bluuebunny/crossref_metadata_2025 huggingface dataset:
Synthesis and N–C bond cleavage reactions for cyclic phosphazenium dications
Authors: Miao Linkun , Yeganeh-Salman Amir , Yeung Jason , Stephan Douglas W.
Published: November 2024

The dicationic salts, [(C6H4)(PPh2)2(μ-NMe)][B(C6F5)4]2 and [(C2H4)(PPh2)2(μ-NR)][B(C6F5)4]2 (R = Me, CH2CHCH2, CH2Ph) are prepared and shown to react with [nBu4N]Cl to generate the phosphazenium cations and the corresponding alkyl-chloride.
Lycium ruthenicum Murray anthocyanin-driven neuroprotection modulates the gut microbiome and metabolome of MPTP-treated mice
Authors: Cao Hongdou , Tian Qi , Chu Liwen , Wu Lingyu , Gao Hua , Gao Qinghan
Published: November 2024

Emerging evidence suggests that Parkinson's disease (PD) is strongly associated with altered gut microbiota.
Controlled bioorthogonal catalyst self-assembly and activity using rationally designed polymer scaffolds
Authors: Huang Rui , Hirschbiegel Cristina-Maria , Luther David C. , Li Cheng-Hsuan , Nabawy Ahmed , Park Jungmi , Ribbe Alexander , Xu Yisheng , Rotello Vincent M.
Published: November 2024

Polymer-based nanocatalysts can mediate the bioorthogonal uncaging of substrates to form therapeutic molecules in situ. The supramolecular interactions within the host scaffold allow for the generation of thermo-responsive nanocatalysts.
Improving dynamic control of toehold-mediated strand displacement reactions through phosphorothioate modifications
Authors: Liang Ruyi , Shen Yiyang , Long Tanqing , Yang Peilin , Xu Chuanrui , Wu Tongbo , Zhang Mingxia
Published: November 2024

The discovery for the first time that phosphorothioate modifications can enhance the rate of TMSD in the short toehold region. Furthermore, we applied our findings to CHA circuits and DNA probabilistic circuits.
Cp*Co(iii)-catalyzed synthesis of isoquinolones via controlled annulation of primary arylamides with internal alkynes
Authors: Mishra Saksham , Baghel Akanksha Singh , Kumar Amit
Published: November 2024

A direct and efficient method has been developed for synthesis of isoquinolones from arylamides and internal alkynes using earth abundant Co(iii) salt as the catalyst. This approach employs a weakly coordinating primary amide as directing group.
Performance comparison of the Shack-Hartmann and pyramid wavefront sensors with a laser guide star for 40 m telescopes
Authors: Oyarzún F. , Heritier C. , Chambouleyron V. , Fusco T. , Rouquette P. , Neichel B.
Published: November 2024

Context. Upcoming giant segmented mirror telescopes will use laser guide stars (LGS) for their adaptive optics (AO) systems. Two options of wavefront sensors (WFSs) are the Shack-Hartmann wavefront sensor (SHWFS) and the pyramid wavefront sensor (PWFS).

Aims. In this paper, we compare the noise performance of the PWFS and the SHWFS. We aim to identify which of the two is best to use in the context of a single or tomographic configuration.

Methods. To compute the noise performance, we extended a noise model developed for the PWFS to be used with the SHWFS. To do this, we expressed the centroiding algorithm of the SHWFS as a matrix-vector multiplication, which allowed us to use the statistics of noise to compute its propagation through the AO loop. We validated the noise model with end-to-end simulations for telescopes of 8 and 16 m in diameter.

Results. For an AO system with only one WFS, we found that given the same number of subapertures, the PWFS outperforms the SHWFS. For a 40 m telescope, the limiting magnitude of the PWFS is around one magnitude higher than the SHWFS. When using multiple WFS and a generalized least-squares estimator to combine the signal, our model predicts that in a tomographic system, the SHWFS performs better than the PWFS (with a limiting magnitude that is higher by a 0.3 magnitude. When using sub-electron RON detectors for the PWFS, the performance quality is almost identical for the two WFSs.

Conclusions. We find that when using a single WFS with LGS, PWFS is a better alternative than the SH. For a tomographic system, both sensors would give roughly the same performance.
JOYS+ study of solid-state 12C/13C isotope ratios in protostellar envelopes
Authors: Brunken N. G. C. , van Dishoeck E. F. , Slavicinska K. , le Gouellec V. J. M. , Rocha W. R. M. , Francis L. , Tychoniec L. , van Gelder M. L. , Navarro M. G. , Boogert A. C. A. , Kavanagh P. J. , Nazari P. , Greene T. , Ressler M. E. , Majumdar L.
Published: November 2024

Context. The carbon isotope ratio is a powerful tool for studying the evolution of stellar systems due to its sensitivity to the local chemical environment. Recent detections of CO isotopologs in disks and exoplanet atmospheres revealed a high variability in the isotope abundance, ponting towards significant fractionation in these systems. In order to fully understand the evolution of this quantity in stellar and planetary systems, however, it is crucial to trace the isotope abundance from stellar nurseries to the time of planet formation. During the protostellar stage, the multiple vibrational modes of CO2 and CO ice, which peak in the near- and mid-infrared, provide a unique opportunity to examine the carbon isotope ratio in the solid state. With the current sensitivity and wide spectral coverage of the James Webb Space Telescope, the multiple weak and strong absorption features of CO2 and CO have become accessible at a high signal-to-noise ratio in solar-mass systems.

Aims. We aim to study the carbon isotope ratio during the protostellar stage by deriving column densities and ratios from the various absorption bands of CO2 and CO ice, and by comparing our results with the ratios derived in other astronomical environments.

Methods. We quantify the 12CO2/13CO2 and the 12CO/13CO isotope ratios in 17 class 0/I low-mass protostars from the 12CO2 ν1 + ν2 and 2ν1 + ν2 combination modes (2.70 µm and 2.77 µm), the 12CO2 ν3 stretching mode (4.27 µm), the 13CO2 ν3 stretching mode (4.39 µm), the 12CO2 ν2 bending mode (15.2 µm), the 12CO 1-0 stretching mode (4.67 µm), and the 13CO 1-0 stretching mode (4.78 µm) using the James Webb Space Telescope NIRSpec and MIRI observations. We also report a detection of the 2-0 overtone mode of 12CO at 2.35 µm.

Results. The column densities and 12CO2/13CO2 ratios derived from the various CO2 vibrational modes agree within the reported uncertainties, and we find mean ratios of 85 ± 23, 76 ± 12, and 97 ± 17 for the 2.70 µm band, the 4.27 µm band, and the 15.2 µm band, respectively. The main source of uncertainty on the derived values stems from the error on the band strengths; the observational errors are negligible in comparison. Variation of the 12CO2/13CO2 ratio is observed from one source to the next, which indicates that the chemical conditions of their envelopes might be genuinely different. The 12CO/13CO ratios derived from the 4.67 µm band are consistent, albeit elevated with respect to the 12CO2/13CO2 ratios, and we find a mean ratio of 165 ± 52.

Conclusions. These findings indicate that ices leave the prestellar stage with elevated carbon isotope ratios relative to the overall values found in the interstellar medium, and that fractionation becomes a significant factor during the later stages of star and planet formation.
Unveiling key factors in solar eruptions leading to the solar superstorm in 2024 May
Authors: Wang Rui , Liu Ying D. , Zhao Xiaowei , Hu Huidong
Published: November 2024

NOAA active region (AR) 13664/8 produced the most intense geomagnetic effects since the Halloween event of 2003. The resulting extreme solar storm is thought to be the consequence of multiple interacting coronal mass ejections (CMEs). Notably, this AR exhibits exceptionally rapid magnetic flux emergence. The eruptions on which we focus all occurred along collisional polarity inversion lines (PILs) through collisional shearing during a three-day period of extraordinarily high flux emergence (∼1021 Mx h−1). Our key findings reveal how photospheric magnetic configurations in eruption sources influence solar superstorm formation and geomagnetic responses, and link exceptionally strong flux emergence to sequential homologous eruptions: (1) We identified the source regions of seven halo CMEs that were distributed primarily along two distinct PILs. This distribution suggests two groups of homologous CMEs. (2) The variations in the magnetic flux emergence rates in the source regions are correlated with the CME intensities. This might explain the two contrasting cases of complex ejecta that are observed at Earth. (3) Our calculations of the magnetic field gradients around the CME source regions show strong correlations with eruptions. This provides crucial insights into solar eruption mechanisms and enhances our prediction capabilities for future events.
Der Einfluss lokaler Applikation von Pfefferminze und Kälte auf die Schmerzintensität der Shuntpunktion bei Hämodialysepatienten
Authors: Wiederhold Dietmar
Published: November 2024

Dialysepatienten sind über 300-mal im Jahr einer schmerzhaften Punktion des Shunts ausgesetzt. Mehr als 50 % der Patienten berichten über Schmerzen an der Einstichstelle, die unangenehme Gefühle auslösen und langfristig die Lebensqualität negativ beeinflussen können.
Expert Opinion for Defining a Severe Bleeding Phenotype to Guide Prophylaxis in Patients with Nonsevere Hemophilia
Authors: Pfrepper Christian , Ettingshausen Carmen Escuriola , Klamroth Robert , Oldenburg Johannes , Olivieri Martin
Published: November 2024

Prophylaxis is the standard of care for patients with severe hemophilia, patients with moderate hemophilia, or those with another congenital bleeding disorder that is associated with a severe bleeding phenotype and/or a high risk of spontaneous life-threatening bleeding. Patients with nonsevere hemophilia (factor VIII [FVIII] ≥ 1%) may also have a bleeding phenotype that requires prophylaxis. To date, however, there are no clear criteria as to when prophylaxis is indicated in these patients. Also, the term “severe bleeding phenotype (SBPT)” is neither included in the definitions of the International Society on Thrombosis and Haemostasis (ISTH) nor specified in the World Federation of Hemophilia (WFH) guidelines. Based on our personal experience and available evidence, we propose the criteria we use to define an SBPT and when we consider offering prophylaxis in patients with nonsevere hemophilia. Our proposals can be the basis for discussions in the community about the assessment of SBPT and the initiation of prophylaxis in patients with nonsevere hemophilia without inhibitors.
Auswirkungen der COVID-19-Pandemie auf die Zuweisungen in die nephrologische Hochschulambulanz des Universitätsklinikums Jena
Authors: Ruhe Johannes , Koch Annegret , Koch Annegret , Wolf Gunter
Published: November 2024

In einer retrospektiven Datenerhebung gingen wir der Fragestellung nach, inwieweit sich die Patientenzahlen und Arzt-Patienten-Kontakte der nephrologischen Hochschulambulanz am Universitätsklinikum Jena während und nach der COVID-19-Pandemie verändert haben. Während stationäre Fallzahlen rückläufig waren, zeigte sich, dass in den beiden präpandemischen Jahren 2018 und 2019 die Fallzahlen auf vergleichbarem Niveau waren, während der Pandemie (insbesondere von 2020 auf 2021) anstiegen und dieser ansteigende Trend bis 2023 anhielt. Dies bringt Herausforderungen in der Patientenbetreuung – insbesondere in der Logistik und im Ressourcen- sowie Personalmanagement – mit sich. Parallel dazu verzeichnen wir eine Verdoppelung der hausärztlichen Zuweisungen von 2018–2021. Der führende Grund der Zuweisung bestand 2018/2019 in ergänzender Hypertoniediagnostik und -therapie sowie der Mitbetreuung eines Kreatininanstiegs bei bekannter sekundärer (hypertensiver, diabetischer oder vaskulärer) Nephropathie. Hingegen wurden während der Pandemie Patienten vermehrt zur Abklärung und Mitbetreuung einer neuen Proteinurie oder (Mikro-)Hämaturie sowie zur Mitbehandlung vermuteter primärer Glomerulonephritisformen überwiesen. Als Hauptursache ist möglicherweise das verbesserte Screening auf Proteinurie per Spontanurindiagnostik im hausärztlichen Setting und in diesem Zuge auch die erhöhte Detektion einer Erythrozyturie zu sehen. Zudem steigt die Rate an Patienten mit Diabetes mellitus und arterieller Hypertonie trotz moderner Therapiemethoden stetig an. Mittel- bis langfristig müssen bisherige Strukturen adaptiert werden, um den steigenden Patientenzahlen mit bisheriger Qualität gerecht zu werden.
Hygiene & Nachhaltigkeit in der Nierenersatztherapie
Authors: Girndt Matthias , Nolte Holger , Sommer Falk
Published: November 2024

Das Gesundheitswesen benötigt in großem Umfang Energie und Rohstoffe und erzeugt große Mengen an Abfall. Die chronische Dialyse gehört zu den besonders ressourcenintensiven Versorgungsbereichen. Strom- und Wasserverbrauch sowie plastikbasierte Einmalmaterialien, die bisher vor allem als Kostenfaktoren gesehen wurden, tragen sehr erheblich zum CO2-Fußabdruck dieses Bereiches bei. Weltweit gibt es daher derzeit Bestrebungen, organisatorisch und konstruktiv Effizienzreserven zu heben. Gerade bei der Dialyse muss dabei jedoch akribisch darauf geachtet werden, die Sicherheit und Behandlungsqualität nicht zu gefährden.
Bidirectional scanning acquisition of inter-satellite laser links for space gravitational wave detection mission
Authors: Liu Xianda , Meng Yunhe
Published: November 2024

Space gravitational wave detection requires establishing laser links between distributed spacecraft for interferometry. Inter-satellite laser link acquisition is an essential step in this process. Considering the spacecraft’s miniaturization and reliability, a bidirectional scanning acquisition method is proposed using only field emission electric propulsion and quadrant photodetector. This method does not require additional acquisition sensors and actuators. To improve efficiency while ensuring the acquisition success rate, a constant angular velocity Archimedean spiral scanning guidance law is proposed, and the critical parameters that influence acquisition time and success rate are analyzed. Monte Carlo simulations show that the method can ensure an acquisition success rate of over 90%. Compared with constant linear velocity Archimedean spiral scanning, this method can reduce the acquisition time required to achieve the same success rate by 15%.
Forming a database to study reversed magnetic shear from the National Spherical Torus eXperiment using machine learning
Authors: Uzun-Kaymak I. U. , Foley E. L. , Galante M. E. , Levinton F. M.
Published: November 2024

Achieving a long-lived reversed magnetic shear (RMS) target plasma in the National Spherical Torus eXperiment Upgrade will require developing various sustainment scenarios. To help with the ongoing plasma control efforts, the development of a new analysis for the motional Stark effect (MSE) diagnostic using a machine learning algorithm, namely, MSE-ML, is described. MSE-ML will be used to identify patterns during RMS discharges, some of which suffer magnetohydrodynamic (MHD) events resulting in current redistribution and monotonic q-profiles. A database consisting of q and magnetic shear profiles is being constructed primarily based on the existing National Spherical Torus eXperiment data with equilibrium reconstructions constrained by the magnetic field pitch angle profile measured using the multi-channel MSE diagnostic. An unsupervised k-means clustering of the data is developed to study the RMS formation as a function of time. The initial clustering from the q-profiles shows significant differences in both amplitude and the duration of the RMS period. As a goal, the clustering results that detect and distinguish shots with substantial and sustained RMS are to be used as a preprocessing step in a supervised algorithm to identify the underlying conditions that lead to long-lasting improved confinement with RMS. Another aim of the MSE-ML study is to identify precursors of RMS-destroying MHD events in either derived data such as the q-profile or directly measured data such as the magnetic field pitch angle profile.
Characterization of liquid-thickness distribution in micropores on elastic surface under sliding and pressurizing conditions
Authors: Ichikawa Yoshiyasu , Shinozuka Rikuto , Sugisawa Shinya , Hatano Tatsuhiko , Kaji Yoshio , Kuwayama Isao , Motosuke Masahiro
Published: November 2024

To improve the performance of studless tires on ice surfaces, the mechanism of liquid film removal must be elucidated. In this study, an experimental system is developed to simulate the running conditions of a studless tire, and the microscopic liquid film flow generated between the rubber surface and glass is observed to evaluate the liquid thickness distribution. Liquid film removal by micropores on foamed rubber samples is investigated by visualizing the liquid thickness in the micropores. The proposed system enables variations in the pressure and sliding velocity between the rubber and glass. The liquid thickness in the micropores is measured using laser-induced fluorescence, and the effects of pressure and sliding velocity on the thickness are examined. Water penetrates the micropores on the rubber sample surface, and different liquid thicknesses are obtained for each pore. The amount of liquid penetrating the pores is affected to a greater extent by the sliding velocity than by the pressure. Therefore, liquid penetration is more strongly influenced by the hydrodynamic effect of the increasing inertia of the liquid under high sliding velocities than by the elastic deformation of the pore.
High-throughput structural screening and property study of noncentrosymmetric superconductors in Th-based ZrNiAl-like compounds
Authors: Yang Fuqiang , Song Jiexi , Qin Yanqing , Yang Xiaoguang , Cao Chongde
Published: November 2024

Noncentrosymmetric superconductors (NCSs) are emerging as potential materials for the investigation of nontraditional phenomena, including both the presence of a spin-singlet pairing configuration and the occurrence of a spin-triplet pairing configuration, as well as the manifestation of topological superconductivity. In this work, we constructed a high-throughput theoretical design and performed a computational screening of Th-based NCSs with ZrNiAl-like structures based on the first principles method. Through systematic stability evaluations, we expanded the range of Th-based ZrNiAl-like compounds with superior stability to 45 materials. In this group of substances, we have pinpointed 17 prospective entities exhibiting notable band separation in the vicinity of the Fermi level. Electron–phonon coupling calculations indicated that 14 of these compounds are superconducting. By performing an analysis of electronic properties, we proposed that ThAlRu and ThAlOs are two promising NCSs in this family. This work may aid in the exploration of the design and synthesis of Th-based ZrNiAl-like materials, leading to the discovery of more NCSs with unique superconducting properties.
TCAD-based investigation of 1/f noise in advanced 22 nm FDSOI MOSFETs
Authors: Khedgarkar Prabhat , Ganeriwala Mohit D. , Duhan Pardeep
Published: November 2024

In this work, the mechanistic insights behind low-frequency noise (LFN) of the advanced ultrathin body and buried oxide fully depleted silicon-on-insulator based metal–oxide–semiconductor field effect transistor (MOSFET) are unveiled. The gate voltage-induced noise power spectral density (SVG) is inversely proportional to frequency f (i.e., SVG∝1/fγ, γ∼ 1 is the frequency exponent) for nMOSFET and pMOSFET. Detailed numerical simulations are performed and well calibrated to reported SVG vs f characteristics. Simulation results are consistent with the reported experimental observations. We demonstrate that LFN is caused by the charge carrier number fluctuation mechanism, which is originated by trapping and de-trapping of channel charge carriers via. bulk traps (from oxygen vacancies) in the hafnium dioxide (HfO2) layer, but not through traps at the silicon dioxide (SiO2)/channel interface. This work therefore explains the similar magnitude of SVG in both nMOSFET and pMOSFET observed experimentally and further suggests that oxygen vacancies inside gate oxides are critical to suppress the low-frequency noise in emerging high-k based MOSFETs.
Evaluation of degradation phenomena in the electric potential distribution inside organic light-emitting diodes by electron holography
Authors: Sasaki Yusei , Anada Satoshi , Yoshimoto Noriyuki , Yamamoto Kazuo
Published: November 2024

Understanding the intrinsic degradation processes of organic light-emitting diodes is necessary to improve their lifetimes. This intrinsic degradation is typically caused by carrier injection at the interface between the hole transport layer (HTL) and the emissive layer (EML). However, revealing the charge behavior in this local region with a high spatial resolution remains challenging. Thus, this study employed electron holography, a transmission electron microscopy (TEM) technique, to measure the nanometer scale potential distribution inside an OLED composed of N,N′-di-[(1-naphthyl)-N,N′-diphenyl]-(1,1′-biphenyl)-4,4′-diamine (α-NPD) and tris-(8-hydroxyquinoline)aluminum (Alq3) that was degraded via continuous voltage application. The α-NPD and Alq3 functioned as the HTL and EML, respectively. The degraded OLED was found to exhibit several potential distributions, depending on the local positions from which the TEM samples were lifted out of the same bulk sample. The distributions included (i) formation of a potential valley at the α-NPD/Alq3 interface, (ii) disappearance of electric fields within the organic layers, and (iii) similar distribution to original before degradation. We suggest that the degradation was caused by charge accumulation, cationization of Alq3, and local failures. Thus, this study revealed the influence of electric degradation at the nanometer scale because of charge injection to the α-NPD/Alq3 interface. Electron holographic degradation analysis near the HTL/EML interface is expected to aid in the development of design guidelines for preventing device degradation and thus extend device lifetime.
Surrogate modeling of multi-dimensional premixed and non-premixed combustion using pseudo-time stepping physics-informed neural networks
Authors: Cao Zhen , Liu Kai , Luo Kun , Wang Sifan , Jiang Liang , Fan Jianren
Published: November 2024

Physics-informed neural networks (PINNs) have emerged as a promising alternative to conventional computational fluid dynamics (CFD) approaches for solving and modeling multi-dimensional flow fields. They offer instant inference speed and cost-effectiveness without the need for training datasets. However, compared to common data-driven methods, purely learning the physical constraints of partial differential equations and boundary conditions is much more challenging and prone to convergence issues leading to incorrect local optima. This training robustness issue significantly increases the difficulty of fine-tuning PINNs and limits their widespread adoption. In this work, we present improvements to the prior field-resolving surrogate modeling framework for combustion systems based on PINNs. First, inspired by the time-stepping schemes used in CFD numerical methods, we introduce a pseudo-time stepping loss aggregation algorithm to enhance the convergence robustness of the PINNs training process. This new pseudo-time stepping PINNs (PTS-PINNs) method is then tested in non-reactive convection–diffusion problem, and the results demonstrated its good convergence capability for multi-species transport problems. Second, the effectiveness of the PTS-PINNs method was verified in the case of methane–air premixed combustion, and the results show that the L2 norm relative error of all variables can be reduced within 5%. Finally, we also extend the capability of the PTS-PINNs method to address a more complex methane–air non-premixed combustion problem. The results indicate that the PTS-PINNs method can still achieve commendable accuracy by reducing the relative error to within 10%. Overall, the PTS-PINNs method demonstrates the ability to rapidly and accurately identify the convergence direction of the model, surpassing traditional PINNs methods in this regard.
Semiclassical instanton theory for reaction rates at any temperature: How a rigorous real-time derivation solves the crossover temperature problem
Authors: Lawrence Joseph E.
Published: November 2024

Instanton theory relates the rate constant for tunneling through a barrier to the periodic classical trajectory on the upturned potential energy surface, whose period is τ = ℏ/(kBT). Unfortunately, the standard theory is only applicable below the “crossover temperature,” where the periodic orbit first appears. This paper presents a rigorous semiclassical (ℏ → 0) theory for the rate that is valid at any temperature. The theory is derived by combining Bleistein’s method for generating uniform asymptotic expansions with a real-time modification of Richardson’s flux-correlation function derivation of instanton theory. The resulting theory smoothly connects the instanton result at low temperature to the parabolic correction to Eyring transition state theory at high-temperature. Although the derivation involves real time, the final theory only involves imaginary-time (thermal) properties, consistent with the standard version of instanton theory. Therefore, it is no more difficult to compute than the standard theory. The theory is illustrated with application to model systems, where it is shown to give excellent numerical results. Finally, the first-principles approach taken here results in a number of advantages over previous attempts to extend the imaginary free-energy formulation of instanton theory. In addition to producing a theory that is a smooth (continuously differentiable) function of temperature, the derivation also naturally incorporates hyperasymptotic (i.e., multi-orbit) terms and provides a framework for further extensions of the theory.
Numerical simulations for the flow-induced vibrations of tandem dual flexible circular cylinders
Authors: Wang Yuqi , Zhou Qiang , Xu Fuyou , Zhang Zhanbiao , Wang Xu
Published: November 2024

The three-dimensional large-eddy-simulation coupled with a mode superposition method was applied to numerically simulate the flow-induced vibrations (FIVs) of tandem dual flexible cylinders at Re = 1000 with three different spacing ratios (Sx/D = 2.5, 3.5, and 5, Sx is center-to-center spacing for tandem cylinders, and D is the diameter of the cylinder), corresponding to the reattachment flow, transition flow, and co-shedding flow regimes in stationary tandem cylinders, respectively. The effects of Sx/D on structural vibrations, flow fields, distributions of the surface pressures, and energy properties were investigated to reveal the mechanism for the FIV. Increasing Sx/D weakens the influence of the upstream cylinder on maximum response amplitudes and lock-in region for downstream cylinder. The wake patterns for tandem flexible cylinders are more complex compared to stationary or vibrated rigid tandem cylinders. The shielding effect reduces surface pressure on the downstream cylinder significantly when its vibrations are smaller, leading to a decrease in mean power as well. Furthermore, different mechanisms contribute to amplified FIV in downstream cylinders depending on Sx/D: when Sx/D = 2.5, the upstream vortices collide with the downstream cylinder's front surface and merge with the vortices generated by the downstream cylinder, increasing negative pressure on both front and rear surfaces of the downstream cylinders and promoting FIV; however when Sx/D =3.5 and 5, a binary vortex street forms behind the downstream cylinder without obvious negative pressures on its front surface, the dominant causes of FIV are primarily attributed to interactions among upstream and downstream vortices.
The impact of a variable-camber inlet guide vane on the performance of a highly loaded counter-rotating fan under variable working conditions
Authors: Sun Qi , Yao Ka , Wu Yan , Yan Rui
Published: November 2024

In this research, a variable-camber inlet guide vane (VIGV) is applied to a highly loaded counter-rotating fan for the first time at variable working conditions. Additionally, internal flow analysis of the highly loaded counter-rotating fan is performed to reveal the essential flow mechanism and determine its impact on overall performance. It is found that the through-flow capacity is improved with a decrease in the camber angle. At −10°VIGV, the through-flow capacity increases by 3.1% at the design speed, while the through-flow capacity is only increased by 0.7% at the low corrected speed. The main reason for this is that the through-flow capacity along the blade span of the high-pressure rotor can be increased at the design speed, while only part of the blade span can be increased at the low corrected speed. At the low corrected speed, with the increase in the camber angle, the isentropic efficiency can be effectively improved by the counter-rotating fan, and the isentropic efficiency increases by 1.43% at +20°VIGV. This is mainly due to the decrease in the camber angle reducing the low-pressure rotor's incidence angle along the blade span, which suppresses the flow separation of the low-pressure rotor's suction surface.
Electron transport in quasi-ballistic FETs subjected to a magnetic field
Authors: Yelisieiev M. , Kochelap V. A.
Published: November 2024

We report the study of quasi-ballistic electron transport in short FETs subjected to magnetic field. Spatial distributions of electron concentrations, velocities, Hall currents, and voltages in the short FET channels are determined. The basic properties of current–voltage characteristics of quasi-ballistic FETs in magnetic field are analyzed, among them the kink-like characteristics of the near-ballistic device. Peculiarities of magnetoresistance of such FETs are studied for low and high magnetic fields and different current regimes. For nonlinear current regimes, we revealed significantly larger magnetoresistance for the devices with higher ballisticity. Numerical estimates of studied effects are presented. We suggest that the found results contribute to the physics of short FETs and can be used for developing nanoscale devices for particular applications.
Arkypallidal neurons in the external globus pallidus can mediate inhibitory control by altering competition in the striatum
Authors: Giossi Cristina , Bahuguna Jyotika , Rubin Jonathan E. , Verstynen Timothy , Vich Catalina
Published: November 2024

Reactive inhibitory control is crucial for survival. Traditionally, this control in mammals was attributed solely to the hyperdirect pathway, with cortical control signals flowing unidirectionally from the subthalamic nucleus (STN) to basal ganglia output regions. Yet recent findings have put this model into question, suggesting that the STN is assisted in stopping actions through ascending control signals to the striatum mediated by the external globus pallidus (GPe). Here, we investigate this suggestion by harnessing a biologically constrained spiking model of the cortico-basal ganglia-thalamic (CBGT) circuit that includes pallidostriatal pathways originating from arkypallidal neurons. Through a series of experiments probing the interaction between three critical inhibitory nodes (the STN, arkypallidal cells, and indirect pathway spiny projection neurons), we find that the GPe acts as a critical mediator of both ascending and descending inhibitory signals in the CBGT circuit. In particular, pallidostriatal pathways regulate this process by weakening the direct pathway dominance of the evidence accumulation process driving decisions, which increases the relative suppressive influence of the indirect pathway on basal ganglia output. These findings delineate how pallidostriatal pathways can facilitate action cancellation by managing the bidirectional flow of information within CBGT circuits.
Electronic structure of 2(5H)-thiophenone studied by UPS and soft x-ray spectroscopy
Authors: Plekan Oksana , Ponzi Aurora , Grazioli Cesare , Coreno Marcello , de Simone Monica , Morini Filippo , Bernes Elisa , Fronzoni Giovanna , Toffoli Daniele
Published: November 2024

The electronic structure of 2(5H)-thiophenone in the gas phase was investigated by ultraviolet photoelectron spectroscopy and x-ray photoemission spectroscopy (XPS) and near edge x-ray absorption fine structure (NEXAFS) spectroscopy at the C 1s, O 1s, and S 2p edges. All assignments of the experimental results are supported by both ab-initio electron propagator outer-valence Green’s function (OVGF) calculations for the valence photoemission bands and density functional theory (DFT) and relativistic time dependent DFT calculations for the core levels XPS and NEXAFS spectra. Overall good agreement between experiment and theory is observed; this is especially true for core electron excitations which has permitted an unambiguous assignment of the observed spectral features in terms of single-particle excitations to virtual molecular orbitals. The assignment of the valence band spectra based on OVGF calculations, although satisfactory, points to the importance of electron correlations effects that partially break the single particle picture of ionization.
Microstructural and mechanical properties study of various lattice structures of SS316L-CNTs nano composites fabricated through additive manufacturing
Authors: Yadav B N , Alfantazi Akram , Alazemi Abdullah A , Mandal Ajay , Lin Pai-Chen , Huang Pei-Chen , Yeh De-Yi , Liu De-Shin
Published: November 2024

In this work, various lattice structures, such as face-centered (FCC), body-centered (BCC), gyroid (GD), and bare gyroid (BGD (without CNTs)) with four different porosities (60%, 70%, 80%, and 90%), were prepared through the selective laser melting additive manufacturing process. Stainless steel 316 l alloy was utilized as the base material, while 0.2 wt.% functionalized carbon nanotubes (CNTs) were employed as reinforcement. The uniform dispersion of CNTs was analyzed using FESEM, TEM, and Raman spectroscopy. The results indicated that the plateau stress increases with the addition of CNTs, irrespective to the lattice structure. Also, in case of relative density the plateau stress increases with increasing the relative density. Similarly, the energy absorption also increases with the addition of CNTs regardless to the lattice structure. However, with increasing relative densities, energy absorption increases up to the 30% deformation regardless to the lattice structure and followed order was the BCC > FCC > GD > BGD.
Numerical simulation of cathode-spot crater and droplet formation with linear and circular motion process
Authors: Wang Lijun , Wang Cong , Gao Hexiao , Zhang Runming , Xie Yiduo
Published: November 2024

In this paper, a three-dimensional cathode spot erosion model is proposed to study the development of cathode spot motion process on the surface of copper cathode. The formation and development process of cathode spots motion without external magnetic field is studied. In this model, energy flux density, pressure, and current value are considered as external parameters. The simulation results compared the cathode spot ablation trajectories and temperature distribution under different motion forms and motion velocities. The results indicated that during the spots expansion process, the flow of liquid metal will form a convex structure on the surface of the cathode and a hollow structure inside the cathode. Comparing different motion types, the annular motion significantly increased the roughness of the cathode surface. With the increase of the speed of spots movement, the interaction between the craters is significantly weakened, which will reduce the temperature and the roughness of the cathode surface. The simulation results are consistent with the experimental results.
Negative piezoelectricity in quasi-two/one-dimensional ferroelectrics
Authors: Ding Ning , Dong Shuai
Published: November 2024

In recent years, the investigation of low-dimensional ferroelectrics has attracted great attention for their promising applications in nano devices. Piezoelectricity is one of the most core properties of ferroelectric materials, which plays an essential role in micro-electromechanical systems. Very recently, anomalous negative piezoelectricity has been predicted/discovered in many quasi-two-dimensional layered ferroelectric materials. In this Topical Review, we will briefly introduce the negative piezoelectricity in quasi-two/one-dimensional ferroelectrics, including its fundamental concepts, typical materials, theoretical predictions, as well as experimental phenomena. The underlying physical mechanisms for negative piezoelectricity are divergent and vary case by case, which can be categorized into four types: first, the soft van der Waals (vdW) layer is responsible for the volume shrinking upon pressure while the electric dipoles are from the non vdW layer; second, the noncollinearity of local dipoles creates a ferrielectricity, which leads to orthogonal ferroelectric and antiferroelectric axes; third, the electric dipoles come from interlayer/interchain couplings, which can be enhanced during the volume shrinking; fourth, the special buckling structure contributes to local dipoles, which can be enhanced upon pressure. In real materials, more than one mechanism may work together. Finally, future directions of negative piezoelectricity and their potential applications are outlined.
Enhanced energy storage performance in BaZrxTi1–xO3 lead-free ferroelectrics near phase transitions
Authors: Vu Ba-Hieu , Dang Ha Thi , Dinh Van-Hai , Lich Le Van
Published: November 2024

The present study explores the energy storage properties of BaZr
x
Ti

1
−
x

O3 through phase-field modeling, focusing on the impact of composition and temperature on energy storage performance. The obtained results reveal a variety of polarization phases and configurations based on Zr compositions and temperatures. A detailed phase diagram for temperature-composition of BaZr
x
Ti

1
−
x

O3 is established, closely aligning with experimental measurements. Variations in Zr content and temperature have a significant impact on the polarization-electric field (P − E) response, influencing the energy storage properties. Calculations of energy storage properties are derived from the P − E response. In addition, a thorough diagram is developed to illustrate the discharge energy density of BaZr
x
Ti

1
−
x

O3 as a function of temperature and composition. Notably, high discharge energy density is achievable near the Curie temperature, corresponding to the transition from ferroelectric to paraelectric phase. Furthermore, the present study emphasizes the importance of the disparity between maximum and remanent polarization, as well as the electric field-dependent effective permittivity, in determining the discharge energy density.
Challenges faced by women and persons excluded because of their ethnicity and race in physics learning environments: review of the literature and recommendations for departments and instructors
Authors: Maries Alexandru , Li Yangquiting , Singh Chandralekha
Published: November 2024

Physics, as a discipline, has long struggled with pervasive stereotypes and biases about who is capable and can excel in it. Physics also ranks among the least diverse among all science, technology, engineering, and mathematics (STEM) disciplines, often cultivating and fostering learning environments that lack inclusivity and equity. Moreover, stereotypes about brilliance, inequitable physics learning environments and the overall physics culture not only impact the experiences and outcomes of students who major in physics, but also those from other STEM disciplines who must take physics courses. Here we undertake a narrative review, delving into research concerning diversity, equity, and inclusion within undergraduate physics education. We concentrate on the experiences of women and persons excluded due to their ethnicity or race in physics, aiming to shed light on the alarming current situation. The review begins with a few concrete examples of exclusionary experiences that research shows are common for women in physics and can reduce their interest or motivation to pursue a physics major. Then, we provide our conceptualization of equity in physics learning environments and describe the frameworks informing the perspective taken in the review. We then discuss issues related to inequities in physics learning environments, including but not limited to inequities in academic performance, participation, and persistence in physics, as well as psychological factors such as physics self-efficacy, perceived recognition, social belonging, mindset beliefs, and others. We also review research on factors commonly associated with the lack of diversity, equity, and inclusion in physics including the lack of role models, stereotypes associating physics with brilliance, and the overall prototypical culture of physics. We emphasize that addressing these systemic issues in physics requires a holistic approach. We conclude with a list of recommendations for physics departments and instructors on how they can play an important role in transforming the physics culture and making the learning environments equitable and inclusive so that all students can engage in learning physics and enjoy it while feeling supported.
Asynchronous quantum repeater using multiple quantum memory
Authors: Li Chen-Long , Yin Hua-Lei , Chen Zeng-Bing
Published: November 2024

A full-fledged quantum network relies on the formation of entangled links between remote location with the help of quantum repeaters. The famous Duan–Lukin–Cirac–Zoller quantum repeater protocol is based on long distance single-photon interference (SPI), which not only requires high phase stability but also cannot generate maximally entangled state. Here, we propose a quantum repeater protocol using the idea of post-matching, which retains the same efficiency as the SPI protocol, reduces the phase-stability requirement and can generate maximally entangled state in principle. We also outline an implementation of our scheme based on the Kerr nonlinear resonator. Numerical simulations show that our protocol has its superiority by comparing with existing protocols under a generic noise model and show the feasibility of building a large-scale quantum communication network with our scheme. We believe our work represents a crucial step towards the construction of a fully-connected quantum network.
Design and experimental evaluation of a compact inchworm piezoelectric actuator with bridge-type displacement amplification mechanism
Authors: Li Hailong , Li Yuntao , Deng Shaolong , Shan Junhui , Bai Deen
Published: November 2024

Miniaturization is an important direction in piezoelectric actuator research, with related efforts focusing on reducing structural complexity and simplifying guiding mechanisms. However, some actuators experience backward movement after miniaturization design. There remains significant room for improvement in mechanism configuration and the design of flexible amplification mechanisms to further reduce actuator size. In this paper, a compact inchworm actuator with bridge-type displacement amplification mechanism (BTDAM) is proposed, which does not require an additional guiding mechanism and adopts a three-dimensional packaging approach with high space utilization and a compact amplification mechanism. Because the output capacity of the BTDAM significantly impacts the operating performance of the actuator, mathematical modeling and simulation analysis are conducted. Compared with the experimental results of the amplification ratio of the BTDAM, the error of the theoretical model was 5.05%, and that of the finite element method analysis was 9.1%. The dimensions of the prototype are 23 × 23 × 19 mm, and it weighs 23 g. The test results indicate that the proposed actuator can achieve stable stepping motion without backward movement. Under a voltage of 75 V, the proposed actuator achieves a maximum motion speed of 384 μm s−1 and a maximum output force of 1.7 N. With its compact structure and light weight, the proposed actuator shows promising application prospects in the aerospace and bioengineering fields.
Single motor driven soft actuator design based on nonuniform sheering auxetic structure
Authors: Xiang Zezhi , Chen Shiye , Han Yafeng , Lu Jiping , Tang Shuiyuan , Fan Hongli , Wang Haoren , Xia Yuhan , Gong Chenglong , Wang Run , Tang Le
Published: November 2024

Grasping functionality is one of the core functionalities that a manipulator needs to possess. Traditional rigid manipulators are typically composed of rigid materials. However, when dealing with objects of complex shapes, irregular surfaces, or soft materials, rigid manipulators often face challenges in effectively grasping and stably holding objects due to their rigidity, which can lead to damage or failure. To address these issues, constructing manipulators using soft actuators can be highly advantageous. In most current research, soft actuators are typically composed of flexible materials and fluids, which can result in highly complex dynamic behaviors and nonlinear characteristics. This complexity makes precise modeling and control of soft actuators more challenging, necessitating the use of advanced control algorithms and techniques to mitigate nonlinear effects. In this study, we first establish a mathematical model for the torsional and bending deformations of non-uniform shearing-auxetic structures. Subsequently, we validate the reliability of the mathematical model through simulation. Finally, we design a soft actuator that requires only single-motor control, which is based on the structural design of non-uniform shearing-auxetic structures. This type of soft actuator not only simplifies control aspects but also facilitates practical modeling and manufacturing processes. Moreover, it is capable of achieving spiral grasping functionality.
Optimization of superconducting niobium nitride thin films via high-power impulse magnetron sputtering
Authors: Horne Hudson T , Hugo Collin M , Reid Brandon C , Santavicca Daniel F
Published: November 2024

We report a systematic comparison of niobium nitride thin films deposited on oxidized silicon substrates by reactive DC magnetron sputtering and reactive high-power impulse magnetron sputtering (HiPIMS). After determining the nitrogen gas concentration that produces the highest superconducting critical temperature for each process, we characterize the dependence of the critical temperature on film thickness. The optimal nitrogen concentration is higher for HiPIMS than for DC sputtering, and HiPIMS produces higher critical temperatures for all thicknesses studied. We attribute this to the HiPIMS process enabling the films to get closer to optimal stoichiometry before beginning to form a hexagonal crystal phase that reduces the critical temperature, along with the extra kinetic energy in the HiPIMS process improving crystallinity. We also study the ability to increase the critical temperature of the HiPIMS films through the use of an aluminum nitride buffer layer and substrate heating.
Rotation of self-generated electromagnetic fields by the Nernst effect and Righi–Leduc flux during an intense laser interaction with targets
Authors: Zhao Ziqi , Yang Xiaohu , Chen Zehao , Zhang Guobo , Ma Yanyun
Published: November 2024

The effect of an external magnetic field on the evolution of the self-generated electromagnetic field during laser ablation is investigated by using the Vlasov–Fokker–Planck simulations. It is found that the self-generated field is rotated and distorted under an external magnetic field, and for highly magnetized plasma, the rotation of the electric field becomes stable after the laser ablation. The theoretical analysis indicates that the rotation and tortuosity are primarily attributed to the advection of the Nernst effect and the Righi–Leduc (RL) flux. The curl of the self-generated field increases with the Hall parameter

χ

e

and reaches a peak at

χ

e

=
0.075

, then it decreases with the

χ

e

continuous increase. As the Hall parameter increases, the RL flux contributes more than 60% to the rotation of the electric field. Furthermore, the distortion of the electric field continues to rotate after the laser ablation due to the cross-gradient Nernst transport. These findings provide theoretical references for the evolution of the self-generated electromagnetic field in laser-driven magnetized plasmas.