bluuebunny/crossref_metadata_2025 huggingface dataset:
Impact of baffle geometry on the fluid motion in the stirred vessel
Authors: Młynarczykowska Anna , Ferrari Simone , Demurtas Luana , Jaszczur Marek
Published: October 2022

The fluids mixing is a crucial operation in a large number of engineering systems. It has major significance in chemical engineering, food, cosmetics and pharmaceutics production, biotechnology, wastewater treatment engineering, and countless other applications. Among many available systems online mixing with static mixers and stirred tanks plays a primary role and has been developed to meet several processing objectives. The effectiveness of the mixing process depends on a number of parameters, i.e. impeller shape, mixing phases properties, process conditions as well as stirred vessel design - in particular, number and baffles’ design. The optimal baffles geometry is still an open issue and is usually design with trial and error methods. In this study, the focus is on the experimental investigations of the baffle geometry on the fluid flow and mixing phenomenon as well as on the required by the mixer power. In order to evaluate velocity field and mixing parameters, particle image velocimetry measurement is used whereas to obtain the power consumption by the stirred vessel precise torque meters were used. Measurements are carried out for different Reynolds numbers, to determine the most efficient process parameters. It has been shown that for the analyzed range of Reynolds numbers, the baffles design significantly influences fluid flow motion, mixing phenomena and the pumping number power number, but not affect the power number.
Stereo PIV measurement of diffuser swirling flow
Authors: Procházka Pavel , Uruba Václav , Štefan David , Rudolf Pavel
Published: October 2022

The swirling flow in a diffuser has been studied using the stereo PIV technique. The DANTEC hardware and software were used for the experiment. The water pipe flow in the diffuser inlet has been set spinning by introducing tangential jet flow. Both piping and diffuser were of circular cross-section, however diffuser casing had rectangular (square) cross-section. The plane of measurement was located perpendicular to the flow within the diffuser. The two cameras with the Scheinpflug lens mounting were used, however the angle between the lenses axes and the diffuser outer surface was far from to be perpendicular, as recommended in similar situations. This configuration has been dictated by technical conditions in the laboratory. The two-level calibration target with dots was used for the cameras calibration. The calibration covers the diffusers central region in a good quality, however regions close to the walls were not well resolved. Many combinations of axial and tangential inflow conditions have been studied. The acquisition covered about 3 seconds in real time with frequency 500 Hz. Both statistics and dynamics of the flow have been studied in details.

Results are shown for both statistical characteristics and dynamical analysis of various conditions. During experiments the air-glass-water interface was not normal to the camera viewing axis. The discussion how to solve this problem and of the bias of the calibration will be introduced.
Interactive flow around a circular cylinder controlled by a small rod
Authors: Tsutsui Takayuki
Published: October 2022

In this paper, a unique flow control method using a small rod, called the forced reattachment method, is proposed for the control of the flow around a bluff body. As described in previous papers, the forced reattachment method is a type of separated shear layer control that reduces drag and generates lift, and it can only occur under certain conditions. The forced reattachment phenomenon occurs as a result of an interactive flow between a circular cylinder and a small rod. This phenomenon is characterized by many special features, such as a large stagnant region behind the circular cylinder and the reattachment flow, which adheres to the rear face of the circular cylinder. It is also interesting how it reduces the total drag, including that of the small rod. The aim of this study was to elucidate the details of the stagnant region, the properties of the reattachment flow, and the reduction of the total drag.
Experimental Research on the Flow in the Steam Turbine Axial Exhaust Hood
Authors: Tupy David , Slama Vaclav , Kalista Robert
Published: October 2022

There is the still remaining task to increase the efficiency of power plants and steam turbines. One possibility to increase the thermodynamic efficiency is to apply a suitable exhaust hood. Axial exhaust hoods are mainly designed for small turbines up to 180 MW. They are a very important part of steam turbines and its main purpose is to take away the steam from the last stage outlet to a condenser with minimal loss or even with pressure compression and an increase in the last stage enthalpy drop. This paper concerns experimental measurements on the axial exhaust hood wind tunnel model. The main goal of this paper is to determine how given geometrical and flow parameters affect the resulting pressure recovery coefficient. Main observed parameters are velocity and circumferential angle profiles at the diffuser inlet along with a number, shape and geometrical configuration of internal struts. Several geometrical variants are measured for two types of circumferential angles at the diffuser inlet and for two values of Mach number in the presented work. Multi-hole pneumatic probes and pressure taps are used for flow parameters measurement. The proposed experimental model, along with corresponding CFD (computational fluid dynamics) simulations, will help to optimize the flow parameters in the exhaust hood and allow a decrease in pressure losses in this part.
On 3D structure of a circular cylinder wake
Authors: Uruba Václav , Procházka Pavel , Skála Vladislav
Published: October 2022

The 3D structure of the wake behind a circular cylinder in a cross-flow is studied experimentally using stereo PIV technique, Reynolds number was around 5 thousands. The statistical characteristics along the cylinder axis are effectively constant and thus 2D, however instantaneous flow-field in the wake is fully 3D. Within the wake dynamical flow, the streamwise vortices and spots of streamwise velocity component pulsations are detected.
Measurement of Pool Boiling Heat Transfer Coefficient with an Insulated Stainless-Steel Block
Authors: Vajc Viktor , Dostál Martin
Published: October 2022

We have designed an apparatus dedicated for measurement of heat transfer coeffcient during saturated nucleate pool boiling. After several performed measurements, we have applied three important modifications of the apparatus motivated by discrepancies between measured and correlated heat transfer coeffcients. Firstly, the cubic stainless-steel heated block of the apparatus no longer accommodates heating cartridges. It now stands on a copper carrier of the cartridges, which are vertically oriented. Secondly, we have insulated the heated block with plates made of cellular glass. Thirdly, thermocouples used for measurement of temperatures inside the block have been fixated with a special high-temperature adhesive. These modifications were applied in order to improve the temperature distribution inside the block and to eliminate the impact of surroundings on measured heat transfer coeffcients. This contribution presents and discusses experimental results obtained with these modifications.
On the possible origin of a vapour cone occurring during the transonic flight in moist air
Authors: Vestfálová Magda , Hála Jindřich , Šafařik Pavel , Šimurda David
Published: October 2022

In aerodynamics as in other sciences, there are some phenomena which are widely explained in a way that under a closer look turns out to be based on wrong assumptions and thus not very convincing. One of these is the effect referred to as vapour cone or shock collar which is the cloud of condensed water of the conical shape that forms around objects travelling at transonic speeds through the moist air. This paper aims to shed light on some basic principles that might stand behind this effect and based on the simple physical model provide possible explanation and correct some of the common misconceptions which are repeated ad nauseam not only on the internet sites of aerodynamics enthusiasts but also in some textbooks.
Behaviors and kinetics of non-isothermal gasification reaction of cokes with different reactivity
Authors: Yan Ruijun , Liu Zhenggen , Chu Mansheng , Liu Peijun
Published: October 2022

Due to the great difference of coke properties used in blast furnaces, how to reasonably evaluate coke has become a hotspot. In this study, the non-isothermal gasification behaviors and kinetics of cokes with different reactivity are studied, which provides theoretical basis for reasonable coke evaluation. The coke reactivity index of coke A, B and C are 24.75%, 30.80% and 41.25%, respectively. The FWO method is used to calculate the kinetic parameters. The results show that coke reactivity has little influence on gasification reaction starting temperature at lower heating rate. The starting temperature decrease gradually with coke reactivity at higher heating rate. Under the same conditions, the alkali index and microcrystalline structure of cokes can better characterize the coke reactivity. The gasification mechanism does not change with coke reactivity. The reaction is divided into two stages. In the early stage, the average apparent activation energy E of coke powder A, B and C are 211.52 kJ/mol, 214.96 kJ/mol 208.99 kJ/mol, respectively. The optimal mechanism models are all F model, in which the integral form is G(α) = (1–α)−1–1. In the later stage, the average E of coke powder A, B and C are 226.89 kJ/mol, 207.53 kJ/mol and 192.12 kJ/mol, respectively. The optimal models are all A1 model, in which the integral form is G(α) = –ln(1–α).
Und auf einmal ist es Herbst.
Authors: Börner Doris , Zohmann Andreas
Published: October 2022

Liebe Leserin, lieber Leser,

nach diesem ungewöhnlich heißen und trockenen Sommer
begrüßen sicherlich viele die jetzt kälteren und feuchteren
Tage. Die Zeit für Kastanien, Kürbissuppe, Kuscheldecke, Kerzen
– und zum Lesen!
Geschichte der Klinik für Dermatologie und Venerologie am Vivantes Klinikum Berlin-Neukölln
Authors: Buder Susanne , Hillen Uwe , Kohl Peter Karl
Published: October 2022

Die 95-jährige Geschichte der Hautklink Britz, später Hautklinik Neukölln, der ältesten der Vivantes-Dermatologien, wird mit ihren klinischen und wissenschaftlichen Schwerpunkten anhand der Wirkungszeiten der jeweiligen Leiter der Klinik im Kontext der zeitlichen Umstände, darunter der Nationalsozialismus, der 2. Weltkrieg, die Ökonomisierung der Medizin und das Auftreten der Sars-CoV-2-Pandemie dargestellt. Das Fachgebiet in seiner ganzen Breite zu vertreten und eine sorgfältige Weiterbildung für angehende Fachärzte zu ermöglichen war allen Chefärzten bis heute ein wichtiges Anliegen. Während über Jahrzehnte die Behandlung venerisch erkrankter Patienten die Klinik prägte, bilden heute Dermatochirurgie und Dermatoonkologie einschließlich medikamentöser Tumortherapie und die Versorgung schwerer Hauterkrankungen die Schwerpunkte des Klinikalltages. Die über Jahrzehnte kontinuierlich weiterentwickelte Venerologie und Dermatohistologie stellen bis heute besondere Merkmale des Hauses dar.
ASCO-Update zum nicht-kleinzelligen Lungenkarzinom
Authors: Schmale Ine
Published: October 2022

Die Behandlung des fortgeschrittenen nicht-kleinzelligen Lungenkarzinoms (NSCLC) bleibt trotz vieler Therapieoptionen eine Herausforderung. Insbesondere die Einordnung der verfügbaren Wirksubstanzen anhand der bekannten Studienergebnisse kann nicht ohne kritische Betrachtung erfolgen. Beim diesjährigen ASCO wurden in der „Oral Session“ Auswertungen zum Stellenwert von Immun- und Chemotherapie der FDA präsentiert und weitere zielgerichtete Strategien vorgestellt.
Digitalisierung der Medizin
Authors: Bubenzer Rainer H.
Published: October 2022

Zu den Brennpunkten in der Diskussion um die Digitalisierung der Medizin gehört der Datenschutz. Auch auf dem diesjährigen Kongress der Deutschen Gesellschaft für Innere Medizin (DGIM) in Wiesbaden nahm dieses Thema breiten Raum ein, insbesondere die Frage, ob ein überzogener Datenschutz in Deutschland eine Ursache für das im weltweiten Vergleich kaum ausgeschöpfte Potenzial der Digitalisierung ist.
Allgemeine Palliativversorgung im Krankenhaus während der ersten Welle der COVID-19-Pandemie
Authors: Werner Liane , Fischer Marius , van Oorschot Birgitt , Ziegaus Anke , Schwartz Jacqueline , Reuters Marie-Christine , Schallenburger Manuela , Henking Tanja , Neuderth Silke , Simon Steffen , Bausewein Claudia , Roch Carmen , Neukirchen Martin ,   für die PallPan-Forschungsgruppe
Published: October 2022

Einleitung Im Forschungsverbund deutscher universitärer Palliativzentren (PallPan) im Netzwerk Universitätsmedizin (NUM) wurden Handlungsempfehlungen für die Versorgung von Schwerkranken und Sterbenden in Pandemiezeiten erarbeitet. Dazu wurden auch die Erfahrungen und Bedürfnisse von patientennah tätigen Mitarbeitenden im Krankenhaus außerhalb von spezialisierten Palliativstationen während der 1. Welle der COVID-19-Pandemie untersucht.

Methode Bundesweite Online-Befragung von 8882 akutstationär tätigen Ärzt*innen, Pflegenden und Therapeut*innen im Zeitraum von Dezember 2020 bis Januar 2021 mittels eines neu entwickelten und pilotierten Fragebogens zu Veränderungen, Belastungen und zur Zusammenarbeit mit der spezialisierten Palliativmedizin. Gruppenbildung anhand der Veränderungen der Anzahl von Schwerkranken und Sterbenden in der ersten Welle der Pandemie. Aufgrund des explorativen Charakters der Studie wurden die Daten deskriptiv analysiert.

Ergebnisse 505/8882 vollständig bearbeitete Fragebögen wurden ausgewertet (5,7 %). 167/505 (33,1 %) der Befragten berichteten über eine verschlechterte Versorgungsqualität von Schwerkranken und Sterbenden. 464/505 (91,8 %) berichteten über Ausnahmeregelungen für Besuche von Sterbenden. Der meistgenannte Belastungsfaktor war die wahrgenommene Vereinsamung der Schwerkranken und Sterbenden 437/505 (86,5 %), gefolgt von den verschärften Hygieneregeln 409/505 (81 %), der erhöhten Arbeitsbelastung 372/505 (73,3 %) und der wahrgenommenen psychischen Belastung von Angehörigen und Hinterbliebenen 395/505 (78,2 %). Tablet-PCs zur Unterstützung der Patienten-Angehörigen-Kommunikation wurden von 141/505 (27,9 %) der Befragten genutzt. 310/505 (61,4 %) des in die Patientenversorgung involvierten palliativmedizinischen Fachpersonals und 356/505 (70,5 %) der Befragten hielten weitere palliativmedizinische Angebote für hilfreich.

Folgerung Die Erfahrungen und Vorschläge zur Verbesserung der Palliativversorgung in Pandemiezeiten sind in die PallPan-Handlungsempfehlungen integriert. Angehörigenbesuche sollten ermöglicht und um digitale Angebote erweitert werden. Palliativversorgung sollte in Pandemie- und Krisenpläne integriert werden.
Auswirkungen der SARS-CoV-2-Pandemie auf die Inanspruchnahme der
onkologischen Rehabilitation: eine
Difference-in-Differences-Analyse
Authors: Fauser David , Banaschak Hannes , Zollmann Pia , Streibelt Marco , Bethge Matthias
Published: October 2022

Ziel der Studie Der durch die SARS-CoV-2-Pandemie eingeschränkte
Zugang zur rehabilitativen Versorgung kann die Teilhabe von Menschen mit
Krebserkrankungen beeinträchtigen und birgt die Gefahr einer Progression
der zugrundeliegenden Erkrankung. Ziel unserer Analysen war es zu beschreiben,
in welchem Umfang die Inanspruchnahme onkologischer Rehabilitation
pandemiebedingt zurückgegangen ist.

Methodik Wir nutzten monatliche Querschnittsdaten von der Deutschen
Rentenversicherung zur Inanspruchnahme onkologischer Rehabilitation
(Ca-Reha-Leistung nach § 15 für Versicherte im
erwerbsfähigen Alter oder § 31 Abs. 1 Nr. 2 SGB VI für
Rentner) in den Jahren 2019 und 2020. Mit einem Difference-in-Differences-Modell
schätzten wir die auf die Pandemie zurückzuführende
Reduktion der Inanspruchnahme onkologischer Rehabilitation. Als
Difference-in-Differences-Schätzer wurde das Incidence Rate Ratio (IRR)
berechnet.

Ergebnisse Wir berücksichtigten 146.924 onkologische
Rehabilitationen im Jahr 2019 und 113.117 Leistungen im Jahr 2020. Die
Inanspruchnahme onkologischer Rehabilitation reduzierte sich pandemiebedingt um
11,5% bei Leistungen nach § 15 SGB VI (IRR=0,885;
95% KI: 0,864 bis 0,906) und um 26,5% bei Leistungen nach
§ 31 (IRR=0,735; 95% KI: 0,717 bis 0,754). Bei
Ca-Reha-Leistungen nach § 31 war der Rückgang in den alten
Bundesländern höher als in den neuen Bundesländern und
für allgemeine Antragsverfahren deutlich stärker als für
Anschlussrehabilitationen.

Schlussfolgerung Die Analysen zeigen einen pandemiebedingten
Rückgang onkologischer Rehabilitation vor allem bei onkologischen
Rehabilitationsleistungen für Rentner nach § 31. Der Verzicht
auf die durch medizinische Rehabilitation erreichbare körperliche und
psychische Erholung und Linderung von Krankheits- und Behandlungsnebenwirkungen
wird für viele an Krebs erkrankte Personen mit einer
Verschärfung von Teilhabeeinschränkungen einhergehen. Ein
wiederholtes Monitoring von Arbeitsfähigkeit und Gesundheit chronisch
kranker Menschen könnte erforderliche Daten generieren, um zu
klären, warum rehabilitationsbedürftige Menschen von der
Inanspruchnahme onkologischer Rehabilitation Abstand genommen haben und wie sie
unterstützt werden können.
Post-COVID: Alles eine Frage der Definition?
Authors: Lemhöfer Christina , Appel Katharina S. , Häuser Winfried , Hettich Nora , Kohls Mirjam , Polidori Maria Cristina
Published: October 2022

Die Prävalenz des Post-COVID-Syndroms (PCS) ist noch nicht abschließend geklärt. Die bisherigen Definitionen bilden vorrangig zeitliche Aspekte ab, lassen jedoch funktionelle Defizite sowie die Objektivierung von Symptomen außer Acht. Dies führt zu diagnostischen sowie therapeutischen Unklarheiten. In Pubmed wurde daher nach systematischen Reviews gesucht, die sich mit den Folgen einer SARS-CoV-2-Infektion befassten. Die zugrunde liegenden Definitionen sowie zeitlichen Einschlusskriterien wurden extrahiert. 16 systematische Reviews wurden eingeschlossen, davon 11 mit einer Definition des PCS. In 58 % der analysierten Einzelstudien wurden Patienten mit einer Symptomatik > 12 Wochen und damit entsprechend der Definition des PCS inkludiert. Fazit: Eine weitere Präzisierung der Definition des PCS ist notwendig, um Diagnostik und eine multimodale Behandlung zu erleichtern und die knappen therapeutischen Ressourcen entsprechend zu nutzen.
Azidation with Hypervalent Iodine Reagents
Authors: Waser Jerome , Simonet-Davin Raphaël
Published: October 2022

In this short review, we describe applications of hypervalent iodine reagents for the azidation of organic compounds from seminal publications to the most recent reports. After reviewing selected examples of azidations based on the use of in situ formed unstable non-cyclic reagents, we focus in more detail on stable cyclic hypervalent iodine reagents. Important advances in the azidation of C–H bonds, alkenes, as well as other transformations are described. Rather than being comprehensive, we highlight selected key reports that, in our opinion, especially contributed to the advancement of research in the field.

1 Introduction

2 Non-Cyclic λ3-Iodanes

3 Heterocyclic λ3-Iodanes

3.1 Azidation of Aliphatic C–H Bonds

3.2 Azidation of Alkenes

3.3 Other Azidations

4 Conclusion and Outlook
Enantio- and Diastereoselective Assembly of Multi-Layer Folding Chiral Targets via Asymmetric Catalytic Single C–C Bond Formation
Authors: Li Guigen , Liu Yangxue , Rouh Hossein , Tang Yao , Wu Guanzhao , Yuan Qingkai , Zhang Sai , Wang Jia-Yin , Jin Shengzhou , Xu Ting , Wang Yu , Pan Junyi , Unruh Daniel
Published: October 2022

This work presents the first enantio- and diastereoselective assembly of multi-layer folding targets through asymmetric catalytic C–C bond formation. Pd[(S)-BINAP]Cl2 is found to be an efficient catalyst for the Suzuki–Miyaura coupling between phosphinyl bromides and benzothiadiazole boronic esters for this asymmetric assembly. The structure of the resulting chiral multi-layer folding framework is unambiguously determined by X-ray analysis and shows a nearly parallel pattern of three layers and quasi-syn and -anti configurations. Good to excellent diastereo- and enantioselectivities (up to >20:1 dr and >99:1 er) are achieved.
Chiral Proton-Transfer Shuttle Catalysts Promoted Enantio­selective Nazarov Cyclization
Authors: Zhu Shou-Fei , Cao Jin
Published: October 2022

The Nazarov cyclization reaction is a convenient, widely used method for the synthesis of cyclopentenones. In this account, we reviewed our recent efforts on the chiral proton-transfer shuttle catalysts promoted enantioselective Nazarov cyclization. We have synthesized various chiral cyclopenta[b]indoles and chiral α,α′-disubstituted cyclopentenones by means of cooperative catalysis of a Lewis acid and a chiral spiro phosphoric acid. The mechanistic studies revealed that the chiral spiro phosphoric acid acts as a multifunctional catalyst: it co-catalyzes the cyclization of the dienone and enantioselectively catalyzes a proton-transfer reaction of the enol intermediate via a hydrogen-­bonding network.

1 Introduction

2 Enantioselective Nazarov Cyclization of Indole Enones

3 Enantioselective Silicon-Directed Nazarov Cyclization

4 Conclusion
Photoredox Trifluoromethylation/Cyclization of N-Arylacrylamides with 4-(Difluoroamino)-1-[(trifluoromethyl)sulfonyl]pyridinium Triflate (TFSP)
Authors: Li Xiaoqing , Xu Xiangsheng , Sun Zetian , Yang Hui , Chen Huimin , Mao Fenghua
Published: October 2022

A photoredox trifluoromethylation/cyclization of N-arylacrylamides with inexpensive stable solid 4-(difluoroamino)-1-[(trifluoromethyl)sulfonyl]pyridinium triflate (TFSP) has been developed.
Calibrating instruments to analyze energetic neutral atoms in space
Authors: Piccone Ashley
Published: October 2022

Neutrals are unaffected by electromagnetic fields in space, providing important information about their sources, but are difficult to characterize at low energies.
Reducing energy barriers by multi-interface design on MXene with confined Fe-doped CoSe2 for ultra-efficient OER electrocatalysis
Authors: Yuan Yuxi , Lian You , Yu Ting , Qu Yaohui , Yuan Cailei , Guo Manman
Published: October 2022

To design multi-heterointerfaces for doping-type electrocatalysts is a promising strategy to synergistically balance the catalytic activity/durability. In this study, we report a dual-MOFs/MXene composite derivation strategy to construct porous N-doped carbon encapsulating Fe-doped CoSe2 on both sides of MXene (Fe-CoSe2@PNC/TC). Combining multi-characterizations and density functional theory calculations, the Fe doping and well-designed multi-interfaces can induce the internal Se vacancy and electronic structure modulation, increasing and enhancing the active sites and, thus, reducing energy barriers for oxygen evolution reaction (OER). Thereby, the OER activities of Fe-CoSe2@PNC/TC powder materials have been significantly improved, which exhibits an overpotential of only 244 mV to attain 10 mA cm−2 with the long-term durability and a ultra-small Tafel slope of 41.1 mV dec−1 in 1.0 M KOH electrolyte (No IR correction), far outperforming the benchmark of commercial IrO2. This work proposes a controllable route combining multi-interface design and heteroatom doping for ultra-efficient OER electrocatalysis.
First divertor Thomson scattering measurements on MAST-U
Authors: Clark J. G. , Bowden M. D. , Kim Y. , Parry B. , Rose E. , Sarwar R. , Scannell R.
Published: October 2022

MAST-U is equipped with a Super-X divertor, which aims to reduce heat flux to the target and promote detachment. Measurements of plasma electron density and temperature in the Super-X chamber offer insight into the processes at work in this type of divertor. First data have been obtained from the MAST-U divertor Thomson scattering diagnostic designed to measure these quantities. Following a Raman scattering calibration in nitrogen, the diagnostic operated over a number of plasma pulses in the first physics campaign. Electron density and temperature measurements have been taken in attached and detached conditions as the strike leg moved through the field of view of the diagnostic. The system operated with a dedicated 30 Hz laser with timing synchronized to seven similar lasers installed in the core Thomson system. Electron densities in the range of 1 × 1018–5 × 1019 m−3 have been measured by the system throughout these regimes. Although the system was specified to measure from 1 to 40 eV, electron temperatures in the Super-X divertor in the first campaign were low, and measurement down to 0.5 eV has been critical, particularly close to the detachment front. This generation of polychromator has been designed with increased stray light rejection compared to those used in the core system. This has proved successful with very low levels of stray light observed.
In situ MOCVD growth and band offsets of Al2O3 dielectric on β-Ga2O3 and β-(AlxGa1−x)2O3 thin films
Authors: Bhuiyan A F M Anhar Uddin , Meng Lingyu , Huang Hsien-Lien , Hwang Jinwoo , Zhao Hongping
Published: October 2022

The in situ metalorganic chemical vapor deposition (MOCVD) growth of Al2O3 dielectrics on β-Ga2O3 and β-(AlxGa1−x)2O3 films is investigated as a function of crystal orientations and Al compositions of β-(AlxGa1−x)2O3 films. The interface and film qualities of Al2O3 dielectrics are evaluated by high-resolution x-ray diffraction and scanning transmission electron microscopy imaging, which indicate the growth of high-quality amorphous Al2O3 dielectrics with abrupt interfaces on (010), (100), and (2¯01) oriented β-(AlxGa1−x)2O3 films. The surface stoichiometries of Al2O3 deposited on all orientations of β-(AlxGa1−x)2O3 are found to be well maintained with a bandgap energy of 6.91 eV as evaluated by high-resolution x-ray photoelectron spectroscopy, which is consistent with the atomic layer deposited (ALD) Al2O3 dielectrics. The evolution of band offsets at both in situ MOCVD and ex situ ALD deposited Al2O3/β-(AlxGa1−x)2O3 is determined as a function of Al composition, indicating the influence of the deposition method, orientation, and Al composition of β-(AlxGa1−x)2O3 films on resulting band alignments. Type II band alignments are determined at the MOCVD grown Al2O3/β-(AlxGa1−x)2O3 interfaces for the (010) and (100) orientations, whereas type I band alignments with relatively low conduction band offsets are observed along the (2¯01) orientation. The results from this study on MOCVD growth and band offsets of amorphous Al2O3 deposited on differently oriented β-Ga2O3 and β-(AlxGa1−x)2O3 films will potentially contribute to the design and fabrication of future high-performance β-Ga2O3 and β-(AlxGa1−x)2O3 based transistors using MOCVD in situ deposited Al2O3 as a gate dielectric.
Verification of ideal dense matter equation of state by molecular dynamics simulation
Authors: Li Yang , Xue Ti-Wei , Su Chuan-Jin , Guo Zeng-Yuan
Published: October 2022

Equation of state (EOS) of dense matter has a wide application in geophysics, astrophysics, and physical detonation. However, it is difficult to obtain simple and accurate EOS under ultrahigh-density conditions due to the complex matter structures. Recently, an ideal dense matter EOS based on thermodynamic symmetry has been proposed for ultrahigh-density matter, which is symmetric to ideal gas EOS. Here, owing to experimental limitations, molecular dynamics (MD) is performed to verify the EOS. First, we discuss the feasibility of a thermodynamic integration algorithm for implementing an isentropic process at ultrahigh density. Second, by analogy with heat capacity, we clarify that work capacity reflects the ability of matter to do work. Theoretical analysis shows that internal energy and work capacity of ideal dense matter are independent of temperature. Furthermore, MD simulations demonstrate that the effect of temperature on internal energy and work capacity weakens with increasing density, which conforms to the inference of ideal dense matter EOS. Finally, by simulating isentropic, isothermal, isobaric, and isochoric processes, it is found that the accuracy of ideal dense matter EOS in describing thermodynamic properties is positively related to the density. It is another perspective for the understanding of dense matter and ultrahigh-density EOS.
Topological valley crystals in a photonic Su–Schrieffer–Heeger (SSH) variant
Authors: Yu Z. , Lin H. , Zhou R. , Li Z. , Mao Z. , Peng K. , Liu Y. , Shi X.
Published: October 2022

Progress on two-dimensional materials has shown that valleys, as energy extrema in a hexagonal first Brillouin zone, provide a new degree of freedom for information manipulation. Then, valley Hall topological insulators supporting such-polarized edge states on boundaries were set up accordingly. In this paper, a two-dimensional valley crystal composed of six tunable dielectric triangular pillars in each unit cell is proposed in the photonic sense of a deformed Su–Schrieffer–Heeger model. We reveal the vortex nature of valley states and establish the selection rules for valley-polarized states. Based on the valley topology, a rhombus-shaped beam splitter waveguide is designed to verify the valley-chirality selection rule above. Our numerical results entail that this topologically protected edge states still maintain robust transmission at sharp corners, thus providing a feasible idea for valley photonic devices in the THz regime.
Analysis of mode excitation of a relativistic magnetron with azimuthal-periodic-cavity extraction
Authors: Shi Di-Fu , Qian Bao-Liang , Liu Ze-Yang , Fan Yu-Wei
Published: October 2022

Relativistic magnetron (RM) with all cavity-magnetron axial extraction (ACMAE) has attracted much attention, benefiting from its good performance. In this paper, RM with ACMAE is generalized to a general case called RM with azimuthal-periodic-cavity extraction due to the introduction of two structure parameters of R and S, where R indicates the number of cavities between the two extraction cavities in a coupling waveguide and S indicates the number of cavities between two adjacent coupling waveguides. The necessary conditions for mode excitation of the RM are theoretically investigated and verified by simulations. Using the expression of the necessary conditions, one can easily figure out the output mode components of the RM in theory according to the structural parameters and the number of electron spokes. This new technique provides more solving schemes with different extraction structures for designing high performance RMs with different advantages in applications of high power microwave.
Fast evaluation of the critical current of high-temperature superconducting coils based on the integral method
Authors: Zhong Junlin , Zou Shengnan , Lai Lingfeng , Chen Pengrong , Deng Shutong
Published: October 2022

The need for energy is growing as civilization develops. Superconductors have various benefits over regular conductors, including a high current-carrying density and nearly no resistance. Therefore, the objective that scientists continue to seek is the use of superconductors to replace traditional conductors in order to satisfy the demand for energy. As a key part of the superconducting electrical system, the critical current is one of the key properties of high-temperature superconducting (HTS) coils. Scholars have created a variety of numerical simulation models to estimate the performance of HTS coils. However, the extremely nonlinear E–J power law relationship that characterizes the voltage–current relationship in superconducting materials necessitates numerous iterative refinements during the coil design stage, which is time-consuming from the perspective of computing efficiency. Consequently, it is essential to increase computational efficiency. In this study, the critical current of HTS coils was calculated using the J model (integral method with the current density J as the state solution variable), and it was proved to be an efficient research method. The accuracy of the method is verified by comparing with the H model and the experimental measurement results of the critical current of the HTS coil. Moreover, compared with the reference finite element simulation model, this model has a speed advantage of at least four times, which is a good choice, especially, for HTS circular coils with large turns.
All-electrical valley filtering in graphene systems. I. A path to integrated electro-valleytronics
Authors: Chen Feng-Wu , Lue Ning-Yuan , Chou Mei-Yin , Wu Yu-Shu G.
Published: October 2022

Probing and controlling the valley degree of freedom in graphene systems by transport measurements has been a major challenge to fully exploit the unique properties of this two-dimensional material. In this theoretical work, we show that this goal can be achieved by a quantum-wire geometry made of gapped graphene that acts as a valley filter with the following favorable features: (i) all electrical gate control, (ii) electrically switchable valley polarity, (iii) robustness against configuration fluctuation, and (iv) potential for room temperature operation. This valley filtering is accomplished by a combination of gap opening in either bilayer graphene with a vertical electrical field or single layer graphene on h-BN, valley splitting with a horizontal electric field, and intervalley mixing by defect scattering. In addition to functioning as a building block for valleytronics, the proposed configuration makes it possible to convert signals between electrical and valleytronic forms, thus allowing for the integration of electronic and valleytronic components for the realization of electro-valleytronics.
Neurosynaptic-like behavior of Ce-doped BaTiO3 ferroelectric thin film diodes for visual recognition applications
Authors: Ye Fan , Tang Xin-Gui , Chen Jia-Ying , Zhong Wen-Min , Zhang Li , Jiang Yan-Ping , Liu Qiu-Xiang
Published: October 2022

Brain-like neuromorphic computing networks based on the human brain information processing model are gradually breaking down the memory barriers caused by traditional computing frameworks. The brain-like neural system consists of electronic synapses and neurons. The multiple ferroelectric polarization switching modulated by the external electric field is well suited to simulate artificial neural synaptic weights. Therefore, ferroelectric diodes' (FDs) synapses have great advantages in building highly reliable and energy-efficient artificial neural networks. In this paper, we demonstrate the FDs synapse, which is based on rare-earth metal-doped BaTiO3 ferroelectric dielectric layer materials. This performs short-term and long-term synaptic plasticity behaviors by modulating synaptic weights using pulsed stimuli to polarize or flip ferroelectric films. In addition, convolutional neural networks were constructed on the MNIST dataset and the Fashion-MNIST dataset to check the feasibility of the device in simulating bio-visual recognition. The results expand the application of FDs' devices in the intersection of artificial intelligence and bioscience.
Lensless polarization camera for single-shot full-Stokes imaging
Authors: Baek Nakkyu , Lee Yujin , Kim Taeyoung , Jung Jaewoo , Lee Seung Ah
Published: October 2022

Lensless cameras have recently emerged as a compact imaging system based on computational imaging with various multiplexing capabilities. Here, we propose a compact, low-cost, lensless camera that enables snapshot full-Stokes polarization imaging. While polarization imaging provides additional contrast based on the birefringence and surface properties of the object, most polarization cameras require bulky hardware or are limited to measuring only the linear polarization information. Our device, composed of a phase mask, a polarization-encoded aperture, and a regular image sensor, performs compressed imaging to recover linear as well as circular polarization information of the scene from single image capture. We demonstrate the full-Stokes imaging capabilities of our device and describe the image reconstruction and calibration processes.
Apparent line tension induced by surface-active impurities
Authors: Staniscia Fabio , Kanduč Matej
Published: October 2022

Line tension in wetting processes is of high scientific and technological relevance, but its understanding remains vague, mainly because it is difficult to determine. A widely used method to extract line tension relies on the variation of a droplet’s contact angle with the droplet’s size. Such an approach yields the apparent line tension, which is an effective parameter that factors in numerous contributions to the finite-size dependence, thus masking the actual line tension in terms of the excess free energy of the three-phase contact line. Based on our recent computer simulation study, we investigate how small amounts of nonionic surfactants, such as surface-active impurities, contribute to the apparent line tension in aqueous droplets. When depositing polydisperse droplets, their different surface area-to-volume ratios can result in different final bulk concentrations of surfactants, different excess adsorptions to the interfaces, and, consequently, different contact angles. We show that already trace amounts of longer-chained surfactants in a pre-contaminated liquid are enough to affect measurements of the apparent line tension. Our analysis quantifies to what extent “background” impurities, inevitably present in all kinds of experimental settings, limit the resolution of line tension measurements, which is crucial for avoiding data misinterpretation.
The parallel-transported (quasi)-diabatic basis
Authors: Littlejohn Robert , Rawlinson Jonathan , Subotnik Joseph
Published: October 2022

This article concerns the use of parallel transport to create a diabatic basis. The advantages of the parallel-transported basis include the facility with which Taylor series expansions can be carried out in the neighborhood of a point or a manifold such as a seam (the locus of degeneracies of the electronic Hamiltonian), and the close relationship between the derivative couplings and the curvature in this basis. These are important for analytic treatments of the nuclear Schrödinger equation in the neighborhood of degeneracies. The parallel-transported basis bears a close relationship to the singular-value basis; in this article, both are expanded in power series about a reference point and are shown to agree through second order but not beyond. Taylor series expansions are effected through the projection operator, whose expansion does not involve energy denominators or any type of singularity and in terms of which both the singular-value basis and the parallel-transported basis can be expressed. The parallel-transported basis is a version of Poincaré gauge, well known in electromagnetism, which provides a relationship between the derivative couplings and the curvature and which, along with a formula due to Mead, affords an efficient method for calculating Taylor series of the basis states and the derivative couplings. The case in which fine structure effects are included in the electronic Hamiltonian is covered.
Themes and patterns in print media coverage of wildfires in the USA, Canada and Australia: 1986–2016
Authors: Sachdeva Sonya , McCaffrey Sarah
Published: October 2022

Background Media wildfire coverage can shape public knowledge on fire-related issues, and potentially influence management decisions, so understanding the content of its coverage is important. Previous research examining media wildfire coverage has primarily focused on either a single fire or issue, and provides little insight about the range of wildfire-related topics discussed in the media. Aims We aimed to assess wildfire topics covered in print media between 1986 and 2016 across the USA, Canada and Australia. Methods Machine learning-based automated content analyses were conducted to identify primary topics within news articles and to map relationships between topics. Key results News articles related to wildfire were clustered into four topic areas: Fire Response, Management, Environmental Conditions and Property Preparedness. Notable between-country differences emerge: the US media coverage focuses most on firefighting; Canadian coverage, climate change; and Australian coverage, preparedness. Conclusions Our results reveal that: (1) wildfire media coverage has increased over the past 30 years; (2) coverage is more varied than the common perspective, i.e. media continues to portray fires in a negative light; and (3) topic coverage varies significantly between countries. Implications These findings can help identify gaps in media coverage, and provide insights into critical topics, or relationships between topics, that may need additional emphasis in conversations about how to better learn to live with fire.
Observations on populations of a small insectivorous bird,
Authors: Maute Kimberly , Story Paul , Hose Grant C , Warden Andrew , Dojchinov Greg , French Kristine
Published: October 2022

The use of chemical pesticides to manage locust populations in natural ecosystems is likely to impact non-target arthropods and their predators. However, the relative effects of different locust control applications on Australian birds are unknown. Aerial applications of fipronil and fenitrothion are examples of two pesticides used in locust control in semiarid Australia. To test the relative impacts of pesticides on non-target fauna, pesticides were applied to replicate sites using aerial ultra-low-volume application methods. The body condition and biomarkers of pesticide exposure in resident white-winged fairy wrens (Malurus leucopterus leuconotus) at treatment and control sites were measured for two weeks before and after treatments. No measures suggested negative impacts of pesticide applications. However, birds monitored at treatment sites gained mass, possibly due to indirect impacts of pesticides on bird feeding patterns or the availability or behaviour of insect prey. Bird mass measures remained high at fipronil sites, whereas the mass of birds at fenitrothion sites returned to baseline levels within one week. As this study was conducted during dry conditions, when locust plagues are less likely, future insecticide research should also consider the availability of insect prey, its effect on insectivore feeding behaviour and the interaction of rainfall events.
Decadal migration phenology of a long-lived Arctic icon keeps pace with climate change
Authors: Shuert Courtney R. , Marcoux Marianne , Hussey Nigel E. , Heide-Jørgensen Mads Peter , Dietz Rune , Auger-Méthé Marie
Published: October 2022

Animals migrate in response to seasonal environments, to reproduce, to benefit from resource pulses, or to avoid fluctuating hazards. Although climate change is predicted to modify migration, only a few studies to date have demonstrated phenological shifts in marine mammals. In the Arctic, marine mammals are considered among the most sensitive to ongoing climate change due to their narrow habitat preferences and long life spans. Longevity may prove an obstacle for species to evolutionarily respond. For species that exhibit high site fidelity and strong associations with migration routes, adjusting the timing of migration is one of the few recourses available to respond to a changing climate. Here, we demonstrate evidence of significant delays in the timing of narwhal autumn migrations with satellite tracking data spanning 21 y from the Canadian Arctic. Measures of migration phenology varied annually and were explained by sex and climate drivers associated with ice conditions, suggesting that narwhals are adopting strategic migration tactics. Male narwhals were found to lead the migration out of the summering areas, while females, potentially with dependent young, departed later. Narwhals are remaining longer in their summer areas at a rate of 10 d per decade, a similar rate to that observed for climate-driven sea ice loss across the region. The consequences of altered space use and timing have yet to be evaluated but will expose individuals to increasing natural changes and anthropogenic activities on the summering areas.
Recurrent Hippocampo-neocortical sleep-state divergence in humans
Authors: Jang Rockelle S. , Ciliberti Davide , Mankin Emily A. , Poe Gina R.
Published: October 2022

Sleep is assumed to be a unitary, global state in humans and most other animals that is coordinated by executive centers in the brain stem, hypothalamus, and basal forebrain. However, the common observation of unihemispheric sleep in birds and marine mammals, as well as the recently discovered nonpathological regional sleep in rodents, calls into question whether the whole human brain might also typically exhibit different states between brain areas at the same time. We analyzed sleep states independently from simultaneously recorded hippocampal depth electrodes and cortical scalp electrodes in eight human subjects who were implanted with depth electrodes for pharmacologically intractable epilepsy evaluation. We found that the neocortex and hippocampus could be in nonsimultaneous states, on average, one-third of the night and that the hippocampus often led in asynchronous state transitions. Nonsimultaneous bout lengths varied from 30 s to over 30 min. These results call into question the conclusions of studies, across phylogeny, that measure only surface cortical state but seek to assess the functions and drivers of sleep states throughout the brain.
Shaping overnight consolidation via slow-oscillation closed-loop targeted memory reactivation
Authors: Ngo Hong-Viet V. , Staresina Bernhard P.
Published: October 2022

Sleep constitutes a privileged state for new memories to reactivate and consolidate. Previous work has demonstrated that consolidation can be bolstered experimentally either via delivery of reminder cues (targeted memory reactivation [TMR]) or via noninvasive brain stimulation geared toward enhancing endogenous sleep rhythms. Here, we combined both approaches, controlling the timing of TMR cues with respect to ongoing slow-oscillation (SO) phases. Prior to sleep, participants learned associations between unique words and a set of repeating images (e.g., car) while hearing a prototypical image sound (e.g., engine starting). Memory performance on an immediate test vs. a test the next morning quantified overnight memory consolidation. Importantly, two image sounds were designated as TMR cues, with one cue delivered at SO UP states and the other delivered at SO DOWN states. A novel sound was used as a TMR control condition. Behavioral results revealed a significant reduction of overnight forgetting for words associated with UP-state TMR compared with words associated with DOWN-state TMR. Electrophysiological results showed that UP-state cueing led to enhancement of the ongoing UP state and was followed by greater spindle power than DOWN-state cueing. Moreover, UP-state (and not DOWN-state) cueing led to reinstatement of target image representations. Together, these results unveil the behavioral and mechanistic effects of delivering reminder cues at specific phases of endogenous sleep rhythms and mark an important step for the endeavor to experimentally modulate memories during sleep.