beam using the radiation protection facility of the International Atomic Energy Agency (IAEA) in Seibersdof, Austria in April 2023. The comparison was done using the BEV and the BIPM primary standards and a transfer instrument belonging to the BEV. The direct comparison result, evaluated as a ratio of the BEV and the BIPM standards for air kerma, is 1.0043 with a combined standard uncertainty of 2.7 parts in 103. The result for the indirect comparison is in agreement with the direct result at the level of 3 parts in 104. The results are analysed and presented in terms of degrees of equivalence, suitable for entry in the BIPM key comparison database, to update the 2009 comparison result.

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

The final report has been peer-reviewed and approved for publication by the CCRI, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).
The decay curves of luminescence from Eu2+ in β-SiAlON are effectively analyzed using the general-order kinetics formula
Authors: Suda Yoriko , Okuno Tsuyoshi , Takeda Takashi , Takahashi Kohsei , Hirosaki Naoto
Published: January 2024

Defects in phosphors affect not only luminescence intensity but also emission peak width, decay time, and afterglow. The green phosphor β-SiAlON:Eu2+ exhibits the green emission of Eu2+ at 520 nm and the blue emission of nitrogen vacancies at 460 nm in time-resolved fluorescence measurements. The decay time of the intrinsic Eu2+ transition is 0.7 μs, but afterglow is detected from 50 μs to 0.01 s. This afterglow decay curve is the same for the green emission of Eu2+ and the blue emission of nitrogen vacancies, suggesting that the defect levels of the nitrogen vacancies affect the Eu2+ transition. The afterglow decay curves were analyzed using the formula of the general-order kinetics,

1
+
t

/

τ

B

−
n

, where

n

is the decay power and

τ

B

is the decay time. This equation is generally used when analyzing afterglow on the order of seconds to hours but has not been examined systematically applied in samples with different concentrations of Eu2+ and temperatures on the order of nanoseconds to milliseconds. The decay power

n

is approximately 1 for all Eu2+ concentrations (x = 0.001–0.3) and undoped β-SiAlON. The decay time

τ

B

is correlated with the density of the nitrogen vacancies determined by electron spin resonance. Furthermore, the value of

n

is approximately 1 for 50 μs to 0.01 s and 0.3 for 1–1000 s. Thus, the luminescence mechanism of Eu2+ can be discussed by comparing

n

and

τ

B

obtained from the decay curves. In addition, several different Eu2+-doped phosphors, namely SrAl2O4:Eu2+, Dy3+, CaAlSiN3:Eu2+, and CaS:Eu2+, Tm3+, are studied.
Influence of light neutron-rich exotic nuclei in deciding abundance patterns relevant for explosive nucleosynthesis
Authors: Barman J , Sarkar S , Chatterjee R
Published: January 2024

Exotic neutron-rich nuclei play an important role in r-process nucleosynthesis. We study the effect of including proper nuclear structure to calculate neutron capture and photodisintegration rates, especially for 19C and 20N, under the aegis of post-form distorted wave Born approximation (FRDWBA). Considering a network of neutron-rich C–N–O isotopes, we show the effect on abundance calculations in a neutrino-driven wind environment of a core-collapse supernova at two critical temperatures T
9 = 3.4 and 0.62. The results are compared for nuclear physics inputs sourced from the FRDWBA, statistical estimates, and standard databases. At temperatures T
9 = 3.4, where alpha capture, or at T
9 = 0.62, where the neutron capture dominates, one can distinguish the effect of accounting for the exotic nature of the nuclei involved. Furthermore, we assess the impact of varying neutron capture and photodisintegration rates involving halo or bubble structures on the abundances within the network.
tt¯H
Interactions and T-odd Correlations at Hadron Colliders
Authors: Tiwari Apurba , Gupta Sudhir Kumar
Published: January 2024

We explore

C
P

-violation effects of Higgs-top interactions in the associated production of a Higgs boson with top-pair in the dileptonic decay modes of top-quark originating from proton proton collisions

pp
→
t

t
¯

H
→
(

l
+

ν
l

b
)
(

l
−

ν
l

¯

b
¯

)
H

at NLO in QCD matched to parton shower via T-odd observables using momenta of various particles involved in the process. In particular, we predict the constraints on the

C
P

-violating

t

t
¯

H

coupling obtained through the production asymmetries associated with the T-odd observables in the dileptonic decay channel of the

t

t
¯

pair for the Large hadron collider (LHC) with centre-of-mass energy of 13 TeV and an integrated luminosity of 139 fb−1. We also present the corresponding limits for future hadron colliders, namely the High Luminosity LHC (HL-LHC) and the Future Circular Collider (FCC-hh). Our estimates of the

t

t

¯

H

interaction strength reveal that the upper bound on pseudoscalar coupling c

p
corresponding to the largest asymmetry would be of about 1.57 × 10−2 at 2σ C.L. for c

s
= 1 at the LHC with

S

=13 TeV for an integrated luminosity of 139 fb−1. The respective limits for HL-LHC and FCC-hh with the projected Luminosities of 3 ab−1 and 30 ab−1 are found to be to 2.7 × 10−3 and 1.3 × 10−4 respectively at 2σ C.L.