bluuebunny/crossref_metadata_2025 huggingface dataset:
Plasmonic hybridization modes in VO2@Au nanoshell: A comprehensive review and theoretical analysis
Authors: Amjadi Neda , Hatef Ali
Published: July 2024

Phase change materials (PCMs) have received significant attention in various fields due to their remarkable ability to undergo phase transitions and induce substantial changes in their physical properties. One such material, vanadium dioxide (VO2), has emerged as a prominent PCM that exhibits a reversible metal–insulator transition near room temperature. These transitions are accompanied by rapid modifications in electrical conductivity and surface properties. Efforts have been made recently to enhance the performance and expand the utility of VO2 by combining it with other materials and structures. One effective approach is the use of plasmonic hybridization with vanadium dioxide (VO2), which enhances the optical and functional properties of VO2-based materials. This study offers a comprehensive review of previous research, with a specific focus on investigating the plasmonic hybridization in VO2@Au nanoshells. To analyze the plasmonic modes in this innovative core–shell structure, a combined theoretical and simulation-based approach is employed. The investigation encompasses both the semiconductor and metallic phases of the VO2 core, revealing the presence of sphere and cavity plasmonic modes. Remarkably, the results highlight that the cavity frequency becomes the dominant mode beyond wavelengths of 778 nm, particularly in the metallic phase. Furthermore, this study presents valuable insights into the charge distribution resulting from symmetric and asymmetric plasmon oscillations at specific wavelengths, particularly in the optimized scenario of the VO2@Au nanoshell.
Comprehensive insights on mechanical properties of natural–synthetic fibers with MWCNT nano-composite
Authors: Arunachalam S. Jothi , Saravanan R. , Sathish T. , Giri Jayant , Fatehmulla Amanullah
Published: July 2024

The purpose of this study was to see how silane treatment affected the tensile and impact strength of composites constructed from jute/kenaf/glass fibers with a nano-graphene filler and to investigate the impact of major treatment factors, such as silane concentration, immersion duration, and nano-filler, on composite characteristics. To conduct systematic trials and improve these variables, the Response Surface Methodology (RSM) with central composite designs was used. To precisely forecast the tensile and impact strength of the nano-composite following silane treatment, quadratic models were built. By changing the silane concentration, immersion period, and nano-filler, they discovered ideal conditions for increasing tensile strength. The best ranges for silane concentration and immersion duration were discovered to be 15 wt. % and 30 min, respectively. Given the conditions, the composite impact strength increased by 51% and its tensile strength improved by 22% as compared to the values achieved from RSM optimization. These results highlight the practical importance of silane treatment, especially in improving tensile and impact strength and strengthening the interfacial adhesive characteristics of organic fibers and polymer matrices.
Dynamics of a wall-mounted flexible plate in oscillatory flows
Authors: Zhang Jian-tao , Nakamura Takashi
Published: July 2024

The present work numerically studies the dynamics of a two-dimensional wall-mounted flexible plate in an oscillatory flow, aiming to assess the effect of structure bending stiffness and wave orbital excursion on the plate deflection, reconfiguration, and drag reduction. Different modes of dynamic responding behaviors are identified such as quasi-linear, linear, non-linear, and irregular modes with varied studying parameters. The plates of the quasi-linear mode show a fully reconfigured state in oscillatory flow with different wave excursions, of which the tip deflection and effective length for the reconfiguration effect are analyzed and the scaling laws are derived based on force and energy balances. With decreasing elasticity, the plates through linear motion show the limitation of reconfiguration and move passively and rigorously following along oscillatory flow with zero phase lag, wherein the tip deflections saturate to the same order as wave excursions and the effective lengths change slightly where the bending stiffness effect is insignificant. A critical Cauchy number, Cacri, which separates the fully reconfigured state and passive movement state, is proposed using the scaling arguments based on the time scales of flow oscillation frequency and time for plates to reach full reconfiguration for different wave orbital excursions. To account for the non-linear motion effect on drag reduction, we derive a scaling model based on the spatially and temporally averaged relative velocity and the prediction performs well. Furthermore, a rich phenomenology of fluid–structure interaction including phase lag, fluid loading distribution, internal elastic energy, vibration resonance, and vortex structure is presented.
Extending the Tavis–Cummings model for molecular ensembles—Exploring the effects of dipole self-energies and static dipole moments
Authors: Borges Lucas , Schnappinger Thomas , Kowalewski Markus
Published: July 2024

Strong coupling of organic molecules to the vacuum field of a nanoscale cavity can be used to modify their chemical and physical properties. We extend the Tavis–Cummings model for molecular ensembles and show that the often neglected interaction terms arising from the static dipole moment and the dipole self-energy are essential for a correct description of the light–matter interaction in polaritonic chemistry. On the basis of a full quantum description, we simulate the excited-state dynamics and spectroscopy of MgH+ molecules resonantly coupled to an optical cavity. We show that the inclusion of static dipole moments and the dipole self-energy is necessary to obtain a consistent model. We construct an efficient two-level system approach that reproduces the main features of the real molecular system and may be used to simulate larger molecular ensembles.
Thermoelectric transport properties in Janus Rashba semiconductors of monolayer Si2AsSb and Si2SbBi
Authors: Xia Qiong , Xu Zhiyuan , Zhang Long , Gao Guoying
Published: July 2024

2D Janus Rashba semiconductors, which break both the mirror symmetry in the crystal structure and the spin degeneracy in the energy band, provide a promising platform to optimize thermoelectric performance. Herein, we use first-principles and Boltzmann transport theory to investigate the electron and phonon transport properties for Janus semiconductors of monolayer Si2AsSb and Si2SbBi. The strong Rashba spin-splitting is found in both Janus monolayers especially for Si2SbBi, which decreases the bandgaps and makes the valence bands more dispersive, resulting in decreased p-type Seebeck coefficient and increased p-type electrical conductivity. The lattice thermal conductivities of both monolayers are not low due to the weak phonon anharmonicity, strong chemical bonding, and long phonon relaxation time. The low lattice thermal conductivity of Si2SbBi than Si2AsSb mainly originates from the low phonon group velocity. Both monolayers exhibit better thermoelectric performance in n-type than in p-type. The competition among Seebeck coefficient, electrical conductivity, and electronic thermal conductivity makes the difference of optimal thermoelectric figure of merits in n-type without and with Rashba spin–orbit coupling slight for Si2AsSb, but it is significant for Si2SbBi. Within Rashba spin–orbit coupling, the optimal figure of merits at 700 K reach 0.65 and 0.59 for Si2AsSb and Si2SbBi, respectively, which indicate the potential thermoelectric applications, and will stimulate the broad study on thermoelectric properties of 2D Janus Rashba semiconductors.
Experimental study on a new floating breakwater with openings, arc-shaped wings, and plates
Authors: Wu Shi-Xian , Sun Peng-Nan , Zhou Min-Li , Liu Nian-Nian , Peng Yu-Xiang , Xie Chun-Mei , Ni Xin-Yun
Published: July 2024

Floating breakwaters are crucial for maintaining the safety and performance of marine structures in relatively deep water. At present, conventional floating breakwaters have limited capability of attenuating medium to long-period waves (with periods ranging from 6 to 10 s in this paper). To enhance the performance of attenuating medium to long waves, a new floating breakwater with openings, arc-shaped wings, and plates is proposed in the present paper. Model experiments were carried out to analyze its wave attenuation performance and hydrodynamic characteristics. Comparative tests were also conducted on its prototype with opening passes and wing structures. The experimental results demonstrate that this new floating breakwater exhibits superior performance in attenuating medium to long waves compared to its prototype. However, this improvement comes at the cost of intensifying localized wave slamming and increasing mooring forces to a certain extent.
Analysis of heat generation and transfer in droplet-based acoustofluidic by considering the attenuation effect
Authors: Huang Lei , Zhou Mingyong , Li Luming , Jiang Binyan
Published: July 2024

The droplet-based acoustic microfluidic system has recently demonstrated excellent performance and application potential in biological micro/nanoparticle manipulation, chemical synthesis, and materials science. However, in those applications with obvious temperature response, the heat generation of droplets under the action of surface acoustic waves (SAW) is ignored usually, which highlights the need to analyze the process of SAW heating droplets to guide temperature control. Here, based on the system with relative acoustic field bias arrangement, the influence of SAW attenuation on the distribution of heat sources was studied by constructing a coupled model of heat source heating and fluid heat transfer. The role of SAW attenuation effect on the initial stage of droplet heat generation was analyzed through experiments and simulations, and the mechanism of local heat sources on droplet heat generation was clarified. The temperature field of droplets was determined by the local heat source caused by SAW attenuation and the convective heat transfer generated by the acoustic streaming effect. The correspondence between input power and temperature field was also analyzed, to clarify the scheme for adjusting droplet temperature. This work clarifies the temperature control mechanism of this acoustic systems and enables applications such as biochemical reactions or DNA (deoxyribonucleic acid) amplification.
Optimized collection optic design for divertor Thomson scattering diagnostics in KSTAR
Authors: Park G. H. , Kim H. J. , Lee J. H.
Published: July 2024

Last year, the KSTAR divertor material was changed from carbon to tungsten tiles. An optimized collection optic design for divertor Thomson scattering diagnostics in KSTAR was conducted for electron temperature (1–100 eV) and electron density (1 × 1018–1 × 1019 m−3) profile diagnostics. This diagnostic system will utilize a 1064 nm Nd:YAG laser directly from the K-top port toward the beam dump located at K-bottom, while collecting scattered light from five spatial points in the divertor area via collection optics situated in the j-middle port. Given spatial limitations, the solid angle of measurement points is limited, and the collection optic design facing the tungsten divertor is susceptible to stray light. So, the design of the collection optic is important for divertor Thomson scattering diagnostics. For optimal performance, we performed two types of collection optic designs: Cooke-triplet and double-Gaussian. We present performance ray tracing analysis results for both designs and derive the optimal design.
Mixed quantum–classical modeling of exciton–phonon scattering in solids: Application to optical linewidths of monolayer MoS2
Authors: Krotz Alex , Tempelaar Roel
Published: July 2024

We present a mixed quantum–classical framework for the microscopic and non-Markovian modeling of exciton–phonon scattering in solid-state materials and apply it to calculate the optical linewidths of monolayer MoS2. Within this framework, we combine reciprocal-space mixed quantum–classical dynamics with models for the quasiparticle band structure as well as the electron–hole and carrier–phonon interactions, parametrized against ab initio calculations, although noting that a direct interfacing with ab initio calculations is straightforward in principle. We introduce various parameters for truncating the Brillouin zone to select regions of interest. Variations of these parameters allow us to determine linewidths in the limit of asymptotic material sizes. The obtained asymptotic linewidths are found to agree favorably with experimental measurements across a range of temperatures. As such, our framework establishes itself as a promising route toward unraveling the non-Markovian and microscopic principles governing the nonadiabatic dynamics of solids.
An octahedral Mach B-dot probe for 3D flows and magnetic fields in the edge of reversed field pinches
Authors: Sellner A. M. , von der Linden J. , Himura H. , Reksoatmodjo R. , Sears J. , You S. , Almagri A. F. , McCollam K. J. , Reyfman M. , Rouda C. C. , Sarff J. S.
Published: July 2024

Measurements and simulations show that plasma relaxation processes in the reversed field pinch drive and redistribute both magnetic flux and momentum. To examine this relaxation process, a new 3D Mach B-dot probe has been constructed. This probe collects ion saturation currents through six molybdenum electrodes arranged on the flattened vertices of an octahedron made of boron nitride (BN). The ion saturation current flows through configurable voltage dividers for measurement and returns through one of six selectable return electrodes equally spaced along the 12 cm BN probe arm. In addition, the probe arm houses three B-dot magnetic pickup coils in the BN stalk immediately below to the octahedron, to measure the local magnetic field. Inserted in the Madison Symmetric Torus (MST) during deuterium discharges with 220 kA plasma current, density of 0.8 × 1013 cm−3, the probe collects ion saturation currents with sawtooth-like peaks correlated with relaxation events. This compact octahedral design fitting six Mach electrode surfaces within a 1 cm3 cube will enable future multi-point, multi-field probes compatible with the 1.5 in. ports of MST. Such probes will allow for flow circulation, current, and canonical vorticity to be calculated in the center of the finite difference stencil formed by the measurement locations.
Lopsided elastic dumbbell suspension
Authors: Phan-Thien Nhan , Kanso M. A. , Giacomin A. J.
Published: July 2024

We derive the constitutive equation for a suspension of lopsided Hookean dumbbells. By lopsided, we mean that one bead is larger than the other. We find that all results derived for symmetric Hookean dumbbells can be taken over for lopsided ones by replacing 2/ζ with 1/ζ1+1/ζ2, where ζ and ζ1 and ζ2 are the bead friction coefficients for the symmetric dumbbell beads and for the first and second beads of the lopsided dumbbell, respectively.
Three-dimensional wake dynamics of a twisted cylinder
Authors: Yang Yefei , Li Hui , Jin Xiaowei
Published: July 2024

The flows past a twisted cylinder are studied at low Reynolds numbers using three-dimensional (3D) direct numerical simulations. For comparison, the flows over uniform circular and elliptic cylinders are also investigated. The similar transformations from the two-dimensional (2D) laminar regime to the 3D wake transition regime in the wake of a uniform cylinder are not observed for a twisted cylinder. The wakes of a twisted cylinder inherently display 3D wake patterns owing to the effects of geometrical perturbations. The 3D wakes of the twisted cylinder are still in the stable laminar regime at low Reynolds numbers, leading to continuous variations of various flow quantities with increasing Reynolds numbers. The transformations of the shedding patterns result in discontinuous changes in these flow quantities, such as aerodynamic forces, shedding frequencies, and vortex formation lengths. In addition, some novel characteristics appear in the 3D vortex structures of a twisted cylinder. The spanwise vortex wavelength presents a lock state with the structural wavelength. The shedding vortices are oblique to the cylinder axis in the near wake, and the dislocation occurs among different segments of vortices along the spanwise direction. Moreover, the effects of these vortex features on other flowing quantities are investigated.
Correcting implicit solvation at metal/water interfaces through the incorporation of competitive water adsorption
Authors: Lee Kwanpyung , Schmidt J. R.
Published: July 2024

Conventional continuum solvation models are ubiquitous in computational catalysis, including for describing metal/water interfaces, which are relevant to both solution-phase heterogeneous catalysis and electrocatalysis. Nonetheless, we find that such continuum models qualitatively fail to describe both the adsorption free energy and conformational preference for many organic molecules at such interfaces, largely due to the failure of continuum models to incorporate the role of competitive water adsorption. We develop a simple phenomenological model that accounts for competitive water adsorption and show that the model, when used in conjunction with continuum solvation, provides a dramatic improvement in the description of both adsorption and conformational preference. The model is also extended to additionally incorporate the influence of applied potential at the electrode surface, thus facilitating computationally efficient applications to scenarios including electrocatalysis.
Characterising ignition precursors associated with high levels of deployment of wildland fire personnel
Authors: Cullen Alison C. , Goldgeier Brian R. , Belval Erin , Abatzoglou John T.
Published: July 2024

Background As fire seasons in the Western US intensify and lengthen, fire managers have been grappling with increases in simultaneous, significant incidents that compete for response resources and strain capacity of the current system. Aims To address this challenge, we explore a key research question: what precursors are associated with ignitions that evolve into incidents requiring high levels of response personnel? Methods We develop statistical models linking human, fire weather and fuels related factors with cumulative and peak personnel deployed. Key results Our analysis generates statistically significant models for personnel deployment based on precursors observable at the time and place of ignition. Conclusions We find that significant precursors for fire suppression resource deployment are location, fire weather, canopy cover, Wildland–Urban Interface category, and history of past fire. These results align partially with, but are distinct from, results of earlier research modelling expenditures related to suppression which include precursors such as total burned area which become observable only after an incident. Implications Understanding factors associated with both the natural system and the human system of decision-making that accompany high deployment fires supports holistic risk management given increasing simultaneity of ignitions and competition for resources for both fuel treatment and wildfire response.
Anticipating responses to climate change and planning for resilience in California’s freshwater ecosystems
Authors: Power Mary E. , Chandra Sudeep , Gleick Peter , Dietrich William E.
Published: July 2024

As human-caused climate changes accelerate, California will experience hydrologic and temperature conditions different than any encountered in recorded history. How will these changes affect the state’s freshwater ecosystems? Rivers, lakes, and wetlands are managed as a water resource, but they also support a complex web of life, ranging from bacteria, fungi, and algae to macrophytes, woody plants, invertebrates, fish, amphibians, reptiles, birds, and mammals. In much of the state, native freshwater organisms already struggle to survive massive water diversions and dams, deteriorating water quality, extensive land cover modification for agriculture and urban development, and invasions of exotic species. In the face of climate change, we need to expand efforts to recover degraded ecosystems and to protect the resilience, health, and viability of existing ecosystems. For this, more process-based understanding of river, lake, and wetlands ecosystems is needed to forecast how systems will respond to future climate change and to our interventions. This will require 1) expanding our ability to model mechanistically how freshwater biota and ecosystems respond to environmental change; 2) hypothesis-driven monitoring and field studies; 3) education and training to build research, practitioner, stewardship, and policy capabilities; and 4) developing tools and policies for building resilient ecosystems. A goals-driven, hypothesis-informed collaboration among tribes, state (and federal) agencies, nongovernmental organizations, academicians, and consultants is needed to accomplish these goals and to advance the skills and knowledge of the future workforce of practitioners, regulators, and researchers who must live with the climate changes that are already upon us and will intensify.
A combinatorially complete epistatic fitness landscape in an enzyme active site
Authors: Johnston Kadina E. , Almhjell Patrick J. , Watkins-Dulaney Ella J. , Liu Grace , Porter Nicholas J. , Yang Jason , Arnold Frances H.
Published: July 2024

Protein engineering often targets binding pockets or active sites which are enriched in epistasis—nonadditive interactions between amino acid substitutions—and where the combined effects of multiple single substitutions are difficult to predict. Few existing sequence-fitness datasets capture epistasis at large scale, especially for enzyme catalysis, limiting the development and assessment of model-guided enzyme engineering approaches. We present here a combinatorially complete, 160,000-variant fitness landscape across four residues in the active site of an enzyme. Assaying the native reaction of a thermostable β-subunit of tryptophan synthase (TrpB) in a nonnative environment yielded a landscape characterized by significant epistasis and many local optima. These effects prevent simulated directed evolution approaches from efficiently reaching the global optimum. There is nonetheless wide variability in the effectiveness of different directed evolution approaches, which together provide experimental benchmarks for computational and machine learning workflows. The most-fit TrpB variants contain a substitution that is nearly absent in natural TrpB sequences—a result that conservation-based predictions would not capture. Thus, although fitness prediction using evolutionary data can enrich in more-active variants, these approaches struggle to identify and differentiate among the most-active variants, even for this near-native function. Overall, this work presents a large-scale testing ground for model-guided enzyme engineering and suggests that efficient navigation of epistatic fitness landscapes can be improved by advances in both machine learning and physical modeling.
Effect of laser wavelength on ablation propulsion and plasma characteristics with acrylonitrile butadiene styrene target
Authors: Xu Yongfeng , Yang Liang , Li Jiaqi , Zhou Dongjian , Li Qingwei , Shi Wenbo , Jin Yuqi
Published: July 2024

Propulsion performance produced by laser ablation of polymer made of acrylonitrile butadiene styrene is experimentally investigated using the first, second, and third harmonics of a Nd: YAG laser. A ballistic pendulum is employed to assess the impulse and coupling coefficient for laser propulsion application. Fast photography, target ablation, and optical emission spectroscopy are proposed to analyze the energy coupling characteristic. The impulse and coupling coefficient under different pressures are demonstrated to depend on the target ablation and plasma properties which are relevant to laser wavelength. As the laser wavelength decreases, the crater depth and ablation mass are enhanced. Meanwhile, the plasma plume separates at atmospheric pressure and its length extends continuously in the low-pressure range. As a result, plasma including more ejected particles with higher velocity contributes to obtaining excellent impulse and coupling coefficient. In addition, the decreased electron density and temperature indicate higher collision frequency and photoionization dominate rather than inverse bremsstrahlung absorption at shorter laser wavelengths. This work provides a better understanding of the energy conversion mechanism and a reference for improving propulsion performance.
Arc erosion characteristics of cables with heatproof insulations in AC series circuits at low pressure
Authors: Gao Zishan , Yang Rui , Wang Jian , Tao Zhenxiang , Zhang Jian
Published: July 2024

The droplet diameter, dripping frequency, and arc bead appearances vary significantly with pressure. This study investigated the arc erosion characteristics of copper-core cable with mica insulation (HC0) and aluminum-core cable with PI insulation (HA0) at different pressures. During arcing of HC0, the diameters of dripping droplets decrease as pressure decreases, but the dripping frequency exhibits an increasing trend. The primary arc beads (PABs) of HA0 at atmospheric pressure are mainly globular arc beads. HA0 PABs at 60 kPa are mostly coral arc beads, which is attributed to the slow oxidation rate and easier outflow of liquid aluminum through cracks at low pressure. HA0 PABs have the characteristics of coral arc beads and gradual necking, which broadens the previous theory in accident investigations that coral arc beads and gradual necking are considered as physical evidences of fire globules and short-circuit melted marks. Besides, the influence of pressure on arc duration of HC0 and HA0 is revealed. This study could provide support for fire accident investigation and arc accident prevention.
Superscattering engineering through combined resonant modes
Authors: Wang Yongge , Ye Xin , Yao Jingfeng , Wang Ying , Yuan Chengxun , Zhou Zhongxiang
Published: July 2024

A sub-wavelength particle with a total scattering cross section that exceeds the single channel limit is referred to as a superscatterer, which can provide ability to control light in nanoscale. A variety of superscatter structures have been suggested, most of them are typically constructed with strong forward scattering but minor backscattering. This unusual behavior can be attributed to the superposition of resonant modes in adjacent angular momentum channels. We reveal the mechanism of super backscattering for subwavelength column, which can be formed by recombining non-adjacent resonant modes, as confirmed by our numerical analysis.
Engineering the apparent quantum yield and emission rate of fluorophore molecules by coupling fluorophore dipoles with plasmon modes of gold using low frequency electric fields
Authors: Lakshan K A S , Nawarathna D
Published: July 2024

Localized surface plasmons produced by gold and silver nanostructures have been utilized to enhance the intensity of fluorophore molecules. The issue with using nanostructure plasmons for fluorescence enhancement is their short-range nature (5–50 nm from the nanostructures), which limits accessibility to a few molecules. In addition, fluorophore dipoles needed to be aligned with the plasmon electric fields to maximize the fluorescence enhancement. To address these issues, we used low-frequency electric fields (<5 MHz) and commercially available nanorod and nanosphere samples and studied their effectiveness in enhancing the fluorescence of fluorophore-labeled short single-stranded DNA molecules (22 bases). We demonstrated that DNA molecules and nanorod particles can effectively be manipulated around the charging frequency of DNA molecules (∼3 MHz). Nanorod particles enhanced the fluorescence emission rate by ∼50-fold. When the 3 MHz electric field was introduced, the emission rate increased to over 700-fold. We also found that the introduction of a 3 MHz electric field aided the enhancement of the intrinsic quantum yield fluorophore molecules, which resulted in over a 1000-fold fluorescence enhancement. This enhancement was due to the very high electric produced by polarized DNA dipoles at 3 MHz, which resulted in a torque on fluorophore dipoles and subsequently aligning the fluorophore dipole axis with the plasmon electric field. At a fundamental level, our results demonstrate the role of the low-frequency electric field in the fluorophore–plasmon coupling. These findings can directly be applied to many fluorescence detection systems, including the development of biosensors.
Parametric study of a vortex-enhanced supersonic inductive plasma torch
Authors: Pascale A , Lafleur T , Corr C S
Published: July 2024

The feed gas injection configuration in radio-frequency (RF) inductively coupled plasma (ICP) torches plays a critical role in discharge stability, gas heating, and device thermal management: particularly if a supersonic nozzle is used to subsequently accelerate the hot gas. A novel injection configuration is the bidirectional vortex, which segments the internal ICP flow field into two counter-propagating vortices that can significantly enhance gas heating and reduce heat losses. The diameter of the interface between the vortices (known as the mantle) is expected to be an important dimensional parameter affecting torch operation, especially relative to the nozzle size. In this work, we investigate the effect of nozzle throat diameter on the behaviour and performance of a vortex-enhanced supersonic ICP torch. The system is operated at RF powers and argon mass flow rates between 200–1000 W and 0–400 mg s−1 respectively, and different nozzle diameters ranging from 1.5 to 4 mm are explored. Because of the high-temperature environment, and to prevent disruption of the vortex flow fields, non-invasive diagnostics are used to measure the gas temperature and plasma density, and to infer the torch thermal efficiency and achievable gas specific enthalpy change. The maximum temperature is between 8500–9500 K with the 1.5 mm nozzle giving the highest temperature for a given power and mass flow rate, while plasma densities vary between 1020–1021 m−3 depending on the operating conditions. The thermal efficiency increases from 29% for the 1.5 mm nozzle to just above 70% for the 4 mm nozzle with a similar maximum specific enthalpy of around 1.5 MJ kg−1. These results demonstrate the important coupling between torch properties, and how system optimization can lead to tailored performance of potential interest to several ground and space-based applications.
Comparison of plasma-activated saline prepared with plasma gases with different N2/O2 ratios activated by gliding arc discharge
Authors: Zhao Pengyu , Jia Yikang , Ma Sihong , Zhang Rui , Li Kaiyu , Song Tianyi , Zheng Jianbao , Zhang Jingyao , Guo Li , Liu Dingxin , Wang Xiaohua , Rong Mingzhe
Published: July 2024

Methicillin-resistant Staphylococcus aureus (MRSA) presents a significant threat due to the multiple resistance to antibiotics, leading to severe and challenging-to-treat infections. Plasma-activated saline (PAS) prepared by plasma gases, could efficiently inactivate various pathogenic bacteria including both sensitive and antibiotic-resistant bacteria. In this study, the PAS was prepared by plasma gases with different ratios of N2 and O2 activated by gliding arc discharge. First, the gaseous reactive species in the plasma gases were compared, revealing that the highest levels of NO
x
including NO2 and N2O5 were generated in the gases with the N2/O2 ratios of 4:6, 5:5, and 6:4. Subsequently, the PAS prepared by the two plasma-activated gases at the N2/O2 ratios of 5:5 and 6:4 exhibited the strongest inactivation effects on both planktic MRSA and biofilms. Furthermore, the aqueous reactive species in the PAS exhibited varied change trends with the increasing N2/O2 ratios. Additionally, ultraviolet spectroscopy combined with the probe of N, N-diethyl-p-phenylenediamine was applied for the detection of O2NOO− in the PAS, and the levels of O2NOO− in the PAS were positively correlated with the inactivation effects. Moreover, the PAS induced varying levels of nitration modification on the soluble proteins in MRSA cells, which were related to the intensities of O2NOO− in the PAS. This study regulated the reactive species in the PAS through gas composition and explored the inactivation mechanism of the PAS, providing a new strategy to promote the preparation efficiency of plasma-activated solutions for biomedical applications.
Pulsed corona discharge: an advanced treatment method for antibiotic-contaminated water
Authors: Bilea Florin , Bradu Corina , Medvedovici Andrei V , Hong Dunpin , Magureanu Monica
Published: July 2024

Water pollution is one of the most significant problems of the current century. With the increase in medicine availability and use, pharmaceutical pollutants such as antibiotics become more prevalent in natural environments with potentially negative impact. In this study, a pulsed corona discharge was investigated as a possible treatment method of water contaminated with amoxicillin (AMX). Two system configurations were used: plasma and plasma-ozonation. In order to better grasp the effect of system and water matrix on degradation, different pulse widths, solutions pH and conductivity values, as well as the nature of the dissolved salts were investigated. Decreasing the pulse width from 300 ns to 106 ns (full width at half maximum) led to almost a two-fold increase in energy yield at 50% pollutant removal, and the addition of the ozonation reactor resulted six times enhancement in efficiency. While the water matrix had little impact on AMX degradation, the buffering capacity of carbonates has proven beneficial by preventing pH decrease during treatment. Under optimum conditions, the energy yield was 57 g kWh−1 at 93% removal of AMX in tap water. A number of 26 potential degradation products have been identified, resulting from hydroxylation of the benzene ring, oxidation of the thioester and amine groups, hydrolysis, and cleavage of the benzene, β-lactam and thiazole rings, along with fragmentation of the resulting compounds. All but seven degradation intermediates are completely removed by extending treatment duration to 60 min and the persistent ones are less toxic than the parent compound.
A hybrid multi-measure and improved UMAP approach for train traction motor bearing protection state assessment
Authors: Liu Shuli , Liu Yi , Shen Longjiang , Yang Yin , Shen Yiping , Liu Jingang
Published: July 2024

Different protection states have different protection effects on bogie traction motor bearings under road transportation conditions, which directly affects the stability and safety of later vehicle operations. The motor bearing monitoring system usually adopts the time-frequency domain and other indicators to accurately describe its state, and the selection of specific indicators usually originates from the experience of domain experts. To explore the weak and effective features hidden in the data more deeply, this paper researches feature selection and fusion, and proposes a hybrid multi-measure and improved UMAP approach for train traction motor bearing protection state assessment. Firstly, a platform is built to collect multiple sensor signals of traction motor vibration during road transportation and the time-frequency domain feature set is extracted. Then, by comparing the feature extraction effects of 10 single-measure models, a hybrid multi-measure feature selection model and its evaluation indexes, which comprehensively consider the combined distance measure, correlation, and information measure, are constructed to optimize the best hybrid multimetric and the feature set corresponding to the optimal strategy. To perform multi-sensor feature fusion, the PSO-optimized UMAP algorithm is used for feature fusion of the feature set and compared with eight other algorithms. Finally, the results of feature selection and fusion are input into eight classifiers for performance comparison, and the method achieves more than 85% accuracy in distinguishing different protection states, obviously due to the original feature subset. The experimental results prove the effectiveness of the method proposed in this paper, and it provides a theoretical basis and technical reference for the protection scheme of the traction motor and the design and selection of bearings.
RGBD-based method for segmenting apparent pores within bridge towers
Authors: Zhang Yunan , Chen Bo , Li Yonglong , Wang Haoran , Tan Liguo , Wang Chengyin , Zhang Hua
Published: July 2024

As a crucial technology in computer vision, image semantic segmentation is extensively applied to tasks such as detecting apparent defects in concrete, identifying structural cracks, and interpreting facility scenes within infrastructure settings. Challenges such as uneven lighting inside bridge towers and the similarity in color and texture between concrete pore structures and their surrounding areas frequently result in lower segmentation accuracy. This article introduces a multimodal semantic segmentation model incorporating depth information to tackle these challenges. By integrating depth and RGB images as inputs, the model constructs an interactive space and utilizes a cross-attention mechanism along with global context for guided learning, thus enabling precise feature extraction and segmentation. The experimental results demonstrate that this segmentation network excels on a custom-made concrete pore dataset, with a precision rate of 90.88%, recall rate of 87.48%, intersection over union (IoU) of 80.42%, and F1 and Dice coefficient of 89.10% and 89.15%, respectively. These outcomes affirm the network’s effectiveness in segmenting apparent defects in concrete and offer technical support and solutions for image semantic segmentation tasks in settings like bridge towers.
Nitrogen-rich carbon dots as the antisolvent additive for perovskite-based photovoltaic devices
Authors: Margaryan Igor V , Vedernikova Anna A , Borodina Lyubov’ N , Kuzmenko Natalya K , Koroleva Aleksandra V , Zhizhin Evgeniy V , Zhang Xiaoyu , Ushakova Elena V , Litvin Aleksandr P , Zheng Weitao
Published: July 2024

Solution-processed perovskite solar cells (PSCs) have demonstrated a tremendous growth in power conversion efficiency (PCE). A high-quality, defect-free perovskite-based active layer is a key point to enhance PSC performance. Introduction of additives and interlayers have proved to be an effective tool to passivate surface defects, control crystal growth, and improve PSC stability. Antisolvent engineering has emerged recently as a new approach, which aims to adjust perovskite layer properties and enhance the PCE and stability of PSC devices. Here, we demonstrate that carbon dots (CDs) may serve as a prospective additive for antisolvent engineering. Nitrogen-rich amphiphilic CDs were synthesized from amines by a solvothermal method and used as an additive to chlorobenzene for a perovskite layer fabrication. The interaction between perovskite and functional groups in CDs promotes improved crystallization of an active perovskite layer and defects passivation, bringing higher PSCs efficiency, stability, and suppressed hysteresis. Under optimized CD concentration, the maximum PCE increased by 34% due to the improved short-circuit current and fill factor, and the device maintains 87% of its initial efficiency after 6 d of storage under ambient conditions.
TEM-processed defect densities in single-layer TMDCs and their substrate-dependent signature in PL and Raman spectroscopy
Authors: Moses Badlyan Narine , Quincke Moritz , Kaiser Ute , Maultzsch Janina
Published: July 2024

The optical properties of the direct-bandgap transition metal dichalcogenides (TMDCs) MoS2 and WS2 are heavily influenced by their atomic defect structure and substrate interaction. In this work we use low-voltage chromatic and spherical aberration (CC/CS)-corrected high-resolution transmission electron microscopy to simultaneously create and image chalcogen vacancies in TMDCs. However, correlating the defect structure, produced and analyzed using transmission electron microscopy (TEM), with optical spectroscopy often presents challenges because of very different fields of view and sample platforms involved. Here we employ a reverse transfer technique to transfer electron-irradiated single-layer MoS2 and WS2 from the TEM grid to various substrates for subsequent optical examination. The dynamics of defect creation are studied in atomic resolution on a separate sample, which allows to apply the derived statistics to larger irradiated areas on the other samples. The intensity of both the defect-bound exciton peak in photoluminescence (PL) and the defect-induced LA(M) mode in Raman spectra increase with defect density. The best substrates for defect-density determination by optical spectroscopy are polystyrene for PL and SiC and Si/SiO2 for Raman spectroscopy. These investigations represent an important step towards the quantification of defects using solely optical spectroscopy, paving the way for fast, reliable, and automatable optical quality control of optoelectronic devices.
Mechanical behavior and critical current density variation of the twisted stacked-tape slotted-core cable-in-conduit conductor under bending and axial tensile load
Authors: Liu Yang , Gao Yuanwen
Published: July 2024

The second generation (2G) high-temperature superconducting (HTS) REBCO tape and the HTS cable made by the REBCO company are considered to be alternative materials for future superconducting magnet design due to their exceptional performance. The twisted stacked-tape slotted-core (TSSC) cable-in-conduit-conductor cable, which is one of the crucial layout structures in HTS cables, has been extensively studied by numerous research groups over the years. In this paper, a 3D finite element model of the TSSC HTS cable under bending and axial tensile loads is established using the bilinear isotropic hardening model in COMSOL commercial finite element software. The mechanical behavior of the TSSC cable under bending and axial tensile loads, as well as the evolution process of overall cable performance and critical current of individual tapes inside slots, are revealed by conducting mechanical analysis and using an empirical fitting formula between the critical current density of the 2G HTS tapes and axial strain. Furthermore, optimization engineering suggestions for its structure are provided, such as reducing the twist pitch, decreasing the tape width, increasing the number of tapes, reducing the slot width while avoiding direct contact between tapes and slot walls, increasing the number of slots, increasing diameter of diversion trench and inner diameter of helical core under predominant bending loads. In the case of axial tensile loads, the aforementioned suggestions are also applicable except for the inner and outer diameters of the helical core. The critical current performance can be enhanced by augmenting the outer diameter of the helical core in this case. However, it is almost unaffected by the inner diameter of the helical core.
Effects of K excess in microstructure of (Ba0.6K0.4)Fe2As2 superconducting powders
Authors: Bellingeri Emilio , Bernini Cristina , Loria Federico , Traverso Andrea , Leveratto Alessandro , Braccini Valeria , Ballarino Amalia , Malagoli Andrea
Published: July 2024

Iron-based superconductors (IBSs) are promising for high-field applications due to their exceptional characteristics, like ultrahigh upper critical field and minimal electromagnetic anisotropy. Creating multifilamentary superconducting wires with elevated transport critical current density is essential for practical use. The Powder in Tube (PIT) technique is commonly used for this purpose, but achieving optimal results requires careful exploration of powder microstructural properties. This is particularly crucial for superconductors like (Ba,K)122, the IBS most promising from an applicative point of view, where factors such as reactivity, volatility, and toxicity of constituent elements affect phase formation. Potassium volatility often leads to nonstoichiometric conditions, introducing excess potassium in the formulation. This study focuses on the impact of potassium excess δ on the microstructural properties of the ‘optimally doped’ (Ba0.6K0.4+δ
)Fe2As2 phase (0 ⩽ δ ⩽ 0.08). Using techniques like Scanning Electron Microscopy, x-ray diffraction, and temperature-dependent magnetization measurements, we demonstrate the ability to produce nearly pure powders of the superconducting phase with controlled grain size. Our findings are relevant for PIT wire fabrication, where grain size strongly affects mechanical deformation. Grain size also influences transport properties, as observed in previous studies, where reducing grain size enhanced current-carrying capability at high magnetic fields.
Coupled Eulerian–Lagrangian model prediction of neural tissue strain during microelectrode insertion
Authors: O’Sullivan K P , Coats B
Published: July 2024

Objective. Implanted neural microelectrodes are an important tool for recording from and stimulating the cerebral cortex. The performance of chronically implanted devices, however, is often hindered by the development of a reactive tissue response. Previous computational models have investigated brain strain from micromotions of neural electrodes after they have been inserted, to investigate design parameters that might minimize triggers to the reactive tissue response. However, these models ignore tissue damage created during device insertion, an important contributing factor to the severity of inflammation. The objective of this study was to evaluate the effect of electrode geometry, insertion speed, and surface friction on brain tissue strain during insertion. Approach. Using a coupled Eulerian–Lagrangian approach, we developed a 3D finite element model (FEM) that simulates the dynamic insertion of a neural microelectrode in brain tissue. Geometry was varied to investigate tip bluntness, cross-sectional shape, and shank thickness. Insertion velocities were varied from 1 to 8 m s−1. Friction was varied from frictionless to 0.4. Tissue strain and potential microvasculature hemorrhage radius were evaluated for brain regions along the electrode shank and near its tip. Main results. Sharper tips resulted in higher mean max principal strains near the tip except for the bluntest tip on the square cross-section electrode, which exhibited high compressive strain values due to stress concentrations at the corners. The potential vascular damage radius around the electrode was primarily a function of the shank diameter, with smaller shank diameters resulting in smaller distributions of radial strain around the electrode. However, the square shank interaction with the tip taper length caused unique strain distributions that increased the damage radius in some cases. Faster insertion velocities created more strain near the tip but less strain along the shank. Increased friction between the brain and electrode created more strain near the electrode tip and along the shank, but frictionless interactions resulted in increased tearing of brain tissue near the tip. Significance. These results demonstrate the first dynamic FEM study of neural electrode insertion, identifying design factors that can reduce tissue strain and potentially mitigate initial reactive tissue responses due to traumatic microelectrode array insertion.