bluuebunny/crossref_metadata_2025 huggingface dataset:
Investigating the processes and rate of iodide ion and compound oxidation in subterranean hydrothermal waters
Authors: Ibragim Umbarov , Turayev Khaid , Uralov Nuriddin , Abduraxmonov Sayyod , Musayev Chori , Tursunov Khurshid , Eshonqulov Khasan , Kadirova Nargiza
Published: April 2024

Studies using physico-chemical methods have been conducted to evaluate the oxidative characteristics of various reagents for the technological extraction of iodine from groundwater and sufficient data have been obtained. According to the research results, iodine is predominantly present in the form of molecular iodine (85.6%), iodide ions (3.2%), iodate (9.1%) and iodine chloride (2.1%) were detected. Preserving all forms of iodine in solution at the same time is possible only in an alkaline environment, where the oxidizing properties of iodates are sharply reduced. This information is important for choosing a method for purifying iodine paste using various physical and chemical methods. From experiments in research, the beginning of the release of elemental iodine was noted at a voltage above 0.250 V and a pH of 5-3 or less. In this case, the solution usually becomes dark red with a reddish or brownish tint, which indicates the formation of complex compounds of iodine with other ions in the solution.
Taxonomic diversity of archegonial plants of Central Siberia
Authors: Antipova Ekaterina , Pasko Olga
Published: April 2024

The impact of human activities on natural processes highlights the changing landscape and vegetation cover. This study aimed to assess the taxonomic diversity of higher spore-bearing archegonial plants in the Emelyanovsky region, part of the Krasnoyarsk urban agglomeration, covering an area of 7.4 thousand square kilometers. Previous floristic studies in the region were limited, with flora documentation incidental to other research. Fieldwork utilized specific floras and route surveys, identifying eight distinct local floras based on phytocenotic and landscape diversity, and anthropogenic influences. A total of 940 plant species from 340 genera and 89 families were documented in the region. Among archegonial plants, polypodiophytes were the most prevalent (1.28% of all species), while gnetophytes were the least represented (0.11%) in the studied area’s flora structure.
Development of a precision farming system based on the use of UAVs for spraying pesticides and fertilizers
Authors: Kovalev Igor , Kovalev Dmitry , Podoplelova Valeria , Borovinsky Dmitry
Published: April 2024

Further effective development of the precision farming system is largely associated with the use of UAVs for spraying pesticides and fertilizers. The article analyzes the characteristics of UAVs for spraying pesticides and fertilizers (spraying drones) and notes the advantages of UAVs for aerial spraying, as well as the problems that hinder their use. Previously published work discusses the use of agricultural UAVs to spray liquid pesticides, but it should be noted that dry crop protection products, including biological pesticides and dry fertilizers, can also be used. Conditions are given that require the expanded use of UAVs for spraying pesticides and fertilizers as part of the further development of a precision farming system. These conditions confirm that the development of a UAV-based precision agriculture system for spraying fertilizers and pesticides for plant protection is currently a viable option when choosing unmanned aerial equipment. The swarm (or group) use of agricultural UAVs is promising. In this case, research into the microprocessor performance of drone swarms is of particular importance to improve the safety of UAV transport and technological cycles, which combine ground and airborne operations performed by both the operator and the components of the unmanned aircraft system.
Entwicklung eines beispielhaften kompetenzorientierten Blended-Learning-Konzeptes für die Physiotherapie-Ausbildung
Authors: Cordes Ann Katrin
Published: April 2024

Hintergrund Zukünftige Physiotherapeut*innen müssen gleichermaßen auf fachliche und fachübergreifende Herausforderungen in einer digitalen Lebens- und Arbeitswelt vorbereitet werden. Gefördert werden sollte neben der Entwicklung von Fachkompetenz auch die Entwicklung von personalen Kompetenzen sowie digitaler Medienkompetenz.

Ziel Entwicklung eines beispielhaften kompetenzorientierten Blended-Learning-Konzeptes für die Physiotherapie-Ausbildung.

Methoden 1) Systematische Literaturrecherche, 2) Online-Umfrage unter Lernenden und Lehrenden einer Berufsfachschule für Physiotherapie, 3) Entwicklung eines beispielhaften kompetenzorientierten Blended-Learning-Konzeptes und 4) Validierung des entwickelten Konzeptes im Rahmen eines Expert*innen-Workshops.

Ergebnisse 1) International wird zur Förderung von Kompetenzentwicklung Problemorientiertes Lernen (POL) in der Physiotherapie-Ausbildung eingesetzt, wobei die Umsetzung teils erheblich variiert. Hinsichtlich Blended Learning gibt es keine eindeutigen Ergebnisse, die auf besonders geeignete Tools hinweisen. Entscheidend ist für den Einsatz beider Konzepte die Berücksichtigung der Voraussetzungen der Lernenden und Lehrenden bei sämtlichen Überlegungen und Entscheidungen. Die Auswertung der Literatur ergab, dass insgesamt 9 Themenblöcke für die Entwicklung eines kompetenzorientierten Blended-Learning-Konzeptes relevant sind. 2) Die Online-Umfragen unter den Lernenden und Lehrenden der ausgewählten Berufsfachschule ergaben, dass diese bereit sind, an einzelnen Tagen bis hin zu einzelnen Wochen mit POL zu arbeiten. Die Lernenden bevorzugen analoge Lernmaterialien, während die Lehrenden sich vorstellen können, mit unterschiedlichen digitalen Materialien zu
arbeiten. 3) Das beispielhaft entwickelte kompetenzorientierte Blended-Learning-Konzept beinhaltet sowohl eine Steigerung des zeitlichen Umfangs der Lerneinheiten als auch der fachlichen Anforderungen über die Dauer der Ausbildung. Als Lernmaterialien werden digitale Präsentationen, digitale Fachliteratur sowie Videos eingesetzt. 4) Die Expert*innen schätzen das entwickelte kompetenzorientierte Blended-Learning-Konzept als umsetzbar ein und empfehlen 2 Erweiterungen.

Schlussfolgerung Es konnte, basierend auf dem entwickelten Konzeptentwicklungsprozess, ein beispielhaftes und als implementierbar eingeschätztes kompetenzorientiertes Blended-Learning-Konzept entwickelt werden. Im nächsten Schritt sollte eine wissenschaftlich begleitete Implementierung erfolgen, um die Umsetzbarkeit dieses Blended-Learning-Konzeptes zu überprüfen.
Roboter-assistierte Mikrochirurgie zur autologen
Brustrekonstruktion
Authors: Wessel Kai J , Varnava Charalampos , Wiebringhaus Philipp , Hiort Mirkka , Hirsch Tobias , Kückelhaus Maximilian
Published: April 2024

Hintergrund Durch die Einführung neuartiger Operationsroboter und
Operationsmikroskope für die speziellen Bedürfnisse der offenen Mikrochirurgie
gewinnt das Konzept der robotisch-assistierten Mikrochirurgie zunehmend an
Popularität. Während initiale präklinische Studien auf eine steile Lernkurve,
vorteilhafte Ergonomie und verbesserte Präzision bei jedoch verlängerter
Operationszeit hindeuten, sind die Daten über die klinische Anwendung der neuen
Systeme noch limitiert. Diese Studie beschreibt unsere erste klinische Erfahrung
mit der robotisch-assistierten autologen Brustrekonstruktion und stellt die
Chancen und Limitationen des Ansatzes dar.

Patienten und Methoden Es wurden insgesamt 28 Patientinnen in die
retrospektive Datenauswertung eingeschlossen, die im Zeitraum von Juli 2022 bis
August 2023 eine einseitige robotisch-assistierte autologe Brustrekonstruktion
erhielten. Dabei wurde ein kombinierter Ansatz unter Verwendung des Symani
Surgical Systems zusammen mit dem RoboticScope angewandt. Es erfolgte die
deskriptive Auswertung der Patienteneigenschaften, Operationsdaten und
Komplikationen.

Ergebnisse Das Durchschnittsalter der Patientinnen betrug 54,3±11,1 Jahre
mit einem durchschnittlichen BMI von 26,5±3,5 kg/m2. 26 Patientinnen
erhielten eine DIEP-Lappenplastik und 2 Patientinnen eine PAP-Lappenplastik, die
in 22 Fällen an die A. mammaria interna, in 5 Fällen an einen Perforator der A.
mammaria interna und in einem Fall an einen Ast der A. thoracodorsalis
angeschlossen wurden. Die durchschnittliche Schnitt-Naht-Zeit betrug 267±89 min,
bei einer durchschnittlichen Ischämiezeit von 86±20 min und Dauer der
arteriellen Anastomose von 29±12 min. In zwei Fällen erfolgte eine unmittelbar
intraoperative Anastomosenrevision, es trat jedoch kein einziger Lappenverlust
auf.

Schlussfolgerung Die Ergebnisse dieser Studie demonstrieren die sichere
Durchführbarkeit der robotisch-assistierten autologen Brustrekonstruktion
mittels kombinierter Anwendung des Symanis und des RoboticScopes. Zukünftig
sollte ein besonderes Augenmerkt auf minimalinvasive Techniken der Lappenhebung
und des Gefäßanschlusses gelegt werden.
Robotisch-assistierte Lymphchirurgie
Authors: Grünherz Lisanne , von Reibnitz Donata , Lindenblatt Nicole
Published: April 2024

In den letzten Jahren finden speziell für die Mikrochirurgie entwickelte Roboter
insbesondere in der rekonstruktiven Lymphchirurgie zunehmend Anwendung. Derzeit
gibt es zwei Robotersysteme, welche in der Mikrochirurgie eingesetzt werden.
Beide Systeme verfügen über Technologien zur Tremorreduzierung und
Bewegungsskalierung, wodurch die Präzision und Geschicklichkeit des Chirurgen
optimiert werden sollen. In der Klinik für Plastische Chirurgie und
Handchirurgie des Universitätsspitals Zürich wird das Symani Surgical System bei
vielen mikro- und supermikrochirurgischen Operationen eingesetzt. Das
Hauptanwendungsgebiet des Robotersystems liegt in der rekonstruktiven
Lymphchirurgie, im Speziellen robotisch-assistierte lymphovenöse Anastomosen,
der mikrochirurgische Anschluss des Lymphgewebslappens sowie der Anwendung in
der zentralen Lymphchirurgie. Hierbei ermöglicht die Verwendung des Roboters
kleinere Operationszugänge für anatomisch tiefe Strukturen und eine Verbesserung
der chirurgischen Präzision. In Kombination mit einem Exoskop kann es zudem die
Ergonomie des Mikrochirurgen verbessern.
Association Between Triglyceride-Glucose Index and Diabetic
Retinopathy: A Meta-Analysis
Authors: Yu Lanchu , Li Bingqing
Published: April 2024

The objective of this study was to assess the relationship between the
triglyceride-glucose (TyG) index, a recently proposed marker of insulin
resistance, and the occurrence of diabetic retinopathy (DR), a complication
associated with cardiovascular risk. This systematic review and meta-analysis
aimed to evaluate the association between the TyG index and DR. To achieve the
objective of the meta-analysis, an extensive search was conducted on databases
such as PubMed, Embase, and Web of Science to identify observational studies
with longitudinal follow-up. Random-effects models were employed to combine the
findings, taking into account the potential influence of heterogeneity. Twelve
observational studies from 11 reports were included in the meta-analysis, which
involved 16 259 patients with type 2 diabetes (T2D). Among them, 4302 (26.5%)
were diagnosed as DR. Pooled results showed that a higher TyG index was
associated with a higher risk of DR [odds ratio (OR) for the fourth versus the
first quartile of TyG index: 1.91, 95% confidence interval (CI): 1.44 to 2.53,
p<0.001; I2=72%]. Meta-analysis of TyG index analyzed in continuous variable
showed consistent results (OR for per 1 unit increment of TyG index: 1.41, 95%
CI: 1.08 to 1.86, p=0.01; I2=82%). Subgroup analysis showed that adjustment of
HbA1c or the duration of diabetes did not significantly affect the results (p
for subgroup difference all>0.05). In conclusion, a high TyG index was
associated with the risk of DR in T2D patients.
Robotic-Assisted Anastomosis in Orthoplastic Surgery: Preliminary
Data
Authors: Mori Francesco , Menichini Giulio , Rizzo Francesco , Sassu Paolo , Innocenti Marco
Published: April 2024

Background The evolution of microsurgery has relied on advancements in
operating microscopes and surgical instruments. Pioneering advancements,
however, especially within the domain of “super-microsurgery”, challenge the
limits of human dexterity by dealing with anastomoses between vessels smaller
than 0.8 mm. Based on these premises, the Symani robotic system was designed and
developed. This platform utilizes teleoperation and motion-scaled movement to
provide surgeons with precision and accuracy in manipulating millimetre and
submillimetre-sized anatomical structures. In this study, we present our
experience in performing robotic-assisted anastomoses using the Symani Surgical
System in free flap reconstruction.

Methods We present a comprehensive analysis of all reconstructive
procedures involving microsurgical free flaps performed using the Symani robotic
platform at the orthoplastic unit of the Rizzoli Orthopaedic Institute from 1
October 2022 to 1 May 2023.

Results Sixteen microsurgical reconstructions using free flaps were
performed, involving a total of 40 anastomoses on vessel calibres ranging from
0.6 mm to 2.5 mm. In each case, the anastomosis was executed with the assistance
of the robotic platform, achieving a 100+% success rate in patent anastomoses,
and no major complications occurred.

Conclusion The Symani system has proven to be safe and reliable in performing
microsurgical anastomoses. While this platform demonstrated successful in
various vessel calibres, its most promising potential lies in anastomoses below
the size of a millimetre. Larger patient cohorts and extended investigation
periods will be essential to explore whether robotics in microsurgery offers
advantages across all microsurgical procedures or should be reserved for
selected cases.
Sozialpsychiatrische Konzepte in der BRD und der DDR – Ein Vergleich
der theoretischen Ansätze von Karl Peter Kisker sowie Klaus Weise und Achim
Thom
Authors: Buttler Johann , Steinberg Holger
Published: April 2024

Die Studie zeigt in den Grundvorstellungen des Psychiaters Karl Peter Kisker
sowie des Psychiaters Klaus Weise und Philosophen Achim Thom das gemeinsame
Anliegen ab den 1960ern, psychisch Kranken zu mehr Selbstbestimmung und
gesellschaftlicher Teilhabe zu verhelfen und die Psychiatrieversorgung zu
humanisieren. Aus der Gesamtschau wird zunächst die theoretische Konzeption von
Kisker dargestellt, der ein Vertreter der westdeutschen
Sozialpsychiatriebewegung war und eine phänomenologisch-anthropologische Prägung
aufwies. In Gegenüberstellung wird der ostdeutsche Ansatz von Weise und Thom
erläutert, der an die phänomenologisch-anthropologische Subjektorientiertheit
anknüpfte, aber mit der Einbeziehung einer marxistischen Auffassung eine
sozialistische Sozialpsychiatrie begründete. Im Vergleich werden trotz vieler
Übereinstimmungen die unterschiedlichen Gewichtungen der beiden Ansätze
deutlich, die soziale Dimension des psychischen Krankseins zu verstehen.
Implementierung eines Konzepts der offenen Türen auf zwei
psychiatrischen Akutstationen an zwei Kliniken
Authors: Schreiber Lisa Katharina , Sattler Florian , Fallgatter Andreas Jochen , Steinert Tilman , Metzger Florian
Published: April 2024

Hintergrund Seit den Novellierungen der baden-württembergischen
Psychisch-Kranken-Hilfe-Gesetze können richterlich untergebrachte psychiatrische
Patienten auf offen geführten Stationen behandelt werden. Die vorliegende Arbeit
evaluiert Haltungen von Patienten und Beschäftigten in Bezug auf die
Implementierung eines Türöffnungskonzepts.

Methoden Zu Beginn und nach Abschluss der Interventionsphase wurden mit
Patienten und Personal insgesamt 8 Fokusgruppen mit jeweils 6–11 Teilnehmern
durchgeführt und qualitativ inhaltsanalytisch ausgewertet.

Ergebnisse Das Konzept offener Türen wurde tendenziell positiv
aufgenommen. Innerhalb des Personals bestanden Bedenken um Sicherheit und
Kontrolle. Auf Patientenseite erwies sich der Türstatus als begrenzt relevant
bezüglich des Erlebens von Autonomie und Stigmatisierung.

Diskussion Die Herausarbeitung von Konfliktthemen erlaubt eine
weiterführende Ausarbeitung spezifischer Konzepte zur Umsetzung offener Türen
auf psychiatrischen Akutstationen.
Colorectal polypectomy and endoscopic mucosal resection: European Society of Gastrointestinal Endoscopy (ESGE) Guideline – Update 2024
Authors: Ferlitsch Monika , Hassan Cesare , Bisschops Raf , Bhandari Pradeep , Dinis-Ribeiro Mário , Risio Mauro , Paspatis Gregorios A. , Moss Alan , Libânio Diogo , Lorenzo-Zúñiga Vincente , Voiosu Andrei M. , Rutter Matthew D. , Pellisé Maria , Moons Leon M. G. , Probst Andreas , Awadie Halim , Amato Arnaldo , Takeuchi Yoji , Repici Alessandro , Rahmi Gabriel , Koecklin Hugo U. , Albéniz Eduardo , Rockenbauer Lisa-Maria , Waldmann Elisabeth , Messmann Helmut , Triantafyllou Konstantinos , Jover Rodrigo , Gralnek Ian M. , Dekker Evelien , Bourke Michael J.
Published: April 2024

Main Recommendations

1 ESGE recommends cold snare polypectomy (CSP), to include a clear margin of normal tissue (1–2 mm) surrounding the polyp, for the removal of diminutive polyps (≤ 5 mm).

Strong recommendation, high quality of evidence.

2 ESGE recommends against the use of cold biopsy forceps excision because of its high rate of incomplete resection.

Strong recommendation, moderate quality of evidence.

3 ESGE recommends CSP, to include a clear margin of normal tissue (1–2 mm) surrounding the polyp, for the removal of small polyps (6–9 mm).

Strong recommendation, high quality of evidence.

4 ESGE recommends hot snare polypectomy for the removal of nonpedunculated adenomatous polyps of 10–19 mm in size.

Strong recommendation, high quality of evidence.

5 ESGE recommends conventional (diathermy-based) endoscopic mucosal resection (EMR) for large (≥ 20 mm) nonpedunculated adenomatous polyps (LNPCPs).

Strong recommendation, high quality of evidence.

6 ESGE suggests that underwater EMR can be considered an alternative to conventional hot EMR for the treatment of adenomatous LNPCPs.

Weak recommendation, moderate quality of evidence.

7 Endoscopic submucosal dissection (ESD) may also be suggested as an alternative for removal of LNPCPs of ≥ 20 mm in selected cases and in high-volume centers.

Weak recommendation, low quality evidence.

8 ESGE recommends that, after piecemeal EMR of LNPCPs by hot snare, the resection margins should be treated by thermal ablation using snare-tip soft coagulation to prevent adenoma recurrence.

Strong recommendation, high quality of evidence.

9 ESGE recommends (piecemeal) cold snare polypectomy or cold EMR for SSLs of all sizes without suspected dysplasia.

Strong recommendation, moderate quality of evidence.

10 ESGE recommends prophylactic endoscopic clip closure of the mucosal defect after EMR of LNPCPs in the right colon to reduce to reduce the risk of delayed bleeding.

Strong recommendation, high quality of evidence.

11 ESGE recommends that en bloc resection techniques, such as en bloc EMR, ESD, endoscopic intermuscular dissection, endoscopic full-thickness resection, or surgery should be the techniques of choice in cases with suspected superficial invasive carcinoma, which otherwise cannot be removed en bloc by standard polypectomy or EMR.

Strong recommendation, moderate quality of evidence.
On the way to deep fake democracy? Deep fakes in election campaigns in 2023
Authors: Łabuz Mateusz , Nehring Christopher
Published: April 2024

The development of generative artificial intelligence raises justified concerns about the possibility of undermining trust in democratic processes, especially elections. Deep fakes are often considered one of the particularly dangerous forms of media manipulation. Subsequent research confirms that they contribute to strengthening the sense of uncertainty among citizens and negatively affect the information environment. The aim of this study is to analyse the use of deep fakes in 11 countries in 2023, in the context of elections and to indicate potential consequences for future electoral processes, in particular with regard to the significant number of elections in 2024. We argue that a so-called “information apocalypse” emerges mainly from exaggeratedly alarmist voices that make it difficult to shape responsible narratives and may have the features of a self-fulfilling prophecy. Thus, we suggest to use the term “pollution” instead and improve scientific and journalistic discourse that might be a precondition for reducing threats that touch on social reactions to deep fakes and their potential.
Long-range distributed vibration sensing based on internal-modulation OFDR
Authors: Yue Yaoli , Zeng Jing , Ding Zhenyang , Zhang Teng , Guo Haohan , Liu Tiegen
Published: April 2024

Presented here is long-range distributed vibration sensing based on internal-modulation optical frequency domain reflectometry (OFDR). In the proposed system with internal modulation, a silicon-based photonic-chip laser is used as the laser source, and by controlling the output voltage curve of an arbitrary waveform generator to induce temperature change in the external cavity of the laser, a 10-GHz optical frequency tuning range is achieved. The complexity of the proposed internal-modulation system is lower than that of the traditional external-modulation OFDR system that combines a narrow-linewidth laser with a single-sideband modulator to achieve wavelength tuning. Cross-correlation analysis is used as a sensing mechanism to evaluate the similarity between Rayleigh scatter signals and to achieve vibration event localization. Experimental comparison is made of the vibration sensing performance of the external- and internal-modulation systems, and for a vibration event generated at a distance of 100.95 km, they locate it with a sensing spatial resolution of 43.0 m and 16.8 m, respectively. The results indicates that the proposed distributed vibration sensing based on internal modulation has better sensing performance and lower complexity compared to the traditional external-modulation system. In addition, the proposed system is single-ended and involves no optical amplification, which makes it very suitable for ultra-long-range sensing.
Atomic layer molecular beam epitaxy of kagome magnet RMn6Sn6 (R = Er, Tb) thin films
Authors: Cheng Shuyu , Liu Binzhi , Lyalin Igor , Zhou Wenyi , Hwang Jinwoo , Kawakami Roland K.
Published: April 2024

Kagome lattices have garnered substantial interest because their band structure consists of topological flat bands and Dirac cones. The RMn6Sn6 (R = rare earth) compounds are particularly interesting because of the existence of the large intrinsic anomalous Hall effect (AHE), which originates from the gapped Dirac cones near the Fermi level. This makes RMn6Sn6 an outstanding candidate for realizing the high-temperature quantum AHE. The growth of RMn6Sn6 thin films is beneficial for both fundamental research and potential applications. However, most of the studies on RMn6Sn6 have focused on bulk crystals, and the synthesis of RMn6Sn6 thin films has not been reported so far. Here, we report the atomic layer molecular beam epitaxy growth, structural and magnetic characterizations, and transport properties of ErMn6Sn6 and TbMn6Sn6 thin films. It is especially noteworthy that TbMn6Sn6 thin films have out-of-plane magnetic anisotropy, which is important for realizing the quantum AHE. Our work paves the avenue toward the control of the AHE using devices patterned from RMn6Sn6 thin films.
Nonlinear model reduction to temporally aperiodic spectral submanifolds
Authors: Haller George , S. Kaundinya Roshan
Published: April 2024

We extend the theory of spectral submanifolds (SSMs) to general non-autonomous dynamical systems that are either weakly forced or slowly varying. Examples of such systems arise in structural dynamics, fluid–structure interactions, and control problems. The time-dependent SSMs we construct under these assumptions are normally hyperbolic and hence will persist for larger forcing and faster time dependence that are beyond the reach of our precise existence theory. For this reason, we also derive formal asymptotic expansions that, under explicitly verifiable nonresonance conditions, approximate SSMs and their aperiodic anchor trajectories accurately for stronger, faster, or even temporally discontinuous forcing. Reducing the dynamical system to these persisting SSMs provides a mathematically justified model- reduction technique for non-autonomous physical systems whose time dependence is moderate either in magnitude or speed. We illustrate the existence, persistence, and computation of temporally aperiodic SSMs in mechanical examples under chaotic forcing.
ExROPPP: Fast, accurate, and spin-pure calculation of the electronically excited states of organic hydrocarbon radicals
Authors: Green James D. , Hele Timothy J. H.
Published: April 2024

Recent years have seen an explosion of interest in organic radicals due to their promise for highly efficient organic light-emitting diodes and molecular qubits. However, accurately and inexpensively computing their electronic structure has been challenging, especially for excited states, due to the spin-contamination problem. Furthermore, while alternacy or “pseudoparity” rules have guided the interpretation and prediction of the excited states of closed-shell hydrocarbons since the 1950s, similar general rules for hydrocarbon radicals have not to our knowledge been found yet. In this article, we present solutions to both of these challenges. First, we combine the extended configuration interaction singles method with Pariser–Parr–Pople (PPP) theory to obtain a method that we call ExROPPP (Extended Restricted Open-shell PPP) theory. We find that ExROPPP computes spin-pure excited states of hydrocarbon radicals with comparable accuracy to experiment as high-level general multi-configurational quasi-degenerate perturbation theory calculations but at a computational cost that is at least two orders of magnitude lower. We then use ExROPPP to derive widely applicable rules for the spectra of alternant hydrocarbon radicals, which are completely consistent with our computed results. These findings pave the way for highly accurate and efficient computation and prediction of the excited states of organic radicals.
Exploiting graded triangular gratings for optimal nano-focusing: A novel approach to enhance SERS efficiency
Authors: Zeineddine Ali , Shayegannia Moein , Kherani Nazir P. , Loh Joel Y. Y.
Published: April 2024

Plasmonic graded nano-gratings enable rainbow trapping of multiple resonant modes over a wide wavelength spectrum, useful for multi-channel Surface Enhanced Raman Spectroscopy (SERS) of molecular species. However, rectangular nano-gratings have limitations in achieving efficient rainbow trapping and localizing a wide spectrum of plasmonic modes due to their stepwise geometry, which induces high dissipation of surface plasmon polaritons into the substrate. An alternative platform of graded triangular nano-gratings enables increased localization and more efficient adiabatic transformation between neighboring grooves. Varying groove angles, depths, and periods in the tapered geometry allow for smooth adjustment of the surface plasmon polariton propagation constant, reducing losses and maximizing nano-focusing inside the groove tips. To overcome the limitation of low aspect ratio in wet-etching silicon, we employed a multi-step process of reactive ion etching of a SiO2 barrier layer to generate aperture width, followed by anisotropic wet-etching. The resulting graded triangular nano-gratings showed excellent SERS enhancement along three laser wavelength excitations. The enhancement factors of 638 and 785 nm wavelengths are 8.5 × 109 and 9 × 108, respectively, for the detection of 1 µM Rhodamine 6G. In addition, graded triangular nano-gratings show similar enhancement factors for other species, specifically the lipid DPEE-PEG, at the 532 nm laser excitation wavelength with an excellent SERS enhancement factor of 1.5 × 109. Owing to the ability of the graded triangular gratings to elicit pronounced SERS responses across three distinct laser excitations, they unequivocally qualify as “rainbow trapping” structures. Wider apertures, lower ohmic losses, and the ability to tune the groove angle beyond conventional etching methods bode well for graded triangular gratings as a superior platform for miniature sensors.
A generalized model for tribovoltaic nanogenerator
Authors: Guo Xin , You Jing , Wei Di , Shao Jiajia , Wang Zhong Lin
Published: April 2024

Converting mechanical energy into direct-current electric power based on the tribovoltaic effect is a typical characteristic of tribovoltaic nanogenerators (TVNGs). Although this newly discovered physics effect has been devoted to numerous research studies recently, a generalized theoretical model is still missing, thus unable to comprehensively elaborate the working principles of TVNG. Unlike previous qualitative explanations restricted to the conventional diffusion-drift theory, a new theoretical model is proposed according to classical semiconductor physics. Using the model, the governing equation of a TVNG is derived for the first time, which provides possibilities for revealing the variations of basic physical variables whether within the device or in an external circuit. The direct-current output is suggested to be the coupling of the tribovoltaic effect and contact electrification; in detail, it directly results from the movement and realignment of quasi-Fermi levels for excess carriers that are contiguous to the junction/contacting interface under non-equilibrium conditions. Moreover, an equivalent circuit model is established, equivalent to a constant current source parallel to a p–n junction diode according to the lumped parameter circuit theory. Notably, a new term, mechano-induced electric field EM, is defined and introduced to describe the impact of triboelectric charges at interfaces. Furthermore, using the COMSOL Multiphysics software, a dynamic simulation model for TVNGs is proposed, allowing the simulation and calculation of various TVNGs with different geometric constructions and charge distributions.
Analyzing multi-step reaction mechanisms: Unveiling non-linear dynamics with advanced reduction techniques
Authors: Yaseen Muhammad , Sultan Faisal , Ishaq Muhammad Shoaib , Shahzad Muhammad , Chambashi Gilbert
Published: April 2024

This study aims to achieve the computational results for the oxidation of carbon monoxide using the spectral quasi-equilibrium manifold and the intrinsic low-dimensional manifold techniques, enabling the identification of the slow invariant manifold and subsequent simulation of the solutions. In addition, the application of Gibbs’ rule facilitates the reduction of the system, thereby effectively transforming higher dimensions into lower dimensions, ultimately revealing the underlying 1D manifold dynamics. This research serves to elucidate the intricacies of phase-shifting behaviors in the context of key species within the overarching and interconnected multi-step reaction mechanisms, contributing significantly to the advancement of understanding in this complex field.
Predicting turbulent wake flow of marine hydrokinetic turbine arrays in large-scale waterways via physics-enhanced convolutional neural networks
Authors: Zhang Zexia , Sotiropoulos Fotis , Khosronejad Ali
Published: April 2024

We present a physics-enhanced convolutional neural network (PECNN) algorithm for reconstructing the mean flow and turbulence statistics in the wake of marine hydrokinetic (MHK) turbine arrays installed in large-scale meandering rivers. The algorithm embeds the mass and momentum conservation equations into the loss function of the PECNN algorithm to improve the physical realism of the reconstructed flow fields. The PECNN is trained using large eddy simulation (LES) results of the wake flow of a single row of turbines in a virtual meandering river. Subsequently, the trained PECNN is applied to predict the wake flow of MHK turbines with arrangements and positionings different than those considered during the training process. The PECNN predictions are validated using the results of separately performed LES. The results show that the PECNN algorithm can accurately predict the wake flow of MHK turbine farms at a small fraction of the cost of LES. The PECNN can improve the accuracy by around 1% and reduce the physical constraint indices by around 50% compared to the CNN without physical constraints. This work underscores the potential of PECNN to develop reduced-order models for control co-design and optimization of MHK turbine arrays in natural riverine environments.
A population balance model for the kinetics of covalent organic framework synthesis
Authors: Weatherspoon Howard , Peters Baron
Published: April 2024

This study presents a population balance model for the kinetics of nucleation and growth in covalent organic framework (COF) synthesis. The model incorporates second-order nucleation and first-order growth rates, consistent with proposals in the literature. Despite having non-linear terms, an implicit analytic solution is derived and then converted to explicit solutions for the monomer concentration and size distribution of COF flakes as a function of time. For experimental definitions of the induction time and the initial growth rate based on yield (y) vs time (t) curves, the model predicts power-law relationships: tind=0.409kN−1/3kG−2/3cA0−1 and dy/dtmax=0.965kN1/3kG2/3cA0, respectively. We discuss the implications for the interpretation of Arrhenius plots. We also discuss key discrepancies with experiments, including the predicted attainment of 100% yield instead of 30%–40% as observed and the value of the yield at the inflection point in the yield vs time curve. We suggest extensions to the model, including nucleation and growth kinetics with equilibrium solubility limitations and two-dimensional nucleation for the formation of multilayer COF particles.
Observation of fast Alfvén wave in KAERI plasma beam irradiation facility using an applied-field MPD thruster
Authors: Chai Kil-Byoung , Shin Changmin , Yoon Young Dae , Seung Minuk , Kwon Inyong
Published: April 2024

Electromagnetic fluctuations between 300 and 500 kHz were observed in both ion saturation current and magnetic field measurements in the KAERI plasma beam irradiation facility where the applied-field magnetoplasmadynamic (MPD) thruster is used as a plasma source. In this study, the plasmas were ignited with deuterium gas and the plasma current (input power) was varied from 55 A (2 kW) to 155 A (6 kW). The electron temperature and density measured downstream of the MPD thruster plasma were ∼5 eV and (2–4) × 1012 cm−3, respectively. To identify the fluctuations, the dispersion relation and the phase velocity were experimentally obtained using the Beall method and were compared to the theoretical values under warm plasma conditions. It was revealed that the observed fluctuations were fast Alfvén waves with a circularly polarized magnetic field. In addition to the fast Alfvén waves, we also observed electrostatic fluctuations at a higher frequency that was similar to the lower-hybrid frequency.
4H–SiC microring resonators—Opportunities for nonlinear integrated optics
Authors: Afridi Adnan Ali , Lu Yaoqin , Shi Xiaodong , Wang Ruixuan , Li Jingwei , Li Qing , Ou Haiyan
Published: April 2024

Silicon carbide, a wide bandgap semiconductor material platform, has emerged as an exceptional material for nonlinear integrated photonics. Among the different poly-structures, 4H-silicon carbide-on-insulator stacks show promising results to their low loss, which are crucial for commercial applications like communication, metrology, and spectroscopy. High Q-values and low-loss microring resonators are imperative for miniaturization and photonic integration in these applications. This Perspective emphasizes recent advancements in enhancing the quality factor of microresonators based on 4H-silicon carbide, as well as the strides made in experimental results of third-order nonlinearities. Furthermore, this Letter addresses and outlines the prospects of integrating 4H-silicon carbide microring resonators into frequency comb technologies and potential applications.
Physics-constrained and flow-field-message-informed graph neural network for solving unsteady compressible flows
Authors: Li Siye , Sun Zhensheng , Zhu Yujie , Zhang Chi
Published: April 2024

With the increasing use of deep neural networks as surrogate models for accelerating computational simulations in mechanics, the application of artificial intelligence in computational fluid dynamics has seen renewed interest in recent years. However, the application of deep neural networks for flow simulations has mainly concentrated on relatively simple cases of incompressible flows. The strongly discontinuous structures that appear in compressible flows dominated by convection, such as shock waves, introduce significant challenges when approximating the nonlinear solutions or governing equations. In this work, we propose a novel physics-constrained, flow-field-message-informed (FFMI) graph neural network for spatiotemporal flow simulations of compressible flows involving strong discontinuities. To enhance the nonlinear approximation capability of strong discontinuities, a shock detector method is leveraged to extract the local flow-field messages. These messages are embedded into the graph representation to resolve the discontinuous solutions accurately. A new FFMI sample-and-aggregate-based message-passing layer, which aggregates the edge-weighted attributes with node features on different hop layers, is then developed to diffuse and process the flow-field messages. Furthermore, an end-to-end paradigm is established within the encoder–decoder framework to transform the extracted information from the flow field into latent knowledge about the underlying fluid mechanics. Finally, a variety of one- and two-dimensional cases involving strong shock waves are considered to demonstrate the effectiveness and generalizability of the proposed FFMI graph neural network.
Drift wave soliton formation via beat-driven zonal flow and implication on plasma confinement
Authors: Chen Ningfei , Chen Liu , Zonca Fulvio , Qiu Zhiyong
Published: April 2024

In this work, gyrokinetic theory of drift waves (DWs) self-regulation via the beat-driven zonal flow (ZF) is presented, and finite diamagnetic drift frequency due to plasma nonuniformity is shown to play a dominant role in the ZF beat generation. The obtained nonlinear DW equation is a nonlinear Schrödinger equation, in which the linear dispersiveness, linear growth, nonuniformity of diamagnetic drift frequency, and cubic nonlinearity induced by the feedback of beat-driven ZF to DWs are self-consistently included. The nonlinear DW equation is solved numerically in both uniform and nonuniform plasmas. It is shown that the DW envelope soliton may form due to the balance of linear dispersiveness and nonlinearity and lead to turbulence spreading to linearly stable region. It is further found that though the threshold on the DW amplitude for soliton formation is well within the relevant parameter regimes of realistic tokamak experiments, solitons cannot extend beyond the range bounded by the turning points of the wave packet when plasma nonuniformity is self-consistently accounted for.
NH3 adsorption and competition with H2O on a hydroxylated aluminosilicate surface
Authors: Franceschi Giada , Conti Andrea , Lezuo Luca , Abart Rainer , Mittendorfer Florian , Schmid Michael , Diebold Ulrike
Published: April 2024

The interaction between ammonia (NH3) and (alumino)silicates is of fundamental and applied importance, yet the specifics of NH3 adsorption on silicate surfaces remain largely unexplored, mainly because of experimental challenges related to their electrically insulating nature. An example of this knowledge gap is evident in the context of ice nucleation on silicate dust, wherein the role of NH3 for ice nucleation remains debated. This study explores the fundamentals of the interaction between NH3 and microcline feldspar (KAlSi3O8), a common aluminosilicate with outstanding ice nucleation abilities. Atomically resolved non-contact atomic force microscopy, x-ray photoelectron spectroscopy, and density functional theory-based calculations elucidate the adsorption geometry of NH3 on the lowest-energy surface of microcline, the (001) facet, and its interplay with surface hydroxyls and molecular water. NH3 and H2O are found to adsorb molecularly in the same adsorption sites, creating H-bonds with the proximate surface silanol (Si–OH) and aluminol (Al–OH) groups. Despite the closely matched adsorption energies of the two molecules, NH3 readily yields to replacement by H2O, challenging the notion that ice nucleation on microcline proceeds via the creation of an ordered H2O layer atop pre-adsorbed NH3 molecules.
Probing the electronic structure and ground state symmetry of gas phase C60+ via VUV photoionization and comparison with theory
Authors: Hrodmarsson Helgi Rafn , Rapacioli Mathias , Spiegelman Fernand , Garcia Gustavo A. , Bouwman Jordy , Nahon Laurent , Linnartz Harold
Published: April 2024

Recently, some of us reviewed and studied the photoionization dynamics of C60 that are of great interest to the astrochemical community as four of the diffuse interstellar bands (DIBs) have been assigned to electronic transitions in the C60+ cation. Our previous analysis of the threshold photoelectron spectrum (TPES) of C60 [Hrodmarsson et al., Phys. Chem. Chem. Phys. 22, 13880–13892 (2020)] appeared to give indication of D3d ground state symmetry, in contrast to theoretical predictions of D5d symmetry. Here, we revisit our original measurements taking account of a previous theoretical spectrum presented in the work of Manini et al., Phys. Rev. Lett. 91(19), 196402 (2003), obtained within a vibronic model parametrized on density functional theory/local-density approximation electronic structure involving all hg Jahn–Teller active modes, which couple to the 2Hu components of the ground state of the C60+ cation. By reanalyzing our measured TPES of the ground state of the C60 Buckminsterfullerene, we find a striking resemblance to the theoretical spectrum calculated in the work of Manini et al., Phys. Rev. Lett. 91(19), 196402 (2003), and we provide assignments for many of the hg modes. In order to obtain deeper insights into the temperature effects and possible anharmonicity effects, we provide complementary modeling of the photoelectron spectrum via classical molecular dynamics (MD) involving density functional based tight binding (DFTB) computations of the electronic structure for both C60 and C60+. The validity of the DFTB modeling is first checked vs the IR spectra of both species which are well established from IR spectroscopic studies. To aid the interpretation of our measured TPES and the comparisons to the ab initio spectrum we showcase the complementarity of utilizing MD calculations to predict the PES evolution at high temperatures expected in our experiment. The comparison with the theoretical spectrum presented in the work of Manini et al., Phys. Rev. Lett. 91(19), 196402 (2003), furthermore, provides further evidence for a D5d symmetric ground state of the C60+ cation in the gas phase, in complement to IR spectroscopy in frozen noble gas matrices. This not only allows us to assign the first adiabatic ionization transition and thus determine the ionization energy of C60 with greater accuracy than has been achieved at 7.598 ± 0.005 eV, but we also assign the two lowest excited states (2E1u and 2E2u) which are visible in our TPES. Finally, we discuss the energetics of additional DIBs that could be assigned to C60+ in the future.
Evaluation of survival weighted Pareto distribution: Analytical properties and applications to industrial and aeronautics data
Authors: Nagy M. , Ahmad Mashhood , Jabeen Riffat , Zaka Azam , Alrasheedi Adel Fahed , Mansi A. H.
Published: April 2024

In statistical modeling, lifetime datasets play an important and significant role. Weighted distributions can be useful to attain the essential purposes relating to the developed distributions’ flexibility and to improve further compliances in data forming; they provide the extension of distributions. The current study suggests a new best-fit probability distribution model based on Pareto distribution. The new model is called Survival Weighted Pareto (SWP) distribution model. Furthermore, the statistical expressions for different properties, which include moments, inverse moments, quantile function, and order statistics, are reported. Moreover, to check the performance and the behavior of different estimators using different sample sizes, a simulation study, which is based on SWP distribution, is performed. According to the simulation results, it is established that the proposed model is a most useful fitted probability model. In addition, an application of the SWP model for three datasets is provided to check the goodness of fit measures of the model.
Mass transport at the bottom of propagating surface waves over a rippled bottom
Authors: Vittori Giovanna , Blondeaux Paolo
Published: April 2024

The sea surface can be described by means of the superposition of many sinusoidal functions. However, quite often the amplitude of each component turns out to be much smaller than its wavelength, and any component evolves independently of the others. Hence, it is common to investigate the dynamics of a simple monochromatic surface wave. Hereinafter, the flow generated by a monochromatic surface wave within the bottom boundary layer over a rippled sea bed is determined by means of the numerical integration of vorticity and continuity equations. The forcing term that drives the fluid motion within the boundary layer is evaluated assuming that the steepness of the monochromatic surface wave is much smaller than one and considering the first term of the Stokes expansion. Even though the irrotational flow that forces the viscous rotational flow near the sea bottom is symmetric with respect to the ripple crests, Blondeaux and Vittori [“A route to chaos in an oscillatory flow: Feigenbaum scenario,” Phys. Fluids A 3(11), 2492–2495 (1991a)] showed that the symmetry of the flow field is broken when the Reynolds number becomes larger than a threshold value Rδ,t1 that depends on the geometrical characteristics of the ripples. The results of Blondeaux and Vittori [“A route to chaos in an oscillatory flow: Feigenbaum scenario,” Phys. Fluids A 3(11), 2492–2495 (1991a)] suggest that, when the Reynolds number is larger than Rδ,t1 but not too far from it, a steady current is also generated. Hereinafter, the steady velocity component is determined as a function of the ripple characteristics.
VAMPyR—A high-level Python library for mathematical operations in a multiwavelet representation
Authors: Bjørgve Magnar , Tantardini Christian , Jensen Stig Rune , Gerez S. Gabriel A. , Wind Peter , Di Remigio Eikås Roberto , Dinvay Evgueni , Frediani Luca
Published: April 2024

Wavelets and multiwavelets have lately been adopted in quantum chemistry to overcome challenges presented by the two main families of basis sets: Gaussian atomic orbitals and plane waves. In addition to their numerical advantages (high precision, locality, fast algorithms for operator application, linear scaling with respect to system size, to mention a few), they provide a framework that narrows the gap between the theoretical formalism of the fundamental equations and the practical implementation in a working code. This realization led us to the development of the Python library called VAMPyR (Very Accurate Multiresolution Python Routines). VAMPyR encodes the binding to a C++ library for multiwavelet calculations (algebra and integral and differential operator application) and exposes the required functionality to write a simple Python code to solve, among others, the Hartree–Fock equations, the generalized Poisson equation, the Dirac equation, and the time-dependent Schrödinger equation up to any predefined precision. In this study, we will outline the main features of multiresolution analysis using multiwavelets and we will describe the design of the code. A few illustrative examples will show the code capabilities and its interoperability with other software platforms.