bluuebunny/crossref_metadata_2025 huggingface dataset:
Infection-induced extracellular vesicles evoke neuronal transcriptional and epigenetic changes
Authors: Tedford Ellen , Badya Norhidayah Binti , Laing Conor , Asaoka Nozomi , Kaneko Shuji , Filippi Beatrice Maria , McConkey Glenn Alan
Published: April 2023

Infection with the protozoan Toxoplasma gondii induces changes in neurotransmission, neuroinflammation, and behavior, yet it remains elusive how these changes come about. In this study we investigated how norepinephrine levels are altered by infection. TINEV (Toxoplasma-induced neuronal extracellular vesicles) isolated from infected noradrenergic cells down-regulated dopamine ß-hydroxylase (DBH) gene expression in human and rodent cells. Here we report that intracerebral injection of TINEVs into the brain is sufficient to induce DBH down-regulation and distrupt catecholaminergic signalling. Further, TINEV treatment induced hypermethylation upstream of the DBH gene. An antisense lncRNA to DBH was found in purified TINEV preparations. Paracrine signalling to induce transcriptional gene silencing and DNA methylation may be a common mode to regulate neurologic function.
An AI based classifier model for lateral pillar classification of Legg–Calve–Perthes
Authors: Soydan Zafer , Saglam Yavuz , Key Sefa , Kati Yusuf Alper , Taskiran Murat , Kiymet Seyfullah , Salturk Tuba , Aydin Ahmet Serhat , Bilgili Fuat , Sen Cengiz
Published: April 2023

We intended to compare the doctors with a convolutional neural network (CNN) that we had trained using our own unique method for the Lateral Pillar Classification (LPC) of Legg–Calve–Perthes Disease (LCPD). Thousands of training data sets are frequently required for artificial intelligence (AI) applications in medicine. Since we did not have enough real patient radiographs to train a CNN, we devised a novel method to obtain them. We trained the CNN model with the data we created by modifying the normal hip radiographs. No real patient radiographs were ever used during the training phase. We tested the CNN model on 81 hips with LCPD. Firstly, we detected the interobserver reliability of the whole system and then the reliability of CNN alone. Second, the consensus list was used to compare the results of 11 doctors and the CNN model. Percentage agreement and interobserver analysis revealed that CNN had good reliability (ICC = 0.868). CNN has achieved a 76.54% classification performance and outperformed 9 out of 11 doctors. The CNN, which we trained with the aforementioned method, can now provide better results than doctors. In the future, as training data evolves and improves, we anticipate that AI will perform significantly better than physicians.
Analyzing drop coalescence in microfluidic devices with a deep learning generative model
Authors: Zhu Kewei , Cheng Sibo , Kovalchuk Nina , Simmons Mark , Guo Yi-Ke , Matar Omar K. , Arcucci Rossella
Published: April 2023

Predicting drop coalescence based on process parameters is crucial for experimental design in chemical engineering.
An efficient metal-free desulfurization strategy promoted by Togni-II reagent
Authors: Zhang Jun , Liu Haiyun , Teng Shuang , Liao Zhiwen , Meng Lingkui , Wan Qian , Dong Suwei
Published: April 2023

Desulfurization is a versatile synthetic tool in organic synthesis, particularly in peptide chemistry, where it offers an effective conversion strategy for compounds that contain mercaptan groups.
Visible light/copper catalysis enabled alkylation of silyl enol ethers with arylsulfonium salts
Authors: Cui Wenwen , Guo Guoju , Wang Yifei , Song Xiuyan , Lv Jian , Yang Daoshan
Published: April 2023

A photocatalytic protocol for the site-selective alkylation of silyl enol ethers with arylsulfonium salts giving access to aryl alkyl thioethers has been realized.
A phosphatase-recruiting bispecific antibody-aptamer chimera for enhanced suppression of tumor growth
Authors: Li Wei , Lu Weihua , Liu Zhen
Published: April 2023

A new strategy was developed for enhanced tumor suppression via simultaneous inhibition of both extra- and intra-cellular functions of mesenchymal epithelial transition (Met) receptor by a bispecific antibody-aptamer chimera.
Catalytic C–H alkynylation of benzylamines and aldehydes with aldimine-directing groups generated in situ
Authors: Zhou Jiao , Jiao Tenggang , Fu Qiang , Wang Jun , Lu Ji , Yang Lin , Wei Jun , Wei Siping , Cong Xuefeng , Hao Na
Published: April 2023

Iridium-catalysed regioselective C–H alkynylation of unprotected primary benzylamines and aliphatic aldehydes has been developed using in situ-installed aldimine directing groups.
Decomposition of triazole and 3-nitrotriazole upon low-energy electron attachment
Authors: Saqib Muhammad , Izadi Farhad , Isierhienrhien Leon U. , Ončák Milan , Denifl Stephan
Published: April 2023

The addition of the NO2 group to the triazole ring promotes the efficiency of electron attachment. Low-energy electrons decompose the molecule at sub-excitation energies.
Half-metallic and magnetic semiconductor behavior in CdO monolayer induced by acceptor impurities
Authors: Ponce-Pérez R. , Guerrero-Sanchez J. , Hoat D. M.
Published: April 2023

A doping approach is explored as a possible method to induce novel features in the CdO monolayer for spintronic applications.
A single-crystalline Co3O4 nanoparticle-assembled three-dimensional chain as an ultra-stable magnesium-ion battery cathode at different temperatures
Authors: Ding Qian , Han Tianli , Lin Xirong , Zhou Ting , Liu Jinyun , Zhang Huigang
Published: April 2023

A novel single-crystalline Co3O4 nanoparticle-assembled 3D chain is developed as a magnesium-ion battery cathode that displays an ultra-stable electrochemical performance at 45 °C, room temperature and −5 °C.
Correction: Characterisation of intergrowth in metal oxide materials using structure-mining: the case of γ-MnO2
Authors: Magnard Nicolas P. L. , Anker Andy S. , Aalling-Frederiksen Olivia , Kirsch Andrea , Jensen Kirsten M. Ø.
Published: April 2023

Correction for ‘Characterisation of intergrowth in metal oxide materials using structure-mining: the case of γ-MnO2’ by Nicolas P. L. Magnard et al., Dalton Trans., 2022, 51, 17150–17161, https://doi.org/10.1039/D2DT02153F.
ZIF-67@POM hybrid-derived unique willow-shaped two-dimensional Mo-CoP nanostructures as efficient electrocatalysts for the oxygen evolution reaction
Authors: Tang Yao , Zou Zijun , Wu Xingen , Zuo Pengfei , Wang Lei , Huang Guiwen , Zhu Jia , Zhong Shengliang
Published: April 2023

Mo-doped CoP have been preparedviaa simple precipitation method. The electrocatalyst shows an excellent performance for the OER with an overpotential of 290 mV at 10 mA cm−2and 100 h long-term durability.
Therapeutic vulnerabilities of cancer stem cells and effects of natural products
Authors: Reisenauer Keighley N. , Aroujo Jaquelin , Tao Yongfeng , Ranganathan Santhalakshmi , Romo Daniel , Taube Joseph H.
Published: April 2023

Residual tumor burden and chemotherapy-resistance point to a need for drug leads active toward cancer stem cells. Just as natural products have led the way for current treatments, the potential for novel applications of these molecules remains high.
Energy‐efficient multipath clustering with load balancing routing protocol for wireless multimedia sensor networks
Authors: Saleem Madyen Mohammad , Alabady Salah Abdulghani
Published: April 2023

Wireless multimedia sensor networks (WMSNs) has the capability of collecting scalar information, as well as multi‐media events like moving object tracking and traffic fatalities. Because energy in WMSNs is a constrained resource, several researchers offered cluster routing approaches, and most protocols generally do not offer an average resource usage of the network that is balanced and minimised. To address this issue, this paper proposes an Energy‐Efficient Multipath Clustering with Load Balancing Routing Protocol for WMSNs (EEMCL) to prolong the network lifetime. The suggested protocol, which segments the network into layers of clusters, would be implemented using multi‐hop. Sensing data from the sensor is transmitted to the sink by the main cluster heads in each layer, cooperating with the cluster heads in the upper layers. The proposed protocol improves energy dissipation, network life‐times, and network stability according to simulation results when compared with SEP, SEP‐E, and SEPFL protocols. The last node dead for the proposed protocol is at round 5833, 4027 for SEPFL, 2828 for SEP‐E, and 2325 for SEP.
Applying a temporal systematics model to vector Apodizing Phase Plate coronagraphic data: TRAP4vAPP
Authors: Liu Pengyu , Bohn Alexander J. , Doelman David S. , Sutlieff Ben J. , Samland Matthias , Kenworthy Matthew A. , Snik Frans , Birkby Jayne L. , Biller Beth A. , Males Jared R. , Morzinski Katie M. , Close Laird M. , Otten Gilles P. P. L.
Published: April 2023

Context. The vector Apodizing Phase Plate (vAPP) is a pupil plane coronagraph that suppresses starlight by forming a dark hole in its point spread function (PSF). The unconventional and non-axisymmetrical PSF arising from the phase modification applied by this coronagraph presents a special challenge to post-processing techniques.

Aims. We aim to implement a recently developed post-processing algorithm, temporal reference analysis of planets (TRAP) on vAPP coronagraphic data. The property of TRAP that uses non-local training pixels, combined with the unconventional PSF of vAPP, allows for more flexibility than previous spatial algorithms in selecting reference pixels to model systematic noise.

Methods. Datasets from two types of vAPPs are analysed: a double grating-vAPP (dgvAPP360) that produces a single symmetric PSF and a grating-vAPP (gvAPP180) that produces two D-shaped PSFs. We explore how to choose reference pixels to build temporal systematic noise models in TRAP for them. We then compare the performance of TRAP with previously implemented algorithms that produced the best signal-to-noise ratio (S/N) in companion detections in these datasets.

Results. We find that the systematic noise between the two D-shaped PSFs is not as temporally associated as expected. Conversely, there is still a significant number of systematic noise sources that are shared by the dark hole and the bright side in the same PSF. We should choose reference pixels from the same PSF when reducing the dgvAPP360 dataset or the gvAPP180 dataset with TRAP. In these datasets, TRAP achieves results consistent with previous best detections, with an improved S/N for the gvAPP180 dataset.
Phase transformation in the metallic reduction process of low-grade laterite nickel ores for ferronickel alloy production
Authors: Biao Tang , Bing Li , Hui Yang
Published: April 2023

The utilization of low-grade laterite ores has become necessary due to the intensive mining of high-grade nickel sulphide ores for a long time. In this study, metallic reduction roasting followed by magnetic separation to produce ferronickel alloy and abandon gangue minerals provides an effectively treatment for laterite ores. The experimental results indicate that ferronickel alloy containing more than 7.5% Ni with its recovery of 95% and more than 70% Fe with its recovery of 90% was produced successfully from the low-grade laterite ore. In the metallic reduction roasting process, the thermodynamic analysis displayed that the higher temperature promotes the conversion percentage of the oxidic nickel and iron to metallic nickel and iron. The ferronickel particle morphology with a liquid-solid growth and aggregation mechanism in the reduced laterite ore were investigated by SEM/EDS. XRD analysis revealed that the nickel laterite ore was transformed from hortonolite (MgOx · FeO2-x · SiO2) to forsterite (MgOx · CaOy · SiO2) during the metallic reduction process.
A Novel Method for Administering Epinephrine during Neonatal Resuscitation
Authors: Gu Hannah , Perl Juliana , Rhine William , Yamada Nicole K. , Sherman Jules , McMillin Alexandra , Halamek Louis P. , Wall James K. , Fuerch Janene H.
Published: April 2023

Objective This study aimed to determine if prefilled epinephrine syringes will reduce time to epinephrine administration compared with conventional epinephrine during standardized simulated neonatal resuscitation.

Study Design Timely and accurate epinephrine administration during neonatal resuscitation is lifesaving in bradycardic infants. Current epinephrine preparation is inefficient and error-prone. For other emergency use drugs, prefilled medication syringes have decreased error and administration time. Twenty-one neonatal intensive care unit nurses were enrolled. Each subject engaged in four simulated neonatal resuscitation scenarios involving term or preterm manikins using conventional epinephrine or novel prefilled epinephrine syringes specified for patient weight and administration route. All scenarios were video-recorded. Two investigators analyzed video recordings for time to epinephrine preparation and administration. Differences between conventional and novel techniques were evaluated using the Wilcoxon Signed Rank Tests.

Results Twenty-one subjects completed 42 scenarios with conventional epinephrine and 42 scenarios with novel prefilled syringes. Epinephrine preparation was faster using novel prefilled epinephrine syringes (median = 17.0 s, interquartile range [IQR] = 13.3–22.8) compared with conventional epinephrine (median = 48.0 s, IQR = 40.5–54.9, n = 42, z = 5.64, p < 0.001). Epinephrine administration was also faster using novel prefilled epinephrine syringes (median = 26.9 s, IQR = 22.1–33.2) compared with conventional epinephrine (median = 57.6 s, IQR = 48.8–66.8, n = 42, z = 5.63, p < 0.001). In a poststudy survey, all subjects supported the clinical adoption of prefilled epinephrine syringes.

Conclusion During simulated neonatal resuscitation, epinephrine preparation and administration are faster using novel prefilled epinephrine syringes, which may hasten return of spontaneous circulation and be lifesaving for bradycardic neonates in clinical practice.

Key Points
Pioneering production of carbon nanotube fibers for smart fabrics and the Internet of Things
Authors: Ikenson Ben
Published: April 2023

Study demonstrates easy-to-manufacture, low-cost, robust sensing platform
Producing next-generation transistors through doping
Authors: Green Leigh Ann
Published: April 2023

One method of doping transition metal dichalcogenides outshines other techniques.
The making of small but mighty antennas
Authors: Patrick Chris
Published: April 2023

Resistive elements that slowly vary in time enhance the operational bandwidth of small antennas to help overcome their performance limits.
Incorporating the Coulomb potential into a finite, unitary perturbation theory
Authors: Hoffmann Scott E.
Published: April 2023

We have constructed a perturbation theory to treat interactions that can include the Coulomb interaction, describing a physical problem that is often encountered in nuclear physics. The Coulomb part is not treated perturbatively; the exact solutions are employed. The method is an extension of the results presented in the work of Hoffmann [J. Math. Phys. 62, 032105 (2021)]. It is designed to calculate phase shifts directly rather than the full form of the wavefunctions in position space. We present formulas that allow for the calculation of the phase shifts to second order in the perturbation. The phase shift results to second order, for a short-range potential, were compared with the exact solution, where we found an error of third order in the coupling strength. A different model, meant as a simple approximation of nuclear scattering of a proton on helium-4 and including a Coulomb potential and a spherical well, was constructed to test the theory. The wavepacket scattering formalism of Hoffmann [J. Phys. B: At., Mol. Opt. Phys. 50, 215302 (2017)], known to give everywhere finite results, was employed. We found physically acceptable results and a cross section of the correct order of magnitude.
Discrete thermodynamic Cucker–Smale model with time-delay on a general digraph
Authors: Wu Chen , Dong Jiu-Gang
Published: April 2023

We study the discrete-time thermodynamic Cucker–Smale (TCS) model with a communication time-delay on a general digraph containing a spanning tree. In the TCS model, the mutual interactions not only are “mechanical” but also are affected by the “temperature effect.” It always takes time for information to be received between agents due to finite propagation speed effects. Transmission delays are inevitable and should be incorporated into flocking modeling. In this paper, we provide sufficient frameworks for flocking to the discrete TCS model, which are formulated in terms of initial configuration, network topology, and system parameters. In our proposed frameworks, we show that the TCS model exhibits exponential flocking convergence.
On the two-dimensional time-dependent anisotropic harmonic oscillator in a magnetic field
Authors: Patra Pinaki
Published: April 2023

A charged harmonic oscillator in a magnetic field, Landau problems, and an oscillator in a noncommutative space share the same mathematical structure in their Hamiltonians. We have considered a two-dimensional anisotropic harmonic oscillator with arbitrarily time-dependent parameters (effective mass and frequencies), placed in an arbitrarily time-dependent magnetic field. A class of quadratic invariant operators (in the sense of Lewis and Riesenfeld) have been constructed. The invariant operators (Î) have been reduced to a simplified representative form by a linear canonical transformation [the group Sp(4,R)]. An orthonormal basis of the Hilbert space consisting of the eigenvectors of Î is obtained. In order to obtain the solutions of the time-dependent Schrödinger equation corresponding to the system, both the geometric and dynamical phase-factors are constructed. A generalized Peres–Horodecki separability criterion (Simon’s criterion) for the ground state corresponding to our system has been demonstrated.
Drinfeld realization of the centrally extended psl(2|2) Yangian algebra with the manifest coproducts
Authors: Matsumoto Takuya
Published: April 2023

The Lie superalgebra psl(2|2) is recognized as a quite special algebra. In mathematics, it has the vanishing Killing form and allows for the three-dimensional central extension. In physics, it shows up as the symmetry of the one-dimensional Hubbard model and the asymptotic S-matrix of the anti-de Sitter/conformal field theory (AdS/CFT) correspondence. In this paper, we present the Drinfeld realization of the Yangian algebra associated with the centrally extended Lie superalgebra psl(2|2). Furthermore, we show that it possesses Hopf algebra structures, particularly the coproducts. The idea to prove the existence of manifest coproducts is as follows. First, we shall introduce them to Levendorskii’s realization, a system of a finite truncation of Drinfeld generators. Second, we show that Levendorskii’s realization is isomorphic to the Drinfeld realization by induction.
Analytical study of ionizing blast waves in atomic hydrogen
Authors: Gintrand A. , Bouquet S. , Michaut C.
Published: April 2023

The ionization effect on both the evolution and internal structure of a blast wave (BW) is determined in laboratory conditions. In a first step, the Rankine–Hugoniot equations describing the structure of the shock front together with the Saha equation modeling ionization are solved analytically in a consistent way for the conditions of a cold initial atomic hydrogen gas. In a second step, a simplified approach is used by introducing an effective adiabatic index γ* that takes into account ionization arising at the shock front. Finally, γ* is used as input data in the self-similar model derived formerly by Barenblatt to describe the structure and the dynamics of the ionizing BW. For the typical laboratory conditions of blast wave experiments, ionization achieves a hydrogen gas compression up to about 11 times at the shock front of the blast wave where a thin and dense shell forms. For such a compression, the value of the effective adiabatic index is γ*≃1.2 leading to a self-similar evolution of the BW where its radius R(t) varies according to R(t)∝tα* with α*≃0.33. This value of α* is lower than the adiabatic expansion stage α=2/5, where the total energy of the BW is conserved. Thus, ionization is found to act as a cooling effect at the shock front where a fraction of kinetic energy is absorbed to ionize the gas.
Miniaturized microsphere-assisted microscopy
Authors: Perrin Stephane , Pierron Robin , Gerard Philippe , Montgomery Paul , Lecler Sylvain
Published: April 2023

Microsphere-assisted microscopy is a sub-diffraction-limited imaging technique, which uses dielectric microspheres to collect the near-field information of an object. In this work, the bulk of the classical microsphere-based system is reduced by the simple introduction of a ball lens. The miniaturized imaging system has been designed and vertically assembled. Performance of the proposed dual-sphere system is quantified through numerical simulations and experiments. A theoretical impulse response with a full width at half maximum smaller than half of the wavelength is reached in air. As a proof of concept, 500-nm-period standard gratings and gold nanoparticles are observed without a classical objective, validating a sub-wavelength resolution with a high imaging quality and low aberrations over the field of view.
Molecular dynamics simulation for radiation response of Nb bicrystal having Σ 13, Σ 29, and Σ 85 grain boundary
Authors: Manna Mouparna , Pal Snehanshu
Published: April 2023

Nb is considered a promising candidate as a refractory element due to its high-temperature endurance, excellent thermal conductivity, and compatibility with liquid-metallic coolants in nuclear reactors. In the present study, radiation-based molecular dynamics numerical simulations were conducted in Σ 13, Σ 29, and Σ 85 symmetric tilt grain boundary models for pure Nb specimens. The stochastic high-energy collisions were modeled via large-scale atomic/molecular parallel simulator code to accurately investigate the radiation-induced defects generated in the order of picoseconds at the atomic level. The long-range embedded atom method potential and coulombic repulsive Ziegler–Biersack–Littmark potentials were smoothly overlaid for precise force-field interactions among Nb atoms. To investigate the ability to arrest the radiation-induced damage, the bi-crystal Nb specimens were irradiated at varying magnitudes of primary-knock-on atom (PKA) energies EPKA = 10 20, and 30 keV at temperature regimes 300, 600, and 900 K, respectively. The Frenkel pairs, complex linear defects, distribution of point defects as clusters, rate of defect annihilation, and temperature fluctuations within the displacement cascades of irradiated Nb specimens were comprehensively studied and reported. Here, the Nb-Σ 29 GB model survived with the lowest number of residual defects. Also, the recombination rate of the irradiated Nb specimens increases with the increase in temperature and PKA energy magnitude due to enhanced atomic mobility of the dislodged atoms. Hence, the bi-crystal Nb specimen can be favored for a radiation-tolerant material as structural components in next-generation reactors.
High-performance shim coil design and engineering optimization for use in an extremely high field superconducting magnet
Authors: Zheng Yijie , Wang Yaohui , Liu Feng , Yan Ming , Wang Qiuliang
Published: April 2023

The extremely high field has significant advantages in imaging quality and analyzing the fine structure of substances. However, its excellent performance requires the support of a higher-performance shim technique. In this paper, a novel structural design pattern of the shim coil for a 27 T extremely high field superconducting magnet is proposed. According to the contours of the stream function, we designed and optimized the shim coil pattern and engineering processing. The novel design was realized by using the contours as the centerline, and the wire spacing was controlled at 1 mm. The performance of the novel pattern was compared with those of alternative winding schemes. The results indicate that the novel design can improve coil performance, achieving higher fidelity and lower power dissipation.
Identification of phonon symmetry and spin-phonon coupling in van der Waals antiferromagnetic FePSe3
Authors: Xie Qiyun , Hu Shengjing , Hu Chengxiang , Sheng Qidi , Chen Limin , Zheng Jiajin , Wang Wei , Ma Ligang , Cheng Guofeng
Published: April 2023

For engineering of van der Waals antiferromagnetic material FePSe3 and expanding its potential technological promise in spintronic fields, a detailed knowledge of the underlying physics of vibrational phonon modes and their coupling with the spin degree of freedom are undoubtedly needed. In this work, by angle-resolved polarized Raman spectroscopy in corroboration with first-principles calculation, the Raman modes of bulk FePSe3 have been rationally assigned, which clarify the ambiguity about symmetry identification of some Raman-active modes in previous studies. Moreover, through detailed temperature-dependent Raman scattering experiments, the abnormal shift of the frequency, linewidth, and integrated intensity across the Néel temperature have been identified for phonon modes associating with a non-magnetic [P2Se6]4- cluster. This can be well explained with the assistance of the spin-phonon coupling mechanism that involves the variation of the d electron transfer with lattice vibration in magnetic materials. Our results are helpful for uncovering the rich physics in FePSe3 and also for enriching the further understanding of magnetic van der Waals materials down to the 2D limit.
Composition dependent charge retention in amorphous HfxAl1−xOy dielectric layers
Authors: Baik Seung Jae , Jeon SeHwan , Kim Geon Woong , Liu Gang
Published: April 2023

Charge trapping properties in dielectric materials serve as a ground principle in data storage devices called NAND flash. High-density nonvolatile storage requires deep trapping centers and localized trapped charge distribution. Current NAND flash technology relies on Si3N4 during the development history, and further development requires a higher dielectric constant material with compatible deep trapping centers and localized trapped charge profiles. In this work, charge trapping properties of HfxAl1−xOy dielectric layers with various compositions are investigated by modeling retention characteristics with trap energy and μτ product, where the former represents the trapping center depth and the latter represents the trapped charge profiles. Comparing the conventional Si3N4, HfxAl1−xOy dielectric layer with a low Hf content may improve long-term charge retention in NAND flash, while a localized trapped charge profile needs improvement to be compatible with Si3N4.
A new methodology for studying vortex dynamics based on point-contact spectroscopy
Authors: Hu Xiaomei , Zhang Fan , Hou Xingyuan , Dong Qingsong , Wang Suofu , Han Tao , Cheng Lixun , Cheng Feng , Ge Binghui , Long Mingsheng , Ding Fei , Zhu Xiangde , Shan Lei
Published: April 2023

Vortex dynamics has attracted tremendous attention for both fundamental physics and applications of type-II superconductors. However, methods to detect local vortex motion or vortex jump with high sensitivity are still scarce. Here, we fabricated soft point contacts on the clean layered superconductor 2H–NbSe2, which are demonstrated to contain multiple parallel micro-constrictions by scanning electronic microscopy. Andreev reflection spectroscopy was then studied in detail for the contacts. Differential conductance taken at fixed bias voltages was discovered to vary spontaneously over time in various magnetic fields perpendicular to the sample surface. The conductance variations become invisible when the field is zero or large enough, or parallel to the sample surface, which can be identified as the immediate consequence of vortex motion across a finite number of micro-constrictions. These results demonstrate point contact Andreev reflection spectroscopy to be a new potential way with a high time resolution to study the vortex dynamics in type-II superconductors.
Precise measurement of the work function of a hot CeB6
thermionic cathode through photoelectron yield spectroscopy using a tunable
pulsed laser
Authors: Magome Tamotsu , Togawa Kazuaki , Tanaka Hitoshi
Published: April 2023

Because the work function (WF) of the thermionic cathode of an electron gun is the primary factor for determining emission current density, the precise monitoring of the WF in actual operational conditions under high temperatures is essential for tracking the status of the cathode surface. We adjusted a theoretical model of quantum efficiency under high temperatures as proposed by R. H. Fowler to include the final energy state in the photoexcitation process. This modification is necessary for estimating the WF precisely with the measurement results obtained by photoelectron yield spectroscopy using a tunable pulsed laser in the wavelength range from 410 to 709 nm. As the first step of the investigation, we conducted WF measurements of a single-crystal CeB6 cathode, which is employed for the SACLA x-ray free-electron laser. The WF of the unused fresh CeB6 was 2.44 ± 0.02 eV at a high temperature of 836 °C. Our future plans for WF measurements are also discussed below.
Non-invasive PSF recovery based on direct illumination from wavelength-dependent speckles
Authors: Wang Zhao , Ma Rui , Liu Jun , He Jing Song , Zhang Wei Li
Published: April 2023

Scattering effect exists widely in practical bioimaging systems, which renders a higher demand for image reconstruction from blurred images. Generally, the point spread function (PSF) of an imaging system works as a powerful key to effectively reconstruct the hidden object even from strongly scattering-induced speckle patterns. However, the direct acquisition of the PSF commonly involves an invasive way like delighting a point in the region of interest, which is typically unavailable in practical applications. Here, we propose a non-invasive PSF recovery method under wavelength-dependent speckle illumination. The PSF is recovered from the uncorrelated intensity patterns through non-negative matrix factorization, while effective image reconstruction is realized by combining it with the multiplexed speckle pattern. It is surprising that a direct illumination, i.e., the lighting and detection utilize the same wavelength and even possess high spatial coherence, still fulfills the effective information extraction using the intensity-only based incoherent algorithm. This work provides a non-invasive way of PSF recovery and facilitates the PSF associated techniques such as image deblurring and super-resolution imaging.
Additive energy functions have predictable landscape topologies
Authors: Story Brittany , Sadhu Biswajit , Adams Henry , Clark Aurora E.
Published: April 2023

Recent work [Mirth et al., J. Chem. Phys. 154, 114114 (2021)] has demonstrated that sublevelset persistent homology provides a compact representation of the complex features of an energy landscape in 3 N-dimensions. This includes information about all transition paths between local minima (connected by critical points of index ≥1) and allows for differentiation of energy landscapes that may appear similar when considering only the lowest energy pathways (as tracked by other representations, such as disconnectivity graphs, using index 1 critical points). Using the additive nature of the conformational potential energy landscape of n-alkanes, it became apparent that some topological features—such as the number of sublevelset persistence bars—could be proven. This work expands the notion of predictable energy landscape topology to any additive intramolecular energy function on a product space, including the number of sublevelset persistent bars as well as the birth and death times of these topological features. This amounts to a rigorous methodology to predict the relative energies of all topological features of the conformational energy landscape in 3N dimensions (without the need for dimensionality reduction). This approach is demonstrated for branched alkanes of varying complexity and connectivity patterns. More generally, this result explains how the sublevelset persistent homology of an additive energy landscape can be computed from the individual terms comprising that landscape.
Honeycomb-kagome FSL-graphene: A carbon allotrope as an ultra-high capacity anode material for fast-rechargeable sodium-ion battery
Authors: Lv Xiao-Wei , Ye Xiao-Juan , Zheng Xiao-Hong , Jia Ran , Liu Chun-Sheng
Published: April 2023

Sodium-ion batteries (SIBs) are promising candidates for large-scale energy storage due to the abundance and low cost of sodium. However, graphite, the primary anode for commercial lithium-ion batteries, cannot be applied to SIBs. Its two-dimensional (2D) counterpart graphene is also inactive toward Na ions because of the delocalized π-electron network. We propose an idea to tackle this problem by introducing kagome topology into the honeycomb lattice, creating localized electronic states for improving the Na storage performance. Herein, we design a form of 2D carbon allotrope (named FSL-graphene), consisting of a kagome and a honeycomb sublattice. It has excellent stability, which is confirmed by the superior cohesive energy, positive phonon modes, high thermal stability, and strong mechanical stability. FSL-graphene exhibits an ultra-high theoretical Na storage capacity of 3347.1 mA h g−1, superior to most previously reported 2D anode materials. In addition, it possesses low diffusion energy barriers (0.19–0.23 eV), low open-circuit voltages (0.59–0.61 V), and small changes in lattice constants (1.3%). Furthermore, the electrolytes with high dielectric constants (e.g., ethylene carbonate) could improve the adsorption and migration of Na on FSL-graphene. This study provides an insight for designing high-performance carbon anode materials for SIBs by focusing on the topological lattices.
Time-correlated luminescence blinking in InGaN single quantum wells
Authors: Yoshida Shunra , Fujii Yusuke , Alfieri Giovanni , Micheletto Ruggero
Published: April 2023

The blinking phenomenon in InGaN single quantum wells is a phenomenon where localized photoluminescence changes over time. Understanding its physics is important for the manufacture of more efficient light emission diodes. We present a study using two InGaN single quantum well samples, emitting at 460 and 510 nm wavelength, respectively. We confirmed that the luminescence intensity fluctuates in localized blinking regions, and we found that these optical variations are not random but are instead correlated in pairs, with either positive or negative coefficient, to a distant reference blinking point. Measurements were performed to obtain standard deviation and cross-correlation maps. Invoking the quantum confined Stark effect, we realized a simple phenomenological model that shows how charge carriers are exchanged among pairs of adjacent opposite correlation regions. As a result, it is suggested that the phenomenon is caused by fluctuations in the number of these exchanged carriers. Our model gives an explanation for the blinking phenomenon in InGaN single quantum wells, and it is important for a deeper understanding to InGaN-based materials.
Planar Hall effect in the quasi-two-dimensional topological semimetal candidate In0.93TaSe2
Authors: Gao Wenshuai , Han Minglong , Chen Zheng , Zhu Ankang , Han Yuyan , Zhu Mengcheng , Zhu Xiangde , Tian Mingliang
Published: April 2023

Here, we report the systematic study on the planar transport properties of the quasi-two-dimensional (quasi-2D) topological nodal-line semimetal candidate In0.93TaSe2. When rotating magnetic field in the plane, the anisotropic longitudinal resistance and planar Hall resistance are clearly observed and can be well described by the theoretical formulation of the planar Hall effect (PHE). Further analysis demonstrates that the anisotropic orbital resistance rather than the topological-nontrivial chiral anomaly plays a dominant role on the PHE in In0.93TaSe2. Our study provides another platform for understanding the mechanism of PHE, which may also be valuable for future planar Hall sensors based on quasi-2D materials.
Breakdown of dipole Born approximation and the role of Rydberg’s predissociation for the electron-induced ion-pair dissociation to oxygen in the presence of background gases
Authors: Kundu Narayan , Kumar Vikrant , Nandi Dhananjay
Published: April 2023

We study the electron-induced ion-pair dissociation to gas-phase oxygen molecules using a state-of-the-art velocity-map ion-imaging technique. The analysis is entirely based on the conical time-gated wedge-shaped velocity slice images of O−/O2 nascent anionic fragments, and the resulting observations are in favor of Van Brunt et al.’s report [R. J. Van Brunt and L. J. Kieffer, J. Chem. Phys. 60, 3057 (1974)]. A new image reconstruction method, Jacobian over parallel slicing, is introduced to overcome the drawback of ion exaggeration in determining the kinetic energy distribution from the time-gated parallel slicing technique, which offers an alternative approach to the wedge slicing method. Most importantly, the role of the quintet-heavy Rydberg state has been drawn out to the complex ion-pair formalism. The extracted kinetic energy and angular distributions from the wedge slice images reveal a high momentum transfer during the ion-pair dissociation process, which could be the finest rationale to observe the breakdown of dipole Born approximation driven by multipole moment associated with the incident electron beam. Three distinct dissociative momentum bands have been precisely identified for O− dissociation. However, radiationless Rydberg’s predissociation continuum (≥15%) has become an inherent character of electron-induced ion-pair dissociation, which could be dealt with using the beyond Born–Oppenheimer treatment. The incoherent sum of Σ and Π symmetric-associated ion-pair final states has been precisely identified by modeling the angular distribution of O−/O2 for each of the kinetic energy bands. A negligibly small amount of forward–backward asymmetry is observed in the angular distribution of O−/O2, which might be explained by the dissociative state-specific quantum coherence mechanism as reported [Krishnakumar et al., Nat. Phys. 14, 149 (2018); Kumar et al., arXiv:2206.15024 (2022)] by Prabhudesai et al.
Background rates of x-ray transition-edge sensor micro-calorimeters under a frequency domain multiplexing readout for solar axion-like particles’ detection
Authors: Vaccaro D. , Gottardi L. , Akamatsu H. , van der Kuur J. , Nagayoshi K. , Taralli E. , de Wit M. , Ravensberg K. , Gao J. R. , den Herder J. W. A.
Published: April 2023

We report on the x-ray background rate measured with transition-edge sensors (TES) micro-calorimeters under frequency-domain multiplexing (FDM) readout as a possible technology for future experiments aiming at a direct detection of axion-like particles. Future axion helioscopes will make use of large magnets to convert axions into photons in the keV range and x-ray detectors to observe them. To achieve this, a detector array with high spectral performance and extremely low background is necessary. TES are single-photon, non-dispersive, high-resolution micro-calorimeters and represent a possible candidate for this application. We have been developing x-ray TES micro-calorimeters and an FDM readout technology in the framework of the space-borne x-ray astronomical observatories. We show that the current generation of our detectors is already a promising technology for a possible axion search experiment, having measured an x-ray background rate of 2.2(2) × 10−4 cm−2 s−1 keV−1 with a cryogenic demonstrator not optimized for this specific application. We then make a prospect to further improve the background rate down to the required value (<10−7 cm−2 s−1 keV−1) for an axion-search experiment, identifying no fundamental limits to reach such a level.
Complexity reduction in density functional theory: Locality in space and energy
Authors: Dawson William , Kawashima Eisuke , Ratcliff Laura E. , Kamiya Muneaki , Genovese Luigi , Nakajima Takahito
Published: April 2023

We present recent developments of the NTChem program for performing large scale hybrid density functional theory calculations on the supercomputer Fugaku. We combine these developments with our recently proposed complexity reduction framework to assess the impact of basis set and functional choice on its measures of fragment quality and interaction. We further exploit the all electron representation to study system fragmentation in various energy envelopes. Building off this analysis, we propose two algorithms for computing the orbital energies of the Kohn–Sham Hamiltonian. We demonstrate that these algorithms can efficiently be applied to systems composed of thousands of atoms and as an analysis tool that reveals the origin of spectral properties.
Chiral symmetry breaking and entropy production in Dean vortices
Authors: Herreros Isabel , Hochberg David
Published: April 2023

In toroidal pipes, the secondary flow in cross section is a mirror symmetric pair of counter-rotating axially oriented Dean vortices. This mirror symmetry is broken in helical pipes. We investigate in detail the mirror symmetry breaking in these secondary flows in going from toroidal to helical geometries. We quantify the degree of mirror symmetry breaking in helical flows by calculating both an (i) order-parameter − 1 ≤ χ ≤ 1 that measures the net integrated chirality of vortices in section and (ii) the entropy production due to both viscous shear forces and convection for Dean vortices as the Dean number and pitch of the helix are varied. We prove that the entropy production due to convective processes is always greater than that due to viscous shear, for stationary incompressible flows in the absence of body forces. For the same pipe radius and pipe curvature, fluid density, viscosity, and entrance flows, the vortex entropy production in the stationary state is minimized for helical conduits (for a given Dean number) with respect to that of toroidal pipes (zero pitch). The dissipation in the fluid flow due to Dean vortices decreases in going from a toroidal to a helical geometry, while the chiral order parameter tends to χ = ± 1 for finite values of the pitch as the Dean number is decreased.
Ionization potentials and fundamental gaps in atomic systems from the Ensemble-DFT approach
Authors: Lavie Sharon , Goshen Yuli , Kraisler Eli
Published: April 2023

Calculations in Kohn–Sham density functional theory crucially rely on high-quality approximations for the exchange-correlation (xc) functional. Standard local and semi-local approximations fail to predict the ionization potential (IP) and the fundamental gap, departing from the Kohn–Sham orbital energies, due to the deviation of the total energy from piecewise-linearity and the absence of the derivative discontinuity. The ensemble generalization procedure introduced in Phys. Rev. Lett. 110, 126403 (2013) restores, to a large extent, these features in any approximate xc functional and improves its ability to predict the IP and the fundamental gap with negligible additional computational effort. In this work we perform an extensive study of atoms and first ions across the Periodic Table, generalizing the local spin-density and the Perdew–Burke–Ernzerhof approximations. By applying the ensemble generalization to a variety of systems, with s-, p-, and d-character, we assess the accuracy of the method and identify important trends. In particular, we find that the accuracy of our approach heavily depends on the character of the frontier orbitals: when d-orbitals are involved, the performance is far less accurate. Possible sources of error are discussed and ways for further improvement are outlined.
2-Propanol interacting with Co3O4(001): A combined vSFS and AIMD study
Authors: Omranpoor Amir H. , Bera Anupam , Bullert Denise , Linke Matthias , Salamon Soma , Webers Samira , Wende Heiko , Hasselbrink Eckart , Spohr Eckhard , Kenmoe Stéphane
Published: April 2023

The interaction of 2-propanol with Co3O4(001) was studied by vibrational sum frequency spectroscopy and ab initio molecular dynamics simulations of 2-propanol dissolved in a water film to gain an insight, at the molecular level, into the pathways of catalytic oxidation. The experimental study has been performed under near ambient conditions, where the presence of water vapor is unavoidable, resulting in a water film on the sample and, thereby, allowing us to mimic the solution–water interface. Both experiment and theory conclude that 2-propanol adsorbs molecularly. The lack of dissociation is attributed to the adsorption geometry of 2-propanol in which the O–H bond does not point toward the surface. Furthermore, the copresent water not only competitively adsorbs on the surface but also inhibits 2-propanol deprotonation. The calculations reveal that the presence of water deactivates the lattice oxygen, thereby reducing the surface activity. This finding sheds light on the multifaceted role of water at the interface for the electrochemical oxidation of 2-propanol in aqueous solution as recently reported [Falk et al., ChemCatChem 13, 2942–2951 (2021)]. At higher temperatures, 2-propanol remains molecularly adsorbed on Co3O4(001) until it desorbs with increasing surface temperature.
Hydrodynamics of body–body interactions in dense synchronous elongated fish schools
Authors: Kelly John , Menzer Alec
Published: April 2023

Mechanisms for hydrodynamic benefit via fluid interactions in large planar fish schools ( n ≥ 10) are investigated by two-dimensional numerical simulations of carangiform fish swimming. It is observed that the average swimming efficiency of the 10-fish school is increased by 30% over a single swimmer, along with a thrust production improvement of 114%. The performance and flow analyses characterize the associated hydrodynamic interaction mechanisms in large dense schools leading to enhanced performance. First, anterior body suction arises from the proximity of the suction side of the flapping tail to the head of the following fish. Next, the block effect is observed as another fish body blocks the flow behind a fish. Finally, the wall effect enhances the flow of momentum downstream where the body of a neighboring fish acts as a wall for the flapping of a fish tail moving toward it. Because these primary body–body interactions are based on the arrangement of surrounding fish, a classification of the individual fish within the school is presented based on the intra-fish interactions and is reflected in the performance of the individuals. It is shown that the school can be separated as front fish, middle fish, edge fish, and back fish based on the geometric position, performance, and wake characteristics. Finally, groupings and mechanisms observed are proven to be consistent over a range of Reynolds numbers and school arrangements.
Influence of coverage on adsorbate diffusion measurements at electrode surfaces by in situ linear optical diffraction
Authors: Kattwinkel Lasse , Magnussen Olaf M.
Published: April 2023

In situ linear optical diffraction is a new method for studies of surface mass transport in electrochemical environments that is based on the equilibration of coverage gratings in an adlayer on the electrode surface. We, here, discuss the temporal evolution of the diffraction intensity on the basis of experimental data for sulfur adsorbates on Pt(111) electrodes in 0.1M H2SO4 and simulations of the time-dependent diffusion profiles. At low and medium sulfur coverage, the decay of the signal exhibits two time scales, which can be explained by the influence of coverage-dependent diffusion rates on the evolution of gratings with large coverage modulation. At high coverage, a further ultra-slow decay process or even a complete termination of the decay is observed, which we attribute to the presence of high-density, ordered, adlayer phases with low sulfur mobility. These results provide insight into the approaches required for extracting quantitative surface transport rates from linear optical diffraction measurements.