bluuebunny/crossref_metadata_2025 huggingface dataset:
Developing speed‐related safety performance indicators from floating car data
Authors: Ambros Jiří , Usami Davide Shingo , Valentová Veronika
Published: October 2022

In the road traffic safety domain there is a need for using proactive (non‐crash‐based) indicators, known as safety performance indicators (SPIs). Traffic speed based on big data (floating car data [FCD]) could help develop network‐wide SPIs, but related knowledge and experience are insufficient so far. The authors attempted to fill this gap by using nationwide Italian FCD to develop speed‐related SPIs and validating their relationship to crashes to see their potential explanatory value. The authors calculated the coefficient of variance (CV), congestion index (CI), and the number of incidents as candidate SPIs. For validation, the authors used linear correlation, crash frequency model, and ranking consistency. Incidents turned out to be the best SPI, especially for motorways.
Advanced control scheme and dynamic phasor modelling of grid‐tied droop‐controlled inverters
Authors: Bendib Ahmed , Kherbachi Abdelhammid , Chouder Aissa , Ahmed Hafiz , Kara Kamel
Published: October 2022

This paper develops an advanced scheme, modelling, and analysis of power flow control intended for grid‐connected droop‐controlled VSIs within a single‐phase microgrid (MG). The proposed control scheme includes a power calculation method based on an enhanced second‐order generalized integrator frequency‐locked loop (ESOGI‐FLL). Contrary to the existing power calculation methods that use low‐pass filter (LPF) with a low cutoff frequency to reject the grid voltage distortion and achieve average power, which may result in reducing the power calculation speed, the involved ESOGI‐FLL can offer a fast transient response and benefits from high filtering capability of sub‐ and low‐order harmonics. In addition, the ESOGI‐FLL provides total rejection of the DC offset, which is another issue that may adversely affect the accuracy of the traditional methods. Thus, this proposal can contribute to improving the speed and accuracy of the power computation and make the power calculation scheme immune to DC disturbance, thereby enhancing the performance of the power control. On the other hand, a dynamic phasor modelling approach is adopted considering the dynamics of the ESOGI‐based power calculation, instead of the LPF transfer function used to describe the power computation dynamic in the related works. The small‐signal model of the grid‐connected VSI power flow considering the line impedance R/X ratio as well as that describing the dynamics of the ESOGI‐based power calculation are derived. Using these models, the closed‐loop model of the grid‐interactive inverter including the power controller dynamics is obtained. The system stability is assessed, which helps to determine properly the controller's gains. A simulation study of a grid‐connected VSI is carried out in MATLAB/Simulink™ and PSIM's processor in the loop (PIL) platforms to assess the effectiveness of the proposed control approach. The results confirm the effectiveness of the proposed control to regulate real and reactive powers with good transient performances when the grid is subject to several working conditions.
Single channel blind source separation of complex signals based on spatial‐temporal fusion deep learning
Authors: Luo Weilin , Yang Ruijuan , Jin Hongbin , Li Xiaobai , Li Hao , Liang Kangbo
Published: October 2022

Blind Source Separation (BSS) of complex signals composed of radar, communication and jamming signals is the first step in an integrated electronic system, which requires higher accuracy of separation. However, the traditional Single‐Channel Blind Source Separation (SCBSS) method has low separation accuracy and poor robustness. Aiming at this problem, this paper proposes a SCBSS method based on spatial‐temporal fusion deep learning model. This is a deep neural network model, which realizes spatial‐temporal of mixed signals by integrating Convolutional Neural Network (CNN) and Bidirectional Long Short‐Term Memory Network (BiLSTM). Convolutional Neural Network is used to extract spatial features from input sequences, and BiLSTM is used to mine timing rules of signals. A batch normalisation layer and a dropout layer are added to improve stability and prevent overfitting. The experiments show that the average similarity coefficient of the separated signals is above 0.99 and the Signal‐Distortion Ratio (SDR) is up to 27 dB without noise. When the Signal‐Noise Ratio is 0–20 dB and Jamming‐Signal Ratio is 15 dB, the SDR is 5–30 dB higher than the traditional methods and the single network structure deep learning methods.
Somatisierung, Depressivität und Angst bei Binnenmigrierten
in einer deutschen repräsentativen Stichprobe
Authors: Otten Daniëlle , Heller Ayline , Kasinger Christoph , Brähler Elmar , Sachser Cedric , Altweck Laura , Beutel Manfred E. , Fegert Jörg M.
Published: October 2022

Ziel der Studie Das Ziel dieser Studie ist es, zu untersuchen, inwiefern
innerdeutsche Migration (Binnenmigration) mit allgemeiner psychischer Belastung,
Somatisierung, Depressivität und Angst assoziiert ist.

Methode Daten aus zwei bevölkerungsrepräsentativen
Befragungen (2020 und 2021; N=4922) wurden genutzt, um mit Hilfe von
linearen Regressionsanalysen den Einfluss von Binnenmigration auf psychische
Gesundheit zu untersuchen. Die allgemeine psychische Belastung mit den
Dimensionen Somatisierung, Depressivität und Angst wurde mit der
Kurzform des Brief Symptom Inventory (BSI-18) erfasst. Außerdem wurden
soziodemographische Merkmale (Geschlecht, Alter, Partnerschaft,
Haushaltsäquivalenzeinkommen und Bildung) kontrolliert.

Ergebnisse Binnenmigrierte vom Osten in den Westen berichteten, auch nach
Kontrolle der soziodemografischen Faktoren, signifikant höhere Werte in
der allgemeinen psychischen Belastung, Somatisierung, Depressivität und
Angst als Personen, die im Osten aufgewachsen und geblieben sind. Es wurden
keine Unterschiede gefunden zwischen Binnenmigrierten vom Westen in den Osten
und Personen, die im Westen aufwuchsen und zur Zeit der Befragung noch im Westen
lebten.

Fazit Der Vergleich von psychischer Gesundheit in den neuen und alten
Bundesländern sollte Binnenmigration als wichtigen Faktor
berücksichtigen. Unsere Ergebnisse zeigen, dass sich insbesondere bei
den Binnenmigrierten von Ost nach West eine erhöhte psychische Belastung
findet.
Bedarf an Fortbildung für
Funktionsträger*innen von
Krebs-Selbsthilfeorganisationen
Authors: Jablotschkin Martina , Sauer Nicola , Jäger Martina , Kerek-Bodden Hedy , Kubitza Werner , Weis Joachim
Published: October 2022

Ziel der Studie Im Rahmen des Zentrums für Kompetenzentwicklung in
der Krebs-Selbsthilfe am Universitätsklinikum Freiburg wurde eine
Analyse des Bedarfs an Schulungen und Fortbildungen unter den
Mitgliedsverbänden des Hauses der Krebs-Selbsthilfe (HKSH)
durchgeführt.

Methodik Die Online-Befragung erfolgte im Februar bis April 2021 und wurde
von Funktionsträger*innen auf verschiedenen Organisationsebenen
und Gruppenteilnehmer*innen ausgefüllt. In einem gemeinsam mit
Selbsthilfevertreter*innen entwickelten Fragebogen wurden potentielle 19
Schulungsthemen bezüglich ihrer Wichtigkeit eingestuft. Zudem wurde
erfasst, ob das jeweilige Thema durch bereits vorhandene Qualifizierungsangebote
als ausreichend abgedeckt wahrgenommen wurde. Im Rahmen eines
forced-choice-Ansatzes benannten die Befragten abschließend die
für sie fünf wichtigsten Themen.

Ergebnisse Die Themen, die ein besonders hoher Anteil der N=293
Befragten als „sehr wichtig“ identifizierten und die zugleich
durch bereits bestehende Angebote als unzureichend adressiert wahrgenommen
wurden, waren der Umgang mit belastenden Themen (z. B. Rezidiv,
Metastasen, Sterben), die Gewinnung von neuen Mitgliedern und
Nachfolger*innen für Verbandsaufgaben, sozialrechtliche Aspekte
sowie Gesprächsführung und kommunikative Kompetenzen. In der
Priorisierung der fünf wichtigsten Themen bildeten sich die drei
erstgenannten Themen erneut ab, wobei an vierter Stelle Umgang mit
Überforderung und Hilfestellungen zur
Selbstfürsorge/Burn-Out-Prävention folgte und an
fünfter Stelle mit jeweils gleicher Stimmenzahl die Themen Kenntnisse im
Umgang mit Komplementärmedizin und Kenntnisse professioneller
Versorgungsstrukturen in der Onkologie.

Diskussion Es zeigte sich ein deutlicher Bedarf an thematisch breit
gefächerten Fortbildungsthemen, der über die bestehenden
Angebote der Krebs-Selbsthilfeverbände hinausgeht. Durch die
Bedarfsanalyse konnten die Themen identifiziert werden, die
organisationsübergreifend in allen zehn Mitgliedsverbänden des
HKSH als Schulungs- und Fortbildungsthemen priorisiert werden.

Schlussfolgerung Auf der Basis dieser Bedarfserhebung können in
Kooperation mit den Patientenvertreter*innen des HKSH die jeweiligen
Fortbildungen priorisiert und umgesetzt werden.
Wirksamkeitsfokussierte Bewertung von internetbasierten
Interventionen: ein Studienprotokoll
Authors: Köhnen Moritz , Härter Martin , Sander Julia , Gerlinger Gabriel , Dirmaier Jörg
Published: October 2022

Hintergrund Das Angebot von internetbasierten Interventionen zur
Behandlung psychischer Erkrankungen nimmt stetig zu und ist mittlerweile auch in
der Versorgung verankert. Allerdings ist die Informationslage für
Behandelnde und Nutzende insbesondere in Bezug auf die Wirksamkeit
internetbasierter Interventionen noch ausbaufähig.

Ziele Es sollen deutschsprachige internetbasierte Interventionen zur
Behandlung psychischer Erkrankungen, gelistet im DiGA-Verzeichnis, identifiziert
und evaluiert werden. Positiv begutachtete Interventionen sollen anschaulich
für Interessierte bei psychenet.de dargestellt werden.

Methodik Mittels vorab festgelegter Kriterien zur
Interventionsidentifikation, -bewertung und anschließender Publikation
bei psychenet.de soll ein wissenschaftlich fundiertes und transparentes Vorgehen
etabliert und in der Praxis umgesetzt werden.

Ethik &
Dissemination Das Einholen eines Ethikvotums war nicht
notwendig, da das Vorhaben auf bereits publizierten Daten basiert. Es sollen
relevante Fach- und Betroffenenverbände über das bei
psychenet.de veröffentlichte Angebot informiert werden.
Personale Ressourcen von Jugendlichen in Ost- und Westdeutschland
– Ergebnisse der KiGGS-Studie 15 und 25 Jahre nach der
Wende
Authors: Schmidtke Claudia , Hövener Claudia , Nowossadeck Enno , Lampert Thomas , Hölling Heike , Michalski Niels
Published: October 2022

Fragestellung Gab es über 15 Jahre nach der deutschen
Wiedervereinigung Unterschiede in den personalen Ressourcen bei den um 1989
geborenen Kindern und Jugendlichen zwischen Ost und West? Wie haben sich die
Unterschiede dieser „Wendegeneration“ in der Folge
entwickelt?

Methode Daten der KiGGS-Studie aus den Jahren 2003–2006 und
2014–2017 werden genutzt, um bei 14–17-jährigen
Jugendlichen der Wendegeneration die Häufigkeiten geringer personaler
Ressourcen in Ost und West zu bestimmen. Es werden Querschnittsdaten zu beiden
Erhebungszeitpunkten zwischen Ost und West verglichen und
Längsschnittdaten verwendet, um die Kohorte im Altersverlauf zu
verfolgen.

Ergebnisse 14–17-Jährige aus Ostdeutschland zeigen rund 15
Jahre nach der Wende häufiger geringere personale Ressourcen und haben
eine geringere Selbstwirksamkeitserwartung als gleichaltrige Jugendliche im
Westen Deutschlands. 10 Jahre später sind die Unterschiede kaum noch
sichtbar und haben sich zum Teil umgekehrt. Die gefundenen Ost-West-Unterschiede
lassen sich nicht durch unterschiedliche sozioökonomische Lagen der
Familien in Ost und West erklären.

Fazit Die Ergebnisse zeigen, dass um 1989 geborene Jugendliche aus Familien
mit DDR-Sozialisation, unabhängig vom SES, noch in den 2000er Jahren ein
höheres Risiko geringerer personaler Ressourcen aufwiesen als
Jugendliche aus BRD-Familien. 25 Jahre nach der Wende war dies nicht mehr
erkennbar. Während die Unterschiede zwischen Ost und West im Zeitverlauf
abnehmen, nimmt die Bedeutung der sozioökonomischen Lage der Familien
für die personalen Ressourcen der Jugendlichen insgesamt jedoch zu und
zwar zuungunsten derer mit niedrigem sozioökonomischen Status. Die
Ergebnisse weisen auf die Notwendigkeit von gezielter Ressourcenstärkung
bei Kindern und Jugendlichen in Phasen von Transformation und biografischen
Brüchen hin.
Geschlechts- und regionalspezifische Unterschiede von
Kindesvernachlässigung und Gewalt vor der deutschen Wiedervereinigung.
Ergebnisse aus GESA, einem Multi-Kohorten Konsortium
Authors: Fleischer Toni , Ulke Christine , Ladwig Karl-Heinz , Linkohr Birgit , Johar Hamimatunnisa , Atasoy Seryan , Speerforck Sven , Kruse Johannes , Zöller Daniela , Binder Harald , Otten Danielle , Brähler Elmar , Beutel Manfred E. , Tibubos Ana N. , Grabe Hans Jörgen , Schomerus Georg
Published: October 2022

Erste Ergebnisse einer bundesweiten Studie deuten auf geschlechtsspezifische
Muster mit weniger berichteten Fällen von Kindesvernachlässigung
und Gewalt in den Neuen im Vergleich zu den Alten Bundesländern. Ziel
der vorliegenden Studie war es diese Ergebnisse in zwei größeren
regionalen Stichproben zu überprüfen. Methode:
Prävalenzen von Vernachlässigung- und Gewalterfahrung in der
Kindheit wurden mithilfe des Childhood Trauma Screeners in den Regionen
Greifswald (SHIP, 2008–2012) und Augsburg (KORA, 2013–2014)
erhoben. Analyse geschlechtsstratifizierter und regionaler Unterschiede. Die
Prävalenzen beider lokalen Stichproben wurden anschließend
miteinander verglichen. Ergebnisse: Insgesamt wurden Vernachlässigung
und Gewalt in der Kindheit seltener in der Nord-Ostdeutschen Stichprobe (SHIP)
berichtet. Die deutlichsten Unterschiede fanden sich in den Kategorien
emotionale Gewalt (SHIP: 6,1%, KORA: 8,7%), körperliche
Gewalt (SHIP: 5,7%, KORA: 10,3%) sowie körperliche
Vernachlässigung (SHIP:10,0%, KORA: 19,2%).
Geschlechtsspezifische Muster von Vernachlässigungs- und Gewalterfahrung
in der Kindheit unterschieden sich in SHIP und KORA nicht. Schlussfolgerung: Wir
diskutieren den möglichen Einfluss des sozio-politischen Kontexts auf
die Prävalenz von Vernachlässigung und Gewalt in der Kindheit,
da alle selbstberichteten Ereignisse in die Zeit vor der Wiedervereinigung in
zwei politisch unterschiedliche Systeme fallen.
Association between Self-reported Overtraining Syndrome and Symptoms
in High School Track and Field Athletes
Authors: Tsukahara Yuka , Kamada Hiroshi , Torii Suguru , Yamasawa Fumihiro
Published: October 2022

Diagnosing overtraining syndrome is challenging and it is often correlated with
other diseases, especially those related to low energy availability. Therefore,
we investigated the prevalence of overtraining syndrome-like symptoms and
correlative factors in 389 female and 572 male national-level high school track
and field athletes. They were asked to complete a survey regarding their history
of overtraining syndrome-like symptoms, injuries, and diseases. The survey
results revealed that 13.4% (52/389) of female and 13.3%
(76/572) of male athletes had a history of overtraining syndrome-like
symptoms. Logistic regression analysis showed that training hours per day (odds
ratio, 1.74; 95% confidence interval, 1.12–2.71) was an
associated factor in female athletes, while rest days per week (odds ratio,
0.61; 95% confidence interval, 0.37–1.00), skipping meals (odds
ratio, 3.73; 95% confidence interval, 1.50–9.29), and having
snacks/light meals on a regular basis (odds ratio, 0.46; 95%
confidence interval, 0.26–0.83) were the associated factors in male
athletes. In conclusion, athletes with overtraining syndrome-like symptoms may
be prone to injuries and diseases. Hence, although overtraining syndrome is
difficult to diagnose, further attention should be paid to minimize overtraining
syndrome-related risks.
Influence of Heat Treatment of Nickel–Titanium Instruments on Cyclic Fatigue Resistance in Simulated Curved Canals
Authors: Campos Gustavo Oliveira , Fontana Carlos Eduardo , Vieira Victor Talarico Leal , Elias Carlos Nelson , de Martin Alexandre Sigrist , Bueno Carlos Eduardo da Silveira
Published: October 2022

Objective The aim of this study was to compare the cyclic fatigue of heat-treated and non-treated instruments.

Materials and Methods Twenty instruments with and without heat treatment from Bassi Logic were evaluated (n = 10). All instruments were subjected to dynamic cyclic fatigue through continuous rotations inside a stainless-steel tube (1.4-mm diameter, 9-mm curvature with 6-mm radius, and 90° angle) using a custom-made device, which performed 1 axial oscillation every 2 seconds with an amplitude of 3 mm, powered by a torque-controlled motor (Silver Reciproc, VDW, Germany), with speed adjusting to 950 rpm and torque to 4 N, according to manufacturer's guidance. The groups were compared using the Mann–Whitney test.

Result The fracture time of the heat-treated instruments (97.20 ± 39.94 second and non-treated instruments (14.30 ± 6.78 seconds had statistical differences [p < 0.05]). Heat-treated instruments were 6.8 times more resistant to fatigue than non-treated instruments (p < 0.05).

Conclusion Heat treatment provides increased fatigue resistance of NiTi alloy with the same design.
Gaining Soft Tissue with a Hydrogel Soft Tissue Expander: A Case Report
Authors: Uijlenbroek Henri J.J. , Liu Yuelian , Wismeijer Daniel
Published: October 2022

In this case report, we describe the treatment of a patient referred to our clinic with a hopeless tooth 21 with an attached pontic. The aim of this case report was to, first, describe the advantages and disadvantages of gaining soft tissue with a self-inflating soft tissue expander before performing a bone augmentation procedure in implant dentistry in the esthetic zone. Second, we describe how an amalgam tattoo, caused by a previously performed apicoectomy that made the extension of the raised flap to cover the augmented site esthetically undesirable, was removed. Two silicone enveloped Osmed hydrogel self-inflating soft tissue expanders were placed submucosally on the right- and left-hand side of the amalgam tattoo. One of these two perforated the overlaying mucosa after 24 days. Both tissue expanders were removed, the amalgam tattoo was excided, the site augmented, and an implant with a crown and a pontic was placed.
Reducing infection risk in multiple sclerosis and neuromyelitis optica spectrum disorders: a Brazilian reference center's approach
Authors: Gomes Ana Beatriz Ayroza Galvão Ribeiro , Feo Lucas Bueno , Silva Guilherme Diogo , Disserol Caio César Diniz , Paolilo Renata Barbosa , Lara Amanda Nazareth , Tonácio Adriana Coracini , Mendes Maria Fernanda , Pereira Samira Luísa Apóstolos , Callegaro Dagoberto
Published: October 2022

Background Multiple sclerosis (MS) and neuromyelitis optica spectrum disorders (NMOSD) are the most common autoimmune diseases of the central nervous system (CNS). They present chronic relapsing courses that demand treatment with disease-modifying drugs (DMDs) to prevent inflammatory activity. Disease-modifying drugs lead to immunomodulation or immunosuppression through diverse mechanisms (e.g., shifting lymphocyte and cytokine profile, suppressing specific lymphocyte subpopulations). Thus, patients are more prone to infectious complications and associated worsening of disease.

Objective To present feasible strategies for mitigating the infection risk of MS and NMOSD treated patients.

Methods Targeted literature review concerning the management of infection risk with an emphasis on vaccination, therapy-specific measures, and particularities of the Brazilian endemic infectious diseases' scenario.

Conclusion We propose a vaccination schedule, infectious screening routine, and prophylactic measures based on the current scientific evidence. Awareness of emergent tropical diseases is necessary due to evidence of demyelinating events and possible parainfectious cases of MS and NMOSD.
Serum Vitamin D Levels in Relation to Development of Multisystem Inflammatory Syndrome in Pediatric COVID-19
Authors: Zengin Neslihan , Bal Alkan , Goren Tugba Aysun , Bayturan Semra Sen , Alkan Fatos , Akcali Sinem
Published: October 2022

Objective The aim of the study is to evaluate vitamin D (vit D) levels in children with and without development of multisystem inflammatory syndrome in children (MIS-C) after coronavirus disease 2019 (COVID-19) and also between those with severe and moderate MIS-C.

Methods This comprises retrospective data of 68 patients including 34 patients with MIS-C and admitted into the pediatric intensive care unit (MIS-C group) and 34 patients without MIS-C (non-MIS-C group) were analyzed for their presenting characteristics, serum vit D levels, ventilatory needs, and prognostic scores.

Results Vit D levels were significantly lower in patients with versus without MIS-C [9 (2–18) vs. 19 (10–43) ng/mL, p <0.001], and also in patients with severe versus moderate MIS-C [7.5 (2–17) vs. 9 (5–18) ng/mL, p = 0.024]. Vit D deficiency (levels <12 ng/mL) was more common in the MIS-C versus non-MIS-C group (79.4 vs. 11.8%, p <0.001) and in severe versus moderate MIS-C (92.9 vs. 70.0%, p <0.001). The severe versus moderate MIS-C was associated with significantly higher levels of procalcitonin [7.6 (0.9–82) vs. 1.7 (0.2–42) ng/mL, p = 0.030] and troponin [211 (4.8–4,545) vs. 14.2 (2.4–3,065) ng/L, p = 0.008] and higher likelihood of reduced ejection fraction (75.0 vs. 15.4%, p = 0.004).

Conclusion Our findings indicate the higher prevalence of vit D deficiency in pediatric COVID-19 patients with versus without MIS-C, as well as in those with severe versus moderate MIS-C. Higher troponin and procalcitonin levels and dyspnea at presentation seem also to be risk factors for severe MIS-C, more pronounced cardiac dysfunction, and poorer prognosis.
Investigation of trapping effects in Schottky lightly doped P-GaN gate stack under γ-ray irradiation
Authors: Wang Peng , Jiang Yizhou , Gu Yitian , Huang Menglin , Huang Wei , Chen Shiyou , Xiao Zhiqiang , Zou Xinbo , Qiu Yiwu , Zhou Xinjie , Zhou Jianjun , Zhang David Wei
Published: October 2022

In this Letter, trapping effects of a Schottky lightly Mg-doped p-GaN gate stack for low-power applications have been investigated, and further analysis focusing on AlGaN/GaN interface traps under γ-ray irradiation has been carried out. A negligible shift in the flatband voltage with γ-ray irradiation dose up to 800 krad indicates the superior radiation tolerance of the p-GaN gate structure. The difference between capacitance dispersion at the measurement frequency below and above 500 kHz is observed, which is attributed to trapping effects in different locations with varying gate voltage. Moreover, the frequency-dependent conductance method is put forward to assess the effects of different doses of γ-ray irradiation on the AlGaN/GaN interface traps. Based on that method, aside from the shallow trap states [the trap activation energy (ET) is about 0.334–0.338 eV] previously found in the traditional normally on high electron mobility transistor (HEMT), another type of deeper trap states at the AlGaN/GaN interface (ET is about 0.467–0.485 eV) is detected. It is observed that the ET of shallow trap states distributes at a deeper and broader range as the irradiation dose increases. Additionally, the trap density decreased after 600 krad doses irradiation but increased after 800 krad doses irradiation for both deep and shallow ET. Transmission electron microscopy and atomic force microscopy are used to demonstrate the smooth AlGaN/GaN interface morphology, which will not be greatly damaged after 800 krad doses of γ-ray irradiation. This work can provide a further understanding of radiation tolerance and trapping effects of p-GaN gate HEMTs for low-voltage applications.
Misfit layered compounds: Unique, tunable heterostructured materials with untapped properties
Authors: Ng Nicholas , McQueen Tyrel M.
Published: October 2022

Building on discoveries in graphene and two-dimensional (2D) transition metal dichalcogenides, van der Waals (VdW) layered heterostructures—stacks of such 2D materials—are being extensively explored with resulting new discoveries of novel electronic and magnetic properties in the ultrathin limit. Here, we review a class of naturally occurring heterostructures—the so-called misfits—that combine disparate VdW layers with complex stacking. Exhibiting remarkable structural complexity and diversity of phenomena, misfits provide a platform on which to systematically explore the energetics and local bonding constraints of heterostructures and how they can be used to engineer novel quantum fabrics, electronic responsiveness, and magnetic phenomena. Like traditional classes of layered materials, they are often exfoliatable and thus also incorporatable as units in manually or robotically stacked heterostructures. Here, we review the known classes of misfit structures, the tools for their single crystal and thin film synthesis, the physical properties they exhibit, and the computational and characterization tools available to unravel their complexity. Directions for future research are also discussed.
X-ray imaging of the magnetic configuration of a three-dimensional artificial spin ice building block
Authors: Pip Petai , Treves Samuel , Massey Jamie R. , Finizio Simone , Luo Zhaochu , Hrabec Aleš , Scagnoli Valerio , Raabe Jörg , Philippe Laetitia , Heyderman Laura J. , Donnelly Claire
Published: October 2022

The extension of artificial spin systems to the third dimension offers advances in functionalities and opportunities for technological applications. One of the main challenges facing their realization is the fabrication of three-dimensional geometries with nanoscale resolution. In this work, we combine two-photon lithography with deformation-free pyrolysis and a GdCo coating to create a three-dimensional (3D) tripod structure that represents a building block of an 3D artificial spin ice, surrounded by a two-dimensional magnetic film. We map the three-dimensional magnetic configuration of the structure and its surroundings using soft x-ray magnetic laminography. In this way, we determine the magnetic configuration of the tripod nanostructure to be in the low-energy two-in-one-out spin ice state, observed at the 2D vertex of a kagome ice and predicted for three-dimensional vertices of magnetic buckyball structures. In contrast to isolated vertices, the degeneracy of this state can be lifted by the surrounding film, which also offers a route toward the controlled injection of emergent charges. This demonstration of the building block of a 3D spin system represents the first step toward the realization and understanding of more complex 3D artificial spin systems.
Details of the neutral energy distribution and ionization source using spectrally resolved Balmer-alpha measurements on DIII-D
Authors: Haskey S. R. , Grierson B. A. , Stagner L. , Chrystal C. , Bortolon A. , Laggner F. M.
Published: October 2022

Spectrally resolved passive Balmer-α (D-α, H-α) measurements from the DIII-D 16 channel edge main-ion charge exchange recombination system confirm the presence of higher energy neutrals (“thermal” neutrals) in addition to the cold neutrals that recycle off the walls in the edge region of DIII-D plasmas. Charge exchange between thermal ions and edge neutrals transfers energy and momentum between the populations giving rise to thermal neutrals with energies approximating the ions in the pedestal region. Multiple charge exchange events in succession allow an electron to effectively take a random walk, transferring from ion to ion, providing a pathway of increasing energy and velocity, permitting a neutral to get deeper into the plasma before a final ionization event that contributes to the ion and electron particle fueling. Spectrally resolved measurements provide information about the density and velocity distribution of these neutrals, which has been historically valuable for validating Monte Carlo neutral models, which include the multi stage charge exchange dynamics. Here, a multi-channel set of such measurements is used to specifically isolate the details of the thermal neutrals that are responsible for fueling inside the pedestal top. Being able to separate the thermal from the cold emission overcomes several challenges associated with optical filter-based neutral density measurements. The neutral dynamics, deeper fueling by the thermal neutrals, and spectral measurement are modeled with the FIDASIM Monte Carlo collisional radiative code, which also produces synthetic spectra with a shape that is in close agreement with the measurements. By scaling the number of neutrals in the simulation to match the intensity of the thermal emission, we show it is possible to obtain local neutral densities and ionization source rates.
A compact repetitive high energy-density accelerator HEART-20 based on propylene carbonate pulse forming line
Authors: Zhang Zicheng , Liu Shifei , Yang Hanwu , Li Diangeng , Fan Yuwei , Zhang Jiande
Published: October 2022

The development of pulsed power technology requires an electron beam accelerator with high output power and repetitive operation. A compact repetitive electron beam accelerator based on a pulse transformer and a pulse forming line of high permittivity liquid, as an essential type of one, has attracted extensive attention at the present time. In this paper, the development of a compact high energy-density electron beam accelerator, viz., HEART-20, based on a propylene carbonate (PC) forming line is presented. The accelerator HEART-20 consists of a primary energy source, a pulse transformer, a PC pulse forming line, a gas spark gap switch, and a vacuum diode. First, the operation principle of the accelerator is described. Second, the design of the accelerator’s parameters is presented. A pulse transformer is developed for rapid charging of the PC-filled pulse forming line. The coupling coefficient is above 0.9, the voltage ratio is about 200, and the operation voltage is about 800 kV. Third, the energy storage characteristics of PC are investigated. The insulation characteristics of PC under positive charging voltage are found to perform better than those under negative charging voltage. The insulating strength of PC can be improved by pressurization. Finally, the development of the accelerator HEART-20 is presented. Across a vacuum diode load, it can steadily operate at a 20 GW output power in 5 Hz rep-rate. Moreover, it can drive a magnetically insulated line oscillator to produce about 2.0 GW microwave. These findings provide a good foundation for the development of a rep-rate intensive electron beam accelerator with promising applications for the future.
Ion beam stopping power effects on nuclear fusion reactions
Authors: Zhang Yihang , Zhang Zhe , Zhu Baojun , Jiang Weiman , Zhang Xiaopeng , Zhao Xu , Yuan Xiaohui , Zhong Jiayong , He Shukai , Lu Feng , Wu Yuchi , Zhou Weimin , Zhang Faqiang , Zhou Kainan , Xie Na , Huang Zheng , Gu Yuqiu , Weng Suming , Xu Miaohua , Li Yingjun , Li Yutong
Published: October 2022

Fusion reactions in a plasma environment are fundamental issues with general interest in high energy density sciences. The reaction rate in an astro-system, which may differ from cold matter, is an important subject in the ambiguous problems of elemental abundance. In addition, the stopping of charged particle in plasma has a considerable impact on the design of nuclear fusion reactors as it is related to the α-particle heating process and ion-driven fast ignition, but still needs better understanding. In this research, an experiment on laser-driven D–D fusion reactions (D + D → 3He + n) has been carried out to investigate the effects of ion stopping power in plasma on fusion reactivities. The neutron yields, plasma density, and deuteron energy loss in the plasma have been measured simultaneously, and the plasma temperature has been analyzed from simulations. It is experimentally demonstrated that the fusion reaction yield is closely correlated with ion beam transportation in the plasma. As a cold target heated to plasma, the reaction probabilities from a deuteron beam and deuterated target interactions can be enhanced or suppressed, which is ascribed to the deuteron stopping power variation in the plasma. The results show the importance of considering the temperature adjusted ion stopping power to correctly model the fusion reaction yields. This work has an impact on understanding the fusion reactions in plasma environment, which is also likely to help achieve higher neutron yields.
Enhanced sampling using replica exchange with nonequilibrium switches: A case study on simple models
Authors: Badani Shaunak , Krishnan Marimuthu
Published: October 2022

Configurational sampling is central to characterize the equilibrium properties of complex molecular systems, but it remains a significant computational challenge. The conventional molecular dynamics (MD) simulations of limited duration often result in inadequate sampling and thus inaccurate equilibrium estimates. Replica exchange with nonequilibrium switches (RENS) is a collective variable-free computational technique to achieve extensive sampling from a sequence of equilibrium and nonequilibrium MD simulations without modifying the underlying potential energy surface of the system. Unlike the conventional replica exchange molecular dynamics (REMD) simulation, which demands a significant number of replicas for better accuracy, RENS employs nonequilibrium heating (forward) and cooling (reverse) work simulations prior to configurational swaps to improve the acceptance probability for replica exchange by using only a few replicas. Here, we have implemented the RENS algorithm on four model systems and examined its performance against the conventional MD and REMD simulations. The desired equilibrium distributions were generated by RENS for all the model systems, whereas REMD and MD simulations could not do so due to inadequate sampling on the same timescales. The calculated work distributions from RENS obeyed the expected nonequilibrium fluctuation theorem. The results indicate that the switching time of the nonequilibrium simulations can be systematically altered to optimize the acceptance probability and the reduced work of switching. The modular implementation of RENS algorithm not only enables us to readily extend it to multiple replicas but also paves the way for extension to larger molecular systems in the future.
High-performance electron mobility and photoabsorption in Bi2O2Se nanoribbons
Authors: Huang Xiaoyu , Niu Chun-Yao , Wang Aihua , Song Yuling , Jia Yu
Published: October 2022

Two-dimensional (2D) Bi2O2Se has attracted much attention as a promising candidate for electronic and optoelectronic applications. However, the transport and optical properties in Bi2O2Se nanoribbons (NRs) are not yet fully understood. In this work, by using first-principles calculations, the intrinsic carrier mobility (μ) and the optical absorption properties of Bi2O2Se NRs are investigated. In contrast to the dramatic deterioration of μ in graphene upon the formation of NRs, the magnitude of μ in Bi2O2Se NRs can reach up to 3600 cm2 V−1 s−1 at a width ranging from 3.3 to 4.5 nm, which is about ten times higher than its sheet counterpart. Such a high intrinsic electron mobility of Bi2O2Se NRs can be attributed to the weaker edge state perturbations due to external strain inherent in Bi2O2Se NRs. Moreover, in Bi2O2Se NRs, the optical absorption at the visible (2.4–3.1 eV) and ultraviolet (4.3 eV) region reaches 5%–10% and 19.2%, respectively. Furthermore, the optical absorption properties can be well tuned by the width of NRs. In addition, the relatively small stretching modulus ranging from 0.40 to 2.24 × 10−7 J/m and the moderate critical strain ranging from 0.04 to 0.14 guarantee its moderate flexibility and ductility. Our results indicate that width modulation provides a potential approach for improving the transport and optical properties of Bi2O2Se nanostructures.
Third-order less oscillatory and less diffusive compact stencil-based upwind schemes, and their applications to incompressible flows and free surface flows
Authors: Yokoi Kensuke
Published: October 2022

We propose novel third-order less oscillatory and less diffusive compact stencil-based upwind schemes for the approximation of the continuity equation. The proposed schemes are based on the constrained interpolation profile-conservative semi-Lagrangian schemes. An important feature of the proposed schemes is that the interpolation functions are constructed using only variables within one upwind cell (a cell average and two boundary values). Furthermore, the proposed schemes have third-order accuracy and are also less oscillatory, less diffusive, and fully conservative. The proposed schemes are validated through various benchmark problems and comparisons with experiments of two droplets collision/separation and droplet splashing. The numerical results have shown that the proposed schemes have third-order accuracy for smooth solution, and capture discontinuities and smooth solutions simultaneously without numerical oscillations. The proposed schemes can capture the secondary vorticity of lid-driven cavity flow of Re = 7500 with a Cartesian grid of 64 × 64. The numerical results of two droplets collision/separation of We = 40 show that the proposed schemes can reproduce droplets collision/separation with quite coarse grids. These numerical results of droplet splashing have demonstrated that proposed schemes can reduce numerical diffusions well against existing schemes and robust.
Nonlinear optical limiting property of the carboxyl-functionalized Ti3C2 MXene nanosheets
Authors: Li Yuren , Si Jinhai , Yan Lihe , Fan Zhaolin , Liang Zezhou , Hou Xun
Published: October 2022

Nonlinear optical limiting (OL) properties of carboxyl-functionalized Ti3C2 nanosheets (COOH-MXene) were studied using the nanosecond laser Z-scan technology. COOH-MXene showed excellent broadband OL properties with OL thresholds of 0.34 J/cm2 at 532 nm and 0.58 J/cm2 at 1064 nm, and the OL mechanism was mainly attributed to the reverse saturable absorption effect. Femtosecond time-resolved transient absorption measurements were used to clarify the ultrafast carrier dynamics in the OL process, and the results revealed that excited states absorption (ESA) in MXene was enhanced by introducing more carboxyl group terminations. When COOH-MXene was irradiated by laser pulses, excited electrons in the conduction band of MXene could transfer to the carboxyl groups and induce the ESA in the surface functional groups, resulting in the excellent OL property of COOH-MXene.
Analytic high-order energy derivatives for metal nanoparticle-mediated infrared and Raman scattering spectra within the framework of quantum mechanics/molecular mechanics model with induced charges and dipoles
Authors: Pei Zheng , Mao Yuezhi , Shao Yihan , Liang WanZhen
Published: October 2022

This work is devoted to deriving and implementing analytic second- and third-order energy derivatives with respect to the nuclear coordinates and external electric field within the framework of the hybrid quantum mechanics/molecular mechanics method with induced charges and dipoles (QM/DIM). Using these analytic energy derivatives, one can efficiently compute the harmonic vibrational frequencies, infrared (IR) and Raman scattering (RS) spectra of the molecule in the proximity of noble metal clusters/nanoparticles. The validity and accuracy of these analytic implementations are demonstrated by the comparison of results obtained by the finite-difference method and the analytic approaches and by the full QM and QM/DIM calculations. The complexes formed by pyridine and two sizes of gold clusters (Au18 and Au32) at varying intersystem distances of 3, 4, and 5 Å are used as the test systems, and Raman spectra of 4,4′-bipyridine in the proximity of Au2057 and Ag2057 metal nanoparticles (MNP) are calculated by the QM/DIM method and compared with experimental results as well. We find that the QM/DIM model can well reproduce the IR spectra obtained from full QM calculations for all the configurations, while although it properly enhances some of the vibrational modes, it artificially overestimates RS spectral intensities of several modes for the systems with very short intersystem distance. We show that this could be improved, however, by incorporating the hyperpolarizability of the gold metal cluster in the evaluation of RS intensities. Additionally, we address the potential impact of charge migration between the adsorbate and MNPs.
Rotational flux influenced cusp entrainment in a viscous pool
Authors: Panda Santosh Kumar , Rana Basanta Kumar
Published: October 2022

Evolution of entrained gaseous cusp in a viscous liquid pool caused by a fully immersed horizontal revolving circular drum is elucidated thoroughly. Finite volume-based open source Gerris is employed to carry out the numerical simulations. Length θs* and width (H*) of the cusp are characterized thoroughly by varying the strength of rotational flux (measured by the capillary number, Ca) and depth of immersion (submersion height to roller diameter ratio, h/D) of the spinning roller. Locus and travel rate of cusp tip are also elaborated from origination to attainment of steady state with the progress of time for different combinations of Ca and h/D. We have also reported the bubble ejection mechanism from the advancing end of the cusp after achieving macroscopic steady length. Bubbling frequency and volume accumulation of detached bubbles show strong dependency on Ca or h/D. Entrainment patterns are also observed by investigating the effect of gravitational pull (measured by employing the Archimedes number, Ar) and viscous drag (specified by using the Morton number, Mo). Correlations are developed to estimate the cusp width (H*) at different angular locations and steady length of gaseous cusp θs*, which show satisfactory agreement within ±6%. Finally, an analytical model is proposed to determine the cusp width by using the relevant influencing forces acting on the cusp. A satisfactory agreement is obtained between the analytical solutions and computational results.
Heat transfer and behavior of the Reynolds stress in Mach 6 boundary layer transition induced by first-mode oblique waves
Authors: Guo Peixu , Shi Fangcheng , Gao Zhenxun , Jiang Chongwen , Lee Chun-Hian , Wen Chihyung
Published: October 2022

This paper investigates a Mach 6 oblique breakdown via direct numerical simulation in conjunction with stability and quadrant analyses. Particular emphasis is placed on, first, the heat transfer and mean flow distortion in the near-wall and outer transitional boundary layer, and, second, the flow events that are responsible for the production of the Reynolds stress. The energy budget reveals that enhancement of viscous dissipation due to mean flow distortion dominates the heat transfer overshoot, while the dissipation due to fluctuations is lesser but not negligible. Downstream of the location of the peak mean heat flux, the wall temperature gradient (non-dimensionalized by the freestream temperature and local boundary layer thickness) varies little, owing to the occurrence of breakdown and the establishment of self-similarity. Renormalized by the boundary layer thickness, a new correlation of the Stanton number shows no overshoot or difference between the original overshoot region and the turbulent region, which indicates the possibility of similarity once breakdown has occurred. In the outer region, enhanced advective heat exchange strongly reshapes the mean temperature profile. Because of successive modal growth and nonlinear saturation, the contributions of the primary oblique mode, streak mode, and a superharmonic to the outer advective heat transfer are found to compete near the location of the peak heat flux. From the perspective of fluid motions, quadrant analysis highlights the evenly and broadly distributed joint probability density function (PDF) of the fluctuating velocities during transition, which results in overproduction of the Reynolds stress, while the PDF is concentrated around zero in the turbulent region. The flow event Q2 (ejection) overtakes Q4 (sweep) in the outer boundary layer of the transitional region, mainly owing to the primary mode, while the two events become attenuated and nearly achieve balance when transition is complete.
Performance of different input and dissipation packages in WAVEWATCH III model during tropical cyclones
Authors: Yang Hongbin , Shao Zhuxiao , Liang Bingchen , Wang Zhenlu , Lee Dongyoung
Published: October 2022

Ocean surface waves exposed to extreme weather conditions, such as tropical cyclones (TCs), are critical environmental forces acting on the coastal and offshore structures. Therefore, it is necessary to investigate the applicability of the third-generation wave model WAVEWATCH III for simulated waves in the China Seas, where TCs are frequent. This study compares different packages of wind input and wave dissipation (ST1, ST2, ST3, ST4, and ST6) during five TCs with significant wave heights (SWHs) and wave spectra in the Yellow Sea, East China Sea, and South China Sea. The results show that ST6 performs best in the simulation of the SWHs, presenting the only positive deviation, with a normalized mean bias of 1.76%. ST2 systematically underestimates the large SWHs due to insufficient wind input from the spectra. However, the suitability of the packages varies in different sea conditions. ST6 is preferred in extreme wave simulations during TCs, ST4 performs best under the weak influence of TCs, and ST2 has the best performance in calm sea conditions.
Density-driven exchange flow propagating over an array of densified obstacles
Authors: Wu Ching-Sen
Published: October 2022

The evolution of bottom-propagating gravity currents with the presence of an array of densified obstacles submerged in a channel is investigated using large-eddy simulations. Our attention is particularly focused on the flow transition of gravity currents over rough surfaces with extra resistance that provokes significant dissipative processes. Two geometric parameters of the roughness elements, namely, the submergence ratio of the obstacle D/H and the gap-spacing ratio λ/D between obstacles, govern their kinematic and dynamic effects on the propagation of gravity currents. Physically, D/H plays a significant role in the control of the current diversion, and λ/D regulates the flow pathway of gravity current propagation. The integrated measures show that two distinct flow morphologies are identified. For a low submergence ratio (D/H<0.15), an overtopping flow is formed in which the gravity current travels on the top of the array and undergoes an inconspicuous loss of buoyancy, subject to minimal vertical convective instability interacting with the underlying ambient fluid within the gap regions. For a sufficiently high submergence ratio (D/H≥0.15) and a certain gap spacing (2≤λ/D<4), an overrunning flow is formed in which the current rapidly decelerates to a buoyancy–inertia state and then transitions to a drag-dominated state with a gain in excessive drag, in which the front velocity is proportional to t−0.5. However, the simulation results show a turning point toward an increase in the gap spacing as λ/D≥4, that the maximum drag acting on the gravity current is measured when it impinges on the second obstacle of an array, and that the drag coefficient goes up by 10%–40%, depending on D/H. The propagation of the gravity current does not show a higher sensitivity to the retarding effect instead. Meanwhile, the promotion of energy conversion occurs because of the gravity current encountering the continuous climbing and plunging flow behavior between two adjacent obstacles in regular motions.