bluuebunny/crossref_metadata_2025 huggingface dataset:
Evolution of a nanoflare-scale magnetic reconnection event in the quiet Sun
Authors: Robinson Rebecca A.
Published: December 2024

Low-lying loops in the quiet Sun are a reliable source of energy for atmospheric heating, but the mechanisms by which they evolve are somewhat enigmatic. To address the origins of atmospheric heating events in the quiet Sun, we utilize our stratified, convection-driven, 3D MHD simulation Bifrost to explore the evolution and eventual major reconnection between several magnetic features; one of which is a magnetic flux rope. We zoom in on the buildup of the magnetic flux rope, which self-orders in the corona via an inverse cascade of helicity. We also discover that the flux rope attempts to relax to a linear force-free field according to Taylor’s theory, but cannot do so completely. Finally, we demonstrate that the eventual nanoflare-scale reconnection event could potentially be observed in the 171 Å channels of SDO/AIA and the future MUSE mission. We also determine that the spectral resolution of MUSE is sensitive enough to capture the kinematics of the bi-directional plasma jets emanating from the reconnection region.
Center-to-limb variation of spectral lines and their effect on full-disk observations
Authors: Pietrow Alexander G. M. , Pastor Yabar Adur
Published: December 2024

An accurate description of the center-to-limb variation (CLV) of stellar spectra is becoming an increasingly critical factor in both stellar and exoplanet characterization. In particular, the CLV of spectral lines is extremely challenging as its characterization requires highly detailed knowledge of the stellar physical conditions. To this end, we present the Numerical Empirical Sun-as-a-Star Integrator (NESSI) as a tool for translating high-resolution solar observations of a partial field of view into disk-integrated spectra that can be used to test common assumptions in stellar physics.
The role of nonlinear toroidal flux loss due to flux emergence in the long-term evolution of the solar cycle
Authors: Biswas Akash
Published: December 2024

A striking feature of the solar cycle is that at the beginning, sunspots appear around mid-latitudes, and over time the latitudes of emergences migrate towards the equator. The maximum level of activity varies from cycle to cycle. For strong cycles, the activity begins early and at higher latitudes with wider sunspot distributions than for weak cycles. The activity and the width of sunspot belts increase rapidly and begin to decline when the belts are still at high latitudes. However, in the late stages of the cycles, the level of activity, and properties of the butterfly wings all have the same statistical properties independent of the peak strength of the cycles. We have modelled these features using Babcock–Leighton type dynamo model and shown that the toroidal flux loss from the solar interior due to magnetic buoyancy is an essential nonlinearity that leads to all the cycles decline in the same way.
AutoTAB: An Algorithm to Track Bipolar Magnetic Regions and Initial results from the Tracked BMRs
Authors: Sreedevi Anu , Jha Bibhuti Kumar , Karak Bidya Binay , Banerjee Dipankar
Published: December 2024

AutoTAB is a state-of-the-art, fully automatic algorithm that tracks the Bipolar Magnetic Regions (BMRs) in magnetogram observations. AutoTAB employs identified BMR regions from Line-of-Sight magnetograms from MDI and HMI (1996–2022) to track the BMRs through their evolution on the nearside of the Sun. AutoTAB enables us to create a comprehensive and unique catalog of tracked information of 9232 BMRs in the mentioned time period. This dataset is used to study the collective statistical properties of BMRs and particularly to identify the correct theory for the BMR formation. Here, we discuss the algorithm’s functionality and the initial findings obtained from the AutoTAB BMRs catalog.
Exploring the Quenching of Bipolar Magnetic Region Tilts using AutoTAB
Authors: Jha Bibhuti Kumar , Sreedevi Anu B. , Karak Bidya Binay , Banerjee Dipankar
Published: December 2024

The tilt of the bipolar magnetic region (BMR) is crucial in the Babcock-Leighton process for the generation of the poloidal magnetic field in the Sun. We extend the work of Jha et al. (2020) and analyze the recently reported tracked BMR catalogue based on AutoTAB (Sreedevi et al. 2023) from Michelson Doppler Imager (1996–2011) and Helioseismic and Magnetic Imager (2010–2018). Using the tracked information of BMRs based on AutoTAB, we confirm that the distribution of Bmax reported by Jha et al. (2020) is not because of the BMRs are picked multiple times at the different phases of their evolution instead it is also present if we consider each BMRs only once. Moreover, we find that the slope of Joy’s law (〈γ0〉) initially increases slowly with the increase of Bmax. However, when Bmax >2.5 kG, γ0 decreases. The decrease of observed γ0 with Bmax provides a hint to a nonlinear tilt quenching in the Babcock-Leighton process.
Thermal instability in the impulsive phase of solar flares with sub-THz component
Authors: Smirnova V. V. , Tsap Yu. T. , Motorina G. G. , Morgachev A. S. , Bárta M.
Published: December 2024

Coronal rain is formed in the post-impulsive phase of solar flares due to the thermal instability of coronal plasma in EUV loops. As a result, the sub-terahertz (sub-THz) emission flux in the post-impulsive phase of solar flares can be increased due to the increasing of the optical thickness of the thermal source. This suggests that sub-THz observations can be used as a diagnostic tool for coronal rain.

This work is aimed to analyse the relationship between the sub-THz radiation and variations of the temperature and the emission measure of the EUV coronal plasma during the post-impulsive phase of the SOL2022-05-04T08:45 solar flare.

Based on the two-dimensional temperature and emission measure distributions obtained from the AIA/SDO EUV intensity data, it was found that the temperature decreases whereas the emission measure reaches the maximum near the sub-THz flare peak. This circumstance and peculiarities of the radiation time profiles in different wave ranges show evidence in favor of the significant contribution of the thermal coronal loop plasma to the flare sub-THz radiation at least for some flare events. The sub-THz emission may be associated with a coronal condensation, accompanied by the formation of coronal rain.
Effects of rotation and surface forcing on deep stellar convection zones
Authors: Käpylä Petri J.
Published: December 2024

The canonical undestanding of stellar convection has recently been put under doubt due to helioseismic results and global 3D convection simulations. This “convective conundrum” is manifested by much higher velocity amplitudes in simulations at large scales in comparison to helioseismic results, and the difficulty in reproducing the solar differential rotation and dynamo with global 3D simulations. Here some aspects of this conundrum are discussed from the viewpoint of hydrodynamic Cartesian 3D simulations targeted at testing the rotational influence and surface forcing on deep convection. More specifically, the dominant scale of convection and the depths of the convection zone and the weakly subadiabatic – yet convecting – Deardorff zone are discussed in detail.
Levels of stabilization of velocity and magnetic induction in the convective zone of the Sun
Authors: Starchenko S. V.
Published: December 2024

The induction and momentum equations of solar dynamo are simplified to a dynamic system for the convective Root-Mean-Square (rms) velocity and the rms magnetic field in the solar convection zone. The study of stable stationary points of this system gives a minor excess of the critical level of the dynamo and, accordingly, moderate magnetic field typically about 1 T (10 kG). A significantly lower rms magnetic field may be possible at some parameters of the system. The stable rms velocity is about 100 m/sec, and the characteristic magnetic times are about the half-period of solar rotation or about an average lifetime of sunspots. Relative magnetic energy is of order 5 kJ/kg that is about the kinetic energy. The unstable stationary points could be near zero magnetic fields as in periods of very lower solar activity similar to the Maunder minimum.
Sub-THz emission from stellar flares and energy release diagnostics
Authors: Tsap Yuriy T. , Stepanov Alexander V. , Melnikov Victor F.
Published: December 2024

A comparative analysis of sub-THz emission of stellar flares from red dwarfs has been carried out. ALMA observations indicate that the sub-THz emission flux from stellar flares with a duration of 10 s is an order of magnitude greater than for solar flares. The sub-THz emission is linearly polarized and decreases with frequency. The degree of polarization can reach tens of percent. We show that these types of spectrum slopes and linear polarization can be caused by the synchrotron emission of ultrarelativistic electrons. The origin of the observed relationships between sub-THz, low frequency radio, and X-ray emissions of stellar flares are discussed.
Magnetic field and radial velocity fluxes at the initial stages of the evolution of solar active regions based on measurements at the photospheric level
Authors: Sadykov A. M. , Krasotkin S. A.
Published: December 2024

In this article, the physical processes occurring in the convective layer and the photosphere of the Sun and their connection to the formation of active regions (ARs) and the development of the corresponding magnetic field are explored. Specifically, we test the magnetic flux emergence hypothesis and based on the line-of-sight magnetic field and Doppler shift data obtained from the Global Oscillation Network Group (GONG) observations. The study encompasses the analysis of 24 ARs observed during the period from 2011 to 2022. We find a strong correlation between the magnetic flux and the imbalance of radial velocity fluxes. The results indicate that the magnetic flux emergence hypothesis cannot fully explain the evolution of ARs during their early stages of development.
Convection, rotation, and magnetic activity of solar-like stars from asteroseismology
Authors: Mathur Savita
Published: December 2024

During the last decade, our understanding of stellar physics and evolution has undergone a tremendous revolution thanks to asteroseismology. Space missions such as CoRoT, Kepler, K2, and TESS have already been observing millions of stars providing high-precision photometric data. With these data, it is possible to study the convection of stars through the convective background in the power spectrum density of the light curves. The properties of the convective background or granulation has been shown to be correlated to the surface gravity of the stars. In addition, when we have enough resolution (so long enough observations) and a high signal-to-noise ratio (SNR), the individual modes can be characterized in particular to study the internal rotational splittings and magnetic field of stars. Finally, the surface magnetic activity also impacts the amplitude and hence detection of the acoustic modes. This effect can be seen as a double-edged sword. Indeed, modes can be studied to look for magnetic activity changes. However, this also means that for stars too magnetically active, modes can be suppressed, preventing us from detecting them.

In this talk, I will present some highlights on what asteroseismology has allowed us to better understand the convection, rotation, and magnetism of solar-like stars while opening doors to many more questions.
Nonlinear and stochastic mechanisms of the solar cycle and their implications for the cycle prediction
Authors: Jiang Jie
Published: December 2024

Solar activity shows an 11-year (quasi)periodicity with a pronounced, but limited variability of the cycle amplitudes. The properties of active region (AR) emergence play an important role in the modulation of solar cycles and are our central concern in building a model for predicting future cycle(s) in the framework of the Babcock–Leighton (BL)-type dynamo. The emergence of ARs has the property that strong cycles tend to have higher mean latitudes and lower tilt angle coefficients. Their non-linear feedbacks on the solar cycle are referred to as latitudinal quenching and tilt quenching, respectively. Meanwhile, the stochastic properties of AR emergence, e.g., rogue ARs, limit the scope of the solar cycle prediction. For physics-based prediction models of the solar cycle, we suggest that uncertainties in both the observed magnetograms assimilated as the initial field and the properties of the AR emergence should be taken into account.
A Frequency-Dependent Method for Measuring the Sun’s Interior Meridional Circulation
Authors: Chen Ruizhu , Zhao Junwei
Published: December 2024

The Sun’s meridional circulation is a crucial component for understanding the Sun’s dynamo and its interior dynamics. However, the determination of meridional circulation is affected by a systematic center-to-limb (CtoL) effect, which introduces systematic errors 5–10 times stronger than the meridional-flow-induced travel-time shifts in deep-flow measurements. Recently, it was found that the CtoL effect has a significant acoustic-frequency dependence, while flow-induced travel-time shifts show little frequency dependence (Chen & Zhao 2018). This discovery forms the basis for designing a new method to remove the CtoL effect. We therefore propose a frequency-dependent approach to measure the CtoL effect and the flow-induced signals in the Fourier domain. In this work, we present this new method and compare time–distance measurements in different frequency bands with those obtained by previous time-domain methods. The results demonstrate consistency with conventional time-domain fitting methods in the dominant frequency range, promising the potential for conducting meridional flow inversion across a broader frequency spectrum.
Complexity of emerging magnetic flux during lifetime of solar ephemeral regions
Authors: Yang Hanlin
Published: December 2024

As a relatively active region, ephemeral region (ER) exhibits highly complex pattern of magnetic flux emergence. We aim to study detailed secondary flux emergences (SFEs) which we define as bipoles that their locations close to ERs and finally coalesce with ERs after a period. We study the SFEs during the whole process from emergence to decay of 5 ERs observed by the Helioseismic and Magnetic Imager (HMI) aboard Solar Dynamics Observatory (SDO). We find that the maximum unsigned magnetic flux for each of the ERs is around 1020 Mx. All ERs have tens of SFEs with an average emerging magnetic flux of approximately 5×1018 Mx. The frequency of normalized magnetic flux for all the SFEs follows a power law distribution with an index of -2.08. The majority of SFEs occur between the positive and negative polarities of ER, and their growth time is concentrated within one hour. The magnetic axis of SFEs also exhibits a random characteristic. We suggest that the relationship between SFEs and ERs can be understood by regarding the photospheric magnetic field observations as cross-sections of an emerging magnetic structure. Tracking the ERs’ evolution, we propose that the flux emergences are partially emerged Ω-loops, and that the SFEs in ERs may be sequent emergences from the bundle of flux tube of ERs.
Understanding Grand Minima in Solar Activity: Confronting Observations with Dynamo Simulations
Authors: Saha Chitradeep , Nandy Dibyendu
Published: December 2024

The grand minimum in the Sun’s activity is a distinctive mode characterized by a magnetic lull that almost completely lacks the emergence of sunspots on the solar surface for an extended duration. The factors driving this transition of an otherwise magnetically active star into a quiescent phase, the processes occurring within the solar interior and across the heliosphere during this period, and the mechanisms leading to the eventual resurgence of surface magnetic activity remain enigmatic. However, there have been sustained efforts in the past few decades to unravel these mysteries by employing a combination of observation, reconstruction and simulation of solar magnetic variability. Here, we summarize recent research on the solar grand minimum and highlight some outstanding challenges – both intellectual and practical – that necessitate further investigations.
Subsurface Flows Associated with Formation and Flaring Activity of Solar Active Regions
Authors: Kosovichev Alexander G. , Sadykov Viacheslav M.
Published: December 2024

We investigate the evolution of subsurface flows during the emergence and the active phase of sunspot regions using the time–distance helioseismology analysis of the full-disk Dopplergrams from the Helioseismic and Magnetic Imager (HMI) onboard the Solar Dynamics Observatory (SDO). We present an analysis of emerging active regions of various types, including delta-type active regions and regions with the reverse polarity order (‘anti-Hale active regions’). The results reveal strong vortical and shearing flows during the emergence of magnetic flux, as well as the process of formation of large-scale converging flow patterns around developing active regions, predominantly in the top 6 Mm deep layers of the convection zone. Our analysis revealed a significant correlation between the flow divergence and helicity in the active regions with their flaring activity, indicating that measuring characteristics of subsurface flows can contribute to flare forecasting.
Help-Seeking Behavior of Adolescents and Emerging Adults With Mental Health Problems During the COVID-19 Pandemic
Authors: Stelzmann Daniela , Çelik Fatma , Gerhold Lars
Published: December 2024

Abstract: Theoretical Background: The COVID-19 pandemic has negatively impacted the mental health of many adolescents and emerging adults (A and EA). Studies from before the COVID-19 pandemic document that A and EA with mental health problems rarely seek help. At the same time, studies suggest that the COVID-19 pandemic and the associated framework conditions also negatively impacted the help-seeking process for A and EA. Objective: This study provides a research synthesis on A’s and EA’s help-seeking process (in particular, help-seeking behavior) during the COVID-19 pandemic and identifies potential influencing factors on the help-seeking process. Method: We conducted a scoping review in accordance with the framework proposed by Arksey and O’Malley (2005 ) and adhered to the PRISMA Extension for Scoping Reviews Guidelines ( Tricco et al., 2018 ) while analyzing the content of primary studies examining the help-seeking process of A and EA with mental health problems during the COVID-19 pandemic. Results: Fourteen primary studies met the inclusion criteria. The synthesized data indicate that increased psychological stress during the COVID-19 pandemic did not automatically lead to increased help-seeking behavior. Furthermore, we identified several factors influencing help-seeking behavior, such as personal factors (e. g., gender), factors linked to the social environment (e. g., open conversation style within the family), and structural factors (e. g., prolonged waiting periods) that influenced the help-seeking process. Notably, many of these factors had already been identified in prepandemic studies (e. g., gender). Discussion and conclusion: We discuss the results concerning possible prevention measures.
Krisenfest aufwachsen in Zeiten von Klimawandel, Krieg und Pandemie
Authors: Asbrand Julia , Christiansen Hanna
Published: December 2024

Zusammenfassung: Das Aufwachsen im 21. Jahrhundert konfrontiert Kinder und Jugendliche mit globalen Herausforderungen wie den Folgen der COVID-19-Pandemie, wirtschaftlichen Krisen, bewaffneten Konflikten und dem Klimawandel. Diese Krisen verstärken sich gegenseitig und betreffen junge Menschen psychisch stärker als Erwachsene. Diese Belastung zeigt sich insbesondere in erhöhten Depressions- und Angstsymptomen. Trotz des wachsenden Bedarfs an psychischer Gesundheitsversorgung mangelt es an adäquaten Angeboten bei einer Verdoppplung der Wartezeiten. Insgesamt zeigen die Erkenntnisse signifikante negative Auswirkungen globaler Krisen auf die gesunde Entwicklung junger Menschen. Der aktuelle Themenschwerpunkt fasst Erkenntnisse zusammen, wie Krisen auf die psychische und somatische Gesundheit wirken und welche Handlungsmöglichkeiten sich für den Erhaltung und die Wiederherstellung der (psychischen) Gesundheit ergeben.
Comparison of the ENSO‐Related Interannual Variability of the ECS‐Kuroshio Before and After 2005
Authors: Liu Zhao‐Jun , Qiao Yu‐Xiang , Nakamura Hirohiko , Zhu Xiao‐Hua , Nishina Ayako , Zhang Chuanzheng , Zhu Ze‐Nan , Xiao Cong
Published: December 2024

The El Niño‐Southern Oscillation (ENSO)‐related interannual variability of the Kuroshio in the East China Sea (ECS) was revisited based on reanalysis outputs during 1993–2018. Unlike the synchronized variations from 2006 to 2018, the period of 1993–2005 showed regional differences in how the ECS‐Kuroshio responded to ENSO events. Specifically, from the upstream region to the midway of the continental slope, the ECS‐Kuroshio exhibited distinct six‐year interannual modulation during 1993–2005. In contrast, downstream Kuroshio variability primarily followed a four‐year cycle, aligning with ENSO variability during the same period. Further analysis suggested that the sea surface height anomaly (SSHA) east of the Kerama Gap, near the midpoint of the Ryukyu Island chain, extended inside the ECS until the southern side of the Tokara Strait along the ECS‐Kuroshio path and was well correlated with the Kuroshio in the Tokara Strait during 1993–2005. The cause of this SSHA signal was attributed to forcing by ENSO‐related wind stress curl changes in the interior region. There was an obvious difference in the ENSO‐related atmospheric circulation before and after 2005. The wind stress curl pattern in the North Pacific during 1993–2005, characterized by a maximum in the Kerama Gap latitude band, shifted northward compared to that during 2006–2018. The relative northward shift of the ENSO‐related wind stress curl, which stimulates the long baroclinic Rossby wave propagating westward and arriving east of the Kerama Gap, affect the interannual variabilities of both the upstream and downstream Kuroshio.
Enhancing the structural and optoelectronic properties of carboxymethyl cellulose sodium filled with ZnO/GO and CuO/GO nanocomposites for antimicrobial packaging applications
Authors: Badry Rania , Sabry Noha M. , Ibrahim Medhat A.
Published: December 2024

One of the biggest challenges in food packaging is the creation of sustainable and eco-friendly packaging materials to shield foods from ultraviolet (UV) photochemical damage and to preserve the distinctive physical, chemical, and biological characteristics of foods throughout the supply chain. Accordingly, this study focuses on enhancing the UV shielding properties and biological activity of carboxylmethyl cellulose sodium (CMC) through modifications using zinc oxide (ZnO), copper oxide (CuO), and graphene oxide (GO) using the solution casting technique. The hybrid nanocomposites were characterized by fourier-transform infrared (FTIR) spectrophotometer, ultraviolet-visible (UV-Vis) spectrophotometer, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and x-ray diffraction (XRD). Significant interactions between CMC and the metal oxide/GO nanocomposites were revealed by FTIR analysis, which reflects the formation of hydrogen bonding between CMC and the nanocomposites. XRD confirmed the functionalization of CMC with ZnO/GO and CuO/GO nanocomposites. Additionally, the CMC film showed a decrease in the optical bandgap from 5.53 to 3.43 eV with improved UV shielding capacity. Moreover, the composite films had excellent refractive index and optical conductivity values of 1.97 and 1.56 × 1010 Ω cm− 1, respectively. SEM and EDX analysis confirmed the formation of ZnO/GO and CuO/GO within the CMC matrix. Thus, dedicates that the CMC nanocomposites have promising applications in packaging materials. These results were confirmed by the quantum mechanical calculations utilizing density functional theory (DFT). Total dipole moment (TDM), frontier molecular orbitals (FMOs), chemical reactivity descriptors, and molecular electrostatic potential (MESP) maps were all studied using the B3LYP/LanL2DZ model. The TDM and FMO investigations revealed that the CMC/CuO/GO model has the highest TDM (84.031 Debye) and the smallest band gap energy (0.118 eV). Moreover, CMC’s reactivity increased after CuO/GO nanocomposites integration, as demonstrated by MESP mapping. Finally, the antibacterial activity of pure CMC, CMC/ZnO/GO, and CMC/CuO/GO nanocomposite films was evaluated against Staphylococcus aureus and Escherichia coli. The zones of inhibition data showed that both CMC/ZnO/GO and CMC/CuO/GO exhibited higher antibacterial activity than CMC alone, particularly against S. aureus. The inhibition zones for CMC/ZnO/GO and CMC/CuO/GO against S. aureus were 16 mm and 14 mm, respectively, suggesting enhanced susceptibility of S. aureus compared to E. coli. These results highlight the significant potential of ZnO and CuO NPs in improving the antimicrobial efficacy of CMC nanocomposites.
Drug carrier-assisted combined chemo- and radionuclide therapy for tumors of diverse origins: effects of therapeutic schemes on tumor responses
Authors: Postovalova Alisa S. , Akhmetova Darya R. , Rogova Anna , Sivak Konstantin V. , Gavrilova Nina V. , Zabrodskaya Yana A. , Rusakova Vladislava A. , Tishchenko Yulia A. , Shipilovskikh Sergei A. , Timin Alexander S.
Published: December 2024

We performed a systematic investigation on the development of combined chemo- and radionuclide therapy for the treatment of three tumor types of different origins: colorectal cancer (CT26), melanoma (B16-F10), and breast cancer (4T1).
Heterobimetallic contacts in statistical co-crystals of homoleptic coordination compounds with ligand-encoded H⋯F bonds: structure, photophysics and mechano-responsive properties
Authors: Theiss Tobias , Buss Stefan , Maisuls Iván , Block Theresa , Kösters Jutta , Pöttgen Rainer , Strassert Cristian A.
Published: December 2024

In this work, the structural and photophysical characterization of statistical co-crystals based on two homoleptic Pt(ii) and Pd(ii) complexes as well as their mechano-responsive properties are reported.
Design of an anti-PD-L1-mediated MOF nanodrug delivery system using terpyridine-metal coordination for tumor theranostics
Authors: Han Xu , Chen Jia , Cheng Zhihao , Zhou Shengwang
Published: December 2024

Anti-PD-L1 was anchored to the MOF surface through Tpy-Gd3+-Tpy coordination, constructing a nanodrug delivery system for combination therapy and multimodal imaging.
Fluorinated organosilane polycondensation enables a robust Si anode for lithium storage
Authors: Li Zhengyue , Huang Jiecheng , Wang Zhiyu
Published: December 2024

The chemistry of fluorinated organosilane polycondensation is harnessed to form a robust Si anode with F-doped SiOx/C composite coating, enabling a Si anode with a long life of 500 cycles at large current densities for lithium storage.
The formation mechanism of metal cluster fullerenes Sc3N@Cn: force field development and molecular dynamics simulations
Authors: Fan Huichen , Gan Li-Hua , Wang Chun-Ru
Published: December 2024

The formation of Sc-based metal cluster fullerenes.
First-principles investigation of the photocatalytic properties of two-dimensional CdO/ZrSSe heterojunctions
Authors: Ma Deming , Hui Xiaohan , Yang Xiaoyu , Fu Yuhui , Cui Zhen , Zhang Lin , Ji Weili , Shen Yang , Li Enling
Published: December 2024

CdO/ZrSSe heterojunctions, designed via first-principles calculations, show enhanced photocatalytic hydrogen production with strain-tunable band structures, high carrier mobility, and Z-scheme mechanisms.
Dissipative particle dynamics parametrisation using infinite dilution activity coefficients: the impact of bonding
Authors: Hendrikse Rachel L. , Amador Carlos , Wilson Mark R.
Published: December 2024

In dissipative particle dynamics, the overlap between bonded beads affects their chemical potential, which must be considered when defining parameterisations.
Chemical process of hydrogen and formic acid on a Pd-deposited Cu(111) surface studied by high-resolution X-ray photoelectron spectroscopy and density functional theory calculations
Authors: Osada Wataru , Hasegawa Masahiro , Shiozawa Yuichiro , Mukai Kozo , Yoshimoto Shinya , Tanaka Shunsuke , Kawamura Mitsuaki , Ozaki Taisuke , Yoshinobu Jun
Published: December 2024

In the chemical process of formic acid on Pd–Cu(111), the unique interactions between a Pd atom and adsorbates were elucidated by HR-XPS and DFT calculations.
Balancing enthalpy and entropy in inhibitor binding to the prostate-specific membrane antigen (PSMA)
Authors: Xiong Yuqing , Wang Xinlin , Cui Mengchao , Liu Yajun , Wang Beibei
Published: December 2024

A series of PSMA inhibitors were synthesized and characterized using experimental and computational methods. Microsecond MD simulations reveal the molecular mechanism in modulating binding affinity and selectivity structurally and thermodynamically.
Revealing the catalytic oxidation mechanism of CO on α-Fe2O3 surfaces: an ab initio thermodynamic study
Authors: Song Yun-Hyok , Kye Yun-Hyok , Pang Myong-Il , Ho Yong-Min , Choe Hyon-Chol , Yu Chol-Jun , Ri Chol-Yong
Published: December 2024

We investigated the phase diagram of Fe2O3(0001) surfaces with various terminations and the catalytic mechanism of CO oxidation on these surfaces using an ab initio thermodynamic method within the density functional theory framework.
Innovations and fundamentals in visible light-driven photocatalysis for CO2 reduction
Authors: Sahu Rajesh , Patodia Tarun , Juyal Sakshi , Gill Fateh Singh , Prasad Brijesh , Jain Ankur
Published: December 2024

Fundamental principles of semiconductor photocatalysts for CO2 reduction.
Comparison of greenness and whiteness of selected mechanochemical and solution-based reactions using a new RGBsynt model
Authors: Nowak Paweł Mateusz , Kamiński Michał , Trybała Wojciech , Canale Vittorio , Zajdel Paweł
Published: December 2024

RGBsynt as a new tool for comparing and evaluating synthesis methods in terms of the green and white chemistry concepts.
Fluorescence tunable carbon dots for in vitro nuclear dynamics and gastrointestinal imaging in live zebrafish and their in vivo toxicity evaluation by cardio-craniofacial disfunction assessment
Authors: Dutta Bijaideep , Waghmare Ashwini , Das Sourav Kumar , Bhargava Yogesh , Kumar Amit , Debnath A. K. , Barick K. C. , Hassan P. A.
Published: December 2024

Synthesis of high-performance N-doped carbon dots (TNCDs) with an enhanced quantum yield for dual imaging and their in vivo toxicity evaluation in a zebrafish model.
Aziridine-based organocatalytic polymerization for tunable sulfur incorporation in polyureas
Authors: Xu Leying , Ju Changzheng , Zheng Jiazi , Chen Qingyong , Zhang Zhen
Published: December 2024

Organocatalytic polymerization of aziridine, isocyanate, and inorganic sulfur enables the synthesis of oligosulfide-functionalized polyureas and poly(thioether urea)s with adjustable sulfur content.
‘Kick-in the head’: high-performance and air-stable mononuclear DyIII single-molecule magnets with pseudo-D6h symmetry from a [1 + 1] Schiff-base macrocycle approach
Authors: Armenis Alexandros S. , Mondal Arpan , Giblin Sean R. , Alexandropoulos Dimitris I. , Tang Jinkui , Layfield Richard A. , Stamatatos Theocharis C.
Published: December 2024

Using the [1 + 1] condensation approach for the preparation of new macrocyclic scaffolds with the phenanthroline-based ‘head’ unit afforded two DyIII monomers with pseudo-D6h symmetry and large energy barriers for the magnetization reversal.
Absolute standard hydrogen electrode potential and redox potentials of atoms and molecules: machine learning aided first principles calculations
Authors: Jinnouchi Ryosuke , Karsai Ferenc , Kresse Georg
Published: December 2024

Constructing a self-consistent first-principles framework that accurately predicts the properties of electron transfer reactions through finite-temperature molecular dynamics simulations is a dream of theoretical electrochemists.
Luminescent cyclometalated gold(iii) complexes covalently linked to metal–organic frameworks for heterogeneous photocatalysis
Authors: Chen Jian-Rui , Zhou Dongling , Liu Yungen , Li Mian , Xiao Yonghong , Huang Xiao-Chun , Che Chi-Ming
Published: December 2024

Phosphorescent gold(iii) complexes possess long-lived emissive excited states, making them ideal for use as photocatalysts for organic transformations.
Gas-flow activation of MOFs: unlocking efficient catalysis through dynamic bonding
Authors: Díaz-Ramírez Mariana L. , Park Sun Ho , Rivera-Almazo Marcos , Medel Erika , Peralta Ricardo A. , Ibarra Ilich A. , Vargas Rubicelia , Garza Jorge , Jeong Nak Cheon
Published: December 2024

Gas-flow activation by inert gases eliminates coordinating solvents under mild conditions, thereby maintaining the structural integrity of MOFs. This finding reveals that dynamic bonding at open-metal sites is the key in facilitating this activation.
Single-isomer bis(pyrrolidino)fullerenes as electron-transporting materials for tin halide perovskite solar cells
Authors: Nakamura Tomoya , Nagai Takabumi , Miyake Yuki , Yamada Takumi , Miura Makoto , Yoshida Hiroyuki , Kanemitsu Yoshihiko , Truong Minh Anh , Murdey Richard , Wakamiya Atsushi
Published: December 2024

We introduce a single-isomer fullerene bisadduct, Bis-PC, as an electron transport material in tin perovskite solar cells. The efficiency reached 12.3%, and the shelf stability was over 3000 h.
An efficient and flexible approach for local distortion: distortion distribution analysis enabled by fragmentation
Authors: Yan Zeyin , Liao Yunteng Sam , Li Xin , Chung Lung Wa
Published: December 2024

A general, efficient and flexible approach based on fragmentation and ONIOM-type boundary strategies aids computational and experimental chemists in visualizing distortion maps and evaluating the local distortion energy of various molecules.
Phase-engineered zirconium MOF-based titanium single-atom catalysts: phase-dependent properties and applications in biodiesel synthesis
Authors: Wu Yanjie , He Jiaxin , Li Xiaodong , Chen Ye , Ke Zhihai
Published: December 2024

The paper presents a study on the development and application of zirconium-based metal–organic framework (Zr-MOF) supported titanium (Ti) single-atom catalysts (SACs).
Accelerated decoding method in fractal image coding
Authors: Wang Qiang
Published: December 2024

To accelerate the fractal decoding process, a minimum domain block set (MDBS)‐based fast fractal decoding method is proposed here. In fractal encoding process, it is found that there exists a MDBS which can provide the best‐matched domain blocks for all range blocks. In the decoding process, MDBS is first identified before the first iteration. Then, only the range blocks inside MDBS are reconstructed in each of the first to penultimate iterations, and the computations of reconstructing the remaining range blocks outside MDBS can be saved to speedup the decoding process. Finally, all range blocks are reconstructed to obtain the decoded image in the last iteration. Experimental results show that about 5%–17% of total computations in decoding process can be saved.
Improved non‐cascaded continuous‐set model‐free predictive control scheme for PMSM drives
Authors: Xu Bowen , Wu Qiyi , Ma Jien , Liu Xing , Fang Youtong
Published: December 2024

This article presents an improved multiple‐step model‐free predictive control (MS‐MFPC) method for permanent magnet synchronous motor (PMSM) drives. Specifically, a reduced‐order MS‐MFPC based on an ultra‐local model, which employs only the input and output of the plant without addressing any motor parameters, is developed to enhance the robustness and reliability of the non‐cascaded PMSM system in the presence of parametric uncertainties. Meanwhile, the decoupled form of algebraic ultra‐local model is derived to extend the prediction horizon to multiple steps without increasing the computational burden. Besides, in order to improve the dynamic performance, an online adaptive modification approach is embedded into this suggested design to enhance the cost function calculation for the first time. Compared with the conventional continuous control set‐model predictive control (CCS‐MPC) method, our development not only achieves the smaller overshoot, settling time and steady‐state error, but also attenuates the inherent issue of system uncertainties in widely existing industrial application. Finally, the proposed MS‐MFPC methodology is experimentally assessed for a PMSM test bench, where steady‐state and transient‐state performance tests confirm the interest of the proposal.
A general polarimetric model for transiting and nontransiting ringed exoplanets
Authors: Veenstra Allard K. , Zuluaga Jorge I. , Alvarado-Montes Jaime A. , Sucerquia Mario , Stam Daphne M.
Published: December 2024

Context. The detection and characterization of exorings (rings around exoplanets) will help us to better understand the origin and evolution of planetary rings in the Solar System and beyond. However, exorings are still elusive, and new and clever methods for identifying them need to be developed and tested.

Aims. We explore the potential of polarimetry as a tool for discovering and characterizing exorings.

Methods. For this purpose, we improved the general publicly available photometric code Pryngles by adding the results of radiative transfer calculations with an adding-doubling algorithm that fully includes polarization. With this improved code, we computed the total and polarized fluxes and the degree of polarization of model gas giant planets with or without rings. Additionally, we demonstrate the versatility of our code by predicting the polarimetric signal of the puffed-up planet HIP 41378 f as if it had an exoring.

Results. Spatially unresolved dusty rings can significantly modify the flux and polarization signals of the light that is reflected by a gas giant exoplanet along its orbit. Rings are expected to have a low polarization signal, but they will decrease the degree of polarization of reflected light when they cast a shadow on the planet and/or block part of the planet. The most diagnostic feature of a ring occurs around the ring-plane crossings when sharp changes in the flux and degree of polarization curves are predicted by our model. When we applied our methods to HIP 41378 f, we found that if it is surrounded by a ring, noticeable changes in the degree of polarization of reflected light will arise. Although the reflected light on the planet cannot yet be directly imaged, the addition of polarimetry to future observations would aid in the characterization of the system.
Modélisation du glissement du barrage de Mirgenbach
Authors: Kham Marc , Alves Fernandes Vinicius , Fry Jean-Jacques , Boutonnier Luc
Published: December 2024

Le glissement du barrage de Mirgenbach qui s’est produit en 1982 est un cas d’étude suffisamment documenté pour être utilisé comme cas de validation de toute analyse numérique de la construction d’un barrage en argile. L’objectif d’une telle validation est de justifier que la méthodologie d’analyse est capable de prédire la rupture de cet ouvrage. Un tel exercice de validation est présenté avec le logiciel d’EDF, Code_Aster (Code_Aster, 2001) et le modèle de comportement quasi-saturé proposé par Boutonnier. L’ANR a financé le projet Terredurable pour développer un cadre d’analyse des sols fins afin d’approfondir et améliorer leur mise en place. Les développements de ce projet s’appuient sur ce modèle quasi-saturé prenant en compte l’air occlus après compactage, dont le domaine d’application est le côté humide de la courbe Proctor (Boutonnier et al., 2015), qui correspond exactement à la pratique de la construction des digues et des barrages. La qualification du logiciel Code_Aster s’est donc inspirée de ce modèle pour justifier la modélisation de la construction des barrages en terre. Cette communication rapporte les principes principaux du modèle quasi-saturé, détaille les hypothèses de modélisation, analyse les résultats et discute leur représentativité.
Machine-learning-assisted optimization of Ga-free type-II superlattices for enhanced vertical hole mobility
Authors: Glennon John , Bellotti Enrico
Published: December 2024

Gaussian process regression is used to develop a model for predicting carrier transport in superlattice (SL) structures grown on GaSb and 6.2 Å substrates. This model is used to search SL structures optimized for enhanced hole transport in the vertical (growth) direction. Nonequilibrium Green’s functions calculations are used to determine the vertical hole mobility of several chosen structures in both ideal and disordered cases. It is demonstrated that the conductivity effective mass can be used in some cases as a qualitative predictor for the relative hole mobility between different structures. However, in the case of disordered SLs, the effective mass must be calculated from quasi-random disordered structures as the results may differ significantly from the ideal case. Ultimately, a methodology for predicting SL structures optimized for high hole transport efficiency in the case of ideal and disordered SLs is demonstrated.
Complex control of polaritons based on optical Stark potential
Authors: Zheng Chuyuan , Coker Kenneth , Zhang Wei Li
Published: December 2024

Effectively controlling exciton–polaritons is crucial for advancing them in optical computation. In this work, we propose utilizing the valley-selective optical Stark effect (OSE) as an all-optical way to achieve the spatiotemporal control of polariton flow. We demonstrate the polarization-selective concentration of polaritons at pre-determined locations by wavefront shaping of the polaritons through an in-plane bar-code potential induced by the OSE, which helps overcome the intra-cavity disorder in potential distribution. In addition, a polariton decoder that converts binary inputs to decimal outputs is proposed by expanding the one-dimensional bar-code potential into a two-dimensional quick-response code potential offering enhanced control and encoding, whose robustness and valley selectivity are demonstrated.
Planar tetracoordinate beryllium in σ-aromatic Li4Be and Na4Be clusters: A missing member in first-octal row planar tetracoordinate family
Authors: Miao Lin-hong , Cui Li-juan , Zhang Huiyu , Orozco-Ic Mesías , Yang Yi-Fan , Pan Sudip , Cui Zhong-hua
Published: December 2024

While planar tetracoordinate (pt) centers have been extensively explored from carbon to other octal-row elements or their heavier analogs, their counterparts involving alkali (A) and alkaline-earth metals (Ae) remain elusive due to the large atomic radius and absence of p orbitals. In this work, we found six hitherto unknown anionic ptA (A4A−) and neutral ptAe (A4Ae) centers through an extensive exploration of potential energy surfaces. The D4h-symmetry ptBe structures in Li4Be and Na4Be emerge as the lowest-energy configurations, and all the other ptA/ptAe structures are higher in energy or saddle points. The global-minimum ptBe structure can be described as Be− with a 2s12px12py1 electronic configuration, forming three σ electron sharing interactions with quartet Li4+/Na4+ motifs. The delocalized σ orbitals contribute to σ aromaticity, thereby enhancing the overall stability of these intriguing title ptBe species. Furthermore, these ptBe systems can be encapsulated within the [n]cycloparaphenylene nanoloop (n = 7, 8) thermochemically spontaneously, without any disturbance in planarity in the ptBe moiety, where the systems get stabilized by a predominant electrostatic interaction between Li4/Na4 and the nanoloop.
Tripartite phonon–magnon–plasmon coupling, parametric amplification, and formation of a phonon–magnon–plasmon polariton in a two-dimensional periodic array of magnetostrictive/plasmonic bilayered nanodots
Authors: Pal S. , Pal P. K. , Fabiha R. , Bandyopadhyay S. , Barman A.
Published: December 2024

Coupling between spin waves (SWs) and other types of waves in nanostructured magnetic media has attracted increased attention in recent years because of the rich physics and the potential to spawn disruptive technologies. Among this family of intriguing phenomena, we recently reported a new one: coupling between SWs and hybridized phonon–plasmon waves, resulting in tripartite coupling of magnons, phonons, and plasmons. Here, this acousto-plasmo-magnonic phenomenon is studied in a two-dimensional periodic array of bilayered Co/Al nanodots on a silicon substrate, where Co is a magnetostrictive constituent responsive to magnetoelastic coupling and Al acts as a source of surface plasmons. Time-resolved magneto-optical-Kerr-effect microscopy revealed parametric amplification and strong coupling between two SW modes mediated by a hybrid phonon–plasmon mode. The strong coupling forms a new quasi-particle: the phonon–plasmon–magnon polariton.
Quasi-BIC realized in a subwavelength volumetric split ring-based resonator
Authors: Geyman Sergey V. , Puchnin Viktor M. , Slobozhanyuk Alexey P. , Rybin Mikhail V. , Shchelokova Alena V.
Published: December 2024

In recent years, resonant structures with quasi-bound states in the continuum (quasi-BICs) have significantly expanded the practical possibilities in optics and nanophotonics. A similar mode, the so-called supercavity mode, observed in single dielectric cylinders with high permittivity and low material losses, allows achieving extremely high quality (Q) factors. Resonators supporting quasi-BICs are also promising for applications in the radio frequency range. However, creating compact structures using high-permittivity materials at frequencies below 300 MHz is challenging. This study introduces a subwavelength (∼λ/13) volumetric structure composed of two arrays of coupled split ring resonators, with one array located inside the other, which provides a supercavity mode. The numerical Q factor of this mode is increased by approximately 100 times under lossless conditions and by about 1.5 times when accounting for material losses compared to that of non-interacting modes of the two arrays. The Q factor enhancement is confirmed experimentally by near-field measurements. The advantages of the proposed resonator include its hollow cavity, ease of fabrication, and frequency tunability within the radio frequency range.
A modular and extensible CHARMM-compatible model for all-atom simulation of polypeptoids
Authors: Berlaga Alex , Torkelson Kaylyn , Seal Aniruddha , Pfaendtner Jim , Ferguson Andrew L.
Published: December 2024

Peptoids (N-substituted glycines) are a class of sequence-defined synthetic peptidomimetic polymers with applications including drug delivery, catalysis, and biomimicry. Classical molecular simulations have been used to predict and understand the conformational dynamics of single chains and their self-assembly into morphologies including sheets, tubes, spheres, and fibrils. The CGenFF-NTOID model based on the CHARMM General Force Field has demonstrated success in accurate all-atom molecular modeling of peptoid structure and thermodynamics. Extension of this force field to new peptoid side chains has historically required reparameterization of side chain bonded interactions against ab initio data. This fitting protocol improves the accuracy of the force field but is also burdensome and precludes modular extensibility of the model to arbitrary peptoid sequences. In this work, we develop and demonstrate a Modular Side Chain CGenFF-NTOID (MoSiC-CGenFF-NTOID) as an extension of CGenFF-NTOID employing a modular decomposition of the peptoid backbone and side chain parameterizations, wherein arbitrary side chains within the large family of substituted methyl groups (i.e., –CH3, –CH2R, –CHRR′, and –CRR′R″) are directly ported from CGenFF. We validate this approach against ab initio calculations and experimental data to develop a MoSiC-CGenFF-NTOID model for all 20 natural amino acid side chains along with 13 commonly used synthetic side chains and present an extensible paradigm to efficiently determine whether a novel side chain can be directly incorporated into the model or whether refitting of the CGenFF parameters is warranted. We make the model freely available to the community along with a tool to perform automated initial structure generation.