bluuebunny/crossref_metadata_2025 huggingface dataset:
Modeling the performance and bandwidth of single-atom adiabatic quantum memories
Authors: Nateeboon Takla , Cholsuk Chanaprom , Vogl Tobias , Suwanna Sujin
Published: April 2024

Quantum memories are essential for quantum repeaters, which will form the backbone of the future quantum internet. Such memory can capture a signal state for a controllable amount of time, after which this state can be retrieved. In this work, we theoretically investigated how atomic material and engineering parameters affect the performance and bandwidth of a quantum memory. We have applied a theoretical model for quantum memory operation based on the Lindblad master equation and adiabatic quantum state manipulation. The materials’ properties and their uncertainty are evaluated to determine the performance of Raman-type quantum memories by showcasing two defects in two-dimensional hexagonal boron nitride. We have derived a scheme to calculate the signal bandwidth based on the material parameters as well as the maximum efficiency that can be realized. The bandwidth depends on four factors: the signal photon frequency, the dipole transition moments in the electronic structure, the cavity volume, and the strength of the external control electric field. As our scheme is general and independent of materials, it can be applied to many other quantum materials with a suitable three-level structure. We, therefore, provided a promising route for designing and selecting materials for quantum memories. Our work is, therefore, an important step toward the realization of a large-scale quantum network.
Restricted global optimization for QAOA
Authors: Gleißner Peter , Kruse Georg , Roßkopf Andreas
Published: April 2024

The Quantum Approximate Optimization Algorithm (QAOA) has emerged as a promising variational quantum algorithm for addressing NP-hard combinatorial optimization problems. However, a significant limitation lies in optimizing its classical parameters, which is in itself an NP-hard problem. To circumvent this obstacle, initialization heuristics, enhanced problem encodings and beneficial problem scalings have been proposed. While such strategies further improve QAOA’s performance, their remaining problem is the sole utilization of local optimizers. We show that local optimization methods are inherently inadequate within the complex cost landscape of QAOA. Instead, global optimization techniques greatly improve QAOA’s performance across diverse problem instances. While global optimization generally requires high numbers of function evaluations, we demonstrate how restricted global optimizers still show better performance without requiring an exceeding amount of function evaluations.
Verification of a Monte Carlo binary collision model for simulating elastic and inelastic collisions in particle-in-cell simulations
Authors: Lavell M. J. , Kish A. J. , Sexton A. T. , Masti R. L. , Mohammad I. , Kim M. J. , Srinivasan A. , Jarvis K. , Scullin W. , Shaw J. G. , Sefkow A. B.
Published: April 2024

We present the development and verification of a Monte Carlo binary collision model for simulating elastic and inelastic collisions in particle-in-cell simulations. We apply the corrected binary collision model originally developed for charged-particles collisions to all considered scattering channels, including Coulomb collisions, elastic neutral–neutral and charged–neutral collisions, ionization, excitation, and fusion. The model's implementation is described and verified through a series of simulations, including charged- and neutral-particle thermal equilibration, slowing of electrons in warm solid-density aluminum, collisional damping of a Langmuir wave, helium gas breakdown in an applied electric field, and thermonuclear and beam–target fusion. Then, we demonstrate the model within simulations of hydrogen plasma formation in the Princeton Field-Reversed Configuration as well as of the burning of aneutronic fusion fuel p-11B. The latter includes measurement of the fusion power density in a low-density plasma and fusion production due to the stopping of a proton ignitor beam in a compressed boron target.
Statistical analysis of high-frequency whistler waves at Earth's bow shock: Further support for stochastic shock drift acceleration
Authors: Amano Takanobu , Masuda Miki , Oka Mitsuo , Kitamura Naritoshi , Le Contel Olivier , Gershman Daniel J.
Published: April 2024

We statistically investigate high-frequency whistler waves (with frequencies higher than ∼10% of the local electron cyclotron frequency) at Earth's bow shock using magnetospheric multi-scale (MMS) spacecraft observations. We focus specifically on the wave power within the shock transition layer, where we expect electron acceleration via stochastic shock drift acceleration (SSDA) to occur associated with efficient pitch-angle scattering by whistler waves. We find that the wave power is positively correlated with both the Alfvén Mach number in the normal incidence frame MA and in the de Hoffmann–Teller frame MA/cos θBn. The empirical relation with MA/cos θBn is compared with the theory of SSDA that predicts a threshold wave power proportional to (MA/cos θBn)−2. The result suggests that the wave power exceeds the theoretical threshold for MA/cos θBn≳30–60, beyond which efficient electron acceleration is expected. This aligns very well with previous statistical analysis of electron acceleration at Earth's bow shock [Oka et al., Geophys. Res. Lett. 33, 5–6 (2006)]. Therefore, we consider that this study provides further support for SSDA as the mechanism of electron acceleration at Earth's bow shock. At higher-Mach-number astrophysical shocks, SSDA will be able to inject electrons into the diffusive shock acceleration process for subsequent acceleration to cosmic-ray energies.
Effects of the turbulent incoming flow condition on the wind–snow flow characteristics and accretion distribution in the cutting area of the high-speed railway
Authors: Wang Jiabin , Liu Haoyuan , Chen Guang , Li Xiaobai , Liu Cao , Gao Guangjun
Published: April 2024

In addressing snowdrift disasters in high-speed railway cutting areas, this study utilized the improved delayed detached eddy simulation turbulence model, synthetic eddy method, and Eulerian two-phase flow model (Euler–Euler). Coupled with grid dynamic deformation techniques, the investigation facilitated extracting temporal variations in snow particle accumulation profiles within the cutting areas. The predicting accuracy of the numerical method was validated through the wind tunnel and wind–snow experimental data. Building upon this foundation, the study investigated how uniform and turbulent flow conditions impact snow distribution in the high-speed railway cutting areas. The analysis examined the turbulent flow structures, friction velocity distribution, and snow accretion contours within the cutting area. Findings indicate that the snow mass on the windward slope in the cutting area remains consistent under both flow conditions. However, there are significant differences in the rate of snow mass growth and the characteristics of snow accretion distribution. The disappearance of vortex structures at the base of the leeward slope is crucial for indicating the transition in the accumulation states of the surrounding snow particles. Under turbulent incoming flow conditions, the transition from large-scale vortex systems to vortex pairs on the leeward slope of the cutting is delayed, resulting in a postponed stable growth period for snow accretion. Additionally, strong erosion between the track bed and the leeward slope results in reduced snow accretion mass in these areas. In particular, at the simulation time of t = 150 min, under turbulent incoming flow conditions, the overall snow accumulation in the cutting decreased by 20.8% compared to the uniform incoming flow conditions. The snow mass in the leeward slope area decreased by 38.3%, and the track bed area experienced a 23.3% reduction in snow accumulation. In contrast, the snow quantity on the windward slope remained relatively consistent.
Impact of annealing on the resistance of Li3PO4 electrolyte–LiNi0.5Mn1.5O4 electrode interfaces
Authors: Kawasoko Hideyuki , Shiraki Susumu , Nishio Kazunori , Oi Asuka , Shimizu Ryota , Hitosugi Taro
Published: April 2024

The operation of solid-state Li batteries, which are promising power supplies for portable electronic devices and electric vehicles, is accompanied by heating. Therefore, investigating the thermal stability of battery systems is essential. In this study, we report the impact of annealing on the interface of a Li3PO4 electrolyte and LiNi0.5Mn1.5O4 electrode in thin-film batteries. The batteries with the interface annealed at 200 °C show low Li3PO4–LiNi0.5Mn1.5O4 interface resistance of 7.2 Ω cm2. Furthermore, the batteries exhibit stable charge–discharge characteristics with high current density up to 1170 μA cm−2, similar to those of batteries with the non-annealing interface. The batteries with the interface annealed at 450 °C show high Li3PO4–LiNi0.5Mn1.5O4 interface resistance of 490 Ω cm2, resulting in low battery performance. X-ray photoemission spectroscopy indicates that the P in Li3PO4 is reduced by high-temperature annealing, possibly causing the performance degradation of batteries. This study provides an in-depth understanding of the interfaces of solid-state batteries and is expected to facilitate the development of thermally stable batteries.
Analytical reconstruction of axisymmetric curved shock wave/boundary layer interactions
Authors: Cheng Jianrui , Zhang Tao , Shi Chongguang , Da Xingya , Zhu Chengxiang , You Yancheng
Published: April 2024

In practical aerodynamic scenarios, interactions between curved shock waves and boundary layers with composite shock curvatures in both streamwise and spanwise directions are encountered more frequently than those induced by planar oblique shocks. To gain a more systematic understanding of this phenomenon in physics, internal and external axisymmetric curved shock wave/boundary layer interactions (AC-SBLI) are being studied analytically by establishing the underlying relations within the flow structures. Specifically, based on reconstructing the dominant structures of AC-SBLI as a semi-analytical model, this study focuses on the impacts of shock spanwise curvatures on separation and the mechanism of their action. It reveals that spanwise curvatures affect the separation in both internal and external AC-SBLI, but each exhibits a different influence pattern, emphasizing apparent axisymmetric characteristic. The spanwise curvatures exert influence indirectly by altering the compression ratio and directly by affecting the distribution of streamwise shock intensities. These findings propose a new approach to estimating the flow structures in AC-SBLI, where analyzing the spanwise curvatures will assist with comprehending other more intricate three-dimensional separation phenomena.
Mechanism of periodic oscillation in low-Reynolds-number buffet around an airfoil at angle of attack 0
Authors: Fujino Ken , Suzuki Kojiro
Published: April 2024

In this study, the low-frequency oscillations found in the compressible low-Reynolds-number regime, defined as low-Reynolds-number buffet, were investigated by numerical calculations and modal analysis. Dynamic mode decomposition (DMD) and compressive sensing methods were employed to extract periodic flow structures. Numerical simulation results showed low-Reynolds-number buffet and Kármán vortex shedding. Low- and high-frequency oscillations [St=O(0.01), O(1.0)] were extracted by DMD and named the buffet mode and vortex shedding mode, respectively. Low-Reynolds-number buffet does not necessarily exhibit supersonic regions or shock wave. Simulation results show that the thickness of the separated shear layer changes significantly under low-Reynolds-number buffet. The change in the thickness of the separated shear layer was confirmed by the buffet mode of DMD results. Two types of compression pressure waves, advecting upstream, were identified. DMD indicated that they resulted from vortex shedding. According to simulation and DMD results, the origin of the shock waves appears to be the condensation of compression pressure waves due to the vortex shedding mode and expansion in the supersonic region due to the buffet mode. The formation of the shock waves seems to be subordinated to the vortex shedding mode and the buffet mode. A feedback model for low-Reynolds-number buffet inherent in separated shear layers, which does not require supersonic regions or shock waves, was proposed. Supersonic regions highly condensed the compression pressure waves, inducing a larger separation region and amplifying the oscillation. The role of supersonic regions in determining oscillation amplitudes was evidenced, although supersonic regions are not essential to the mechanism of low-Reynolds-number buffet.
Comparative thermo-fluidic analysis of condensation characteristics inside smooth and enhanced tubes
Authors: Kumar Anil , Kumar Ravi , Das Arup Kumar
Published: April 2024

Three-dimensional simulations are performed to investigate the thermo-fluidic characteristics during the flow condensation of representative R134a refrigerant inside smooth and enhanced tubes. Along with a perfectly smooth surface, four different surface structures, i.e., hemispherical ribs, conical fins, axial, and circumferential continuous protrusions (tunnels and huddles) on the inner surface of the tube are tried to understand the heat transfer enhancement mechanism. Simulations are carried out for the mass flux ranging from 100 to 200 kg m−2 s−1 and inlet vapor quality of 0.8 at a phase change temperature of 40 °C. The effect of structures on the flow behavior is analyzed, and the presence of directional condensate drainage near the protrusions is observed. The qualitative and quantitative examinations of interfacial structures at different axial and longitudinal sections are also presented to better understand the distinctive condensation phenomenon for smooth and enhanced tubes. The spatial and time-averaged vapor fraction and liquid film thickness show lower values in the case of enhanced tubes compared to the smooth surface for all tested operating conditions. Furthermore, the hemispherical rib structure showed the highest heat transfer coefficient among the tested structures, whereas a tube with circumferential protrusions (huddles) results in maximum pressure drop during flow condensation. The benefits of heat transfer enhancement appear to be more than the pressure drop penalty for tubes with a conical fin structure and axial tunnels.
Exploring orientation-dependent interface engineering in manganite heterostructures
Authors: Xu Chengcheng , Dai Song , Qin Zheng , Liu Xingyue , Huang Jingwen , Xu Zhipeng , Wang Junjie , Yin Chengye , Xu Liqiang , Han Kun , Wu Wenbin , Chen Pingfan , Huang Zhen
Published: April 2024

The crucial role of interface engineering in controlling functionality has been well documented in the (001)-orientated perovskite oxide heterostructures; however, limited attention has been given to other epitaxial orientations. In this study, the (La,Sr)MnO3 heterostructure is selected to present the epitaxial-orientation-dependent interface engineering strategies based on magnetoelectric coupling and oxygen octahedral coupling. When capped by a ferroelectric PbTiO3 layer for interlayer magnetoelectric coupling, the (001) (La,Sr)MnO3 layer exhibits the most significant magnetic modulations compared to (110) and (111) counterparts. This can be attributed to the PbTiO3's out-of-plane polarization that depends on the epitaxial orientations. Also, if considering the interfacial oxygen octahedral structure in terms of epitaxial orientations, the buffer (or cap) layer hosts the most part of interfacial oxygen octahedra and, thus, plays a dominant role in controlling oxygen octahedral coupling of (001)-orientated [or (110)-orientated] perovskite heterostructures. This is consistent with our observations that for the (001) [or (110)] (La,Sr)MnO3 heterostructures, the DyScO3 buffer layer offers the more (or less) effective magnetic modulations compared to the cap one. These findings underscore the orientation-dependent nature of interface engineering in manganite heterostructures as well as in other perovskite heterostructures for tailoring functionalities.
Simulation-based insights into cell encapsulation dynamics in droplet microfluidics
Authors: Jannati Kamal , Rahimian Mohammad-Hassan , Raisee Mehrdad , Jafari Azadeh
Published: April 2024

In the context of microfluidic technology, investigating the encapsulation of single cells is of great importance, providing valuable insight into cellular behavior and contributing to advancements in single-cell analysis. This paper presents a computational investigation into the dynamics of single-cell encapsulation within a flow-focusing microfluidic system, with a specific emphasis on addressing the challenges associated with high-efficiency encapsulation. This study utilizes a combined lattice Boltzmann and immersed boundary method to provide an accurate simulation of a three-phase system. This allowed for an in-depth exploration of various critical parameters, including cell injection frequency, cell size, and inlet position. This study identifies optimal conditions for maximizing single-cell encapsulation efficiency, emphasizing the impact of the ratio between cell injection and droplet generation frequencies on encapsulation outcomes. This study investigates the effects of cell-induced changes on droplet formation characteristics. It explains the generation of larger droplets and the occurrence of additional satellite droplets. These findings provide insight into the microfluidic platforms designed for single-cell assays, which have potential applications in various fields such as drug development and personalized therapies.
Optimal parallelization strategies for active flow control in deep reinforcement learning-based computational fluid dynamics
Authors: Jia Wang , Xu Hang
Published: April 2024

Deep reinforcement learning (DRL) has emerged as a promising approach for handling highly dynamic and nonlinear active flow control (AFC) problems. However, the computational cost associated with training DRL models presents a significant performance bottleneck. To address this challenge and enable efficient scaling on high-performance computing architectures, this study focuses on optimizing DRL-based algorithms in parallel settings. We validate an existing state-of-the-art DRL framework used for AFC problems and discuss its efficiency bottlenecks. Subsequently, by deconstructing the overall framework and conducting extensive scalability benchmarks for individual components, we investigate various hybrid parallelization configurations and propose efficient parallelization strategies. Moreover, we refine input/output (I/O) operations in multi-environment DRL training to tackle critical overhead associated with data movement. Finally, we demonstrate the optimized framework for a typical AFC problem where near-linear scaling can be obtained for the overall framework. We achieve a significant boost in parallel efficiency from around 49% to approximately 78%, and the training process is accelerated by approximately 47 times using 60 central processing unit (CPU) cores. These findings are expected to provide valuable insight for further advancements in DRL-based AFC studies.
Antiferroelectricity of titanite-type oxide SrTiGeO5 and its potential for power electronics applications
Authors: Uohashi Toshiya , Kuwano Taro , Hagiwara Manabu , Natori Kenji , Deguchi Kazuhiko , Taniguchi Hiroki
Published: April 2024

Antiferroelectric materials have recently received renewed attention due to the increased demand for energy-storage ceramics and power electronics applications. This study demonstrates antiferroelectricity in a titanite-type oxide, SrTiGeO5, through direct observation of a double D-E hysteresis loop by polarization measurements. Temperature dependence of dielectric permittivity shows a cusp around 550 K, indicating a relatively high antiferroelectric phase transition temperature for SrTiGeO5. It is suggested that an electric-field-induced rise of permittivity in SrTiGeO5 has the potential for application in protective circuits of power electronics devices. The present study paves the way for the development of innovative antiferroelectric applications.
Characteristics of evolution and collapse in spark-induced cavitation bubbles
Authors: Qu Tong , Zhou Maolin , Luo Jing , Xu Weilin , Bai Lixin , Zhai Yanwei , Li Jie
Published: April 2024

Numerous scientists have thoroughly researched cavitation bubble dynamics using experimental methods such as tube arrest, underwater discharge, ultrasound, and laser focusing. In this study, with the aid of high-speed photography, the formation mechanism of the electrode-contact spark-induced cavitation bubble is discovered, i.e., electrolysis results in non-condensable gases wrapping the small inter-electrode gaps, and the non-condensable gases are broken down by discharge to form plasma, which then induces the cavitation bubble. Since the cavitation bubbles already contain a certain amount of non-condensable gases during the discharge process, the differences in the spatiotemporal evolution and collapse characteristics of the cavitation bubbles with varying amounts of non-condensable gases are further analyzed. The results show that underwater electrode-contact discharge system has an optimal voltage if the capacitance and discharge electrode size remain constant, and the cavitation bubbles generated under the optimal voltage condition are not only morphologically closest to the laser-induced cavitation bubbles, but also the change in radius over time during collapse is quite consistent with the Rayleigh bubble. Furthermore, compared to cavitation bubbles generated under varying voltages, those induced by the optimal voltage have a lower amount of non-condensable gases. This leads to the minimum first contraction radius and the maximum rebound radius being close to the corresponding values of the laser-induced cavitation bubbles. These new findings are of great significance for the improvement of experimental technology in the study of cavitation bubble dynamics, obtaining precise and dependable experimental data, and validating numerical simulations.
Study and optimization of a deformable trimaran amphibious transport vehicle's resistance characteristic
Authors: Liu Bolong , Pan Dibo , Xu Xiaojun
Published: April 2024

Amphibious transport vehicles have increasingly become an important tool for connecting water and land transportation, serving both water and land transport missions. However, due to the unique shape of amphibious vehicles, their sailing resistance is high, which severely restricts their widespread use. In this paper, a deformable trimaran amphibious transport vehicle with retractable side hulls is designed. Based on the Reynolds-averaged Navier–Stokes equation, a resistance prediction method for amphibious vehicles is established and verified through towing experiments. The resistance characteristic of the trimaran vehicle is studied and optimized. First, the effects of the side hull and its position on resistance performance are analyzed, and the sensitivity of position parameters is evaluated. Then, the bow plate angle on resistance is analyzed. Finally, a surrogate model of the side hull position parameters and the bow plate angle with resistance is established using the Kriging method. The Particle Swarm Optimization is used to search for the minimum resistance configuration Opt 2, which achieves a drag reduction effect of 19.84% at the design speed.
Effect of the vertical magnetic field on the bubble dynamic behaviors during photoelectrochemical water splitting
Authors: Feng Yuyang , Wang Yechun , Zhang Bo , Cao Zhenshan , Liu Miaomiao , Zhen Canghao , Guo Liejin
Published: April 2024

The bubble dynamic behaviors on the electrode surface are significantly affected by the magnetohydrodynamic (MHD) flow induced by the Lorentz force resulting from the applied magnetic field. However, the mechanism of the impact of a magnetic field perpendicular to the electrode on the dynamic behaviors of bubble remain unclear. In this study, the evolution law of a single oxygen bubble on the surface of a TiO2 photoelectrode under the influence of a vertical magnetic field with different magnetic induction intensities was investigated. The presence of a vertical magnetic field effectively promoted the rapid detachment of bubbles from the electrode surface and greatly improved the gas evolution efficiency. The mass transfer was dominated by single-phase free convection during bubble evolution. Under the influence of the vertical magnetic field, the mass transfer coefficient near the electrode was enhanced, and the adverse effects of bubbles on mass transfer were counteracted when they entered the reaction-controlled growth phase. The further multiphysics simulation found that the MHD convection decreased the local supersaturation of reaction product oxygen molecules near the electrode, thereby reducing concentration overpotential and increasing the reaction rate. This study provides an experimental and theoretical basis for promoting the bubble detachment and the reaction rate on the gas evolving electrode surface during photoelectrochemical water splitting.
Experimental study on permeability evolution of sandstone under cyclic loading
Authors: Wang Meng , Zhang Chunyu , Liu Rentai , Bai Jiwen , Chen Bing , Sui Jiancai , Sun Xiang
Published: April 2024

The permeability of a rock mass affects the site selection and construction of underground high-pressure gas storage for compressed-air energy storage. This study investigates the permeability evolution of sandstone under high-pressure gas during the cycle of confining and axial pressures. Nitrogen permeation tests were conducted at different inlet pressures using the steady-state method. The initial steady-state flow, seepage in the circulation, and steady-state flow after circulation were measured continuously in three stages. The effects of the loading and unloading rates and load-holding time on the seepage flow were analyzed. The results indicate that the flow rate and displacement changed with periodic changes in the axial and confining pressures during the cycle. The higher the inlet pressure, the greater was the difference between the peak and trough of the flow in the cycle, and the greater was the difference between the flow after the cycle and the initial flow. When the inlet pressure was 10 MPa, the steady-state flow rate increased from 284 ml/min to 336 ml/min (18%). When the inlet pressure was 2 MPa, the evolution range of the seepage flow in the sample was similar for different load-holding times. The loading and unloading rates had a significant influence on the flow waveform in the circulation process but little influence on the wave height. With an increase in the number of cycles, the porosity of the samples first decreased rapidly and then increased slowly. This study provides a reference for construction and operation of compressed-air energy-storage systems.
Influence of wind directionality on the three-dimensional distortion of buffeting force on a streamlined bridge deck: Insight into the pylon interference effect
Authors: Li Zhiyang , Li Shaopeng , Yang Qingshan , Hui Yi , Wang Yuhang , Zhang Cong
Published: April 2024

The present work aims to experimentally investigate the influence of wind directionality on the three-dimensionality of buffeting force on a streamlined bridge deck, considering the pylon interference effect (PIE). The pylon has an obvious impact on the downstream flow structure under the skew wind, influencing the aerodynamic loads acting on the bridge deck. The results show that the most dangerous wind direction exists at 30° for the downstream bridge deck, indicating the invalidation of the traditional “cosine rule.” It indicates that the lift force will be amplified due to the PIE, depending on the yaw angle of the oncoming flow. When turbulence passes through the pylon, the large-scale eddies in the wake region will be broken into small-scale eddies, attenuating the integral length scale in comparison with that of the free-stream turbulence. Consequently, the lift spectrum and corresponding three-dimensional aerodynamic admittance (AAF) increase in the high-frequency domain, resulting in the decrease in the spanwise correlation under the skew wind. Notably, the two-dimensional (2D) AAF indicates that the 2D distortion effect of turbulence on the lift increases in the wake region, causing the 2D AAF to decay rapidly in the high-frequency domain.
Memory-compatible perpendicular magnetic tunnel junctions under bi-directional strobe write pulses: A method for generating true random number bits at high speed
Authors: Sun Jonathan Z.
Published: April 2024

We propose an operation method of generating true random number bits with a perpendicular magnetic tunnel junction (pMTJ) already in use as a memory element in spin-transfer-torque driven magnetic random access memory technology. This method uses a set of regularly spaced (or intentionally irregularly spaced), minimum width, and bi-directional fast strobe-write pulses, with read operations after each write. The resulting bit-stream’s statistical properties are analyzed, and a few digital logic operation following the read is described that could significantly improve the resulting bit-streams variance and stability, insulating those from the raw variations of pMTJs.
Bubble ring entrapment during a water drop impact on viscous oil films
Authors: Luo Lang , Tian Yuan Si , Li Er Qiang
Published: April 2024

Air entrapment during the drop impact on a liquid surface is crucial to the ocean–atmosphere mass transfer process. Herein, we report a new mechanism of air entrapment. When a water drop impacts a highly viscous oil film, a bubble ring with a volume of approximately 2% of that of the initial drop is entrapped and disintegrated into multiple bubbles underneath the spreading lamella, which eventually float and burst to emit singular jets near the free surface. The reconstructed profile of the deformed oil film by the laser-induced fluorescence technique reveals the formation of the ridge and valley, which leads to the bubble ring entrapment between the two layers. The effect of the impact velocity on the annular ridge structure and bubble volume is discussed. The onset of the bubble ring disintegration is theoretically predicted, which agrees well with experimental data. Finally, the parameter space of bubble ring entrapment is presented in the regime maps, where three parameters including the impact Weber number, the dimensionless oil viscosity, and film thickness are considered.
Improved midgap recombination lifetimes in GaN crystals grown by the low-pressure acidic ammonothermal method
Authors: Shima K. , Kurimoto K. , Bao Q. , Mikawa Y. , Saito M. , Tomida D. , Uedono A. , Ishibashi S. , Ishiguro T. , Chichibu S. F.
Published: April 2024

To investigate the carrier recombination processes in GaN crystals grown by the low-pressure acidic ammonothermal (LPAAT) method, the photoluminescence (PL) spectra and PL lifetimes of LPAAT GaN crystals grown on acidic ammonothermal (AAT) GaN seed crystals were correlated with the growth polarity and species/concentration of point defects. The PL spectra of LPAAT GaN grown toward the (0001¯) direction (−c region), which provided the highest growth rate, exhibited a predominant near-band edge (NBE) emission. Neither bandgap narrowing nor Burstein–Moss shifts due to high concentration residual impurities were observed in the NBE emissions, indicating higher purity than the previously reported AAT GaN crystals. In addition, strain-induced energy shift or energy broadening of excitonic emission peaks was not observed, indicating excellent crystal coherency. Because of the reduced concentration of midgap recombination centers, a record-long room-temperature PL lifetime for the NBE emission of ammonothermal GaN (40 ps) was obtained from the −c region. Meanwhile, the PL spectra also exhibited the yellow and blue luminescence bands originating from particular deep-state radiative recombination centers. The major vacancy-type defects acting as midgap recombination centers are identified as vacancy complexes comprising a Ga vacancy (VGa) and a few N vacancies (VN), namely, VGa(VN)n buried by H and/or O, where n is an integer. Further reduction of such defect complexes will allow less compensated stable carrier concentration in the LPAAT GaN crystals.
An acceleration model for low-speed flames in curved channels
Authors: Li Tao , Ye Yue , Wang Xiaohan , Xu Baopeng
Published: April 2024

This study investigates the initial acceleration process of low-speed flames in curved channels. It also examines how the curvature and width of the channels influence flame propagation patterns and mechanisms. Previous research has highlighted the advantages of curved channels in facilitating flame acceleration. Subsequent studies have explored the interaction between pressure waves and flames, particularly in the later stages of flame propagation, leading to a high-speed flame phase. However, the effects of curvature and channel width on the initial acceleration phase of low-speed flames remain unclear. To address this gap, the present study utilizes theoretical methods to analyze the early acceleration phase of flames in curved channels with fixed curvature and width, from the closed end to the open end. Semi-analytical theoretical solutions are derived to determine the shape of the unburned gas flow field, flame front, and flame acceleration rate. The results demonstrate that the flow field shape deviates from axial symmetry to conserve angular momentum, favoring the inner wall of the curved channel and causing the flame front to adhere to it. In channels with small curvature, increasing the width leads to a decrease in the flame acceleration rate. Conversely, in channels with large curvature, widening the channel results in an increased flame acceleration rate. These findings provide theoretical insights for optimizing the design of the front-stage structure of curved detonation channels.
Neuronal innervation regulates the secretion of neurotrophic myokines and exosomes from skeletal muscle
Authors: Huang Kai-Yu , Upadhyay Gaurav , Ahn Yujin , Sakakura Masayoshoi , Pagan-Diaz Gelson J. , Cho Younghak , Weiss Amanda C. , Huang Chen , Mitchell Jennifer W. , Li Jiahui , Tan Yanqi , Deng Yu-Heng , Ellis-Mohr Austin , Dou Zhi , Zhang Xiaotain , Kang Sehong , Chen Qian , Sweedler Jonathan V. , Im Sung Gap , Bashir Rashid , Chung Hee Jung , Popescu Gabriel , Gillette Martha U. , Gazzola Mattia , Kong Hyunjoon
Published: April 2024

Myokines and exosomes, originating from skeletal muscle, are shown to play a significant role in maintaining brain homeostasis. While exercise has been reported to promote muscle secretion, little is known about the effects of neuronal innervation and activity on the yield and molecular composition of biologically active molecules from muscle. As neuromuscular diseases and disabilities associated with denervation impact muscle metabolism, we hypothesize that neuronal innervation and firing may play a pivotal role in regulating secretion activities of skeletal muscles. We examined this hypothesis using an engineered neuromuscular tissue model consisting of skeletal muscles innervated by motor neurons. The innervated muscles displayed elevated expression of mRNAs encoding neurotrophic myokines, such as interleukin-6, brain-derived neurotrophic factor, and FDNC5, as well as the mRNA of peroxisome-proliferator-activated receptor γ coactivator 1α, a key regulator of muscle metabolism. Upon glutamate stimulation, the innervated muscles secreted higher levels of irisin and exosomes containing more diverse neurotrophic microRNAs than neuron-free muscles. Consequently, biological factors secreted by innervated muscles enhanced branching, axonal transport, and, ultimately, spontaneous network activities of primary hippocampal neurons in vitro. Overall, these results reveal the importance of neuronal innervation in modulating muscle-derived factors that promote neuronal function and suggest that the engineered neuromuscular tissue model holds significant promise as a platform for producing neurotrophic molecules.
Genetic and phenotypic profiling of single living circulating tumor cells from patients with microfluidics
Authors: Dong Zaizai , Wang Yusen , Xu Gaolian , Liu Bing , Wang Yang , Reboud Julien , Jajesniak Pawel , Yan Shi , Ma Pingchuan , Liu Feng , Zhou Yuhao , Jin Zhiyuan , Yang Kuan , Huang Zhaocun , Zhuo Minglei , Jia Bo , Fang Jian , Zhang Panpan , Wu Nan , Yang Mingzhu , Cooper Jonathan M. , Chang Lingqian
Published: April 2024

Accurate prediction of the efficacy of immunotherapy for cancer patients through the characterization of both genetic and phenotypic heterogeneity in individual patient cells holds great promise in informing targeted treatments, and ultimately in improving care pathways and clinical outcomes. Here, we describe the nanoplatform for interrogating living cell host-gene and (micro-)environment (NICHE) relationships, that integrates micro- and nanofluidics to enable highly efficient capture of circulating tumor cells (CTCs) from blood samples. The platform uses a unique nanopore-enhanced electrodelivery system that efficiently and rapidly integrates stable multichannel fluorescence probes into living CTCs for in situ quantification of target gene expression, while on-chip coculturing of CTCs with immune cells allows for the real-time correlative quantification of their phenotypic heterogeneities in response to immune checkpoint inhibitors (ICI). The NICHE microfluidic device provides a unique ability to perform both gene expression and phenotypic analysis on the same single cells in situ, allowing us to generate a predictive index for screening patients who could benefit from ICI. This index, which simultaneously integrates the heterogeneity of single cellular responses for both gene expression and phenotype, was validated by clinically tracing 80 non–small cell lung cancer patients, demonstrating significantly higher AUC (area under the curve) (0.906) than current clinical reference for immunotherapy prediction.
Incomplete-penetrant hypertrophic cardiomyopathy
MYH7
G256E mutation causes hypercontractility and elevated mitochondrial respiration
Authors: Lee Soah , Vander Roest Alison S. , Blair Cheavar A. , Kao Kerry , Bremner Samantha B. , Childers Matthew C. , Pathak Divya , Heinrich Paul , Lee Daniel , Chirikian Orlando , Mohran Saffie E. , Roberts Brock , Smith Jacqueline E. , Jahng James W. , Paik David T. , Wu Joseph C. , Gunawardane Ruwanthi N. , Ruppel Kathleen M. , Mack David L. , Pruitt Beth L. , Regnier Michael , Wu Sean M. , Spudich James A. , Bernstein Daniel
Published: April 2024

Determining the pathogenicity of hypertrophic cardiomyopathy–associated mutations in the β-myosin heavy chain (
MYH7
) can be challenging due to its variable penetrance and clinical severity. This study investigates the early pathogenic effects of the incomplete-penetrant
MYH7
G256E mutation on myosin function that may trigger pathogenic adaptations and hypertrophy. We hypothesized that the G256E mutation would alter myosin biomechanical function, leading to changes in cellular functions. We developed a collaborative pipeline to characterize myosin function across protein, myofibril, cell, and tissue levels to determine the multiscale effects on structure–function of the contractile apparatus and its implications for gene regulation and metabolic state. The G256E mutation disrupts the transducer region of the S1 head and reduces the fraction of myosin in the folded-back state by 33%, resulting in more myosin heads available for contraction. Myofibrils from gene-edited
MYH7
WT/G256E
human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) exhibited greater and faster tension development. This hypercontractile phenotype persisted in single-cell hiPSC-CMs and engineered heart tissues. We demonstrated consistent hypercontractile myosin function as a primary consequence of the
MYH7
G256E mutation across scales, highlighting the pathogenicity of this gene variant. Single-cell transcriptomic and metabolic profiling demonstrated upregulated mitochondrial genes and increased mitochondrial respiration, indicating early bioenergetic alterations. This work highlights the benefit of our multiscale platform to systematically evaluate the pathogenicity of gene variants at the protein and contractile organelle level and their early consequences on cellular and tissue function. We believe this platform can help elucidate the genotype–phenotype relationships underlying other genetic cardiovascular diseases.
The tRNA
Val
half: A strong endogenous Toll-like receptor 7 ligand with a 5′-terminal universal sequence signature
Authors: Pawar Kamlesh , Kawamura Takuya , Kirino Yohei
Published: April 2024

Toll-like receptors (TLRs) are crucial components of the innate immune system. Endosomal TLR7 recognizes single-stranded RNAs, yet its endogenous ssRNA ligands are not fully understood. We previously showed that extracellular (ex-) 5′-half molecules of tRNA
HisGUG
(the 5′-tRNA
HisGUG
half) in extracellular vesicles (EVs) of human macrophages activate TLR7 when delivered into endosomes of recipient macrophages. Here, we fully explored immunostimulatory ex-5′-tRNA half molecules and identified the 5′-tRNA
ValCAC/AAC
half, the most abundant tRNA-derived RNA in macrophage EVs, as another 5′-tRNA half molecule with strong TLR7 activation capacity. Levels of the ex-5′-tRNA
ValCAC/AAC
half were highly up-regulated in macrophage EVs upon exposure to lipopolysaccharide and in the plasma of patients infected with
Mycobacterium tuberculosis
. The 5′-tRNA
ValCAC/AAC
half-mediated activation of TLR7 effectively eradicated bacteria infected in macrophages. Mutation analyses of the 5′-tRNA
ValCAC/AAC
half identified the terminal GUUU sequence as a determinant for TLR7 activation. We confirmed that GUUU is the optimal ratio of guanosine and uridine for TLR7 activation; microRNAs or other RNAs with the terminal GUUU motif can indeed stimulate TLR7, establishing the motif as a universal signature for TLR7 activation. These results advance our understanding of endogenous ssRNA ligands of TLR7 and offer insights into diverse TLR7-involved pathologies and their therapeutic strategies.
Culturas juveniles como catalizador de la pragmaticalización de los marcadores tipo y
onda en Argentina y México
Authors: Mihatsch Wiltrud , Vazeilles Ana
Published: April 2024

Abstracta

En distintas variedades latinoamericanas del español existe una serie de marcadores pragmáticos propios de la
oralidad coloquial que cumplen funciones similares. Los marcadores tipo y onda son atenuadores,
pero también tienen un valor de aproximación, ejemplificación, focalización, estructuración discursiva y pueden funcionar como
marcadores de cita. Las funciones pragmáticas se pueden datar a partir de la segunda mitad del siglo XX, se establecen en los años
ochenta y noventa, y en la actualidad siguen, en su mayor parte, asociadas al lenguaje juvenil. Al mismo tiempo, datos aislados
sugieren el contexto de las contraculturas de los años sesenta y setenta como probable catalizador que lleva a la
pragmaticalización. Proponemos un estudio comparativo de los usos en la variedad argentina y la variedad mexicana mediante un
análisis de corpus y una encuesta en el marco de la “lingüística popular” que toma en cuenta las estimaciones metalingüísticas de
los hablantes acerca del origen de los marcadores.
Constant velocity physical warp drive solution
Authors: Fuchs Jared , Helmerich Christopher , Bobrick Alexey , Sellers Luke , Melcher Brandon , Martire Gianni
Published: April 2024

Warp drives are exotic solutions of general relativity that offer novel means of transportation. In this study, we present a solution for a constant-velocity subluminal warp drive that satisfies all of the energy conditions. The solution involves combining a stable matter shell with a shift vector distribution that closely matches well-known warp drive solutions such as the Alcubierre metric. We generate the spacetime metric numerically, evaluate the energy conditions, and confirm that the shift vector distribution cannot be reduced to a coordinate transformation. This study demonstrates that classic warp drive spacetimes can be made to satisfy the energy conditions by adding a regular matter shell with a positive ADM mass.
Thermal defocus-free Hartmann Wavefront Sensors for monitoring aberrations in Advanced Virgo
Authors: Aiello Lorenzo , Palma Pier Paolo , Lorenzini Matteo , Cesarini Elisabetta , Cifaldi Maria , Di Fronzo Chiara , Lumaca Diana , Minenkov Yury , Nardecchia Ilaria , Rocchi Alessio , Taranto Claudia , Fafone Viviana
Published: April 2024

Earth-based gravitational waves interferometric detectors are shot-noise limited in the high-frequency region of their sensitivity band. While enhancing the laser input power is the natural solution to improve on the shot noise limit, higher power also increases the optical aberration budget due to the laser absorption in the highly reflective coatings of mirrors, resulting in a drop of the sensitivity of the detector. Advanced Virgo exploits Hartmann Wavefront Sensors (HWSs) to locally measure the absorption-induced optical aberrations by monitoring the optical path length change in the core optics. Despite the very high sensitivity of Hartmann sensors, temperature fluctuations can cause a spurious curvature term to appear in the reconstructed wavefront due to the thermal expansion of the Hartmann plate, that could affect the accuracy of the aberration monitoring. We present the implementation and validation of a control loop to stabilize the Advanced Virgo HWS temperature at the order of

Δ
T
⩽
0.01

 K, keeping the spurious curvature within the detector’s requirements on wavefront sensing accuracy.
The internal ballistics of a spring gun
Authors: Ivchenko Vladimir
Published: April 2024

We consider the features of pellet motion under the elastic force acting from a decompressing spring of a finite mass. The muzzle speed of the pellet decreases as the ratio between spring and pellet mass increases. In the general case, the pellet loses contact with the spring as it is stretched. This effect occurs due to the fact that the peak of elastic displacement wave, propagating from the fixed end, reaches the opposite end of the spring. With a large relative mass of the pellet, it accelerates along a quarter of the sinusoid. At the limit of a very small pellet mass, it moves nearly all the time along with the end of the spring at an almost constant speed, approximately equal to the speed of sound propagation in the spring. In this case, after the initial compression, the pellet passes the equilibrium position, and comes off after moving a similar distance beyond the equilibrium.
Photonic quasi-crystal fiber electro-optical modulator
Authors: She Kang , Sheng Guo , Shan Zhengping , Xu Piaorong , Liu Exian
Published: April 2024

The integration of graphene with optical fiber is considered to be a new interdisciplinary research hotspot for functional fiber. In this paper, an electro-optical modulator based on a six-fold Stampfli-type photonic quasi-crystal fiber (PQF) is theoretically proposed with a sandwiched graphene/hexagonal boron nitride/graphene (Gr/hBN/Gr) film covering all the hole walls. This design exhibits a strong light-graphene interaction with an excellent modulation depth of ∼64 dB mm−1 at 1550 nm by applying an external bias voltage (below 30 V) on both graphene layers. As the Fermi level of the graphene changes with voltage, the fiber shows ‘On’ and ‘Off’ states, serving well as a light-switch. For the modulator performance, the dependence of modulation depth on multiple factors is studied in terms of the layer numbers of graphene and hBN films, the incident wavelength, and the structure parameters. Interestingly, an attenuation peak occurs due to the epsilon-near-zero effect in graphene and shows a linear relationship between the wavelength and the Fermi level. This design provides a guidance for the integration of PQF and graphene, and holds great promise for future all-fiber systems.