bluuebunny/crossref_metadata_2025 huggingface dataset:
Nonlinear impedance of a micrometer-thick layer of poly(3,4-ethylenedioxythiophen):polystyrene sulfonate
Authors: Hossein-Babaei Faramarz , Chegini Ebrahim
Published: February 2024

Poly(3,4-ethylenedioxythiophen):polystyrene sulfonate (PEDOT:PSS) is a conductive polymer composite commonly used as a hole-transporting material in various optoelectronic devices. Here, we show that both real and imaginary components of the impedance of a micrometer-thick drop-cast PEDOT:PSS layer measured perpendicular to the layer plane are strongly nonlinear and vary with both amplitude and frequency of the externally applied field. In thinner layers, the impedance approaches linearity; impedances of layers thinner than 100 nm are almost linear within the investigated field and frequency ranges. Impedance nonlinearity is more profound at low-frequencies and almost disappears above 1 kHz. The experimental results are described based on the complex polarization mechanisms prevailing at low-frequencies due to the lazy dynamics of the massive interfacial dipoles formed between PEDOT and PSS chains. The nonlinear impedance of a 2.0 μm-thick layer is utilized for the design and fabrication of a harmonic generator, a frequency adder, and a up/down converter operating at very low frequencies. Operations of a micrometer-thick drop-cast dot of PEDOT:PSS, as a second and third harmonic generator and a passive intermodulator in the frequency range of biological signals are demonstrated. Other polymer composites with large interfacial dipoles are expected to own similar properties.
Investigation on dynamic characteristics and thermal effects of single cavitation bubble in liquid nitrogen
Authors: Chen Jiacheng , Chen Tairan , Geng Hao , Huang Biao , Cao Zhixian
Published: February 2024

The objective of this paper is to investigate the dynamic characteristics and thermal effects of the single cavitation bubble in liquid nitrogen. A fully enclosed experimental platform for the single cavitation bubble in free field is established. To analyze the impact of the strong thermal effects of cryogenic fluids on the evolution process of single cavitation bubble, the room-temperature water and the liquid nitrogen in the same ambient pressure are set for comparison. According to the experimental results, the evolutions of single cavitation bubble in the room-temperature water and liquid nitrogen both experience the expansion stage, shrinkage stage, and oscillation stage, respectively. To further analyze the unsteady dynamics, a theoretical model of single cavitation bubble considering the compressibility, temperature, and phase change is introduced. The results show that the bubble radius predicted by this theoretical model is in good agreement with the experimental data. During the expansion stage, the dynamic bubble behaviors in both the room-temperature water and liquid nitrogen are governed by the liquid inertia. During the shrinkage stage, the interphase mass transfer increases the shrinkage velocity of bubble. Compared to the room-temperature water bubble, the initial pressure difference and vapor mass transfer rate of the liquid nitrogen bubble are significantly smaller. Thus, the shrinkage velocity of the liquid nitrogen is small, corresponding to weaker liquid inertia. And the bubble behaviors in liquid nitrogen are dominated by the thermal effects. For the liquid nitrogen bubble, the minimum shrinkage radius is more than 3 times that of the bubble in room-temperature water; the maximum Mach number is about 0.2 times that of the room-temperature water bubble, and the influence of compressibility on the dynamic behaviors is weaker. Besides, the maximum pressure and temperature during the shrinkage stage of liquid nitrogen bubble are significantly smaller due to the weaker shrinkage of bubble. And the oscillation cycle and overall size of the liquid nitrogen bubble are significantly larger during the oscillation stage compared to the room-temperature water bubble.
Semi-organized structures and turbulence in the atmospheric convection
Authors: Rogachevskii I. , Kleeorin N.
Published: February 2024

The atmospheric convective boundary layer (CBL) consists of three basic parts: (1) the surface layer unstably stratified and dominated by small-scale turbulence of very complex nature; (2) the CBL core dominated by the energy-, momentum-, and mass-transport of semi-organized structures (large-scale circulations), with a small contribution from small-scale turbulence produced by local structural shears; and (3) turbulent entrainment layer at the upper boundary, characterized by essentially stable stratification with negative (downward) turbulent flux of potential temperature. The energy- and flux budget theory developed previously for atmospheric stably-stratified turbulence and the surface layer in atmospheric convective turbulence is extended to the CBL core using budget equations for turbulent energies and turbulent fluxes of buoyancy and momentum. For the CBL core, we determine global turbulent characteristics (averaged over the entire volume of the semi-organized structure) as well as kinetic and thermal energies of the semi-organized structures as the functions of the aspect ratio of the semi-organized structure, the scale separation parameter between the vertical size of the structures and the integral scale of turbulence and the degree of thermal anisotropy characterized the form of plumes. The obtained theoretical relationships are potentially useful in modeling applications in the atmospheric convective boundary-layer and analysis of laboratory and field experiments, direct numerical simulations, and large-eddy simulations of convective turbulence with large-scale semi-organized structures.
Hydrodynamic characteristics of the underwater continuous launching of vehicles under rolling conditions
Authors: Lin Wei , Xu Hao , Sun Tiezhi , Duan Jinxiong
Published: February 2024

Due to the influence of initial conditions such as the tethered velocity, vertically launched underwater vehicles generate large vortex structures in the wake after leaving the launch platform. This leads to an asymmetric surface pressure distribution on the second vehicles passing through the wake, adversely affecting their attitude. The rolling of the launch platform is another critical component of the above initial conditions. This study used the Realizable k−ε model, the volume-of-fluid multiphase flow model, and overlapping grid technology to numerically simulate the launch process of sequentially launched and retrogradely launched vehicles, both with and without rolling conditions. The study conducted a comparative analysis of the evolution patterns of wake vortex intensity, pressure distribution, and air–water phase distribution for the second underwater vehicles under different conditions after their launch. The results show that under rolling conditions, the wake vortex structure exhibits curling at both the vortex head and the vortex tail, with regions of greater vorticity shifting laterally. At certain moments, rolling and vorticity have similar effects on the surface pressure of the second vehicle. The presence of rolling accelerates the expansion and compression of gas pockets within the launch tube, reducing the disturbance of gas on the retrogradely launched first vehicle and changing the rolling angle of the vehicle. In the rolling conditions, the peak water hammer force on the inner wall of the platform increases and the forces acting on the inner wall of the tube show periodic variations.
Vortex random lasing with tunable wavelength and orbital angular momentum
Authors: Bian Yaoxing , Wang Zhaona
Published: February 2024

Random lasing with special structured light field has broad application prospects in various fields. However, the complex spatial modes of random lasing increase the difficulty of light field regulation and limit its practical application. Here, a vortex random lasing with dynamically tunable wavelength and orbital angular momentum is proposed based on the microfluidic channel. Different color random lasers are integrated into the same microfluidic channel for coarse control of the emission wavelengths from 462 to 685 nm by dynamically controlling the liquid flow. A special-shape cavity with a variable size of a gain region is further constructed to finely manipulate the emission wavelengths. Moreover, the vortex random lasing with tunable orbital angular momentum mode from −50 to 50 is realized. The results provide an outstanding strategy for generating the partially coherent vortex beams and may promote the practical applications of random lasers in the fields of sensing, imaging, and communication.
Propulsive motion of an oscillating cylinder in a viscous fluid
Authors: Egorov A. , Nuriev A. , Anisimov V. , Zaitseva O.
Published: February 2024

The work is devoted to the study of the hydrodynamic mechanism of the propulsive motion of a cylindrical body of a round cross section that performs simultaneous rotational and translational oscillations in a viscous incompressible fluid. The hydrodynamics is described by a complete non-stationary system of Navier–Stokes equations, which is solved using the method of successive asymptotic expansions. Cruise regimes of motion are studied, which are formed under the conditions of harmonic rotational and multiharmonic translational oscillations. The solution obtained in the work makes it possible to determine the non-stationary hydrodynamic forces acting on the cylinder and the cruising speed of propulsive motion as nonlinear functions of the dimensionless frequency, the amplitude of rotational oscillations, and the parameters of the multiharmonic law of translational oscillations. Based on the results of the study, the influence of the structure of the law of oscillations on the efficiency of propulsion is described, the optimal parameters of the movement of the cylinder are studied, and the analysis of the limits of applicability of the constructed asymptotic theory is carried out.
Ingenious microstructure combination through topological surface state enabled MnBi2Te4/carbon fibers to be an ultrathin absorber
Authors: Chen Zegeng , Li Jun , Xu Tongtong , Zhang Zhengyu , Zhao Dongpeng , Zhou Zhongxiang
Published: February 2024

Topological insulators exhibit great attraction in the fields of spintronics and quantum anomalous Hall effect, but their interaction with electromagnetic waves is rarely explored. Herein, topological insulator MnBi2Te4, synthesized via a solid-phase melting approach, was employed to compound with conductive materials. Benefiting from the unique topological untrivial property embodied in conductive topological surface state and ingenious composite microstructure, MnBi2Te4/carbon fibers displayed an efficient conductive network and high permittivity, obtaining an ultrathin electromagnetic wave absorption capacity with a maximum effective absorbing bandwidth of 2.6 GHz at 0.9 mm and a minimum reflection loss of −38.4 dB at 1.2 mm. More importantly, its effective absorbing peaks can cover 2–18 GHz through regulating its thickness, ranging from 0.8 to 6 mm. It is deciphered that topological insulators can retain the conductivity from conductive materials to a great extent and achieve distinct performances by compositing with materials of various microstructures. This work provides valuable insights into utilizing the unique advantages of topological insulators through compositing strategy and presents a precious approach for electromagnetic wave–absorbing composite materials.
Numerical study on scroll vortex intake with non-uniform approach flow conditions
Authors: Wang Yiran , Yu Xiaodong , Zhang Shuai , Law Adrian Wing-Keung
Published: February 2024

Scroll vortex dropshafts have been adopted as an effective tool to convey flow from higher to lower elevations in drainage systems. To ensure the reliability of these dropshafts, the approach channel would normally need to achieve uniform inflow conditions through a minimum channel length requirement. In dense urbanized cities, however, these conditions are occasionally unattainable due to land space constraint. Hence, further investigation is needed to examine the effect of non-uniform inflow conditions on the flow regimes and hydraulic performance of scroll vortex dropshafts. This study aims to quantify the effect of various non-uniform inflow factors on the non-dimensional head-discharge relationship and minimum air core size of the scroll vortex dropshaft by means of computational fluid dynamics simulations. Three-dimensional numerical models with different approach channel lengths are first constructed, and simulations in uniform inflow conditions are then performed and validated by experiment data. Subsequently, simulations with non-uniform inflow conditions are carried out with varying discharges as well as cross-sectional velocity distributions. The results showed that the effect on the performance of the dropshaft depends more on the distribution profile than its peakiness. A higher water level at the entrance and dilated minimum air core size in the dropshaft are typically observed for biased inflow conditions with inward velocity distributions toward the vortex chamber center, while outward distributions toward the outer wall of the vortex chamber lead to an opposite effect. A shorter approach channel would aggravate the disparity magnitude as expected. Finally, regression equations are established based on the simulation results to enable the assessment on the effect of non-uniform inflow conditions in the design stage.
Mitigating zinc dendrites and side reactions through the incorporation of ethylenediamine additive for zinc metal anode
Authors: Wang Xu , Zhang Dongdong , Huang Hui , Chanajaree Rungroj , Qin Jiaqian , Zhang Lulu , Luo Ding , Yang Xuelin , Cao Jin
Published: February 2024

Aqueous zinc-ion battery (ZIBs) has garnered considerable attention for its economic, safe, and high-energy-density characteristics. However, impediments, such as undesirable side reactions and uneven dendrites, have restrained its progress. To overcome these challenges, diverse strategies have been proposed, with electrolyte modification emerging as a preferred approach due to its simplicity and practicality. Here, we introduced ethylenediamine (EDA) as an additive into ZnSO4 solution. Through a combination of theoretical calculations and experimental validation, we have demonstrated that EDA plays a pivotal role in reducing the free active H2O by modifying the solvation structure of Zn2+, thereby enhancing the stability of the zinc anode. Upon the incorporation of EDA into the ZnSO4 electrolyte, the symmetrical battery assembled showcased remarkable cycling stability, surpassing 1500 h at 1 mA cm−2 and 1 mAh cm−2. Notably, the coulombic efficiency and durability of Zn/Ti asymmetric batteries under identical conditions were significantly improved. Furthermore, the positive impact of EDA extended to Zn/NH4V4O10 full batteries assembled using the modified electrolyte, providing robust evidence of the practical efficacy of EDA additive. This study not only highlights the transformative potential of EDA in enhancing the stability and performance of ZIBs but also reinforces its practicality for advanced energy storage applications.
The effect of field pea grown in mixtures with spring triticale on the content of total protein and amino acids
Authors: Płaza Anna , Górski Rafał
Published: February 2024

Context Legume and cereal mixtures can provide valuable feed for livestock. Aims A field experiment was conducted in 2016–2018 to determine the effect of the proportion of mixture components and harvest date on the total protein content and the content of amino acids in mixtures of field pea (FP) and spring triticale (ST). Methods Two factors were chosen for examination, the ratio of FP to ST and harvest date (at the flowering and flat green pod stages). The mixtures of FP:ST trialled were 100:0, 0:100, 75:25, 50:50, 25:75. Key results Dry matter yield was maximised with an equal proportion of both components harvested at the flat green pod stage of FP. The highest content of total protein, asparagine, glutamic acid, tyrosine, serine, proline and glycine in the examined mixtures was found with 75% FP and 25% ST. Cysteine content was highest with 25% FP + 75% ST. A highest content of total protein and analysed amino acids, with the exception of glutamine acid and proline, was found in mixtures harvested at flowering of FP. Conclusions A mixture of FP + ST with 75 + 25% or an equal share of both components should be recommended for cultivation, harvesting at the flat green pod stage of FP. This will ensure high dry matter yields and high total protein content. Implications Growing a mixture of FP + ST with a component share of 75 + 25% yields green fodder with high protein and amino acid content, whereas mixtures with equal component shares have the highest dry matter yields.
Cochlear zinc signaling dysregulation is associated with noise-induced hearing loss, and zinc chelation enhances cochlear recovery
Authors: Bizup Brandon , Brutsaert Sofie , Cunningham Christopher L. , Thathiah Amantha , Tzounopoulos Thanos
Published: February 2024

Exposure to loud noise triggers sensory organ damage and degeneration that, in turn, leads to hearing loss. Despite the troublesome impact of noise-induced hearing loss (NIHL) in individuals and societies, treatment strategies that protect and restore hearing are few and insufficient. As such, identification and mechanistic understanding of the signaling pathways involved in NIHL are required. Biological zinc is mostly bound to proteins, where it plays major structural or catalytic roles; however, there is also a pool of unbound, mobile (labile) zinc. Labile zinc is mostly found in vesicles in secretory tissues, where it is released and plays a critical signaling role. In the brain, labile zinc fine-tunes neurotransmission and sensory processing. However, injury-induced dysregulation of labile zinc signaling contributes to neurodegeneration. Here, we tested whether zinc dysregulation occurs and contributes to NIHL in mice. We found that ZnT3, the vesicular zinc transporter responsible for loading zinc into vesicles, is expressed in cochlear hair cells and the spiral limbus, with labile zinc also present in the same areas. Soon after noise trauma, ZnT3 and zinc levels are significantly increased, and their subcellular localization is vastly altered. Disruption of zinc signaling, either via ZnT3 deletion or pharmacological zinc chelation, mitigated NIHL, as evidenced by enhanced auditory brainstem responses, distortion product otoacoustic emissions, and number of hair cell synapses. These data reveal that noise-induced zinc dysregulation is associated with cochlear dysfunction and recovery after NIHL, and point to zinc chelation as a potential treatment for mitigating NIHL.
Structure and function of the Si3 insertion integrated into the trigger loop/helix of cyanobacterial RNA polymerase
Authors: Qayyum M. Zuhaib , Imashimizu Masahiko , Leanca Miron , Vishwakarma Rishi K. , Riaz-Bradley Amber , Yuzenkova Yulia , Murakami Katsuhiko S.
Published: February 2024

Cyanobacteria and evolutionarily related chloroplasts of algae and plants possess unique RNA polymerases (RNAPs) with characteristics that distinguish them from canonical bacterial RNAPs. The largest subunit of cyanobacterial RNAP (cyRNAP) is divided into two polypeptides, β′1 and β′2, and contains the largest known lineage-specific insertion domain, Si3, located in the middle of the trigger loop and spanning approximately half of the β′2 subunit. In this study, we present the X-ray crystal structure of Si3 and the cryo-EM structures of the cyRNAP transcription elongation complex plus the NusG factor with and without incoming nucleoside triphosphate (iNTP) bound at the active site. Si3 has a well-ordered and elongated shape that exceeds the length of the main body of cyRNAP, fits into cavities of cyRNAP in the absence of iNTP bound at the active site and shields the binding site of secondary channel-binding proteins such as Gre and DksA. A small transition from the trigger loop to the trigger helix upon iNTP binding results in a large swing motion of Si3; however, this transition does not affect the catalytic activity of cyRNAP due to its minimal contact with cyRNAP, NusG, or DNA. This study provides a structural framework for understanding the evolutionary significance of these features unique to cyRNAP and chloroplast RNAP and may provide insights into the molecular mechanism of transcription in specific environment of photosynthetic organisms and organelle.
A MAP1B–cortactin–Tks5 axis regulates TNBC invasion and tumorigenesis
Authors: Inoue Hiroki , Kanda Taku , Hayashi Gakuto , Munenaga Ryota , Yoshida Masayuki , Hasegawa Kana , Miyagawa Takuya , Kurumada Yukiya , Hasegawa Jumpei , Wada Tomoyuki , Horiuchi Motoi , Yoshimatsu Yasuhiro , Itoh Fumiko , Maemoto Yuki , Arasaki Kohei , Wakana Yuichi , Watabe Tetsuro , Matsushita Hiromichi , Harada Hironori , Tagaya Mitsuo
Published: February 2024

The microtubule-associated protein MAP1B has been implicated in axonal growth and brain development. We found that MAP1B is highly expressed in the most aggressive and deadliest breast cancer subtype, triple-negative breast cancer (TNBC), but not in other subtypes. Expression of MAP1B was found to be highly correlated with poor prognosis. Depletion of MAP1B in TNBC cells impairs cell migration and invasion concomitant with a defect in tumorigenesis. We found that MAP1B interacts with key components for invadopodia formation, cortactin, and Tks5, the latter of which is a PtdIns(3,4)P2-binding and scaffold protein that localizes to invadopodia. We also found that Tks5 associates with microtubules and supports the association between MAP1B and α-tubulin. In accordance with their interaction, depletion of MAP1B leads to Tks5 destabilization, leading to its degradation via the autophagic pathway. Collectively, these findings suggest that MAP1B is a convergence point of the cytoskeleton to promote malignancy in TNBC and thereby a potential diagnostic and therapeutic target for TNBC.
Local monomer levels and established filaments potentiate non-muscle myosin 2 assembly
Authors: Quintanilla Melissa A. , Patel Hiral , Wu Huini , Sochacki Kem A. , Chandrasekar Shreya , Akamatsu Matthew , Rotty Jeremy D. , Korobova Farida , Bear James E. , Taraska Justin W. , Oakes Patrick W. , Beach Jordan R.
Published: February 2024

The ability to dynamically assemble contractile networks is required throughout cell physiology, yet direct biophysical mechanisms regulating non-muscle myosin 2 filament assembly in living cells are lacking. Here, we use a suite of dynamic, quantitative imaging approaches to identify deterministic factors that drive myosin filament appearance and amplification. We find that actin dynamics regulate myosin assembly, but that the static actin architecture plays a less clear role. Instead, remodeling of actin networks modulates the local myosin monomer levels and facilitates assembly through myosin:myosin-driven interactions. Using optogenetically controlled myosin, we demonstrate that locally concentrating myosin is sufficient to both form filaments and jump-start filament amplification and partitioning. By counting myosin monomers within filaments, we demonstrate a myosin-facilitated assembly process that establishes filament stacks prior to partitioning into clusters that feed higher-order networks. Together, these findings establish the biophysical mechanisms regulating the assembly of non-muscle contractile structures that are ubiquitous throughout cell biology.
Ion channel TRPV2 is critical in enhancing B cell activation and function
Authors: Li Cuifeng , Zhao Meng , Liu Xiaohang , Li Yuxin , Xu Bihua , Zhou Lina , Sun Xiaolin , Sun Wenbo , Kang Na , Ji Zhenglin , Li Tong , An Haoran , Wang Fei , Wu Chuan , Ye Jing-Ying , Zhang Jing-Ren , Wang Qingwen , Zhao Xiaodong , Li Zhanguo , Liu Wanli
Published: February 2024

The function of transient receptor potential vanilloid (TRPV) cation channels governing B cell activation remains to be explored. We present evidence that TRPV2 is highly expressed in B cells and plays a crucial role in the formation of the B cell immunological synapse and B cell activation. Physiologically, TRPV2 expression level is positively correlated to influenza-specific antibody production and is low in newborns and seniors. Pathologically, a positive correlation is established between TRPV2 expression and the clinical manifestations of systemic lupus erythematosus (SLE) in adult and child SLE patients. Correspondingly, mice with deficient TRPV2 in B cells display impaired antibody responses following immunization. Mechanistically, the pore and N-terminal domains of TRPV2 are crucial for gating cation permeation and executing mechanosensation in B cells upon antigen stimulation. These processes synergistically contribute to membrane potential depolarization and cytoskeleton remodeling within the B cell immunological synapse, fostering efficient B cell activation. Thus, TRPV2 is critical in augmenting B cell activation and function.
Extracting electromagnetic signatures of spacetime fluctuations
Authors: Sharmila B , Vermeulen Sander M , Datta Animesh
Published: February 2024

We present a formalism to discern the effects of fluctuations of the spacetime metric on electromagnetic radiation. The formalism works via the measurement of electromagnetic field correlations, while allowing a clear assessment of the assumptions involved. As an application of the formalism, we present a model of spacetime fluctuations that appear as random fluctuations of the refractive index of the vacuum in single, and two co-located Michelson interferometers. We compare an interferometric signal predicted using this model to experimental data from the Holometer and aLIGO. We show that if the signal manifests at a frequency at which the interferometers are sensitive, the strength and scale of possible spacetime fluctuations can be constrained. The bounds, thus obtained, on the strength and scale of the spacetime fluctuations, are also shown to be more stringent than the bounds obtained previously using astronomical observation at optical frequencies. The formalism enables us to evaluate proposed experiments such as QUEST for constraining quantum spacetime fluctuations and to design new ones.
A theoretical study on the enhanced oxygen evolution performance of NiN4-graphene by Ni nanoclusters
Authors: Shi Runchuan , Feng Shihao , Fu Zhaoming , Yang Zongxian , Zhang Xilin
Published: February 2024

Isolated metal-coordinated nitrogen embedded carbon (M–N–C) materials are potential alternatives to noble catalysts for oxygen evolution reaction (OER), and the activity of metal centers can be further modulated by adjusting the coordination environment. Recently, experimental studies have shown that the aggregation of metal atoms into small clusters or particles is inevitable during the high temperature pyrolysis, while the influences of metal clusters on the OER activity of single metal atoms in M–N–C are unclear. Herein, taking Ni-based single atom as examples, the interaction characters of NiN4 doped graphene (NiN4-graphene) with different Ni clusters were studied. The modulation effects of Ni clusters to the NiN4-graphene were systematically investigated from the geometric configurations, electronic structures, and the OER activity of the Ni single atom. It was found that the OER performance of NiN4-graphene can be remarkably improved through the addition of Ni clusters, and the lowest overpotential of 0.43 V is achieved on NiN4-graphene with the modification of Ni13 cluster, which is smaller than that of 0.69 V on NiN4-graphene. Electronic properties calculations showed that the charge transfer from Ni clusters to NiN4-graphene will alter the density of states of Ni single atom near the Fermi level, which promotes the charge transfer from NiN4-graphene to oxygen containing products and optimizes the adsorption strength of oxygen intermediate to close to the ideal adsorption free energy of 2.46 eV by enhancing the hybridization interaction between the O-p orbitals and the Ni-dxz
, Ni-dyz
orbitals, and finally leading to an enhanced OER activity. The current findings highlight the important role of metal clusters on improving the catalytic performance of M–N–C materials, which benefits for the rational design of M–N–C catalysts with high catalytic activity.
Acoustic attenuation of side-branched Helmholtz resonator with embedded apertures in grazing flow ducts
Authors: Cao Jilai , Huang Sibo , Yu Xinhai , Li Yong
Published: February 2024

Refrigeration equipment is widely used on a daily basis in residential, commercial and industrial applications, but the aerodynamic performance and noise problems remain a tragic problem. Acoustic duct silencers as an effective noise elimination solution have received great and continuing interest in noise control engineering to mitigate acoustic instability. In the presence of grazing flow, acoustic-attenuation performances of duct silencers decrease greatly due to the vortices and flow oscillations generated in the duct. In this work, the acoustic-attenuation performances of side-branched metasurfaces composed of Helmholtz resonators with embedded apertures (HREAs) in a flow duct were systematically investigated. HREAs are capable of efficiently weakening the flow-induced noise by damping the vortices and flow oscillations with an improved acoustic impedance design, which leads to better acoustic-attenuation performance. Furthermore, the optimal attenuation performance of the proposed HREAs under grazing flow was demonstrated by tuning the diameter and extending the length of the embedded apertures. The proposed structures, with double HREAs separated at a distance or arranged at the same location, can realize a higher efficient and broadband acoustic attenuation performance. The results show outstanding noise-attenuation performance and may inspire the development of highly efficient, thin and tunable acoustic mufflers for refrigeration equipment.
Investigation of a neural implicit representation tomography method for flow diagnostics
Authors: Kelly Dustin , Thurow Brian
Published: February 2024

In this work, a new gridless approach to tomographic reconstruction of 3D flow fields is introduced and investigated. The approach, termed here as FluidNeRF, is based on the concept of volume representation through Neural Radiance Fields (NeRF). NeRF represents a 3D volume as a continuous function using a deep neural network. In FluidNeRF, the neural network is a function of 3D spatial coordinates in the volume and produces an intensity of light per unit volume at that position. The network is trained using the loss between measured and rendered 2D projections similar to other multi-camera tomography techniques. Projections are rendered using an emission-based integrated line-of-sight method where light rays are traced through the volume; the network is used to determine intensity values along the ray. This paper investigates the influence of the NeRF hyperparameters, camera layout and spacing, and image noise on the reconstruction quality as well as the computational cost. A DNS-generated synthetic turbulent jet is used as a ground-truth representative flow field. Results obtained with FluidNeRF are compared to an adaptive simultaneous algebraic reconstruction technique (ASART), which is representative of a conventional reconstruction technique. Results show that FluidNeRF matches or outperforms ASART in reconstruction quality, is more robust to noise, and offers several advantages that make it more flexible and thus suitable for extension to other flow measurement techniques and scaling to larger-scale problems.
Generalizing infrastructure inspection: step transfer learning aided extreme learning machine for automated crack detection in concrete structures
Authors: Sohaib Muhammad , Hasan Md Junayed , Chen Jianxin , Zheng Zhonglong
Published: February 2024

Identification of damage and selection of a restoration strategy in concrete structures is contingent upon automatic inspection for crack detection and assessment. Most research on deep learning models for autonomous inspection has focused solely on measuring crack dimensions, omitting the generalization power of a model. This research utilizes a novel step transfer learning (STL) added extreme learning machine (ELM) approach to develop an automatic assessment strategy for surface cracks in concrete structures. STL is helpful in mining generalized abstract features from different sets of source images, and ELM helps the proposed model overcome the optimization limitations of traditional artificial neural networks. The proposed model achieved at least 2.5%, 4.8%, and 0.8% improvement in accuracy, recall, and precision, respectively, in comparison to the other studies, indicating that the proposed model could aid in the automated inspection of concrete structures, ensuring high generalization ability.
A light weight multi-scale feature fusion steel surface defect detection model based on YOLOv8
Authors: Xie Weining , Sun Xiaoyong , Ma Weifeng
Published: February 2024

In industrial production, the steel surface may incur different defects owing to the influence of external factors, thereby affecting the performance of steel. With the increasing requirements for steel quality, achieving efficient detection of steel surface defects is a difficult problem that urgently needs to be solved. Traditional steel surface defect detection methods are limited by poor detection performance and slow detection speed. Therefore, a model named LMS-YOLO, based on YOLOv8, is proposed in this paper for achieving efficient steel surface defect detection. Firstly, in backbone, the light weight multi-scale mixed convolution (LMSMC) module is designed to fuse with C2f to obtain C2f_LMSMC, so as to extract the features of different scales for fusion and achieve the light weight of the network. Meanwhile, the proposed efficient global attention mechanism was added to backbone to enhance cross dimensional information interaction and feature extraction capabilities, and to achieve a more efficient attention mechanism. In neck, using channel tuning to achieve better cross scale fusion in BiFPN. Finally, the model uses three independent decoupled heads for regression and classification, and replaces CIoU with NWD as the regression loss to enhance the effect of detecting small scale defects. The experimental results showed that LMS-YOLO achieved 81.1 mAP and 61.3 FPS on NEU-DET, 80.5 mAP and 61.3 FPS on GC10-DET, respectively. The mAP increased by 2.8 and 4.7 compared to YOLOv8, and decreased by 17.4% in floating point operations (GFLOPs) and 34.2% in parameters (Params), which indicates that the model proposed in this paper has a better comprehensive performance compared with other methods in steel surface defect detection.
In-depth S/TEM observation of Ti–Hf and Ta–Hf-doped Nb3Sn layers
Authors: Banno Nobuya , Moronaga Taku , Hara Toru , Asai Koki , Yagai Tsuyoshi
Published: February 2024

In superconducting Nb3Sn layers with coherence lengths of approximately 3 nm, grain boundaries act as effective pinning sites. Thus, grain refinement is an essential issue that directly affects the superconducting critical characteristics of the Nb3Sn layer. In recent years, Hf addition to Nb3Sn wires co-doped with Ta has attracted notable interest as a method that enables grain refinement down to several tens of nm. In-depth characterization of the Nb3Sn grain morphology in Hf-doping is crucially important to correlate the microstructure with the flux pinning characteristics. In this article, the grain morphologies of Ti–Hf and Ta–Hf-doped Nb3Sn layers were clarified by scanning transmission electron microscopy (STEM) and TEM-based automated crystal orientation mapping (ACOM-TEM). STEM/energy dispersive x-ray spectroscopy (EDS) revealed no significant oxide precipitates in our samples. The grain size distribution was attained by ACOM-TEM. Although Hf-doping attained a grain refinement effect in the Nb3Sn layer in both doping cases, the degree of this effect was relatively small for Ti–Hf. Kernel average misorientation analysis by scanning electron microscopy-electron backscattered diffraction unveiled no appreciable difference between the internal strain states of the Nb-alloy parent phases in Ti–Hf and Ta–Hf. One remarkable new finding through STEM/EDS was the presence of a Cu–Hf compound phase in the Nb3Sn layer. The Cu–Hf compound sounds analogous to the Cu–Ti compounds that form when Nb–47Ti with Cu matrix is heat treated. The STEM/EDS maps revealed a larger amount of Cu flow from the Cu–Sn side along the grain boundaries. The large Cu deposition on the grain boundaries might facilitate grain growth in Nb3Sn. Those findings make a novel contribution to the literature as they provide a deep insight into Nb3Sn phase formation via Hf doping.
A modified motor-clutch model reveals that neuronal growth cones respond faster to soft substrates
Authors: Cifuentes Laura Pulido , Athamneh Ahmad I. M. , Efremov Yuri , Raman Arvind , Kim Taeyoon , Suter Daniel M.
Published: February 2024

Neuronal growth cones sense a variety of cues including chemical and mechanical ones to establish functional connections during nervous system development. Substrate-cytoskeletal coupling is an established model for adhesion-mediated growth cone advance; however, the detailed molecular and biophysical mechanisms underlying the mechanosensing and mechanotransduction process remain unclear. Here, we adapted a motor-clutch model to better understand the changes in clutch and cytoskeletal dynamics, traction forces, and substrate deformation when a growth cone interacts with adhesive substrates of different stiffnesses. Model parameters were optimized using experimental data from Aplysia growth cones probed with force-calibrated glass microneedles. We included a reinforcement mechanism at both motor and clutch level. Furthermore, we added a threshold for retrograde F-actin flow that indicates when the growth cone is strongly coupled to the substrate. Our modeling results are in strong agreement with experimental data with respect to the substrate deformation and the latency time after which substrate-cytoskeletal coupling is strong enough for the growth cone to advance. Our simulations show that it takes the shortest time to achieve strong coupling when substrate stiffness was low at 4 pN/nm. Taken together, these results suggest that Aplysia growth cones respond faster and more efficiently to soft than stiff substrates.
A guide to improving the design and analysis of observational studies on the long-term safety of topical corticosteroids
Authors: Drucker Aaron M , Austin Peter C , Harvey Jane , Lax Stephanie J , Tadrous Mina , Thomas Kim S
Published: February 2024

Despite a long track-record of use, patients and clinicians continue to have concerns about the safety of topical corticosteroids (TCS). Observational studies in routinely collected health data provide an opportunity to address those concerns but are challenging to conduct in a way that minimizes bias and confounding. We review challenges and potential solutions for the conduct of observational studies on the long-term safety of TCS.
Albumin influences leucocyte FcRn expression in the early days of kidney transplantation
Authors: Boulard Pierre , Azzopardi Nicolas , Levard Romain , Cornec Jean-Marie , Lamamy Juliette , Prieur Bérénice , Demattei Marie-Véronique , Watier Hervé , Gatault Philippe , Gouilleux-Gruart Valérie
Published: February 2024

FcRn, a receptor originally known for its involvement in IgG and albumin transcytosis and recycling, is also important in the establishment of the innate and adaptive immune response. Dysregulation of the immune response has been associated with variations in FcRn expression, as observed in cancer. Recently, a link between autophagy and FcRn expression has been demonstrated. Knowing that autophagy is strongly involved in the development of reperfusion injury in kidney transplantation and that albuminemia is transiently decreased in the first 2 weeks after transplantation, we investigated variations in FcRn expression after kidney transplantation. We monitored FcRn levels by flow cytometry in leukocytes from 25 renal transplant patients and considered parameters such as albumin concentrations, estimated glomerular filtration rate, serum creatinine, serum IgG levels, and ischaemia/reperfusion time. Two groups of patients could be distinguished according to their increased or non-increased FcRn expression levels between days 2 and 6 (d2–d6) post-transplantation. Leukocyte FcRn expression at d2–d6 was correlated with albumin concentrations at d0–d2. These results suggest that albumin concentrations at d0–d2 influence FcRn expression at d2–d6, raising new questions about the mechanisms underlying these original observations.
Fundamental physics with ESPRESSO: a new determination of the D/H ratio towards PKS1937-101
Authors: Guarneri Francesco , Pasquini Luca , D’Odorico Valentina , Cristiani Stefano , Cupani Guido , Marcantonio Paolo Di , Hernández J I González , Martins C J A P , Mascareño Alejandro Suárez , Milaković Dinko , Molaro Paolo , Murphy Michael T , Nunes Nelson J , Palle Enric , Pepe Francesco , Rebolo Rafael , Santos Nuno C , Santos Ricardo Génova , Schmidt Tobias M , Sousa Sérgio G , Sozzetti Alessandro , Trost Andrea
Published: February 2024

Primordial abundances of light elements are sensitive to the physics of the early Universe and can directly constrain cosmological quantities, such as the baryon-to-photon ratio $\eta _{10}$, the baryon density, and the number of neutrino families. Deuterium is especially suited for these studies: its primordial abundance is sensitive and monotonically dependent on $\eta _{10}$, allowing an independent measurement of the cosmic baryon density that can be compared, for instance, against the Planck satellite data. The primordial deuterium abundance can be measured in high H i column density absorption systems towards distant quasars. We report here a new measurement, based on high-resolution ESPRESSO data, of the primordial D i abundance of a system at redshift $z \sim 3.572$, towards PKS1937-101. Using only ESPRESSO data, we find a D /H ratio of $2.638\pm 10^{-5}$, while including the available UVES data improves the precision, leading to a ratio of $2.608 \pm 10^{-5}$. The results of this analysis agree with those of the most precise existing measurements. We find that the relatively low column density of this system ($\log {N_{\rm H_I}/ {\rm cm}^{-2}}\sim 18$) introduces modelling uncertainties, which become the main contributor to the error budget.
Role of AGN and star formation feedback in the evolution of galaxy outflows
Authors: Clavijo-Bohórquez William E , de Gouveia Dal Pino Elisabete M , Melioli Claudio
Published: February 2024

We conducted 3D-magnetohydrodynamic simulations to investigate the feedback processes in the central 1-kpc scale of galaxies hosting both active star formation (SF) and an active galactic nucleus (AGN) wind. Our simulations naturally generated a turbulent and clumpy interstellar medium driven by SF evolution. We found that the AGN-wind duty cycle plays a crucial role in shaping the evolution of the outflows. A single duty cycle (which can repeat several times over the galaxy lifetime) consists of an active, a remnant and an inactive phase, lasting up to 1.5 Myr in our simulations. The duration of the cycle increases with larger star formation rate (SFR) and smaller AGN-wind power (tested for luminosities 1042–1044 erg s−1 and SFR = 1–1000 M⊙ yr−1). The feedback on SF, whether positive or negative, depends on various factors, including the AGN outflow opening angle, power, and phase of activity, as well as the initial SFR. The passage of the AGN wind enhances SF in a ring around it, resembling the structures observed in ULIRGs (Ultraluminous Infrared Galaxies) and LINERS (low-ionization nuclear emission-line region), and is stronger for larger AGN power or SFR. Also, a higher SFR enhances the mixing of interstellar matter with the AGN wind, resulting in a greater number of colder, denser structures with volume filling factors ∼0.02 to 0.12 and velocities comparable to those observed in Seyferts and LINERs, but smaller than those observed in ULIRGs. The efficiency of the AGN wind in transporting mass to kiloparsec distances diminishes with increasing SFR. The mass-loss rates range from 50 to 250 M⊙ yr−1 within the initial 2 Myr of evolution, which aligns with observed rates in nearby Seyferts and ULIRGs.
La Silla-QUEST RR Lyrae star survey II: the Crater II tidal streams
Authors: Coppi P S , Zinn R , Baltay C , Rabinowitz D , Girard T , Howard R , Ment K , Rahman R
Published: February 2024

We describe photometry improvements in the La Silla-Quest RR Lyrae star (RRLS) survey that enable it to reach distances from the Sun (d⊙) ∼140 kpc. We report the results of surveying ∼300 deg2 of sky around the large, low-surface-brightness Crater II dwarf spheroidal galaxy. At d⊙ >80 kpc, we find a large overdensity of RRLS that extends beyond the traditional isophotal contours used for Crater II. The majority of these RRLS (34) have a linear distribution on the sky, extending over 15°, that runs through Crater II and is oriented along Crater II’s proper motion vector. We hypothesize that this unlikely distribution traces extended tidal streams associated with Crater II. To test this, we search for other Crater II stellar populations that should be in the streams. Using Gaia proper motion data, we isolate ≈ 17 candidate stars outside of Crater II that are consistent with being luminous stars from the Crater II Red Giant Branch (RGB). Their spatial distribution is consistent with the RRLS one. The inferred streams are long, spanning a distance range ∼80–135 kpc from the Galactic Centre. They are oriented at a relatively small-angle relative to our line of sight (∼25°), which means some stream stars are likely projected onto the main body of the galaxy. Comparing the numbers of RRLS and RGB candidate stars found in the streams to those in the main galaxy, we estimate Crater II has lost $\gtrsim 30~{{\rm per\ cent}}$ of its stellar mass.