bluuebunny/crossref_metadata_2025 huggingface dataset:
Determination of elastic constants in complex-shaped materials through vibration-mode-pattern-matching-assisted resonant ultrasound spectroscopy
Authors: Yamamoto Go , Sakuda Yuto
Published: May 2024

The rapid advances in the additive manufacturing technology has led to the emergence of structural materials with arbitrary geometries that were previously challenging to produce using conventional machining techniques. Elastic constants are key mechanical parameters in structural material design; however, their accurate determination becomes challenging when dealing with materials possessing intricate geometries, which make traditional mechanical testing methods less practical. In this study, we accurately determined the elastic constants of a cuboid-shaped SUS304 specimen by combining resonant ultrasonic spectroscopy with the vibration-pattern-pairing method. The proposed method was then applied to a truss-shaped SUS304 specimen. To ensure the consistency of vibration modes, vibration patterns were matched by assessing the cosine similarity between contour plots, which depict the vibration patterns obtained from each of the three planes of the experimental specimen and those generated from a finite element model based on their color map. The measured elastic constants of the truss-shaped specimen were in reasonable agreement with those of the cuboid-shaped specimen and those obtained from tensile tests conducted on specimens obtained from an SUS304 block—the source material for the cuboid- and truss-shaped specimens. The optimization process for the elastic constants exhibited reproducibility, highlighting the efficacy of our approach for quantifying the elastic constants of materials with arbitrary geometries. The proposed method can assist material designers in accurately and efficiently determining the elastic constants of materials with intricate three-dimensional geometries and mechanical anisotropy.
778.1 nm distributed feedback lasers for Rb two-photon atomic systems with sub-4 kHz linewidths
Authors: Di Gaetano E. , Keliehor B. , Gallacher K. , Griffin P. F. , Sorel M. , Riis E. , Paul D. J.
Published: May 2024

A new epitaxial layer design with a double mode expander layer, high refractive index claddings, and an aluminum-free active area has been used to demonstrate distributed feedback lasers operating at 778.1 nm wavelength with reduced Lorentzian linewidth aimed at miniature atomic clock applications. The design also reduces the vertical beam divergence to improve the modal matching with optical fibers as well as maintain the high power output and reduce the emission linewidth. The lasers demonstrate single-mode operation with an over 35 dB side-mode suppression ratio, a power output ≤58 mW, a coupling efficiency to tapered fibers ≤40%, and a Lorentzian linewidth of 3.7 kHz. The performance allowed the free-running distributed feedback lasers to demonstrate spectroscopy of Rb vapor, which resolved the 85Rb and 87Rb two-photon transitions.
An ultrahigh frequency dielectric sensor for microdroplet detection using a split ring resonator-based microfluidic chip
Authors: Teymoori Morteza , Yalcinkaya Arda Deniz
Published: May 2024

Metamaterials have drawn interest in the sensor community due to their extreme dielectric-sensitive resonant behavior. Although these structures are studied in a wide range of frequencies, the ultrahigh frequencies are of special interest due to their compatibility with RF electronics. Unlike spectroscopic methods, where each material has its specific fingerprint, the response of these resonant structures depends on the electromagnetic properties, the volume of the material under test, and the resonator's design itself. Thus, implementing a metamaterial-based sensor for biological and chemical applications requires some mechanism to fix the sample's location and volume. Since most biological and chemical samples are liquids, microfluidics is the most promising candidate for this task. Here, we propose a dielectric sensing platform with a cost-effective fabrication method that allows fluid detection inside the microfluidic channel. The device proposed here is designed numerically, fabricated and measured, and finally validated via an analytical lumped model. It consists of a microstrip line coupled with a split ring resonator as the transducer and a microfluidic structure to control the sample and generate microdroplets. The fluid under test inside the microfluidic channel can be characterized based on the change in its dielectric constant or loss factor. The device shows a 600 kHz resonance shift in response to the dielectric change in sample volumes as low as 10 nl. We also demonstrate the platform's capability to generate and detect octanol–water microdroplets. The method reported here offers a fast prototyping method suitable for various microfluidic sensing applications.
Operando nano-mapping of sodium-diglyme co-intercalation and SEI formation in sodium ion batteries' graphene anodes
Authors: Chen Yue , Zhang Shaohua , Zhang Weijian , Quadrelli Alessio , Jarvis Samuel , Chen Jing , Lu Hongyi , Mangayarkarasi Nagarathinam , Niu Yubiao , Tao Jianming , Zhang Long , Li Jiaxin , Lin Yingbin , Huang Zhigao , Kolosov Oleg
Published: May 2024

Diglyme molecular solvated sodium ion complexes enable the superfast co-intercalation/de-intercalation into graphite interlayers, providing unprecedented prospects for the application of low-dimensional graphitic carbon as fast-charge sodium ion battery anode materials. A thorough understanding of this novel co-intercalation process and resulting solid-electrolyte interphase (SEI) is essential for improving the electrochemical performance of co-intercalation-based high-capacity energy storage systems. This work presents the real-space operando observation of SEI formation and Na-diglyme co-intercalation in the few-layer graphene (FLG) anode as a relevant model of a graphitic anode. The micrometer-sized FLG grid on a nickel current collector was fabricated as a model sample, allowing direct comparative studies using complementary techniques. A reversible sodium-diglyme co-intercalation into the graphene grid was confirmed by Raman spectroscopy, the nanomechanical properties of electrolyte decomposition products on graphene anode and Ni current collector surfaces were studied by ultrasonic force microscopy, and the chemical components of the SEI were confirmed by x-ray photoelectron spectroscopy mapping. We observed a mechanically soft SEI layer formed on the carbon anode surface compared with the electrode current collector surface within the low voltage region (<0.3 V vs Na+/Na), this SEI layer does not affect the reversible Na-diglyme co-intercalations into FLG. At the same time, the SEI layer formed on the Ni current collector mainly contains stiff and thin inorganic species and is electrochemically stable at low voltage regions. Our results clarify the SEI formation behavior on the FLG anode surface in the diglyme electrolyte, providing experimental evidence for the fundamental understanding of Na-diglyme co-intercalation.
Hydrodynamics of light levitated droplet evolution
Authors: Jiang Pengcheng , Yang Yijing , Chen Rong , Zhu Xun , Ye Dingding , Yang Yang , Wang Hong , An Liang , Liao Qiang
Published: May 2024

Light levitation of droplets over a locally heated gas–liquid interface by an infrared focus laser has been recently reported, but the hydrodynamics of light levitated droplet evolution remains unclear. Herein, we report that the condensed droplet experiences a periodic damped vortex motion process before evolving to a stably levitated droplet. In the later stage of the periodic damped vortex motion, the velocity decay rate is linearly proportional to the growth of condensed droplets. The linear scaling factor approximates the dynamic viscosity of the ambient fluid, which is analogous to the shear stress–shear relationship in the Newtonian friction law. This study deepens the understanding of the underlying mechanism of light levitated droplet evolution.
Electronic structure–property relationship in an Al0.5TiZrPdCuNi high-entropy alloy
Authors: Babić Emil , Figueroa Ignacio A. , Mikšić Trontl Vesna , Pervan Petar , Pletikosić Ivo , Ristić Ramir , Salčinović Fetić Amra , Skoko Željko , Starešinić Damir , Valla Tonica , Zadro Krešo
Published: May 2024

The valence band (VB) structure of an Al0.5TiZrPdCuNi high-entropy alloy (HEA) obtained using x-ray photoelectron spectroscopy has been compared to that recently calculated by Odbadrakh et al. [J. Appl. Phys. 126, 095104 (2019)]. Both the experimental and theoretical VBs show a split-band structure, typical for alloys consisting of the early (TE) and late (TL) transition metals. Accordingly, several electronic structure (ES) properties of this alloy, both in the glassy and crystalline state, are compared with those of similar TE-TL alloys. The comparison shows a strong effect of alloying with Al on the density of states at the Fermi level, N(EF), and on the magnetic susceptibility of Al0.5TiZrPdCuNi HEA, similar to that in conventional glassy alloys, such as Zr-Cu-Al ones. Despite some similarity in the theoretical and experimental density of states of the VBs, there are significant differences between them, which should be taken into account in any future studies of ES in HEAs and other compositionally complex alloys.
Unsupervised learning enables multicolor synchronous fluorescence microscopy without cytoarchitecture crosstalk
Authors: Lu Bolin , Ding Zhangheng , Ning Kefu , Zhang Xiaoyu , Li Xiangning , Zhao Jiangjiang , Xie Ruiheng , Shen Dan , Hu Jiahong , Jiang Tao , Chen Jianwei , Gong Hui , Yuan Jing
Published: May 2024

In multicolor fluorescence microscopy, it is crucial to orient biological structures at a single-cell resolution based on precise anatomical annotations of cytoarchitecture images. However, during synchronous multicolor imaging, due to spectral mixing, the crosstalk from the blue signals of 4′,6-diamidino-2-phenylindole (DAPI)-stained cytoarchitecture images to the green waveband hinders the visualization and identification of green signals. Here, we proposed a deep learning-based framework named the crosstalk elimination and cytoarchitecture enhancement pipeline (CECEP) to simultaneously acquire crosstalk-free signals in the green channel and high-contrast DAPI-stained cytoarchitecture images during multicolor fluorescence imaging. For the CECEP network, we proposed an unsupervised learning algorithm named the cytoarchitecture enhancement network (CENet), which increased the signal-to-background ratio (SBR) of the cytoarchitecture images from 1.5 to 15.0 at a reconstruction speed of 25 Hz for 1800 × 1800 pixel images. The CECEP network is widely applicable to images of different quality, different types of tissues, and different multicolor fluorescence microscopy. In addition, the CECEP network can also facilitate various downstream analysis tasks, such as cell recognition, structure tensor calculation, and brain region segmentation. With the CECEP network, we simultaneously acquired two specific fluorescence-labeled neuronal distributions and their colocated high-SBR cytoarchitecture images without crosstalk throughout the brain. Experimental results demonstrate that our method could potentially facilitate multicolor fluorescence imaging applications in biology, such as revealing and visualizing different types of biological structures with precise locations and orientations.
Strong symmetry breaking rhythms created by folded nodes in a pair of symmetrically coupled, identical Koper oscillators
Authors: Epstein Irving R. , Awal Naziru M. , Kaper Tasso J. , Vo Theodore
Published: May 2024

The Koper model is a prototype system with two slow variables and one fast variable that possesses small-amplitude oscillations (SAOs), large-amplitude oscillations (LAOs), and mixed-mode oscillations (MMOs). In this article, we study a pair of identical Koper oscillators that are symmetrically coupled. Strong symmetry breaking rhythms are presented of the types SAO–LAO, SAO–MMO, LAO–MMO, and MMO–MMO, in which the oscillators simultaneously exhibit rhythms of different types. We identify the key folded nodes that serve as the primary mechanisms responsible for the strong nature of the symmetry breaking. The maximal canards of these folded nodes guide the orbits through the neighborhoods of these key points. For all of the strong symmetry breaking rhythms we present, the rhythms exhibited by the two oscillators are separated by maximal canards in the phase space of the oscillator.
Experimental setup for thermal measurements at the nanoscale using a SThM probe with niobium nitride thermometer
Authors: Swami R. , Julié G. , Le-Denmat S. , Pernot G. , Singhal D. , Paterson J. , Maire J. , Motte J. F. , Paillet N. , Guillou H. , Gomès S. , Bourgeois O.
Published: May 2024

Scanning Thermal Microscopy (SThM) has become an important measurement technique for characterizing the thermal properties of materials at the nanometer scale. This technique requires a SThM probe that combines an Atomic Force Microscopy (AFM) probe and a very sensitive resistive thermometer; the thermometer being located at the apex of the probe tip allows for the mapping of temperature or thermal properties of nanostructured materials with very high spatial resolution. The high interest of the SThM technique in the field of thermal nanoscience currently suffers from a low temperature sensitivity despite its high spatial resolution. To address this challenge, we developed a high vacuum-based AFM system hosting a highly sensitive niobium nitride (NbN) SThM probe to demonstrate its unique performance. As a proof of concept, we utilized this custom-built system to carry out thermal measurements using the 3ω method. By measuring the V3ω voltage on the NbN resistive thermometer under vacuum conditions, we were able to determine the SThM probe’s thermal conductance and thermal time constant. The performance of the probe is demonstrated by performing thermal measurements in-contact with a sapphire sample.
Core/shell architecture made from Mie-resonant silicon nanoparticle: Design, fabrication, and photonic applications
Authors: Sugimoto Hiroshi , Fujii Minoru
Published: May 2024

A silicon nanoparticle with a diameter of 100–300 nm possesses electric- and magnetic-type Mie resonances in the visible to near-infrared ranges and is recognized as a novel nanoplatform that can be used for light propagation control, light–matter interaction enhancement, structural coloration, bio-imaging and -sensing, etc. The functions of a silicon nanoparticle can be greatly extended by decorating the surface with various passive and active materials. In this mini-review, we introduce a recent development of a core/shell architecture made from Mie resonant silicon nanoparticles. We start from the state-of-the-art of the production of high-quality silicon nanoparticles. We then introduce fabrication processes of the core/shell architectures for a variety of shell materials that modify the properties of silicon nanoparticles and introduce new functions. The shell materials include passive low-refractive index materials, materials of tunable optical properties, fluorescence dyes, transition metal dichalcogenides, and noble metals with surface plasmon resonances. Finally, we will discuss our perspective for the development of future silicon-based core/shell architectures.
Reaction mechanisms for electrical doping of organic semiconductors using complex dopants
Authors: Marder Seth R. , Barlow Stephen
Published: May 2024

Electrical doping of organic semiconductors (OSCs) can be achieved using simple one-electron reductants and oxidants as n- and p-dopants, respectively, but for such dopants, increased doping strength is accompanied by increased sensitivity to ambient moisture and/or oxygen. “Indirect” or “complex” dopants—defined here as those that generate OSC radical cations or anions via pathways more complex than a single simple electron transfer, i.e., by multistep reactions—represent a means of circumventing this problem. This review highlights the importance of understanding the reaction mechanisms by which such dopants operate for: (i) ensuring a researcher knows the composition of a doped material; (ii) predicting the thermodynamic feasibility of achieving doping with related dopant:OSC combinations; and (iii) predicting whether thermodynamically feasible doping reactions are likely to be rapid or slow, or to require subsequent activation. The mechanistic information available to date for some of the wide variety of complex n- and p-dopants that have been reported is then reviewed, emphasizing that in many cases our knowledge is far from complete.
Complexified synchrony
Authors: Lee Seungjae , Braun Lucas , Bönisch Frieder , Schröder Malte , Thümler Moritz , Timme Marc
Published: May 2024

The Kuramoto model and its generalizations have been broadly employed to characterize and mechanistically understand various collective dynamical phenomena, especially the emergence of synchrony among coupled oscillators. Despite almost five decades of research, many questions remain open, in particular, for finite-size systems. Here, we generalize recent work [Thümler et al., Phys. Rev. Lett. 130, 187201 (2023)] on the finite-size Kuramoto model with its state variables analytically continued to the complex domain and also complexify its system parameters. Intriguingly, systems of two units with purely imaginary coupling do not actively synchronize even for arbitrarily large magnitudes of the coupling strengths, |K|→∞, but exhibit conservative dynamics with asynchronous rotations or librations for all |K|. For generic complex coupling, both traditional phase-locked states and asynchronous states generalize to complex locked states, fixed points off the real subspace that exist even for arbitrarily weak coupling. We analyze a new collective mode of rotations exhibiting finite, yet arbitrarily large rotation numbers. Numerical simulations for large networks indicate a novel form of discontinuous phase transition. We close by pointing to a range of exciting questions for future research.
Study on the ultrasonic cavitation damage to early atherosclerotic plaque
Authors: Lei Weirui , Li Ang , Zhou Kun , Zou Xiao , Hu Jiwen , Qian Shengyou
Published: May 2024

Ultrasonic cavitation can damage surrounding material and be used for destruction of the target tissue. In this paper, we investigated the interaction between atherosclerotic plaque (AP) and cavitation bubbles to determine whether the mechanical effect of cavitation damage could be potentially useful in therapy for treating atherosclerotic plaques. A two-bubble–fluid–solid model was established to study the dynamic behavior of bubbles near the AP and the AP damage by ultrasound-induced cavitation. A low-intensity focused ultrasound (LIFU) transducer was used for testing cavitation-based AP damage. We found that the nonlinear oscillation of bubbles causes the relative positions of the bubbles to shift, either toward or away from one another, these phenomena lead to changes in the bond failure rate between the fiber bundles, and the value of BRF exhibits an upward trend, this is the reason why the fibers suffered from reversible stretching and compressing. However, the AP damage is irreversible and diminishes as the number of cycles in the ultrasonic burst. It appears that the bigger the radii, regardless of whether the bubble (3 − i)’s and bubble i's radii are equal, the greater the AP damage. Ultrasonic cavitation therapy may not be appropriate for advanced AP patients, and the calcified tissue has a greater impact on the stability of the plaque. The damage area should be strictly selected. Additionally, the tissue damage phenomenon was found in experimental results. This work shows that the severity of AP damage is correlated with acoustic parameters and the surrounding environment from both simulation and experimental perspectives. The results show that ultrasonic cavitation may provide a new choice for the treatment of AP.
Highly reproducible synthesis of boron arsenide with high thermal conductivity
Authors: Lee Dongwook , Kim Jaehoon , Kang Joon Sang
Published: May 2024

Cubic boron arsenide (BAs) is a subject of considerable interest in thermal science due to its exceptionally high thermal conductivity. However, the inherent long mean free path of phonons renders the thermal conductivity of BAs highly susceptible to impurity concentration. In this study, we present a catalyst assisted crystal synthesis approach to achieve high-quality cubic BAs, leveraging Pt as a catalyst in the synthesis process. Our thermal conductivity measurements reveal that over 90% of the samples in a batch exhibit thermal conductivity values exceeding 1000 W·m−1·K−1. The robustness of the synthesis method is further validated through thermal conductivity mapping and Raman spectroscopy. These findings offer valuable insights for enhancing the quality of BAs crystals and hold promise for practical applications.
Strain regulated giant negative thermal expansion in hexagonal sulfides (Ni1−xFex)1−
δ
S
Authors: Lin Jianchao , Zhang Qinghua , Tong Peng , Zhang Xuekai , Zhu Xiaoguang , Shi Tongfei , Lu Wenjian , Chen Jie , Wu Yaoda , Lu Huaile , He Lunhua , Bai Bo , Jiang Yong , Song Wenhai , Sun Yuping
Published: May 2024

Strain engineering is an alternative to chemical modification in manipulating functionalities of materials. Here, we report the lattice strain could relax the abrupt phase transition of (Ni1−xFex)1−δS and lead to an excellent negative thermal expansion (NTE) effect. The high-resolution scanning transmission electron microscope and extended x-ray absorption fine structure unambiguously demonstrate that parallel Ni3S4-type nanosheets could be introduced into the matrix lattice by increasing the δ value. By forming the Ni(Fe)-S-Ni(Fe) bonds, the (1–11) plane of nanosheets epitaxially grows on the (002) plane of the hexagonal matrix. Those bonds are strong enough to bear the large lattice mismatch along the interface as the phase transition occurs. As the concentration of nanosheets increases, the weak and inhomogeneous strain in matrix lattice becomes strong and uniform, expanding the NTE window in different ways. This result opens an unconventional avenue for designing NTE materials and extends the research scope of lattice strain as well.
Moving contact line dynamics for capillary-driven microfluidics in wetting transition regime
Authors: Qiao Du , Li Hongxia , Chen Xuhui , Li Jiahao , Wang Xiyang , Zhao Danyang , Li Honglin , Qian Xuhong
Published: May 2024

The dynamics of moving contact lines (MCLs) dominate the behavior of capillary-driven microfluidics, which underlie many applications including microfluidic chips. The capillary displacement dynamics in the quasi-static regime has been extensively studied. However, the behavior of MCLs in the dynamic wetting transition regime remains largely unexplored, and previously established MCL dynamic models may be inadequate. In this study, a novel capillary displacement experiment is introduced, which is achieved by reversely introducing microfluidics with surface tension differences, where the one with low surface tension undergoes the wetting transition. In addition, a generalized Navier boundary condition (GNBC)-based model of capillary displacement dynamics is developed within the framework of diffusive interface theory to investigate the MCL dynamics in the wetting transition regime. The oscillation-relaxation process is experienced for phase interface and microscopic dynamic contact angle θd in the wetting transition regime. Spontaneous filling distance follows dfill*∼t1/2, and reaching quasi-static stage follows dfill*∼t1. The previously neglected mechanism of inertial-viscous competition dominates the early dynamics of such dynamic wetting transition processes. θd∝ucl is observed to be valid solely under conditions where viscosity dominates, but it breaks down in the presence of dominant inertial effects. An escalation in slip substantially diminishes the influence of inertia, with frictional dissipation mediated by slip emerging as the predominant factor in the capillary-driven early dynamics. The origin of uncompensated Young's stress in the GNBC and its correlation with capillary forces is unified, unveiling the underlying physical mechanism governing the dynamics at the MCL. Finally, by decoupling the analysis of viscosity and slip, a new θd-viscous-slip formulation is proposed, in agreement with the model predictions.
The effect of collar weight and capture frequency on bodyweight in feral cats (Felis catus)
Authors: Ryan-Schofield Ned L. , Moseby Katherine E. , McWhorter Todd J. , Legge Sarah M. , McGregor Hugh W.
Published: May 2024

Context Animal-borne devices can affect animal survival, reproduction, and behaviour through both the addition of weight and bulk and the direct effects of initial and subsequent capture. Researchers commonly employ a general rule of thumb that weight of the device must be less than 5% of bodyweight for terrestrial animals; however, this threshold has little empirical basis. Aims We evaluated the effects of environmental variables, repeated capture, and weight of animal-borne devices on bodyweight in free-ranging feral cats. Methods We recaptured feral cats at varying frequencies, wearing GPS and/or VHF collars that ranged from 0.29% to 4.88% of bodyweight, and recorded change in cat weight over time. Key results Collar weight as a percentage of bodyweight was not a significant predictor of feral cat weight change. Rather, change in bodyweight was best described by a negative relationship with an increasing temperature and number of captures, and a positive relationship with time since collar attachment. Conclusions Capture had a significant influence on feral cat weight but collar weights up to 5% of bodyweight did not significantly contribute to weight loss. However, the absence of control cats without collars hindered definitive conclusions on the effect of collar weight on cat weight change. Implications Researchers should space capture and handling events more than 30 days apart to reduce effects of weight loss from capture and handling. Researchers should also consider increasing collar weight and reducing frequency of capture (where collars are less than 5% of bodyweight), particularly if cat bodyweight is a parameter of interest.
Data-driven estimation of battery state-of-health with formation features
Authors: He Weilin , Li Dingquan , Sun Zhongxian , Wang Chenyang , Tang Shihai , Chen Jing , Geng Xin , Wang Hailong , Liu Zhimeng , Hu Linyu , Yang Dongchen , Tu Haiyan , Lin Yuanjing , He Xin
Published: May 2024

Accurately estimating the state-of-health (SOH) of a battery is crucial for ensuring battery safe and efficient operation. The lifetime of lithium-ion batteries (LIBs) starts from their manufacture, and the performance of LIBs in the service period is highly related to the formation conditions in the factory. Here, we develop a deep transfer ensemble learning framework with two constructive layers to estimate battery SOH. The primary approach involves a combination of base models, a convolutional neural network to combine electrical features with spatial relationships of thermal and mechanical features from formation to subsequent cycles, and long short-term memory to extract temporal dependencies during cycling. Gaussian process regression (GPR) then handles SOH prediction based on this integrated model. The validation results demonstrate highly accurate capacity estimation, with a lowest root-mean-square error (RMSE) of 1.662% and a mean RMSE of 2.512%. Characterization on retired cells reveals the correlation between embedded formation features and their impact on the structural, morphological, and valence states evolution of electrode material, enabling reliable prediction with the corresponding interplay mechanism. Our work highlights the value of deep learning with comprehensive analysis through the relevant features, and provides guidance for optimizing battery management.
Unveiling the pathways of ethanol decomposition to carbon radicals by nanosecond pulse bubble discharge in liquid: a two-step hybrid model
Authors: Li Yuan , Shi Yaxuan , Wang Luning , Yuan Lei , Wang Yazhen , Zhang Guanjun
Published: May 2024

In recent years, bubble discharge in liquid has become a novel approach for the synthesis of carbon nanomaterials; however, the fundamental discharge process and synthesis mechanism are still not well understood. In this work, we build a two-step simulation model (combining 2D fluid dynamics and zero-dimensional plasma kinetics) to investigate nanosecond pulse discharge in an Ar bubble immersed in liquid ethanol and chemical reaction processes inside. The 2D simulation results show that discharge develops along the gas‒liquid interface where ethanol decomposes, resulting in much higher densities of active species (CH3, C2H5 and OH). The electric field of the selected reference point near the interface obtained by the 2D model is transmitted into the 0D model. The numerical results show that the decomposition of ethanol mainly occurs at the discharge stage, in which electron impact dissociation (e.g. C2H5OH + e → CH2OH + CH3 + e) and Penning dissociation (e.g. C2H5OH + Ar* → CH2OH + CH3 + Ar) dominate. The density of all carbonaceous species rapidly increases during discharge, while that of some carbon radicals (CH and C) continues to increase due to neutral species reactions when discharge ceases. By quantitative analysis of the reaction contributions, the dominant pathways of C2, CH and C are revealed, i.e. C2H5OH → C2H5 → [C2H, C2H2, C2H3] → C2 and C2H5OH → CH3 → CH2 → CH → C. In addition, the formation pathways of H and OH radicals, which are indispensable for the transformation of carbonaceous intermediates, are also analysed.
Quantifying reaction rates in methane oxidation: atomistic simulations at high temperature
Authors: Mao Yijin , Zhang Yuwen
Published: May 2024

This study presents a comprehensive analysis of methane oxidation at high temperatures (2500 K–3500 K)—a critical process in atmospheric chemistry and energy production. Employing reactive molecular dynamics simulations, the research bridges the knowledge gap in understanding the complex reaction networks at these elevated temperatures. Key features include the identification of intermediate species and the simplification of the reaction networks through advanced simulation and post-processing techniques. Another focus of the study is on employing the Arrhenius equation for nonlinear curve fitting to determine activation energy and pre-exponential factors for various reactions. The analysis reveals that, despite temperature variations, there are 121 common reactions among the reduced reaction systems. This discovery revealed the underlying consistency in methane oxidation pathways across a range of high temperatures. The results of this research are vital for enhancing current models of methane oxidation, particularly in the context of improving combustion processes and deepening our understanding of atmospheric dynamics involving methane.
Directional growth of iron oxide nanowires on a vicinal copper surface
Authors: Andrzejewska Weronika , Wojciechowski Paweł , Dobrotvorska Mariya V , Murawka Szymon , Sobieszczyk Paweł , Zelent Mateusz , Lewandowski Mikołaj
Published: May 2024

Single-crystal magnetic nanostructures with well-defined shapes attract lots of interest due to their potential applications in magnetic and spintronic devices. However, development of methods allowing controlling their mutual crystallographic and geometric orientation constitutes a significant scientific challenge. One of the routes for obtaining such structures is to grow the materials epitaxially on naturally-structured supports, such as vicinal surfaces of single-crystal substrates. Iron oxides are among the most well-known magnetic materials which, depending on the phase, may exhibit ferro/ferri- or antiferromagnetic ordering. We have grown iron oxide nanowires on a Cu(410) single-crystal substrate faceted with molecular oxygen. Scanning tunneling microscopy and low energy electron diffraction revealed that the oxide grows in the [111] direction, along the step edges of the substrate and rotated by ±15° with respect to the [010] direction of copper atomic terraces (so that the the growing elongated structures are orientated parallel to each other). Notably, x-ray photoelectron spectroscopy confirmed that the nanowires represent the ferrimagnetic γ-Fe2O3 (maghemite) iron oxide phase, while micromagnetic simulations indicated that the wires are single-domain, with the easy magnetization axis orientated in-plane and along the long axis of the wire.
Phase- and temperature-driven chiral topological superfluids on a honeycomb lattice
Authors: Li Tong , Li Ning , Guo Miaodi , Wu Ya-Jie
Published: May 2024

The correlated spinful Haldane model exhibits rich topological phases consisting of chiral topological superfluids (TSFs) and topological spin density waves. However, most of previous studies mainly focus on the case with the fixed hopping phase or at zero temperature. In this paper, we study the attractive spinful Haldane model with arbitrary phase at finite temperature. The chiral TSFs with Chern number C = 2 and 4 emerge driven by the phase and temperature. In particular, the temperature can drive a C = 2 topological superfluid from a trivial normal insulator phase at an appropriate interaction. The bulk topology of all TSFs is uncovered by the Wilson loop method, and confirmed by the responses of edge dislocations.
Quantum transport in InSb quantum well devices: progress and perspective
Authors: Lei Zijin , Cheah Erik , Schott Rüdiger , Lehner Christian A , Zeitler Uli , Wegscheider Werner , Ihn Thomas , Ensslin Klaus
Published: May 2024

InSb, a narrow-band III–V semiconductor, is known for its small bandgap, small electron effective mass, high electron mobility, large effective g-factor, and strong spin-orbit interactions. These unique properties make InSb interesting for both industrial applications and quantum information processing. In this paper, we provide a review of recent progress in quantum transport research on InSb quantum well devices. With advancements in the growth of high-quality heterostructures and micro/nano fabrication, quantum transport experiments have been conducted on low-dimensional systems based on InSb quantum wells. Furthermore, ambipolar operations have been achieved in undoped InSb quantum wells, allowing for a systematic study of the band structure and quantum properties of p-type narrow-band semiconductors. Additionally, we introduce the latest research on InAsSb quantum wells as a continuation of exploring physics in semiconductors with even narrower bandgaps.
Ultralow lattice thermal conductivity in type-I Dirac MBene TiB2
Authors: Sharma Ashish , Rangra Vir Singh
Published: May 2024

MBenes, the emergent novel two-dimensional family of transition metal borides have recently attracted remarkable attention. Transport studies of such two-dimensional structures are very rare and are of sparking interest. In this paper Using Boltzmann transport theory with ab-initio inputs from density functional theory, we examined the transport in TiB2 MBene system, which is highly dependent on number of layers. We have shown that the addition of an extra layer (as in bilayer BL) destroys the formation of type-I Dirac state by introducing the positional change and tilt to the Dirac cones, thereby imparting the type-II Weyl metallic character in contrast to Dirac-semimetallic character in monolayer ML. Such non-trivial electronic ordering significantly impacts the transport behavior. We further show that the anisotropic room temperature lattice thermal conductivity κ

L
for ML (BL) is observed to be 0.41 (0.52) and 2.00 (2.04) W m−1 K−1 for x and y directions, respectively, while the high temperature κ

L
(ML 0.13 W m−1 K−1 and BL 0.21 W m−1 K−1 at 900 K in x direction) achieves ultralow values. Our analysis reveals that such values are attributed to enhanced anharmonic phonon scattering, enhanced weighted phase space and co-existence of electronic and phononic Dirac states. We have further calculated the electronic transport coefficients for TiB2 MBene, where the layer dependent competing behavior is observed at lower temperatures. Our results further unravels the layer dependent thermoelectric performance, where ML is shown to have promising room-temperature thermoelectric figure of merit (ZT) as 1.71 compared to 0.38 for BL.
A new method of noise reduction grounded on the Hankel matrix and its application in rubbing fault diagnosis
Authors: Zhang Yi , Yu Mingyue , Feng Zhigang , Ma Ziru
Published: May 2024

In processing signals with singular value decomposition (SVD), one of the keys lies in building an appropriate Hankel matrix from signals. To address the difficulty in extracting the feature information of rubbing faults between rotor and stator, by taking advantage of the nature of rubbing fault information closely related to the rotation period of equipment, a new method of SVD is presented based on the Hankel matrix built from the periodicity of a rotation machine. First, with the periodicity of the rub-impact fault as the basis, the interval step size between Hankel vectors was determined to self-adaptively build a Hankel matrix of signals. Second, the newly-built Hankel matrix was denoised through the singular value differential spectrum. Third, to reduce the loss of data as much as possible, a strategy was proposed to rebuild signals according to the first and last rows of denoised signals. Fourth, features of rubbing faults were extracted according to the frequency spectrum of reconstructed signals, and faults were identified. To verify the applicability and effectiveness of the presented algorithm, various types of simulation signals and tester signals from different states were incorporated. Meanwhile, the presented algorithm was compared with a variety of classical methods. The results prove that the proposed method can not only effectively constrain noise interference, but also highlight fault feature information and correctly identify rub-impact faults.
Micro-scale study of microcapsule cracking performance based on XFEM and fluid cavity model
Authors: Wang Ruotong , Fan Yaqiong , Huang Huiyang , Huang Hua
Published: May 2024

Microcapsule self-healing has become popular for microcrack repairing in resin mineral composites, and the cracking performance of microcapsule directly affect their repair efficiency on the matrix material. In this study, the problem of how the volume of microcapsule core affects the cracking performance of microcapsule is addressed. Based on the extended finite element method, the representative volume element (RVE) considering the volume of microcapsule core is established by combining the cohesive zone model and the fluid cavity model. On this basis, a numerical simulation study of the cracking performance of RVE with different volumes of microcapsule core under dynamic loading is conducted to investigate the triggered cracking process of the fully filled and incompletely filled microcapsules besides their cracking behavior, respectively. This study provides a reference for the preparation of microcapsules and the numerical simulation of microcapsule mechanical properties.
High-quality lateral monolayer-multilayer graphene junction formed by selective laser thinning for self-powered photodetection
Authors: Tang Weijia , Zhu Xiaowen , Huang Jiaxin , Wu Su , Song QiYang , Zhang Butian , Zhang Zemin , Zhang Youwei , Wang Shun
Published: May 2024

The formation of an asymmetric junction is key to graphene-based photodetectors of high-sensitive photodetectability, because such a junction can not only facilitate the diffusion or drift of photogenerated carriers but also realize a self-powered operation. Here, a monolayer-multilayer graphene junction photodetector is accomplished by selectively thinning part of a multilayer graphene to a high-quality monolayer. Benefiting from the large photoabsorption cross section of multilayer graphene and strong asymmetry caused by the significant differences in optoelectronic properties between monolayer and multilayer graphene, the monolayer-multilayer graphene junction shows a 7-fold increase in short-circuit photocurrent as compared with that at the monolayer graphene-metal contact in scanning photocurrent images. The asymmetric configuration also enables the photodetector to work at zero bias with minimized dark current noise and stand-by power consumption. Under global illumination with visible light, a photoswitching ratio of 3.4 × 103, a responsivity of 8.8 mA W−1, a specific detectivity of 1.3 × 108 Jones and a response time of 11 ns can be obtained, suggesting a promising photoresponse. Moreover, it is worth mentioning that such a performance enhancement is achieved without compromising the broadband spectral response of graphene photodetector and it is hence applicable for long wavelength spectral range including infrared and terahertz.
Single-step, in-situ fabrication of flower-like NiCuMn hybrid oxyhydroxide electrodes for enhanced supercapacitor performance
Authors: Kumar Arunesh , Thomas Arpit , Arora Harpreet Singh
Published: May 2024

The rational design of highly active and low-cost electrode material is very promising for energy storage applications. The development of supercapacitors with high energy/power density is an imperative and challenging research objective. Herein, we report a highly facile synthesis approach for developing unique nano-porous hybrid NiCuMn oxyhydroxide architecture with remarkable electrochemical energy storage characteristics. The process involves dealloying of Ni15Cu15Mn70 alloy in an oxygen rich environment, resulting in a uniform 3-dimensional flower like morphology. The dealloyed electrode demonstrates ultra-high specific capacitance of 4110 F cm−3 at a high current density of 20 mA cm−2. A symmetric device exhibits a high volumetric capacitance of 365 F cm−3 at a current density of 10 mA cm−2 with a large potential window of 1.7 V. Even at very high-power density of 850 W l−1, the device exhibits a high energy density of 146 Wh l−1 along with remarkable cyclic stability of 95.4% after 10 000 cycles. The superior performance of nano-porous hybrid NiCuMn oxyhydroxide architecture was attributed to its unique microstructure that provides high surface area, and marginal internal resistance ensuring rapid charge transport.
Optimization of array encoding for ultrasound imaging
Authors: Spainhour Jacob , Smart Korben , Becker Stephen , Bottenus Nick
Published: May 2024

Objective. The transmit encoding model for synthetic aperture imaging is a robust and flexible framework for understanding the effects of acoustic transmission on ultrasound image reconstruction. Our objective is to use machine learning (ML) to construct scanning sequences, parameterized by time delays and apodization weights, that produce high-quality B-mode images. Approach. We use a custom ML model in PyTorch with simulated RF data from Field II to probe the space of possible encoding sequences for those that minimize a loss function that describes image quality. This approach is made computationally feasible by a novel formulation of the derivative for delay-and-sum beamforming. Main results. When trained for a specified experimental setting (imaging domain, hardware restrictions, etc), our ML model produces optimized encoding sequences that, when deployed in the REFoCUS imaging framework, improve a number of standard quality metrics over conventional sequences including resolution, field of view, and contrast. We demonstrate these results experimentally on both wire targets and a tissue-mimicking phantom. Significance. This work demonstrates that the set of commonly used encoding schemes represent only a narrow subset of those available. Additionally, it demonstrates the value for ML tasks in synthetic transmit aperture imaging to consider the beamformer within the model, instead of purely as a post-processing step.
Deciphering oxygen distribution and hypoxia profiles in the tumor microenvironment: a data-driven mechanistic modeling approach
Authors: Kumar P , Lacroix M , Dupré P , Arslan J , Fenou L , Orsetti B , Le Cam L , Racoceanu D , Radulescu O
Published: May 2024

Objective. The distribution of hypoxia within tissues plays a critical role in tumor diagnosis and prognosis. Recognizing the significance of tumor oxygenation and hypoxia gradients, we introduce mathematical frameworks grounded in mechanistic modeling approaches for their quantitative assessment within a tumor microenvironment. By utilizing known blood vasculature, we aim to predict hypoxia levels across different tumor types. Approach. Our approach offers a computational method to measure and predict hypoxia using known blood vasculature. By formulating a reaction-diffusion model for oxygen distribution, we derive the corresponding hypoxia profile. Main results. The framework successfully replicates observed inter- and intra-tumor heterogeneity in experimentally obtained hypoxia profiles across various tumor types (breast, ovarian, pancreatic). Additionally, we propose a data-driven method to deduce partial differential equation models with spatially dependent parameters, which allows us to comprehend the variability of hypoxia profiles within tissues. The versatility of our framework lies in capturing diverse and dynamic behaviors of tumor oxygenation, as well as categorizing states of vascularization based on the dynamics of oxygen molecules, as identified by the model parameters. Significance. The proposed data-informed mechanistic method quantitatively assesses hypoxia in the tumor microenvironment by integrating diverse histopathological data and making predictions across different types of data. The framework provides valuable insights from both modeling and biological perspectives, advancing our comprehension of spatio-temporal dynamics of tumor oxygenation.
A fused LASSO operator for fast 3D magnetic particle imaging reconstruction
Authors: He Jie , Li Yimeng , Zhang Peng , Hui Hui , Tian Jie
Published: May 2024

Objective. Magnetic particle imaging (MPI) is a promising imaging modality that leverages the nonlinear magnetization behavior of superparamagnetic iron oxide nanoparticles to determine their concentration distribution. Previous optimization models with multiple regularization terms have been proposed to achieve high-quality MPI reconstruction, but these models often result in increased computational burden, particularly for dense gridding 3D fields of view. In order to achieve faster reconstruction speeds without compromising reconstruction quality, we have developed a novel fused LASSO operator, total sum-difference (TSD), which effectively captures the sparse and smooth priors of MPI images. Methods. Through an analysis-synthesis equivalence strategy and a constraint smoothing strategy, the TSD regularized model was solved using the fast iterative soft-thresholding algorithm (FISTA). The resulting reconstruction method, TSD-FISTA, boasts low computational complexity and quadratic convergence rate over iterations. Results. Experimental results demonstrated that TSD-FISTA required only 10% and 37% of the time to achieve comparable or superior reconstruction quality compared to commonly used fused LASSO-based alternating direction method of multipliers and Tikhonov-based algebraic reconstruction techniques, respectively. Significance. TSD-FISTA shows promise for enabling real-time 3D MPI reconstruction at high frame rates for large fields of view.