bluuebunny/crossref_metadata_2025 huggingface dataset:
Detailed analysis on primary and secondary break up characteristics of liquid fuel jet in crossflow using homogeneous mixture model and large eddy simulation
Authors: Yun Donggyu , Sung Hong-Gye
Published: November 2024

The detailed breakup characteristics of the liquid jet fuel, Jet-A, in crossflow to various ranges of momentum flux ratios and Weber numbers have been investigated using a high-fidelity compressible multi-phase numerical technique. Multi-phase large eddy simulation with adaptive mesh refinement and Eulerian to Lagrangian transformation are applied to the homogeneous mixture model. The liquid surface instabilities and their frequencies inside the injector orifice are observed and analyzed. Interactions between liquid jet and crossflow result in phenomena such as horse-shoe vortex formation, boundary separation, liquid trailing, and counter-rotating vortex pair. Liquid column breakup characteristics and wave structures are analyzed from both temporal and spatial viewpoints. The Sauter mean diameter distribution and cumulative distributions of droplets resulting from secondary breakup are presented, along with the droplet size distribution derived from the momentum flux ratio and Weber number. Several engineering models, including the instability frequencies, the breakup length, and the penetration depth, are proposed in terms of the momentum flux ratio and Weber number, providing valuable insights for injector and combustor design.
Bismuth-based ternary chalcogenides Pt3Bi4X9 (X = S, Se) as promising thermoelectric materials
Authors: Zeng Hongli , Yan Yanci , Wu Hong , Chen Peng , Wang Cong , Luo Xiaobing , Wu Dandan , Ding Guangqian
Published: November 2024

We present a theoretical investigation of thermoelectric transport properties of bismuth-based ternary chalcogenides Pt3Bi4X9 (X = S, Se), which has low thermal conductivity and promising zT as discovered in a recent experiment [Wang et al., J. Am. Chem. Soc. 146, 7352 (2024)], using density functional theory combined with the Boltzmann transport equation within rigid band approximation. We find that the high density of states of valence bands near the Fermi level yields high p-type Seebeck coefficient. The lower effective mass of electron in Pt3Bi4S9 leads to high mobility and long relaxation time, and hence the high n-type electrical conductivity. In contrast, the effective mass of electron is much higher than that of hole in Pt3Bi4Se9 due to the flatted conduction band, which in turn gives rise to higher p-type electrical conductivity. As a result, the p-type zT is much higher than n-type in Pt3Bi4Se9, with an optimal value of 0.5 at 300 K. Considering the experimental carrier concentration for Pt3Bi4S9 (−1.4 × 1019 cm−3) and Pt3Bi4Se9 (−0.898 × 1019 cm−3), calculated n-type zT at 773 K are 0.52 and 0.04, respectively, which are consistent well with the experimental values. Our calculations uncover the upper limit thermoelectric zT of Pt3Bi4X9 and also highlight them as promising thermoelectric materials.
Enhancing high-resolution reconstruction of flow fields using physics-informed diffusion model with probability flow sampling
Authors: Guo Yanan , Cao Xiaoqun , Zhou Mengge , Leng Hongze , Song Junqiang
Published: November 2024

The application of artificial intelligence (AI) technology in fluid dynamics is becoming increasingly prevalent, particularly in accelerating the solution of partial differential equations and predicting complex flow fields. Researchers have extensively explored deep learning algorithms for flow field super-resolution reconstruction. However, purely data-driven deep learning models in this domain face numerous challenges. These include susceptibility to variations in data distribution during model training and a lack of physical and mathematical interpretability in the predictions. These issues significantly impact the effectiveness of the models in practical applications, especially when input data exhibit irregular distributions and noise. In recent years, the rapid development of generative artificial intelligence and physics-informed deep learning algorithms has created significant opportunities for complex physical simulations. This paper proposes a novel approach that combines diffusion models with physical constraint information. By integrating physical equation constraints into the training process of diffusion models, this method achieves high-fidelity flow field reconstruction from low-resolution inputs. Thus, it not only leverages the advantages of diffusion models but also enhances the interpretability of the models. Experimental results demonstrate that, compared to traditional methods, our approach excels in generating high-resolution flow fields with enhanced detail and physical consistency. This advancement provides new insights into developing more accurate and generalized flow field reconstruction models.
Inner–outer interaction of unsteady turbulent flow inside duct with wall corrugations: Augmentation and saturation
Authors: Lu Siqi , He Chuangxin , Wang Peng , Liu Yingzheng
Published: November 2024

This study investigates the inner–outer interaction of the unsteady turbulent flow inside a duct with wall corrugations, where “inner” refers to the trapped flow in a corrugation-induced cavity array and “outer” relates to the mainstream flow transporting through a circular duct. Configurations with different pitch–diameter ratios (P/D) are used to demonstrate the effect of the cavity flow pattern on the mainstream flow variations. An improved delayed detached-eddy simulation with dynamic blending function is performed to acquire high-fidelity turbulent flow data, in which dynamic evolution of multi-scale vortex structures containing hairpin vortices and vortex fragments is clearly resolved. The subsequent statistical analysis reveals a nonlinear variation tendency of the inner–outer interaction intensity, experiencing sudden augmentation first and then a gradual attenuation toward the final saturation. Comparatively, a larger pitch ratio results in a stronger interaction under the effect of bicentric recirculation zones within the cavity array. Moreover, a proper orthogonal decomposition analysis allows for the visualization of energetic flow structures, as consistent velocity variations throughout the duct volume are identified for a larger pitch ratio, while discontinuity at the duct termination is found for a smaller pitch ratio. Finally, an advanced elliptical model based on the spatiotemporal cross correlation analysis is proposed to examine the convection velocity and sweeping velocity of the interactive mainstream flow and cavity flow. The results highlighted the presence of first-augmented and then saturated dynamics and kinematics inside the duct with the cavity array.
Antiferromagnetic–ferromagnetic heterostructure-based spin Hall nano-oscillator
Authors: Soni Sandeep , Raj Ravish Kumar , Kaushik Brajesh Kumar
Published: November 2024

Spin oscillators relying on ferromagnetic (FM) materials have been limited to frequency generation in the range of only a few gigahertz. In contrast, antiferromagnetic (AFM) material-based oscillators have a potential for beyond gigahertz range oscillations. However, the use of AFM oscillators is limited due to challenges in detecting and controlling magnetic orientation. This arises from the inherent lack of significant net magnetization in AFMs. This work focuses on exploring the dynamic characteristics of a spin Hall nano-oscillator (SHNO) that addresses these challenges by leveraging the inter-layer exchange interaction between AFM and FM layers. The proposed design demonstrates stable and power-efficient oscillation in the FM layer, relying on the dynamics of the AFM layer. The proposed AFM–FM-based SHNO design achieves a maximum frequency of 16.4 GHz at ISOT = 180 μA. Furthermore, considering the thermal effects at 300 K, the stable oscillation frequency is achieved at 15.94 GHz. The proposed device exhibits robust and tunable oscillations over a wide frequency range with a power consumption of 4 μW. Moreover, this oscillator achieves 3.35× and 2.44× higher oscillation frequency compared to spin torque nano-oscillators and conventional SHNO-based oscillators, respectively.
Impact of electrolyte on the structure and orientation of water at air/water–polyethylene glycol polymer interface
Authors: Bandyopadhyay Anisha , Mondal Jahur Alam
Published: November 2024

Polyethylene glycol (PEG) is a water soluble, non-ionic polymer with applications in drug delivery, protein precipitation, anti-biofouling, water-splitting, Li-ion batteries, and fuel cells. The interaction of PEG with water and electrolytes plays pivotal roles in such applications. Using interface-selective spectroscopy, heterodyne-detected vibrational sum frequency generation, and Raman difference spectroscopy with simultaneous curve fitting analysis, we show that water adopts different structures and orientations at the air/water–PEG interface, which depends on the molar mass of the PEG. At the air/water–PEG4000 (MW 4000u) interface, water is H-up oriented (i.e., water Hs are pointed away from the aqueous bulk) around 3200 cm−1 and H-down oriented (i.e., water Hs are pointed toward the aqueous bulk) around 3470 cm−1. Variation of the bulk concentration of PEG4000 does not change the dual orientation of interfacial water. The presence of an electrolyte (1.0M NaCl) selectively reduces the H-up oriented water without affecting the H-down oriented water at the air/water–PEG4000 interface. The selective reorganization of the interfacial water is assigned to the disruption of the asymmetric hydration around ether-oxygen of the surface-adsorbed PEG4000 by the Na+ ion of the electrolyte. Interestingly, in the case of low molar mass PEG (air/water–PEG200), the interfacial water neither shows the dual orientation nor is affected by 1.0M NaCl.
Numerical investigation on effect of non-parallelism on natural transition in boundary layers around underwater axisymmetric bodies
Authors: Zhao Lei , Liu Di , Kong Chenhao , Lv Junbo , Zhang Yongming , Liu Jianhua
Published: November 2024

For both fluid mechanics and practical engineering problems, it is important to study the effect of non-parallelism on the natural transition in boundary layers around underwater axisymmetric bodies. This paper develops the method of harmonic linearized Navier–Stokes (HLNS) equations for such boundary layers. The method can be used to study the evolution of small disturbances considering the non-parallelism of the basic flow. Based on the results of the HLNS equations, the transition positions of the boundary layers are predicted by the eN method. Because traditional linear stability theory (LST) neglects non-parallelism, the difference between the results using the HLNS method and those given by LST represents the effects of non-parallelism. Numerical calculations are performed for five classical forebody shapes, and the effect of non-parallelism is identified. (i) At each streamwise location, non-parallelism suppresses low-frequency disturbances while promoting high-frequency ones. The influence on high-frequency disturbances is more obvious. (ii) The effect of non-parallelism on the neutral curve focuses on the region near the critical instability position. Non-parallelism slightly delays the critical instability position for most forebody shapes and pushes the unstable zone toward the high-frequency direction while broadening its frequency bandwidth. (iii) The streamwise range at each growth-rate level is widened, implying that non-parallelism destabilizes the boundary layers. (iv) The transition occurs earlier, indicating that non-parallelism promotes the transition. (v) Non-parallelism shifts the dangerous frequency band toward the high-frequency direction. (vi) Non-parallelism enhances the wall pressure fluctuations (WPF) in the unstable laminar zone.
Hydroelastic responses of a multi-modular very large floating structure on a flexible bottom with lateral stress in a two-layer fluid
Authors: Pu J. , Lu D. Q.
Published: November 2024

Based on the small-amplitude water wave theory, an analytical investigation is performed for the interaction between incident waves and a multi-modular very large floating structure (VLFS) in a two-layer fluid with a flexible seabed. A vertical porous flexible plate is fixed in the center of each floating plate to suppress the hydroelastic response. A key innovation is the modeling of both the VLFSs and the seabed as thin elastic plates with the lateral stress. The analytical expressions for dispersion relationships and vertical eigenfunctions are exactly derived in the water regions with a flexible seabed. The series solution of the velocity potential is obtained through the combination of inner product and the least squares approximation method. The study uniquely illustrates the impact of lateral stress and flexible seabeds on wave propagation, revealing that at low frequencies, waves in both open water and plate-covered regions with a flexible seabed exhibit the similar propagation characteristics. At higher frequencies, however, the propagation characteristics of the waves in the open water regions remain unaffected by the presence of a flexible seabed. The lateral stress has significant effects on the roots of dispersion relationships and the hydroelastic responses. The influences of other physical parameters of the fluid and structures are also displayed graphically. The results demonstrate that the increasing number of modules and extending the vertical plates effectively suppress hydroelastic responses and reduce wave transmission. The porous barriers can reduce the stress on the vertical plates and weaken the effect of barriers for suppressing hydroelastic response.
Experimental study on acoustic and flame responses in an annular combustor under azimuthal force
Authors: Wu Han , Fang Yuanqi , Ma Chengbiao , Wang Gaofeng
Published: November 2024

This study investigates the flame dynamics of an annular combustor under various azimuthal acoustic forces. The experimental platform was applied to external azimuthal acoustic force through four loudspeakers installed on the wall outside the plenum. Experiments were conducted with an equivalence ratio of Ф = 0.71 and a combustion power of P = 9.5 kW. Therein, four loudspeakers were used to precisely control the acoustic pressure amplitude, spinning ratio, and spinning direction, which stimulated the first-order standing mode, spinning modes, and second-order standing mode acoustic mode of the plenum, respectively. Our analysis of flame dynamics and acoustic response characteristics was based on different azimuthal modes, combined with dynamic mode decomposition (DMD) of the flame image sequence and acoustic pressure signal. The results corroborate the consistency between the acoustic field quaternion analysis and the flame image sequence DMD results despite varied external forcing conditions. Specifically, the characteristics of the flame vary by the applied forces. Moreover, DMD results indicate that the flame structure of the eigenfrequency mode is asymmetrical in spinning modes and tilts in the direction of the pressure gradient.
Advancing DFT predictions in Cu-chalcogenides with full-yet-shallow 3d-orbitals: Meta-GGA plus Hubbard-like U correction
Authors: Zhang Yubo
Published: November 2024

The technologically important Cu-chalcogenides, such as Cu2Se and CuInSe2, usually have relatively small band gaps. Achieving a reliable yet efficient description of the electronic properties has proven to be quite challenging for the popular exchange-correlation functionals of density functional theory, primarily due to the involvement of full-yet-shallow Cu-3d orbitals. In this study, we evaluate the applicability of several meta-generalized gradient approximation (GGA) functionals that have been recently developed. We find that the r2SCAN (regularized-restored strongly constrained and appropriately normed) functional significantly improves upon conventional local density approximation and GGA in terms of geometry and electronic band structure; however, there is still a notable discrepancy with experimental results due to the remaining delocalization error. This error is mitigated by combining r2SCAN with a Hubbard-like U correction applied to the Cu-3d orbitals. For predicting band gaps, both the TASK functional and the mBJ potential, when combined with the U correction, demonstrate similar accuracies with a mean absolute error of 0.17–0.19 eV. This accuracy is lower than that achieved with the many-body Hedin’s GW approximation method but more accurate than that of hybrid functionals. Moreover, the r2SCAN+U approach well reproduces the phonon dispersion in CuInSe2, revealing a neglected computational problem in previous reports. We conclude that the meta-GGA+U approach represents a significant advancement by striking a balance between reliability and computational effort, and further efforts are still required to describe the Cu-3d orbitals more accurately.
An experimental and numerical study on the behavior of finite-length column vortex
Authors: Das Swetarka , Yadav Dharmendra , Gupta Abhisek Kumar , Das Debopam , De Ashoke
Published: November 2024

This paper explores experimental and numerical investigation of the spatiotemporal dynamics of a finite-length vortex column in three dimensions using particle image velocimetry and large eddy simulation. The research examines the combined impact of bending, buckling, and core-splitting on a finite-length vortex column. More precisely, the work centers on the fundamental motions, evolutions in flow along the axis, how the shape of the vortex core changes over time, the instability caused by the long waves on the vortex column, and the division of the vortex core. A novel prototype is developed that utilizes piston-driven inflow and produces a vortex column through the principles of flow separation and Biot–Savart induction, which is studied for predicting an ex situ cyclonic line vortex. The present study discusses the complete three-dimensional overview of the same columnar vortex. The meridional swirl and the axial transport of vorticity deform the shape of the core cross sections in different lengths of the column. The jump in the axial velocity at the core boundary allows for the occurrence of bending instabilities with a left-handed helical structure. These instabilities have a long wavelength, similar to the length of the vortex column, and belong to the m = +1 mode. The vortex column experiences a non-uniform curvature and torsion caused by the intricate shape of the laboratory model and varying flow speeds at different heights of the vortex column. The results offer valuable insights into the role of inertia, Coriolis, and viscous forces on the dynamics of the vortex column.
Thermo-economic performance analysis and multi-objective optimization of viscosity ratio and thermal conductivity ratio of copper oxide–palm oil nanolubricants
Authors: Sofiah A. G. N. , Pasupuleti J. , Samykano M. , Rajamony Reji Kumar , Pandey A. K. , Sulaiman Nur Fatin
Published: November 2024

Through experimental research, this work explores the thermophysical properties, cooling efficiency, and economic viability of copper oxide–palm oil nanolubricants in tribology applications. The viscosity and thermal conductivity of the nanolubricants were tested at three different volume concentrations (0.1, 0.3, and 0.5 vol. %) throughout a temperature range of 30 °C to 80 °C at intervals of 10 °C. Researchers looked attentively at how the viscosity and thermal conductivity ratios of the nanolubricants were affected by temperature and volume concentration. A significant increase in thermal conductivity was noted with increasing concentration and temperature. On the other hand, as temperature increased, viscosity reduced and was dependent on volume concentration. The property enhancement ratio was used to evaluate the nanolubricants' cooling capacity before an economic analysis of their cooling efficacy was conducted. Based on experimental data, the study led to the creation of novel correlations between the viscosity ratio and thermal conductivity ratio. These models showed a high degree of agreement (R2 values of 99.47% for the thermal conductivity ratio and 97.78% for the viscosity ratio) between the expected and actual outcomes. The ideal values of the viscosity and thermal conductivity ratios were 1.10 and 1.62, respectively. These values corresponded to a critical temperature of 37.32 °C and a volume concentration of 0.16 vol. % for nanoadditives. The findings offer valuable insights into optimizing nanolubricants for enhanced cooling performance in tribological systems, with potential applications in improving energy efficiency and reducing operational costs in industrial processes.
Run-and-tumble particles in slit geometry as a splitting probability problem
Authors: Frydel Derek
Published: November 2024

Run-and-tumble particles confined between two walls seem like a simple enough problem to possess analytical tractability. Yet, to date no satisfactory analysis is available for dimensions higher than one. This work contributes to the theoretical understanding of this system by reinterpreting it as a splitting probability problem. Such reinterpretation permits us to formulate the problem as the integral equation, rather than a more standard formulation based on the Fokker–Planck equation. In addition to providing an analogy with another phenomenon, the reinterpretation permits a new type of analysis, yields useful results, and offers some analytical tractability.
Converging acoustic waves through complex media with a four-phase metalens
Authors: Yao Jie , Sun Shi-Zhuo , Lv Yu-Hang
Published: November 2024

Wavefront shaping is an established solution to converge acoustic waves through complex media. Discrete phase sampling is inevitable in practice because of manufacture resolution. Limited phase sampling undermines focusing performance, which is hardly improved by increasing the number of phase sections. We propose that such loss can be alleviated when the modulator is designed directly on discrete phases. The feedback-based wavefront shaping with the genetic algorithm has been taken here. The performance of the optimized four-phase metalens catches up with the continuous one and is robust to variations in complex media. Experiments have confirmed its function. These results have potential applications in acoustic focusing and imaging through complex media.
Control of probability flow in Markov chain Monte Carlo—Nonreversibility and lifting
Authors: Suwa Hidemaro , Todo Synge
Published: November 2024

The Markov chain Monte Carlo (MCMC) method is widely used in various fields as a powerful numerical integration technique for systems with many degrees of freedom. In MCMC methods, probabilistic state transitions can be considered as a random walk in state space, and random walks allow for sampling from complex distributions. However, paradoxically, it is necessary to carefully suppress the randomness of the random walk to improve computational efficiency. By breaking detailed balance, we can create a probability flow in the state space and perform more efficient sampling along this flow. Motivated by this idea, practical and efficient nonreversible MCMC methods have been developed over the past ten years. In particular, the lifting technique, which introduces probability flows in an extended state space, has been applied to various systems and has proven more efficient than conventional reversible updates. We review and discuss several practical approaches to implementing nonreversible MCMC methods, including the shift method in the cumulative distribution and the directed-worm algorithm.
Analysis of forces on nodules during Coandă-effect-based hydraulic collection
Authors: Liu Zihan , Zhao Guocheng , Xiao Longfei
Published: November 2024

The nodule pickup device is a crucial component of a deep-sea mining system. It is widely perceived that leveraging water flow for the separation and retrieval of nodules is a promising approach. A series of experiments and numerical simulations were conducted to examine the impact of non-dimensional parameters on the force characteristics and flow field of the particle in Coandă-effect-based hydraulic collection. The results showed that the lift coefficient of the particle initially increased before subsequently diminishing from the jet nozzle to the rear. Notably, the lift coefficient α reached its maximum at the convex curved surface between x/d = −0.17 and 0.33. Furthermore, a distinct linear correlation was established between the maximum lift coefficient αmax and Froude number Fr across varying h/d, and an empirical formula for predicting the lift coefficient was developed through data fitting. Upon experimental validation, the prediction exhibited a maximum error of less than 20%. Additionally, numerical simulations revealed that the particle significantly influenced the flow dynamics within the collection area, and the flow field characteristics and the particle forces can be corroborated with each other. The findings not only provided a reliable quantitative tool for assessing the particle force but also facilitated precise predictions of collection performance, aiding in the selection of optimal operational parameters in deep-sea hydraulic collection.
Fiber motion in rotor spinning unit airflow: Numerical simulation and experimental validation
Authors: Shi Qianqian , Li Ling , Du Shiyi , Zhang Yuze , Ding Qian , Wang Jiang , Wang Jun
Published: November 2024

Airflow-assisted manufacturing holds significant promise across various applications, including rotor spinning, where airflow is crucial for fiber transfer and ultimately affects yarn performance. This study introduces a three-dimensional model of flexible fiber motion within the flow field of a rotor spinning unit. The fiber is modeled as cylindrical segments connected by rigid joints, with the segments experiencing fluid torques and the joints subjected to fluid forces. The model accounts for the fiber bending and torsional deformation. Fiber motion is determined by solving the translational and rotational equations, alongside the fiber–wall interactions. Emphasis is placed on the fiber stripping process from the opening roller. Supported by the numerical methods validated through visualization experiments and further corroborated by spinning examinations, we advance the understanding of the motion behavior of fibers released from different initial positions in the rotor spinning unit, and specifically, delve into the impact of airflow patterns on fiber movement. The developed numerical methodology and findings are vital for optimizing rotor spinning unit design and effectively harnessing airflow technology in processing.
A new optimization strategy, the influence of hollow electrode chamfers on the development of helium atmospheric pressure plasma jets
Authors: Wang Jialei , Chen Kai , Yao Chenguo , Wu Feiyu , Liang Runze , Chen Yue , Dong Shoulong
Published: November 2024

This work suggests applying chamfering treatment to the plasma generator of the empty electrode structure. Enhancing the electrodes’ physical structure can significantly improve plasma characteristics without requiring intricate control systems. Experiments have shown that changes in the electrode’s shape can lead to changes in the formation of the atmospheric pressure plasma jet. Specifically, our observations indicate that an increase in the chamfer radius leads to an increase in the ignition voltage and a greater density of reactive species inside the jet. We developed a multi-channel equivalent circuit model to describe the discharge process of a plasma jet. Then, using the mixed layer theory, we investigated the effect of the chamfer radius on the plasma jet. Our findings suggest that chamfering increases the effective discharge area, resulting in more discharge channels in the model. This leads to a higher density of reactive species. Additionally, chamfering improves the mixing of helium and air, increasing the concentration of N2 and O2. This consumes some of the avalanche electrons and raises the ignition voltages, ultimately enhancing the chemical reactivity of the plasma jet. This work provides new ideas for the optimization strategy of atmospheric pressure plasma radiation devices.
Vieta–Lucas polynomials-based collocation simulation to analyze the solvent fraction factor in active and passive control flow induced by torsional motion
Authors: Kumar Ravikumar Shashikala Varun , Kumar Rangaswamy Naveen , Raghunandan Mavinakere Eshwaraiah , Prasannakumara Ballajja Chandrappa
Published: November 2024

The present research explores the Boger fluid flow past a stretching cylinder with torsional motion in the presence of the magnetic field. It is assumed that the cylinder rotates continuously around its axis and that the starting point's position along the axis correlates with the cylinder wall's expansion rate. Additionally, the consequence of active and passive control of nanoparticles, activation energy, thermophoresis, and Brownian motion effects are considered. Similarity variables transform the governing partial differential equations into non-dimensional ordinary differential equations (ODEs). Furthermore, the Vieta–Lucas polynomials-based collocation method (V-LPBCM) is employed to solve the resulting ODEs. The V-LPBCM outcomes of Nusselt and Sherwood numbers are compared with Runge–Kutta Fehlberg's fourth-fifth-order scheme for validation purposes. The impact of various dimensionless parameters on the different profiles is depicted in the graphical representation. The increase in values of the magnetic parameter, the ratio of relaxation time, and the Reynolds number decline the velocity profile. The velocity profile increases as the values of the solvent fraction parameter rise. The thermal profile increases as the heat source/sink, and thermophoretic parameters rise. The increase in values of activation energy parameter increases the thermal profile.
The impact of quantum-sized nickel nanoparticles on TiO2 in photovoltaic and photocatalytic systems
Authors: Paul Alphonsa , Joseph Nisha , Sebastian Tina , C. O. Sreekala , R. G. Bindu , Augustine Saji
Published: November 2024

The study examines the impact of the incorporation of quantum-sized nickel (Ni) nanoparticles in TiO2 (titanium dioxide) matrix at 1%, 3%, and 5% weight percentages by straightforward, easy, and potentially effective synthesis strategy of direct doping. The structural, morphological, optical, and electrical characterization studies of synthesized films are systematically done and the photovoltaic, photocatalytic applications are evaluated. The integration of nickel into TiO2 influences its photovoltaic properties by enhancing the open-circuit voltage (Voc). However, higher concentrations lead to increased recombination and defects, decreasing efficiency. On conducting photocatalytic studies, TiO2 doped with 1 wt. % nickel exhibits superior photocatalytic efficiency, surpassing that of undoped TiO2. This improvement in photovoltaic and photocatalytic performance is attributed to better charge separation and reduced recombination. However, optimizing nickel levels is crucial for maximizing benefits for the applications using the performed synthesis strategy.
Time-resolved heterodyne-detected electronic sum frequency generation (TR-HD-ESFG) spectroscopy: A new approach to explore interfacial dynamics
Authors: Roy Subhadip , Ahmed Mohammed , Nihonyanagi Satoshi , Tahara Tahei
Published: November 2024

Aqueous interfaces containing organic/inorganic molecules are important in various biological, industrial, and atmospheric processes. So far, the study on the dynamics of interfacial molecules has been carried out with time-resolved vibrational sum-frequency generation (TR-VSFG) and time-resolved electronic sum-frequency generation (TR-ESFG) techniques. Although the ESFG probe is powerful for investigating interfacial photochemical dynamics of solute molecules by monitoring the electronic transition of transients or photoproducts at the interface, heterodyne detection is highly desirable for obtaining straightforward information, particularly in time-resolved measurements. So far, heterodyne detection has been realized only for TR-VSFG measurements but not for TR-ESFG measurements. In this paper, we report on femtosecond time-resolved heterodyne-detected ESFG (TR-HD-ESFG) spectroscopy for the first time. With TR-HD-ESFG developed, we measured the time-resolved electronic ΔImχ(2) spectra (pump-induced changes in the imaginary part of the second-order susceptibility) of a prototype dye, malachite green (MG), at the air/water interface. The obtained ΔImχ(2) spectra clearly show not only the ground-state bleach but also the excited-state band of MG at the air/water interface, demonstrating the high potential of TR-HD-ESFG as a new powerful tool to investigate ultrafast reaction dynamics at the interface.
Research on the viscosity characteristics of water glycol hydraulic fluids in deep-sea environment from molecular dynamics
Authors: Liu Liwei , Xiao Dingcheng , Wang Zhenyao , Deng Yipan , Liu Yinshui
Published: November 2024

The utilization of water glycol as a working medium represents a significant advancement in the realm of deep-sea hydraulic transmission systems. The viscosity of water glycol is a crucial parameter for hydrodynamic lubrication, yet it is profoundly influenced by the environmental conditions of the deep sea. This study employs the TIP4P/2005 water molecule model in conjunction with the optimized potentials for liquid simulations all-atom force field, and non-equilibrium molecular dynamics method to predict the viscosity of water glycol hydraulic fluids with varying compositions under deep-sea conditions. The simulation values agree well with the experimental results. Furthermore, this study introduces a fitting equation that accounts for the effects of composition, temperature, and pressure, enabling the prediction of the viscosity of water glycol hydraulic fluids within the 0–11 000 m sea water environment.
Numerical investigation on the liquid jet and the dynamics of the near-wall cavitation bubble under an acoustic field
Authors: Du Xianrong , Yin Jianyong , Zhang Yongxue , Tian Lei , Li Huayang , Chen Yu
Published: November 2024

The dynamics of the near-wall cavitation bubble in an acoustic field are the fundamental forms of acoustic cavitation, which has been associated with promising applications in ultrasonic cleaning, chemical engineering, and food processing. However, the potential physical mechanisms for acoustic cavitation-induced surface cleaning have not been fully elucidated. The dynamics of an ultrasonically driven near-wall cavitation bubble are numerically investigated by employing a compressible two-phase model implemented in OpenFOAM. The corresponding validation of the current model containing the acoustic field was performed by comparison with experimental and state-of-the-art theoretical results. Compared to the state without the acoustic field, the acoustic field can enhance the near-wall bubble collapse due to its stretching effect, causing higher jet velocities and shorter collapse intervals. The jet velocity in the acoustic field increases by 80.2%, and the collapse time reduces by 40.9% compared to those without an acoustic field for γ = 1.1. In addition, the effects of the stand-off distances (γ), acoustic pressure wave frequency (f), and initial pressure (p*) on the bubble dynamic behaviors were analyzed in depth. The results indicate that cavitation effects (e.g., pressure loads at the wall center and the maximal bubble temperature) are weakened with the increase in the frequency (f) owing to the shorter oscillation periods. Furthermore, the maximum radius of bubble expansion and the collapse time decrease with increasing f and increase with increasing p*. The bubble maximum radius reduces by 12.6% when f increases by 62.5% and increases by 20.5% when p* increases by 74%.
The effects of ventilation layout on cough droplet dynamics relating to seasonal influenza
Authors: Norvihoho Leslie Kojo , Yin Jing , Zhu Xin-Gang , Xue Shu-Qin , Yu Hai-Tao , Zhou Zhi-Fu
Published: November 2024

The primary aim of this paper is to investigate airborne virus transmission in a typical meeting room relating to the heating, ventilation, and air conditioning (A.C.) systems. While the installation of 4-way cassette A.C. systems in offices and meeting rooms has become increasingly common, their efficiency in mitigating short-range airborne virus spread remains poorly understood. Addressing this gap is critical in the post-pandemic era, where understanding the limitations of various ventilation systems is paramount for public health. We systematically compare the performance of the 4-way cassette A.C., various configurations of mixing and displacement ventilation systems, and natural ventilation in controlling the spread of respiratory viruses. Our research uniquely integrates evaporation models to accurately simulate cough clouds' multiphase behavior under both quiescent and thermally influenced conditions. The study benchmarks these systems against two widely recognized ventilation standards (i.e., 5 air changes per hour and 10 l/s per person), offering evidence-based insights applicable across diverse indoor settings. Our findings reveal significant thermal effects in the quiescent case, resulting in 32.3%, 54.3%, and 8.0% changes in the axial, vertical, and lateral spread of the virus-laden droplets, respectively. Notably, the 0.5 m/s 4-way cassette A.C. system demonstrated superior performance, reducing the axial spread by 29.6% compared to other mechanical ventilation configurations. Furthermore, the role of exhaust outlets or doors was found to be critical in shaping the spread pattern in natural ventilation scenarios. This work can offer practical guidance to office workers, engineers, and public health officials on enhancing indoor airborne infection control.
Sensitive direct converting thin film x-ray detector utilizing β-Ga2O3 fabricated via MOCVD
Authors: Gan Zhiyu , Li Chen , Hou Xiaohu , Yu Shunjie , Bai Shiyu , Peng Zhixin , Han Keju , Zou Yanni , Wang Zhiwei , Zhao Xiaolong , Xu Guangwei , Long Shibing
Published: November 2024

Ga2O3 has been considered as one of the most suitable materials for x-ray detection, but its x-ray detection performance is still at a low level due to the limitation of its quality and absorbance, especially for hard x-ray. In this work, the effects of growth temperature and miscut angle of the sapphire substrate on the crystal quality of Ga2O3 thin films were investigated based on the MOCVD technique. It was found that the crystal growth mode was transformed from island growth to step-flow growth using miscut sapphire substrates and increasing growth temperature, which was accompanied by the improvement of the crystal quality and the reduction of the density of trapped states. Ga2O3 films with optimal crystal quality were finally prepared on a 4° miscut substrate at 900 °C. The x-ray detector based on this film shows good hard x-ray response with a sensitivity of 3.72 × 105μC·Gyair−1·cm−2. Furthermore, the impacts of Ga2O3 film crystal quality and trap density on the x-ray detector were investigated in depth, and the mechanism of the photoconductive gain of the Ga2O3 thin-film x-ray detector was analyzed.
A high-order physical-constraints-preserving arbitrary Lagrangian–Eulerian discontinuous Galerkin scheme for one-dimensional compressible multi-material flows
Authors: Zhao Xiaolong , Yu Xijun , Qing Fang , Zou Shijun
Published: November 2024

In this paper, a high-order physical-constraints-preserving arbitrary Lagrangian–Eulerian (ALE) discontinuous Galerkin scheme is proposed for one-dimensional compressible multi-material flows. Our scheme couples a conservative equation related to the volume-fraction model with the Euler equations for describing the dynamics of fluid mixture. The mesh velocity in the ALE framework is obtained by using an adaptive mesh method that can automatically concentrate the mesh nodes near the regions with large gradient values and greatly reduce the numerical dissipation near material interfaces. Using this adaptive mesh, the resolution of solution near some special regions such as material interfaces can be improved effectively by our scheme. With the appropriate time step condition and using a bound-preserving and positivity-preserving limiter, our scheme can ensure the positivity of density and pressure and the boundness of volume-fraction, which further ensures the computational robustness and degree of confidence of simulations under large density or pressure ratios and so on. In general, our scheme can be applied to the simulations of compressible multi-material flows efficiently with the essentially non-oscillatory property and physical-constraints-preserving (bound-preserving and positivity-preserving) property, and its steps are more concise compared to some other methods such as the indirect ALE methods. Some examples are tested to demonstrate the accuracy, essentially non-oscillatory property and physical-constraints-preserving property of our scheme.
Evaluation and optimization of interventional blood pump based on hydraulic performances and hemocompatibility performances
Authors: Li Yuan , Zhang Mengqi , Sun Anqiang , Wang Xiaofei , Fan Yubo , Chen Zengsheng
Published: November 2024

This study was designed to investigate the effects of hemodynamic environment and design factors on the hydraulic performance and hemocompatibility of interventional blood pumps using computational fluid dynamics methods combined with specialized mathematical models. These analyses assessed how different hemodynamic environments (such as support mode and artery size) and blood pump configurations (including entrance/exit blade angles, rotor diameter, blade number, and diffuser presence) affect hydraulic performance indicators (rotational speed, flow rate, pressure head, and efficiency) and hemocompatibility indicators (bleeding, hemolysis, and thrombosis). Our findings indicate that higher perfused flow rates necessitate greater rotational speeds, which, in turn, reduce both efficiency and hemocompatibility. As the artery size increases, the hydraulic performance of the pump improves but at the cost of worsening hemocompatibility. Among the design parameters, optimal configurations exist that balance both hydraulic performance and hemocompatibility. Notably, a configuration without a diffuser demonstrated better hydraulic performance and hemocompatibility compared to one with a diffuser. Further analysis revealed that flow losses primarily contribute to the degradation of hydraulic performance and deterioration of hemocompatibility. Shear stress was identified as the major cause of blood damage in interventional blood pumps, with residence time having a limited impact. This study comprehensively explored the effects of operating environment and design parameters on catheter pump performance using a multi-faceted blood damage model, providing insights into related complications from a biomechanical perspective. These findings offer valuable guidance for engineering design and clinical treatment.
Selective 8-oxo-rG stalling occurs in the catalytic core of polynucleotide phosphorylase (PNPase) during degradation
Authors: Miller Lucas G. , Kim Wantae , Schowe Shawn , Taylor Kathleen , Han Runhua , Jain Vashita , Park Raeyeon , Sherman Mark , Fang Janssen , Ramirez Haydee , Ellington Andrew , Tamamis Phanourios , Resendiz Marino J. E. , Zhang Y. Jessie , Contreras Lydia
Published: November 2024

RNA oxidation, predominantly through the accumulation of 8-oxo-7,8-dihydroguanosine (8-oxo-rG), represents an important biomarker for cellular oxidative stress. Polynucleotide phosphorylase (PNPase) is a 3′-5′ exoribonuclease that has been shown to preferentially recognize 8-oxo-rG-containing RNA and protectEscherichiacolicells from oxidative stress. However, the impact of 8-oxo-rG on PNPase-mediated RNA degradation has not been studied. Here, we show that the presence of 8-oxo-rG in RNA leads to catalytic stalling ofE. coliPNPase through in vitro RNA degradation experiments and electrophoretic analysis. We also link this stalling to the active site of the enzyme through resolution of single-particle cryo-EM structures for PNPase in complex with singly or doubly oxidized RNA oligonucleotides. Following identification of Arg399 as a key residue in recognition of both single and sequential 8-oxo-rG nucleotides, we perform follow-up in vitro analysis to confirm the importance of this residue in 8-oxo-rG-specific PNPase stalling. Finally, we investigate the effects of mutations to active site residues implicated in 8-oxo-rG binding throughE. colicell growth experiments under H2O2-induced oxidative stress. Specifically, Arg399 mutations show significant effects on cell growth under oxidative stress. Overall, we demonstrate that 8-oxo-rG-specific stalling of PNPase is relevant to bacterial survival under oxidative stress and speculate that this enzyme might associate with other cellular factors to mediate this stress.
Forecasting Africa’s fertility decline by female education groups
Authors: Adhikari Saroja , Lutz Wolfgang , Kebede Endale
Published: November 2024

While female education has long been recognized as a key driver of fertility decline during the process of demographic transition and most population projection models consider it implicitly or explicitly in their forecasts of overall fertility, there still is need for a method to forecast education-specific fertility trends directly. Here we propose a method for projecting education-specific fertility declines for cohorts of women in Sub-Saharan Africa based on all available demographic and health surveys data for African countries (including 1.03Mio cases). We study at different levels of aggregation (sample clusters, strata, and national) the associations between ideal family size and completed cohort fertility for education groups, on the one hand, and the average level of education in those units, on the other. The consistently very strong empirical associations suggest a plausible narrative by which a higher prevalence of educated women in a spatial unit influences the fertility levels of women in all specific education categories. Empirical associations between education-specific cohort fertility trends at the national level and newly available quality-adjusted human capital data for these cohorts are then operationalized to produce education-specific population projections as they are needed for—among other uses—the shared socioeconomic pathways scenarios that are widely used in the climate change research community. Sensitivity analyses including out-of-sample projections support the validity of the proposed method which is then applied to 37 African countries.
Unveiling the cell biology of hippocampal neurons with dendritic axon origin
Authors: Han Yuhao , Hacker Daniela , Donders Bronte Catharina , Parperis Christopher , Thuenauer Roland , Leterrier Christophe , Grünewald Kay , Mikhaylova Marina
Published: November 2024

In mammalian axon-carrying–dendrite (AcD) neurons, the axon emanates from a basal dendrite, instead of the soma, to create a privileged route for action potential generation at the axon initial segment (AIS). However, it is unclear how such unusual morphology is established and whether the structure and function of the AIS in AcD neurons are preserved. By using dissociated hippocampal cultures as a model, we show that the development of AcD morphology can occur prior to synaptogenesis and independently of the in vivo environment. A single precursor neurite first gives rise to the axon and then to the AcD. The AIS possesses a similar cytoskeletal architecture as the soma-derived AIS and similarly functions as a trafficking barrier to retain axon-specific molecular composition. However, it does not undergo homeostatic plasticity, contains lesser cisternal organelles, and receives fewer inhibitory inputs. Our findings reveal insights into AcD neuron biology and underscore AIS structural differences based on axon onset.