bluuebunny/crossref_metadata_2025 huggingface dataset:
Spin characteristics in conjugated stable diradicals
Authors: Dai Dacheng , Zhan Qian , Shi Tianfang , Wang Dongsheng , Zheng Yonghao
Published: July 2024

The burgeoning interest in stable conjugated diradicals is attributed to their distinctive spin characteristics. In this review, we emphasize how to precisely control these spin characteristics to understand their role in the molecules and as functional radical materials.
Detection of diheptacendiyl diradical intermediate in the cycloreversion of diheptacene to heptacene
Authors: Wagner Marie S. , Peisert Heiko , Chassé Thomas , Bettinger Holger F.
Published: July 2024

The diheptacendiyl diradical forms during the thermal [π4s + π4s] cycloreversion of diheptacene.
Dye adsorption performance of an anionic Cd2+ MOF material based on semi-rigid hexacarboxylic acid
Authors: Xiong Yuxuan , Li Dan-Dan , Yu Jie-Hui , Yang Qingfeng
Published: July 2024

A new anionic MOF material was synthesized, and its degradation performance towards dyes was investigated.
Competition of intermolecular interactions in the self-assembly of co-crystals of trifluoro-meta-arylenediamines (benzene, nitrobenzene, pyridine) with 12-, 15-, and 18-membered crown ethers
Authors: Vaganova Tamara , Gatilov Yurij , Kryuchkova Natalia , Pishchur Denis , Malykhin Evgenij
Published: July 2024

Arylenediamine acceptor properties and crown ether size affect the stoichiometry and supramolecular structure of co-crystals by means of restructuring of guest–host and guest–guest contacts, changing packing enthalpies and bonding energies.
Chemical bonding misnomer in AeF− (Ae = Be–Ca) anions
Authors: Guha Ankur K.
Published: July 2024

No dative bonds are there in AeF (Ae = Be–Ca) anions.
Correction: Simple, accurate, adjustable-parameter-free prediction of NMR shifts for molecules in solution
Authors: Hoyt Emlyn M. , Smith Lachlan O. , Crittenden Deborah L.
Published: July 2024

Correction for ‘Simple, accurate, adjustable-parameter-free prediction of NMR shifts for molecules in solution’ by Emlyn M. Hoyt et al., Phys. Chem. Chem. Phys., 2023, 25, 9952–9957, https://doi.org/10.1039/D3CP00721A.
Eco-friendly porous composite of octaphenyl polyhedral oligomeric silsesquioxane and HKUST-1 with hydrophobic–oleophilic properties towards sorption of oils and organic solvents
Authors: Dharmaraj Kanakarasu , Sanjay Kumar Mohandas , Palanisami Nallasamy , Prakash Muthuramalingam , Loganathan Pushparaj , Shanmugan Swaminathan
Published: July 2024

A robust, non-toxic and hydrophobic–oleophilic Ph-POSS@HKUST-1 is synthesized by incorporation of hydrophobic Ph-POSS into hydrophilic HKUST-1. The developed Ph-POSS@HKUST-1 is an effective and reusable sorbent for oils and organic solvents.
Selenoprotein H mediates low selenium-related cognitive decline through impaired oligodendrocyte myelination with disrupted hippocampal lipid metabolism in female mice
Authors: Lv Qingqing , Yang Aolin , Han Ziyu , Yu Ruirui , Zhu Junying , Shi Zhan , Yang Chenggang , Dai Shimiao , Hao Mengru , Chen Yuqing , Zhou Ji-Chang
Published: July 2024

This study utilizing Selenoh gene knockout mice identified that Selenoh mediates low selenium-related cognitive decline in female mice, an effect attributed to impaired oligodendrocyte myelination with disrupted lipid metabolism in the hippocampus.
Regulatory effect of β-glucan secreted by Rhizobium pusense on triglyceride metabolism and their relationships with the modulation of intestinal microbiota in mice fed a high-fat diet
Authors: Zhang Bin , Zhao Wei , Song Dong , Lyu Xiaomei
Published: July 2024

β-Glucan could activate the hepatic AMPK signaling pathway by regulating the gut microbiota and metabolites through gut–liver crosstalk, exerting a lipid-lowering effect in mice fed a high-fat diet and improving obesity.
Four novel anti-adhesive activity peptides against Helicobacter pylori derived from rice bran protein: release, identification and anti-adhesive mechanisms elucidation
Authors: Li Guanlong , Miao Zhengfei , Liu Xiaolan , Wang QuanXin , Zheng Xiqun
Published: July 2024

Four novel anti-adhesive activity peptides against Helicobacter pylori derived from rice bran protein were found.
Scalable and adaptable two-ligand co-solvent transfer methodology for gold bipyramids to organic solvents
Authors: Coplan Caitlin D. , Watkins Nicolas E. , Lin Xiao-Min , Schaller Richard D.
Published: July 2024

Gold bipyramids, which require alkylammonium synthetic ligands to form, resist routes to ligand exchange. Here we use both a co-solvent and combination of ligands that together yield successful phase transfer of this high surface area nanostructure.
Polarized luminescence in single upconversion NaYbF4:Er rods
Authors: Leontyev Andrey V. , Nurtdinova Larisa A. , Mityushkin Evgeny O. , Shmelev Artemi G. , Zharkov Dmitry K. , Chuklanov Anton P. , Nurgazizov Niaz I. , Nikiforov Victor G.
Published: July 2024

Rare earth-doped micro/nano-crystals are promising as microscopic fluorescent probes for monitoring local environment parameters, particularly for orientation tracking.
Exploring ssDNA translocation through α-hemolysin using coarse-grained steered molecular dynamics
Authors: Okyay Cagla , Dessaux Delphine , Ramirez Rosa , Mathé Jérôme , Basdevant Nathalie
Published: July 2024

Coarse-Grained Steered Molecular Dynamics (SMD) have proven to be successfull to study single-stranded DNA (ssDNA) translocation through biological nanopores, especially alpha-hemolysin (αHL).
Palladium nanoparticle catalyzed synthesis of indoles via intramolecular Heck cyclisation
Authors: Sarmah Debasish , Choudhury Anup , Bora Utpal
Published: July 2024

The palladium(ii)-PEG 400 system offers efficient synthesis of indoles from N-vinyl and N-allyl-2-haloanilines, showcasing high activity and reusability due to in situ Pd nanoparticle generation.
Integrating encapsulation and self-assembly-induced disulfide cross-linking: a universal strategy for preparing hydrophilic guest-loaded responsive hyperbranched polyglycerol nanogels
Authors: Zeng Hai , Chen Qingli , Zhou Li
Published: July 2024

We report a universal method for preparing hydrophilic guest-loaded responsive nanogels (NGs) by combining the encapsulation advantages of amphiphilic HPG-LA with its capability to form NGs by self-assembly-induced disulfide cross-linking.
Well-defined poly(2-isopropenyl-2-oxazoline) brushes provide fouling resistance and versatility in surface functionalization
Authors: Singh Manisha , Poláková Lenka , de los Santos Pereira Andres , Pop-Georgievski Ognen , Svoboda Jan , Riedel Tomáš , Gupta Sachin , Sedláková Zdeňka , Raus Vladimír , Poręba Rafał
Published: July 2024

Well-defined poly(2-isopropenyl-2-oxazoline) brushes are prepared via aqueous Cu(0)-RDRP under optimized conditions and their high resistance against non-specific protein fouling and versatility in surface functionalization are demonstrated.
Green synthesis of silver nanoparticles from Manilkara zapota leaf extract for the detection of aminoglycoside antibiotics and other applications
Authors: Sahu Khushboo , Kurrey Ramsingh , Pillai Ajai Kumar
Published: July 2024

Antibiotics of aminoglycoside (AMG) class, such as streptomycin (STR), have been widely used to treat infectious diseases caused by Gram-negative bacteria in livestock and humans.
Phytofabricated ZnO-NPs mediated by Hibiscus tiliaceus leaf extract and its potential as a diosgenin delivery vehicle
Authors: Putri Oktavina Kartika , Rahayu Lina Oktavia , Kusumawati Yuly , Fadlan Arif , Subagyo Riki , Santoso Mardi
Published: July 2024

Diosgenin can overcome multiple health disorders but has low solubility in water. Zinc oxide nanoparticles (ZnO-NPs) have provided promising potential in the biomedical field and were successful as a carrier for increasing the diosgenin's solubility.
Lead-free iron-doped Cs3Bi2Br9 perovskite with tunable properties
Authors: Htun Thiri , Elattar Amr , Elbohy Hytham , Tsutsumi Kosei , Horigane Kazumasa , Nakano Chiyu , Gu Xiaoyu , Suzuki Hiroo , Nishikawa Takeshi , Kyaw Aung Ko Ko , Hayashi Yasuhiko
Published: July 2024

The bandgap of lead-free, non-toxic Cs3Bi2Br9 perovskite material is reduced from 2.54 eV to 1.78 eV by changing the crystal structure to Cs3Bi2−xFexBr9, Cs2Bi1−xFexBr5, and CsFeBr4, depending on the varying Fe doping concentrations.
Synthesis and evaluation of sulfonamide derivatives of quinoxaline 1,4-dioxides as carbonic anhydrase inhibitors
Authors: Buravchenko Galina I. , Scherbakov Alexander M. , Krymov Stepan K. , Salnikova Diana I. , Zatonsky George V. , Schols Dominique , Vullo Daniela , Supuran Claudiu T. , Shchekotikhin Andrey E.
Published: July 2024

A series of sulfonamide derived quinoxaline 1,4-dioxides were synthesized and evaluated as inhibitors of carbonic anhydrases with antiproliferative potency.
Switchable molecular electrocatalysis
Authors: Dutt Shifali , Kottaichamy Alagar Raja , Dargily Neethu Christudas , Mukhopadhyay Sanchayita , Nayak Bhojkumar , Devendrachari Mruthyunjayachari Chattanhali , Vinod Chatakudhath Prabakaran , Nimbegondi Kotresh Harish Makri , Ottakam Thotiyl Musthafa
Published: July 2024

Demonstration of a switchable electrocatalysis mechanism modulated by hydrogen bonding interactions in ligand geometries.
Nickel-catalyzed regiodivergent sulfonylarylation of 1,3-enynes to access allenes and dienes
Authors: Chi Zhuomin , Zhou Yongchao , Liu Bingbing , Xu Xiaojing , Liu Xueyuan , Liang Yongmin
Published: July 2024

The radical-mediated difunctionalization of 1,3-enynes facilitates rapid access to structurally diverse allenes and dienes.
In situ metallization of 2D COFs with acid/base site synergistic effects for boosting one-pot CO2 conversion
Authors: Yu Yi , Wang Meng , Wu Ying , Xi Hongxia
Published: July 2024

Metal-functionalized 2D COFs synthesized through an in situ metallization method were used as efficient heterogeneous catalysts in the one-pot conversion of olefins and CO2 into cyclic carbonates.
Spatial decoupling strategy boosted alkaline hydrogen evolution for an efficient solar-driven AEM electrolyzer
Authors: Cui Minghui , Zhou Yansong , Guo Rongjing , Zhao Wenqi , Liu Yanjing , Ou Qiongrong , Zhang Shuyu
Published: July 2024

Substrate modification achieves spatial decoupling of the hydrogen evolution reaction process, thereby greatly improving the efficiency and stability of the catalyst.
Homologous heterostructures of Ni/NiFeO Mott–Schottky for alkaline water electrolysis
Authors: Liu Manna , Yang Hua , Zhou Zihao , Zhao Yingxia , Yuan Jinkai , Peng Shaomin , Sun Ming , Yu Lin
Published: July 2024

An in situ strategy is proposed to fabricate a Mott–Schottky Ni/NiFeO catalyst composed of Ni nanoparticles over NiFeO nanosheets, which leads to charge transfer from Ni to Fe and promotes the bifunctional activity for the HER and OER.
Multimodal effects of an extracellular matrix on cellular morphology, dynamics and functionality
Authors: Chen Xin , Liu Wenhao , Su Chi , Shan Jianyang , Li Xiang , Chai Yimin , Yu Yaling , Wen Gen
Published: July 2024

Multimodal analysis of the effects of cdECM biomaterials with different topological morphologies on chondrocyte morphologies, dynamics and functionality.
Integrated design and application of stimuli-responsive metal–organic frameworks in biomedicine: current status and future perspectives
Authors: Liu Hao , Xing Fei , Yu Peiyun , Shakya Sujan , Peng Kun , Liu Ming , Xiang Zhou , Ritz Ulrike
Published: July 2024

Various stimuli-responsive MOFs require different triggers and exhibit diverse applications, necessitating the development of biomedical application strategies tailored to specific environments.
Enhancing spleen-targeted mRNA delivery with branched biodegradable tails in lipid nanoparticles
Authors: Ren Yupeng , Zeng Ling , Tang Yingsen , Liao Jing , Jiang Meng , Cao Xinxiu , Fan Hui , Chen Jinjin
Published: July 2024

Ionizable lipids with branched tails enhance the selective mRNA delivery to spleen, particularly to antigen-presenting cells.
Precise molecular design for a twisted pyrene-thiophene based mechanofluorochromic probe with large Stokes shift and feasibility study towards security ink and re-writable papers
Authors: Bhatta Ram Prasad , Sumit  , Kachwal Vishal , Vishwakarma Vandana , Roy Choudhury Angshuman , Laskar Inamur Rahaman
Published: July 2024

Pyrene-thiophene based AIEE active probe molecules with excellent solvatochromism (Δλ, ∼145 nm) along with a multicolor reversible MFC properties for security ink and re-writable papers
A robust predictive control scheme for uncertain continuous‐time delayed systems under actuator saturation
Authors: Ghaffari Valiollah
Published: July 2024

This paper concentrates on synthesizing robust predictive controllers in uncertain models with time‐delay and saturated input. To handle the complexities simultaneously and reach the desired objective, a state‐feedback structure with unknown gains is considered the compensator. Then, to specify the instantaneous values of the regulator's gains, an optimization issue will be derived relying on linear matrix inequality. Accordingly, in uncertain continuous‐time systems with some constraints and time‐delays, the controller's coefficients would be found in an online way from such an optimization. Numerous continuous‐time simulations are numerically performed to reveal the merit and robustness of the suggested methodology over similar techniques.
Multi‐objective terminal trajectory optimization based on hybrid genetic algorithm pseudospectral method
Authors: Qiu Jiaduo , Xiao Shaoqiu
Published: July 2024

During terminal guidance, the attack platform is provided with a high‐resolution image of the target area through the application of synthetic aperture radar. Additionally, the stealth trajectory with low observability can significantly impact mission success. This paper considers both the performance of missile‐borne synthetic aperture radar imaging and stealth performance as influencing factors for terminal trajectory optimization, which is modelled as a constrained multi‐objective optimization problem. The application of the pseudospectral method in the solution of optimal control problems has led to the proposal of the hybrid genetic algorithm pseudospectral optimization framework. The problem is decomposed into several single‐objective optimal control problems, which can generate a specific initial population for the genetic algorithm to obtain a set of Pareto‐optimal solutions. Finally, the numerical simulations demonstrate the effectiveness of the proposed optimization approach compared with the benchmark scheme.
Time‐domain harmonic source location and evaluation methods based on non‐linear and time‐varying properties of devices
Authors: Zhang Chenhao , Li Yang , Han Wei , Song Guobing , Zhang Hua
Published: July 2024

Most of the existing methods for harmonic analysis are from frequency‐domain perspective. In fact, the essential factor for generating harmonics is non‐linear characteristic or time‐varying property. Therefore, the harmonic generation mechanism and the harmonic source location method are investigated from the time domain perspective in this paper. Firstly, a general model of non‐harmonic sources is established. The non‐harmonic sources will match well with the proposed general model while the harmonic source will not. Then correlation coefficient that reflects compliance degree between each device and the general model is defined for distinguishing harmonic sources from non‐harmonic sources. On this basis, a novel time‐domain harmonic source location method is proposed. Numerous simulations and experiments have demonstrated that the proposed method has good performance under fluctuations, saturations, pre‐distortions, transient process, and resonances. The defined correlation coefficient can reflect non‐linearity/time‐varying degree of the harmonic source, which can be used for evaluating harmonic emission level of each harmonic source. On this basis, a simple harmonic responsibility division method is proposed, which is immune to possible fluctuations, pre‐distortions, saturations, resonances, and impedance variation.
Stochastic weather simulation based on gate recurrent unit and generative adversarial networks
Authors: Han Lingling , Fu Xueqian , Chang Xinyue , Li Yixuan , Bai Xiang
Published: July 2024

The weather has a significant impact on power load and power system planning. Stochastic weather simulation is important in the field of power systems. However, due to factors such as long recording years, observation technology, and so on, the historical weather data often have the problem of missing or insufficient. Meteorological data are characterized by changeable, rapid change, and high dimensions. Therefore, it is a challenging task to accurately grasp the law of weather data. This article presents a random weather simulation model based on gate recurrent unit (GRU) and generative adversarial networks (GAN). GRU selectively learns or forgets what was in the previous moment during training; it can learn the previous and current data of the time series data. When combined with the GAN, it will produce data with the same distribution as the original weather data. The proposed method was evaluated on a real weather dataset, and the results show that the proposed method outperforms the other contrast algorithms.
Association of the IceCube neutrinos with blazars in the CGRaBS sample
Authors: Kouch Pouya M. , Lindfors Elina , Hovatta Talvikki , Liodakis Ioannis , Koljonen Karri I. I. , Nilsson Kari , Kiehlmann Sebastian , Max-Moerbeck Walter , Readhead Anthony C. S. , Reeves Rodrigo A. , Pearson Timothy J. , Jormanainen Jenni , Ramazani Vandad Fallah , Graham Matthew J.
Published: July 2024

The origin of high-energy (HE) astrophysical neutrinos has remained an elusive hot topic in the field of HE astrophysics for the past decade. Apart from a handful of individual associations, the vast majority of HE neutrinos arise from unknown sources. While there are theoretically motivated candidate populations, such as blazars – a subclass of active galactic nuclei with jets pointed toward our line of sight – they have not been convincingly linked to HE neutrino production yet. Here, we perform a spatio-temporal association analysis between a sample of blazars (from the CGRaBS catalog) in the radio and optical bands and the most up-to-date IceCube HE neutrino catalog. We find that if the IceCube error regions are enlarged by 1° in quadrature, to account for unknown systematic errors at a maximal level, a spatio-temporal correlation between the multiwavelength light curves of the CGRaBS blazars and the IceCube HE neutrinos is hinted at, least at a 2.17σ significance level. On the other hand, when the IceCube error regions are taken as their published values, we do not find any significant correlations. A discrepancy in the blazar-neutrino correlation strengths, when using such minimal and enlarged error region scenarios, was also obtained in a recent study by the IceCube collaboration. In our study, this difference arises because several flaring blazars – coinciding with a neutrino arrival time – happen to narrowly miss the published 90%-likelihood error region of the nearest neutrino event. For all of the associations driving our most significant correlations, the flaring blazar is much less than 1° away from the published error regions. Therefore, our results indicate that the question of the blazar-neutrino connection is highly sensitive to the reconstruction of the neutrino error regions, whose reliability is expected to improve with the next generation of neutrino observatories.
Burst-recurrence properties revealed with Insight-HXMT and NICER for the newly discovered accreting millisecond pulsar MAXI J1816–195
Authors: Wang P. J. , Chen Y. P. , Ji L. , Zhang S. , Zhang S. N. , Kong L. D. , Chang Z. , Zhang L. , Tao L. , Qu J. L. , Ge M. Y. , Li J. , Peng J. Q. , Shui Q. C. , Li Z. S.
Published: July 2024

We report the results of our analysis of 83 type-I bursts during the 2022 outburst of the newly discovered accreting millisecond pulsar MAXI J1816–195 based on Insight-HXMT and NICER observations. We focus on the burst-recurrence time and its correlation with persistent flux and outburst evolution. The extensive observations of Insight-HXMT and NICER confirm the presence of quasi-periodic thermonuclear bursts during this outburst, with a recurrence time in the range of 1.15–2 h, which varies with the source persistent flux. The burst recurrence times are, in general, longer at comparable flux levels in the outburst rising phase than those in the fading phase, forming an apparent hysteresis phenomenon. These burst properties make MAXI J1816–195 a unique target for investigating the underlying burst-accretion mechanisms. We discuss the plausible explanations for the hysteresis phenomenon, which appears to be related to changes in the ignition condition or accretion geometry during the outburst.
A spatially resolved radio spectral study of the galaxy M 51
Authors: Gajović L. , Adebahr B. , Basu A. , Heesen V. , Brüggen M. , de Gasperin F. , Lara-Lopez M. A. , Oonk J. B. R. , Edler H. W. , Bomans D. J. , Paladino R. , Garduño L. E. , López-Cruz O. , Stein M. , Fritz J. , Piotrowska J. , Sinha A.
Published: July 2024

Context. Radio continuum emission from galaxies at gigahertz frequencies can be used as an extinction-free tracer of star formation. However, at frequencies of a few hundred megahertz, there is evidence for low-frequency spectral flattening.

Aims. We wish to understand the origin of this low-frequency flattening better, and to this end, we performed a spatially resolved study of the nearby spiral galaxy M51. We explored the different effects that can cause a flattening of the spectrum towards lower frequencies, such as free–free absorption and cosmic-ray ionisation losses.

Methods. We used radio continuum intensity maps between 54 and 8350 MHz at eight different frequencies, with observations at 240 MHz from the Giant Metrewave Radio Telescope presented for the first time. We corrected for the contribution from thermal free–free emission using an H α map that was corrected for extinction with 24 μm data. We fitted free–free absorption models to the radio spectra to determine the emission measure (EM) as well as polynomial functions to measure the non-thermal spectral curvature. We also obtained a new extinction-corrected H α intensity map from the Metal-THINGS survey using integral field unit spectroscopy.

Results. The non-thermal low-frequency radio continuum spectrum between 54 and 144 MHz is very flat and even partially inverted, particularly in the spiral arms; in contrast, the spectrum at higher frequencies is typical for a non-thermal radio continuum spectrum. However, we did not find any correlation between the EMs calculated from radio and from H α observations; instead, the non-thermal spectral curvature weakly correlates with the H I gas-mass surface density. This suggests that cosmic-ray ionisation losses play an important role in the low-frequency spectral flattening.

Conclusions. The observed spectral flattening towards low frequencies in M51 is caused by a combination of ionisation losses and free–free absorption. The reasons for this flattening need to be understood in order to use sub-gigahertz frequencies as a tracer of star formation.
The updated BOSZ synthetic stellar spectral library
Authors: Mészáros Szabolcs , Bohlin Ralph , Prieto Carlos Allende , Cseh Borbála , Kovács József , Fleming Scott W. , Dencs Zoltán , Deustua Susana , Gordon Karl D. , Hubeny Ivan , Mező György , Truszek Márton
Published: July 2024

Context. The modeling of stellar spectra of flux standards observed by the Hubble and James Webb space telescopes requires a large synthetic spectral library that covers a wide atmospheric parameter range.

Aims. The aim of this paper is to present and describe the calculation methods behind the updated version of the BOSZ synthetic spectral database, which was originally designed to fit the CALSPEC flux standards. These new local thermodynamic equilibrium (LTE) models incorporate both MARCS and ATLAS9 model atmospheres, updated continuous opacities, and 23 new molecular line lists.

Methods. The new grid was calculated with Synspec using the LTE approximation and covers metallicities [M/H] from −2.5 to 0.75 dex, [α/M] from −0.25 to 0.5 dex, and [C/M] from −0.75 to 0.5 dex, providing spectra for 336 unique compositions. Calculations for stars between 2800 and 8000 K use MARCS model atmospheres, and ATLAS9 is used between 7500 and 16 000 K.

Results. The new BOSZ grid includes 628 620 synthetic spectra from 50 nm to 32 µm with models for 495 Teff−log 𝑔 parameter pairs per composition and per microturbulent velocity. Each spectrum has eight different resolutions spanning a range from R = 500 to 50 000 as well as the original resolution of the synthesis. The microturbulent velocities are 0, 1, 2, and 4 km s−1.

Conclusions. The new BOSZ grid extends the temperature range to cooler temperatures compared to the original grid because the updated molecular line lists make modeling possible for cooler stars. A publicly available and consistently calculated database of model spectra is important for many astrophysical analyses, for example spectroscopic surveys and the determination of stellar elemental compositions.
Small-scale vortical motions in cool stellar atmospheres
Authors: Canivete Cuissa J. R. , Riva F. , Steiner O.
Published: July 2024

Context. Small-scale vortices in the solar atmosphere have received considerable attention in recent years. These events are considered potential conduits for the exchange of energy and mass between the solar atmospheric layers from the convective surface to the corona. Similar events may occur in the atmospheres of other stars and play a role in energy transfer within their atmospheres.

Aims. Our aim is to study the presence and properties of small-scale swirls in numerical simulations of the atmospheres of cool main-sequence stars. Our particular focus is on understanding the variations in these properties for different stellar types and their sensitivity to the surface magnetic field. Furthermore, we aim to investigate the role of these events in the energy transport within the simulated atmospheres.

Methods. We analyzed three-dimensional, radiative-magnetohydrodynamic, box-in-a-star, numerical simulations of four main-sequence stars of spectral types K8V, K2V, G2V, and F5V. These simulations include a surface small-scale dynamo responsible for amplifying an initially weak magnetic field. Thus, we can study models characterized by very weak, or, in near equipartition magnetic fields. To identify small-scale vortices in horizontal layers of the simulations, we employed the automated algorithm SWIRL.

Results. Small-scale swirls are abundant in the simulated atmospheres of all the investigated cool stars. The characteristics of these events appear to be influenced by the main properties of the stellar models and by the strength of the surface magnetic field. In addition, we identify signatures of torsional Alfvénic pulses associated with these swirls, which are responsible for a significant vertical Poynting flux in the middle photospheres of the simulated stellar models. Notably, this flux is particularly significant in the K8V model, suggesting that if ~70% of it is dissipated in the low chromosphere, small-scale vortical motions may play a role in the enhanced basal CaII H and K fluxes observed in the range of B − V color index 1.1 ≤ B − V ≤ 1.4. Finally, we present a simple analytical model, along with an accompanying scaling relation, to explain the peculiar result of the statistical analysis that the rotational period of surface vortices increases with the effective temperature of the stellar model.

Conclusions. Our study shows that small-scale vortical motions are not unique to the solar atmosphere and that their interplay with the stellar surface magnetic field may effect the observable chromospheric activity of main-sequence cool dwarf stars.
The hot circumgalactic medium in the eROSITA All-Sky Survey
Authors: Zhang Yi , Comparat Johan , Ponti Gabriele , Merloni Andrea , Nandra Kirpal , Haberl Frank , Truong Nhut , Pillepich Annalisa , Locatelli Nicola , Zhang Xiaoyuan , Sanders Jeremy , Zheng Xueying , Liu Ang , Popesso Paola , Liu Teng , Predehl Peter , Salvato Mara , Shreeram Soumya , Yeung Michael C. H.
Published: July 2024

Aims. Understanding how the properties of galaxies relate to the properties of the hot circum-galactic medium (CGM) around them can constrain galaxy evolution models. We aim to measure the scaling relations between the X-ray luminosity of the hot CGM and the fundamental properties (stellar mass and halo mass) of a galaxy.

Methods. We measured the X-ray luminosity of the hot CGM based on the surface brightness profiles of central galaxy samples measured from Spectrum Roentgen Gamma (SRG)/eROSITA all-sky survey data. We related the X-ray luminosity to the galaxies’ stellar and halo mass, and we compared the observed relations to the self-similar model and intrinsic (i.e., not forward-modeled) output of the IllustrisTNG, EAGLE, and SIMBA simulations.

Results. The average hot CGM X-ray luminosity (LX, CGM) correlates with the galaxy’s stellar mass (M*). It increases from (1.6 ± 2.1) × 1039 erg s−1 to (3.4 ± 0.3) × 1041 erg s−1, when log(M*) increases from 10.0 to 11.5. A power law describes the correlation as log(LX, CGM) = (2.4 ± 0.1)×log(M*)+(14.6 ± 1.5). The hot CGM X-ray luminosity as a function of halo mass is measured within log(M500c) = 11.3 − 13.7, extending our knowledge of the scaling relation by more than two orders of magnitude. LX, CGM increases with M500c from (3.0 ± 1.6) × 1039 erg s−1 at log(M500c) = 11.3 to (1.3 ± 0.1) × 1042 erg s−1 at log(M500c) = 13.7. The relation follows a power law of log(LX, CGM) = (1.32 ± 0.05)×log(M500c)+(24.1 ± 0.7). Our observations highlight the necessity of non-gravitational processes at the galaxy group scale while suggesting these processes are sub-dominant at the galaxy scale. We show that the outputs of current cosmological galaxy simulations generally align with the observational results uncovered here but with possibly important deviations in selected mass ranges.

Conclusions. We explore, at the low mass end, the average scaling relations between the CGM X-ray luminosity and the galaxy’s stellar mass or halo mass, which constitutes a new benchmark for galaxy evolution models and feedback processes.
The role of active galactic nucleus feedback on the evolution of dwarf galaxies from cosmological simulations
Authors: Arjona-Gálvez Elena , Di Cintio Arianna , Grand Robert J. J.
Published: July 2024

Aims. Recent observational studies suggest that feedback from active galactic nuclei (AGNs) may play an important role in the formation and evolution of dwarf galaxies, an issue that has received little attention from a theoretical perspective.

Methods. We investigated this using two sets of 12 cosmological magnetohydrodynamic simulations of the formation of dwarf galaxies
(108.3M⊙ ≤ M* ≤ 109.8M⊙):

one set using a version of the AURIGA galaxy formation physics model including AGN feedback and a parallel set with AGN feedback turned off.

Results. We show that the full-physics AGN runs satisfactorily reproduce several scaling relations, including the black-hole-to-stellar mass (MBH-M⋆), the black-hole-to-sigma (MBH-σ⋆), and the baryonic Tully-Fisher relation. We find that the global star formation (SF) of galaxies run with an AGN is reduced compared to the one in which the AGN has been turned off, suggesting that AGN feedback is a viable way of suppressing SF in dwarf galaxies, even though none of our galaxies is completely quenched by z = 0. Furthermore, we find a tight correlation between the median SF rates and the MBH/M⋆ ratio in our simulated dwarfs. Star formation is suppressed due to gas heating in the vicinity of the AGN: less HI gas is available in AGN runs, though the total amount of gas is preserved across the two settings within each galaxy. This indicates that the main effect of AGN feedback in our dwarfs is to heat up and push the gas away from the galaxy’s centre rather than expelling it completely. Finally, we show that the two galaxies harbouring the largest supermassive black holes have suffered a considerable (up to ∼65%) reduction in their central dark matter density, pinpointing the role of AGNs in determining the final dark matter mass distribution within dwarf galaxies. This pilot paper highlights the importance of modelling AGN feedback at the lowest mass scales and the impact this can have on dwarf galaxy evolution.
Observational signatures of the dust size evolution in isolated galaxy simulations
Authors: Matsumoto Kosei , Hirashita Hiroyuki , Nagamine Kentaro , van der Giessen Stefan , Romano Leonard E. C. , Relaño Monica , De Looze Ilse , Baes Maarten , Nersesian Angelos , Camps Peter , Hou Kuan-chou , Oku Yuri
Published: July 2024

Aims. We aim to provide observational signatures of the dust size evolution in the interstellar medium. In particular, we explore indicators of the polycyclic aromatic hydrocarbon (PAH) mass fraction (qPAH), defined as the mass fraction of PAHs relative to the total dust grains. In addition, we validate our dust evolution model by comparing the observational signatures from our simulations to observations.

Methods. We used the hydrodynamic simulation code, GADGET4-OSAKA to model the dust properties of Milky Way-like and NGC 628-like galaxies representing star-forming galaxies. This code incorporates the evolution of grain size distributions driven by dust production and interstellar processing. Furthermore, we performed post-processing dust radiative transfer calculations with SKIRT based on the hydrodynamic simulations to predict the observational properties of the simulations.

Results. We find that the intensity ratio between 8 and 24 μm (Iν(8 μm)/Iν(24 μm)) is correlated with qPAH and can be used as an indicator of the PAH mass fraction. However, this ratio is influenced by the local radiation field. We suggest the 8 μm-to-total infrared intensity ratio (νIν(8 μm)/ITIR) as another indicator of the PAH mass fraction, since it is tightly correlated with the PAH mass fraction. Furthermore, we explored the spatially resolved evolutionary properties of the PAH mass fraction in the simulated Milky Way-like galaxy using νIν(8 μm)/ITIR. We find that the spatially resolved PAH mass fraction increases with metallicity at Z ≲ 0.2 Z⊙ due to the interplay between accretion and shattering, whereas it decreases at Z ≳ 0.2 Z⊙ because of coagulation. Also, coagulation decreases the PAH mass fraction in regions with a high hydrogen surface density. Finally, we compared the above indicators in the NGC 628-like simulation with those observed in NGC 628 by Herschel, Spitzer, and JWST. Consequently, we find that our simulation underestimates the PAH mass fraction throughout the entire galaxy by a factor of ~8 on average. This could be due to the efficient loss of PAHs by coagulation in our model, suggesting that our treatment of PAHs in dense regions needs to be improved.
Modelling non-radially propagating coronal mass ejections and forecasting the time of their arrival at Earth
Authors: Valentino A. , Magdalenic J.
Published: July 2024

We present the study of two solar eruptive events observed on December 7 2020 and October 28 2021. Both events were associated with full halo coronal mass ejections (CMEs) and flares. These events were chosen because they show a strong non-radial direction of propagation in the low corona and their main propagation direction observed in the inner heliosphere is not fully aligned with the Sun-Earth line. This characteristic makes them suitable for our study, which aims to inspect how the non-radial direction of propagation in the low corona affects the time of CMEs’ arrival at Earth. We reconstructed the CMEs using SOHO/LASCO and STEREO/COR observations and modelled them with the 3D MHD model EUHFORIA and the cone model for CMEs. In order to compare the accuracy of forecasting the CME and the CME-driven shock arrival time at Earth obtained from different methods, we also used so-called type II bursts, radio signatures of associated shocks, to find the velocities of the CME-driven shocks and forecast the time of their arrival at Earth. Additionally, we estimated the CME arrival time using the 2D CME velocity obtained from the white light images. Our results show that the lowest accuracy of estimated CME Earth arrival times is found when the 2D CME velocity is used (time difference between observed and modelled arrival time, Δt ≈ −29 h and −39 h, for the two studied events, respectively). The velocity of the type II radio bursts provides somewhat better – but still not very accurate – results (Δt ≈ +21 h and −29 h, for the two studied events, respectively). Employing, as an input to EUHFORIA, the CME parameters obtained from the graduated cylindrical shell (GCS) fittings at consequently increasing heights, results in a strongly improved accuracy of the modelled CME and shock arrival time; Δt changes from 20 h to 10 min in the case of the first event, and from 12 h to 30 min in the case of the second one. This improvement shows that when we increased the heights of the GCS reconstruction we accounted for the change in the propagation direction of the studied CMEs, which allowed us to accurately model the CME flank encounter at Earth. Our results show the great importance of the change in the direction of propagation of the CME in the low corona when modelling CMEs and estimating the time of their arrival at Earth.
Abundances of neutron-capture elements in selected solar-type stars
Authors: Sheminova Valentina , Baratella Martina , D’Orazi Valentina
Published: July 2024

Aims. The primary objective of this study is to accurately determine the abundances of Cu, Sr, Y, Zr, Ba, La, and Ce in selected solar-type stars. This will allow us to establish observational abundance–metallicity and abundance–age relations and to explore the reasons for the excess of Ba compared to other s-elements in younger solar-type stars. The chosen s-process elements are critical diagnostics for understanding the chemical evolution of our Galaxy.

Methods. We analysed HARPS spectra with a high resolution (R = 115 000) and high signal-to-noise ratio (close to 100) of main-sequence solar-type FGK stars with metallicities from −0.15 to +0.35 dex and ages from 2 to 14 Gyr using one-dimensional (1D) local thermodynamic equilibrium (LTE) synthesis and MARCS atmospheric models. In the procedure of fitting synthetic to observed line profiles, the free parameters included abundance and microturbulent and macroturbulent velocity. The macroturbulent velocity can substantially compensate for non-local thermodynamic equilibrium (NLTE) effects in the line core.

Results. The resulting elemental abundance [X/H] increases with metallicity and age for solar-type stars. The ratio of the abundances of s-process elements [s/Fe] increases with decreasing metallicity and age, while the [Cu/Fe] ratio increases with both metallicity and age. These observed trends agree well with published observational data and with predictions from Galactic chemical evolution (GCE) models. A small [Ba/Fe] enhancement of 0.08 ± 0.08 dex has been detected in seven younger stars with an average age of 2.8 ± 0.6 Gyr. Compared to the abundances of other s-process elements, [Ba/Fe] is 0.07 and 0.08 dex higher than La and Ce on average, respectively. Furthermore, we find that the [Ba/Fe] ratio increases with increasing chromospheric activity. The average [Ba/Fe] for the three most active stars is 0.15 ± 0.10 dex higher than that of the other stars. Chromospheric activity, characterised by stronger magnetic fields found in active regions such as pores, spots, plages, and networks, can significantly alter the physical conditions in the formation layers of the Ba lines. Our primary conclusion is that to account for the observed excess of [Ba/Fe] abundance in younger stars, it is essential to use more complex atmospheric models that incorporate magnetic structures.
Impact of the numerical conversion to optical depth on the transfer of polarized radiation
Authors: D’Anna Matteo , Janett Gioele , Belluzzi Luca
Published: July 2024

Context. Making the conversion from the geometrical spatial scale to the optical depth spatial scale is useful in obtaining numerical solutions for the radiative transfer equation. This is because it allows for the use of exponential integrators, while enforcing numerical stability. Such a conversion involves the integration of the total opacity of the medium along the considered ray path. This is usually approximated by applying a piecewise quadrature in each spatial cell of the discretized medium. However, a rigorous analysis of this numerical step is lacking.

Aims. This work is aimed at clearly assessing the performance of different optical depth conversion schemes with respect to the solution of the radiative transfer problem for polarized radiation, out of the local thermodynamic equilibrium.

Methods. We analyzed different optical depth conversion schemes and their combinations with common formal solvers, both in terms of the rate of convergence as a function of the number of spatial points and the accuracy of the emergent Stokes profiles. The analysis was performed in a 1D semi-empirical model of the solar atmosphere, both in the absence and in the presence of a magnetic field. We solved the transfer problem of polarized radiation in different settings: the continuum, the photospheric Sr I line at 4607 Å modeled under the assumption of complete frequency redistribution, and the chromospheric Ca I line at 4227 Å, taking the partial frequency redistribution effects into account during the modeling.

Results. High-order conversion schemes generally outperform low-order methods when a sufficiently high number of spatial grid points is considered. In the synthesis of the emergent Stokes profiles, the convergence rate, as a function of the number of spatial points, is impacted by both the conversion scheme and formal solver. The use of low-order conversion schemes significantly reduces the accuracy of high-order formal solvers.

Conclusions. In practical applications, the use of low-order optical depth conversion schemes introduces large numerical errors in the formal solution. To fully exploit high-order formal solvers and obtain accurate synthetic emergent Stokes profiles, it is necessary to use high-order optical depth conversion schemes.
Strong-lensing and kinematic analysis of CASSOWARY 31: Can strong lensing constrain the masses of multi-plane lenses?
Authors: Wang H. , Cañameras R. , Suyu S. H. , Galan A. , Grillo C. , Caminha G. B. , Christensen L.
Published: July 2024

We present a mass measurement for the secondary lens along the line of sight (LoS) from the multi-plane strong lens modeling of the group-scale lens CASSOWARY 31 (CSWA 31). The secondary lens at redshift z = 1.49 is a spiral galaxy well aligned along the LoS with the main lens at z = 0.683. Using the MUSE integral-field spectroscopy of this spiral galaxy, we measured its rotation velocities and determined the mass from the gas kinematics. We compared the mass estimation of the secondary lens from the lensing models to the mass measurement from kinematics, finding that the predictions from strong lensing tend to be higher. By introducing an additional lens plane at z = 1.36 for an overdensity known to be present, we find a mass of ≃1010 M⊙ enclosed within 3.3 kpc of the centroid of the spiral galaxy, which approaches the estimate from kinematics. This shows that secondary-lens mass measurements from multiple-plane modeling are affected by systematic uncertainties from the degeneracies between lens planes and the complex LoS structure. Conducting a detailed analysis of the LoS structures is therefore essential to improve the mass measurement of the secondary lens.
Carbon enrichment in APOGEE disk stars as evidence of mass transfer in binaries
Authors: Foster Steve , Schiavon Ricardo P. , de Castro Denise B. , Lucatello Sara , Daher Christine , Penoyre Zephyr , Price-Whelan Adrian , Badenes Carles , Fernández-Trincado José G. , García-Hernández Domingo Aníbal , Holtzman Jon , Jönsson Henrik , Shetrone Matthew
Published: July 2024

Context. Carbon abundances in first-ascent giant stars are usually lower than those of their main-sequence counterparts. At moderate metallicities, stellar evolution of single stars cannot account for the existence of red-giant branch stars with enhanced carbon abundances. The phenomenon is usually interpreted as resulting from past mass transfer from an evolved binary companion now in the white dwarf evolutionary stage.

Aims. We aim to confirm the links between [C/O] enhancement, s-process element enhancement and binary fraction using large-scale catalogues of stellar abundances and probable binary stars.

Methods. We use a large data set from the 17th data release of the SDSS-IV/APOGEE 2 survey to identify carbon-enhanced stars in the Galactic disk. We identify a continuum of carbon enrichment throughout three different sub-populations of disk stars and explore links between the degree of carbon enrichment and binary frequency, metallicity and chemical compositions.

Results. We verify a clear correlation between binary frequency and enhancement in the abundances of both carbon and cerium, lending support to the scenario whereby carbon-enhanced stars are the result of mass transfer by an evolved binary companion. In addition, we identify clustering in the carbon abundances of high-α disk stars, suggesting that those on the high metallicity end are likely younger, in agreement with theoretical predictions for the presence of a starburst population following the gas-rich merger of the Gaia-Enceladus/Sausage system.
Five new eclipsing binaries with low-mass companions
Authors: Lipták J. , Skarka M. , Guenther E. , Chaturvedi P. , Vítková M. , Karjalainen R. , Šubjak J. , Hatzes A. , Bieryla A. , Gandolfi D. , Albrecht S. H. , Beck P. G. , Deeg H. J. , Everett M. E. , Higuera J. , Jones D. , Mathur S. , Patel Y. G. , Persson C. M. , Redfield S. , Kabáth P.
Published: July 2024

Precise space-based photometry from the Transiting Exoplanet Survey Satellite results in a huge number of exoplanetary candidates. However, the masses of these objects are unknown and must be determined by ground-based spectroscopic follow-up observations, frequently revealing the companions to be low-mass stars rather than exoplanets. We present the first orbital and stellar parameter solutions for five such eclipsing binary-star systems using radial-velocity follow-up measurements together with spectral-energy-distribution solutions. TOI-416 and TOI-1143 are totally eclipsing F+M star systems with well-determined secondary masses, radii, and temperatures. TOI-416 is a circular system with an F6 primary and a secondary with a mass of M2 = 0.131(8) M⊙. TOI-1143 consists of an F6 primary with an M2 = 0.142(3) M⊙ secondary on an eccentric orbit with a third companion. With respect to the other systems, TOI-1153 shows ellipsoidal variations, TOI-1615 contains a pulsating primary, and TOI-1788 has a spotted primary, while all have moderate mass ratios of 0.2–0.4. However, these systems are in a grazing configuration, which limits their full description. The parameters of TOI-416B and TOI-1143B are suitable for the calibration of the radius-mass relation for dwarf stars.