bluuebunny/crossref_metadata_2025 huggingface dataset:
Fokker–Planck modeling of the stochastic dynamics of a Rijke tube
Authors: Lee Minwoo , Gupta Vikrant , Li Larry K. B.
Published: August 2024

We derive and numerically validate a low-order oscillator model to capture the stochastic dynamics of a prototypical thermoacoustic system (a Rijke tube) undergoing a subcritical Hopf bifurcation in the presence of additive noise. We find that on the fixed-point branch before the bifurcation, the system is dominated by the first duct mode, and the Fokker–Planck solution for the first Galerkin mode can adequately predict the stochastic dynamics of the overall system. We also find that this analytical framework predicts well the dominant mode on the limit-cycle branch, but underperforms in the hysteretic bistable zone where the role of nonlinearities is more pronounced. Besides offering new insights into stochastic thermoacoustic behavior, this study shows that an analytical framework based on the Fokker–Planck equation can facilitate the early detection of thermoacoustic instabilities in a Rijke-tube model subjected to noise.
Approximation of translation invariant Koopman operators for coupled non-linear systems
Authors: Hochrainer Thomas , Kar Gurudas
Published: August 2024

Many physical systems exhibit translational invariance, meaning that the underlying physical laws are independent of the position in space. Data driven approximations of the infinite dimensional but linear Koopman operator of non-linear dynamical systems need to be physically informed in order to respect such physical symmetries. In the current work, we introduce a translation invariant extended dynamic mode decomposition (tieDMD) for coupled non-linear systems on periodic domains. This is achieved by exploiting a block-diagonal structure of the Koopman operator in Fourier space. Variants of tieDMD are applied to data obtained on one-dimensional periodic domains from the non-linear phase-diffusion equation, the Burgers equation, the Korteweg–de Vries equation, and a coupled FitzHugh–Nagumo system of partial differential equations. The reconstruction capability of tieDMD is compared to existing linear and non-linear variants of the dynamic mode decomposition applied to the same data. For the regarded data, tieDMD consistently shows superior capabilities in data reconstruction.
Single-pixel-based hyperspectral microscopy
Authors: Uguen Lisa , Piedevache Ronan , Russias Gaspard , Helmer Sofian , Tregoat Denis , Perrin Stephane
Published: August 2024

Hyperspectral imaging allows to collect both spatial and quasi-continuous spectral information of an object. This work shows the innovative combination of single-pixel microscopy with hyperspectral imaging. An affordable hyperspectral microscope is able to observe micrometer-scale features of inorganic and biological samples and to reconstruct their spectral distribution with a high accuracy (i.e., a spatial and a spectral resolution of 9.0 μm and of 2.1 nm in the visible range, respectively). Furthermore, a statistical algorithm enables the identification of spectral responses of the targeted features as well as their classification.
i-PI 3.0: A flexible and efficient framework for advanced atomistic simulations
Authors: Litman Yair , Kapil Venkat , Feldman Yotam M. Y. , Tisi Davide , Begušić Tomislav , Fidanyan Karen , Fraux Guillaume , Higer Jacob , Kellner Matthias , Li Tao E. , Pós Eszter S. , Stocco Elia , Trenins George , Hirshberg Barak , Rossi Mariana , Ceriotti Michele
Published: August 2024

Atomic-scale simulations have progressed tremendously over the past decade, largely thanks to the availability of machine-learning interatomic potentials. These potentials combine the accuracy of electronic structure calculations with the ability to reach extensive length and time scales. The i-PI package facilitates integrating the latest developments in this field with advanced modeling techniques thanks to a modular software architecture based on inter-process communication through a socket interface. The choice of Python for implementation facilitates rapid prototyping but can add computational overhead. In this new release, we carefully benchmarked and optimized i-PI for several common simulation scenarios, making such overhead negligible when i-PI is used to model systems up to tens of thousands of atoms using widely adopted machine learning interatomic potentials, such as Behler–Parinello, DeePMD, and MACE neural networks. We also present the implementation of several new features, including an efficient algorithm to model bosonic and fermionic exchange, a framework for uncertainty quantification to be used in conjunction with machine-learning potentials, a communication infrastructure that allows for deeper integration with electronic-driven simulations, and an approach to simulate coupled photon-nuclear dynamics in optical or plasmonic cavities.
Ellingham diagrams of binary oxides
Authors: Shang Shun-Li , Lin Shuang , Gao Michael C. , Schlom Darrell G. , Liu Zi-Kui
Published: August 2024

Controlling the oxidation state of constituents by tuning the oxidizing environment and materials chemistry is vital to the successful synthesis of targeted binary or multicomponent oxides. We have conducted a comprehensive thermodynamic analysis of 137 binary oxides to calculate their Ellingham diagrams. It is found that the “reactive” elements that oxidize easily are the f-block elements (lanthanides and actinides), elements in groups II, III, and IV (alkaline earth, Sc, Y, Ti, Zr, and Hf), and Al and Li. In contrast, the “noble” elements are easily reduced. These are coinage metals (Cu, Ag, and especially Au), Pt-group elements, and Hg and Se. Machine learning-based sequential feature selection indicates that the ease of oxidation can be represented by the electronic structures of pure elements, for example, their d- and s-valence electrons, Mendeleev numbers, and groups, making the Periodic Table a useful tool for qualitatively assessing the ease of oxidation. The other elemental features that weakly correlate with the ease of oxidation are thermochemical properties such as melting points and the standard entropy at 298 K of pure elements. Applying Ellingham diagrams enables the oxidation of multicomponent materials to be predicted, such as the Fe–20Cr–20Ni alloy (in wt. %) and the equimolar high entropy alloy of AlCoCrFeNi. These Ellingham diagram-based predictions are in accordance with thermodynamic calculations using the CALPHAD approach and experimental observations in the literature.
Locomotion and strike damage of fish passing through a fish friendly tubular pump using computational fluid dynamics and discrete element coupling method
Authors: Pan Qiang , Zou Weihu , Zhang Desheng , Shi Weidong , van Esch B. P. M.
Published: August 2024

The tubular pump is a typical water transfer apparatus designed for extremely low heads and large flow rates. It serves as the core equipment in pumping stations situated at lakes, rivers, and canals. An adverse effect on the ecological environment stems from fish injury and mortality primarily caused by blade strikes. The present work combines computational fluid dynamics and the discrete element method to simulate the dynamics of fish passing through a simplified blade, allowing us to establish a safe margin of the strike force to further assess fish damage in a more complex tubular pump system. The results indicated that strikes on fish alter their motion state in terms of direction and magnitude, inducing chaotic movements that heighten the risk of subsequent strikes with downstream components. Fish tend to align their velocities with the surrounding fluid due to flow-induced drag after multiple contacts with solid structures. The knife-shaped leading edge, and particularly the blade tip side, emerged as the primary factor in creating strike damage, and the adoption of a slanted and blunt leading edge can effectively reduce fish damage. In addition, decreasing the shaft speed, increasing the flow rate, and restricting the fish size were identified as measures conducive to fish survival in running pumps. The study further suggested that using fewer but larger pumps operating at lower shaft speeds would contribute to better fish friendliness, which can also ensure a sufficient delivery head and mass flow rate.
A dimensionless heat transfer coefficient for free convection that is more appropriate than Nusselt number
Authors: Arakeri Jaywant H. , Kumar Navneet , Mahapatra Omshree
Published: August 2024

Heat transfer in flows created by buoyancy, or natural convection, is a widely studied topic across various disciplines spanning natural flows as well as those with engineering applications. The convective heat transfer rate on a surface is commonly represented by the Nusselt number (Nu), a ratio of convective to diffusive transport, expressed often as RanPrm, where Ra is the Rayleigh number, the buoyancy forcing parameter, and Pr the Prandtl number. Motivated by the observation that n∼1/3 for turbulent convection, which implies the heat flux is independent of the length scale (L, characteristic length related to the geometry), we propose an alternate and physically more meaningful non-dimensional heat transfer parameter, denoted by Cq. Cq is derived using only the near wall variables and does not contain L. For n=1/3, Cq is constant. Even for laminar convection, where n∼1/4, Cq∼Ra−1/12, a weak function of Ra. We show that for natural convection over several geometries and a wide range of Ra, the Cq values within a narrow range while the corresponding Nu values span several orders of magnitude. We also show that Cq is akin to the non-dimensional representation of wall shear stress, skin friction coefficient Cf. We believe that just like Cf, Cq will be an equally useful non-dimensional measure of heat transfer in natural convection flows.
Thermodynamics and simulation of 3D crystals and phase transitions under external fields
Authors: Ustinov E. A.
Published: August 2024

A field-supported multiphase kinetic Monte Carlo method previously applied to self-assembled trimesic acid molecular layers [Ustinov et al., Phys. Chem. Chem. Phys. 24, 26111 (2022)] was generalized to three-dimensional gas–liquid and gas–solid systems. This method allows us to calculate the thermodynamic potentials of the liquid and solid phases and then determine the parameters of the liquid–solid phase transition. In this study, the requirement that the gas phase be ideal was introduced as an additional condition. It was shown that in a two-phase system, the sum of the analytical expression for the chemical potential of an ideal gas and the external potential imposed on the gas phase exactly equals the chemical potential of the equilibrium crystal or liquid phase. For example, the coexistence of crystalline/liquid krypton and ideal gas has been considered. A comparison with previously published data has shown that the proposed approach provides the most accurate results for determining the parameters of phase transitions and fully satisfies the Gibbs–Duhem equation. This method does not impose any restrictions on the complexity or hardness of dense phases.
Constrained motion of self-propelling eccentric disks linked by a spring
Authors: Xu Tian-liang , Qin Chao-ran , Tang Bin , Gao Jin-cheng , Zhou Jiankang , Chen Kang , Zhang Tian Hui , Tian Wen-de
Published: August 2024

It has been supposed that the interplay of elasticity and activity plays a key role in triggering the non-equilibrium behaviors in biological systems. However, the experimental model system is missing to investigate the spatiotemporally dynamical phenomena. Here, a model system of an active chain, where active eccentric-disks are linked by a spring, is designed to study the interplay of activity, elasticity, and friction. Individual active chain exhibits longitudinal and transverse motions; however, it starts to self-rotate when pinning one end and self-beat when clamping one end. In addition, our eccentric-disk model can qualitatively reproduce such behaviors and explain the unusual self-rotation of the first disk around its geometric center. Furthermore, the structure and dynamics of long chains were studied via simulations without steric interactions. It was found that a hairpin conformation emerges in free motion, while in the constrained motions, the rotational and beating frequencies scale with the flexure number (the ratio of self-propelling force to bending rigidity), χ, as ∼(χ)4/3. Scaling analysis suggests that it results from the balance between activity and energy dissipation. Our findings show that topological constraints play a vital role in non-equilibrium synergy behaviors.
Localized stem structures in quasi-resonant two-soliton solutions for the asymmetric Nizhnik–Novikov–Veselov system
Authors: Yuan Feng , Rao Jiguang , He Jingsong , Cheng Yi
Published: August 2024

Elastic collisions of solitons generally have a finite phase shift. When the phase shift has a finitely large value, the two vertices of the (2 + 1)-dimensional two-soliton are significantly separated due to the phase shift, accompanied by the formation of a local structure connecting the two V-shaped solitons. We define this local structure as the stem structure. This study systematically investigates the localized stem structures between two solitons in the (2 + 1)-dimensional asymmetric Nizhnik–Novikov–Veselov system. These stem structures, arising from quasi-resonant collisions between the solitons, exhibit distinct features of spatial locality and temporal invariance. We explore two scenarios: one characterized by weakly quasi-resonant collisions (i.e. a12 ≈ 0), and the other by strongly quasi-resonant collisions (i.e. a12 ≈ +∞). Through mathematical analysis, we extract comprehensive insights into the trajectories, amplitudes, and velocities of the soliton arms. Furthermore, we discuss the characteristics of the stem structures, including their length and extreme points. Our findings shed new light on the interaction between solitons in the (2 + 1)-dimensional asymmetric Nizhnik–Novikov–Veselov system.
Nanocomposites of ferrocenyl-modified gold clusters and semiconducting polymers that integrate field-effect transistor and flash memory in a single neuromorphic device
Authors: Singh Deepa , Gunawardene Praveen N. , Workentin Mark S. , Fanchini Giovanni
Published: August 2024

We demonstrate that electroactive thin films incorporating semiconducting polymers and deterministic functionalized gold nanoclusters (ncAu25) lead to the integration of the functions of resistive memory device and field-effect transistor within a single component (“mem-transistor”) in a neuromorphic system. Memristor functions originate from ferrocenyl-modified gold nanoclusters (ncAu25-Fc) embedded in polymethyl-methacrylate (PMMA) and devices optimized for maximum 1/0 “flash” memory effect are found to contain 15 wt. % ncAu25-Fc. Integrated memristor and neuromorphic functions are obtained by replacing PMMA with poly(3-hexylthiophene) (P3HT) in the active layer, from which transistor effects are derived. Based on the energy band diagrams of ncAu25, PMMA, and P3HT, percolation theory is used to explain the memristor 1/0 on/off ratio as a function of ncAu25-Fc concentration. The use of ncAu25-Fc with charge-tunable, ferrocene-modified ligands is critical to achieve better cluster–polymer interfaces. Our work shows that nanostructures of polymers and metalorganic frameworks bear strong potential in the field of neuromorphic devices and circuital simplification of data storage technology.
Design of a low frequency, density profile reflectometer system for the MAST-U spherical tokamak
Authors: Rhodes T. L. , Peebles W. A. , Zeng Lei , Hall-Chen Valerian , Ronald Kevin , Kubota S. , Meng Yusong , Lantsov R. , Michael C. M. , Crocker N. A. , Scannell R.
Published: August 2024

Validated and accurate edge profiles (temperature, density, etc.) are vitally important to the Mega Ampere Spherical Tokamak Upgrade (MAST-U) divertor and confinement effort. Density profile reflectometry has the potential to significantly add to the measurement capabilities currently available on MAST-U (e.g., Thomson scattering and Langmuir probes). This work presents the diagnostic requirements, problems, and solutions facing profile reflectometry in spherical tokamaks and MAST-U in particular. Requirements include density measurements near zero electron density in the scrape off layer region, coverage for a broad range of MAST-U plasma parameters, high time (≤10 microseconds) and spatial resolutions (≤1 cm), reliability, and identification of the plasma start frequency.
Effect of distribution parameters on the noise spectrum of bubble clusters
Authors: Deng Fuqiang , Zhang Lingxin , Zhao Di , Li Yang
Published: August 2024

This study explores the effects of bubble distribution parameters on the noise spectrum of bubble clusters through direct numerical simulations across volume fractions from 0.005% to 40%. Three types of bubble cluster distributions were analyzed: layered (uniformly sized bubbles with layered positioning), random (uniformly sized bubbles with random positioning), and lognormal (log-normally distributed bubble sizes with random positioning). Using the Ffowcs Williams–Hawkings (FW–H) method, we evaluated the sound pressure levels of the clusters. We found that the arrangement of bubble positions has little impact on the collapse times of bubble clusters. At volume fractions greater than 0.5%, bubble size also shows minimal effect on collapse times. However, when the volume fraction is less than 0.5%, the collapse times gradually approach the collapse time of the largest bubble in the cluster in a free field. Noise spectrum analyses showed that the arrangement of bubble positions significantly influences the noise spectra within the volume fraction range of 0.5%–25%, but has minimal impact outside this range. Importantly, the distribution of bubble sizes shows negligible effects on the noise spectrum, demonstrated by the nearly identical sound pressure level octave decay rates for random and lognormal clusters at the same volume fractions. This consistency can be mathematically described by the fitting formula: decay rate (dB/octave) = 18.192 × α−0.047−16.264. These findings enhance our understanding of the noise spectrum across varied bubble cluster distributions and provide new insights into the mechanisms of cavitation noise.
A generalized van’t Hoff relation for the temperature dependence of complex-valued nonlinear spectra
Authors: Borkowski Ashley K. , Senanayake Hasini S. , Thompson Ward H.
Published: August 2024

The temperature dependence of spectra can reveal important insights into the structural and dynamical behavior of the system being probed. In the case of linear spectra, this has been exploited to investigate the thermodynamic driving forces governing the spectral response. Indeed, the temperature derivative of a spectrum can be used to obtain effective energetic and entropic profiles as a function of the measured frequency. The former can further be used to predict the temperature-dependent spectrum via a van’t Hoff relation. However, these approaches are not directly applicable to nonlinear, complex-valued spectra, such as vibrational sum-frequency generation (SFG) or two-dimensional infrared (2D-IR) photon echo spectra. Here, we show how the energetic and entropic driving forces governing such nonlinear spectra can be determined and used within a generalized van’t Hoff relation to predict their temperature dependence. The central idea is to allow the underlying energetic profiles to themselves be complex-valued. We illustrate this approach for 2D-IR spectra of water and SFG spectra of the air–water interface and demonstrate the accuracy of the generalized van’t Hoff relationship and its implications for the origin of temperature-dependent spectral changes.
Study on the influence of the fully enclosed barrier on the vortex-induced vibration performance of a long-span highway–railway double-deck truss bridge
Authors: Yang Yang , Li Long , Yao Gang , Wang Meng , Zhou Canwei , Lei Ting , Tan Hongbo
Published: August 2024

Long-span highway–railway double-deck truss bridges are mostly located in urban centers, where noise pollution and traffic safety issues have a great impact. The fully enclosed barrier has excellent sound insulation and windproof performance and has been widely used in double-deck truss bridges in recent years. However, the large volume and the low air permeability rate will affect the aerodynamic characteristics of the bridge, resulting in vortex-induced vibration (VIV). To analyze how the fully enclosed barrier influences the highway–railway bridge VIV performance, this study analyzes the Huangjuetuo Yangtze River Bridge, combined with the wind tunnel test and the numerical calculation method to study different variations of the static three-force coefficient, the change of VIV response, and its influence mechanism after setting the fully enclosed barrier. The results show that the static three-force coefficient of the double-deck truss bridge changes significantly, the drag coefficient increases, and the absolute values of the lift coefficient and the moment coefficient decrease after the fully enclosed barrier is set. The aerodynamic performance of the bridge is significantly reduced after the fully enclosed barrier is set, and the amplitude and range of the VIV response are increased. Vertical bending VIV increased by an average of 58.5%, and torsional VIV increased by an average of 21.9%. Considering driving comfort and safety, attention should be paid to the double-deck truss bridge with a fully enclosed barrier.
Effects of combined-type wind barriers on the aerodynamic characteristics of train–bridge system for a long-span suspension bridge
Authors: Liang Haobo , Zou Yunfeng , Zhang Yilin , Cai Chenzhi , He Xuhui
Published: August 2024

The development tendency of lightweight and higher-speed regarding trains goes against the safety and comfort requirement of high-speed trains, especially in the scenario of the train running on bridges within crosswind environments. Wind barriers have been proven to be an effective measure to guarantee the train's operation security. In this paper, a new type of wind barrier consisting of the fence-type wind barrier form and open hole-type wind barrier form has been proposed. Then, a series of wind tunnel tests about the large-scale section model of a large-span suspension bridge installed with different wind barriers have been conducted. The effects of three different forms of wind barrier including fence-type, open hole-type, and combined-type on the aerodynamic characteristics of the train-bridge system have been analyzed. The windproofing effectiveness and the protection mechanism of the combined-type wind barrier on the train-bridge system have been revealed through the measured aerodynamic characteristics. The results show that the installation of open hole-type, fence-type, and combined-type wind barriers at a height of 4 m and a ventilation rate of 19% yields a maximum reduction in the train drag coefficient of 67.70%, 72.92%, and 97.21%, respectively. Moreover, the combined-type wind barrier can improve the train-bridge system's aerodynamic performance and trains' running safety on bridges when comparing with the open hole-type and fence-type wind barriers. The proposed combined-type wind barrier can provide a more efficiency and practical way for the high-speed train's running safety on the bridge.
Investigation of flow over an inclination pile under a Reynolds number of 3900 by numerical simulation
Authors: Zhang Shicheng , Liu Mingming
Published: August 2024

Flow over an inclination pile was studied numerically by solving the Navier–Stokes equations with large eddy simulation closure under a Reynolds number of 3900, and the inclination angles were in the range of −45° ≤ θ ≤ 45°. First, flow over a finite-length vertical pile with symmetric boundary conditions at both the upper and lower boundaries is used for verification, and the results are in good agreement with the previous results. Then, the lower boundary is set as a no-slip wall to simulate a rigid seabed, and 19 different inclination angles are numerically simulated to investigate the effects of the rigid seabed on the hydrodynamic characteristics and the wake structure of the cylindrical wake with different inclination angles. It is found that there is a significant difference between the forces on the piles, which were inclined forward and backward due to the end boundary conditions. When the pile is inclined forward, the force on the pile and the frequency of vortex shedding are lower than that of a vertical pile, which is more conducive to the stability of the structure. When the pile is inclined backward, the lower sidewall induces a strong spiral upward flow of the fluid at the lower end around the pile, which leads to the shedding of the wake vortex at a very close position to the pile. The return zone tightening phenomenon occurs at inclination angles greater than 25° backward, and this phenomenon leads to a sharp increase in the forces on the pile. Backward inclination angles greater than 30° are extremely unfavorable for structural forces.
Optimization of submicron Ni/Au/Ge contacts to an AlGaAs/GaAs two-dimensional electron gas
Authors: Mann Matthew , Nakamura James , Liang Shuang , Maiti Tanmay , Diaz Rosa , Manfra Michael J.
Published: August 2024

We report on fabrication and performance of sub-micrometer Ni/Au/Ge contacts to a two-dimensional electron gas in an AlGaAs/GaAs heterostructure. Utilizing scanning transmission electron microscopy, energy dispersive x-ray spectroscopy, and low temperature electrical measurements, we investigate the relationship between contact performance and the mechanical and chemical properties of the annealed metal stack. Contact geometry and crystallographic orientation significantly impact performance. Our results indicate that the spatial distribution of germanium in the annealed contact plays a central role in the creation of high transmission contacts. We characterize the transmission of our contacts at high magnetic fields in the quantum Hall regime. Our work establishes that contacts with an area of 0.5 μm2 and resistance less than 400 Ω can be fabricated with high yield.
A new mechanical engineering strategy based on microsphere probe and its application in transition metal dichalcogenides
Authors: Yang Rui , Cui Yi , Yang Zicong , Qin Feng , Rao Junhao , Yuan Hongtao , Qiu Caiyu
Published: August 2024

Mechanical engineering of 2D materials allows continuous and reversible modulation of their electronic and photonic properties. Although photoluminescence (PL) measurement is an effective way to monitor the effects of mechanical forces on 2D semiconductors, there is currently a lack of techniques to enhance PL signals during stress application. This study presents an innovative mechanical engineering approach that integrates a dielectric microsphere as an atomic force microscopy (AFM) probe into a Raman-AFM system. Force–distance curve tests and COMSOL simulations were performed to analyze and estimate the compressive stress exerted by the microsphere. Importantly, the PL signals of transition metal dichalcogenides subjected to microsphere probe's force were enhanced and reveal distinct mechanical responses depending on the substrate rigidity: compressive pressures for rigid substrates and tensile strains for flexible ones. Notably, this strategy not only amplifies spectral signals in real time but also achieves fine stress modulation in the precise targeted material region, demonstrating its superiority in sensitive mechanical engineering applications. Our work offers a new avenue for the deliberate design of mechanical strains in 2D materials, which is crucial for optimizing the performance of related devices.
On-demand jetting of high-viscosity liquid by jet tube impact
Authors: Xue Boce , Zhang Yanzhen , Hu Guofang , Wu Yuyao , Li Zihao , He Weiwei , Li Runsheng
Published: August 2024

The on-demand jetting of high-viscosity liquid has significant applications in fields such as electronic packaging and bioprinting. Conventional methods for high-viscosity liquid jetting often employ a needle propelling the liquid rapidly, which demands high precision in the manufacturing and assembly of the needle and nozzle, and can potentially damage biomaterials. In this study, a novel method utilizing jet tube impact for on-demand high-viscosity liquid jetting is proposed, leveraging the inherent inertia of the liquid to generate the pressure pulse necessary for on-demand jetting. This method reduces the precision requirements for the device, enables device simplification, and avoids harm to biomaterials. The feasibility of this approach for on-demand high-viscosity liquid jetting is validated through experiments, and by combining numerical simulations, the jetting mechanism is revealed and primary factors influencing jetting performance are investigated. It is found that the water hammer pressure wave induced by the liquid inertia during the sudden velocity change of the jet tube is the predominant driving force for jetting, and the peak pressure can exceed 1 MPa and the peak jet velocity can exceed 15 m/s. An increase in the jet tube impact velocity and an extension of the acceleration duration at the same impact velocity both lead to an increase in the pressure wave amplitude. In addition, a decrease in the liquid level height shortens the period of the pressure wave. These factors all have an influence on the jetting performance. This study provides a new insight and theoretical foundation for the on-demand high-viscosity liquid jetting.
The past, present and future of molecular testing for Neisseria gonorrhoeae in Australia: still challenging
Authors: Pryce Todd M.
Published: August 2024

Nucleic-acid amplification tests (NAATs) for Neisseria gonorrhoeae, particularly earlier generation tests, have been beset with specificity problems associated with cross reaction with commensal neisseriae. This is a particular problem for extragenital samples such as pharyngeal swabs, which are loaded with commensal Neisseria species and also a common site of infection for N. gonorrhoeae. To address the specificity issues, supplementary testing (whereby samples testing positive in a screening NAAT are reflexively tested with a secondary NAAT) has been widely implemented, with associated guidelines in place in Australia since 2005. Unlike earlier generation tests, modern commercial N. gonorrhoeae NAATs are (for the most part) much improved in terms of sensitivity and specificity and some now include testing claims for oropharyngeal and anorectal sites. This has raised questions over the ongoing utility of N. gonorrhoeae supplemental testing (particularly for urogenital sites) and left supplemental testing needing to play ‘catch-up’ in terms of sensitivity compared to newer commercial NAATs. More recently, supplemental testing has found added clinical utility with the addition of antimicrobial resistance (AMR) markers. Here I present the current N. gonorrhoeae testing guidelines, recent improvements in N. gonorrhoeae NAATs, discuss the changing role of supplemental testing and future sexually transmitted infection (STI) testing needs.
Vulnerability in research ethics: A call for assessing vulnerability and implementing protections
Authors: Findley Michael G. , Ghosn Faten , Lowe Sara J.
Published: August 2024

Ethics standards reference the need for special consideration of vulnerable populations, such as pregnant women, incarcerated individuals, and minors. The concept of vulnerability is poorly conceptualized in the medical sciences where it originated, and its application to the social sciences is even more challenging. Social science researchers may unwittingly fail to appreciate preexisting vulnerabilities and indeed may be responsible for inducing new research-related vulnerability. In this paper, we present the first comprehensive coding of country-level vulnerability designations. Specifically, we coded all 355 official documents governing social/behavioral human subjects research for the 107 countries with such regulations and identified 68 distinct vulnerability categories. The data reveal substantial regional variation, overemphasis of categories derived from medical sciences, neglect of critical categories such as displacement, and likely heterogeneity within and across groups. The article provides a conceptual framework that shifts the problem away from static, enumerated categories toward emphasis on research-induced vulnerability. Based on our conceptualization and coding, we present a framework for assessing vulnerability and implementing appropriate protections.
New insights on the signature change via the Colombeau framework
Authors: Silva J A , Carvalho F C , Garcia A R G
Published: August 2024

In this paper we propose a reinterpretation of the Mansouri–Nozari signature-change approach to the early Universe, in which the metric signature only occurs for t < 0 within the Euclidean regime, posing a challenge in providing coherent physical interpretations in advance. We ensure that the sign change occurs for t > 0 in the Euclidean regime. Our findings show that the energy-momentum tensor does not vanish on the signature-changing surface, even when we adopt conditions commonly used in the literature. Furthermore, we formulate a modified cosmology within the framework of signature-changing and discuss the modifications that our approach introduces to the cosmological equations. We establish a constraint relating the equation of state parameter and its singular part and we determine an effective equation of state as function of the redshift. Finally, we show that the law of conservation of matter in the modified ΛCDM model remains valid.
Simultaneous effects of capillary number, viscosity ratio, and contraction ratio on droplet dynamics in contraction microchannel
Authors: Hoang Van Thanh , Nguyen Thanh Tung , Truong-Le Bich-Tram , Vo Tran Anh
Published: August 2024

In microfluidic systems utilized droplets, fluid properties, flow conditions, and channel geometry play crucial roles in the movement and manipulation of droplets. This study employs methods of theoretical modeling and three-dimensional numerical simulation to investigate droplet dynamics in a contraction microchannel under the simultaneous influence of different factors, such as capillary number (Ca), viscosity ratio (λ), and contraction ratio (C). Specifically, a theoretical model is introduced for predicting the transition of droplets from trap to squeeze, and it is observed to be

C

a
I

=
f

(

C
,

 

λ

)

. Meanwhile, droplet dynamics are investigated for the transition from squeeze to breakup for finding critical capillary number value (Ca
II
). In addition, the critical viscosity ratio for the process from squeeze to breakup has been figured out by numerical results for a wide range of contraction ratios. Eventually, droplet dynamics including deformation, velocity ratio, and breakup during contraction microchannel are also quantitatively studied under the factors above.
A heterogenous integrated neural recording system with elastocapillary self-assembled Au-PDMS-PEG neural probe and customized ASIC
Authors: Wang Gang , You Changhua , Yang Liu , Liu Daoyin , Zeng Huanhuan , Xue Ning , Yao Lei
Published: August 2024

This study presents the design and implementation of a heterogenous integrated neural recording system consisting of a flexible Au-PDMS-PEG probe and customized complementary metal oxide semiconductor (CMOS) application-specific integrated circuit (ASIC) in a standard 0.18 μm process. The flexible Au-PDMS-PEG probe was prepared by an elastocapillary self-assembled process, achieving an electrode impedance of 250 kΩ (@1 kHz). The customized CMOS ASIC contains 36 modular digital pixels (MDP). It achieves 5.69 μVrms input referred noise, 10.29 effective number of bits, 49.5 μW power consumption, and 0.092 mm2 area for a single MDP unit. Spontaneous spikes were also recorded in the mouse cortex, with a peak-to-peak amplitude of 389.2 μVPP and a signal-to-noise ratio of 19.36. Benchtop and in-vivo experiments were conducted to validate the functionality and performance of the proposed neural recording system.
Nucleic acid purification through nanoarchitectonics: magnetic bead integration with microfluidic chip technology
Authors: Priya P Ramya , Deepak K S , Dubey Satish Kumar , Goel Sanket
Published: August 2024

Purified DNA and Polymerase Chain Reaction (PCR) are crucial parts of molecular biology techniques in various fields such as genomics, forensics, and diagnostics. The proposed microfluidic device is used to perform several steps like the adsorption of DNA present in processed PCR onto bare magnetic beads, cleaning of contaminants with ethanol-diluted buffer reagent, and eluting the adsorbed DNA in an elution buffer, which is further used for downstream application. The entire sample purification is accomplished in about 25 min. A comparative analysis is conducted using a commercially available DNA purification kit. By employing the suggested microfluidic chip alongside the commercial kit, a commercial spectrophotometer is utilized to measure the purity. This is done by obtaining the A260/A280 ratio, which allows for the assessment of both the quantity and purity of the extracted DNA. The A260/A280 ratios for the spin column-based, magnetic stand-based, and microfluidic chip- based tests were 1.86, 1.98, and 1.74, respectively. The analysis of the eluted DNA findings indicated that the quality was suitable for future PCR amplification. Additionally, this microchip-based device has the potential to be utilized as a bedside device for DNA purification in point of care applications, with a purification time of 25 min.
Underwater surface discharge characteristics and multi-physical effects with conductive coating load under fast electric pulse
Authors: Han Ruoyu , Bai Jie , Yan Jiaqi , Wang Menglei , Yuan Wei , Qin Sichao , Wang Yanan
Published: August 2024

Underwater pulsed discharge, where intense reactions between ionized gas and condensed-state water exist, can be a joint problem of both physics and chemistry. The study tries to build a comprehensive visualization of nanosecond-risetime discharge initiated by a conductive coating and its successive multi-physical effects. The scenario is established via a pair of thin-plate electrodes positioned on both sides of the coating, and diagnosed using high-speed backlight photography synchronized with electrical and optical measurements. For the sprayed Cu/Ag composite coating, the current density can achieve 20 A mm−2 which is high enough to induce the surface ‘electrical explosion’ and breakup the conductive matrix within 500 ns. By increasing the discharge energy from 0.5 to 10 J, the explosion of coating can exhibit different discharge types as exploding wires. Adopting a thicker carbon foil or cermet sheet can reduce the current density and energy deposition rate, which converts the global explosion to partial ones, significantly increasing the lifetime. With the aid of the conductive coating, the breakdown delay diminishes, and hot plasma spots form in 100 ns due to non-uniform Joule heating of the pulsed current, which gradually evolve to a plasma bubble cluster above the lower-conductive coating (bypassing branch). Once the high-conductive plasma channel bridges two electrodes, it will be intensively heated (MW-level energy deposition rate) and rapidly expand, accompanied by underwater shock wave (102 kPa @30 cm) and bubble/cavity generation (20 mm maximum). Finally, microscopic characterization has been made, and the erosion morphology suggests typical arc erosion features (pits, cracks, etc) and nanoparticles condensation from evaporated materials.
Improving optical and electrical stabilities of fluorine-doped tin oxide films in sweat solutions with O2 addition in plasma
Authors: Yan Caibo , Su Zhiwei , Zhao Zhuo , Zhou Yanwen
Published: August 2024

Recently, the use of wearable smart devices has significantly increased; however, sweat can corrode the outer-layer films, thereby decreasing their transmittance, conductivity, and overall functionality. In this study, fluorine-doped tin oxide (FTO) films for wearable smart devices were prepared via magnetron sputtering. The effects and mechanism of O2 gas flow in plasma on the properties of the fabricated films were investigated. Minor changes were observed in the film morphologies, with the preferred orientations shifting from polar (101) to nonpolar (110) and standard positions. As the O2 flow rate increased from 0 to 2 sccm, the transmittance of the film within the visible spectrum increased from 83% to 89%, with sheet resistance values in the order of 102–106 Ω sq−1. Following immersion in an acidic sweat solution, the film without O2 peeled off, whereas several corrosion pits were observed in the films with 1 or 2 sccm O2. Conversely, following immersion in an alkaline sweat solution, several pits were observed in the films without O2, while the other films exhibited excellent corrosion resistance. The transmittance of the films immersed in different solutions did not significantly differ. Notably, the sheet resistances of the films treated with 1 sccm O2 met the industrial requirement of 3000 Ω. Moreover, the coexistence of polar and nonpolar planes provided transparency and conductive stability to the FTO films treated with 1 sccm O2. Our study aimed to not only enhance the transmittance and sweat-corrosion resistance but maintain the conductivity of the outer screen layer of a wearable smart electronic device.
Magnetization dynamics in skyrmions due to high-speed carrier injections from Dirac half-metals
Authors: Bhattacharjee Satadeep , Lee Seung-Cheol
Published: August 2024

Recent developments in the magnetization dynamics in spin textures, particularly skyrmions, offer promising new directions for magnetic storage technologies and spintronics. Skyrmions, characterized by their topological protection and efficient mobility at low current density, are increasingly recognized for their potential applications in next-generation logic and memory devices. This study investigates the dynamics of skyrmion magnetization, focusing on the manipulation of their topological states as a basis for bitwise data storage through a modified Landau–Lifshitz–Gilbert equation (LLG). We introduce spin-polarized electrons from a topological ferromagnet that induce an electric dipole moment that interacts with the electric gauge field within the skyrmion domain. This interaction creates an effective magnetic field that results in a torque that can dynamically change the topological state of the skyrmion. In particular, we show that these torques can selectively destroy and create skyrmions, effectively writing and erasing bits, highlighting the potential of using controlled electron injection for robust and scalable skyrmion-based data storage solutions.
Weak antilocalization in the topological semimetal candidate YbAuSb
Authors: Ram D , Banerjee S , Sundaresan A , Samal D , Hossain Z
Published: August 2024

We report a study of the magnetic and magnetotransport properties of YbAuSb single crystals, which were grown using the bismuth flux. The x-ray diffraction data indicate that YbAuSb crystallizes in LiGaGe-type hexagonal structure with space group P63
mc. Our magnetic measurements revealed that YbAuSb is nonmagnetic with a divalent state of ytterbium ion. The temperature-dependent electrical resistivity exhibits a metallic behavior. A cusp-like feature in transverse and longitudinal magnetoresistance is observed at the low field regime. This cusp-like feature is attributed to the weak antilocalization (WAL) effect, which is more prominent at low temperatures. The transverse magnetoconductivity in low field region follows semiclassical model

∼

B

, which is consistent with the presence of WAL phenomena. The WAL effect in transverse and longitudinal magnetoconductance is well explained using the modified Hikami–Larkin–Nagaoka and generalized Altshuler–Aronov model, respectively. The Hall resistivity shows a linear field dependence with a positive slope, suggesting hole charge carriers dominate in electrical transport. The calculated carrier density and mobility are in the order of 1020 cm−3 and 102 cm2 V−1 s−1, respectively.
A review of radiation doses and associated parameters in Western Australian mining operations (2020-23)
Authors: Ralph Martin I , Koshy Jubin , Foley Paul
Published: August 2024

Government policies have stimulated the Western Australian (WA) mining industry to position itself as a significant global supplier of critical minerals, including lithium and rare earths. In WA the lithology that supports these minerals is often associated with elevated concentrations of naturally occurring radioactive materials (NORMs) and the increase in the number of mining operations pursuing the minerals has witnessed a commensurate increase in the number of workers potentially exposed to the radiation emitted from the NORMs. The regulatory framework for radiation protection in WA mining operations underwent significant change with the implementation of the Work Health and Safety Act 2020 and Work Health and Safety (Mines) Regulations 2022 which both came into effect on the 31 of March 2022. Under the new framework mining operations identified as having workers who were likely to receive annual effective doses (EDs) from NORMS above one mSvy−1 are referenced as relevant mines (RM). RMs are required to submit an annual report of the estimates of EDs)received by their workforce to the mining regulatory authority (WorkSafe WA: Mines Safety). This research provides an overview of the new legislative framework and updates the information in Ralph and Cattani (2022 J. Radiol. Prot.
42 012501) to include data derived from annual occupational EDs submitted by RMs in the three-year period spanning 2020–21, 2021–22 and 2022–23. In 2022–23, 38 mining operations were identified as RMs, an increase of ten from 2021–22 which in turn had increased by six from the 2020–21 reporting period. The mean annual ED reported for the three-year period was 1.0 mSv, the level at which regulatory intervention should be considered. The maximum ED was 4.9 mSv, just below the threshold of 5 mSv above which exposed workers are considered Designated Workers and are subject to focused monitoring. The collective effective annual dose of the mine worker population reached an historical maximum of 2339 man mSv in 2022–23. Analysis of the three main exposure pathways confirms that inhalation of long-lived alpha emitting radionuclides in dust remains the most significant contributor to worker EDs. Inhalation of radon-222 and radon-220 and their short-lived progeny, once considered as a negligible contributor to worker annual EDs is the second most significant exposure pathway. A declining trend in the number of samples collected per worker is highlighted as requiring remediation to provide confidence in the reported annual EDs. The transition to the new legislative framework for radiation protection in mines has been supported by the publication of guidance materials which have been widely endorsed by the industry.