bluuebunny/crossref_metadata_2025 huggingface dataset:
Electrostatically embedded symmetry-adapted perturbation theory
Authors: Glick Caroline S. , Alenaizan Asem , Cheney Daniel L. , Cavender Chapin E. , Sherrill C. David
Published: October 2024

Symmetry-adapted perturbation theory (SAPT) is an ab initio approach that directly computes noncovalent interaction energies in terms of electrostatics, exchange repulsion, induction/polarization, and London dispersion components. Due to its high computational scaling, routine applications of even the lowest order of SAPT are typically limited to a few hundred atoms. To address this limitation, we report here the addition of electrostatic embedding to the SAPT (EE-SAPT) and ISAPT (EE-ISAPT) methods. We illustrate the embedding scheme using water trimer as a prototype example. Then, we show that EE-SAPT/EE-ISAPT can be applied for efficiently and accurately computing noncovalent interactions in large systems, including solvated dimers and protein–ligand systems. In the latter application, particular care must be taken to properly handle the quantum mechanics/molecular mechanics boundary when it cuts covalent bonds. We investigate various schemes for handling charges near this boundary and demonstrate which are most effective in the context of charge-embedded SAPT.
A compressible semi-resolved computational fluid dynamics-discrete element method coupling model for fluid–solid systems with heat transfer
Authors: Li Peng , Wang Zhiying , Zhang Yan , Ren Wanlong , Zhang Xuhui , Lu Xiaobing
Published: October 2024

Compressible particle-laden systems are widely present in various natural phenomena and engineering applications. This study focuses on developing a compressible semi-resolved computational fluid dynamics-discrete element method (CFD-DEM) coupling model with heat transfer. The model can simulate gas–solid and liquid–solid systems across a range of dilute to dense patterns. A semi-resolved model is developed by combining the diffusion-based smoothing method and the volume-averaged weighted function interpolation method, removing the restriction of the grid size to particle diameter ratio in unresolved models. The volume-averaged Navier–Stokes equation is introduced for variable density flows in the fluid phase. All closed terms and assumptions are discussed. Special attention is paid to the improved energy conservation equation for the fluid phase and the modified pressure Poisson equations that are suitable for high-speed thermal particulate flows. Particle motion is tracked using DEM, which considers the translation, rotation, collision, and heat transfer processes of the particles. The numerical simulation results are compared with several experimental findings, validating the effectiveness of the compressible CFD-DEM coupling model. The proposed model introduces new ideas and methods for investigating the mechanisms and engineering applications of compressible fluid–solid systems.
Transient response of discrete partial blockages in laminar pressurized flow: Insights into pressure and velocity variations by Computational Fluid Dynamics
Authors: Martins Nuno M. C. , Covas Dídia I. C. , Brunone Bruno , Meniconi Silvia , Capponi Caterina
Published: October 2024

Understanding the interaction between pressure waves and partial blockages in pipe systems is crucial for enhancing noninvasive detection methods based on the execution of transient tests. Although laboratory and one-dimensional numerical models have also provided valuable results from the practical point of view, analyzing the transient response of partial blockages in terms of local flow field characteristics is of great interest. This paper examines the transient response in laminar flow conditions of partial blockages by using a Computational Fluid Dynamics model. In particular, the time history of pressure and local velocity of transient events is examined during the early phase characterized by the first pressure wave reflected by the partial blockage. Laminar conditions are chosen for their minimal risk in real pipe systems as they give rise to small overpressures. The behavior of discrete partial blockages at two locations is analyzed in detail, with a pipe with no blockage scenario as a reference. Simulations of discrete partial blockages with different severity confirm that the reflected pressure wave contains enough information for locating and characterizing partial blockages. The obtained results provide critical insights for the organization of transient tests toward the detection of partial blockages.
Low driving voltage and high reliability 1.54 μm electroluminescence from SnO2:Er/p-Si heterostructured devices via energy transfer effect
Authors: Wu Yunfeng , Pang Houwei , Wang Yuan , Lin Sichen , Wang Lei , Yang Deren , Li Dongsheng
Published: October 2024

Erbium-doped SnO2 films and devices are fabricated on silicon substrates, and the 1.54 μm emission of erbium ions is realized via energy transfer from the SnO2 host. It is found that the luminescence intensity for SnO2:Er film can be enhanced, by increasing the optical activity and transition probability of Er3+ ions with fluorine codoping. Moreover, the device prepared by the fluorine codoped SnO2 film presents a low turn-on voltage of 1.6 V and an onset electric field of 0.18 MV/cm. The unpackaged device operated for 1028h in the atmosphere, then continued to function at 40 °C/30% RH during 1003 h, with less than 10% optical power attenuation. Through further optimizing the preparation process, the optimal device exhibits an optical power density of 38.5 μW/cm2 at 1.55 μm, due to the improved crystalline quality together with the number of sensitizers. This work demonstrates the practical application potential in silicon-based light sources from erbium-doped SnO2 devices.
Deep learning-based super-resolution acoustic holography for phased transducer array
Authors: Lu Qingyi , Zhong Chengxi , Liu Qing , Su Hu , Liu Song
Published: October 2024

Acoustic holography (AH) is a technique with significant potential in realms, such as biomedicine, industry, and augmented reality. The implementation of acoustic holograms can be realized by a passive approach or active ones. Although the passive approach (by a 3D printer) can achieve high-quality acoustic field generation, it is constrained by high manufacturing costs and static field control. On the contrary, the active approach with a phased transducer array (PTA) as the latest technique stands out since it supports dynamic, flexible, and reconfigurable acoustic field generation. However, current PTA-based AH techniques face the drawback of inferior acoustic field fineness due to the Spatial Bandwidth Product (SBP) limit of PTA, which hinders the application of PTA in precise tasks, such as neural electrodes and microfluidics control. To address this issue, we propose a super-resolution acoustic holography (SRAH) method inspired by the concept of super-resolution in ultrasonic imaging and computer vision, by which we can generate acoustic fields reaching the physical diffraction limit of acoustic waves regardless SBP of PTA. In other words, this method enables high-SBP acoustic field generation with low-SBP PTA. The method is based on self-supervised learning, integrating a generative adversarial network and a physical model of acoustic wave propagation, specifically the linear accumulation method. Both simulation and experimental results demonstrate that the proposed method can generate high-fidelity acoustic fields suitable for intricate tasks with low-SBP PTA. Moreover, the performance of the algorithm improves as the target SBP increases. Therefore, the proposed SRAH method shows great potential for applications requiring elaborate manipulation.
Dynamics of stochastic differential equations with memory driven by colored noise
Authors: Liu Ruonan , Caraballo Tomás
Published: October 2024

In this paper, we will show two approaches to analyze the dynamics of a stochastic partial differential equation (PDE) with long time memory, which does not generate a random dynamical system and, consequently, the general theory of random attractors is not applicable. On the one hand, we first approximate the stochastic PDEs by a random one via replacing the white noise by a colored one. The resulting random equation does generate a random dynamical system which possesses a random attractor depending on the covariance parameter of the colored noise. On the other hand, we define a mean random dynamical system via the solution operator and prove the existence and uniqueness of weak pullback mean random attractors when the problem is driven by a more general white noise.
Self-organizing maps of unbiased ligand–target binding pathways and kinetics
Authors: Callea Lara , Caprai Camilla , Bonati Laura , Giorgino Toni , Motta Stefano
Published: October 2024

The interpretation of ligand–target interactions at atomistic resolution is central to most efforts in computational drug discovery and optimization. However, the highly dynamic nature of protein targets, as well as possible induced fit effects, makes difficult to sample many interactions effectively with docking studies or even with large-scale molecular dynamics (MD) simulations. We propose a novel application of Self-Organizing Maps (SOMs) to address the sampling and dynamic mapping tasks, particularly in cases involving ligand flexibility and induced fit. The SOM approach offers a data-driven strategy to create a map of the interaction process and pathways based on unbiased MD. Furthermore, we show how the preliminary SOM mapping is complementary to kinetic analysis, with the employment of both network-based approaches and Markov state models. We demonstrate the method by comprehensively mapping a large dataset of 640 μs of unbiased trajectories sampling the recognition process between the phosphorylated YEEI peptide and its high-specificity target lck-SH2. The integration of SOM into unbiased simulation protocols significantly advances our understanding of the ligand binding mechanism. This approach serves as a potent tool for mapping intricate ligand–target interactions with unprecedented detail, thereby enhancing the characterization of kinetic properties crucial to drug design.
Comparative study of Eyring–Powell fluid flow with temperature-dependent viscosity in roll-rotating systems: An analytic, numeric, and machine learning approach
Authors: Ali Fateh , Hou Yanren , Feng Xinlong , Odeyemi J. K. , Usman M. , Ahmad Riaz
Published: October 2024

The roll coating process is broadly employed in the manufacturing of wallpapers, protection of fabrics and metals, wrapping, adhesive tapes, x-ray and photographic films, books and magazines, beautification, magnetic records, film foils, coated paper, etc. This study proposes a new framework for analyzing non-Newtonian fluid flow between co-rotating rolls at identical speed and size. The framework combines analytical, numerical, and computational methods powered by artificial neural networks. A key aspect of the model is the incorporation of temperature-dependent viscosity, allowing us to investigate its theoretical influence on various flow characteristics and relevant engineering parameters. To achieve this, we derive non-dimensionalized mass and momentum balance equations using appropriate transformations and lubrication approximation theory. The analytic expression for velocity distribution, temperature, pressure gradient, pressure fields, and flow rate is achieved by utilizing the perturbation method. The numerical solutions using the collocation method based on Hermite functions and the boundary value problem built-in method are also obtained. After deriving these expressions, we calculate engineering quantities including the Nusselt number, streamline, power input needed to drive both cylinders, and the roll separation force. The impacts of emerging parameters on all quantities of interest are illustrated using graphs and tables. It is interesting to mention that an increase in the non-Newtonian parameter increases the velocity but in the increase in the Vogel viscosity parameter, the velocity decreases. Furthermore, the correctness of the present work is observed by comparing analytic, numeric solutions and previously published work, and observed good agreement. To obtain approximate solutions for various flow scenarios within the proposed model, we employ a supervised neural network solver with Levenberg–Marquardt backpropagation (LMBP-SNNs) for testing, validation, and training. This approach utilizes the mean squared error (MSE) to adjust the network parameters. The efficiency of the proposed LMBP-SNN solver is validated through a combination of comparative analyses, performance studies based on MSE outputs, and visualizations of regression errors. The performance on MSE has been shown for the velocity profiles of the developed model about 9.174 × 10−12, 4.1029 × 10−12, 4.5997 × 10−12, and 2.8300 × 10−13. This study addresses a gap in the existing literature by exploring the rheological properties of the Eyring–Powell fluid model and integrating numerical methods along with machine learning techniques in the forward roll coating process.
Dipropyl sulfide optimized buried interface to improve the performance of inverted perovskite solar cells
Authors: Wei Jiali , Wang Xin , Yang Haoran , Guo Jingwei , Li Tiantian , Zhu Chengjun , Hou Fuhua
Published: October 2024

Recently, [4–(3,6-dimethyl-9H-carbazol-9-yl)butyl] phosphonic acid (Me-4PACz) has garnered significant attention as a highly effective passivation layer for NiOx. However, the Me-4PACz passivation layer shows low wettability to perovskite precursors, hindering the crystallization of perovskite. Moreover, Me-4PACz does not uniformly and completely cover NiOx, failing to achieve an optimal passivation effect. The presence of high-valence-state Ni species and reactive hydroxyls on the NiOx film surface leads to perovskite degradation. To address this, dipropyl sulfide (DPS) was incorporated into a solution of Me-4PACz. This approach not only enhances the wettability of Me-4PACz, facilitating the growth of larger perovskite grains but also enables Me-4PACz to form a homogeneous passivation layer with strong coverage. This effectively prevents direct contact between NiOx and perovskite films. Additionally, DPS interacts with reactive hydroxyls, removing them from the NiOx surface and mitigating the deprotonation reaction of MA/FA in perovskite. Furthermore, DPS is reducible, which helps in reducing high-valent Ni (Ni4+), thereby decreasing redox reactions at the interface. As a result, the optimized perovskite solar cells with DPS achieved a power conversion efficiency (PCE) of 22.29%, higher than the control device of 20.52%. Moreover, the DPS-decorated device demonstrated excellent stability, retaining over 80% of its initial PCE value, compared to only 60% retention in the control device. This work modified the buried interface and offers valuable insights for subsequent similar studies.
Numerical study on detonation initiation process in a reverse ignition boosted detonation chamber
Authors: Wang Zhiwu , Xiao Jingtao , Zhang Yang , Long Hao , Zhang Zixu , Li Minqiang , Zhan Yimin
Published: October 2024

To achieve efficient detonation initiation within a short distance and time, an innovative ignition approach based on hot jet ignition and shock wave focusing within a reverse ignition boosted detonation chamber configuration is proposed. Two-dimensional numerical simulations are employed to comprehensively investigate the mechanisms of detonation initiation in H2–air mixtures. The intricate evolutionary processes involving flame acceleration, deflagration to detonation transition, and detonation wave propagation are meticulously analyzed. The numerical investigation reveals that the ignition and propagation processes within this configuration can be categorized into four distinct stages: the ignition and initial flame development stage, vortex development and shock reflection stage, rapid flame acceleration and detonation transition stage, and detonation wave propagation and stabilization stage. These stages correspond to specific sections within the detonation chamber, namely, the ignition chamber, shock reflection section, narrow channel, and main detonation chamber. Flame acceleration is driven by a synergy of wall interactions, vortex entrainment, stretching, and shock reflection. Furthermore, a positive feedback loop between the flame, vortices, and the chamber walls amplifies flame acceleration significantly. The critical moment of initiation hinges upon the convergence of the flame front with the leading shock wave. The formation of large- and small-scale cellular structures under different detonation mechanisms further facilitates stable propagation.
Influence of wettability on drag reduction performance during turbulent flow
Authors: Zhu Jingfang , Tang Xubing , Jia Haiyang , Han Longxiang , Lin Cunguo , Zhang Jinwei , Li Longyang
Published: October 2024

The wettability of lubricant oil produces a velocity slip at the water–lubricant oil interface when the lubricant oil contacts the rectangular microgroove, leading to a reduction in the friction resistance at the boundary wall. However, lubricant oil is highly susceptible to changes in external shear force and can escape from the rectangular microgroove, degrading its slippery properties. This study investigated the influence of wettability and structure width on the stability and drag reduction performance of lubricant oil via simulation. The results indicated that lubricant oil stability is related to wettability and structural width. The lubricant oil remained stable at contact angles of 1° and 150° and a width of 0.4 mm. Based on slip velocity, the maximum drag reduction at a width of 0.6 mm in a turbulent environment was 13.4%. Our findings could provide valuable insights into surface design using lubricant oil, helping researchers avoid detrimental designs and enhance sustainable drag reduction performance.
Experimental analysis of flow characteristics in S-shaped ducts at low speeds
Authors: Jiang Fan , Kontis Konstantinos , White Craig
Published: October 2024

This study investigates the flow characteristics within an S-shaped duct at low speeds and examines the impact of varying lengths of upstream and downstream extensions on the internal flow field. The experimental setup includes an S-shaped duct model and an axial fan, with the fan positioned downstream to regulate flow velocity within the duct. Taking the S-duct throat as the reference point, the velocity range under investigation spans from 0.06 to 0.15 Mach. Measurements are taken in a region between the S-shaped duct and the fan using a traverse system to capture aerodynamic interface plane flow parameters. Additionally, wall static pressure measurements are utilized to characterize the flow field within the duct. Results indicate that although flow velocity has a relatively minor effect on the flow pattern inside the S-duct, it can cause a significant fluctuation of the wall static pressure coefficient. In contrast, the influences of the upstream and downstream extensions on the flow pattern inside the S-duct are more critical. Specifically, the upstream extension directly impacts the stall region at the duct's bottom and significantly increases the inlet boundary thickness, while the downstream extension determines the flow modes of the secondary flow on the exit. When both upstream and downstream extensions are sufficiently long, the influence of flow velocities on the flow pattern inside the S-duct can be almost eliminated.
A rapid prediction method for water droplet collection coefficients of multiple airfoils based on incremental learning and multi-modal dynamic fusion
Authors: Xia Yuhao , Li Tingyu , Wang Qiang , Yue Jing , Peng Bo , Yi Xian
Published: October 2024

The calculation of the water droplet collection coefficient (WDCC) is a crucial step in the numerical study of aircraft icing and the iterative design of anti-icing and deicing systems. Rapid and efficient methods for predicting WDCC are essential for enhancing the efficiency of icing numerical calculations and accelerating the design cycle of these systems. The existing prediction methods are inefficient and fail to meet the real-time requirements of engineering applications. This paper proposes a rapid prediction method for the WDCC for multiple airfoils utilizing deep learning techniques. The method takes enhanced airfoil section images and icing condition parameters as inputs and WDCC as output. A deep neural network prediction model, IncDynamicFusion, for sustainable learning is established by integrating a multimodal dynamic fusion method with an improved iCaRL method (incremental classifier and representation learning). Numerical experimental results demonstrate that the proposed model can quickly and effectively predict the WDCC of multiple airfoils.
Bounds to the Basset–Boussinesq force on particle laden stratified flows
Authors: Reartes Christian , Mininni Pablo D.
Published: October 2024

The Basset–Boussinesq force is often perfunctorily neglected when studying small inertial particles in turbulence. This force arises from the diffusion of vorticity from the particles and, since it depends on the particles' history, complicates the dynamics by transforming their equations of motion into integrodifferential equations. However, this force is of the same order as other viscous forces acting on the particles, and beyond convenience, the reasons for neglecting it are unclear. This study addresses the following question: Under what conditions can the Basset–Boussinesq force be neglected in light particles in geophysical flows? We derive strict bounds for the magnitude of the Basset–Boussinesq force in stably stratified flows, in contexts of interest for geophysical turbulence. The bounds are validated by direct numerical simulations. The Basset–Boussinesq force is negligible when a buoyancy Stokes number Sb=Nτp is small, where N is the flow Brunt–Väisälä frequency and τp is the particle's Stokes time. Interestingly, for most oceanic particles this force may be negligible. Only for very strong stratification, or for particles with very large inertia, this force must be considered in the dynamics.
Hydrodynamic characteristics of the water-entry of a structure colliding with the floating ice
Authors: Lu Lin , Yang Zhe , Qi Xiaobin , Zhou Yu , Chen Kaimin , Li Qiang
Published: October 2024

A two-way fluid–structure interaction (FSI) method for the water-entry process of a structure colliding with the floating ice is established. The two-way FSI method is validated by a collision experiment between an ice floe and a cylinder. Subsequently, the cavity evolution, hydrodynamic load, and motion characteristics during the water-entry process of the structure colliding with the floating ice are investigated. In addition, the influence of different distances between the axis of the structure and the edge of the floating ice on the water-entry characteristics is conducted. The results show that after the collision, the outward flipping motion of the floating ice forms the floating ice cavity, promotes the expansion of the structure cavity, and delays the closure time of the cavity, resulting in a significant increase in the size of the structure cavity compared to the ice-free environment; the effect is further exacerbated by an increase in the distance between the structure and the floating ice. Moreover, under the floating ice environment, the fluctuation and amplitude of the hydrodynamic load on the structure and the total horizontal displacement of the structure are reduced. The interaction force generated by the collision between the structure and floating ice becomes the main reason affecting the motion trajectory. As a result of the collision with the floating ice, the velocity attenuation is faster than that under the ice-free environment.
Thermal transport across armchair–zigzag graphene homointerface
Authors: Wu Shuai , Kang Dongdong , Yu Xiaoxiang , Dai Jiayu
Published: October 2024

Obstructed thermal transport across interfaces is the main cause of serious heat dissipation issues in electronics. Analogous to heterointerface in heterostructure, homointerface is another widely existing interface, such as grain boundary (GB) in polycrystal. Through nonequilibrium molecular dynamics simulations, we investigated the thermal transport across armchair–zigzag graphene GB homointerfaces and reported the ultrahigh interfacial thermal conductance (ITC) in the order of 10 GW/m2K induced by well-matched phonons, much larger than those of heterointerfaces with mismatched phonons. By comparing four homointerfaces with different interfacial atomic structures, we pointed out a significant underestimation of ITC in previous works commonly using the “fly-head” structure. At 300 K, the ITC of the homointerface with the most energetically favorable structure is 30% higher than that of the “fly-head” homointerface. Spectral decomposition of ITC demonstrated suppressed phonon transmission in the full frequency range in the “fly-head” homointerface. Atom-resolved analysis unraveled that the “fly-head” homointerface shows aggregated stress distribution and thus significant modification in atomic vibrations near the interface, leading to a poorer match of phonon density of states. Furthermore, we found that the inelastic phonon transport is overwhelmed by elastic processes at the homointerface, as evidenced by the temperature independence of ITC at elevated temperatures and the consistent spectral heat flux of the interface and bilateral regions. This work provides insight into the microscopic thermal transport mechanism of homointerfaces.
A path-specific isentropic exponent for non-ideal compressible fluids
Authors: Wang Jinhong , Cao Teng , Martinez-Botas Ricardo
Published: October 2024

Isentropic processes are crucial in engineering as they represent idealized processes and serve as reference conditions for thermodynamic analyses. Existing methods for calculating isentropic processes in non-ideal fluids are either too slow for practical engineering applications [equation of state (EOS) approach] or inaccurate (classic modified polytropic isentrope equation: Pvκ=Const. where exponent κ is the isentropic expansion coefficient). This paper proposes a novel isentrope equation, Pvλ=Const., with a path-specific exponent λ correcting for κ variation in generic non-ideal fluid isentropic processes. The benefit of this approach is that it maintains the isentrope equation's polytropic form, so that the explicit isentropic relations can be derived, enabling straightforward and rapid calculations and a better physical understanding. Using supercritical carbon dioxide as the fluid to test the hypothesis, the proposed isentropic relations accurately calculate the stagnation state within 2% of the exact EOS calculation, whereas the classic isentropic relations have errors up to 50%. Additionally, the fitted λ function is explicit and can calculate the stagnation state approximately 15–20 times faster than the EOS approach. Moreover, the results of two other non-ideal fluids, hexamethyldisiloxane and R-143a, are included to prove the robustness and general applicability of the proposed equations. This method strikes a balance between accuracy, simplicity, and computational speed for calculating isentropic processes in non-ideal fluids, offering greatly simplified expressions for thermodynamics modeling in engineering applications such as turbomachinery reduced-order models and design optimizations.
Boosting predictive accuracy of single particle models for lithium-ion batteries using machine learning
Authors: Olugbade Emmanuel , Park Jonghyun
Published: October 2024

The accuracy of single particle (SP) models for lithium-ion batteries at high C-rates is constrained by lithium concentration gradients in the electrolyte, which affect ionic conductivity, overpotential, and reaction rates. This study addresses these limitations using extreme gradient boosting machine learning (ML). By training our ML model with data from a comprehensive electrochemical (P2D) model and performing sensitivity analysis on key battery parameters, we enhance predictive accuracy. Compared to conventional SP and P2D models under constant current loading, our ML-based SP model achieves similar predictive accuracy to P2D, with significant improvements in computational efficiency. Additionally, the ML-based SP model demonstrates improved predictive accuracy under dynamic loading conditions, providing a practical framework for improving battery management and safety.
Using microfluidics to assess the elongational behavior of low concentration Carbopol solutions upon addition of polyethylene oxide
Authors: Cirillo Andrea Iginio , Gallo Fabiana , Longo Emanuela , Claussen Jan , Guido Stefano , Tomaiuolo Giovanna
Published: October 2024

The exceptional viscosity-modifying and yield stress properties of Carbopol are crucial in various industrial applications, from pharmaceuticals and personal care products to textile and paper. However, Carbopol aqueous solutions, especially in dilute conditions, lack elongational properties, which are essential for numerous applications, such as adhesives and sealants. The combination of different polymers allows for tuning both shear and elongational properties of a solution. This optimization is key to improving product performance and stability, and meeting the specific requirements of a desired application. In this study, we enhance the elongational properties of low concentration Carbopol aqueous solutions by adding polyethylene oxide (PEO) and characterize the resulting solutions using the filament stretching technique in transparent cross-shaped microchannels, where both continuous and dispersed phases are involved. The elongational viscosity is estimated by analyzing the filament thinning of the dispersed phase over time. Our findings indicate that the thinning process becomes more pronounced the more the continuous phase viscosity matches that of the dispersed one. Moreover, adding PEO to a Carbopol solution significantly impacts its elongational behavior, even at low concentrations of both polymers, indicating a synergistic effect between the polymers in modulating the elongational properties.
Numerical simulation of a droplet impact onto a curved liquid film
Authors: Chen Weihao , Guo Yali , Chi Jun , Shen Shengqiang
Published: October 2024

Droplet impinging on liquid film is significant for many industrial processes. In this work, the normal impact of a single droplet on different thickness of concave curved liquid films is simulated. Coupled level set and volume of fluid method is used to capture the dynamics of drop impact and crown spreading. The variation of pressure field of droplets impacting the curved liquid film is investigated. The effect of film thickness and wall curvature on the water crown behavior is studied. With the curvature ratio increasing, the elevation angle of the velocity vector at crown rim increases, and the velocity gradient inside the crown decreases. The increase in curvature ratio also makes the crown sheet incline inward and suppresses the splash. The thickness of liquid film will lead to discrepancies in crown behaviors. The thin film makes the spreading speed of crown rim faster, and the crown top will shrink and splash. With the thickening of the liquid film, the influence of the thickness on the shape and size of the crown weakens. The separation of crown influenced by thin film is also analyzed.
Atomic scale analysis of sub-10 nm implantation of size-selected gold clusters into multilayer graphene
Authors: Tang Sichen , Xiang Jingye , Hu Shengyong , Zuo Zewen , Lu Siqi , Zhao Zixiang , Zhang Yongxin , Zhu Wuwen , Zheng Dong , Hu Kuo-juei , Zhang Minhao , Song Fengqi
Published: October 2024

Here, we report the sub-10 nm implantation of size-selected AuN nanoclusters (N = 20–147) into multilayer graphene with different deposition energy (50–15 000 eV) using a magnetron sputtering cluster beam source. Combined with aberration-corrected scanning transmission electron microscopy, we directly characterize the implantation depth of gold clusters and demonstrate the scaling relations between size, deposition energy, and implantation depth of gold clusters. The time-of-flight secondary ion mass spectrometry analysis can also confirm the possibility of ultra-shallow implantation. The results are further corroborated by molecular dynamics simulations of Au55, which show that at a deposition energy of 15 keV, Au55 penetrates about 4.45 nm in multilayer graphene, consistent with our experimental result of 4.38 nm, i.e., about 13 atomic layers. Our results reveal the possibility of cluster implantation to atomic precision, thus guiding the fabrication of sub-10 nm electronic devices.
Stretchable, enhancement-mode PEDOT:PSS organic electrochemical transistors
Authors: Wang Yan , Liu Dingyao , Bai Jing , Tian Xinyu , Lai P. T. , Zhang Shiming
Published: October 2024

The rise of wearable and implantable bioelectronics necessitates stretchable electronic devices and systems to seamlessly integrate with soft biological environments. Stretchable organic electrochemical transistors (OECTs), based on conducting polymer poly(3,4-ethylenedioxythiophene) doped with polystyrene sulfonate (PEDOT:PSS), have emerged as a promising candidate because of their combined high stability and high transconductance. However, a stretchable, enhancement-mode PEDOT:PSS OECT (SE-OECT) is still missing, limiting the development of complementary and low-power integration systems. In this Letter, we report SE-OECTs. The devices showed typical enhancement-mode transistor behaviors with standby power as low as 0.1 μW while maintaining stable performance after 1000 cyclic tests within 50% strain.
Flow dynamics of the transversely oscillating tapered circular cylinder under vortex-induced vibrations at low Reynolds number
Authors: Verma Mayank , De Ashoke
Published: October 2024

This study numerically investigates the influence of the taper on the flow-induced vibrations of an elastically mounted circular cylinder under vortex-induced vibrations (VIV). The dynamic response of three different taper ratios [TR defined as TR=l/(d2−d1) = 12 (highly tapered cylinder), 20 (medium tapered cylinder), and 40 (low tapered cylinder)], where d1 and d2 are the largest and smallest diameter of the tapered cylinder, respectively, with length l is studied at a fixed Reynolds number [ReD, defined based on the averaged cylinder diameter, D=(d1+d2)/2] of 150. The amplitude and frequency response of the tapered cylinder is characterized by a low mass ratio (defined as the ratio of the total oscillating mass to the displaced fluid mass) of m* = 2 over the wide range of reduced velocity (3≤Ur≤16) covering the full amplitude-response spectrum (based on the oscillation amplitude) of the VIV. The results show the existence of difference in the spanwise shedding of vortices owing to the poor spanwise pressure correlation. The flow field analysis in the wake of the oscillating cylinder reveals the dominance of the three-dimensional structures in the wake (near the top end with the larger diameter) behind the cylinder with the increase in the taper ratio (even at such low ReD where the uniform cylinder exhibits the two-dimensional wake). Also, the tapered cylinder exhibits a wide range of frequency synchronization (i.e., wide lock-in area) compared to the uniform cylinder. Tapering the cylinder results in the shift of the peak of the max oscillation amplitude or, in turn, the shift in the transitioning of the response branches. Further, force decomposition, energy transfer, and phase dynamics are also discussed for the taper cylinders.
Oblique collision of two evaporating drops
Authors: Pal Ashwani Kumar , Zaleski Stéphane , Biswas Gautam
Published: October 2024

Comprehension of the mechanics leading to the outcomes of the drop–drop collisions is essential for several industrial applications, including design of combustion chambers, development of spray drying techniques, agricultural spraying, and spray coating. In the broader context of several areas of applications, the stretching separation as well as transition between the reflexive and the stretching separation are required to be analyzed thoroughly. In this study, collision dynamics of two drops of equal size undergoing head-on and oblique collisions are studied using three-dimensional (3D) numerical simulations. The outcomes of collisions resulting in permanent coalescence, reflexive separation, and stretching separation are analyzed for a set of Weber numbers and impact parameters. The reflexive separation is an outcome of head-on collision for small values of the impact parameter. The stretching separation occurs owing to oblique collisions where the value of the impact parameter is larger. An accurate mass transfer mechanism coupled with the three-dimensional multi-phase simulations is deployed to study the collision outcomes of the evaporating drops for head-on and oblique collision scenarios. Simulations are performed for various levels of superheat between the drops and their surroundings to understand the effect of increasing mass transfer. The velocity field during the collision processes are altered when mass transfer due to evaporation plays an important role. The evolution of energy budgets and liquid volumes for all three collision regimes are presented for various levels of superheat considered in this study.
Relaxation dynamics of a liquid in the vicinity of an attractive surface: The process of escaping from the surface
Authors: Behbahani Alireza F. , Harmandaris Vagelis
Published: October 2024

We analyze the displacements of the particles of a glass-forming molecular liquid perpendicular to a confining solid surface using extensive molecular dynamics simulations with atomistic models. In the vicinity of an attractive surface, the liquid molecules are trapped. Transient localization of liquid molecules near the surface introduces a relaxation process related to the escape of molecules from the surface into the dynamics of the interfacial liquid layer. To describe this process, we analyze several dynamical observables of the confined liquid. The self-intermediate scattering function and the mean-squared displacement of the particles located in the interfacial layer are dominated by the process of escaping from the surface. This relaxation process is also associated with a strong heterogeneity in the mobility of the interfacial particles. The studied model liquid is hydrogenated methyl methacrylate. For the confining wall, we consider different models, namely a periodic single layer of graphene and a frozen amorphous configuration of the bulk liquid (frozen wall). Near graphene, where the liquid molecules form a layered structure and adopt parallel-to-surface orientation, a clear separation between small-scale movements of the molecules near the surface and the process of escaping from the surface is observed. This is reflected in the three-step relaxation of the interfacial layer. However, near the frozen wall, where the liquid molecules do not have a preferential alignment, a clear three-step relaxation is not seen, even though the dynamical quantities are controlled by the process of escaping from the surface.
On the timescales in the chaotic dynamics of a 4D symplectic map
Authors: Cincotta Pablo M. , Giordano Claudia M.
Published: October 2024

In this work, we investigate different timescales of chaotic dynamics in a multi-parametric 4D symplectic map. We compute the Lyapunov time and a macroscopic timescale, the instability time, for a wide range of values of the system’s parameters and many different ensembles of initial conditions in resonant domains. The instability time is obtained by plain numerical simulations and by its estimates from the diffusion time, which we derive in three different ways: through a normal and an anomalous diffusion law and by the Shannon entropy, whose formulation is briefly revisited. A discussion about which of the four approaches provide reliable values of the timescale for a macroscopic instability is addressed. The relationship between the Lyapunov time and the instability time is revisited and studied for this particular system where in some cases, an exponential or polynomial law has been observed. The main conclusion of the present research is that only when the dynamical system behaves as a nearly ergodic one such relationship arises and the Lyapunov and instability times are global timescales, independent of the position in phase space. When stability regions prevent the free diffusion, no correlations between both timescales are observed, they are local and depend on both the position in phase space and the perturbation strength. In any case, the instability time largely exceeds the Lyapunov time. Thus, when the system is far from nearly ergodic, the timescale for predictable dynamics is given by the instability time, being the Lyapunov time its lower bound.
Integrated transfer of large-scale gate dielectric/2D material films for low-power devices
Authors: Tong Tong , Gao Yuan , Liao Kan , Li Weisheng
Published: October 2024

With silicon-based devices nearing the limits of physical miniaturization, the hunt for alternative electronic materials is more critical. Two-dimensional (2D) semiconductors stand out as compelling candidates for future research, owing to their simple vertical integration, efficient carrier modulation, and good compatibility with complementary metal–oxide–semiconductor technology. However, 2D materials with atomic thickness are usually too fragile to maintain their inherent characteristics in the device manufacturing process; thus, interface engineering is crucial to achieve high-performance transistor arrays. In this research, we introduce a damage-free integrated transfer technique for centimeter-scale gate dielectric/2D material stacks, leveraging a water-assisted approach. This method is capable of transferring dielectric layers as thin as 4 nm with exceptional surface smoothness of less than 0.3 nm. The fabrication of MoS2 top-gate transistors with atomically clean and electronically sharp interfaces has resulted in remarkable device performance, including mobility of ∼34 cm2/(Vs), an on/off ratio exceeding 106, and a subthreshold swing as low as 72 mV/dec. Extensive statistical analysis of these large-area devices confirms the potential for high-uniformity, low-power device fabrication. Moreover, the scalability of this technique to various nanomaterials holds promise for advancing large-area damage-free transfer processes and the development of high-performance gate arrays.
Nanozymes for biomedical applications
Authors: Wang Xin , Fang Yutong , Yang Ying-Wei
Published: October 2024

Nanozymes, defined as nanomaterials with intrinsic enzymatic properties, have evoked fundamental new science and offer new paradigm technologies for developing multifunctional diagnostic and therapeutic nanoplatforms. To comprehend the field of nanozymes, this Editorial briefly reviews the significant developments in their design and fabrication, highlighting existing challenges and future perspectives, promoting the further flourishing development of nanozyme-based materials toward superior biomedical applications.
Contributions of nano- and picophytoplankton to the phytoplankton biomass in Saudi Arabian waters of the Arabian Gulf
Authors: Heinle Moritz J. , Flandez Ace V. , Clardy Todd R. , Balkhi Hattan , Qurban Mohammad A.
Published: October 2024

The two smallest size classes of phytoplankton, namely, nano- and picophytoplankton, can play an important role in marine primary production, particularly in warm and nutrient-poor waters. The Arabian Gulf, with its high temperatures, could provide good growth conditions for these two size classes; however, so far, phytoplankton research in the Arabian Gulf has largely focussed on the biggest size class, microphytoplankton. This study presents data on the annual cycle of chlorophyll-a (Chl-a) at three stations in Saudi Arabian waters of the Arabian Gulf, focussing on the contribution of the three phytoplankton size classes to total Chl-a, and identifies environmental parameters affecting these contributions. Whereas dominance of nanophytoplankton was observed during summer, highest contributions of picophytoplankton were found during winter and spring. A close link between nano- and microphytoplankton was noted on the basis of optimum correlation models. The models for both size fractions included photosynthetically active radiation, salinity and phosphate concentration, but with opposing algebraic signs in the two models. By contrast, picophytoplankton was negatively correlated with temperature, indicating that the contribution of this size class could decrease under a future climate-change scenario in the Arabian Gulf.
Selective ligand recognition and activation of somatostatin receptors SSTR1 and SSTR3
Authors: Wang Yujue , Xu Youwei , Wang Yue , Zhang Jie , Chen Lan , He Xinheng , Fan Wenjia , Wu Kai , Hu Wen , Cheng Xi , Yang Guizhu , Xu H. Eric , Zhuang Youwen , Sun Shuyang
Published: October 2024

Somatostatin receptors (SSTRs) exert critical biological functions such as negatively regulating hormone release and cell proliferation, making them popular targets for developing therapeutics to treat endocrine disorders, especially neuroendocrine tumors. Although several panagonists mimicking the endogenous ligand somatostatin are available, the development of more effective and safer somatostatinergic therapies is limited due to a lack of molecular understanding of the ligand recognition and regulation of divergent SSTR subtypes. Here, we report four cryoelectron microscopy structures of G
i
-coupled SSTR1 and SSTR3 activated by distinct agonists, including the FDA-approved panagonist pasireotide as well as their selective small molecule agonists L-797591 and L-796778. Our structures reveal a conserved recognition pattern of pasireotide in SSTRs attributed to the binding with a conserved extended binding pocket, distinct from SST14, octreotide, and lanreotide. Together with mutagenesis analyses, our structures further reveal the dynamic feature of ligand binding pockets in SSTR1 and SSTR3 to accommodate divergent agonists, the key determinants of ligand selectivity lying across the orthosteric pocket of different SSTR subtypes, as well as the molecular mechanism underlying diversity and conservation of receptor activation. Our work provides a framework for rational design of subtype-selective SSTR ligands and may facilitate drug development efforts targeting SSTRs with improved therapeutic efficacy and reduced side effects.
The augmented interpreter
Authors: Gieshoff Anne Catherine , Schuler Martin , Jahany Zaniyar
Published: October 2024

Computer-assisted interpreting (CAI) tools use speech recognition and machine translation to display numbers and
names on a screen or automatically suggest renditions for technical terms. One way to improve the usability of CAI tools may be to
use augmented reality (AR) technology, which allows information to be displayed wherever convenient. Instead of having to look
down at a tablet or a laptop, the interpreter can see the term or number projected directly into their field of vision, allowing
them to maintain their focus on the speaker and the audio input. In this study, we investigated the affordances of AR in
simultaneous interpreting. Nine professional conference interpreters each interpreted two technical talks: one with numerals,
proper nouns and suggestions for technical terms automatically shown on an AR display and the other with an MS Word glossary on a
laptop. The results indicate a hypothetical use case for AR technologies in interpreting but highlight the practical limitations,
such as a lack of comfort in wearing the AR equipment, a lack of ergonomic and intuitive interaction with virtual objects, and
distraction and interference with the interpreting process in the form of additional visual input.