bluuebunny/crossref_metadata_2025 huggingface dataset:
A novel artificial neural network approach for residual life estimation of paper insulation in oil‐immersed power transformers
Authors: Nezami Md. Manzar , Equbal Md. Danish , Ansari Md. Fahim , Alotaibi Majed A. , Malik Hasmat , García Márquez Fausto Pedro , Hossaini Mohammad Asef
Published: December 2023

Avoiding financial losses requires preventing catastrophic oil‐filled power transformer breakdowns. Continuous online transformer monitoring is needed. The authors use paper insulation to evaluate transformer health for continuous online transformer monitoring. The study suggests a new artificial intelligence method for estimating paper insulation residual life in oil‐immersed power transformers. The four artificial intelligence models use backpropagation‐based neural networks to predict paper insulation lifespan. Four primary transformer insulating paper failure indices—degree of polymerisation, 2‐furfuraldehyde, carbon monoxide, and carbon dioxide—form the basis of these models. Each model, including the backpropagation‐based neural networks, estimates paper insulation life using one failure index, along with moisture and temperature data. Optimisation techniques enhance hidden layer neurons and epoch count for improved performance. Results are validated against literature‐based life models, establishing a precise input–output correlation. This method accurately predicts the remaining useable life of power transformer paper insulation, enabling utilities to take proactive measures for safe and efficient transformer operation.
Optimisation of topology, rating, control and insulation coordination of a large series–parallel DC windfarm
Authors: Shehu Ibrahim Ahmad , Jovcic Dragan , Li Peng
Published: December 2023

This study presents the design of a large DC series‐parallel windfarm that considers the key operational challenges in determining the optimal generator equipment rating and DC transmission voltage control. With this topology, offshore platform is not needed, but wind speed dispersion over windfarms and generator outage possibilities demand generator DC output voltages beyond their ratings. An optimization algorithm is developed along with a complete cost model, which includes operational and capital costs with all topology options, in order to inform design decisions. The results are evaluated on a 100‐generator, 25 × 4, 1 GW, 525 kV test wind farm and performance is verified using detailed PSCAD/EMTDC time‐domain simulation. The key finding is that a positive net present value (NPV) is achieved, avoiding power curtailment even under 3% generator outage, when an overvoltage coefficient of 1.145 pu is utilised on all wind generators, assuming use of a suitable DC transmission voltage control. Further, a wide‐ranging parameter sensitivity analysis is performed, and tower arrangement for insulation requirements is proposed.
Formation of flattened planetesimals by gravitational collapse of rotating pebble clouds
Authors: Lorek Sebastian , Johansen Anders
Published: December 2023

Planetesimals are believed to form by the gravitational collapse of aerodynamically concentrated clumps of pebbles. Many properties of the objects in the cold classical Kuiper belt – such as binarity, rotation, and size distribution – are in agreement with this gravitational collapse model. Further support comes from the pebble-pile structure inferred for comet nuclei. For this study, we simulated the final assembly of a planetesimal from the gravitational collapse of a rotating clump of pebbles. We implemented a numerical method from granular dynamics to follow the collapse that includes the transition from a pebble swarm to solid cells at a high density. We compared the shapes of the simulated planetesimals with the shapes of the lobes of contact binaries and bilobed Solar System objects. We find that the gravitational collapse of slowly rotating pebble clouds naturally explains the formation of flattened ellipsoidal bodies. This result agrees well with the flattened structure of the bilobed planetesimal Arrokoth and the shapes of the components of bilobed comets.
The automatic identification and tracking of coronal flux ropes
Authors: Wagner A. , Bourgeois S. , Kilpua E. K. J. , Sarkar R. , Price D. J. , Kumari A. , Pomoell J. , Poedts S. , Barata T. , Erdélyi R. , Oliveira O. , Gafeira R.
Published: December 2023

Context. Constructing the relevant magnetic field lines from active region modelling data is crucial to understanding the underlying instability mechanisms that trigger the corresponding eruptions.

Aims. We present a magnetic flux rope (FR) extraction tool for solar coronal magnetic field modelling data that builds upon a recent methodology. The newly developed method is then compared against its previous iteration. Furthermore, we apply the scheme to magnetic field simulations of active regions AR12473 (similar to our previous study) and AR11176. We compare the method to its predecessor and study the 3D movement of the newly extracted FRs up to heights of 200 and 300 Mm, respectively.

Methods.The extraction method is based on the twist parameter Tw and a variety of mathematical morphology (MM) algorithms, including the opening transform and the morphological gradient. We highlight the differences between the methods by investigating the circularity of the FRs in the plane we extract from. The simulations for the active regions are carried out with a time-dependent data-driven magnetofrictional model (TMFM). We investigate the FR trajectories by tracking their apex throughout the full simulation time span.

Results. Comparing the newly developed method to the previous extraction scheme, we demonstrate that this upgrade provides the user with more tools and less a priori assumptions about the FR shape, which in turn leads to a more accurate set of field lines. Despite some differences, both the newly extracted FR of AR12473 and the FR derived with the old iteration of the method show a similar general appearance, confirming that the two methods indeed extract the same structure. The methods differ the most in their emergence and formation stages, where the newly extracted FR deviates significantly from a perfectly circular cross-section (which was the basic assumption of the initial method). The propagation analysis yields that the erupting FR from AR12473 indeed shows stronger dynamics than the AR11176 FR and a significant deflection during its ascent through the domain. The modelling results are also verified with observations: AR12473 is dynamic and eruptive, while AR11176 only features an eruption outside of our simulation time window.

Conclusions. We implemented a FR extraction method, incorporating mathematical morphology algorithms for 3D solar magnetic field simulations of active region FRs. This scheme was applied to AR12473 and AR11176. We find that the clearly eruptive FR of AR12473 experiences significant deflection during its rise. The AR11176 FR appears more stable, though there is still a notable deflection. This confirms that at these low coronal heights, FRs undergo significant changes in the direction of their propagation even for less dynamic cases.
Chemical differences among collapsing low-mass protostellar cores
Authors: Sun Jingfei , Li Xiaohu , Du Fujun , Wang Yao , Tuo Juan , Feng Yanan
Published: December 2023

Context. Organic features lead to two distinct types of Class 0/I low-mass protostars: hot corino sources exhibiting abundant saturated complex organic molecules (COMs) and warm carbon-chain chemistry (WCCC) sources exhibiting abundant unsaturated carbon-chain molecules. Some observations suggest that the chemical variations between WCCC sources and hot corino sources are associated with local environments and the luminosity of protostars.

Aims. We aim to investigate the physical conditions that significantly affect WCCC and hot corino chemistry, as well as to reproduce the chemical characteristics of prototypical WCCC sources and hybrid sources, where both carbon-chain molecules and COMs are abundant.

Methods. We conducted a gas-grain chemical simulation in collapsing protostellar cores, adopting a selection of typical physical parameters for the fiducial model. By adjusting the values of certain physical parameters, such as the visual extinction of ambient clouds (AVamb), cosmic-ray ionization rate (ζ), maximum temperature during the warm-up phase (Tmax), and contraction timescale of protostars (tcont), we studied the dependence of WCCC and hot corino chemistry on these physical parameters. Subsequently, we ran a model with different physical parameters to reproduce scarce COMs in prototypical WCCC sources.

Results. The fiducial model predicts abundant carbon-chain molecules and COMs. It also reproduces WCCC and hot corino chemistry in the hybrid source L483. This suggests that WCCC and hot corino chemistry can coexist in some hybrid sources. Ultraviolet (UV) photons and cosmic rays can boost WCCC features by accelerating the dissociation of CO and CH4 molecules. On the other hand, UV photons can weaken the hot corino chemistry by photodissociation reactions, while the dependence of hot corino chemistry on cosmic rays is relatively complex. The value of Tmax does not affect any WCCC features, while it can influence hot corino chemistry by changing the effective duration of two-body surface reactions for most COMs. The long tcont can boost WCCC and hot corino chemistry by prolonging the effective duration of WCCC reactions in the gas phase and surface formation reactions for COMs, respectively. The scarcity of COMs in prototypical WCCC sources can be explained by insufficient dust temperatures in the inner envelopes that are typically required to activate hot corino chemistry. Meanwhile, the high ζ and the long tcont favors the explanation for scarce COMs in these sources.

Conclusions. The chemical differences between WCCC sources and hot corino sources can be attributed to the variations in local environments, such as AVamb and ζ, as well as the protostellar property, tcont.
Probing initial distributions of orbital eccentricity and disc misalignment via polar discs
Authors: Ceppi Simone , Cuello Nicolás , Lodato Giuseppe , Longarini Cristiano , Price Daniel J. , Elsender Daniel , Bate Matthew R.
Published: December 2023

In a population of multiple protostellar systems with discs, the sub-population of circumbinary discs whose orbital plane is highly misaligned with respect to the binary’s orbital plane constrains the initial distribution of orbital parameters of the whole population. We show that by measuring the polar disc fraction and the average orbital eccentricity in the polar discs, one can constrain the distributions of initial eccentricity and mutual inclination in multiple stellar systems at birth.
Characterising the intra-cluster light in The Three Hundred simulations
Authors: Contreras-Santos A. , Knebe A. , Cui W. , Alonso Asensio I. , Dalla Vecchia C. , Cañas R. , Haggar R. , Mostoghiu Paun R. A. , Pearce F. R. , Rasia E.
Published: December 2023

We characterise the intra-cluster light (ICL) in ensembles of full-physics cluster simulations from THE THREE HUNDRED project, a suite of 324 hydrodynamical resimulations of cluster-sized halos. We identify the ICL as those stellar particles bound to the potential of the cluster itself, but not to any of its substructures, and separate the brightest cluster galaxy (BCG) by means of a fixed 50 kpc aperture. We find the total BCG+ICL mass to be in agreement with state-of-the-art observations of galaxy clusters. The ICL mass fraction of our clusters is between 30 and 50% of the total stellar mass within R500, while the BCG represents around 10%. We further find no trend of the ICL fraction with cluster halo mass, at least not in the range [0.2, 3] 1015 h−1 M⊙ considered here. For the dynamical state, characterised both by theoretical estimators and by the recent merging history of the cluster, there is a clear correlation, such that more relaxed clusters and those that have undergone fewer recent mergers have a higher ICL fraction. Finally, we investigate the possibility of using the ICL to explore the dark matter (DM) component of galaxy clusters. We compute the volumetric density profile for the DM and ICL components and show that, up to R500, the ratio between the two can be described by a power law. Working with the velocity dispersion profiles instead, we show that the ratio can be fit by a straight line. Providing the parameters of these fits, we show how the ICL can be used to infer DM properties.
Tax Relations: Current Thinking and New Realities
Authors: Ahrorov Zarif , Sharin Oleksandr , Tuychiev Sherkhon , Khudaybergenov Abidjon , Yunusova Sevara , Raimjanova Madina , Shaislamova Nargiza
Published: December 2023

Considering taxes to be the universally recognized regulator of the economy, related ideas on the proper organization of tax relations are being promoted in various scientific papers. The relevance of this problem is caused, firstly, by the choice of a model of tax regulation within the framework of the general economic situation, by thoughts that are about “tax relations”, “principles of taxation”, “mechanism taxation”, “about the nature of the tax”, and secondly the within the framework of the tax system operating in the Republic of Uzbekistan, the instruments of tax relations are characterized by high economic inefficiency. The purpose of this research is to generalize the works on tax relations, improve tax regulation, develop the necessary proposals and recommendations to enhance the role of tax regulation mechanisms in the framework of improving tax policy that aimed at ensuring high economic growth. The paper also analyzes theories of tax regulation in the framework of using tax regulation mechanisms in order to ensure the growth of income (profit) of economic entities with a simultaneous decrease in the share of tax revenues in GDP. By defining the economic boundaries of tax policy, it is possible to solve not only the problems of economic growth of the country as whole, but also social issues in changing economic conditions. The paper also analyzes the opinions of various domestic and foreign economists on tax relations.
Investigations on photovoltaic material absorptivity using hyperspectral photoluminescence excitation imaging
Authors: Legrand Marie , Bérenguier Baptiste , Campos Thomas , Ory Daniel , Guillemoles Jean-François
Published: December 2023

Photoluminescence imaging has become a standard method to characterize solar cells. However, performing some quantitative analysis of this technique requires the assumption of uniform local absorptivity, which cannot be directly measured using traditional methods. This study presents a novel approach to measure the local relative absorptivity over a broad spectral range for a perovskite absorber deposited on a charge extraction layer and an electrode. By analyzing the photoluminescence intensity as a function of the incident photon energy, we were able to determine the relative absorptivity of the incident light above the bandgap energy. Additionally, luminescence spectra allow us to accurately assess the absorptivity near the bandgap energy from the reciprocity between absorption and emission. Reflectivity measurements were also performed to further understand the possible limitations of our experiment and to discuss our results. Finally, this method was able to distinguish between variations in the photoluminescence response caused by slight differences in the local film thickness and changes in the local carrier lifetime.
Die sechs häufigsten peripheren vestibulären Syndrome
Authors: Strupp Michael Leo , Zwergal Andreas , Goldschagg Nicolina
Published: December 2023

Periphere vestibuläre Syndrome beruhen auf einer Funktionsstörung des Labyrinths und/oder des Nervus vestibulocochlearis. Phänomenologisch und pathophysiologisch lassen sich 3 Formen klinisch unterscheiden: 1. Rezidivierende Schwindelepisoden mit je nach Ursache unterschiedlicher Dauer, unterschiedlichen Begleitsymptomen und Auslösern. Die zugrunde liegenden Erkrankungen sind der Benigne periphere paroxysmale Lagerungsschwindel, Morbus Menière, Vestibularisparoxysmie und das Syndrom der dritten mobilen Fenster. 2. Das akute vestibuläre Syndrom, bedingt durch eine akute vestibuläre Tonusdifferenz mit dem Leitsymptom heftiger langdauernder Drehschwindel: die akute unilaterale Vestibulopathie/Neuritis vestibularis. 3. Persistierender Schwankschwindel und Gangunsicherheit bedingt durch ein bilaterales vestibuläres Defizit: die bilaterale Vestibulopathie. Für alle diese Erkrankungen liegen Diagnosekriterien der Bárány-Society vor, die gleichermaßen wichtig sind für die klinische Praxis und für wissenschaftliche Studien. Für die Behandlung peripherer vestibulärer Syndrome werden in Abhängigkeit von der Ursache 5 Therapieprinzipien eingesetzt: 1. Sorgfältige Aufklärung des Patienten über Art und Ursache der Beschwerden und die Therapieeffekte; dies ist auch wichtig für die Compliance des Patienten. 2. Physikalisch-medizinische Behandlung: A) Bogengangspezifische Befreiungsmanöver: für den posterioren Kanal das SémontPlus-Manöver, das dem Sémont- und Epley-Manöver überlegen ist; für den horizontalen Kanal das modifizierte Roll-Manöver und für den anterioren Bogengang das modifizierte Yacovino-Manöver. B) Balancetraining bei sensorischen Defiziten (hohe Evidenz). 3. Symptomatische oder kausale medikamentöse Behandlung. Hier mangelt es weiterhin an placebokontrollierten Pharmakotherapiestudien, sodass die Evidenzlage niedrig ist und ein hoher klinischer Forschungsbedarf besteht. 4. Operative Maßnahmen, z. B. bei dem Syndrom der dritten mobilen Fenster. 5. Bei funktionellem Schwindel psychotherapeutische Verfahren.
Aufsuchende Wochenbettbetreuung: Die sozioökonomische Lage
hat einen starken Einfluss auf den Betreuungsumfang Eine Analyse mit
Routinedaten der BARMER
Authors: Hertle Dagmar , Wende Danny , zu Sayn-Wittgenstein Friederike
Published: December 2023

Hintergrund Die sozioökonomische Lage ist mit Ungleichheit im
Zugang zur Gesundheitsversorgung und zu gesundheitsrelevanten Ressourcen
verbunden. Dies trifft auch auf Schwangerschaft, Geburt und Wochenbett zu.
Deutschland verfügt über eine im europäischen Vergleich
einzigartige aufsuchende Wochenbettbetreuung über 12 Wochen nach der
Geburt und in Problemfällen darüber hinaus und bietet damit
strukturell gute Versorgungsmöglichkeiten. Bisher gibt es jedoch kaum
Studien auf der Basis von Routinedaten, die zeigen, welche Wöchnerinnen
in welchem Umfang die aufsuchende Wochenbettbetreuung erhalten.

Methode Die Studienpopulation umfasste 199.978 bei der BARMER versicherte
Frauen, die in den Jahren 2017–2020 mindestens ein Kind geboren haben.
Manche Frauen waren im Betrachtungszeitraum mehrmals schwanger. Betrachtet
wurden die von freiberuflichen Hebammen abgerechneten Leistungen der
aufsuchenden Hebammenbetreuung im Wochenbett bei 227.088 Geburten unter Einbezug
der sozioökonomischen Lage der Mütter.

Ergebnisse 26% der Mütter gehörten nach der
Definition des Deutschen Instituts für Wirtschaftsforschung in eine
niedrige, 46% mittlere und 29% in eine hohe Einkommensgruppe.
Ähnlich wie für die Hebammenversorgung in der Schwangerschaft
gezeigt, fanden sich auch hinsichtlich der aufsuchenden Wochenbettbetreuung
große Unterschiede: Während 90,5% der Frauen mit hohem
Einkommen aufsuchende Wochenbettbetreuung erhielten, waren es bei den Frauen mit
mittlerem Einkommen nur 83,5% und bei den Frauen mit niedrigem Einkommen
sogar nur 67,9%. Die Gruppen unterschieden sich hinsichtlich weiterer
Merkmale wie Kaiserschnittrate, Frühgeburten,
Mehrlingsschwangerschaften, Begleiterkrankungen oder Alter nicht in einem
Ausmaß, das den Unterschied in der Versorgung erklären
könnte. Frauen, die in der Schwangerschaft bereits abgerechnete
Hebammenleistungen erhalten hatten, erhielten sehr viel häufiger im
Wochenbett Hausbesuche durch die Hebamme. Darüber hinaus fand sich ein
Zusammenhang zur Hebammendichte in der jeweiligen Region.

Schlussfolgerungen Die Ergebnisse legen nahe, dass der Zugang zur
häuslichen Wochenbettbetreuung durch freiberufliche Hebammen für
Frauen mit niedrigem Einkommen deutlich eingeschränkt ist. Im Gegensatz
zur Schwangerenvorsorge können Frauen im Wochenbett nicht auf andere
Leistungserbringer*innen ausweichen, da aufsuchende Wochenbettbetreuung
eine Vorbehaltstätigkeit von Hebammen ist. Frauen mit niedrigem
Einkommen erhalten somit weniger Hebammenbetreuung, obwohl von einem
höheren Unterstützungsbedarf ausgegangen werden kann (Eickhorst
et al. 2016).
Schnittstellenkommunikation und Informationstransfer in der
medizinischen Versorgung von Menschen mit intellektueller
Entwicklungsstörung: Qualitative
Expert*innen-Interviews
Authors: Mainz Anne , Meister Sven , Budroni Helmut , Hasseler Martina , Schmidt Peter , Stockmann Jörg , Schulte Andreas G. , Kersting Christine , Mortsiefer Achim , Schmidt Alexandra
Published: December 2023

Ziel der Studie In Deutschland leben etwa 350.000 Menschen mit
Störungen der geistigen bzw. intellektuellen Entwicklung. Sie sind bei
Kommunikation mit den Leistungserbringenden des Gesundheitswesens auf
Unterstützung angewiesen. Ein unzureichender Informationstransfer kann
dabei folgenschwer sein. Diese Studie untersucht Erfahrungen, Barrieren und
Lösungsansätze in der Kommunikation bei der Versorgung von
Menschen mit intellektueller Entwicklungsstörung. Die Potentiale des
Einsatzes digitaler Anwendungen zum Informationstransfer sollen eine besondere
Betrachtung finden.

Methodik Es wurden 13 leitfadengestützte
Expert*innen-Interviews mit Betreuenden und medizinisch Versorgenden von
Menschen mit intellektueller Entwicklungsstörung geführt. Es
wurde eine inhaltlich strukturierende Inhaltsanalyse mit deduktiv-induktiver
Kategorienbildung nach Meuser und Nagel durchgeführt.

Ergebnisse Die Versorgung von Menschen mit intellektueller
Entwicklungsstörung ist geprägt von Zeitmangel und Unsicherheit
im Umgang, wenn Erfahrungen im Umgang fehlen. Der Informationstransfer ist
geprägt von einer Informationsflut von sehr individuellen Informationen,
die mündlich oder schriftlich durch Betreuende weitergegeben werden,
sowie von einer passiven Rolle der Patient*innen häufig ohne
gezielte Einbindung in die Kommunikation. Hinsichtlich der Potentiale zur
Einbindung digitaler Anwendungen zum Informationstransfer zeigt sich eine
Kontroverse zwischen Chance und Risiko.

Schlussfolgerung Fortbildung im Umgang mit Menschen mit intellektueller
Entwicklungsstörungen sowie ausreichende Zeitkontingente sind zentrale
Faktoren für erfolgreiche Schnittstellenkommunikation. Externe Arbeiten
zeigen, dass Informationstransfer durch digitale Anwendungen unterstützt
werden kann, wenn handhabbare und implementierbare technische Ausstattung
bereitsteht. Digitale Anwendungen bieten dabei neue Möglichkeiten, mit
Menschen mit intellektueller Entwicklungsstörung zu kommunizieren, wie
durch die Nutzung von Formaten mit leichter oder bildlicher Sprache. Hierzu
bedarf es jedoch anknüpfenden Forschung, welche sich mit der digitalen
Kontroverse in dieser Arbeit auseinandersetzt.
Betäubungsmittelkonsum unter Bewährungs- und
Führungsaufsicht – Eine Langzeituntersuchung zum
risikogruppenspezifischen Rückfallgeschehen unter
Abstinenzauflagen
Authors: Kappl Ursula , Huppertz Bernd , Stöver Heino , Stich Heribert
Published: December 2023

Zielsetzung der Studie Zielsetzung dieser Langzeituntersuchung war die
Erfassung substanzspezifischer Prävalenzen widerrechtlichen Konsums von
Betäubungsmittel (BTM) trotz gerichtlicher Abstinenzauflagen.

Methodik Auf der Grundlage der Amtshilfe für die
Bewährungshilfe eines Landgerichtes wurden durch ein Gesundheitsamt
Urinasservate gewonnen. Die individuelle und valide Zuordnung dieser Urinproben
wurde durch Anwendung eines bewährten Marker-Systems
gewährleistet. Nach postalischem Versand erfolgten in einem externen
Labor die laborchemischen Analysen auf BTM-Rückstände mittels
Enzymimmunoassay und Validierung durch Massenspektrographie im Falle positiver
BTM-Nachweise. Auf der Basis aller vorliegenden Routinedaten konnte ein
gepoolter Datensatz über insgesamt vierzehn konsekutiver Kalenderjahre
(2006–2019) digital generiert und anonymisiert ausgewertet werden.

Ergebnisse Von insgesamt 380 Betroffenen (weiblich: 13% versus
männlich: 87%; Durchschnittsalter: 30,4 Jahre) lagen 13.500
BTM-Einzelanalysen aus 2.941 Urinproben vor. Dabei waren in 2,7% aller
Einzelanalysen mindestens eines von acht potentiellen BTMs nachzuweisen, wobei
sich für Cannabis mit 3,7% und für Opiate mit
2,4% die weitaus höchsten Gesamtprävalenzen im Sinne
eines Rückfalles feststellen ließen. Hingegen waren fast keine
Rückstände für Barbiturate und LSD beziehungsweise
keinerlei positive Nachweise für Buprenorphine und PCP zu
führen. Erwartungsgemäß waren die meisten
Rückfälle in allen BTM-Gruppen in den Altersgruppen von 18 bis
35 Jahren vorzufinden. Auffallenderweise verstießen mehr Frauen als
Männer mit Amphetaminen gegen die gerichtliche Abstinenzauflage,
während sich die Rückfälle mit den anderen sieben
BTM-Gruppen vorwiegend bei Männern ereigneten. Im Verlauf des gesamten
Beobachtungszeitraumes waren für Cannabis, Opiaten und Cocain die
deutlichsten Schwankungen bei den Rückfallhäufigkeiten
vorzufinden.

Schlussfolgerung BTM-Konsum während der Bewährungs- und
Führungsaufsicht scheint eher kein seltenes Ereignis zu sein und fand
bisher wenig fachliche Beachtung. Durch ein vermehrtes Augenmerk auf dieses
gruppenspezifische Rückfallgeschehen und durch mehr themenbezogene
Studien sollte dieses Defizit gemindert werden.
15.9.5 Acridines (Update 2024)
Authors: Wang L. , Liu M. , Cheng J.
Published: December 2023

Acridine derivatives form a class of nitrogen-containing compounds with a broad spectrum of biological activity, including against cancer, bacteria, parasites, HIV, fungi, and Alzheimer’s disease. This is an update to the previous Science of Synthesis contribution covering methods for the preparation of acridines, focusing on advances reported between 2005 and 2022.
22.1.3.3 Thiocarboxylic O-Acid Esters (Update 2024)
Authors: Li X. , Song Q.
Published: December 2023

Sulfur-containing functional groups feature widely in a broad spectrum of important compounds, including natural products, pharmaceuticals, and materials. Methods for the synthesis of thiocarboxylic O-acid esters have been well-summarized and reviewed in Science of Synthesis in 2005; this update is focused on the most significant advances that have been reported since then.
22.1.4.3 Dithiocarboxylic Acid Esters (Update 2024)
Authors: Li X. , Song Q.
Published: December 2023

Sulfur-containing functional groups feature widely in a broad spectrum of important compounds, including natural products, pharmaceuticals, and materials. Methods for the synthesis of dithiocarboxylic acid esters have been well-summarized and reviewed in Science of Synthesis in 2005; this update is focused on the most significant advances that have been reported since then.
Critical Evaluation of the Thermodynamic Properties of Na2Cr2O7, K2Cr2O7, Na2Mo2O7, K2Mo2O7, Na2W2O7, and K2W2O7
Authors: Benalia Sara , Chartrand Patrice , Robelin Christian
Published: December 2023

This study outlines an extensive investigation of crystallographic data and thermodynamic properties (including solid-solid transition and fusion) for sodium dichromate, potassium dichromate, sodium dimolybdate, potassium dimolybdate, sodium ditungstate, and potassium ditungstate. A thorough literature review was conducted to obtain a good understanding of the data available in the literature, and a critical and complete evaluation has been performed from room temperature to above the melting temperatures. This work is one of the key steps towards the development of a thermodynamic model for the Na+, K+//Cl−, SO42−, CO32−, CrO42−, Cr2O72−, MoO42−, Mo2O72−, WO42−, W2O72−, O2− system, relevant for high temperature corrosion in atmospheres containing O–H–S–C–Cl and alkali salts.
Excited-state normal-mode analysis: The case of porphyrins
Authors: Rukin Pavel , Prezzi Deborah , Rozzi Carlo Andrea
Published: December 2023

We systematically applied excited-state normal mode analysis to investigate and compare the relaxation and internal conversion dynamics of a free-base porphyrin (BP) with those of a novel functional porphyrin (FP) derivative. We discuss the strengths and limitations of this method and employ it to predict very different dynamical behaviors of the two compounds and to clarify the role of high reorganization energy modes in driving the system toward critical regions of the potential energy landscape. We identify the modes of vibrations along which the energy gap between two excited-state potential energy surfaces within the Q band manifold may vanish and find that the excess energy to reach this “touching” region is significantly reduced in the case of FP (0.16 eV) as compared to the one calculated for BP (0.92 eV). Our findings establish a link between the chemical functionalization and the electronic and vibrational structure that can be exploited to control the internal conversion pathways in a systematic way.
Enhancing Monte Carlo simulations of aerosol scattering using photon matrices
Authors: Pang Zhihua , Song Chengtian , Liu Bohu
Published: December 2023

Within aerosol-rich environments, efficient simulation of frequency-modulated continuous wave (FMCW) laser detector echo characteristics is crucial. Conventional methods often need more efficiency. To address this, we propose a photon matrix-based approach for simulating intricate photon scattering processes, enhancing simulation accuracy. This study focuses on short-range FMCW laser detection under aerosol interference, assessing performance via signal-to-noise ratio (SNR). We analyze the impact of amplitude modulation coefficient and photon count on SNR. Surprisingly, the photon count minimally affects SNR, while the amplitude modulation coefficient significantly influences it. These findings shed light on optimizing FMCW laser detection in aerosol-laden environments. Attention to the amplitude modulation coefficient can notably enhance SNR and overall detection efficiency.
Development of a subgrid-scale model for Burgers turbulence using statistical mechanics-based methods
Authors: Ross Molly , Bindra Hitesh
Published: December 2023

Turbulent flows can be simulated using direct numerical simulations (DNS), but DNS is computationally expensive. Reduced-order models implemented into Reynolds-averaged Navier–Stokes and large eddy simulations (LES) can reduce the computational cost, but need to account for subgrid-scale (SGS) turbulence through closure relations. Turbulence modeling has presented a significant challenge due to the non-linearities in the flow and multi-scale behavior. Well-established features of the turbulent energy cascade can be leveraged through statistical mechanics to provide a characterization of turbulence. This paper presents a physics-based data-driven SGS model for LES using the concepts of statistical mechanics. The SGS model is implemented and tested using the stochastic Burgers equation. DNS data are used to calculate Kramers–Moyal (KM) coefficients, which are then implemented as an SGS closure model. The presented data-driven KM method outperforms traditional methods in capturing the multi-scale behavior of Burgers turbulence.
Characterizing jamming of dilute and semi-dilute fiber suspensions in a sudden contraction and a T-junction
Authors: Villalba Miguel E. , Daneshi Masoud , Martinez D. Mark
Published: December 2023

The clogging or jamming of particle suspensions is a ubiquitous problem, hindering the efficiency of particle–liquid and particle–particle separations. Motivated by pressure screening in the pulp and paper industry, we characterize jamming of dilute and semi-dilute mono-disperse rigid-rod suspensions passing through channels mimicking dead-end and cross-flow filtration membranes, experimentally, using particle-tracking velocimetry. We observe that jams nucleate by either bridging of isolated particles across the constriction, or by localized mechanical entanglement of the particles, i.e., flocculation. Uniquely, we observe floc-formation during acceleration into the aperture and report this as primary mechanism for jamming events. We characterized the accumulation-release cycles of the jamming event using an exponential probability distribution; this distribution is indicative of a Poisson process. For jams nucleated by single-particle bridging, the distribution is (primarily) related to the number of fibers passing through the aperture; this is similar to dry, granular materials. For floc-based nucleation events, the distribution is (primarily) related to the suspension concentration with the average time between jams decreasing inversely with the square-root of the initial suspension concentration. For the conditions tested, the distribution was insensitive to changes in constriction geometry.
Anomalous segmental dynamics of supercooled polyrotaxane melts: A computer simulation study
Authors: Jia Xiang-Meng , Zhou Jiajia
Published: December 2023

Polyrotaxanes, which consist of mechanically interlocked bonds with rings threaded onto soft polymer chains, exhibit unique mechanical properties and find applications in diverse fields. In this study, we investigate the anomalous segmental dynamics of supercooled polyrotaxane melts using coarse-grained molecular dynamics simulations. Our simulations reveal that the presence of rings effectively reduces the packing efficiency, resulting in well-contained local motion even below the glass transition temperature. We also observe variations in dynamical free volume, characterized by the Debye–Waller factor, which shows a minimum at a ring coverage of 0.1 on threading chains. Such a non-monotonic dependence on coverage shows great consistency in structural relaxation time and dynamic heterogeneity. Specifically, the high segmental mobility of threading linear chains at large coverage can be attributed to the increased dynamical free volume due to supported rigid rings. However, such anomalous segmental dynamics is limited to length scales smaller than one ring size. Beyond this characteristic length scale, the diffusion is dominated by topological constraints, which significantly reduce the mobility of polyrotaxanes and enhance the dynamic heterogeneity. These findings offer microscopic insights into the unique packing structures and anomalous segmental dynamics of supercooled polyrotaxane melts, facilitating the design of advanced materials based on mechanical interlocking polymers for various applications.
Fingerprints of hydrogen bonding in the terahertz dynamics of ethanol and water: An inelastic x-ray scattering study
Authors: De Francesco A. , Formisano F. , Scaccia L. , Guarini E. , Bafile U. , González M. A. , Alatas A. , Lynch S. T. , Cunsolo A.
Published: December 2023

We used inelastic x-ray scattering methods to measure the terahertz spectrum of density fluctuations of ethanol in both liquid and solid phases. The results of a Bayesian inference-based lineshape analysis with a multiple excitation model and the comparison with a previous similar analysis on water indicate that the different structures induced by hydrogen bonds in ethanol and water have a profound influence on the respective dynamic responses, the latter being characterized by longer living and better resolved high-frequency acoustic excitations. In addition, we compare these findings with those obtained with an alternative approach based on the exponential expansion theory and ensuring sum rules fulfillment, demonstrating that the model’s choice directly impacts the number of spectral modes detected.
Tackling African swine fever in India
Authors: Parthiban S. , Raja P. , Parthiban M. , Yamini C.
Published: December 2023

Globally, African swine fever (ASF) is the most feared swine viral disease, associated with a mortality rate of up to 100%. More than half of the world’s swine population is located in Asia. ASF outbreaks in Asia have a significant impact on the global pig industry. Pig industry’s economic losses have been huge because of ASF outbreaks. Swine husbandry in India is in a flourishing phase to meet food security demands, but the losses associated with ASF greatly hamper its expansion. ASF in India can be controlled and eradicated through strict biosecurity measures and vaccination. Development of penside point-of-care (POC) rapid diagnostics and effective indigenous vaccines are prerequisites to tackle ASF in India. Sensitization of veterinary professionals, researchers, and pig farmers about disease pathogenesis, transmission, and impact are crucial part of ASF control. This review presents the status of ASF in India in comparison to other parts of the world, and current approaches in India to deal with ASF. Further roadmap to combat this calamitous swine infection in India.
Observation of the dynamic evolution process of vacuum arc microscopic particles based on the emission spectrum principle
Authors: Liu Shan , Yuan Zhao , Zhang Jin , Liu Liming , Chen Lixue , Wu Chuanqi , Pan Yuan
Published: December 2023

The distribution of microscopic particles directly affects the recovery of the post arc insulating medium and determines whether the fault current can be interrupted. Based on the principle of vacuum arc emission spectrum, a high-speed spectrum observation platform was built to study the distribution of microscopic particles during the arc burning, and the axial and radial spectral line intensity and density distributions of atoms and ions under different current amplitudes were obtained. The results show that the CuI spectral line intensity has two peaks near the cathode and anode, while in the arc column it is relatively low. The peak of the CuI spectral line intensity near the electrode is caused by electrode evaporation. The peak duration of the CuI spectral line intensity near the cathode is always longer than that near the anode. The CuII spectral line intensity is lower, appears later and disappears earlier, which in the arc column increased obviously, compared with CuI. The CuII density near the cathode is higher than that near the anode, and the CuII density in the arc column is higher than in the two electrodes, which is similar to the axial distribution of electron density. The radial distribution curve of CuI and CuII density is similar to the radial distribution curve of spectral line intensity, and displays the characteristics of a high center and low edge in the radial direction of the arc gap. The difference is that the width of the atomic spectral line is larger than that of the corresponding ionic spectral line, the distribution curve of the ionic spectral line is smooth and symmetrical, and the radial attenuation rate of the CuII density is larger than that of the corresponding CuI. This reflects the ionization of atoms and the effect of magnetic fields. The radial and axial distribution of the particle density is opposite to that of the excitation temperature. Electrode emission will first affect the atom formation.
Enhanced electrocatalytic degradation of tetracycline by ZIF-67@CNT coupled with a self-standing aligned carbon nanofiber anodic membrane
Authors: Yu Shuyan , Zhang Huiying , Zhou Yan , Li Congju
Published: December 2023

Due to the misuse and overuse of the antibiotic tetracycline (TC), as well as its refractory degradability, it has become a stubborn environmental contaminant. In this study, a self-standing polyacrylonitrile-based ZIF-67@CNT/ACF aligned anodic membrane was fabricated by innovatively incorporating ZIF-67@CNT nanoparticles into an aligned carbon nanofiber (ACF) membrane to treat the TC. The flow-through nanoporous construction of the ZIF-67@CNT/ACF membrane reactor can compress the diffusion boundary layer on the electrode surface to enhance mass transfer under microscopic laminar flow, which can further enhance the degradation rate. In addition, the enhanced degradation performance also benefited from the significant electrooxidation capacity of the ZIF-67@CNT/ACF membrane. At the optimal electrocatalytic condition of 3.0 V applied potential and pH 6, the degradation rate reached 81% in 1 h for an initial TC concentration of 10 mg l−1. The refractory and highly toxic TC was electrochemically degraded into small non-toxic molecules. Our results indicate that electrocatalytic TC degradation can be enhanced by ZIF-67@CNT/ACF membrane.
Reduced graphene oxide/SiC nanowire composite aerogel prepared by a hydrothermal method with excellent thermal insulation performance and electromagnetic wave absorption performance
Authors: Wang Zhijian , Li Rong , Liu He , Liu Xingmin , Zheng Feng , Yu Chen
Published: December 2023

In aerospace and downhole exploration, materials must function reliably in challenging environments characterized by high temperatures and complex electromagnetic (EM) interference. Graphene oxide (GO) aerogels are promising materials for thermal insulation, and the incorporation of silicon carbide nanowires can enhance their mechanical properties, thermal stability and EM absorption efficiency. In this context, citric acid acts as both a cross-linking and reducing agent, facilitating the formation of a composite aerogel comprising GO and SiC nanowires (rGO/m-SiC NWs). Compared with GO aerogels, the representative composite aerogel sample rGS4 demonstrated significantly improved mechanical properties (yield strength increased by 0.031 MPa), outstanding thermal stability (ability to withstand temperatures up to 800 °C) and remarkably low thermal conductivity (measuring just 0.061 W m–1 K–1). Importantly, the composite aerogels displayed impressive EM absorption characteristics, including a slim profile (2.5 mm), high absorption capacity (−42.23 dB) and an exceptionally broad effective absorption bandwidth (7.47 GHz). Notably, the specific effective absorption bandwidth of composite aerogels exceeded that of similar composite materials. In conclusion, rGO/m-SiC NWs exhibited exceptional mechanical properties, remarkable thermal stability, efficient thermal insulation and outstanding microwave absorption capabilities. These findings highlight their potential for use in high-temperature and electromagnetically challenging environments.
Subthreshold slope below 60 mV/decade in graphene transistors induced by channel geometry at the wafer-scale
Authors: Dragoman Mircea , Dinescu Adrian , Vulpe Silviu , Dragoman Daniela
Published: December 2023

In this paper, we demonstrate experimentally that field-effect transistors with nanoconstricted graphene monolayer channels have a subthreshold swing (SS) below 60 mV/dec, which is slightly dependent on temperature. Two shapes of nanoconstricted graphene monolayers are considered: (i) a bow-tie shape, representative for a symmetric channel, and (ii) a trapezoidal shape, which illustrates an asymmetric channel. While both types of nonuniform channels are opening a bandgap in graphene, thus showing an on/off ratio of 105, the SS in the graphene bow-tie channel is below 60 mV/dec in the temperature range 25 °C–44 °C.
Atomistic modeling of electromechanical properties of piezoelectric zinc oxide nanowires
Authors: Meguid S A , Kundalwal S I , Alian Ahmed R
Published: December 2023

Currently, numerous articles are devoted to examining the influence of geometry and charge distribution on the mechanical properties and structural stability of piezoelectric nanowires (NWs). The varied modeling techniques adopted in earlier molecular dynamics (MD) works dictated the outcome of the different efforts. In this article, comprehensive MD studies are conducted to determine the influence of varied interatomic potentials (partially charged rigid ion model, [PCRIM] ReaxFF, charged optimized many-body [COMB], and Buckingham), geometrical parameters (cross-section geometry, wire diameter, and length), and charge distribution (uniform full charges versus partially charged surface atoms) on the resulting mechanical properties and structural stability of zinc oxide (ZnO) NWs. Our optimized parameters for the Buckingham interatomic potential are in good agreement with the existing experimental results. Furthermore, we found that the incorrect selection of interatomic potentials could lead to excessive overestimate (61%) of the elastic modulus of the NW. While NW length was found to dictate the strain distribution along the wire, impacting its predicted properties, the cross-section shape did not play a major role. Assigning uniform charges for both the core and surface atoms of ZnO NWs leads to a drastic decrease in fracture properties.
Universal Casimir attraction between filaments at the cell scale
Authors: Spreng Benjamin , Berthoumieux Hélène , Lambrecht Astrid , Bitbol Anne-Florence , Maia Neto Paulo , Reynaud Serge
Published: December 2023

The electromagnetic Casimir interaction between dielectric objects immersed in salted water includes a universal contribution that is not screened by the solvent and therefore long-ranged. Here, we study the geometry of two parallel dielectric cylinders. We derive the Casimir free energy by using the scattering method. We show that its magnitude largely exceeds the thermal energy scale for a large parameter range. This includes length scales relevant for actin filaments and microtubules in cells. We show that the Casimir free energy is a universal function of the geometry, independent of the dielectric response functions of the cylinders, at all distances of biological interest. While multiple interactions exist between filaments in cells, this universal attractive interaction should have an important role in the cohesion of bundles of parallel filaments.
Polarization of electromagnetic pulses
Authors: Lekner John
Published: December 2023

We show the impossibility, for localized and exact solutions of the Maxwell equations, of perfect circular polarization in a fixed plane, or perfect linear polarization along a fixed direction. A measure of polarization of electromagnetic pulses is obtained by analogy with that useful in monochromatic radiation, and its limitations discussed. Using oscillatory solutions of the free-space Maxwell equations, for which all components of the electric and magnetic fields satisfy the wave equation, we construct explicit examples of TE pulses which are linearly polarized with an azimuthal electric field, TE+iTM pulses approximately linearly polarized along the propagation direction, and also approximately circularly polarized pulses. The latter have perfect circular polarization on the propagation axis.
Emerging II-VI wide bandgap semiconductor device technologies
Authors: Kuddus Abdul , Mostaque Shaikh Khaled , Mouri Shinichiro , Hossain Jaker
Published: December 2023

The demand for advanced electronic and optoelectronic devices has driven significant research and development efforts toward exploring emerging semiconductor materials with enhanced performance characteristics. II-VI semiconductors have been studied extensively owing to their wide bandgap characteristics, which enable high electron mobility, excellent thermal stability, and resistance to radiation damage. These properties make them well-suited for a range of applications, including solar cells, light-emitting diodes (LEDs), photodetectors, lasers, sensors, and field effect transistors (FETs). In II-VI compounds, both ionic and covalent bonds exist with a higher electronegative nature of the VI-group elements than II-group elements. This existing ionic behavior strongly influences the binding of valence band electrons rather strongly to the lattice atoms. Thus, the II-VI semiconductors such as CdS, CdTe, ZnS, ZnSe, and CdSe possess wide tunable bandgaps (~0.02 to ≥ 4.0 eV) and high absorption coefficients of approximately 106 cm−1, setting them apart from other semiconductors formed by a covalent bond with closely equal atomic weights. This review article delves into the physics of II-VI semiconductor homo/heterojunctions, and the steps involved in device fabrication including lithography, etching, metallization, stability (oxidation and passivation) and polymerization together with several doping strategies. Furthermore, this review explores the process for tuning the distinct physical and chemical properties and a substantial advancement in electronic, and optoelectronic devices, including tools, cutting-edge equipment, and instrumentations. This comprehensive review provides detailed insights into the potential and technological progress of II-VI wide bandgap semiconductor device technology including experienced challenges and prospects.