bluuebunny/crossref_metadata_2025 huggingface dataset:
Silver-catalyzed regioselective synthesis of pyrano heterocycles: a versatile route to samoquasine A derivatives
Authors: Chahal Kapil , Badhavath Ravikumar , Matharu Simran Kaur , Vinod Anjana , Vani Damera , Potluri Vijaya Rani , Sridhar Balasubramanian , Reddy Kallu Rajender
Published: October 2024

A silver-catalyzed method for pyrano heterocycles synthesis was developed, with the products efficiently transformed into samoquasine A derivatives, demonstrating potential in natural product synthesis and drug discovery.
Preparation of organic compound/g-C3N4 composites and their applications in photocatalysis
Authors: Wu Jun , Ding Xingchen , Zhu Xiashi
Published: October 2024

This review mainly summarises the progress in the preparation methods of organic compound/g-C3N4. Various materials such as different types of organic compound/g-C3N4 composites and their related energy and environmental applications are discussed.
Diversity-oriented chiral phosphoric acid catalyzed alkylation of indolizines with aminals
Authors: Kassir Ahmad F. , Rad Nazar , Klochowicz Patryk , Granda Jarosław M.
Published: October 2024

This study introduces enantioselective indolizine alkylation with aminals via chiral phosphoric acid catalysis, featuring scalable, functional group-tolerant processes, enabling access to diverse C1/C3-alkylated indolizines.
Reaction contest: hydrolysis versus intramolecular cyclisation reaction in alkyl squaramate esters
Authors: Ximenis Marta , Cañellas Santiago , Gomila Rosa M. , Galmés Bartomeu , Frontera Antonio , Costa Antonio , Rotger Carmen
Published: October 2024

The hydrolytic behavior and stability of squaramate esters have been investigated, shedding light on the competition between hydrolysis and intramolecular cyclization reactions, which is crucial for advancing bioconjugate chemistry applications.
A facile, catalyst- and additive-free, and scalable approach to the photochemical preparation of disulfides from organosulfenyl chlorides
Authors: Liu Wei , Wang Jiayi , Song Gonghua
Published: October 2024

Various disulfides were prepared by the homo- and cross-coupling of sulfenyl chlorides under LED irradiation without the use of any catalyst or additive. The representative reaction was performed on kilogram-scale in a continuous flow mode.
Constructed wetlands combined with microbial fuel cells (CW-MFCs) as a sustainable technology for leachate treatment and power generation
Authors: Arliyani Isni , Noori Md Tabish , Ammarullah Muhammad Imam , Tangahu Bieby Voijant , Mangkoedihardjo Sarwoko , Min Booki
Published: October 2024

The physical and chemical treatment processes of leachate are not only costly but can also produce harmful by-products.
A curcumin quantum dot blended polyacrylonitrile electrospun nanofiber coating on 316 L SS for improved corrosion resistance in the marine environment
Authors: Badsha Iffath , Rasal Renjith Kumar , Taweepreda Wirach , Gangasalam Arthanareeswaran , Thiyagarajan Devasena
Published: October 2024

PAN-CMQD nanofiber coating on 316 L SS for improved corrosion resistance in marine environment.
Supramolecular motifs formed by CH3/Cl-substituted arene groups: evidence for structural differences in thiophosphoramides and similarities in their complexes
Authors: Hosseinpoor Saeed , Pourayoubi Mehrdad , Zmeškalová Eliška , Poupon Morgane
Published: October 2024

Different electrostatic potentials of the Cl/CH3 substituted aryl groups affect the molecular packings of thiophosphoramides/complexes in distinct ways.
Molecular design and functional outcomes of RTP and TADF traits in isomers
Authors: Chen Meiling , Chen Yuzhuo , Zhang Ting , Zhang Hua , Xiao Zhiwen , Su Zhongzhen , Wu Yunan
Published: October 2024

Three isomers (3Fmo, 3Fmm, 3Fmp) were synthesized with distinct luminescent properties. 3Fmm showed room-temperature phosphorescence due to unique π–π stacking, while 3Fmo and 3Fmp exhibited TADF. 3Fmo excelled in cellular imaging.
Piezoelectric GaGeX2 (X = N, P, and As) semiconductors with Raman activity and high carrier mobility for multifunctional applications: a first-principles simulation
Authors: Vu Tuan V. , Hiep Nguyen T. , Hoa Vo T. , Nguyen Chuong V. , Phuc Huynh V. , Hoi Bui D. , Kartamyshev A. I. , Hieu Nguyen N.
Published: October 2024

In the present work, we propose GaGeX2 (X = N, P, As) monolayers and explore their structural, vibrational, piezoelectric, electronic, and transport characteristics for multifunctional applications based on first-principles simulations.
Chemical synthesis and application of aryldihydronaphthalene derivatives
Authors: Chen Xia , He Zhaolong , Xu Shiqiang , Zou Yu , Zhang Yonghui
Published: October 2024

This review summarizes the synthetic protocols and application of aryldihydronaphthalenes (ADHNs) since 2000.
Exploring the potential of natural orbital functionals
Authors: Piris Mario
Published: October 2024

In recent years, Natural Orbital Functional (NOF) theory has gained importance in quantum chemistry, effectively addressing a major challenge: providing accurate and balanced descriptions of systems with strong electronic correlation.
A review on Ti3C2Tx based nanocomposites for the electrochemical sensing of clinically relevant biomarkers
Authors: Sugunan Anjali , Rethnakumaran Anusree V. , Menamparambath Mini Mol
Published: October 2024

Classification of various Ti3C2Tx MXene-based nanocomposites, highlighting the structural–property correlation and impact of MXene on electrochemical performance of nanocomposites.
A pdc-pinched copper complex for sustainable hydrogen production through ligand supported-metal centric proton-coupled electron transfer
Authors: Chettri Meena , Saha Subhajit , Diyali Nilankar , Debnath Rakesh , Bagdwal Harshita , Singh Monika , Biswas Bhaskar
Published: October 2024

This manuscript deals with the electrocatalytic fate of a water-stable pdc-pinched copper complex for sustainable hydrogen production.
Shaping the future of methanol production through carbon dioxide utilisation strategies
Authors: Fernández-González Javier , Rumayor Marta , Laso Jara , Domínguez-Ramos Antonio , Irabien Angel
Published: October 2024

Decarbonising chemical vectors used for transportation is a top priority for Europe to become carbon-neutral by 2050.
Tuning collective actuation of active solids by optimizing activity localization
Authors: Lazzari Davi , Dauchot Olivier , Brito Carolina
Published: October 2024

Active solids, more specifically elastic lattices embedded with polar active units, exhibit collective actuation when the elasto-active feedback, generically present in such systems, exceeds some critical value.
Microphase-separation-induced polyzwitterionic ionogel with tough, highly conductive, self-healing and shape–memory properties for wearable electrical devices
Authors: Zeng Guang , Gao Wenshuo , Qiu Weicheng , Li Guanling , Chen Shousen , He Xin , Sun Guoxing , Yang Weijia , Xin Yue
Published: October 2024

A polyzwitterionic ionogel with a phase separation structure was designed to achieve a balance between mechanical robustness and ionic conductivity. This design holds immense potential for applications in wearable sensors.
CrysGraphFormer: an equivariant graph transformer for prediction of lattice thermal conductivity with interpretability
Authors: Sun Zhengyu , Sun Weiwei , Li Shaohan , Yang Zening , Zhang Mutian , Yang Yang , Geng Huayun , Yu Jin
Published: October 2024

We propose an innovative GNN model, CrysGraphFormer, which accurately predicts lattice thermal conductivity and enhances insights for material discovery.
An azo-receptor immobilized mesoporous honeycomb silica framework as a solid-state chromogenic sensor for capturing ultra-trace cadmium ions from environmental/industrial samples
Authors: Veedu Anju P. , Jeyakumar Balasurendran , Mohan Akhila Maheswari , Kuppusamy Satheesh , Chinaraga Pitchaiah K. , Muthurathinam Manjula , Rao C. V. S. Brahmananda , Nagarajan Sivaraman , Deivasigamani Prabhakaran
Published: October 2024

A solid-state naked-eye sensor composed of a mesoporous honeycomb structured silica monolith impregnated with a DMTHBD receptor offers a simple, rapid and eco-benign approach for the selective sensing of trace Cd2+, with brilliant color transitions.
Lewis acid sites and flexible active centers synergistically boost efficient electrochemical ammonia synthesis
Authors: Chen Li-Bo , Wang Tong-Hui , Lang Xing-You , Jiang Qing
Published: October 2024

The Lewis acid sites enhance N2 adsorption and activation, while the flexible active center facilitates hydrogenation and NH4+ formation, regenerating the catalyst.
A black zirconia cathode coating layer enabling facile charge diffusion and surface lattice stabilization for lithium-ion batteries
Authors: Choi Yoo Jung , Jang Sungbin , Chang Hongjun , Kim Youjin , Kim Suji , Kim Ga Yoon , Lee Juho , Moon Janghyuk , Kim Jinsoo , Ryu Won-Hee
Published: October 2024

Black ZrO2−x is coated onto a Ni-rich cathode via solvent-free shearing, enhancing charge transfer, reducing gas evolution, and preventing cracking. It lowers Li-ion transfer barriers and mitigates oxygen release through strong Zr–O hybridization.
Multifunctional additive enables lead-adsorbing carbon electrodes for perovskite solar cells
Authors: Jiang Yuanzhu , Zhu Aodong , Liao Teng , Zhao Wang , Cheng Mengmeng , Zhang Xinxin , Cheng Yi-Bing , Xiao Junyan
Published: October 2024

Phosphate, being a single-component multifunctional additive, serves as a viable material for the carbon electrode in perovskite solar cells. This utilization ensures the device's performance and mitigates the risk of potential lead pollution.
Recent review on self-supported one-dimensional core/shell nanostructures based on WO3 for enhanced electrochromism
Authors: Su Jiangbin , Chen Longlong , Xu Chunyan , Liu Yu , Shen Long , He Zuming
Published: October 2024

This review analyzes the advantages of self-supported one-dimensional core/shell nanostructures (SS1DCSNs) for electrochromic applications and provides an in-depth examination of current literature on WO3-based SS1DCSNs.
Delineating the intricacies of niobium-modified high-nickel layered cathodes with a single-step synthesis
Authors: Watts Thomas J. , Manthiram Arumugam
Published: October 2024

Single-step syntheses of Nb-modified layered oxides suffer from higher Li+/Ni2+ mixing and ferroelectric Li3NbO4 phase formation. High-voltage cycling offsets overpotential, facilitating HF scavenging, conversion to LiNbO3, and improved cyclability.
Two-dimensional alkaline-earth metal monohalides in unusually low oxidation states with high performance for ion batteries and electrochemical water splitting
Authors: Liu Linlin , Jiang Bowen , Sun Dan , Liu Hanyu , Xie Congwei , Butler Keith , Xie Yu
Published: October 2024

Exploring the low oxidation states of alkaline earth metal elements with natural abundance can be useful for renewable energy applications and is highly desirable.
Exploring reaction mechanisms for CO2 reduction on carbides
Authors: Ashraf Naveed , Iqbal Atef , Abghoui Younes
Published: October 2024

The electrocatalytic conversion of carbon dioxide (CO2) into valuable fuels offers immense promise in pursuing sustainable energy solutions.
Down-converting ultraviolet light using a conductive passivator to enhance the efficiency and stability of perovskite solar cells
Authors: Yu Honglei , He Zhengyan , Liu Xiangheng , Zhang Zhiqiang , Li Yongjia , Zhang Shufang , Zhang Qi , Yao Changlin , Zhong Hai
Published: October 2024

DSDA simultaneously down-converts ultraviolet light and enhances the conductivity of SnO2; DSDA effectively passivates defects at the SnO2/perovskite interface while providing in situ protection against lead leakage.
Dissolving microneedles: standing out in melanoma treatment
Authors: Huang Jingting , Wang Xihao , Li Zhengyong
Published: October 2024

Melanoma is one of the most significant and dangerous superficial skin tumors with a high fatality rate, thanks to its high invasion rate, drug resistance and frequent metastasis properties.
A bioinspired porous and electroactive reduced graphene oxide hydrogel based biosensing platform for efficient detection of tumor necrosis factor-α
Authors: Kapil Parth , Verma Damini , Pradhan Rangadhar , Kalkal Ashish , Packirisamy Gopinath
Published: October 2024

Synthesis of an l-cys_rGO hydrogel and fabrication of a BSA/anti-TNF-α/l-cys_rGO hydrogel/gSPE immunosensor.
Enzyme/pH-sensitive nanoparticles based on poly(β-l-malic acid) for drug delivery with enhanced endocytosis
Authors: Guo Songyan , Qiao Youbei , Wang Chaoli , Zhang Yuming , Yang Tiehong , Wu Hong
Published: October 2024

We report a nanoparticle system based on PMLA to enhance drug delivery, improve cellular uptake, and achieve controlled intracellular drug release owing to enzyme-sensitive linker named AANL and pH-sensitive bond named cis-aconitic anhydride bond.
Selective etching of ITO–PET using a dry film photoresist for large area metamaterial fabrication
Authors: Bhattacharya Sudeb , Chaudhary Kajal , Aakash  , Ramkumar J. , Srivastava Kumar Vaibhav
Published: October 2024

An industrially scalable wet etching technique to pattern ITO from PET substrates using dry film photoresist was developed. This process preserves the substrate’s integrity, maintaining electrical and optical properties.
Ultrathin and flexible PDA modified MXene/bacterial cellulose composite film with a dense lamellar structure for enhanced electromagnetic interference shielding performance
Authors: Wen Cuilian , Liu Hao , Luo Lijin , Cui Zhou , Li Xiong , Jin Junhao , Yan Siqing , Lin Peng , Sa Baisheng
Published: October 2024

Ultrathin and flexible PM/BC films with dense lamellar structures have been developed by experimental and theoretical investigations, exhibiting superior EMI shielding performance, which show great potential for the protection of electronic devices.
Towards deep NIR emissive simple D–A–D dyes: a novel acceptor block providing anti-Kasha's rule emission
Authors: Korshunov Vladislav M. , Chmovzh Timofey N. , Tsorieva Alisia V. , Gruzdev Gleb A. , Rakhimkulov Dadozhon M. , Taydakov Ilya V. , Rakitin Oleg A.
Published: October 2024

Novel fluorescent 1,2,5-selenadiazolo[3,4-d]pyridazines demonstrate intensive emission in the NIR spectral region of 900–1100 nm; introduction of the selenium leads to the Kasha rule violation followed by a red-shift of the emission spectra.
Enhanced capacitive energy storage of NaNbO3-based relaxor via modulating the phase structure strategy for high power energy storage
Authors: Huang Jiangping , Xu Mingzhao , Pan Yue , Huang Yanchun , Zhou Huanfu , Li Xu , Chen Xiuli
Published: October 2024

A schematic diagram of the design strategy to achieve high energy storage performance via the phase structure strategy: (a) and (b) dielectric temperature spectra, (c) PFM phase images, and (d) slim unipolar P–E hysteresis loop.
Optimization of TbAl grain boundary diffusion sources for sintered Nd–Fe–B magnets by low cost Nd substitution for Tb
Authors: Nguyen Thi Mai , Kou Mingpeng , He Jiayi , Chen Shiying , Zhang Xuhang , Zeng Chaochao , Wei Zuchun , Yu Hongya , Liu Zhongwu
Published: October 2024

A low-cost Nd–Tb–Al alloy diffusion source was developed to improve the diffusion efficiency of Tb by introducing Nd for diffusion channel construction in this work.
Single microbe photoelectrochemical device using scanning electrochemical microscopy
Authors: Samuel Arun Kumar , Shinde Shweta , Palaniappan Alagammai , Bhalla Prerna , Chandiran Aravind Kumar
Published: October 2024

Single microbial bio-photoelectrochemical device is made using scanning electrochemical microscopy with Synechocystis Pevalekii and its performance is compared with bulk devices. Metabolic modeling reveals reactions behind photocurrent generation.
A facilely fabricated electrochemical self-powered pressure sensor for multifunctional applications
Authors: Huang Zekai , Duan Zaihua , Huang Qi , Yuan Zhen , Jiang Yadong , Tai Huiling
Published: October 2024

A facilely fabricated, low-cost and multifunctional electrochemical self-powered pressure sensor is achieved using a simple method and cheap raw materials.
Pillararene-based rare-earth luminescent probe for two-channel simultaneous detection of ROS and ATP in living cells
Authors: Bao Shanshan , Guo Yanan , Lv Dandan , Wang Congcong , Kou Yao , Yang Yuchen , Song Nan , Tang Yu
Published: October 2024

A supramolecular fluorescent probe based on unique fluorescence of Eu-complex and precise recognition of pillar[5]arene is developed for two channel simultaneous detection of H2O2 and ATP in living cells.
Sharing Stories Versus Explaining Facts: Comparing African American Children's Microstructure Performance Across Fictional Narrative, Informational, and Procedural Discourse
Authors: Gardner-Neblett Nicole , Alvarez Dulce Lopez
Published: October 2024

Purpose:

Both fictional oral narrative and expository oral discourse skills are critical language competencies that support children's academic success. Few studies, however, have examined African American children's microstructure performance across these genres. To address this gap in the literature, the study compared African American children's microstructure productivity and complexity across three discourse contexts: fictional narratives, informational discourse, and procedural discourse. The study also examined whether there were age-related differences in microstructure performance by discourse type.

Method:

Participants were 130 typically developing African American children, aged 59–95 months old, enrolled in kindergarten through second grades in a Midwestern U.S. public school district. Wordless children's books were used to elicit fictional narratives, informational, and procedural discourse. Indicators of microstructure performance included measures of productivity (i.e., number of total words and number of different words) and complexity (i.e., mean length of communication unit and complex syntax rate). The effects of genre and age on microstructure performance were assessed using linear mixed-effects regression models.

Results:

Children produced longer discourse and used a greater diversity of words for their fictional stories compared to their informational or procedural discourse. Grammatical complexity was greater for fictional narratives and procedural discourse than informational discourse. Results showed greater productivity and complexity among older children compared to younger children, particularly for fictional and informational discourse.

Conclusions:

African American children exhibit variation in their microstructure performance by discourse context and age. Understanding this variation is key to providing African American children with support to maximize their oral language competencies.
E‐Commerce Logistics Software Package Tracking and Route Planning and Optimization System of Embedded Technology Based on the Intelligent Era
Authors: Zhang Dan , Jia Zhiyang
Published: October 2024

In the Internet era, the e‐commerce industry has risen, its development scale continues to expand, cross‐border e‐commerce (CBEC) has also been born, and it is now in the stage of sustainable development. The rapid development of CBEC also needs the strong support of logistics, the two are inseparable, and today, the development scale of CBEC is constantly expanding. The existing e‐commerce logistics (ECL) model is also gradually unable to meet the increasingly diverse needs of users, and new logistics models need to be actively explored. To change this situation, this paper carried out a specific analysis of CBEC logistics model, and applied embedded technology to ECL, which also built a logistics tracking system. At the same time, combined with the ant colony algorithm, the paper carried out experimental research on the logistics package distribution route planning problem. From the experimental results, in terms of average delivery time, the algorithm’s result was 25.95 hr, while the traditional algorithm was 32.53 hr; in terms of average distribution freight cost, the algorithm’s result was 163.3 yuan, while the traditional algorithm was 257.7 yuan; in terms of average distribution cost, this algorithm’s result was 131.53 yuan, while the traditional algorithm was 211.68 yuan. To sum up, this algorithm could effectively optimize the distribution route of logistics packages and improve the efficiency of package transportation.
Dynamic overmodulation strategy based on torque and flux optimal tracking for DTC‐SVM of surface‐mounted PMSM drives
Authors: Li Peihe , Shen Anwen , Tang Qipeng , Luo Xin , Xu Jinbang
Published: October 2024

Direct torque control with space vector modulation has been increasingly attracting emphasis for permanent‐magnet synchronous machine control, benefiting from a high dynamic response and low torque ripple. However, the rapid tracking performance of torque and stator flux linkage is gradually deteriorating as the machine enters the overmodulation region because of the output‐voltage limitation of the inverter. Therefore, to enhance the system tracking performance in the overmodulation region, an innovative overmodulation method based on torque and flux optimal tracking is proposed. In contrast to the conventional overmodulation method where only one of the torque and stator flux linkage tracking is considered, the proposed strategy first constructs the weightless cost function to achieve a trade‐off control between the torque and stator flux linkage. Then, by using an equivalent geometric path to intuitively express the weightless cost function, the minimum cost function can be easily solved and the optimal output voltage vector can be determined correspondingly, to achieve the fast‐tracking of both the torque and stator flux linkage. Additionally, the voltage utilization of different overmodulation schemes is also analysed. Finally, the experimental results demonstrate the efficiency and practicality of the proposed strategy.
Double power MOSFETs high‐gain DC–DC topology using two‐winding coupled inductor for renewable energy usage
Authors: Abbasian Sohrab , Zakerian Ali , Farsijani Mohammad , Nikbakht Masoud , Roinila Tomi
Published: October 2024

High‐voltage DC–DC converters are critical components of numerous renewable‐energy systems. Input current and voltage gain are crucial factors to consider while designing these converters. This article suggests a high‐step‐up DC–DC topology. Utilizing a magnetic‐coupling‐based voltage multiplier approach, the suggested converter achieves significant voltage gain while minimizing switch voltage stress. Furthermore, a boost inductor at the input ensures continuous input current, making it useful for battery, fuel cell, and solar energy systems. In addition, the MOSFETs are switched at zero voltage, yielding low switching losses, and the coupled inductor is biased toward zero DC, which results in a small magnetic area and lower core losses. The proposed converter's operating regulations, performance studies, and design challenges are discussed. To confirm the calculations made in theory, a test was performed with a 20 V input and a 230 V output, providing an output power of 425 W.
DeepEMS: Multimodal optimal energy management of microgrid systems based on a hybrid multi‐stage machine learning model
Authors: Safari Ashkan , Hashemzadeh Farzad , Zare Kazem
Published: October 2024

The effective management of microgrids is important towards transition to sustainable energy paradigm. By optimizing the utilization of different energy sources, such as solar photovoltaic panels and energy storages, it improves the reliability of the grid and develops resiliency in dealing with of challenges of unexpected variations in demand. To this end, the proposed paper presents DeepEMS, a system developed to manage the energy of microgrids through the incorporation of diverse intelligent algorithms. DeepEMS provides dynamic microgrid management through the utilization of Bidirectional Long Short‐Term Memory (BiLSTM) networks, Sliding Linear Programming (SLP), and Random Forest (RF). By implementing these methodologies, DeepEMS can optimize energy consumption throughout the microgrid by dynamically identifying and coordinating the needs of various energy sources. DeepEMS achieves precise multimodal optimization and facilitates integration of storage systems, grid interactions, and renewable energy sources (RES), as demonstrated by simulations and data analytics. DeepEMS presented performance in control, resource allocation, management, and grid utilization. Furthermore, in a comparative analysis with alternative intelligent models including XGBoost, Light GBM, RF, and Decision Trees, DeepEMS consistently demonstrated higher performance as measured by several key performance indicators (KPIs).
Ethanolamine ices: Experiments in simulated space conditions
Authors: Biancalani Sole , Corazzi Maria A. , Rivilla Víctor M. , Brucato John R.
Published: October 2024

Context. Laboratory experiments on the interactions between complex organic molecules, interstellar dust, and ultraviolet (UV) radiation are crucial to understanding the physicochemical mechanisms that lead to the synthesis of the observed interstellar complex organic molecules (iCOMs), and to search for new molecular species not yet observed in the gas phase of the interstellar medium (ISM).

Aims. We aim to study the role of a new, recently discovered interstellar molecule, ethanolamine (EtA, NH2CH2CH2OH), in surface chemistry in the ISM.

Methods. In the laboratory, thanks to a combination of temperature programmed desorption (TPD) experiments and electron ionization (EI) mass spectrometry analyses, we studied the thermal desorption of pure ethanolamine and its mixture with water from nanometric amorphous olivine grains cooled down to 10 K, with or without UV irradiation.

Results. Ethanolamine was found to be stable, even in the presence of water, when irradiated with UV light. The presence of olivine grains strongly modified the TPD curves, trapping the molecule up to about 295 K, meaning that the precursors of some biological molecules could be retained on the grains even in the innermost parts of protoplanetary disk. We then identified a series of products formed when the molecule was irradiated onto the dust substrate.

Conclusions. Of particular interest is the fact that irradiation of ice containing ethanolamine, a molecule known to be present in the ISM, can produce more complex and astrobiologically interesting species. Furthermore, our results further our understanding of existing observational data.
The stellar population of a z ∼ 3.25 Lyα-emitting group associated with a damped Lyα absorber
Authors: Pruto Giulia , Fumagalli Michele , Rafelski Marc , Revalski Mitchell , Fossati Matteo , Mackenzie Ruari , Theuns Tom
Published: October 2024

We present near-infrared observations, acquired with the Wide Field Camera 3 (WFC3) on board the Hubble Space Telescope (HST), of a Lyα-emitting double-clumped nebula at z ≈ 3.25 associated with a damped Lyα absorber (DLA). With the WFC3/F160W data we observe the stellar continuum around 3600 Å in the rest frame of a galaxy embedded in the west clump of the nebula, GW, for which we estimate a star formation rate (SFR) of SFRGW = 5.0 ± 0.4 M⊙ yr−1 and a maximum stellar mass MGW < 9.9 ± 0.7 × 109 M⊙. With the enhanced spatial resolution of HST, we discover the presence of an additional faint source, GE, in the center of the east clump, with SFRGE = 0.70 ± 0.20 M⊙ yr−1 and a maximum stellar mass MGE < 1.4 ± 0.4 × 109 M⊙. We show that the Lyα emission in the two clumps can be explained by recombination following in situ photoionization by the two galaxies, assuming escape fractions of ionizing photons of ≲0.24 for GW and ≲0.34 for GE. The fact that GW is offset by ≈8 kpc from the west clump means we cannot fully rule out the presence of additional fainter star-forming sources, which would further contribute to the photon budget inside this ≈1012 M⊙ galaxy group that extends over a region of 30 × 50 kpc.
Magnetic connectivity from the Sun to the Earth with MHD models
Authors: Kennis S. , Perri B. , Poedts S.
Published: October 2024

Context. The magnetic connectivity between the Sun and the Earth is crucial to our understanding of the solar wind and space weather events. However, establishing this connectivity is challenging because of the lack of direct observations, which explains the need for reliable simulations.

Aims. The method most often used to make such measurements over the last few years is the two-step ballistic method, but it has many free parameters that can affect the final result. Thus, we want to provide a connectivity method based on self-consistent magnetohydrodynamics (MHD) models.

Methods. To this end, we combined the COCONUT coronal model with the EUHFORIA heliospheric model to compute the magnetic field lines from the Earth to the Sun. We then developed a way to quantify both the spatial and temporal uncertainty associated with this computation. To validate our method, we selected four cases already studied in the literature and associated with high-speed-stream events coming from unambiguous coronal holes visible on the disk.

Results. We always find a partial overlap with the assumed CH of origin. The extent of this overlap is 19% for event 1, 100% for event 2, 45% for event 3, and 100% for event 4. We looked at the polarity at Earth over the full Carrington rotation to better understand these results. We find that, on average, MHD simulations provide a very good polarity estimation, showing 69% agreement with real data for event 1, 36% for event 2, 68% for event 3, and 69% for event 4. For events 1 and 3, we can then explain the mixed results by the spatial and temporal uncertainty. An interesting result is that, for MHD models, minimum-activity cases appear to be more challenging because of the multiple recurrent crossings of the HCS, while maximum-activity cases appear easier because of the latitudinal extent of the HCS. A similar result was also found with Parker Solar Probe data in another study.

Conclusions. We demonstrate that it is possible to use MHD models to compute magnetic connectivity and that this approach provides results of equal quality to those from the two-step ballistic method, with additional possibilities for improvements as the models integrate more critical physics.
Evolution of lithium in the disc of the Galaxy and the role of novae
Authors: Borisov Sviatoslav , Prantzos Nikos , Charbonnel Corinne
Published: October 2024

Context. Lithium plays a crucial role in probing stellar physics, stellar and primordial nucleosynthesis, and the chemical evolution of the Galaxy. Stars are considered to be the main source of Li, yet the identity of its primary stellar producer has long been a matter of debate.

Aims. In light of recent theoretical and observational results, we investigate in this study the role of two candidate sources of Li enrichment in the Milky Way, namely asymptotic giant branch (AGB) stars and, in particular, novae.

Methods. We utilised a one-zone Galactic chemical evolution (GCE) model to assess the viability of AGB stars and novae as stellar sources of Li. We used recent theoretical Li yields for AGB stars, while for novae we adopted observationally inferred Li yields and recently derived delay time distributions (DTDs). Subsequently, we extended our analysis by using a multi-zone model with radial migration to investigate spatial variations in the evolution of Li across the Milky Way disc and compared the results with observational data for field stars and open clusters.

Results. Our analysis shows that AGB stars clearly fail to reproduce the meteoritic Li abundance. In contrast, novae appear as promising candidates within the adopted framework, allowing us to quantify the contribution of each Li source at the Sun’s formation and today. Our multi-zone model reveals the role of the differences in the DTDs of Type Ia supernovae and novae in shaping the evolution of Li in the various galactic zones. Its results are in fair agreement with the observational data for most open clusters, but small discrepancies appear in the outer disc.
Origin of transition disk cavities
Authors: Huang Shuo , van der Marel Nienke , Portegies Zwart Simon
Published: October 2024

Context. Protoplanetary disks surrounding young stars are the birth places of planets. Among them, transition disks with inner dust cavities of tens of au are sometimes suggested to host massive companions. Yet, such companions are often not detected.

Aims. Some transition disks exhibit a large amount of gas inside the dust cavity and relatively high stellar accretion rates, which contradicts typical models of gas-giant-hosting systems. Therefore, we investigate whether a sequence of low-mass planets can create the appearance of cavities in the dust disk.

Methods. We evolve the disks with low-mass growing embryos in combination with 1D dust transport and 3D pebble accretion, to investigate the reduction of the pebble flux at the embryos’ orbits. We vary the planet and disk properties to understand the resulting dust profile.

Results. We find that multiple pebble-accreting planets can efficiently decrease the dust surface density, resulting in dust cavities consistent with transition disks. The number of low-mass planets necessary to sweep up all pebbles decreases with decreasing turbulent strength and is preferred when the dust Stokes number is 10−2 − 10−4. Compared to dust rings caused by pressure bumps, those by efficient pebble accretion exhibit more extended outer edges. We also highlight the observational reflections: the transition disks with rings featuring extended outer edges tend to have a large gas content in the dust cavities and rather high stellar accretion rates.

Conclusions. We propose that planet-hosting transition disks consist of two groups. In Group A disks, planets have evolved into gas giants, opening deep gaps in the gas disk. Pebbles concentrate in pressure maxima, forming dust rings. In Group B, multiple Neptunes (unable to open deep gas gaps) accrete incoming pebbles, causing the appearance of inner dust cavities and distinct ring-like structures near planet orbits. The morphological discrepancy of these rings may aid in distinguishing between the two groups using high-resolution ALMA observations.
The currently observed clumps cannot be the “direct” precursors of the currently observed open clusters
Authors: Zhou Jian-wen , Dib Sami , Kroupa Pavel
Published: October 2024

We categorized clumps, embedded clusters, and open clusters and conducted a comparative analysis of their physical properties. Overall, the radii of open clusters are significantly larger than those of embedded clusters and clumps. The radii of embedded clusters are larger than those of clumps, which may be due to the expansion of embedded clusters. The open clusters have significantly higher masses than embedded clusters, by about one order of magnitude. Given the current mass distribution of clumps in the Milky Way, the evolutionary sequence from a single clump evolving into an embedded cluster and subsequently into an open cluster cannot account for the observed open clusters with old ages and high masses, which is also supported by N-body simulations of individual embedded clusters. To explain the mass and radius distributions of the observed open clusters, initial embedded clusters with masses higher than 3000 M⊙ are necessary. However, the upper limit of the embedded cluster sample is less than 1000 M⊙, and only a few ATLASGAL clumps have a mass higher than 3000 M⊙. Thus, the currently observed clumps cannot be the “direct” precursors of the currently observed open clusters. If the Milky Way has a burst-like and time-dependent star formation history, the currently observed open clusters with old ages and high masses may come from massive clumps in the past. There is also a very real possibility that these open clusters originate from post-gas expulsion coalescence of multiple embedded clusters. We compared the separation of open clusters and the typical size of molecular clouds, and find that most molecular clouds may only form one open cluster, which supports the scenario of post-gas expulsion coalescence. Further study is necessary to distinguish between the different scenarios.
No Maunder Minimum phase in HD 4915
Authors: Flores Trivigno M. , Buccino A. P. , González E. , Colombo P. D. , González C. , Jaque Arancibia M. , Ibañez Bustos R. V. , Saffe C. , Miquelarena P. , Alacoria J. , Collado A.
Published: October 2024

Context. The long-term solar magnetic activity and its cyclical behaviour, which is maintained by a dynamo mechanism, are both still challenging problems for astrophysics. In particular, an atypical event occurred between 1645 and 1715, when the solar activity was remarkably decreased and the number of sunspots was extremely reduced. However, the exact events that unfolded during the solar cycle remain unclear. The discovery of longer activity minima in cool stars may shed light on the nature of the complex mechanisms involved in the long-term behaviour of the solar-stellar dynamo.

Aims. Our aim is to explore whether the G5V solar-like star HD 4915, which showed a striking chromospheric activity pattern in a previous study performed with HIRES data, might be considered a bona fide Maunder Minimum (MM) candidate.

Methods. We analysed over 380 spectra acquired between 2003 and 2022 using the HARPS and HIRES spectrographs. We carried out a detailed search for activity signatures in HD 4915 by using the Mount Wilson and the Balmer Hα activity indexes. This task was performed by means of the generalised Lomb-Scargle periodogram.

Results. The new HARPS data show that the chromospheric activity of HD 4915 is not decreasing. In fact, the increases in the activity after the broad minimum in three years reaches the level of activity before this phase, suggesting that it is not entering an MM phase. We also calculate a rotation period of 23.4 ± 0.2 d, which has not been reported before.

Conclusions. HD 4915 shows a distinctive activity behaviour that was initially attributed to a possible and incipient MM phase. Additional HARPS data allowed us to discard an MM in the star. Our analysis shows that the complex activity pattern of HD 4915 might be ruled by a multiple activity cycle, in which a shorter cycle of 4.8 yr is modulated by a potential longer cycle. More activity surveys with extensive records and suitable cadence are crucial for an accurate identification of stars in magnetic grand minima.
Auralization of atmospheric turbulence-induced amplitude fluctuations in aircraft flyover sound based on a semi-empirical model
Authors: Lincke Dorothea , Pieren Reto
Published: October 2024

Atmospheric turbulence causes well-audible fluctuations in sound amplitude as it propagates through the atmospheric boundary layer. However, the best currently available theoretical model describing amplitude fluctuations is limited to relatively short propagation distances and weak turbulence. This article presents a semi-empirical model for predicting the standard deviation of amplitude fluctuations, combining the existing theoretical model of Ostashev and Wilson with empirical data. Leveraging a dataset of over 5000 aircraft flyovers across diverse meteorological conditions, the model incorporates factors such as frequency- and distance-dependent saturation of amplitude fluctuations, an effective propagation length based on the boundary layer height, turbulence decay time during transitional states of the atmosphere, and turbulence production by nocturnal low-level-jets. The mean absolute error of the semi-empirical model compared to the measurements is 0.4 dB. The application of the semi-empirical model to aircraft auralization is demonstrated for a flyover in two meteorological conditions. The findings will enhance the modeling of outdoor sound propagation for elevated sound sources like aircraft and wind turbines. Enhanced modeling of these fluctuations can considerably improve the realism of the listening experience in aircraft flyover auralization. Further, it helps estimating the measurement uncertainty in measured aircraft noise, particularly for maximum levels.
Low lidar ratios at elevated depolarization ratios in Dushanbe – Revisited using a time–height resolved air mass source attribution tool
Authors: Hofer Julian , Althausen Dietrich , Ansmann Albert , Abdullaev Sabur F. , Makhmudov Abduvosit N. , Lipken Friederike , Jimenez Cristofer , Baars Holger , Engelmann Ronny , Radenz Martin
Published: October 2024

First ever lidar observation in Tajikistan were conducted during the Central Asian Dust Experiment 2015–2016 (CADEX) in Dushanbe. Analysis of layer-mean optical properties revealed frequently low lidar ratios at enhanced depolarization ratios. These cases were categorized as background aerosol since they occurred at low extinction conditions. Such optical properties are similar to dried and therefore cubic-like shaped sea salt particles. This led to the hypothesis that Central Asian background aerosol and its optical properties are influenced by dry lakes and saline playas which are frequent in Central Asia. The goal of this study is to extend the existing data analysis with a backward trajectory-based time– height resolved air mass source attribution tool which was not yet available at the time of the CADEX campaign and its data analysis. Despite on average similar air mass origins for all cases irrespective of their optical properties, results suggest slightly more southern and south-western influenced air masses for cases with larger lidar ratios than for cases with lower lidar ratios.
Investigations into the role of electrostatics in the transport of dust particles
Authors: Lacks Daniel
Published: October 2024

We describe the results of three sets of laboratory experiments that were carried out to elucidate the role of electrostatic forces in dust transport. First, we address the lifting of particles in an electric field; we determine the charges of individual particles that are lifted, and by showing that these charges are in quantitative agreement with a first principles (no-fitting-parameter) model, we demonstrate that neutral particles can be lifted by an induction mechanism. Second, we address the trajectory of already-lofted particles in an electric field, and show that the electric field acts to enhance the concentration of larger particles at higher elevations. Third, we address the time-scale of the decay of charge on particles, in regard to the question of the relevance of charge on long-distance dust transport; we show that, at least under certain circumstances, charge can remain on particles for days to weeks.
Frequency of occurrence of atmospheric parameters according to AERONET data in Dushanbe
Authors: Makhmudov Abduvosit N. , Abdullaev Sabur F. , Maslov Vladimir A.
Published: October 2024

One of the main factors causing climate and weather changes is dust aerosol in the air. The article analyzes the interannual variation in the occurrence of atmospheric parameters (aerosol optical depth (AOD), water vapor (humidity) content (W) and the Ångström parameter (α), obtained from systematic measurements at the AERONET station in Dushanbe. A comparative analysis of the frequency of occurrence of atmospheric parameters according to AERONET data in the period from 2019 till 2022 years. The main reasons for changes of annual variation of aerosol parameters are meteorological factors, and changes in the dispersed structure of aerosol particles of different origins. The distribution contours of AOD and α have a singlemode character, variations of W are much wider and more diverse and do not have a pronounced form with characteristic contours of occurrence frequency for interannual values of AOD and α. The constructed frequency histograms make it possible to assess the dynamics of atmospheric parameters and predict the state of the entire climate system.
Characteristics of aerosol types and identifying the external dust sources (the case of Mashhad city, Iran)
Authors: Rashki Alireza , Feizollahi Somayeh , Bayat Ali
Published: October 2024

Aerosols, consisting of solid, liquid, and gaseous particles, emerge from both natural and humaninduced origins, impacting air quality over substantial distances. This investigation focuses on discerning dust origins in the polluted city of Mashhad, Iran. Crucial parameters, such as aerosol optical thickness (AOT) and Ångström exponent (AE), play a vital role in understanding aerosols and atmospheric pollutants. Ground-based sun photometers (Calitoo) were employed for calculating AOT and AE at different wavelengths to determine the aerosol characteristics and to reveal the prevalence of urban-industrial pollution. The research detect dust and identifies dust sources from both domestic and neighboring deserts, noting seasonal variations. The results highlight the importance of comprehensive monitoring and understanding of aerosol dynamics for effective air quality management.
Assessment of the transfer of the dust-sand-salt material from the dry bottom of the Aral Sea
Authors: Rafikov Vahob
Published: October 2024

The study of the Aral Sea and its impact on the natural environment of the adjacent areas is one of the long-standing problems of hydrometeorology. Around the middle of the last century, individual scientists and then individual institutions took part in these studies, but the most thorough study of the Aral Sea and its basin began in the late 1950s – early 1960s of the last century. The existence of the Aral Sea is almost entirely determined by the inflow of river water into it. A significant decrease in the volume of flow in the Amu Darya and Syr Darya basins, the waters of which are taken for irrigation of huge crop areas (about 7 million hectares), is the main reason for the steady decline in sea level. Irretrievable flow withdrawals have already completely exhausted the compensatory capacity of these rivers and led to the disruption of water and salt balances. By the beginning of 1990, the area of the Aral Sea was decreasing by 1.8 and 2.8 times compared to long-term averages, with the level dropping by 14.3 meters compared to 1961. If the rate of level fall remains the same, by 2030 the level will have fallen by about 18 metres. This rapid recession has exposed large areas of the sea floor. In 1980, the area of formed land reached about 10 thousand km2, and in 1990 27 thousand km2, and in 2020 56 thousand km2 and the former Aral Sea bed became a source of sand, dust and salts. The open surfaces of saline soils of light mechanical composition began to undergo intensive weathering processes, which led to the development of dust-salt storms and the transport of dust and salt aerosol to the adjacent territories of the Republic of Kazakhstan and Central Asia, including irrigated farming massifs in the Amu Darya and Syr Darya deltas. Visible dust-salt plumes detected from artificial Earth satellites are several hundred kilometres long. This indicates the large-scale nature of the process of solid phase particles entering the atmosphere, as well as their prolonged transformation in the suspended state. The article considers the issues of assessment of dust-sand-salt material transport from the dried Aral Sea bed, as well as the conditions of origin and development, their dynamics, local structure, distribution areas and others.
Assessment of salt and sand migration rising from the drying bottom of the Aral Sea based on space research methods
Authors: Kuzyev Farhod
Published: October 2024

This article focuses on monitoring the environmental impact of salt, dust and sand migration rising from the dry bottom of the Aral Sea, evaluating it based on multi-year space images and GIS technologies and systematic analysis methods.