bluuebunny/crossref_metadata_2025 huggingface dataset:
The success of optical variability in uncovering active galactic nuclei in low stellar mass galaxies
Authors: Bernal S. , Sánchez-Sáez P. , Arévalo P. , Bauer F. E. , Lira P. , Sotomayor B.
Published: January 2025

Context. The origins of supermassive black holes (SMBHs) at the centers of massive galaxies are a topic of intense investigation. One way to address this subject is to identify the seeds of SMBHs as intermediate-mass black holes (IMBHs; 100 M⊙ < MBH < 106 M⊙). IMBHs are expected to be found at the centers of low stellar mass galaxies (LSMGs).

Aims. Our goal is to complete the census of SMBHs in LSMGs. In this work our aim is to establish the purity of active galactic nucleus (AGN) selection by algorithms based on optical variability and to characterize the black hole population found through this method.

Methods. We used random forest algorithms to classify all objects in a large portion of the sky, using optical light curves obtained from, or built from images provided by, the Zwicky Transient Facility (ZTF). We compared different selection sets based on alerts (flux changes with at least 5σ significance) or complete light curves derived from different photometric selection algorithms. The AGN candidates thus selected were cross-matched with objects in the NASA-Sloan Atlas (NSA) of local galaxies, with M* < 2 × 1010 M⊙. The AGN nature of these candidates was verified and characterized using archival optical spectra from SDSS. We further established the fraction of candidates with counterparts in the eROSITA Data Release 1 catalog of X-ray sources.

Results. From an initial sample of 506 candidates, 415 have good-quality spectra. Among these 415 objects we found significant broad Balmer lines in the spectra for 86% (357) of the candidates. When considering BPT classifications, five additional candidates were confirmed, resulting in 87% (362) confirmed candidates. Specifically, broad Balmer lines were detected in 94%–98% of the AGN candidates selected from complete light curves and in 80% of those selected from the less frequent ZTF alerts. The black hole masses estimated from the spectra range from 2.2 × 106 M⊙ to 4.2 × 107 M⊙, reaching lower values for the candidates selected using the more sensitive light curves. The black hole masses obtained cluster around 0.1% of the stellar mass of the host from the NSA catalog. Two-thirds of the AGN candidates are classified as Seyfert or composite by their narrow emission line ratios (BPT diagnostics), while the rest are star-forming. Almost all the candidates classified as Seyfert and over 50% of those classified as star-forming have significant broad emission lines (BELs). We found X-ray counterparts for 67% of the candidates that fall in the footprint of the eROSITA-DE DR1. Considering only the candidates with significant BELs, the matches increase to 75%, regardless of where they appear in the BPT diagnostics diagrams.
Spectral and photometric characterization of (98943) Torifune in preparation for the Hayabusa2# spacecraft flyby
Authors: Bourdelle de Micas J. , Perna D. , Fornasier S. , Dotto E. , Ieva S. , Barucci M. A. , Geem J. , Hasegawa S. , Ishiguro M. , Kitazato K. , Kuroda D. , Mazzotta Epifani E. , Palomba E. , Yoshikawa M. , Hirabayashi M.
Published: January 2025

Context. After a successful sample-return mission to the asteroid (162173) Ryugu, the Hayabusa2 spacecraft is currently on its way to encounter two near-Earth asteroids: (98943) Torifune (formerly known as 2001 CC21) and 1998 KY26.

Aims. In this article, we study the asteroid (98943) Torifune, the first object that is to be visited by the spacecraft during its extended mission. To prepare for its encounter with the spacecraft, it is crucial to study this object from Earth. We conducted several ground-based observations to characterize this asteroid and understand its mineralogy.

Methods. In January and February 2023, we carried out spectroscopic and photometric observations at the 2.56 m Nordic Optical Telescope, in the visible and near-infrared ranges, covering different rotational phases of the asteroid.

Results. Based on spectra analysis in the visible and near-infrared ranges, confirmed by the color studies, we determined that Torifune belongs to the Sq-type, according the Bus-DeMeo taxonomy. Assuming this taxonomy and its equivalent diameter (D ∼ 465 ± 15 m), we estimated the mass of this asteroid to be 1.81 ± 0.11  ×  1011 kg. In term of mineralogy, we found a close match with ordinary L chondrites.

Conclusions. As our observations covered almost a complete rotation phase, we did not find any spectral variation at different rotational phases, meaning that there is no substantial heterogeneities on Torifune’s surface. We compared the spectral slope of (98943) Torifune with that of the S-complex members of the Lucienne family. However, further studies, especially dynamical ones, are needed to confirm whether this object originates from the Lucienne family.
Spectroscopic confirmation of a dust-obscured, possibly metal-rich dwarf galaxy at z ∼ 5
Authors: Bisigello L. , Gandolfi G. , Feltre A. , Arrabal Haro P. , Calabrò A. , Cleri N. J. , Costantin L. , Girardi G. , Giulietti M. , Grazian A. , Gruppioni C. , Hathi N. P. , Holwerda B. W. , Llerena M. , Lucas R. A. , Pacucci F. , Prandoni I. , Rodighiero G. , Seillé L.-M. , Wilkins S. M. , Bagley M. , Dickinson M. , Finkelstein S. L. , Kartaltepe J. , Koekemoer A. M. , Papovich C. , Pirzkal N.
Published: January 2025

We present the first spectroscopic confirmation of a dust-obscured dwarf galaxy, CEERS-14821. The analysis was performed by combining JWST NIRCam broadband photometry and NIRSpec/PRISM spectroscopic data. From the detection of multiple rest-frame optical lines, we derive that CEERS-14821 is located at z = 4.883 ± 0.003. Moreover, from a secure detection of the Hα and Hβ, we derive that the galaxy has a dust extinction ranging from AV = 2.2−0.6+0.5 to AV = 3.4−0.9+0.7, depending on the assumed reddening law. This value is extremely large given that we estimated a low stellar mass, that is, log10(M/M⊙) = 8.17−0.04+0.05 or log10(M/M⊙) = 8.65−0.05+0.06, based on two different dust extinction laws. Moreover, the combination of different metallicity tracers and the spectro-photometric fit suggests that the galaxy may also be metal-rich, with 12 + log10(O/H)> 8.3, but a low metallicity value cannot be totally ruled out. The high metallicity value would be above the expectation based on the mass-metallicity relation. Both metallicity estimations are above the expectations based on the fundamental mass-metallicity relation since CEERS-14821 is going through a burst of star formation. The constraints on a possible active galactic nucleus presence are limited and loose, but they point towards a possible non-dominant contribution (fAGN <  0.5 with respect to the total dust luminosity). Based on the rest-frame optical images, this source has a size compatible with galaxies of similar stellar masses and at similar redshifts. Finally, CEERS-14821 may be part of a larger galaxy overdensity, but there are no other galaxies closely interacting with it (within 30 Mpc).
Anisotropic tidal dissipation in misaligned planetary systems
Authors: Auclair-Desrotour Pierre , Boué Gwenaël , Loire Baptiste
Published: January 2025

Context. Tides are the main driving force behind the long-term evolution of planetary systems. The associated energy dissipation and momentum exchanges are commonly described by Love numbers, which relate the exciting potential to the tidally perturbed potential. These transfer functions are generally assumed to depend solely on tidal frequency and body rheology, following the isotropic assumption, which presumes invariance of properties by rotation about the centre of mass.

Aims. We examine the limitations of the isotropic assumption for fluid bodies, in which Coriolis acceleration breaks spherical symmetry, resulting in rotational scattering and complex tidal responses.

Methods. Using angular momentum theory, we derived a new formalism to calculate the tidal rates of energy and momentum transfers in non-isotropic cases. We applied this formalism to the Earth-Moon system to assess the effects of anisotropy in planet-satellite systems with misaligned spin and orbital angular momenta.

Results. Our findings indicate that the isotropic assumption can introduce significant errors in planetary evolution models, particularly in the dynamical tide regime. These errors stem from forced wave resonances, with inaccuracies in energy dissipation scaling in proportion to resonance amplification factors.
Impact of artificial rice from Gracilaria sp. seaweed on Superoxide Dismutase (SOD) levels in prediabetic and diabetic patients
Authors: Purwaningsih Sri , Wahyu Ramadhan
Published: January 2025

Analog rice made from local flour and seaweed flour underwent proximate and fiber content tests, followed by clinical trials involving prediabetic and diabetic sufferers over 42 days. The aim of this study was to determine the effect of consuming seaweed-based rice analogues on Superoxide Dismutase (SOD) levels in prediabetic and diabetic sufferers. Initial assessments were conducted on days 21 and 42 as the final evaluation. The study involved 40 respondents (both prediabetic and diabetic patients), with 20 consuming regular rice and 20 consuming analog rice. Both groups had the same vegetables and side dishes. Additionally, the chemical content of the product was tested. The SOD activity in this study was measured using a colorimetric assay method. The results showed that consumption of analog rice significantly reduced blood SOD levels in prediabetic and diabetic sufferers (initial value 0.59 ± 0.12 and final value 0.41 ± 0.16), whereas regular rice consumption significantly increased blood SOD levels (initial value 0.71 ± 0.20 and final value 0.87 ± 0.32). The chemical composition of the seaweed-based rice analog included 61.57 ± 0.49% water, 13.22 ± 0.04% protein, 0.11 ± 0.01% ash, 0.74 ± 0.01% fat, 34.38 ± 0.40% carbohydrates, and 10.17 ± 0.15% fiber. Ultimately, this research opens a new avenue, suggesting that artificial rice can serve not only as a primary energy source but also as a functional food with potential antidiabetic properties
The Development of Hybrid Food as Meat Analog Strips Based on Seaweed Ulva ohnoi and Surimi
Authors: Maulida Arlin , Ramadhan Wahyu , Santoso Joko
Published: January 2025

Meat analogues have been gaining popularity as a sustainable and health-conscious alternative to traditional meat products, driven by increasing consumer awareness of environmental benefits. However, there remains a gap in the market for meat analogues that not only mimic meat texture but also offer enhanced nutritional benefits, particularly in terms of fiber content. Meat analogue strips from Ulva ohnoi and surimi underwent proximate, fiber, and texture profile analysis. The aim of the study was to determine the best formula between the ratio of Ulva ohnoi and surimi inclusion in meat analogue strips along with evaluating the physicochemical characteristics of the resulting product. This study also involved panelists to assess the hedonic level of consumer acceptance of the produced products. The results showed that F5, with 5% Ulva ohnoi and 20% surimi, was the best formula with a sensory value of color 7.21 and texture 6.08. The chemical composition of meat analogue strip F5 includes 2.63 ± 0.54% moisture content, 10.12 ± 2.28% ash content, 3.89 ± 0.87% fat, 13.86 ± 0.31% protein, 59.26 ± 1.93% carbohydrate, and 10.23 ± 0.00% fiber. Eventually, this study opens up new alternatives, showing that meat analogue strips not only serve as an energy source but also as a potential high-fiber healthy snack.
Monitoring Surface Deformation Before the M7.0 Kumamoto and M6.6 Chitose Earthquakes for Precursor
Authors: Zulhamidi Nur Fatin Irdina , Abdullah Mardina , Nurul Shazana Abdul Hamid , Yusof Khairul Adib
Published: January 2025

Earthquakes have resulted in significant damage; however, the extent of the ground observation coverage remains limited. Thus, a deeper understanding of seismic activity and its precursors holds promise in mitigating earthquake hazards. This study aims to monitor the surface deformation for earthquake precursor identification. Interferometric Synthetic Aperture Radar (InSAR) observations were used to identify surface deformation before and after seismic events. The analysis of Sentinel-1 images provided a time series of land subsidence and deformation, allowing for the analysis of deformation evolution. A significant phase difference was observed between the preand post-event interferograms for both the Kumamoto and Chitose earthquakes. The phase map shows the phase difference caused by the energy released prior to the earthquake; hence, it could be a possible precursor for earthquakes. Developing strategies and implementing early warning systems could be effective in reducing the impact of earthquakes and protecting vulnerable regions from their severe consequences.
Impact of Community-based Adaptation Methods in Creating Resilient Communities in Indonesia and Philippines
Authors: Tota Wayne , Abdul Maulud Khairul Nizam , Md Noor Noorashikin
Published: January 2025

Asian coastal communities have adopted community-based-adaptation (CBA) methods to foster resilience on climate change impacts. In Indonesia, implementation of CBA in communities had a positive resilience score of 35%. Robustness of infrastructure and cohesion in community disaster-preparedness was measured using the standardised resilience index. In a 5 year period, economic-climatic related losses had a 40% decrease. Improvements were observed in disaster management, aquaculture, food, and water-security resilience, thus, 25% water management practices, also including irrigation systems and flood control measures. Effective CBA were exemplified by Climate-Village (Kampung-Iklim) Indonesia where collaborative-governance, public-awareness, and sustainable-practices, increased community participation and improved local environmental conditions. Furthermore, riverbank projects in Philippines included modern techniques integrated with indigenous-knowledge enhanced community-resilience in fisheries and aquaculture, food security and sustainable water management. Community engagement was crucial for successful adaptation, and this led to responsibility and ownership among community members. These adaptation projects improved livelihoods through sustainable agricultural practices and income-generation through diversification. Communities showed sustained resilience due to increased and positive ecological footprint. Flood control structures were observed to increase risk of maladaptation by downstream flooding. This paper focuses on assessing impact of community-based adaptation methods in creating resilient communities in Asia.
40-jähriger Patient mit perianalen Schmerzen, Infektzeichen und Stuhlverhalt
Authors: Killermann Martin , Weigert Edith , Dauer Marc
Published: January 2025

Wir präsentieren einen Fall mit etwas ungewöhnlicher Ursache für perianale Schmerzen und Stuhlverhalt.
Recent Advances in Deoxygenative Thioether Synthesis Using Oxygenated Sulfur Surrogates
Authors: Lam Long Yin , Ma Cong
Published: January 2025

Thioethers play a crucial role in therapeutics, diagnostics, and functional materials. Traditionally, their synthesis involved the use of thiols or their derivatives, which are associated with unpleasant odors and potential health risks. Recently, significant research has focused on employing oxygenated sulfur compounds, such as sulfonyl derivatives, sulfur oxyacids, and sulfoxides, as thiol surrogates for thioether synthesis. This review highlights recent advancements in deoxygenative thioether synthesis, categorizing them by reaction types, including cross-coupling reactions, C-H functionalization, and hydro/halo/oxy-thiolation of unsaturated hydrocarbons. We also discuss representative mechanisms to provide a comprehensive understanding of these innovative approaches.
Supramolecular Chemistry: An Enabling Tool for Asymmetric Catalysis
Authors: Cunningham Laura
Published: January 2025

Asymmetric synthesis and supramolecular chemistry are cornerstones of modern organic chemistry. The combination of both fields to develop new approaches to enantioselective catalysis has gained considerable momentum in recent years. Herein, we highlight some of the advantages offered by various supramolecular architectures over conventional chiral catalysts and reflect on obstacles that currently limit widespread use of supramolecular tools in asymmetric synthesis.

1 Introduction

2 Discussion

2.1 Macrocycles

2.2 Surfactants

2.3 Metal-Organic Cages and Frameworks

2.4 Covalent Organic Frameworks

2.5 DNA

2.6 Mechanically Interlocked Molecules

3 Summary and Outlook
Asymptomatic and Unnoticed Intra-articular Screw Over 18 Years after Fracture of the Posterior Wall of the Acetabulum – A Question of Stability?
Authors: Audretsch Christof K. , Schmidutz Florian , Küper Markus Alexander
Published: January 2025

Fractures of the posterior wall of the acetabulum occur in a frequency of 25–30%. Multifragmentary fractures involving 40–50% of the acetabular surface, the quality of reduction as well as involvement of cartilage and acetabular labrum are considered to have an impact on the development of a reduced posterior stability of the hip joint. This results in a shift of the main weight bearing area with development of a posttraumatic osteoarthritis. In the presented case, a 42-year old male patient was operated on 18 years ago due to a posterior acetabular wall fracture. Retrospectively, one of the screws was located partially intraarticular. However, the patient was asymptomatic over the 18-year period. The first consultation was due to unspecific symptoms of osteoarthritis of the right hip joint especially during flexion and external rotation. Due to only mild radiological signs of osteoarthritis, we indicated only the removal of the intraarticular screw. The symptoms postoperatively switched to a feeling of instability, so a total hip arthroplasty was performed. Since the operation, the patient is asymptomatic regarding the hip joint. The intraarticular screw seemed to stabilize the hip joint. This case demonstrates the importance of a good posterior guidance for the stability of the hip joint on one hand. On the other hand, it demonstrates the minor stress load of the posterior acetabular region, especially after fracture of the posterior wall. Therefore, a good posterior guidance should be one major aim of treatment of posterior acetabular wall fractures.
Dams, development and disposability: Eco-anxiety, precarity and submerging voices in Na. D’souza’s Dweepa
Authors: Karmakar Goutam
Published: January 2025

The construction of large dams in India has faced criticism for its neo-colonial and capitalist practices. This highlights the importance of accountability, the consequences of development discourse, and the tangible impacts on the lives of those affected by dams, development initiatives, displacement, and denial of compensation. The pursuit of large-scale construction projects frequently promotes a conspicuous consumerist perspective, disregarding both marginalised groups and the ethics of sustainable development. The absence of ethical considerations such as empathy, inclusion, and egalitarian ideology in the development narrative often leads to the devaluation of certain lives while prioritising the safety and security of others. Within this particular setting, it is important to recognise the trajectories of those whose lives are considered disposable. In this context, the article scrutinizes Na. D’souza’s novella Dweepa, delving into the experiences of individuals who have faced eco-anxiety, precariousness, and vulnerability, ultimately culminating in their tragic demise due to the construction of the Linganamakki dam over the Sharavathi river.
Intense electromagnetic radiation heating of electrons of a superconductor in the resistive state
Authors: Gershenzon E. M. , Gol’tsman G. N. , Elant’ev A. I. , Karasik B. S. , Potoskuev S. E.
Published: January 2025

The effect of intense millimeter and submillimeter radiation on thin and narrow niobium films in the resistive state is studied. It is shown that the excess resistance emerging due to radiation, as well as the dependence of relaxation time of the resistance on radiation intensity and transport current can be attributed to heating of the electrons. The experimental results are found to be in quantitative agreement with the model of uniform heating of electrons.
Analysis of coupled acoustic and drift modes leading to modons in Maxwellian and non-Maxwellian dusty plasma
Authors: Ehsan Zahida , Batool Nazia , Lashkin V. M.
Published: January 2025

Linear and nonlinear acoustic and drift waves in a confined inhomogeneous dusty plasma are investigated here. We examine two distinct scenarios that correspond to slow and fast temporal dynamics. The dust particles are inert in the first scenario, but actively participate in the dynamics in the second. Accordingly, we distinguish between the coupled dust-modified ion-acoustic and drift waves and coupled ultra-low-frequency dust acoustic and dust drift waves. The corresponding dispersion relations were determined in both situations by using linear analysis. In addition, nonlinear coherent structures known as “modons” or dipole vortices (cyclone–anticyclone pairs) have been identified in both circumstances, along with modons of higher orders. Moreover, as space observations of particle velocity distributions show the presence of either suprathermal tails or shoulders at low energy, we also expand our study for a special example of non-Maxwellian (Kappa and Cairns) dusty plasma. Numerical analysis shows the formation of vortices is impacted by nonthermality. The astrophysical and laboratory contexts provide a useful perspective on the significance of this analysis.
Tunable piezoresistivity for sensors with antiferromagnetic pure Cr and Cr-rich alloy thin films: Cr–V, Cr–W, Cr–Mn
Authors: Schwebke S. , Schultes G.
Published: January 2025

Sputter-deposited thin films of pure chromium and chromium-rich alloys with V, W, and Mn are evaluated in terms of electrical resistivity and piezoresistivity, as measured by the gauge factor, from room temperature to 470 °C. The alloying elements vanadium, tungsten, and manganese, are known to either stabilize or destabilize the spin-density wave antiferromagnetism found in Cr. In a concentration series and a substrate bias voltage series, the variation of resistivity, gauge factors (of up to 20), and their temperature coefficients is shown. High-temperature resistivity measurements indicate increased Néel transition temperatures that are related to a gauge factor maximum. Generally, the gauge factor increases toward the Néel temperature. The Cr60Mn40 film, however, has a small negative temperature coefficient of the gauge factor. This is a desired property in strain and pressure sensor films, as it allows for compensating the temperature coefficient of the elastic modulus of aluminum or steel transducers. An analysis of the resistance change through mechanical loading quantifies Néel temperature changes of up to 100 K per percent of strain that are likely the mechanism of the observed piezoresistivity. Overall, the Cr-rich alloy thin films represent a class of metallic piezoresistive films with properties that can be well adjusted to the sensor application by concentration and sputtering parameters.
Jet characteristics of multiple oil droplets impinging process under the influence of micro-bubbles
Authors: Zheng Nan , Tong Baohong , Zhang Guotao , Wang Zhaochang , Wang Wei , Liu Kun
Published: January 2025

In the process of oil–gas micro-lubrication, the lubricant oil liquids are disturbed by high-speed airflow and are prone to forming oil droplets containing micro-bubbles. Micro-bubbles have a significant influence on the kinetic characteristics of successive/synchronous oil droplet impingement on an oil film and its oil film formation mechanism. Numerical simulations of successive/synchronous oil droplet impinging oil film behavior are based on the coupled level set-volume fraction (CLSVOF) method. The effect of micro-bubbles on the flow dynamics characteristics of the successive/synchronous impinge oil film of double oil droplets is investigated. To investigate the mechanism of jet formation during the impingement process, the law of micro-bubbles influences the formation process of the central and neck jets and their morphology is analyzed. The results show that when micro-bubbles exist, the oil droplet impingement process produces the central jet phenomenon. During successive impingements, the micro-bubble is in the pilot or trailing oil droplet, respectively, and there is a large difference in the jet mechanism generated by these two cases. The energy loss in the successive impingement process is larger when the micro-bubble is inside the pilot oil droplet. The central jet hurts the velocity discontinuity effect of the fluid inside the oil film and plays an inhibiting role in the growth of the crown splash. When the micro-bubble is only within the trailing oil droplet, then the surface tension effect excited by the impingement between the subsequent oil droplet and the flat fluid surface inside the impingement crater will cause a transient sudden reduction in the inner diameter size of the crown splash. During the synchronous impingement, the symmetric micro-bubble impinge mode has a positive effect on both the final horizontal expansion inner diameter of the crown splash and its vertical jet height enhancement. The research method of numerical simulation is used in this study. Seven sets of impingement models under the influence of different micro-bubbles are systematically studied and analyzed under the premise of verifying the feasibility of the numerical method. The results of this study can provide theoretical references for the study of the impingement kinetic behavior and film-forming flow mechanism of highly viscous droplets.
Molecular dynamics and machine learning unlock possibilities in beauty design—A perspective
Authors: Xu Yuzhi , Ni Haowei , Zhao Fanyu , Gao Qinhui , Zhao Ziqing , Chang Chia-Hua , Huo Yanran , Hu Shiyu , Zhang Yike , Grovu Radu , He Hermione , Zhang John Z. H. , Wang Yuanqing
Published: January 2025

Computational molecular design—the endeavor to design molecules, with various missions, aided by machine learning and molecular dynamics approaches—has been widely applied to create valuable new molecular entities, from small molecule therapeutics to protein biologics. In the small data regime, physics-based approaches model the interaction between the molecule being designed and proteins of key physiological functions, providing structural insights into the mechanism. When abundant data have been collected, a quantitative structure–activity relationship can be more directly constructed from experimental data, from which machine learning can distill key insights to guide the design of the next round of experiment design. Machine learning methodologies can also facilitate physical modeling, from improving the accuracy of force fields and extending them to unseen chemical spaces to more directly enhancing the sampling on the conformational spaces. We argue that these techniques are mature enough to be applied to not just extend the longevity of life but the beauty it manifests. In this Perspective, we review the current frontiers in the research and development of skincare products, as well as the statistical and physical toolbox applicable to addressing the challenges in this industry. Feasible interdisciplinary research projects are proposed to harness the power of machine learning tools to design innovative, effective, and inexpensive skincare products.
Combustion modes and oscillation characteristics in a rocket-dominated scramjet
Authors: Tian Zhaoyang , Zhao Guojun , Zhang Xu , Fu Anxiang , Shi Lei
Published: January 2025

To investigate the combustion modes and the corresponding oscillation characteristics in various operational states of a rocket-dominated scramjet, ground direct-connect experiments are carried out. CH* chemiluminescence images, time-frequency analysis, and pressure distributions are employed. The impact of factors, including the MFR (mass flow rate ratio of secondary fuel to the rocket) and the relative position of the secondary fuel injection to the rocket plume, on the combustion and flow process in the rocket-dominated scramjet is obtained. The results indicate that: (i) Three combustion modes are identified in the rocket-dominated scramjet. The cavity stabilized combustion mode is observed in the “rocket-off” case. The combustion exhibits the cavity assisted plume stabilized combustion mode while the MFR is 0.7 in the “rocket-on” case. Reducing the MFR to 0.3 transforms the combustion to the plume stabilized combustion mode. (ii) The cavity assisted plume stabilized combustion mode intensifies the low-frequency oscillations (below 150 Hz), particularly in the fuel combustion region and the region influenced by backpressure, while suppressing oscillations of higher frequency (beyond 300 Hz) presented in the cavity stabilized combustion mode. (iii) The plume stabilized combustion mode effectively inhibits low-frequency oscillations, including reducing both the oscillation frequency range and the oscillation energy. However, the plume stabilized combustion mode based on a high-mass-flow rate rocket exhibits oscillations of higher frequency (ranging from 300 to 400 Hz) in the fuel-burning region at the tail of the plume. (iv) Positioning the fuel injector upstream of the plume enhances the overall flow stability, which significantly suppresses low-frequency oscillations in the cavity.
Spatiotemporal reconstruction of unsteady bridge flow field via hierarchical graph neural networks with causal attention
Authors: Cai Chenzhi , Xiao Jun , Zou Yunfeng , He Xuhui
Published: January 2025

When calculating the transient flow around a bridge structure, traditional computational fluid dynamics methods are extremely time-consuming, especially for multiparameter optimization analyses. Inspired by the development of deep graph neural networks with a mesh structure, this paper describes a spatiotemporal prediction framework for the rapid reconstruction and prediction of transient flows on large-scale unstructured grids. To ensure stability and reliability during self-supervised training, a causal self-attention mechanism is employed in the temporal model. The framework is trained and tested on a dataset containing 40 000 snapshots of bridge flow fields with Reynolds numbers ranging from 104 to 105. The relative mean square error of the model in predicting the velocity and pressure fields is found to be in the order of 10−3 and the relative error does not exceed 10%. This demonstrates that the model is capable of reconstructing high-dimensional flow field information from low-dimensional data. Furthermore, the proposed model achieves a computational speedup by two orders of magnitude compared with traditional computational fluid dynamics methods with respect to the temporal inference. To validate its ability to infer bridge aerodynamic characteristics, the model is used to predict the bridge surface pressure, aerodynamic coefficients, streamlines, and vorticity. The results demonstrate that the proposed model has reliable accuracy, representation, and stability in predicting bridge flow fields and identifying multiscale characteristics.
Hydrodynamic performance of a highly-skewed propeller in ventilated flow conditions near the free surface
Authors: Hasan Ahmad Darori , Lin Yu-Hsien
Published: January 2025

This study investigates the performance of the INSEAN E1619 propeller—a seven-bladed generic submarine propeller designed by Consiglio Nazionale delle Ricerche–Istituto Nazionale per Studi ed Esperienze di Architettura Navale (CNR-INSEAN), the Italian Ship Model Basin—under near-surface conditions through experimental and numerical approaches. Experiments were conducted for semi-submersion and full-submersion scenarios at varying water depths to evaluate how proximity to the water surface influences propeller performance. Additionally, numerical simulations employed a Large Eddy Simulation model combined with a dynamic mesh technique. A two-phase flow, simulated with the Volume of Fluid method, provided insight into free surface effects, with a User-Defined Function governing the propeller's forward motion. A sensitivity analysis of the propeller model was performed using simultaneous grid and time refinement, validated against open-water test results obtained from the National Cheng Kung University towing tank. The simulation results indicated reductions in thrust and torque as the propeller approached the water surface. The ventilation effect was particularly pronounced at lower immersion ratios (hi) and advance coefficients (J). Subsequently, the combined effects of varying propeller immersion ratios (hi) and advance coefficients (J) on hydrodynamic performance and the flow structure around the propeller were thoroughly investigated.
Inclination and rolling effects on water-steam flow instability in residual heat removal pipe
Authors: Shi Mingxuan , Duan Zhongdi , Xue Hongxiang
Published: January 2025

Small modular reactors are increasingly being utilized on offshore platforms as part of the transition to low-carbon energy. A crucial safety system component is the passive residual heat removal system, which effectively eliminates residual heat from the reactor core during power failures. The process of residual heat removal involves direct contact condensation of steam, leading to various flow instabilities, such as subcooled-water reverse flow, Kelvin–Helmholtz instability, and condensation-induced water hammer (CIWH). Marine motions introduce additional complexity to these instabilities. This study developed a rolling experimental setup to simulate an offshore residual heat removal system featuring adjustable inlet steam mass flux, a visualizable rolling test section, and a temperature-controlled water tank. Experiments were conducted with subcooled-water at 30 °C under two steam mass fluxes of 15 and 11 kg/h across 22 scenarios, including horizontal, inclined, and rolling configurations. Visual results show that a liquid column formed by subcooled-water reverse flow is necessary for CIWH. The liquid column's motion is modulated by condensation driving force, flow inertial force, and gravity. In downward-inclined pipes, gravity limits the reverse flow distance, with CIWH typically occurring when subcooled-water floods the pipe. Conversely, the reverse flow distance increases in upward-inclined and rolling pipes, raising flow instability frequency. At 11 kg/h, the flow pattern in the upward-inclined and low-frequency rolling pipes shifts to intermittent slug flow. The bubbles condense during the flow process, and the low subcooling at the interface slows the shrinkage rate, which prevents CIWH.
Boiling bubble behaviors of fluids of different surface tensions on heating surfaces with micro/nanostructures
Authors: Yin Liaofei , Zhang Kexin , Qin Tianjun , Ma Wenhao , Jia Li
Published: January 2025

The use of environmentally friendly coolants with low surface tension in boiling applications holds great promise, and the implementation of micro/nanostructures is widely regarded as an effective strategy for enhancing boiling heat transfer. However, as a critical factor influencing the boiling process, the understanding of boiling bubble behavior on micro/nanostructured modified surfaces remains insufficient for the low surface tension fluids. SF-33, with its zero ozone depletion potential and extremely low global warming potential, is gradually gaining attention in the field of boiling as a representative low-surface-tension fluid. Herein, several copper heating surfaces with micro or micro/nanocomposite structures were fabricated using sintering copper mesh and thermal oxidation techniques. The bubble growth and departure phenomena during pool boiling of coolants SF-33 and de-ionized water on these micro/nanostructured surfaces were investigated and comparatively analyzed. The saturated pool boiling experiments were conducted at atmospheric pressure. It was observed that on smooth flat surface and sintered wire-mesh flat surface, SF-33 bubbles exhibited a faster growth rate, higher departure frequency, and smaller departure diameter. However, on the sintered wire-mesh flat surface with nanowires, de-ionized water bubbles demonstrated a higher departure frequency, while the growth rate and departure diameter were similar to those of SF-33 bubbles. In addition, it was found that the influence of microstructures on de-ionized water bubble behaviors is significantly lower than that of micro/nanocomposite structures, while for SF-33, increasing the microstructures alone can greatly affect bubble growth and departure, with further changes induced by the addition of nanostructures being relatively minor.
The evaporation characteristics and molecular cluster variation of diesel droplets in supercritical environment
Authors: Hu Quan , Li Ruina , Yang Dahai , Liu Feifan , Liu Qingcheng , Yue Hua , Meng Yang
Published: January 2025

In the fuel injection phase of a diesel engine, the temperature and pressure within the cylinder surpass the fuel's critical point, entering a supercritical state. This condition significantly affects the fuel's evaporation and atomization processes within the cylinder. This study conducted an evaporation experiment on diesel droplets under supercritical conditions using a high-temperature, constant-volume droplet evaporation apparatus. A molecular dynamics model was developed to simulate the evaporation of diesel droplets in a nitrogen environment, composed of a mixture of two components: 85.1 mol. % n-dodecane and 14.9 mol. % isooctane. The study focused on the evaporation process in a sub-supercritical environment, analyzing the changes in molecular clusters near the interface during droplet evaporation to elucidate the relationship between droplet evaporation and these molecular clusters. The findings indicate that the lifetime of the droplets decreases with rising ambient temperature and pressure, with the effects being more pronounced in a subcritical environment. The enrichment of nitrogen molecules is 40% in the subcritical environment and 164% in the supercritical environment, suggesting that the enrichment phenomenon of nitrogen molecules is more pronounced under supercritical conditions. At supercritical temperatures, the ambient temperature's influence on the droplet evaporation process is primarily through accelerating the initial heating phase of the droplet. An increase in ambient temperature and pressure leads to a higher number of molecular clusters. The study proposes five levels of clusters based on the varying number of molecules they contain, with different levels transforming into one another. For each increment in the cluster level, the molecular forces within the clusters increase by approximately 0.025 kcal/mol Å. In subcritical environments, a distinct interface exists between the droplets and atmospheric gas, resulting in fewer molecular clusters. Conversely, in supercritical environments, this clear interface is replaced by an interface layer, which facilitates the formation of numerous, larger molecular clusters.
Gas void fraction and flow pattern transition mechanism in an airlift pump system
Authors: Ren Jianhang , Li Meng , Peng Fusen , Zhu Jingyu , Du Yanlian , Han Xuanhe , Fu Mengdi , Ruan Rongqian , Xiao Jianyu , Shen Yijun
Published: January 2025

Airlift pumps (ALPs) have the advantages of simple structure, easy operation, wide applicability, environmental friendliness, and safety reliability. It plays an important role in the chemical industry and the development of marine resources. The gas–liquid two-phase flow in such devices is similar yet different from those used in applications like nuclear reactor systems and heat pump systems. Research on the key parameter of gas void fraction (GVF) in ALPs is relatively scarce. Therefore, this paper establishes a GVF correlation through the drift-flux model. The experiment was conducted in a vertical pipeline with a total length of 3.245 m and pipe diameter of 0.05 m. The experimental operating conditions included three air inlets, with the submergence ratio ranging from 0.6 to 0.815 and a gas superficial velocity ranging from 0 to 2.5 m/s. A validation was conducted using 315 sets of data under the aforementioned conditions, resulting in a mean percentage error, mean absolute percentage error, and root-mean-square percentage error of 2.37%, 7.82%, and 9.62%, respectively. The comparison and analysis of a large amount of experimental data revealed that the abrupt changes in distribution parameter and drift velocity can accurately reflect and explain the transition and transformation of flow pattern. Furthermore, changing the submergence ratio and the inlet position within a certain range has a minimal effect on the distribution parameter and drift velocity, meaning it has little impact on the distribution of the phases and the relative velocity between the phases.
Characterization of the horizontal gas–liquid two-phase flow patterns using acoustic measurement techniques
Authors: Zhao Nan-Nan , Feng Jian-Jun , Zhu Guo-Jun , Wu Guang-Kuan , Luo Xing-Qi
Published: January 2025

The characterization of gas–liquid two-phase flow patterns is crucial for monitoring stability in industrial applications. However, the impact of these flow patterns on gas–liquid two-phase flow-induced sound (GTFIS) emissions remains inadequately understood. In this paper, the GTFIS signals at high liquid velocities within a horizontal pipe are captured using precision hydrophone. A novel approach for the analysis of acoustic signals that synergistically combines Variational Mode Decomposition, Singular Value Decomposition, and nonlinear signal processing methods is proposed to assess the flow dynamics. The results show that the GTFIS signals exhibit chaotic characteristics. Two distinct Hurst exponents are observed for each acoustic signal: one is greater than 0.5 and the other is less than 0.5. The coexistence of randomly moving small bubbles and intermittent bubbles contributes to an increase in the complexity of the attractor phase trajectory of acoustic signals, resulting in a maximum value in the correlation dimension. The expansion radius and correlation dimension of mesoscale acoustic signals can serve as early warning indicators for the transition from dispersed bubble flow to slug flow. In conjunction with the characteristic parameters of multi-scale entropy, the flow patterns can be effectively characterized.
Performance of the fractional step method with various temporal discretization and adaptive time step size schemes for pulsating ventilation
Authors: Hu Junyao , Wang Haidong , Dai Yuwei , Zhou Pengzhi , Li Jingzhi
Published: January 2025

Pulsating ventilation has been drawing extensive attention recently. Computational fluid dynamics (CFD), as a widely used and effective tool for investigating pulsating ventilation, often consumes significant computation time. To identify a suitable numerical scheme for this circumstance, we adopted the standard incremental pressure-correction (SIPC) method with higher-order temporal discretization schemes to simulate indoor airflow. To further improve the simulation efficiency, two adaptive time step size schemes were proposed and used to simulate both long-period and short-period pulsating ventilation conditions. Results showed that the SIPC scheme offers accuracy comparable to the PISO (pressure-implicit with splitting of operators) algorithm while saving about 40% of computation time. Higher-order temporal discretization schemes have minimal impact on the accuracy and stability of the SIPC scheme for simulating pulsating airflow, with the first-order Euler backward implicit scheme showing slightly higher efficiency. Compared to the conventional fixed time step size scheme (fixed scheme), both adaptive time step size schemes significantly reduce computation time with negligible impact on accuracy. The scheme that controls time step size based on a given maximum Courant number (MaxCo scheme) saves about 35% of computation time, while the scheme that combines a given maximum Courant number with the curvature of the inlet velocity-time curve (MaxCo+K scheme) to control time step size saves nearly 30%. Although the MaxCo+K scheme requires about 10% more computation time than the MaxCo scheme, it improved accuracy by approximately 10% by more accurately capturing the inlet velocity boundary condition in the short-period pulsating ventilation simulation.
The behaviour of an arid zone dasyurid, the kultarr (Antechinomys laniger), in captivity
Authors: Stannard Hayley J. , Goodchild Lisa M. , Old Julie M.
Published: January 2025

Understanding behaviour of threatened animal species is an important component of conservation. This study assessed video and recorded data collected on a historical captive population of kultarrs (Antechinomys laniger) to describe their behaviour in captivity. The kultarr, a small marsupial in the Dasyuridae family, is native to central Australia. It is categorised as Least Concern on the International Union for Conservation of Nature (IUCN) Red List of Threatened Species with its population assessed as decreasing. Here, we describe some key behaviours displayed by kultarrs in captivity, including grooming, nest building and use of shelter, predatory and feeding behaviour, and social behaviour. Gaining an understanding of kultarr behaviour in captivity will enhance and improve captive management of the species and provide insights into how kultarrs may behave in the wild.
What can emotion and abstract words tell us about context availability ratings?
Authors: Mason Catherine Jane , Hameau Solène , Nickels Lyndsey
Published: January 2025

Semantic dimensions such as context availability, imageability and valence, form core components of many
theoretical accounts of lexical processing. Typically, normative data for such semantic dimensions are drawn from subjective
ratings, however, questions have been raised regarding the reliability and validity of these ratings. In this paper, we discuss
this issue with a focus on context availability norms. Using data collected for another study, we show that context availability
ratings required significantly higher rates of data exclusions at the level of both participants and items compared to other
variables. In addition, high standard deviations at the item level, indicated a substantial degree of disagreement between
participants. This suggested that some participants may have had difficulty understanding the concept of context availability
which hindered their ability to complete the ratings. We provide recommendations for future research focusing on context
availability and for norm collection procedures more broadly in order that the validity of such norms can be improved. In
particular, we suggest that clear guidelines are required for data cleaning in order that the reliability of such norms is
maximised and to facilitate replication across studies.
Gaussian orbital perturbation theory in Schwarzschild space-time in terms of elliptic functions
Authors: Yanchyshen Oleksii , Lämmerzahl Claus
Published: January 2025

General relativistic Gauss equations for osculating elements for bound orbits under the influence of a perturbing force in an underlying Schwarzschild space-time have been derived in terms of Weierstrass elliptic functions. Thereby, the perturbation forces are restricted to act within the orbital plane only. These equations are analytically solved in linear approximation for several different perturbations such as cosmological constant perturbation, quantum correction to the Schwarzschild metric, and hybrid Schwarzschild/post-Newtonian 2.5 order self-force for binary systems in an effective one-body framework.