bluuebunny/crossref_metadata_2025 huggingface dataset:
Venus cloud discontinuity in 2022
Authors: Peralta J. , Cidadão A. , Morrone L. , Foster C. , Bullock M. , Young E. F. , Garate-Lopez I. , Sánchez-Lavega A. , Horinouchi T. , Imamura T. , Kardasis E. , Yamazaki A. , Watanabe S.
Published: February 2023

Context. First identified in 2016 by the Japan Aerospace eXploration Agency (JAXA) Akatsuki mission, the discontinuity or disruption is a recurrent wave observed to propagate over decades at the deeper clouds of Venus (47–56 km above the surface), while its absence at the top of the clouds (∼70 km) suggests that it dissipates at the upper clouds and contributes to the maintenance of the puzzling atmospheric superrotation of Venus through wave-mean flow interaction.

Aims. Taking advantage of the campaign of ground-based observations undertaken in coordination with the Akatsuki mission from December 2021 until July 2022, we undertook the longest uninterrupted monitoring of the cloud discontinuity to date to obtain a pioneering long-term characterisation of its main properties and to better constrain its recurrence and lifetime.

Methods. The dayside upper, middle, and nightside lower clouds were studied with images acquired by the Akatsuki Ultraviolet Imager (UVI), amateur observers, and SpeX at the NASA Infrared Telescope Facility (IRTF). Hundreds of images were inspected in search of the discontinuity events and to measure key properties such as its dimensions, orientation, and rotation period.

Results. We succeeded in tracking the discontinuity at the middle clouds during 109 days without interruption. The discontinuity exhibited properties nearly identical to measurements in 2016 and 2020, with an orientation of 91° ±8°, length of 4100 ± 800 km, width of 500 ± 100 km, and a rotation period of 5.11 ± 0.09 days. Ultraviolet images during 13–14 June 2022 suggest that the discontinuity may have manifested at the top of the clouds during ∼21 h as a result of an altitude change in the critical level for this wave, due to slower zonal winds.
Accounting for non-ideal mixing effects in the hydrogen-helium equation of state
Authors: Howard S. , Guillot T.
Published: February 2023

Context. The equation of state for hydrogen and helium is fundamental for studying stars and giant planets. It has been shown that because of interactions at atomic and molecular levels, the behaviour of a mixture of hydrogen and helium cannot be accurately represented by considering these elements separately.

Aims. This paper aims at providing a simple method to account for interactions between hydrogen and helium in interior and evolution models of giant planets.

Methods. Using on the one hand ab initio simulations that involve a system of interacting hydrogen and helium particles and pure equations of state for hydrogen and helium on the other, we derived the contributions in density and entropy of the interactions between hydrogen and helium particles.

Results. We show that relative variations of up to 15% in density and entropy arise when non-ideal mixing is accounted for. These non-ideal mixing effects must be considered in interior models of giant planets based on accurate gravity field measurements, particularly in the context of variations in the helium-to-hydrogen ratio. They also affect the mass-radius relation of exoplanets. We provide a table that contains the volume and entropy of mixing as a function of pressure and temperature. This table is to be combined with pure hydrogen and pure helium equations of state to obtain an equation of state that self-consistently includes mixing effects for any hydrogen and helium mixing ratio and may be used to model the interior structure and evolution of giant planets to brown dwarfs.

Conclusions. Non-linear mixing must be included in accurate calculations of the equations of state of hydrogen and helium. Uncertainties on the equation of state still exist, however. Ab initio calculations of the behaviour of the hydrogen-helium mixture in the megabar regime for various compositions should be performed in order to gain accuracy.
A horn-coupled millimetre-wave on-chip spectrometer based on lumped-element kinetic inductance detectors
Authors: Chowdhury U. , Levy-Bertrand F. , Calvo M. , Goupy J. , Monfardini A.
Published: February 2023

Context. Millimetre-wave astronomy is an important tool for both general astrophysics studies and cosmology. A large number of unidentified sources are being detected by the large field-of-view continuum instruments operating on large telescopes.

Aims. New smart focal planes are needed to bridge the gap between the large bandwidth continuum instruments operating on single-dish telescopes and high spectral and angular resolution interferometers (e.g. ALMA in Chile and NOEMA in France). The aim is to perform low to medium spectral resolution observations and select a lower number of potentially interesting sources (i.e. high-redshift galaxies) for further follow-up.

Methods. We have designed, fabricated, and tested an innovative on-chip spectrometer sensitive in the 85–110 GHz range. It contains 16 channels, each of which covers a frequency band of about 0.2 GHz. A conical horn antenna coupled to a slot in the ground plane collects the radiation and guides it to a millimetre-wave microstrip transmission line placed on the other side of the mono-crystalline substrate. The millimetre-wave line is coupled to a filter-bank spectrometer. Each filter is capacitively coupled to a lumped-element kinetic inductance detector (LEKID). The microstrip configuration provides the benefit of low loss, due to the mono-crystalline substrate, and protects the LEKIDs from illumination by stray un-filtered light.

Results. The prototype spectrometer exhibits a spectral resolution R = λ/Δλ ≈ 300. The optical noise equivalent power is in the low 10−16 W Hz−1/2 range for an incoming power of about 0.2 pW per channel. The device is polarisation-sensitive, with a cross-polarisation lower than 1% for the best channels.
Fault detection method of secondary sound source in ANC system based on impedance characteristics
Authors: DAI Hai , CHEN Kean , WANG Yang , YU Haoxin
Published: February 2023

As an indispensable component in an active noise control system, the working states of the secondary sound sources affect directly noise reduction and the robustness of the system. Therefore, it is very crucial to detect the working states of the secondary sound sources in the process of active control in real time. In this study, a real-time fault detection method for secondary sound sources during the process of active control is presented, and the corresponding detection algorithm is numerically given and experimentally verified. By collecting the input voltage and output current of the speaker unit, the sound quality factor is calculated to comprehensively judge the working state of the secondary sound sources. The simulation and experimental results show that the present method is simple and has low computational cost, can accurately reflect accurately the working states of the secondary sound sources in real time, and provides a basis for judging the operation of the active noise control system.
A dense obstacle avoidance algorithm for UAVs based on safe flight corridor
Authors: FAN Liyuan , ZHANG Haozhe , XU Zhao , LYU Mingwei , HU Jinwen , ZHAO Chunhui , LIU Xiaobin
Published: February 2023

Aiming at the problem of autonomous obstacle avoidance of fixed-wing UAVs in a complex, dense and multi-obstacle environment, a path planning algorithm for fixed-wing UAVs based on a safe flight corridor is proposed. The difficulty of avoiding dense obstacles lies in the choice of obstacle circumvention and traversal: although circumvention is safer, the flight cost is greater; although the traversal cost is lower, the safety threat is higher. How to quickly solve the optimal path is the core issue. This paper firstly defines a safe flight corridor innovatively based on the maneuvering characteristics of fixed-wing UAVs and the Dubins curves. By comprehensively considering UAV flight safety and flight costs, an obstacle threat evaluation function is constructed. Secondly, in view of the computational complexity caused by the dense obstacles, an obstacle clustering algorithm based on obstacle density is proposed, and the nonlinear evaluation function in a high dynamic environment is quickly approximated by Monte Carlo sampling method. Finally, simulations verify the effectiveness of the proposed algorithm in solving dense obstacle avoidance for fixed-wing UAVs.
Multi-target assignment hunting strategy of UAV swarm based on improved K-means algorithm and shortest time mechanism
Authors: HU Bin , ZHU Yahui , DU Zhize , ZHAO Zixin , ZHOU Yannian
Published: February 2023

Multi-target hunting of UAV swarm is an important tactical means. This paper proposes a hunting strategy based on improved K-means and the shortest time mechanism. The large-scale task assignment problem is complex in structure and difficult to solve. To obtain higher hunting efficiency and reduce the amount of calculation on the single UAV, the hybrid architecture is used to decompose the complex multi-target hunting problem into a set of tasks that the UAV need to perform, which reduces the coupling of the system and the complexity of problem. Firstly, the multi-target hunting problem is stratified by the improved K-means algorithm to form multiple independent single target hunting subsystems. In the subsystem, the single target hunting task is decomposed into multiple subtasks that are easy to be executed by UAVs, and a one-to-one matching relationship between subtasks and UAVs is established by using the shortest time mechanism. UAV swarm can achieve multi-target hunting only by executing subtasks. The simulation results show that the UAV swarm can effectively allocate the multi-target hunting problem, which proves the effectiveness of the allocation strategy is proved.
Dual high frequency square wave injection method for dual winding permanent magnet synchronous motor sensorless control
Authors: ZHOU Qixun , MA Ping'an , ZHOU Yong , HE Hucheng , CHANG Chongchong
Published: February 2023

针对高频方波注入法零低速下永磁同步电机无位置传感器控制存在的高频转矩脉动问题, 提出了一种基于双高频方波注入法的双绕组永磁同步电机无位置传感器控制策略。建立永磁同步电机高频数学模型, 分析得到转矩脉动与注入信号的解析关系。对于同相位表贴式双绕组永磁同步电机, 当第一套绕组注入高频方波时, 依据2套绕组的位置关系, 推导了第二套绕组应当注入方波信号的形式, 使同一时刻产生的高频转矩脉动代数和为零, 以消除高频转矩脉动。提取2套绕组高频信号中包含的转子位置估计误差, 比较得到同一时刻误差最小值, 并使用龙贝格观测器追踪转子位置角, 提高了位置角估计精度。实验结果表明, 该方法能够完全消除高频转矩脉动, 位置角估计误差减小了60%。
Radiation dose-fractionation in adult Aedes aegypti mosquitoes
Authors: Yamada Hanano , Maïga Hamidou , Kraupa Carina , Somda Nanwintoum Séverin Bimbilé , Mamai Wadaka , Wallner Thomas , Bouyer Jeremy
Published: February 2023

Balancing process efficiency and adult sterile male biological quality is one of the challenges in the success of the sterile insect technique (SIT) against insect pest populations. For the SIT against mosquitoes, many stress factors need to be taken into consideration when producing sterile males that require high biological quality to remain competitive once released in the field. Pressures of mass rearing, sex sorting, irradiation treatments, packing, transport and release including handling procedures for each step, add to the overall stress budget of the sterile male post-release. Optimizing the irradiation step to achieve maximum sterility while keeping off-target somatic damage to a minimum can significantly improve male mating competitiveness. It is therefore worth examining various protocols that have been found to be effective in other insect species, such as dose fractionation. A fully sterilizing dose of 70 Gy was administered to Aedes aegypti males as one acute dose or fractionated into either two equal doses of 35 Gy, or one low dose of 10 Gy followed by a second dose of 60 Gy. The two doses were separated by either 1- or 2-day intervals. Longevity, flight ability, and mating competitiveness tests were performed to identify beneficial effects of the various treatments. Positive effects of fractionating dose were seen in terms of male longevity and mating competitiveness. Although applying split doses generally improved male quality parameters, the benefits may not outweigh the added labor in SIT programmes for the management of mosquito vectors.
Contemporary Management and Clinical Course of Acute Pulmonary Embolism: The COPE Study
Authors: Becattini Cecilia , Agnelli Giancarlo , Maggioni Aldo P. , Dentali Francesco , Fabbri Andrea , Enea Iolanda , Pomero Fulvio , Ruggieri Maria Pia , di Lenarda Andrea , Cimini Ludovica Anna , Pepe Giuseppe , Cozzio Susanna , Lucci Donata , Gulizia Michele M. ,   on behalf of COPE Investigators
Published: February 2023

Background New diagnosis, risk stratification, and treatment strategies became recently available for patients with acute pulmonary embolism (PE) leading to changes in clinical practice and potentially influencing short-term patients' outcomes.

Research question The COntemporary management of PE (COPE) study is aimed at assessing the contemporary clinical management and outcomes in patients with acute symptomatic PE.

Study Design and Methods Prospective, noninterventional, multicenter study. The co-primary study outcomes, in-hospital and 30-day death, were reported overall and by risk categories according to the European Society of Cardiology (ESC) and American Heart Association guidelines.

Results Among 5,213 study patients, PE was confirmed by computed tomography in 96.3%. In-hospital, 289 patients underwent reperfusion (5.5%), 92.1% received parenteral anticoagulants; at discharge, 75.6% received direct oral anticoagulants and 6.7% vitamin K antagonists. In-hospital and 30-day mortalities were 3.4 and 4.8%, respectively. In-hospital death occurred in 20.3% high-risk patients (n = 177), in 4.0% intermediate-risk patients (n = 3,281), and in 0.5% low-risk patients (n = 1,702) according to ESC guidelines. Further stratification in intermediate-high and intermediate-low risk patients did not reach statistical significance, but intermediate-risk patients with sPESI > 0 alone had lower mortality compared to those with one or both among right ventricular dilation at echocardiography or increased troponin. Death or clinical deterioration occurred in 1.5, 5.0, and 9.4% of patients at low, intermediate-low, and intermediate-high risk for death according to ESC guidelines.

Conclusion For the majority of patients with PE, contemporary initial management includes risk stratification and treatment with direct oral anticoagulants. In-hospital mortality remains high in intermediate and high-risk patients calling for and informing research focused on its reduction.

Trial Registration number: NCT03631810.
Noncovalent Interactions in Crowded Benzene Systems: How Much Strain Is Too Much? Attractions Overcome Repulsions!
Authors: Verevkin Sergey P. , Samarov Artemiy A. , Zherikova Kseniya V.
Published: February 2023

In molecular design, large alkyl groups are used to introduce bulk and steric crowding of the catalytic center to improve catalytic efficiency and selectivity. The bulky groups are highly polarizable, increasing their ability to participate in stabilizing noncovalent interactions. The rationalization of noncovalent interaction trends is of both fundamental and practical interest as it provides new design concepts for catalysis and synthesis. Highly congested molecules always present challenges to chemists. Crowded benzene systems are an important class of compounds with well-established thermodynamic properties. The latter were used in this work to develop tools to quantify the degree of stabilization or destabilization in benzene systems crowded with bulky isopropyl and tert-butyl substituents. The basic idea was to quantify the delicate balance between repulsive and attractive interactions inherent in crowded benzene systems. The ensemble of experimental thermodynamic data and DFT-D3 calculations enabled the development of quantitative scales of the dispersion contributions and their understanding at the molecular level.
Self-assembled Patterns Formed in Evaporating Droplets to Analyze Bi-component Homeopathic Preparations in the Low Dilution Range
Authors: Kokornaczyk Maria Olga , Würtenberger Sandra , Baumgartner Stephan
Published: February 2023

Background Homeopathic complex remedies, composed of several homeopathic medicines in the low potency range, are frequently used in the treatment of a number of common disorders. At the same time, they represent an almost unexplored area of research. Are complex remedies just additive mixtures of the components, or are there interactions between the latter leading to new properties of the complex?

Methods In the present study, we analyzed as an example the simple bi-component complex, Luffa 4x – Mercurius bijodatus 9x, by means of patterns from evaporated droplets and tested what influences the complex's single compounds have upon the patterns and if there are any interactions. For this purpose, we compared in a series of five experiments patterns from evaporated droplets of the complex, Luffa 4x – Mercurius bijodatus 9x, and three comparison samples in which one or both of the complex's compounds were replaced by potentized solute. The patterns were photographed and evaluated for their gray-level distribution and texture using the software ImageJ. The experimental set-up's stability was tested by means of systematic control experiments.

Results We found that Mercurius bijodatus 9x significantly influenced the patterns of Luffa 4x, increasing their homogeneity; at the same time, the patterns of Mercurius bijodatus 9x combined with solvent were more heterogeneous than those obtained from a control consisting of two pure solvents.

Conclusion In this phenomenological assay, the complex Luffa 4x – Mercurius bijodatus 9x does not correspond to a simple addition of the components. The exact nature of the underlying interaction needs to be elucidated in further investigations.
Standing Surgical Management of Splint Bone Fractures in 13 Horses: A Comparison to Management Under General Anaesthesia
Authors: Auffret Vincent , Bonilla Alvaro G.
Published: February 2023

Objective The aim of this article was to describe the technique and outcomes of standing surgical management of splint bone fractures and to compare outcome variables and hospitalization cost to a group with similar fractures treated under general anaesthesia.

Study Design It is a single-institution retrospective study. Surgical technique, surgical time, hospitalization cost and complications were retrieved from the medical records of horses treated surgically for splint bone fractures (2008–2020). Owner telephone follow-up provided data about athletic outcome, client satisfaction and cosmetic appearance.

Results Forty-nine horses (13 standing, 36 under general anaesthesia) with 57 fractures (18 contaminated and 39 non-contaminated) were included. Seven fractures were in the proximal third (4 standing, 3 under general anaesthesia), 18 in the middle third (5 standing, 13 under general anaesthesia) and 30 were distal (4 standing, 26 under general anaesthesia). No significant difference between groups in surgical time was found (p= 0.8). Average total cost was 522 CAN$ lower for the standing group for non-contaminated fractures (p= 0.02). Three horses of the general anaesthesia group demonstrated postoperative colic signs and one case of the standing group was re-operated due to sequestration. Based on follow-up information (range: 3.8-151.2 months), no significant differences in cosmetic and athletic outcomes were found between groups.

Conclusion Surgical management of splint bone fractures in the standing horse is a valuable alternative for horses selected based on behaviour. When compared to general anaesthesia, standing management of splint bone fractures did not alter the surgical time or outcome variables and avoided general anaesthesia-associated risks.
Social trust, social capital, and subjective well-being of rural residents: micro-empirical evidence based on the Chinese General Social Survey (CGSS)
Authors: Xu Haiping , Zhang Chuqiao , Huang Yawen
Published: February 2023

Despite a recent line of research highlighting trust as an important determinant of residents’ happiness in Western countries, empirical evidence regarding the strength of these linkages in the developing world needs to be more comprehensive and conclusive. This paper contributes to this literature by performing a deeper examination into the trust-based explanation of happiness and, particularly, exploring the mediating role of social capital in rural China, where rapid economic growth coexists with gradual and fundamental social changes. Using data from the nationally representative cross-sectional Chinese General Social Survey (CGSS) in 2012, 2013, and 2015, we indicate that trust positively affects the happiness of rural residents and social capital. Our findings support the role of social capital in mediating happiness prediction. Furthermore, additional tests suggest heterogeneous social capital for different ages and degrees of regional market competition. Specifically, the mediating effect of social capital on rural residents over 30 years old (inclusive) and living in high-market competition areas is significant. These findings provide a valuable direction for the government that producing an environment that enhances social networks and facilitates the exchange of social support holds promise for improving the life satisfaction of the rural Chinese population. Trust can significantly improve rural residents’ happiness through increasing social capital. The government should effectively manage the rural social trust crisis and help rural residents build social capital in multiple ways, improving the life satisfaction of rural residents.
Doped titanium disulfide demonstrates increased adsorption, diffusion
Authors: Liebendorfer Adam
Published: February 2023

Density Functional Theory models point to potential for new anode material in next-generation batteries.
Realization of an advanced super-mirror solid-state neutron polarizer for the instrument PF1B at the Institut Laue–Langevin
Authors: Petoukhov A. K. , Nesvizhevsky V. V. , Bigault T. , Courtois P. , Devishvili A. , Jullien D. , Soldner T.
Published: February 2023

In this last of a series of three papers on the development of an advanced solid-state neutron polarizer, we present the final construction of the polarizer and the results of its commissioning. The polarizer uses spin-selective reflection of neutrons by interfaces coated with polarizing super-mirrors. The polarizer is built entirely in-house for the PF1B cold neutron beam facility at the Institut Max von Laue–Paul Langevin (ILL). It has been installed in the PF1B casemate and tested under real conditions. The average transmission for the “good” spin component is measured to be >30%. The polarization averaged over the capture spectrum reaches a record value of Pn ≈ 0.997 for the full angular divergence in the neutron beam, delivered by the H113 neutron guide, and the full wavelength band λ of 0.3–2.0 nm. This unprecedented performance is due to a series of innovations in the design and fabrication in the following domains: choice of the substrate material, super-mirror and anti-reflecting multilayer coatings, magnetizing field, and assembling process. The polarizer is used for user experiments at PF1B since the last reactor cycle in 2020.
Electron pulse-dilation diagnostic instruments
Authors: Trosseille C. , Nagel S. R. , Hilsabeck T. J.
Published: February 2023

During the past decade, a number of diagnostic instruments have been developed that utilize electron pulse-dilation to achieve temporal resolution in the 5–30 ps range. These development efforts were motivated by the need for advanced diagnostics for high-energy density physics experiments around the world. The new instruments include single- and multi-frame gated imagers and non-imaging detectors that record continuous data streams. Electron pulse-dilation provides high-speed detection capability by converting incoming signals into a free electron cloud and manipulating the electron signal with electric and magnetic fields. Here, we discuss design details and applications of these instruments along with issues and challenges associated with employing the electron pulse-dilation technique. Additionally, methods to characterize instrument performance and improve tolerance to gamma and neutron background radiation are discussed.
Linear analytical model for magneto-Rayleigh–Taylor and sausage instabilities in a cylindrical liner
Authors: Dai J. L. , Sun Y. B. , Wang C. , Zeng R. H. , Zou L. Y.
Published: February 2023

Recent experimental and numerical results demonstrates that the interfacial motion of a liner Z-pinch during the early stage of implosion may be controlled by the coupled effects of magneto-Rayleigh–Taylor (MRT), sausage, and kink instabilities. However, previous treatments of sausage instability have not considered the mechanical properties of the liner material. In this paper, we present an analytical model that allows us to study the effects of liner viscosity and elasticity on the coupling effects of MRT and sausage instabilities, and we further assume that the wavelengths are much smaller than the liner thickness by neglecting the feedthrough effect. The dispersion relations are analyzed. It is found that viscosity suppresses short-wavelength perturbations, and longer wavelengths are needed to achieve the fastest growing mode as the viscosity grows. Elasticity also strongly suppresses short-wavelength perturbations and eventually leads to the appearance of a cutoff wavenumber beyond which the interface always remains stable. In particular, the present approach provides the basis for the development of a more general theory that would also include magnetohydrodynamic instabilities and would allow a more accurate description of liner motion.
Dopant-enhanced sodium and potassium-ion adsorption and diffusion in two-dimensional titanium disulfide
Authors: Nair A. K. , Da Silva C. M. , Amon C. H.
Published: February 2023

Two-dimensional (2D) titanium disulfide (TiS2) is the lightest transition-metal dichalcogenide (TMD). It exhibits relatively better adsorption and diffusion of sodium (Na) and potassium (K) ions than other TMDs, such as MoS2 (molybdenum disulfide) and ReS2 (rhenium disulfide), making it a promising anode material for alkali-ion batteries. Previous studies have found that doping significantly enhances the adsorption and diffusion capabilities of 2D TMDs. For the first time, this work reports the adsorption of Na and K ions on doped TiS2 monolayers using first-principles calculations, where the Ti atom is substituted by 3d-transition metals, including iron (Fe), cobalt (Co), nickel (Ni), and copper (Cu). Metal-atom doping induces remarkably stronger binding of alkali ions on the surface of TiS2, with adsorption energies ranging from −2.07 to −2.48 eV for Na and −2.59 to −3.00 eV for K. The diffusion barrier energies for alkali ions decrease in the proximity of the doping site and increase as the ions travel away from the doping site for Fe-, Co-, and Ni-doped TiS2. The average open circuit voltage increases dramatically when Na ions are adsorbed on Fe-doped TiS2 (by 62%) and Co-doped TiS2 (by 61%), while K ions result in a moderate improvement of 9% and 8%, respectively. These findings suggest that metal-atom doping considerably improves the electrochemical properties of 2D TiS2, potentially enabling its use as anode materials in Na- and K-ion batteries.
Integrating test device and method for creep failure and ultrasonic response of methane hydrate-bearing sediments
Authors: Hu Qiaobo , Li Yanlong , Sun Xiaofeng , Chen Mingtao , Bu Qingtao , Gong Bin
Published: February 2023

Clarifying the creep behaviors of hydrate-bearing sediment (HBS) under long-term loading is crucial for evaluating reservoir stability during hydrate exploitation. Figuring out a way of characterizing deformation behaviors and their geophysical responses to HBS is the basis for modeling creep behaviors. In this study, we propose a novel device to test time-dependent deformation and the ultrasonic response of HBS under high-pressure and low-temperature. The experimental device consists of a high-pressure chamber, an axial-load control system, a confining pressure system, a pore pressure system, a back-pressure system, and a data collection system. This testing assembly allows temperature regulation and independent control of four pressures, e.g., confining pressure, pore pressure, back pressure, and axial loading. Columned artificial HBS samples, with a diameter of 39 mm and a height of 120 mm, can be synthesized in this device. Afterward, in situ creep experiments can be achieved by applying stable confining pressure and axial load, together with geophysical signals acquisition. During loading, the stress–strain relationships and ultrasonic data can be obtained simultaneously. Through analyzing the stress–strain relationship and ultrasonic data, the macroscopical failure and microcosmical creep deformation law of the samples can be figured out. Preliminary experiments verified the applicability of the device. The method provides some significance for field observation of reservoir failure via geophysical techniques during hydrate exploitation.
Modification of micro-crystalline graphite and carbon black by acetone, toluene, and phenol
Authors: Milenov Teodor I. , Dimov Dimitar A. , Avramova Ivalina A. , Kolev Stefan K. , Trifonov Dimitar V. , Avdeev Georgi V. , Karashanova Daniela B. , Georgieva Biliana C. , Ivanov Kamen V. , Valcheva Evgenia P.
Published: February 2023

The chemical interactions of two types of graphite and two types of carbon black (CB) with acetone, toluene, and phenol were studied in order to evaluate the influence of chemical treatment on the structure and morphology of the carbon phases. The experimental treatment of carbon phases was carried out at room temperature for 1 hour. The chemical and phase composition were studied by x-ray photoelectron (XP) and Raman spectroscopies, while the morphology and structure were determined by powder x-ray diffraction, as well as transmission electron microscopy techniques. To shed light on the most probable explanation of the observed results, we performed simulations and calculations of the binding energies of acetone, toluene, and phenol with model carbon phases: a perfect graphene sheet and a defective graphene sheet containing various structural defects (vacancies as well as zigzag and armchair edges). Simulations show that all non-covalent and most covalent coupling reactions are exothermic, with acetone coupling having the higher calorimetric effect. Based on the results of the simulations and the XP spectroscopy measurements, the probable reactions taking place during the respective treatments are outlined. The conducted studies (both theoretical and experimental) show that the treatment of graphite powders and CB with acetone, toluene, or phenol can be used as a preliminary stage of their modification and/or functionalization, including their conversion into graphene-like (defective graphene, reduced graphene oxide, and/or graphene oxide) phases. For example, the treatment of SPHERON 5000 with acetone significantly facilitates their subsequent modification with laser radiation to graphene-like phases.
Layer-by-layer assembly of metal-organic framework thin films: Fabrication and advanced applications
Authors: Chen Dong-Hui , Gliemann Hartmut , Wöll Christof
Published: February 2023

Metal-organic frameworks (MOFs) are a class of crystalline porous coordination materials, which are assembled from inorganic nodes and organic linkers. Numerous applications, such as gas storage, molecule separation, catalysis, optical sensing, and charge transport, benefit from the outstanding properties of MOF materials. More advanced applications, e.g., in the electronics and optoelectronics area, demand homogeneous and monolithic MOF thin films. Recent studies demonstrated that surface-mounted MOFs (SURMOFs) are well suited to fulfill the requirements for the integration of MOFs into devices. As a crystalline thin-film material with tunable thickness, SURMOFs have been widely used in the optimization of chromophore stacking, electrical transport, stimuli-response, etc. The fabrication of SURMOFs is carried out employing a layer-by-layer (LbL) assembly technique, and it can yield MOF thin films with a well-defined orientation, tunable thickness, and editable crystalline heterostructure. We summarize the LbL assembly methods for SURMOF fabrication and the realization of advanced SURMOF architectures, including optical and electronic applications as well as the integration of photoactive SURMOFs and SURMOF-derived materials in technical devices. We conclude with a discussion of the challenges and prediction of the future of SURMOF materials.
Dynamic behavior of compound droplets with millimeter-sized particles impacting substrates with different wettabilities
Authors: Xing Lei , Li Jinyu , Jiang Minghu , Zhao Lixin
Published: February 2023

The dynamic behavior of compound droplets, which are made up of a millimeter-sized particle and distilled water, impacting substrates of different wettabilities is investigated via high-speed photography. The effects of the size of the particle within the compound droplet, substrate contact angle, and impact height on the deformation of the droplets and the characteristics of the impact are analyzed. It is found that the collisions of compound droplets with substrates can be classified into four categories based on the observed experimental phenomena that occur during the impact. These categories are referred to as adhesion collision, rebound collision, daughter-droplet collision (or partial rebound collision), and breakup collision. We consider both the impact of water droplets and compound droplets (with one of two different-sized particles) on substrates of different wettabilities. The effects of inertia, surface tension, and adhesion between the substrate and the liquid droplet, and adhesion between the particle and the liquid droplet are considered to explain the different collision phenomena of compound droplets and reveal the evolution mechanism of the droplet morphologies in the experiments. Furthermore, the effects of the height from which the droplet is released and the contact angle of the substrate (i.e., its wettability) on the maximum spreading diameter and maximum jet height of the droplet are presented quantitatively. The effect of the size of the particle within the compound droplet and the substrate contact angle on the dynamic behavior of the compound droplet subject to impact with the substrate is also described.
Fast calibration of magnetic field coils in miniaturized NMRGs from Rabi oscillation of nuclear spins
Authors: Peng Jinpeng , Liu Zhanchao , Wang Tengyue , Mao Yunkai , Zhou Binquan
Published: February 2023

We propose a fast and accurate method for the in situ calibration of the transverse coils in miniaturized nuclear magnetic resonance gyroscopes based on the Rabi oscillation of hyperpolarized gaseous 129Xe nuclear spins. In contrast to the conventional method based on the free induction decay initial amplitude of different pulse durations, this method circumvents the error introduced by the frequency detuning of the transverse driving field. We experimentally confirm that the accuracy of the calibration is influenced by the longitudinal relaxation time T1, the transverse relaxation time T2, and the magnitude of the transverse driving field B1. Through the numerical simulation of Bloch equations, we show that the behavior of My′ and Mz can be completely specified by two dimensionless quantities a and b, and we provide a ready-to-use selection criterion of b ≥ 24 for choosing the proper B1. By switching the embedded magnetometer into the longitudinal mode, we demonstrate the effectiveness and efficiency of our new calibration method. Finally, we examine the effectiveness of the selection criterion with our new calibration method. This method is expected to improve the authenticity of coil calibration and relaxation measurement in a more efficient way.
Shear-induced phase transition in the aqueous solution of an imidazolium-based ionic liquid
Authors: Sharma Gunjan , Mitra Saheli , Kamil Syed Mohammad , Ghosh Sajal Kumar
Published: February 2023

An ionic liquid (IL) is a salt in the liquid state that consists of a cation and an anion, one of which possesses an organic component. Because of their non-volatile property, these solvents have a high recovery rate, and, hence, they are considered as environment-friendly green solvents. It is necessary to study the detailed physicochemical properties of these liquids for designing and processing techniques and find suitable operating conditions for IL-based systems. In the present work, the flow behavior of aqueous solutions of an imidazolium-based IL, 1-methyl-3-octylimidazolium chloride, is investigated, where the dynamic viscosity measurements indicate non-Newtonian shear thickening behavior in the solutions. Polarizing optical microscopy shows that the pristine samples are isotropic and transform into anisotropic after shear. These shear thickened liquid crystalline samples change into an isotropic phase upon heating, which is quantified by the differential scanning calorimetry. The small angle x-ray scattering study revealed that the pristine isotropic cubic phase of spherical micelles distort into non-spherical micelles. This has provided the detailed structural evolution of mesoscopic aggregates of the IL in an aqueous solution and the corresponding viscoelastic property of the solution.
“Absolute zero” temperature in a vertically vibrated granular system
Authors: Cai Hui , Sun Changcheng , Qin Shengsheng , Miao Guoqing
Published: February 2023

In thermodynamics, absolute zero is the coldest temperature and will never be reached because the thermal motion of microscopic particles never ceases. However, this situation could be changed for a collection of macroscopic particles. In the present paper, an experimental study was performed to explore the possible lowest temperature in a vertically vibrated granular system. It was found that the granular “absolute zero” temperature appears when the vibrating intensity is adjusted to about 4.6 times the gravitational acceleration. At this temperature, the macroscopic particles are arranged closely and behave like a rigid body without relative motions during the vibration. Near the absolute zero, inelastic collisions and energy transfer are responsible for the variation of granular temperature with time and vibrating parameters. Interestingly, the temperature variation reveals that the vibrated macroscopic particles are neither a crystal nor an amorphous system. This study introduces the granular entropy, including entropy generation and entropy flow, to describe the order of the vibrated particles. The entropy change could be illustrated by the temperature profiles of the granular system and its outside. It was also found that, unlike microscopic particles, which could maintain their entropy at a constant temperature, a granular system necessarily behaves completely disordered unless the system achieves the absolute zero granular temperature.
Decomposition of the skin-friction coefficient of compressible boundary layers
Authors: Xu Dongdong , Ricco Pierre , Duan Lian
Published: February 2023

We derive an integral formula for the skin-friction coefficient of compressible boundary layers by extending the formula of Elnahhas and Johnson [“On the enhancement of boundary layer skin friction by turbulence: An angular momentum approach,” J. Fluid Mech. 940, A36 (2022)] for incompressible boundary layers. The skin-friction coefficient is decomposed into the sum of the contributions of the laminar coefficient, the change of the dynamic viscosity with the temperature, the Favre–Reynolds stresses, and the mean flow. This decomposition is applied to numerical data for laminar and turbulent boundary layers, and the role of each term on the wall-shear stress is quantified. We also show that the threefold integration identity of Gomez et al. [“Contribution of Reynolds stress distribution to the skin friction in compressible turbulent channel flows,” Phys. Rev. E 79(3), 035301 (2009)] and the twofold integration identities of Wenzel et al. [“About the influences of compressibility, heat transfer and pressure gradients in compressible turbulent boundary layers,” J. Fluid Mech. 930, A1 (2022)] and Xu et al. [“Skin-friction and heat-transfer decompositions in hypersonic transitional and turbulent boundary layers,” J. Fluid Mech. 941, A4 (2022)] for turbulent boundary layers all simplify to the compressible von Kármán momentum integral equation when the upper limit of integration is asymptotically large. The dependence of these identities on the upper integration bound is studied. By using asymptotic methods, we prove that the multiple-integration identity of Wenzel et al. [“About the influences of compressibility, heat transfer and pressure gradients in compressible turbulent boundary layers,” J. Fluid Mech. 930, A1 (2022)] degenerates to the definition of the skin-friction coefficient when the number of integrations is asymptotically large.
Neural parameter calibration for large-scale multiagent models
Authors: Gaskin Thomas , Pavliotis Grigorios A. , Girolami Mark
Published: February 2023

Computational models have become a powerful tool in the quantitative sciences to understand the behavior of complex systems that evolve in time. However, they often contain a potentially large number of free parameters whose values cannot be obtained from theory but need to be inferred from data. This is especially the case for models in the social sciences, economics, or computational epidemiology. Yet, many current parameter estimation methods are mathematically involved and computationally slow to run. In this paper, we present a computationally simple and fast method to retrieve accurate probability densities for model parameters using neural differential equations. We present a pipeline comprising multiagent models acting as forward solvers for systems of ordinary or stochastic differential equations and a neural network to then extract parameters from the data generated by the model. The two combined create a powerful tool that can quickly estimate densities on model parameters, even for very large systems. We demonstrate the method on synthetic time series data of the SIR model of the spread of infection and perform an in-depth analysis of the Harris–Wilson model of economic activity on a network, representing a nonconvex problem. For the latter, we apply our method both to synthetic data and to data of economic activity across Greater London. We find that our method calibrates the model orders of magnitude more accurately than a previous study of the same dataset using classical techniques, while running between 195 and 390 times faster.
Swearing as a Leadership Tool
Authors: Wilson Nick , Wedlock Joshua
Published: February 2023

Although swearing is often perceived as intrinsically offensive language, it is how swearing use is indexed
against a person’s understanding of local social norms that constructs swearing as offensive. This paper presents an analysis of
swearing within a social context where high frequency swearing is a norm: a male rugby team in New Zealand. Drawing upon a dataset
collected from ethnographically collected authentic interactions, an analysis of the frequency of swear words and a comparison
with other English corpora is presented, followed by an interactional sociolinguistic analysis of how swearing is used in
interactions. The aim of the paper is to demonstrate not only how swearing can be used to engender solidarity, but that a range of
socio-pragmatic functions of swearing such as intensifying and indexing a vernacular identity, can be used in performing
leadership.
A ferroelectric memristor with a capacitor-like structure for neuromorphic computing
Authors: Xie Donggang , Sun Qinchao , Geng Qianyi , Su Jie , Li Qiang , Ni Hao
Published: February 2023

This paper presents a ferroelectric memristor-based synaptic device with a capacitor-like structure and nonvolatile multilevel conductance. Conductance modulation can be achieved by manipulating the barrier height through polarization inversion and the mimicking of the important synaptic functions, such as long-term plasticity and spike-timing-dependent plasticity, have been implemented. By extracting device parameters, a simulated artificial neural network is constructed for image recognition, and it can achieve 91.2% recognition accuracy for Modified National Institute of Standards and Technology images. These results show the potential of this device in building brain-like computing systems and further enrich the research of ferroelectric materials in realizing artificial synapses.
Concept of the generalized reduced-order particle-in-cell scheme and verification in an axial-azimuthal Hall thruster configuration
Authors: Reza Maryam , Faraji Farbod , Knoll Aaron
Published: February 2023

The reduced-order particle-in-cell (PIC) scheme is a novel modeling approach that enables computationally efficient electrostatic kinetic simulations of plasma. In our previous publications, we demonstrated that a proof-of-concept implementation of this novel PIC scheme resolves the multi-dimensional plasma processes and their interactions in a Hall thruster in a manner close to traditional electrostatic PIC codes. In this work, we extend our efforts on this topic and present a mathematically mature formulation for the dimensionality reduction of Poisson’s equation in the Vlasov–Poisson system, which enables the generalized reduced-order ‘quasi-multi-dimensional’ PIC scheme. The applicability of the dimensionality-reduction approach to solve general 2D Poisson problems is numerically verified. Next, we present several reduced-order quasi-2D (Q2D) simulations of a well-defined axial-azimuthal simulation case from the literature using approximation orders of the 2D problem whose computational costs are 2%–15% of a full-2D simulation. It is shown that these reduced-order simulations allow us to recover the same characteristics, behaviors and effects reported in the literature regarding the azimuthal instabilities in Hall thrusters. Moreover, in terms of the time-averaged plasma properties, it was found that, when increasing the approximation order, the error associated with the Q2D simulations’ predictions decreases from 15% to 4% for the electric field and from 20% to 2% for the ion number density. We have additionally discussed a series of sensitivity analysis results, including the influence of the initial number of macroparticles per cell on the predictions of the Q2D simulations. According to the detailed results and analyses presented, we conclude that the generalized reduced-order PIC scheme serves as a rigorous foundation for eventual cost-effective and comprehensive three-dimensional kinetic studies of the physics in Hall thrusters and similar electrostatic plasma technologies.
Photoinduced spin-polarized transport and controllable valley-triplet pairing states in a silicene-superconductor junction
Authors: Huang Chuan-Shuai
Published: February 2023

We theoretically investigate the spin-polarized subgap transport and valley-triplet pairing states in a silicene-superconductor junction. By using the nonequilibrium Green’s function, it is found that the subgap conductance is strongly affected by the spin polarization induced by an off-resonant circularly polarized light. More importantly, the presence of valley-mixing scattering at the interface could result in a valley-triplet Andreev reflection (AR) process, where the incident electrons and reflected holes come from the same valley. We also find that the amplitude of the valley-triplet AR is controllable by tuning the intensity of the light, the position of the Fermi level, and even the interface coupling strength. Particularly, the fully valley-polarized conductance spectrum shows distinctive behaviors, which is beneficial for us to verify and detect the possible valley-triplet pairing states as well as the spin/valley polarizations in silicene. Our results may pave the way for the applications of silicene in spin-valleytronics.