bluuebunny/crossref_metadata_2025 huggingface dataset:
Sediment and Water physicochemical characterization of Marchica Lagoon (Oriental Rif, Morocco)
Authors: Hrida Abdelghafour , Houssaini El Ghali Iraqi , Lamgharbaj Mustapha , Layachi Mostafa , Abdellaoui Benyounes , Taher Morad , Etebaai Issam
Published: March 2024

This study primarily focuses on the environmental assessment of the Marchica lagoon ecosystem. The objective of this research was to determine the ecological effects associated with the development, especially the opening of a new inlet, of the Marchica lagoon on the physicochemical parameters of its liquid phase, geochemical characteristics, as well as the distribution and content of sedimentary substrates. Two sampling campaigns were conducted in February 2023 and May 2023 within the Marchica lagoon to perform a detailed characterization of water physicochemical parameters, including temperature, pH, salinity, turbidity, dissolved oxygen, and chlorophyll. Additionally, a sedimentological and geochemical analysis of collected sediment samples was performed. The results highlight significant variations in these parameters, both in terms of location and temporal variations. Results of the sedimentological and geochemical study of the sediments are also included for a comprehensive understanding of the impact of management development on the lagoon's ecosystem.
Existence and uniqueness of the motion of a particle subject to a unilateral constraint and friction
Authors: Dance Christopher R.
Published: March 2024

We prove that there exists a unique solution to the initial value problem describing the motion of a particle subject to a unilateral constraint and Coulomb friction, if the external force acting on the particle is an analytic function of time and of the particle’s position and velocity. Previous work claimed that this problem has a local series solution that corresponds to an analytic function, after any impacts have been resolved. However, a counterexample to that claim was recently discovered, involving a particle starting to slide, in which the series solution is divergent, and thus does not correspond to an analytic function. This paper corrects previous arguments by considering a general formal series solution for a particle that is starting to slide.
Dual channel sales in supply chain: live streaming or traditional e-commerce
Authors: Zhou Xuejun , Liu Zhibing , Liu Jie , Pan Chen
Published: March 2024

In recent years, live streaming is becoming a popular channel to sell products all over the world. Compared to traditional e-commerce channel, live streaming channel may not only bring consumers more shopping convenience, but also pose consumers more privacy concern. This paper considers a supply chain consisting of a manufacturer and an e-tailer who sells through dual channels (i.e., live streaming and traditional e-commerce) to explore how shopping convenience and privacy concern affect the optimal decisions. We build game models of two pricing (exogenous and endogenous) and two incentive contracts (wholesale price and two-part tariff). We find that the optimal promotion efforts are decreasing in shopping convenience while increasing in privacy concerns under the wholesale price contract, and independent of them under the two-part tariff contract when pricing is not a decision (such as iPhone); the optimal promotion efforts are increasing in shopping convenience while decreasing in privacy concern when pricing is a decision (such as the seasonal products). Whether the retail pricing is a decision or not, supply chain coordination can be achieved by the two-part tariff contract, but not through the wholesale price contract. Further, the two-part tariff contract is more favorable to the manufacturer if the exogenously given retail price is low, and the wholesale price contract is more favorable to the manufacturer if the retail price is high; the two-part tariff contract is always more beneficial for the supply chain than the wholesale price contract. Finally, we extend our analysis to relax a more realistic form with a variable effort elasticity and verify the robustness of the theoretical results.
Design and construction of a refrigerator-cooled adiabatic calorimeter for heat capacity measurement in liquid helium temperature region
Authors: Luo Ji-Peng , Yin Nan , Lu Jia-Bao , Tan Zhi-Cheng , Shi Quan
Published: March 2024

Heat capacity is a fundamental thermodynamic property of a substance. Although heat capacity values and related thermodynamic functions are available for many materials, low-temperature heat capacity measurements, especially for novel materials, can still provide valuable insights for research in physics, chemistry, thermodynamics, and other fields. Reliable low-temperature heat capacity data are typically measured using classical adiabatic calorimeters, which use liquid helium as the refrigerant to provide a cryogenic environment for heat capacity measurements. However, liquid helium is not only expensive but also not easy to obtain, which greatly limits the application of adiabatic calorimetry. In this work, an accurate adiabatic calorimeter equipped with a Gifford–MacMahon refrigerator was designed and constructed for measuring the heat capacity of condensed matter in the temperature range from 4 to 100 K. The Gifford–MacMahon refrigerator was utilized to provide a stable liquid helium-free cryogenic environment. A simple mechanical thermal switch assembly was designed to facilitate switching between the refrigeration mode and the adiabatic measurement mode of the calorimeter. Based on the measurement results of standard reference materials, the optimized repeatability and accuracy of heat capacity measurements were determined to be within 0.8% and 1.5%, respectively. The heat capacity of α-Fe2O3 nanoparticles was also investigated with this device. Furthermore, this adiabatic calorimeter only requires electricity to operate in the liquid helium temperature range, which may significantly advance the research on low-temperature heat capacity based on adiabatic calorimetry.
Dual-polarized angle-selective surface based on double-layer frequency selective surface
Authors: Du Chao , Chen Huizhen , Wang Shaofei , Pang Yongqiang , Zhou Tao , Xia Song , Zhou Di
Published: March 2024

In this Letter, we propose a dual-polarized angle-selective surface (ASS) based on a double-layer frequency selective surface (FSS) to achieve angular selectivity. By appropriately constructing the structure of the single-layer FSS, bandpass and band-stop are produced by the ASS under normal and oblique incidences, respectively, resulting in exceptional angular selectivity. Simulated results show that the proposed low-pass ASS achieves a bandpass (|S21| > −1 dB) from 0° to 10° and a band-stop (|S21| < −20 dB) from 31° to 85° with a profile thickness of 0.6 λ. A low-pass ASS prototype with an operating frequency of 10 GHz is fabricated to demonstrate the design concept. The measured results of the transmission coefficients are in good agreement with the simulated results. The proposed ASS can play an important role in many applications, as in minimizing the side lobes of the antenna.
The temperature of maximum density for aqueous solutions
Authors: Troncoso Jacobo , González-Salgado Diego
Published: March 2024

Experimental and theoretical advances for understanding the temperature of maximum density (TMD) of aqueous solutions are outlined. The main equations that relate the TMD behavior to key thermodynamic properties are stated. The experimental TMD data are classified as a function of the nature of the solute (inorganic electrolytes, non-electrolytes, organic salts and ionic liquids, and amino acids and proteins). In addition, the experimental results that explore the effect of pressure are detailed. These experimental data are rationalized by making use of qualitative and semi-quantitative arguments based on the thermodynamics of aqueous systems. The main theoretical and simulation advances in TMD for aqueous solutions are also shown—including new calculations in the context of the scaled particle theory—and their ability to reproduce the experimental data is evaluated. Finally, new experiments and theoretical and simulation developments, which could give important insights into the problem of TMD for aqueous solutions, are proposed.
Tracking intrinsic ferroelectric switching under electric field via operando second harmonic generation
Authors: Dong Yangda , Tan Yangchun , Zhang Yuan , Dai Liyufen , Yuan Guangtong , Ren Chuanlai , Liu Zhenghao , Zhong Xiangli , Li Changjian , Wang Jinbin , Zhong Gaokuo , Li Jiangyu
Published: March 2024

Polarization hysteresis is the defining characteristic of ferroelectrics, though the measurement of ferroelectric hysteresis is often complicated by artifacts such as leakage current and not all materials with apparent electrical hysteresis are ferroelectric. In this Letter, we have set up an operando second harmonic generation (SHG) system to track intrinsic ferroelectric switches under electric field, which is free from leakage current interference, thus yielding a signature for intrinsic ferroelectricity. Taking representative PbZr0.2Ti0.8O3 (PZT) thin films with different thicknesses as examples, the operando SHG system can capture ferroelectric hysteresis not only for PZT films thicker than 50 nm, for which conventional hysteresis measurement works, but also for PZT film as thin as 26 nm, for which conventional measurement fails due to the presence of large leakage current. Different domain evolution processes in these films are also illustrated.
Control of a twisted domain wall motion supported by topology
Authors: Kim Seong Tae , Han Hee-Sung , Im Mi-Young , Je Soong-Geun
Published: March 2024

We report the topology-mediated modulation of a twisted domain wall speed in a thick perpendicularly magnetized system. By exploiting the topological robustness of the direction of the Bloch wall component in the twisted domain wall, we show that the domain wall speed either increases or decreases depending on whether the transverse magnetic field is parallel or antiparallel to the Bloch wall component. The decrease in the speed is maintained until the antiparallel transverse reaches ∼0.3 T, indicating that the twisted domain wall can offer wide controllability supported by the topological robustness which involves an injection of a Bloch point. We also demonstrate that the transverse magnetic field suppresses the Walker breakdown, allowing high mobility domain wall motion for a wide range of perpendicular driving fields.
Unraveling motion in proteins by combining NMR relaxometry and molecular dynamics simulations: A case study on ubiquitin
Authors: Champion Candide , Lehner Marc , Smith Albert A. , Ferrage Fabien , Bolik-Coulon Nicolas , Riniker Sereina
Published: March 2024

Nuclear magnetic resonance (NMR) relaxation experiments shine light onto the dynamics of molecular systems in the picosecond to millisecond timescales. As these methods cannot provide an atomically resolved view of the motion of atoms, functional groups, or domains giving rise to such signals, relaxation techniques have been combined with molecular dynamics (MD) simulations to obtain mechanistic descriptions and gain insights into the functional role of side chain or domain motion. In this work, we present a comparison of five computational methods that permit the joint analysis of MD simulations and NMR relaxation experiments. We discuss their relative strengths and areas of applicability and demonstrate how they may be utilized to interpret the dynamics in MD simulations with the small protein ubiquitin as a test system. We focus on the aliphatic side chains given the rigidity of the backbone of this protein. We find encouraging agreement between experiment, Markov state models built in the χ1/χ2 rotamer space of isoleucine residues, explicit rotamer jump models, and a decomposition of the motion using ROMANCE. These methods allow us to ascribe the dynamics to specific rotamer jumps. Simulations with eight different combinations of force field and water model highlight how the different metrics may be employed to pinpoint force field deficiencies. Furthermore, the presented comparison offers a perspective on the utility of NMR relaxation to serve as validation data for the prediction of kinetics by state-of-the-art biomolecular force fields.
Zero-field spin wave turns
Authors: Klíma Jan , Wojewoda Ondřej , Roučka Václav , Molnár Tomáš , Holobrádek Jakub , Urbánek Michal
Published: March 2024

Spin-wave computing, a potential successor to CMOS-based technologies, relies on the efficient manipulation of spin waves for information processing. While basic logic devices such as magnon transistors, gates, and adders have been experimentally demonstrated, the challenge for complex magnonic circuits lies in steering spin waves through sharp turns. In this study, we demonstrate with micromagnetic simulations and Brillouin light scattering microscopy experiments, that dipolar spin waves can propagate through 90° turns without distortion. The key lies in carefully designed in-plane magnetization landscapes, addressing challenges posed by anisotropic dispersion. The experimental realization of the required magnetization landscape is enabled by spatial manipulation of the uniaxial anisotropy using corrugated magnonic waveguides. The findings presented in this work should be considered in any magnonic circuit design dealing with anisotropic dispersion and spin wave turns.
Magnon–phonon coupling modulation via dimensional reduction in thin antiferromagnet MnPSe3 nanoribbons
Authors: Chen Wenkang , Zhao Ning , Huang Yuan , Zeng Xiaoliang , Zhang Kunhua , Zhou Jun , Xu Xiangfan
Published: March 2024

Two-dimensional (2D) magnetic materials have triggered tremendous interest in recent years due to their remarkable potential applications in magnetic storage and spintronics devices. Heat dissipation is of great significance in stability and durability of increasingly integrated magnetic devices. However, little investigation of thermal transport has been carried out in 2D magnetic materials and a comprehensive understanding of the underlying mechanism is still lacking. We experimentally demonstrate the thermal conductivity measurement of MnPSe3 nanoribbons and find a nonmonotonic thickness dependence, which is attributed to the phonon confinement effect in thin nanoribbons. The peaks of measured thermal conductivity are found to be modified with increasing thickness due to the magnon–phonon coupling. We propose that the magnon–phonon scattering rate increases with increasing thickness and causes a huge suppression in thermal conductivity. This study will deepen the understanding of the thermal properties of 2D magnetic materials and will benefit thermal management in designing magnetic devices.
A quantum algorithm for computing dispersal of submarine volcanic tephra
Authors: Basu Biswajit , Gurusamy Saravanan , Gaitan Frank
Published: March 2024

In this paper, we develop a quantum computing algorithm for solving the partial differential equation (PDE) for tephra dispersal through advection in the semi-infinite horizontal buoyant region of a submarine volcanic eruption. The concentration of pyroclastic particles in the fluid domain of a hydrothermal megaplume provides important information about the rate of volcanic energy release, mechanism of formation of the megaplume, and submarine depositional patterns. This work leveraging on previous works [F. Gaitan, NPJ Quantum Inf. 6, 61 (2020); F. Gaitan, Adv. Quantum Tech. 4, 2100055 (2021)] further opens up opportunities to solve wider classes of PDEs with different applications of interest. Some additional specific contributions of this work are transforming the semi-infinite spatial domain problem into a problem on a finite spatial domain for applying the quantum algorithm, and the investigation into the effect of spatial and temporal resolution on the solution of PDEs for the quantum algorithm. Furthermore, possible modification of the algorithm with different spatial discretization schemes has been presented and their influence and implications on the solution of the PDE have been discussed. Also, studies are conducted to examine the effect of regularity conditions in time and the presence of statistical noise in the spatial domain, on the solutions obtained using quantum algorithms. The study in this paper paves an important pathway to venture into other types of advection-diffusion problems.
Transient aerodynamic behavior of a high-speed Maglev train in plate braking under crosswind
Authors: Zhu Fentian , Xie Jiawang , Lv Dazhou , Xu Gang , Yao Huadong , Niu Jiqiang
Published: March 2024

The test speed of high-speed maglev trains (HSMT) exceeds 600 km/h, requiring higher braking performance and technology. Plate braking technology, which is a suitable choice, has been applied for engineering the high-speed test vehicles. However, the unsteady aerodynamic response during the opening process of HSMT under crosswind needs to be studied. This study explores the unsteady aerodynamic characteristics of a HSMT with a train speed of 600 km/h during plate braking at different crosswind speeds. The plate motion is achieved based on the dynamic grid technology, and the unsteady flow field around the train is simulated using the unsteady Reynolds time averaged equation and the shear stress transport k-omega (SST k–ω) turbulence model. This calculation method was verified using wind tunnel test data. The peak aerodynamic drag (AD) of the braking plates overshot during opening. Under a crosswind of 20 m/s, the AD peak of the first braking plate was 11% larger than that without crosswind. The middle braking plates were significantly affected by upstream vortex shedding, and the AD fluctuation was the most severe. The AD of the head and tail coaches is significantly affected by crosswind. With an increase in the crosswind speed, the AD of the head and tail coaches decreased and increased, respectively. Compared with no crosswind, under a crosswind of 20 m/s, the AD of the head coach decreased by 43%, and the AD of the tail coach increased by a factor of approximately 1.1 times. Furthermore, the AD fluctuation of the tail coach was the most severe.
Influence of Yb3+ percentage on emission of Er3+ doped into GdVO4 matrix
Authors: Ferreira Maria Fernanda , de Faria João Vitor Gonçalves , Pontes Lauany Mazzon , Crespi Marcela Guedes Matos , Rocha Lucas Alonso , Nassar Eduardo José
Published: March 2024

In this study, we used the non-hydrolytic sol–gel methodology to synthesize gadolinium vanadate particles doped with different Er3+ and Yb3+ molar ratios. Er3+ and Yb3+ chlorides and vanadium alkoxide were used as precursors during the sol–gel synthesis. The resulting powders were treated at 800 °C and characterized by x-ray diffraction and photoluminescence. The x-ray diffractogram displayed peaks attributed to the gadolinium vanadate matrix. Photoluminescence helped to evaluate the Fluorescence Intensity Ratio (FIR), which is important for understanding the nanothermometer property. The FIR of the GdVO4:Er3+/Yb3+ samples containing different Er3+ and Yb3+ molar ratios increased as a function of the laser power, which indicated that the local temperature increased. The excitation spectra obtained at fixed wavelengths of 525 and 555 nm displayed bands at 322, 379, and 489 nm, ascribed to the charge transfer band and Er3+ levels. Upon excitation at 321 nm, the emission spectra in the visible region presented intense bands at 525 and 555 nm, due to Er3+ emission, and excitation at 321 nm led to emission in the infrared region, 980 and 1550 nm. In conclusion, the synthesized system can be employed as a temperature sensor.
Numerical study of flow boiling heat transfer in a mini-channel under hyper-gravity
Authors: Lu Wei , Zhang Zhanru , Chen Yujie , Wang Bohong , Yu Bo , Sun Dongliang , Zhang Wei , Yang Yanru , Wang Xiaodong
Published: March 2024

Gravity plays a crucial role in influencing bubble behavior and heat transfer in flow boiling, and its impact can vary significantly in aerospace settings. Therefore, this study aims to numerically investigate flow boiling heat transfer in a rectangular mini-channel under hyper-gravity conditions, specifically at 12 times the normal gravity. To accomplish this, a coupled volume-of-fluid and level set method is employed, taking into account fluid-solid conjugated heat transfer as well as a nucleus site density model derived from experimental data. By reproducing the flow pattern and heat transfer characteristics under different heat flux and flow rate conditions, the study unveils the effects of hyper-gravity on flow boiling heat transfer. When the flow rate is lower under hyper-gravity conditions, a notable phenomenon occurs wherein numerous bubbles detach from the heating wall and coalesce into a vapor film at the top of the mini-channel due to increased buoyancy. In contrast, under normal gravity, bubbles merge and slide on the heating wall, leading to the formation of a dry patch below. Consequently, hyper-gravity results in a lower wall superheat, and the disparity in average wall superheat between normal and high gravities escalates as the added heat flux rises. Notably, in the hyper-gravity environment, the frequent detachment of bubbles in the middle and downstream sections of the mini-channel leads to an initial increase in wall superheating, followed by a plateau along the flow direction. As the flow rate increases, the inertial force intensifies. However, intriguingly, the discrepancy in flow boiling heat transfer between normal and high gravities does not exhibit a monotonic decrease with the increasing flow rate. This behavior can be attributed to the pressing of more bubbles onto the heating wall under normal gravity, resulting in the formation of dry patches at high velocities.
Insight into the interface effect and PTC effect on the temperature-adaptive electrical conductivity of epoxy composite
Authors: Teng Chenyuan , Li Shuo , Zhou Yuanxiang , Zhang Ling , Zhang Yunxiao , Huang Meng
Published: March 2024

Doping functional fillers into the polymeric matrix is an effective strategy to improve the electrical, thermal, and other performance of insulating materials. It is imperative to understand the influence of fillers on the charge carrier behavior to achieve better regulation effectiveness. In this work, micrometer-sized and nano-sized ceramic particles with positive temperature coefficient (PTC) electrical resistivity are employed to prepare the epoxy composites, whose electrical conductivity under different temperature and electric field, space charge characteristics, permittivity, and electric field distribution are studied. It is found that the doping of a PTC filler shifts the electrical conduction from bulk-controlled to electrode-limited, determining the quantity of charge carriers within epoxy composites. While the interface effect mainly affects the transport process of charge carriers, it would fail to dominate the electrical conduction since the abundant charge carrier introduced by the semiconductive functional filler. Combined with the reinforced interface effect, the electrical conductivity–temperature characteristic of the epoxy nanocomposite is optimized, leading to the reduction in the maximum electric field within electrical equipment insulation by 55%. These findings emphasize the synergistic regulation of charge carrier amount and transport, which contributes to the precision design of polymeric composites doped with functional fillers.
Effect of temperature on dislocation-tuned dielectricity and piezoelectricity in single-crystal BaTiO3
Authors: Dietrich Felix , Ni Fan , Fulanović Lovro , Zhou Xiandong , Isaia Daniel , Groszewicz Pedro B. , Zhang Chunlin , Xu Bai-Xiang , Rödel Jürgen , Buntkowsky Gerd , Zhuo Fangping
Published: March 2024

The pinning-controlled mobility of ferroelectric/ferroelastic domain walls is an important part of managing polarization switching and determining the final properties of ferroelectric and piezoelectric materials. Here, we assess the impact of temperature on dislocation-induced domain wall pinning as well as on dislocation-tuned dielectric and piezoelectric response in barium titanate single crystals. Our solid-state nuclear magnetic resonance spectroscopy results indicate that the entire sample exclusively permits in-plane domains, with their distribution remaining insensitive to temperature changes below the Curie temperature (TC). The domain wall pinning field monotonically decreases with increasing temperature up to TC, as evidenced by a combination of experimental observations and phase-field simulations. Our work highlights the promising potential of dislocation engineering in controlling domain wall mobility within bulk ferroelectrics.
Abrupt increase of stochastic behavior in domain-wall motion near depinning field
Authors: Kim Myeonghoe , Lee Seong-Hyub , Kim Minhwan , Kim Dong-Hyun , Choe Sug-Bong
Published: March 2024

The domain-wall motion in ferromagnetic films exhibits stochastic behavior due to thermal agitation with quenched disorders. The stochasticity is an obstacle in the sense of consistent repeatability of domain-wall position control in magnetic domain-wall devices. In general, the level of stochasticity is expected to decrease as driving force increases. This property suggests that the magnetic domain-wall devices are capable of simultaneously achieving both high operational speed and decrease in the level of stochasticity. However, we report here an observation of stochasticity anomaly, which involves a significant increase in relative speed dispersion near the depinning field. Domain-wall motion measurements were performed in ferromagnetic wires with perpendicular magnetic anisotropy over the same position to measure the relative speed dispersion. The stochasticity in domain-wall motion is intertwined with the number of pinning–depinning events throughout the domain-wall motion. The size of cluster events, which leads to the number of events, reflects the trend in the relative speed dispersion. The observed anomaly is provided by occurrence of large avalanches of cluster events. The anomaly occurs within the tech-relevant speed range of 1–100 m/s, signaling the necessity of material engineering to mitigate its effects.
Summation formulas generated by Hilbert space eigenproblem
Authors: Mali Petar , Gombar Sonja , Radošević Slobodan , Rutonjski Milica , Pantić Milan , Pavkov-Hrvojević Milica
Published: March 2024

We demonstrate that certain classes of Schlömilch-like infinite series and series that include generalized hypergeometric functions can be calculated in closed form starting from a simple quantum model of a particle trapped inside an infinite potential well and using principles of quantum mechanics. We provide a general framework based on the Hilbert space eigenproblem that can be applied to different exactly solvable quantum models. Obtaining series from normalization conditions in well-defined quantum problems secures their convergence.
Adjustable onset voltages of embedded LiNbO3 domain-wall selectors for large-scale memory integration
Authors: Fan Hao Chen , Shen Bo Wen , Zhang Wen Di , Jiang An Quan
Published: March 2024

A ferroelectric domain-wall memory has dual functionalities, where the volatile interfacial domain nearby the electrode can function as an embedded selector in contrast to the nonvolatile domain within an inner cell for information storage. However, most of crossbar memories require independent adjustments of the onset voltage of the selector and the coercive voltage of the inner domains at the same node fabrication technology. Here, we fabricated a LiNbO3 mesa-like domain-wall device to touch two top-to-top triangular-like Cu side electrodes. The readout wall current is more than 40 μA in write time as short as 20 ns. With the reduction of the apex angle of the Cu electrode from 180° to 30°, the onset voltage increases continuously from 0.68 to 3.05 V irrespective of the coercive voltage along with the improvement of polarization retention. The underlying physics is discussed on thickening of an effective interfacial layer projected along the applied electric-field direction. This finding enables the crossbar connection of high-density ferroelectric domain-wall memory.
Vertical water entry of a cylinder considering wind and linearly sheared flow effect: A numerical investigation
Authors: Yuan Hong-Tao , Sun Jia-Yu , Sun Shi-Li , Zhang Zhao-Fei , Ren Hui-Long
Published: March 2024

Objects entering water is a complex multiphase flow event that exhibits nonlinear and transient characteristics. This study examines the impact cavities, multiphase flow characteristics, and motion behaviors of a cylinder during vertical water entry, considering different flow and entry velocities. A three-dimensional model was carried out using OpenFOAM® framework, taking into account the effects of wind and linearly sheared flow through newly customized initial and boundary conditions. The overset mesh technique was applied to capture the water entry trajectories of the moving cylinder. Numerical results for the cavity evolution and cylinder motion behaviors were validated against published laboratory tests. The cavity closure patterns were classified into four categories based on the evolution characteristics, which were found to be more complex than those observed under calm water and uniform current conditions. Furthermore, the rapid closure of the splash dome results in a unique cavity flow phenomenon, which creates a suction air channel. The velocities of the flow and water entry have a noticeable impact on the closure modes and time of the cavity. This, accordingly, affects the motion characteristics of the cylinder, as well as the evolution of the velocity field, pressure field, and vortex structures.
Enhanced linear polarization of GaN-based Micro-LED via rational chip sidewall engineering
Authors: Zhan Huming , Cao Peng , Huang Jinpeng , Liu Zhiqiang , Yi Xiaoyan , Wang Junxi , Li Jinmin , Wang Liancheng
Published: March 2024

Micro-light-emitting diodes (Micro-LEDs) are considered as the most promising display technologies, while 3D display can provide users with an immersive visual experience and represents the cutting-edge display technology. Polarized Micro-LEDs can be used for polarization-based 3D display technology. In our previous work, circularly polarized and linearly polarized Micro-LEDs have been reported, yet the extinction ratio (ER) still needs to be further improved. The high proportion of sidewalls emission of Micro-LED hinders the further improvement of polarization. In this work, we numerically and experimentally investigated an improved linearly polarized Micro-LED via rational sidewall engineering. Our results show that, at a current density of 300 A/cm2, ER of Micro-LED with a sidewall reflector (RLP Micro-LED) for chip diameters of 10, 20, 30, and 40 μm is 15.85, 16.09, 16.20, and 16.21 dB, respectively, demonstrating a 29.38%, 21.56%, 18.9%, and 12.08% increment compared with linearly polarized Micro-LED without reflector (LP Micro-LED). We also found that by adjusting the sidewall tilt angle, the polarization efficiency and ER values of RLP Micro-LED can be further improved. Our study should advance the development and application of Micro-LED, especially for 3D Micro-LED displays.
A novel vector potential random flow generation method for synthesizing divergence-free homogeneous isotropic turbulence with arbitrary spectra
Authors: Li Chao , Chen Lingwei , Wang Jinghan , Zhang Wentong , Wang Xiangjie , Wang Zhuoran , Hu Gang
Published: March 2024

A novel method, known as the vector potential random flow generation (VPRFG) method, is introduced for synthesizing divergence-free homogeneous isotropic turbulence with arbitrary spectra. First, the proposed approach employs the random-flow-generation-based method to create a vector potential field. Subsequent application of the curl operation to this field produces a turbulent flow that inherently satisfies the divergence-free condition. In the formulas of the proposed method, we explicitly impose arbitrary homogeneous isotropic three-dimensional spatial cross-spectral density (CSD) and Taylor's frozen hypothesis. This ensures that the generated turbulence conforms to prescribed statistical characteristics, including energy spectra, one-dimensional spatial power spectral density (PSD), temporal PSD, spatial coherence function, turbulent kinetic energy, and Reynolds stress. Additionally, the theoretical accuracy of the proposed method is validated through numerical examples, employing the von Kármán energy spectrum as the target value. Finally, large eddy simulations of homogeneous isotropic temporal-decaying box turbulence generated by the VPRFG method demonstrate a close alignment with the experimental results.
Raman scattering evolution in temperature-induced ferroelectric phase transition of few-layer NbOCl2
Authors: Huang Muyang , Chen Wei , Luo Siwei , Huang Zongyu , Wang Ziyu , Qi Xiang
Published: March 2024

NbOCl2 is an emerging layered ferroelectric (FE) material with unique photoelectric properties. However, the phonons and thermal properties of NbOCl2 have remained elusive. Here, we report measurements of Raman and second harmonic generation spectrum of NbOCl2 flakes as a function of temperature (80–500 K). All observed Raman modes exhibit temperature-dependent shift. The first-order temperature coefficients of P1, P2, P3, P4, and P5 modes are 0.001 58, −0.005 21, −0.006 44, −0.012 56, and 0.036 75 cm−1 K−1, respectively. Interestingly, the frequency of the P1 mode changes directly from 161 to 156 cm−1 with increasing temperature, which is attributed to the switching between two independent Raman modes (P1H and P1L). The P1H mode is mainly contributed by the FE phase, while the P1L mode is mainly contributed by the antiferroelectric phase. Our results provide a fundamental understanding and analysis of the thermal–phonon coupling properties of few-layer NbOCl2 and promote the deep exploration of the basic physical properties of few-layer NbOCl2, which is crucial for the design and application of NbOCl2-based thermal and optoelectronic devices in the future.
Low phase noise microwave oscillator based on gain driven polariton
Authors: Kim Mun , Zhang Chunlei , Lu Chenyang , Hu Can-Ming
Published: March 2024

Low phase noise oscillators are key building blocks of many high-end microwave systems. This work introduces a phase noise reduction mechanism through a gain driven polariton platform, where coherent coupling is used to suppress frequency distribution around the carrier, effectively reducing the phase noise. The design process for achieving low phase noise performance is outlined, and three prototypes are constructed, all of which feature key components, such as gain-embedded planar microwave cavity, yttrium iron garnet, and magnets. In particular, the first prototype is used to showcase the phase noise reduction mechanism, while the second prototype, a fixed-frequency oscillator working at 3.544 GHz, exhibits phase noise levels of −117 and −132 dBc/Hz at 10 and 100 kHz offset frequencies, respectively. The third prototype offers a tuning range from 2.1 to 2.7 GHz, while maintaining phase noise levels comparable to the second prototype.
Exact analytical solutions for micropolar magnetohydrodynamic flow: Insights into velocity slip and heat transfer characteristics
Authors: Usafzai Waqar Khan , Aly Emad H. , Kim Sangil
Published: March 2024

In this study, we investigate the laminar steady flow of a micropolar fluid along a permeable flexible surface subject to a uniform magnetic field acting normal to the surface, with wall transpiration and velocity slip at the surface. This analysis yields multiple exact solutions for the stretching/shrinking sheet, offering insights into the complex dynamics of the fluid–surface interaction. In addition, to enhance the realism of our model, we incorporate a power-law temperature distribution, providing a comprehensive understanding of the temperature profile in the context of the micropolar fluid flow. The multiplicity and existence of solutions in special cases are presented for both stretching and shrinking sheets. In particular, a unique solution is found for the stretching sheet in the cases of both suction and injection while dual solutions exist for the shrinking sheet over the range μ>μc in suction, and no solution exist for the injection. For the skin friction, dual solutions appear in the region 0≤a≤ac, but single solution exists for a<0. Furthermore, dual solutions are found for the heat transfer gradient in the regions −∞≤a≤ac and μc≤μ≤∞. Moreover, this research contributes to the broader comprehension of fluid dynamics on flexible surfaces and their intricate thermal behaviors.
Optically tunable mode-locked fiber laser using long-period grating coated with multiwall carbon nanotubes
Authors: Jiang Chen , Wan Ying , Yun Ling , Ma Yuehui , Chen Siyu , Sun Bing , Dai Lilong , Mou Chengbo , Liu Yunqi , Zhang Zuxing
Published: March 2024

We demonstrate an optically tunable mode-locked fiber laser using long-period fiber grating (LPFG) coated with multi-walled carbon nanotubes (CNTs). The multi-walled CNTs can absorb light to convert it into thermal energy, and the resonance wavelength of the grating can be easily turned by varying the external modulated light power. This multi-walled CNT coated LPFG-based all-optical fast and efficient spectrum tunable filter enables continuous tuning of the central wavelength of the laser by manipulating the loss of the mode-locked laser, ensuring the stability of the mode-locking state. In the absence of modulated light on multi-walled CNTs, the soliton laser could generate 890 fs pulses at 1546.7 nm with a spectrum bandwidth of 3.26 nm and a signal-to-noise ratio of 73.1 dB. Through adjustment of the pump power of the modulation light on multi-walled CNTs, the mode-locked fiber laser can be continuously tuned from 1546.71 to 1563.15 nm. The response time of the optically tunable system was measured to be in the order of hundreds of milliseconds. The presented optical tuning filter shows great potential in the fiber laser system, offering a repeatable, straightforward, and rapidly responsive laser tuning technique.
Theoretical and experimental OD-stretch vibrational spectroscopy of heavy water
Authors: Takayama Tetsuyuki , Otosu Takuhiro , Yamaguchi Shoichi
Published: March 2024

In view of the current situation in which the OD-stretch vibrational spectra have been scarcely computed with non-polarizable rigid D2O models, we investigate the IR and Raman spectra of D2O by using a newly-reported model TIP4P/2005-HW. From the comparison between the calculations and experimental data, we find the excellent performance of TIP4P/2005-HW for vibrational spectroscopy of D2O in the same manner as TIP4P/2005 for H2O, although one may still conveniently employ an alternative method that regards OH as putative OD to calculate the OD-stretch spectra with similar quality from TIP4P/2005 trajectories. We also demonstrate that the appropriate setting for the spectral simulation of D2O under the time-averaging approximation reflects the slower dynamics (i.e., slower motion of translation and rotation due to the heavier mass and stronger hydrogen bond) of D2O than H2O. Moreover, we show from the theoretical calculations that the established interpretation of the OH-stretch spectra of H2O is finely applicable to the OD-stretch of D2O.
The dorsomedial prefrontal cortex prioritizes social learning during rest
Authors: Jimenez Courtney A. , Meyer Meghan L.
Published: March 2024

Sociality is a defining feature of the human experience: We rely on others to ensure survival and cooperate in complex social networks to thrive. Are there brain mechanisms that help ensure we quickly learn about our social world to optimally navigate it? We tested whether portions of the brain’s default network engage “by default” to quickly prioritize social learning during the memory consolidation process. To test this possibility, participants underwent functional MRI (fMRI) while viewing scenes from the documentary film,
Samsara
. This film shows footage of real people and places from around the world. We normed the footage to select scenes that differed along the dimension of sociality, while matched on valence, arousal, interestingness, and familiarity. During fMRI, participants watched the “social” and “nonsocial” scenes, completed a rest scan, and a surprise recognition memory test. Participants showed superior social (vs. nonsocial) memory performance, and the social memory advantage was associated with neural pattern reinstatement during rest in the dorsomedial prefrontal cortex (DMPFC), a key node of the default network. Moreover, it was during early rest that DMPFC social pattern reinstatement was greatest and predicted subsequent social memory performance most strongly, consistent with the “prioritization” account. Results simultaneously update 1) theories of memory consolidation, which have not addressed how social information may be prioritized in the learning process, and 2) understanding of default network function, which remains to be fully characterized. More broadly, the results underscore the inherent human drive to understand our vastly social world.
SORI: A softness-rendering interface to unravel the nature of softness perception
Authors: Mete Mustafa , Jeong Haewon , Wang Wei Dawid , Paik Jamie
Published: March 2024

Tactile perception of softness serves a critical role in the survival, well-being, and social interaction among various species, including humans. This perception informs activities from food selection in animals to medical palpation for disease detection in humans. Despite its fundamental importance, a comprehensive understanding of how softness is neurologically and cognitively processed remains elusive. Previous research has demonstrated that the somatosensory system leverages both cutaneous and kinesthetic cues for the sensation of softness. Factors such as contact area, depth, and force play a particularly critical role in sensations experienced at the fingertips. Yet, existing haptic technologies designed to explore this phenomenon are limited, as they often couple force and contact area, failing to provide a real-world experience of softness perception. Our research introduces the softness-rendering interface (SORI), a haptic softness display designed to bridge this knowledge gap. Unlike its predecessors, SORI has the unique ability to decouple contact area and force, thereby allowing for a quantitative representation of softness sensations at the fingertips. Furthermore, SORI incorporates individual physical fingertip properties and model-based softness cue estimation and mapping to provide a highly personalized experience. Utilizing this method, SORI quantitatively replicates the sensation of softness on stationary, dynamic, homogeneous, and heterogeneous surfaces. We demonstrate that SORI accurately renders the surfaces of both virtual and daily objects, thereby presenting opportunities across a range of fields, from teleoperation to medical technology. Finally, our proposed method and SORI will expedite psychological and neuroscience research to unlock the nature of softness perception.
Multilevel transcrustal magmatic system beneath the Geysers-Clear Lake area
Authors: Li Tianjue , Wu Shucheng , Tong Ping
Published: March 2024

Magmatism in the Quaternary Clear Lake volcanic field (CLVF), with its youngest eruption having only occurred c. 10 ka ago, is commonly invoked as the heat source for the world’s largest commercial geothermal reservoir, The Geysers, in northern California. A shallow silicic magma reservoir in the upper-middle crust has been discovered for some time, but the location and mechanism of a potential deep mafic magma reservoir have remained elusive. Here, we present a seismic tomographic model that images the entire crustal column, clearly revealing a multilevel transcrustal magmatic system beneath the Geysers-Clear Lake area. Upwelling melts from the mantle traverse across the crust-mantle boundary and accumulate in the lower crust underneath the southeastern part of Clear Lake, resulting in a hot Moho in between. Mafic melts primarily ascend westward due to the extensional regime in the west and physical barrier effect from the overlying rigid ophiolite fragment, ultimately forming a shallow silicic magma reservoir underlying and heating The Geysers geothermal field. In addition, this study also links compositionally diverse volcanism in a continental setting to differentiation in a multilevel transcrustal magmatic system.
Deforestation impacts soil biodiversity and ecosystem services worldwide
Authors: Qu Xinjing , Li Xiaogang , Bardgett Richard D. , Kuzyakov Yakov , Revillini Daniel , Sonne Christian , Xia Changlei , Ruan Honghua , Liu Yurong , Cao Fuliang , Reich Peter B. , Delgado-Baquerizo Manuel
Published: March 2024

Deforestation poses a global threat to biodiversity and its capacity to deliver ecosystem services. Yet, the impacts of deforestation on soil biodiversity and its associated ecosystem services remain virtually unknown. We generated a global dataset including 696 paired-site observations to investigate how native forest conversion to other land uses affects soil properties, biodiversity, and functions associated with the delivery of multiple ecosystem services. The conversion of native forests to plantations, grasslands, and croplands resulted in higher bacterial diversity and more homogeneous fungal communities dominated by pathogens and with a lower abundance of symbionts. Such conversions also resulted in significant reductions in carbon storage, nutrient cycling, and soil functional rates related to organic matter decomposition. Responses of the microbial community to deforestation, including bacterial and fungal diversity and fungal guilds, were predominantly regulated by changes in soil pH and total phosphorus. Moreover, we found that soil fungal diversity and functioning in warmer and wetter native forests is especially vulnerable to deforestation. Our work highlights that the loss of native forests to managed ecosystems poses a major global threat to the biodiversity and functioning of soils and their capacity to deliver ecosystem services.
Decision-making in the translation of proper-name allusions
Authors: Ren Haimeng
Published: March 2024

As an intertextual and culture-specific expression, allusion activates two texts simultaneously, embedding them
with intended meaning from the source culture but not necessarily in the target culture. In the context of L1 translation being
the majority, allusions can be puzzles that cause “cultural bumps” for translators unfamiliar with the source culture and
language. It is a concern whether translators can accurately and appropriately handle allusions, e.g., proper-name and key-phrase
allusions. This paper focused on the novice translator’s utilization of translation strategies in both directions of translation
to find out how they deal with proper-name allusions and what might influence their choice of strategies. The results suggest that
the translators have distinct preferences for the strategies used to translate proper-name allusions in both directions of
translation. The findings further identified potential factors that motivated the novice translators’ decision-making process.
They revealed their translation competence and awareness that may influence the decision-making of translators handling
proper-name allusions.