bluuebunny/crossref_metadata_2025 huggingface dataset:
Rb3B5O8F2and K0.6Rb2.4B5O8F2: two new deep-ultraviolet transparent nonlinear optical fluorooxoborates designed by cation regulation
Authors: Zhang Ruonan , Cheng Bingliang , Wang Xuping , Yang Rong , Yang Zhihua , Han Shujuan , Pan Shilie
Published: December 2022

Two new alkali metal fluorooxoborates, Rb3B5O8F2and K0.6Rb2.4B5O8F2, were successfully obtained by cation regulation, which exhibit a short UV cutoff edge and an appropriate SHG response.
Electrochemically induced amorphous and porous VOx/N-doped carbon spheres as a cathode for advanced aqueous zinc-ion batteries
Authors: Yuan Jujun , Gan Yunfei , Mou jirong , Ma Xiangdong , Li Xiaokang , Meng Junxia , Xu Lishuang , Zhang Xianke , He Haishan , Liu Jun
Published: December 2022

Vanadium-based oxides have captured considerable attention as ZIB cathodes benefiting from their rich valences and superior theoretical capacity.
Asymmetric modification of Anderson-type polyoxometalates towards organic–inorganic homo- and hetero-cluster oligomers
Authors: Zhang Meng-Meng , Yin Yi-An , Chen Wu-Ji , Lin Chang-Gen , Wei Yongge , Song Yu-Fei
Published: December 2022

We report here the successful synthesis and purification of asymmetrically modified Anderson clusters, and development of a robust coupling method for precision synthesis of organic–inorganic cluster oligomers.
Lithiophilic liquid metal layer induced lithium plating/stripping in a 3D Cu matrix to mitigate lithium dendrites and volume expansion
Authors: Guan Weiye , Lv Yang , Ma Chao , Zhang Qingxu , Wei Aofei , Liu Xizheng
Published: December 2022

A multi-gradient 3D porous current collector (MGC), comprising a lithiophilic gradient layer and a conductivity gradient layer, is prepared to serve as a Li metal battery anode. The bi-continuous gradient layers regulate the lithium flux and induce uniform Li deposition.
Visible-light-photocatalysis driven denitrogenative/radical 1,3-shift of benzotriazole: access to 3-aryl-aminoquinoxalin-2(1H)-one scaffolds
Authors: Yi Bing , Tang Huan , Yi Ziqi , Gong Huiling , Li Daiguang , Zhang Wenhui , Chen Yizheng , Tan Jian-Ping , Xie Yanjun
Published: December 2022

We described a visible-light-photocatalysis driven denitrogenative/radical 1,3-shift of benzotriazole to generate unusual aromatic amine radical which then undergo direct amination with quinoxalin-2(1H)-ones leading to 3-aryl-aminoquinoxalin-2(1H)-ones.
K2CO3-accelerated amidation of carboxylic acids using α-oxo ketene-N,S-acetals as amine surrogates
Authors: Yu Haifeng , Zhang Xue , Li Liangliang , Luo Hui , Che Guangbo
Published: December 2022

A novel and efficient K2CO3-accelerated amidation of carboxylic acids with α-oxo ketene-N,S-acetals as amine surrogates is developed.
Structure and dissolution of silicophosphate glass
Authors: Takada Kazuya , Tamura Tomoyuki , Kasuga Toshihiro
Published: December 2022

The solubility of P2O5–SiO2–Na2O–CaO glasses was suppressed by the coexistence of CaO and Na2O, attributed to the delocalization of the electron distribution of P in QP3 units coordinated to the six-fold-coordinated Si.
Bioactive 2-pyridone-containing heterocycle syntheses using multicomponent reactions
Authors: Hurtado-Rodríguez Diana , Salinas-Torres Angélica , Rojas Hugo , Becerra Diana , Castillo Juan-Carlos
Published: December 2022

This review provides a comprehensive overview of multicomponent reactions (MCRs) for the synthesis of biologically active 2-pyridone-containing heterocycles.
μ-Oxo-bis[(octacosafluoro-meso-tetraphenylporphyrinato)iron(iii)] – synthesis, crystal structure, and catalytic activity in oxidation reactions
Authors: Schuh Tristan , Kataeva Olga , Knölker Hans-Joachim
Published: December 2022

We describe the synthesis and crystal structure of a novel perfluorinated μ-oxo-bis[(porphyrinato)iron(iii)] complex enabling useful applications in catalytic C–H activations including asymmetric biaryl coupling and Wacker-type oxidation of olefins.
A framework for comparing the energy production of photovoltaic modules using 2-, 3-, and 4-terminal tandem cells
Authors: McMahon William E. , Geisz John F. , Buencuerpo Jeronimo , Warren Emily L.
Published: December 2022

Energy production, rather than efficiency, is the most important metric for comparing different configurations of tandem solar cells (2T, 3T, 4T), as each interconnection technique has its own advantages and disadvantages.
Ethanol to diesel: a sustainable alternative for the heavy-duty transportation sector
Authors: Restrepo-Flórez Juan-Manuel , Cuello-Penaloza Paolo , Canales Emmanuel , Witkowski Dustin , Rothamer David A. , Huber George W. , Maravelias Christos T.
Published: December 2022

Ethanol is catalytically upgraded to diesel.
Constructing a self-healing injectable SABA/Borax/PDA@AgNPs hydrogel for synergistic low-temperature photothermal antibacterial therapy
Authors: Zhu Hao , Cheng Xuedan , Zhang Junqing , Wu Qiang , Liu Chaoqun , Shi Jiahua
Published: December 2022

Here, a self-healing and injectable SABA/Borax/PDA@AgNPs hydrogel with satisfactory mechanical properties is prepared, which achieves considerable antibacterial efficacy both in vitro and in vivo.
Important roles of odontoblast membrane phospholipids in early dentin mineralization
Authors: Anada Risa , Hara Emilio Satoshi , Nagaoka Noriyuki , Okada Masahiro , Kamioka Hiroshi , Matsumoto Takuya
Published: December 2022

Phospholipids co-localized with collagen were found at the early stages of dentin mineralization in mouse first molar. Plasma membrane phospholipids induced rapid mineralization of collagen.
Remodeling of algal photosystem I through phosphorylation
Authors: Younas Muhammad , Scholz Martin , Marchetti Giulia Maria , Hippler Michael
Published: December 2022

Photosystem I (PSI) with its associated light-harvesting system is the most important generator of reducing power in photosynthesis. The PSI core complex is highly conserved, whereas peripheral subunits as well as light-harvesting proteins (LHCI) reveal a dynamic plasticity. Moreover, in green alga, PSI–LHCI complexes are found as monomers, dimers, and state transition complexes, where two LHCII trimers are associated. Herein, we show light-dependent phosphorylation of PSI subunits PsaG and PsaH as well as Lhca6. Potential consequences of the dynamic phosphorylation of PsaG and PsaH are structurally analyzed and discussed in regard to the formation of the monomeric, dimeric, and LHCII-associated PSI–LHCI complexes.
Design of high power density double‐stator permanent magnet synchronous motor
Authors: Guo Liyan , Wang Yangyang , Wang Huimin , Zhang Zhen
Published: December 2022

Compared with the traditional permanent magnet synchronous motor (PMSM), the double‐stator permanent magnet synchronous motor (DS‐PMSM) can utilise the internal space adequately and has high power density. In this study, the design method of this kind of motor will be researched. Different rotor magnetic circuit topologies are analysed while keeping the outer diameter of outer stator unchanged, and the rotor magnetic circuit topologies with higher power density are selected. Furthermore, the effects of pole‐arc coefficient and stator split ratio on the power density of the motor are analysed, so a high power density DS‐PMSM can be designed. On this basis, a kind of magnetic pole structure with unequal pole‐arc coefficient is proposed to solve the problem of large torque ripple in DS‐PMSM. Finally, the DS‐PMSM is investigated by the FEA, compared with the traditional single stator PMSM, the average torque of the DS‐PMSM is increased by 62.2%, and the torque ripple is only 3.2%.
Estimation of harmonic impedance and harmonic contribution with harmonic complex power in the absence of harmonic phase angle
Authors: Zheng Hongru , Xu Fangwei , Shu Qin , Wang Chuan , Zhou Quan
Published: December 2022

Estimation of harmonic impedances and harmonic contributions is beneficial to harmonic control, and harmonic phasors data is necessary for the existing estimation methods. However, the phase angles of harmonic phasors are not recorded in some of current power quality measuring instruments (such as Fluke 1760 etc.), which makes the existing methods unavailable. To solve this problem, the Norton equivalent circuit model under harmonic frequency is improved and a new model composed of harmonic complex power sources and harmonic impedances is proposed. Based on the model, the harmonic impedance and harmonic contribution can be estimated by using independent component analysis algorithm, and the harmonic phasor data is no longer required. The superiority of the proposed model is verified through simulation and field cases.
Influence of thermal ageing on high‐field polarisation characteristics and conductivity behaviour of submarine polymeric cables insulation
Authors: Dai Xize , Hao Jian , Montanari Gian Carlo , Jian Zheng , Liao Ruijin , Zheng Xinlong
Published: December 2022

Diagnosing insulation intrinsic ageing is essential for preventing insulation failure of submarine cables, and in case of failure, helping in any decision about maintenance actions. In this study, a novel aged cable diagnosis approach based on high‐voltage frequency domain spectroscopy (HV‐FDS) with broader frequency width is proposed to analyse the high‐field polarisation characteristics and conductivity behaviour of 500 kV submarine polymeric cables insulation, aiming to support the evaluation of overall insulation ageing. The measurement principle of HV‐FDS and relaxation mechanism are stated, and then focus is on studying the extent of change of polarisation and conduction properties of submarine cables insulation as a function of ageing stress and time. Moreover, the high‐field polarisation characteristics and conductivity behaviour are discussed in‐depth based on the carrier transport and trap properties. Finally, the novel diagnostic indicator based on the high‐field characteristics is extracted to quantify the thermal ageing state of submarine cables insulation. Results show that the high‐field polarisation characteristics and conductivity behaviour seem to become sensitive diagnostic quantities if measured at reasonably high voltage, which are able to reveal mechanisms associated with thermo‐oxidative ageing as that generated in the testing procedure considered in this paper. Sensitivity is considerably higher than that experienced in typical dielectric spectroscopy approaches.
Effect of SiO2 nano film deposited on copper and aluminium electrodes on the power frequency breakdown voltage of SF6 gas
Authors: Zheng Yu , Gong Shengle , Liu Lei , Xiang Zhihui , Lv Yichen , Yu Jianhui , Zhou Wenjun
Published: December 2022

In order to reveal the effect of insulating nano film on the insulation strength of SF6 gas gap, SiO2 nano film was deposited on the electrode surface by the plasma‐enhanced chemical vapour deposition technique. The power frequency breakdown characteristics of SF6 gas under Cu and Al electrodes were obtained before and after coating. The results showed that when the Cu electrode was coated, the breakdown voltage was up to at most 11.5% higher than that of an uncoated Cu electrode in the pressure range of 0.2–0.5 MPa. When the Al electrode was coated, the breakdown voltage of SF6 gas was lower than that of an uncoated one in the pressure range of 0.2–0.5 MPa. The breakdown voltage of SF6 gas under the Cu electrode was slightly lower than that under the Al electrode, but the breakdown voltages under the coated Cu electrode were significantly higher than that under the coated Al electrode. Through SEM tests, it was found that the surface roughness of the electrode decreases after coating, but particles were formed on the surface of the Al electrode. The content of metal fluoride formed on the coated Al electrode under multiple breakdowns was significantly higher than that on the coated Cu electrode. The research results could provide references for improving insulation performance of GIS equipment.
The CARMENES search for exoplanets around M dwarfs
Authors: Fuhrmeister B. , Czesla S. , Perdelwitz V. , Nagel E. , Schmitt J. H. M. M. , Jeffers S. V. , Caballero J. A. , Zechmeister M. , Montes D. , Reiners A. , López-Gallifa Á. , Ribas I. , Quirrenbach A. , Amado P. J. , Galadí-Enríquez D. , Béjar V. J. S. , Danielski C. , Hatzes A. P. , Kaminski A. , Kürster M. , Morales J. C. , Zapatero Osorio M. R.
Published: December 2022

It is clearly established that the Sun has an 11-yr cycle that is caused by its internal magnetic field. Such a cycle is also observed in a sample of M dwarfs. In the framework of exoplanet detection or atmospheric characterisation of exoplanets, the activity status of the host star plays a crucial role, and inactive states are preferable for such studies. This means that it is important to know the activity cycles of these stars. We study systematic long-term variability in a sample of 211 M dwarfs observed with CARMENES, the high-resolution optical and near-infrared spectrograph at Calar Alto Observatory. In an automatic search using time series of different activity indicators, we identified 26 stars with linear or quadratic trends or with potentially cyclic behaviour. Additionally, we performed an independent search in archival R′HK data collected from different instruments whose time baselines were usually much longer. These data are available for a subset of 186 of our sample stars. Our search revealed 22 cycle candidates in the data. We found that the percentage of stars showing long-term variations drops dramatically to the latest M dwarfs. Moreover, we found that the pseudo-equivalent width (pEW) of the Hα and Ca II infrared triplet more often triggers automatic detections of long-term variations than the TiO index, differential line width, chromatic index, or radial velocity. This is in line with our comparison of the median relative amplitudes of the different indicators. For stars that trigger our automatic detection, this leads to the highest amplitude variation in R′HK, followed by pEW(Hα), pEW(CaII IRT), and the TiO index.
Dynamic transmission-reflection dichroism based on humidity-responsive metal-hydrogel-metal nanocavities
Authors: Wang Dandan , Li Qiang , Ying Yunbin , Li Runhu , Cheng Mingliang , Chen Yingxin , Zhang Jian , Zhang Xuefeng
Published: December 2022

“Lycurgus cup” effect, referring dichroism between reflection and transmission modes of the same structures, is a peculiar phenomenon of multi-faceted display in structural color. Beyond the static dichrotic display, the realization of dynamic dichroism desires active materials and tunable structures, and owns the great demand from smart display, anti-counterfeiting and environmental sensing. We hereby propose a metal-hydrogel-metal (MHM) nanocavity for dynamic dichrotic display. This structure includes thin silver layers to induce the partial transmission with the existing reflection, and a polyvinyl alcohol (PVA) hydrogel layer owning the swelling/deswelling deformability to humidity change. The following experimental measurements and theoretical analysis prove that the reflection and transmission modes exist at distinct wavelengths, and the swelling hydrogel layer by humidity change between 10 and 90% RH can dynamically modulate the dichrotic resonance with the wavelength shift over 100 nm. Such environmental-sensitive and real-time tunable dichroism with hydrogel-based structural color is then verified for multi-color printing, resolution test, and cycling test.
Application of jute mattings to control growth of submerged macrophytes in a shallow clear-water pond
Authors: Francová Kateřina , Veselý Lukáš , Vrba Jaroslav , Duras Jindřich
Published: December 2022

The jute mattings of two different densities were tested to control growth of Elodea canadensis Michx. and Myriophyllum spicatum L. in the Velký Bolevecký pond (West Bohemia, Czechia) during fourteen months. Both jute densities prove to be effective, permeable and stayed intact for one year. Results showed significant interaction among species, jute density and date in both abundance and length of Elodea and Myriophyllum fragments. When tested separately, we found the significant difference between abundance of Elodea and Myriophyllum fragments on the jute mattings, among the sites, and in time, but not between the two jute densities. Elodea dominated the sites due to spread of fragments from mowing that continued at the pond. However, the fragment length of given species varied between the two jute densities. They might easier root, but it could be also explained by the variability of sampled quadrats. Fragment lengths of Elodea and Myriophyllum were also changing in time but the length did not significantly differ between the two species or among the sites. Although Elodea and Myriophyllum dominated the jute mattings by the end, their progress was slower than in control sites.
The Effects of Environmental Variables on the Distribution of Immature Black Flies (Diptera, Simuliidae) in Various Streams of Northeastern Turkey
Authors: Başören Özge , Kazancı Nilgün
Published: December 2022

The Eastern Black Sea Region of Turkey is located in the Caucasus Ecoregion and is one of the richest regions of the world in terms of biodiversity. Black flies are an important part of the biodiversity of running waters in the region. To determine the Simuliidae fauna of this region and understand the relationships between species distribution and environmental variables, 41 sites, mostly unpolluted or slightly polluted, were sampled in July 2008 and June 2009. A total of 3309 simulids and 20 species were identified. The most frequent and the most abundant species wereSimulium variegatumMeigen, 1818,Simulium bezziiCorti, 1914, andSimulium trifasciatumCurtis, 1839.Simulium costatumFriedrichs, 1920, Simulium argenteostriatumStrobl, 1898, Simulium angustipesEdwards, 1915, Simulium balcanicumEnderlein, 1924, andSimulium pseudequinumSeguy, 1921 were positively correlated with NO2–N, water temperature, and pH but negatively correlated with PO4–P and dissolved oxygen.Simulium argyreatumMeigen, 1838, S. variegatum, andS. trifasciatumwere positively correlated with dissolved oxygen.Simulium ornatumMeigen, 1818 was negatively correlated with pH.Prosimulium tomosvaryiEnderlein, 1921,Simulium cryophilumRubtsov, 1959,Simulium vernumMacquart, 1826, andSimulium hispaniolaGrenier and Bertrand, 1954 were negatively correlated with electrical conductivity. The results indicate that black flies, like other benthic macroinvertebrates, also respond to changes in environmental conditions with changes in composition and distribution. We hope that our research will contribute to biomonitoring studies in the future.
Risk communication in the recovery phase after a nuclear accident: the contribution of the “co-expertise process”
Authors: Thu Zar W. , Lochard J. , Taira Y. , Takamura N. , Orita M. , Matsunaga H.
Published: December 2022

Risk communication in post-nuclear accident situations faces many challenges related to the limited knowledge of experts about the actual situation in the affected communities, as well as of the affected people about radiological risk combined with their distrust of authorities and experts. In such an anxiety-provoking context, the co-expertise approach recommended by the ICRP combining technical expertise, citizen participation and two-way communication has shown that it was an effective approach for restoring trust between the experts and the people concerned and developing, among the latter, a practical radiological protection culture. In essence, technical-oriented risk communication is not sufficient alone. A dialogue with affected people is necessary in combination with measurements of radiation associated with their daily life in order to gain their participation in the co-expertise process and to progressively restore confidence in them and trust in authorities and experts. The article highlights the salient features of the co-expertise process in relation to risk communication.
Transportation problem in Fermatean fuzzy environment
Authors: Sahoo Laxminarayan
Published: December 2022

Due to the uncertain economic and environmental situations of the society, it is impossible to quantify the supply, demand, and transportation costs of a transportation problem precisely. The purpose of this paper is to address the transportation problem where supply, demand, and transportation costs are Fermatean fuzzy numbers. Numerous approaches to addressing transportation problems with fuzzy parameters have been suggested in the literature to date, but in each of these approaches, the parameters corresponding to the transportation problems are either generalized fuzzy numbers or Pythagorean fuzzy numbers. With the help of Fermatean fuzzy sets (FFSs), a relatively new concept, one can manage ambiguous information more simply throughout the decision-making process. As a result, we have used Fermatean fuzzy parameters to solve the transportation problem in this research. Here, we have developed an algorithm to solve the transportation problem with Fermatean fuzzy parameters and have also solved the problem using the existing method. Then, the optimal value can be obtained using arithmetic operations on Fermatean fuzzy numbers. We have solved a numerical example to demonstrate the proposed methodology, and the obtained results are presented and compared with the existing literature. The importance of the research and the scope of further research are then highlighted.
Carbapenemase-bildende Enterobakterien (CBE)
Authors: Pfeifer Yvonne , Wendt Sebastian , Lippmann Norman , Lübbert Christoph
Published: December 2022

Carbapenemasen sind bakterielle Enzyme, die Carbapeneme und andere
Beta-Laktam-Antibiotika inaktivieren. Viele gramnegative Spezies, darunter vor allem
Enterobakterien, können Carbapenemasen bilden, was die therapeutischen
Möglichkeiten im Infektionsfall stark einschränkt.
Approaches to Interdisciplinary Care for Infants with Severe Bronchopulmonary Dysplasia: A Survey of the Bronchopulmonary Dysplasia Collaborative
Authors: Cristea A. Ioana , Tracy Michael C. , Bauer Sarah E. , Guaman Milenka Cuevas , Welty Stephen E. , Baker Christopher D. , Bhombal Shazia , Collaco Joseph M. , Courtney Sherry E. , DiGeronimo Robert J. , Eldredge Laurie C. , Gibbs Kathleen , Hayden Lystra P. , Keszler Martin , Lai Khanh , McGrath-Morrow Sharon A. , Moore Paul E. , Rose Rebecca , Sindelar Richard , Truog William E. , Nelin Leif D. , Abman Steven ,   for the BPD Collaborative
Published: December 2022

Objective Bronchopulmonary dysplasia (BPD) remains the most common late morbidity for extremely premature infants. Care of infants with BPD requires a longitudinal approach from the neonatal intensive care unit to ambulatory care though interdisciplinary programs. Current approaches for the development of optimal programs vary among centers.

Study Design We conducted a survey of 18 academic centers that are members of the BPD Collaborative, a consortium of institutions with an established interdisciplinary BPD program. We aimed to characterize the approach, composition, and current practices of the interdisciplinary teams in inpatient and outpatient domains.

Results Variations exist among centers, including composition of the interdisciplinary team, whether the team is the primary or consult service, timing of the first team assessment of the patient, frequency and nature of rounds during the hospitalization, and the timing of ambulatory visits postdischarge.

Conclusion Further studies to assess long-term outcomes are needed to optimize interdisciplinary care of infants with severe BPD.

Key Points
Virtual Surgical Planning and 3D-Printed Surgical Guides in Facial Allotransplantation
Authors: Vyas Krishna , Suchyta Marissa , Gibreel Waleed , Martinez-Jorge Jorys , Bite Uldis , Sharaf Basel A. , Bradley Elizabeth A. , Amer Hatem , Bakri Karim , Mardini Samir
Published: December 2022

The complex three-dimensional (3D) anatomy in facial allotransplantation creates a unique challenge for surgical reconstruction. Evolution of virtual surgical planning (VSP) through computer-aided design and computer-aided manufacturing has advanced reconstructive outcomes for many craniomaxillofacial indications. Surgeons use VSP, 3D models, and surgical guides to analyze and to trial surgical approaches even prior to entering the operating room. This workflow allows the surgeon to plan osteotomies and to anticipate challenges, which improves surgical precision and accuracy, optimizes outcomes, and should reduce operating room time. We present the development, evolution, and utilization of VSP and 3D-printed guides in facial allotransplantation at our institution, from guide conception to first clinical case.
Prioritization preferences for COVID-19 vaccination are consistent across five countries
Authors: Munzert Simon , Ramirez-Ruiz Sebastian , Çalı Başak , Stoetzer Lukas F. , Gohdes Anita , Lowe Will
Published: December 2022

Vaccination against COVID-19 is making progress globally, but vaccine doses remain a rare commodity in many parts of the world. New virus variants require vaccines to be updated, hampering the availability of effective vaccines. Policymakers have defined criteria to regulate who gets priority access to the vaccination, such as age, health complications, or those who hold system-relevant jobs. But how does the public think about vaccine allocation? To explore those preferences, we surveyed respondents in Brazil, Germany, Italy, Poland, and the United States from September to December of 2020 using ranking and forced-choice tasks. We find that public preferences are consistent with expert guidelines prioritizing health-care workers and people with medical preconditions. However, the public also considers those signing up early for vaccination and citizens of the country to be more deserving than later-comers and non-citizens. These results hold across measures, countries, and socio-demographic subgroups.
Gate-tunable step-like current through a single-molecule junction
Authors: Petrov E. G. , Teslenko V. I.
Published: December 2022

Using the kinetic approach, analytical expressions are obtained for the sequential and direct tunneling components of the current in a molecular junction, where the molecule acts as a mediator for interelectrode electron transfer. Within the framework of the modified HOMO-LUMO model, it is shown that the current components are not independent even with weak interaction of the molecule with the electrodes but are interrelated kinetically through processes that lead to the occupation of the electronic states of a charged and neutral molecule. As an application of the theory, the critical voltages determining the ranges of resonant steplike electron transfer through a junction with a planar ZnPc molecule are estimated. The values of the gate voltages at which the junction is capable of performing the functions of photoemitter are presented.
Controlling the structure of a glow discharge by supersonic gas flow
Authors: Shamsutdinov R. S. , Timerkaev B. A. , Petrova O. A. , Saifutdinov A. I.
Published: December 2022

The effect of supersonic gas flow on glow discharge characteristics in interelectrode space is studied. First, gas outflow through a Laval nozzle with a central body was simulated: gas particle density distributions, gas flow velocity, Mach number, and temperature were obtained. Next, these profiles were used for numerical calculations of the parameters of a transverse glow discharge within the framework of an extended fluid description of the plasma. As a result, it was found that the cathode zones can both shrink and stretch depending on the parameters of the supersonic gas flow. The latter creates an inhomogeneous gas density in the interelectrode region and thereby affects the value of E/N, which determines the electrical characteristics of the discharge. Numerical simulation results are confirmed by experimental data.
Metastability for the degenerate Potts model with negative external magnetic field under Glauber dynamics
Authors: Bet Gianmarco , Gallo Anna , Nardi Francesca R.
Published: December 2022

We consider the ferromagnetic q-state Potts model on a finite grid with a non-zero external field and periodic boundary conditions. The system evolves according to Glauber-type dynamics described by the Metropolis algorithm, and we focus on the low temperature asymptotic regime. We analyze the case of a negative external magnetic field. In this scenario, there are q − 1 stable configurations and a unique metastable state. We describe the asymptotic behavior of the first hitting time from the metastable state to the set of the stable states as β → ∞ in probability, in expectation, and in distribution. We also identify the exponent of the mixing time and find an upper bound and a lower bound for the spectral gap. We identify the minimal gates for the transition from the metastable state to the set of the stable states and for the transition from the metastable state to a fixed stable state. Furthermore, we identify the tube of typical trajectories for these two transitions. The detailed description of the energy landscape that we develop allows us to give precise asymptotics for the expected transition time from the unique metastable state to the set of the stable configurations.
Eigenvalues of the Dirac operator on compact spin manifolds under Ricci flow
Authors: Li Yuqiao
Published: December 2022

In this paper, we first derive the evolution formula for the square of the first eigenvalue λ2 of the Dirac operator under the metric flow ∂∂tg=h on compact spin manifolds. We then prove that λ2 is nondecreasing under the Ricci flow on compact spin surfaces with non-negative Gauss curvature.
High-order corrections to the radiation-free dynamics of an electron in the strongly radiation-dominated regime
Authors: Samsonov A. S. , Nerush E. N. , Kostyukov I. Yu.
Published: December 2022

A system of reduced equations is proposed for electron motion in the strongly radiation-dominated regime for an arbitrary electromagnetic field configuration. The approach developed here is used to analyze various scenarios of electron dynamics in this regime: motion in rotating electric and magnetic fields and longitudinal acceleration in a plane wave and in a plasma wakefield. The results obtained show that this approach is able to describe features of electron dynamics that are essential in certain scenarios, but cannot be captured in the framework of the original radiation-free approximation [Samsonov et al., Phys. Rev. A 98, 053858 (2018) and A. Gonoskov and M. Marklund, Phys. Plasmas 25, 093109 (2018)]. The results are verified by numerical integration of the nonreduced equations of motion with account taken of radiation reaction in both semiclassical and fully quantum cases.
Analytic model of principal Hugoniot at all pressures
Authors: Burakovsky L. , Preston D. L. , Ramsey S. D. , Baty R. S.
Published: December 2022

We present the analytic form of the principal Hugoniot at all pressures. It is constructed by interpolating smoothly between three pressure (P) regimes. Specifically, (i) the low-P regime in which the Hugoniot is described by Us=C+BUp+AUp2, where Up and Us are particle and shock velocities, respectively, the values of C and B come from the experiment, and a small non-linearity (A∼10−2 s/km) is added to the otherwise common linear form Us=C+BUp to match the next regime; (ii) the intermediate-P regime where the Hugoniot is described by the quantum-statistical model of Kalitkin and Kuzmina, Us=c+bUp+aUp2, with the values of c, b, and a determined virtually for all Zs (Z being the atomic number); and (iii) the high-P regime in which the Hugoniot is described by the Debye–Hückel model developed by Johnson. We determine the analytic form of the Hugoniot in the high-P regime and match it with those in the other two regimes. We show that no additional free parameter is required for the construction of the Hugoniot at all P except the six mentioned above: C, B, c, b, a, and Z. Comparison of the new model to experimental and/or theoretical data on aluminum, iron, silicon, and lithium fluoride, the four materials for which such data exist to very high P, demonstrates excellent agreement. Our approach applies to both elemental substances and complex materials (compounds and alloys) and can be used to predict the analytic forms of the yet unknown Hugoniots as well as to validate experimental results and theoretical calculations. The new model can be adopted for the description of the principal Hugoniots of porous substances and can be generalized for radiation-dominated (strong) shocks.
Threshold voltage instability by charge trapping effects in the gate region of p-GaN HEMTs
Authors: Greco Giuseppe , Fiorenza Patrick , Giannazzo Filippo , Bongiorno Corrado , Moschetti Maurizio , Bottari Cettina , Alessandrino Mario Santi , Iucolano Ferdinando , Roccaforte Fabrizio
Published: December 2022

In this work, threshold voltage instability of normally off p-GaN high electron mobility transistors has been investigated by monitoring the gate current density during a device on-state. The origin of gate current variations under stress has been ascribed to charge trapping occurring at different interfaces in the metal/p-GaN/AlGaN/GaN system. In particular, depending on the stress bias level, electrons (VG < 6 V) or holes (VG > 6 V) are trapped, causing a positive or negative threshold voltage shift ΔVTH, respectively. By monitoring the gate current variations at different temperatures, activation energies associated with the electrons and holes trapping could be determined and correlated with the presence of nitrogen (electron traps) or gallium (hole traps) vacancies. Moreover, the electrical measurements suggested the generation of a new electron-trap upon long-time bias stress, associated with the creation of crystallographic dislocation-like defects extending across different interfaces (p-GaN/AlGaN/GaN) of the gate stack.
A data-driven optimal disturbance procedure for free-stream turbulence induced transition
Authors: Dotto A. , Barsi D. , Lengani D. , Simoni D.
Published: December 2022

The investigation of free-stream turbulence induced transition by means of simple and effective numerical methods traditionally represents a major challenge in the aerodynamic field. In this work, a data-driven algorithm aimed at obtaining optimal forcing and response concerning free-stream turbulence induced boundary layer transition is introduced. The method, referred to as Data-driven Optimal Disturbance (DOD) in the following, relies on dynamic mode decomposition to compute the linear matrix responsible for disturbance evolution in the streamwise direction and opens the possibility for optimal disturbance analysis in an equation-free manner. The procedure has been applied to high-fidelity large-eddy simulation (LES) results concerning zero pressure gradient flows. Four different combinations of turbulence intensity Tu and integral length scale Lg have been adopted as boundary conditions to investigate the sensitivity of the transition route to the free-stream turbulence properties. Overall, DOD applied within the transitional region identifies highly energetic turbulent scales embedded in the free-stream as the optimal forcing inducing the formation of streaky structures within the boundary layer. Furthermore, streaky structures characterized by the same spanwise wavelength observed in the LES results are identified by DOD as the boundary layer response to the optimal forcing. Finally, the amplification of disturbances provided by DOD along the streamwise direction clearly resembles the well-established transient growth. Thus, DOD appears a useful tool to analyze the free-stream turbulence induced transition of boundary layers by a simple equation-free algorithm merely based on data analytics.
The linear-time-invariance notion to the Koopman analysis: The architecture, pedagogical rendering, and fluid–structure association
Authors: Li Cruz Y. , Chen Zengshun , Lin Xisheng , Weerasuriya Asiri Umenga , Zhang Xuelin , Fu Yunfei , Tse Tim K. T.
Published: December 2022

This work augments a Linear-Time-Invariance (LTI) notion to the Koopman analysis, finding an invariant subspace on which consistent Koopman modes are expanded with fluid mechanics implications. The work also develops the Koopman-LTI architecture—a systematic procedure to associate fluid excitation and structure surface pressure by matching Koopman eigen tuples, establishing fluid–structure correspondences that examine fluid–structure interactions (FSIs) at new angles. The data-driven, modular architecture also exhibits the potential to evolve with advances in Koopman algorithms. A pedagogical prism wake example demonstrated that the Koopman-LTI generated a near-perfect linearization of nonlinear FSI dynamics involving inhomogeneous anisotropic turbulence, with mean and root-mean-squared errors of O−12 and O−9, respectively; the infinite-dimensional Koopman modes were also approximated with O−8 error. The subcritical wake during shear layer transition II was also reduced into only six dominant excitation-response Koopman duplets. The upstream and crosswind walls constitute a dynamically unified interface dominated by only two mechanisms. The downstream wall remains a distinct interface and is dominated by four other mechanisms. The complete revelation of the prism wake comes down to understanding the six mechanisms, which Part II [Li et al., “A parametric and feasibility study for data sampling of the dynamic mode decomposition: Range, resolution, and universal convergence states,” Nonlinear Dyn. 107(4), 3683–3707 (2022)] will address by investigating the physics implications of the duplets' in-synch phenomenological features. Finally, the analysis revealed z-velocity's marginal role in the convection-dominated free-shear flow, Reynolds stresses' spectral description of cascading eddies, wake vortices' sensitivity to dilation and indifference to distortion, and structure responses' origin in vortex activities.
On the crown formation and cavity dynamics of free-falling thick disks
Authors: Janati Mahsa , Azimi Amir Hossein
Published: December 2022

The water entry, crown formation, and cavity dynamics of gravity-driven thick solid and annular disks were studied by conducting a series of detailed laboratory experiments. Three different release conditions were examined to study the fully guarded and partially guarded release conditions on the cavity dynamics. The effects of aspect ratio, geometry, and density of disks on crown formation, interface impact, seal development, and air entrainment were investigated. Four crown shapes were identified, and the crown structure was classified based on the dimensionless moment of inertia, I*, and the impact Froude number, Fro. The effects of controlling parameters on variations of crown dimensions were investigated. It was found that the normalized crown diameter decreased with I* and crown geometries were found to be smaller in annular disks. Experimental observations have shown that high-density disks have larger pinch-off depth and form a deep seal in the ambient water. The normalized pinch-off depth increased with Fro and the normalized pinch-off depth in cylindrical thick disks were smaller than thin disks and spherical objects. The temporal variations of cavity indicated a non-linear correlation between the growth rate of normalized pinch-off depth and time. The disk's velocities in three different stages were measured, it was found that the settling velocities followed a linear relationship with I*, and it was affected by the release conditions. The velocity and vortex fields were extracted from the particle image velocimetry data. The velocity fields showed that the solid disks affected a greater surrounding ambient in comparison to the annular disks due to their higher initial momentum. Periodic vortex shedding was formed in the wake of annular disks, and the frequency of the vortex field was found to be proportional to the disk density.
Drop impact on a sessile soap bubble
Authors: Zhang Xurui , Jian Zhen , Hou Boyu , Thoraval Marie-Jean
Published: December 2022

The dynamics of a water droplet impacting onto a soap bubble sitting on a solid substrate was experimentally investigated using a high-speed camera. At low impact velocities, the droplet bounced on the soap bubble. Varying the size of the soap bubble, we discovered two regimes at high impact velocities. For a soap bubble larger than a critical dimensionless height of 3.18, the water droplet passed through the soap film, while the soap bubble burst as the bubble height was less than the critical value. Theoretical models were proposed for the critical impact velocities needed to reach these two regimes, with their intersection correctly capturing the critical bubble height separating them. Two mechanisms for the bursting of the soap bubble were identified depending on the location where the bursting started, either from the center below the impacting droplet or from the periphery of the soap film. Moreover, the bursting of the soap bubble could be suppressed by replacing the solid substrate below the bubble with a tube.
New exact spatially localized solutions of the (3 + 1)-dimensional Charney–Obukhov equation for the ocean
Authors: Kudryavtsev A. G. , Myagkov N. N.
Published: December 2022

New exact spatially localized solutions on the background of a zonal flow, propagating along the zonal direction at a constant velocity, are found for the (3 + 1)-dimensional nonlinear Charney–Obukhov equation describing Rossby waves and vortices in ocean. In total, five solutions are presented—two solutions with spherical symmetry and three solutions with cylindrical symmetry. One of the solutions with spherical symmetry is constructed using the Darboux transformation. Visualization of the solutions found shows that, depending on the values of the parameters included in the solutions, they can describe both an irrotational flow and a vortex flow with 1, 2, or more localized vortices. To analytically estimate the vertical localization of vortices, the necessary condition for the instability of the zonal flow and the condition for the maximum total vorticity are used. These estimates are in good agreement with the results of visualization of the vortex flow for the solutions found.
Temperature response to periodic modulation in internal heating convection
Authors: Xia Zhi-Lin , Zhao Chao-Ben , Wu Jian-Zhao , Wang Bo-Fu , Chong Kai Leong
Published: December 2022

Thermal convection in nature and industrial applications usually encounters time-varying internal heating (IH); however, the effect of temporal modulation on temperature responses and heat fluxes of the system has been rarely explored. Here, we numerically studied the IH convection with a temporally periodic heating source. We conducted direct numerical simulations over Rayleigh number (Ra) range 105≤Ra≤109 at fixed Prandtl number Pr = 1 with dimensionless modulation frequency 4×10−5≤f≤10−1 and amplitude fixed at Ω = 1. We first find that the introduction of periodic modulation has a slight effect on the heat transport over the individual plates and flow strength except for the lowest Ra. We then focus on the characteristics of the amplitude A and phase lag Δϕ of the globally averaged temperature response to the periodic modulation. Three regimes of the phase response are identified: (i) in-phase regime, where synchronous response is found at small frequencies with the vanished phase lag Δϕ and A keeping at constant value; (ii) transition regime, where both Δϕ and A decrease with increasing f for moderate frequencies; and (iii) half anti-phase regime, where Δϕ attains the minimal value −π/2. We also find that the transition behavior between three regimes can be well described using the normalization of the Ra-dependent critical frequency with the scaling Ra−0.30. To explain the regime transition, we further theoretically deduce an analytical solution for A and Δϕ, which agrees well with the numerical results. This solution can explain why fRa0.30 gives a good description of the transition behavior. Our present findings provide a fundamental understanding of the underlying mechanism of temporal modulation on IH systems and have substantial implications for the investigation of convective system with periodic heating source.
What can we obtain from the initial conditions of assimilating wind tower observation to improve near-surface meteorological elements?
Authors: Zhang Feimin , Zhu Yijie , Jin Shuanglong , Yang Yi , Yang Kai , Wang Chenghai , Zhao Lin
Published: December 2022

Accurate initial condition is prerequisite to an accurate prediction/forecast of near-surface meteorological elements and wind power. Although assimilating wind tower observations of wind farms in the initial condition has been proved feasible to improve the prediction, how and why assimilating wind tower observation improves initial condition are unclear. This study aims to improve the prediction by obtaining effective information from the initial conditions of assimilating wind tower observations. Results suggest that assimilating wind tower observations has local impacts on the initial condition, and the improvement of the initial condition is significantly related to the observed near-surface atmospheric stability. The forecast improvement by assimilating wind tower observations depends on two effective information: determining whether the initial condition is improved and the length of the improved initial condition can positively impact the forecast results. When the initial condition improves, forecast improvements can persist for about 12 h and are most distinct in the ultra-short term (0–4 h). Using the two effective information not only can distinctly improve the forecasts of near-surface wind, temperature, relative humidity, and wind power, but also can eliminate the stochastic forecasts. When the initial condition improves by assimilation, enhancing nudging intensity will have more positively impact on the prediction, and the root mean square error and mean absolute error in the ultra-short term can be reduced by 0.39 and 0.44 m s−1 for near-surface wind and 66.64 and 79.09 kW for wind power, respectively.
An easy-to-implement highly efficient algorithm for nonlinear Kutta condition in boundary element method
Authors: Wang Youjiang
Published: December 2022

An easy-to-implement highly efficient algorithm for the nonlinear Kutta condition in the boundary element method is proposed. The main innovation is to pre-calculate an inverse matrix and use it to replace a solving system of equations with vector–scalar multiplication and matrix–vector multiplication. This allows calculating the Jacobian matrix in each nonlinear Kutta condition iteration with little computational effort, which is important for fast and robust convergence. The open-water characteristics of four different propellers are calculated with the linear and nonlinear Kutta conditions. The simulations show that the nonlinear Kutta condition results in more accurate open-water characteristics and more physically reasonable surface pressure distributions. In addition, the nonlinear Kutta condition takes no more than 3 extra seconds for an open-water simulation, and this extra time does not increase much with the number of simulation steps. The method proposed in this work is expected to improve the computational speed of the boundary element method while maintaining the same accuracy, or improve the accuracy with little extra computational time.