bluuebunny/crossref_metadata_2025 huggingface dataset:
Integrable spin chains and the Clifford group
Authors: Jones Nick G. , Linden Noah
Published: October 2022

We construct new families of spin chain Hamiltonians that are local, integrable, and translationally invariant. To do so, we make use of the Clifford group that arises in quantum information theory. We consider translation invariant Clifford group transformations that can be described by matrix product operators (MPOs). We classify translation invariant Clifford group transformations that consist of a shift operator and an MPO of bond dimension two—this includes transformations that preserve locality of all Hamiltonians and those that lead to non-local images of particular operators but, nevertheless, preserve locality of certain Hamiltonians. We characterize translation invariant Clifford group transformations that take single-site Pauli operators to local operators on at most five sites—examples of Quantum Cellular Automata—leading to a discrete family of Hamiltonians that are equivalent to the canonical XXZ model under such transformations. For spin chains solvable by the algebraic Bethe ansatz, we explain how conjugating by an MPO affects the underlying integrable structure. This allows us to relate our results to the usual classifications of integrable Hamiltonians. We also treat the case of spin chains solvable by free fermions.
Numerical study of type-I intermittency in an atmospheric-pressure dielectric barrier discharge
Authors: Zhang Jiao , Cheng Wei , Wang Yanhui , Wang Dezhen
Published: October 2022

Atmospheric-pressure dielectric barrier discharge (AP-DBD) as a complex dissipative dynamical system exhibits rich temporal nonlinear and chaotic behavior. The intermittent chaos in AP-DBD, where the abrupt intensive currents break the regular periodic current oscillations during a discharge process, is studied by numerical simulation. By increasing the control parameter of applied voltage amplitude, random intensive currents occur more frequently, reducing the average laminar length (time interval of regular oscillations). It is found that the average laminar length depending on the control parameter follows the scaling law with an exponent of −0.5, implying a type-I intermittent discharge. This study further supplements and strengthens the nonlinear theory in plasma discharge.
Advances in the use of spiders for direct spinning of nanomaterials-reinforced bionic silk
Authors: Greco Gabriele , Valentini Luca , Pugno Nicola M.
Published: October 2022

This paper deals with the possibility of merging spider silk with nanomaterials by directly feeding them to the spiders. Indeed, creating a soft “bionicomposite” with enhanced mechanical and/or other multifunctional properties, e.g., electric, magnetic, etc., is attractive for material science. Pugno and co-workers were the first to expose spiders to carbon-based nanomaterials, reporting promising results in terms of silk maximal reinforcements. In a subsequent paper, Kelly and co-workers used a different approach and did not obtain any significant strengthening in the silk. These different results highlight the importance of exploring the issue better. In this work, spiders were exposed to nanomaterial solutions with different protocols, and the properties of their silk were monitored for 14 days, displaying a strong protocol influence and inherent day-to-day variability (up to 300% of a single property). This made this paper’s results aligned with both the previous mentioned works, pinpointing the key challenge to merging silk and nanomaterials using spiders. This work should stimulate further studies and discussion on the topic.
Verification of neoclassical toroidal viscosity induced by energetic particles
Authors: Wang Z. R. , Liu Y. Q. , Logan N. C. , Chrystal C. , Munaretto S. , Hu Q. M. , Liu T. , Park J.-K.
Published: October 2022

The thermal particles contributed neoclassical toroidal viscosity (NTV) have been successfully developed and explored by many impressive works such as the study by Shaing et al. [Phys. Plasmas 10, 1443 (2003)] and Zhu et al. [Phys. Rev. Lett. 96, 225002 (2006)]. In this work, the scope of the NTV study is extended to explore the contribution of energetic particles (EPs) through both theory and experiments. In theory, the existence of the NTV torque due to the precessional drift resonance of trapped EPs is identified based on the equivalence between the NTV torque and the perturbed drift kinetic energy [J. Park, Phys. Plasmas 18, 110702 (2011)]. Toroidal modeling with the Magneto Resistive Spectrum - drift Kinetic code [Y. Liu, Phys. Plasmas 15, 112503 (2008)], based on this equivalence, indicates that trapped EPs can contribute a significant amount of the NTV torque. Meanwhile, this work also focuses on developing the dedicated DIII-D experiments in the presence of the n = 2 external magnetic perturbation to verify the EP induced NTV (EP-NTV) by measuring the change of the NTV torque while varying the angle and the voltage of the neutral beam injection. However, the developed experiments have been unable to create conditions necessary to clearly demonstrate the presence of EP-NTV. The main challenge is separating the resonant and non-resonant momentum transport responses in the plasma. The experience, gained from this study, can help the further exploration of EP-NTV in the future experiments.
Recent advances in microresonators and supporting instrumentation for electron paramagnetic resonance spectroscopy
Authors: Abhyankar Nandita , Agrawal Amit , Campbell Jason , Maly Thorsten , Shrestha Pragya , Szalai Veronika
Published: October 2022

Electron paramagnetic resonance (EPR) spectroscopy characterizes the magnetic properties of paramagnetic materials at the atomic and molecular levels. Resonators are an enabling technology of EPR spectroscopy. Microresonators, which are miniaturized versions of resonators, have advanced inductive-detection EPR spectroscopy of mass-limited samples. Here, we provide our perspective of the benefits and challenges associated with microresonator use for EPR spectroscopy. To begin, we classify the application space for microresonators and present the conceptual foundation for analysis of resonator sensitivity. We summarize previous work and provide insight into the design and fabrication of microresonators as well as detail the requirements and challenges that arise in incorporating microresonators into EPR spectrometer systems. Finally, we provide our perspective on current challenges and prospective fruitful directions.
High-P–T impedance measurements using a laser-heated diamond anvil cell
Authors: Okuda Yoshiyuki , Oka Kenta , Kubota Yusuke , Inada Mako , Kurita Naoki , Ohta Kenji , Hirose Kei
Published: October 2022

The electrical conductivity (EC) of minerals found on Earth and throughout the solar system is a fundamental transport property that is used to understand various dynamical phenomena in planetary interiors. High-pressure and high-temperature (P–T) EC measurements are also an important tool for observing phase transitions. Impedance measurements can accurately measure the EC of a nonmetallic sample. In previous measurements under static conditions using a laser-heated diamond-anvil cell (LHDAC), only direct current resistance is measured, but this method overestimates the bulk sample resistance. Moreover, the previous methodology could only be applied to nontransparent samples in an LHDAC using infrared lasers, limiting the range of measurable composition. To the best of our knowledge, no in situ high-P–T EC measurements of transparent materials have been reported using LHDAC techniques. We developed a novel impedance measurement technique under high-P–T conditions in an LHDAC that applies to transparent samples. As a validation, we measured the EC of Mg0.9Fe0.1SiO3 bridgmanite up to 51 GPa and 2000 K and found that the results are consistent with those of previous studies. We also measured the EC values of sodium chloride to compare with those of previous studies, as well as those of cubic boron nitride and zirconia cement to quantify how well they insulate under high P–T conditions. This is the first report of the impedance and EC measurements of transparent minerals in an LHDAC, which allows the measurement of Fe-poor/-free materials, including the major constituents of the interiors of gas giants and icy planets, under extreme conditions.
Sub-threshold ultrafast one-photon photoemission from a Cu(111) photocathode
Authors: Angeloni L. A. , Shan I.-J. , Schroeder W. Andreas
Published: October 2022

Single-photon photoemission of electrons for incident photon energies below the surface work function is reported for a single-crystal Cu(111) photocathode. Spectral characterization of the quantum efficiency and mean transverse energy of the emitted electrons is shown to be consistent with emission from a thermalized hot electron distribution photoexcited on sub-picosecond time scales into an upper conduction band at the L-point of the Brillouin zone of copper. To our knowledge, this is the first time that such excited-state thermionic emission has been observed from a planar metal photocathode, and then from a commonly used photocathode material. The results, therefore, indicate the potential importance of such band structure dependent sub-threshold photoemission mechanisms on the performance of photocathodes employed for the generation of short electron pulses using sub-picosecond laser pulses. Consequently, the combined experimental and theoretical work presented in this paper contributes to solid-state photocathode-based research aimed at our understanding and selection (or discovery) of high brightness photo-electron sources required for many electron-based diffraction, imaging, and accelerator applications.
High-throughput high-dynamic range imaging by spatiotemporally structured illumination
Authors: Woo Taeseong , Kim Hye Yun , Kim Su Yeon , Hwang Byungjae , Ahn Cheolwoo , Kwon Seok-Kyu , Kim Jae-Ick , Park Jung-Hoon
Published: October 2022

Recent advances in biochemistry and optics have enabled observation of the faintest signals from even single molecules. However, although biological samples can have varying degrees of fluorescence expression ranging from a single to thousands of fluorescent molecules in an observation volume, the detection range is fundamentally limited by the dynamic range (DR) of current detectors. In other words, for many biological systems where faint and strong signal sources coexist, traditional imaging methods make a compromise and end up choosing a limited target signal range to be quantitatively measured while other signal levels are either lost beneath the background noise or saturated. The DR can be extended by taking multiple images with varying exposures, which, however, severely restricts data throughput. To overcome this limitation, we introduce structured illumination high dynamic range (SI-HDR) imaging, which enables real-time HDR imaging with a single measurement. We demonstrate the wide and easy applicability of the method by realizing various applications, such as high throughput gigapixel imaging of mouse brain slices, quantitative analysis of neuronal mitochondria structures, and fast 3D volumetric HDR imaging.
Evaluation of a new DIII-D Doppler backscattering system for higher wavenumber measurement and signal enhancement
Authors: Damba J. , Pratt Q. , Hall-Chen V. H. , Hong R. , Lantsov R. , Ellis R. , Rhodes T. L.
Published: October 2022

The high density fluctuation poloidal wavenumber, kθ (kθ > 8 cm−1, kθρs > 5, ρs is the ion gyro radius using the ion sound velocity), measurement capability of a new Doppler backscattering (DBS) system at the DIII-D tokamak has been experimentally evaluated. In DBS, wavenumber (k) matching becomes more important at higher wavenumbers, owing to the exponential dependence of the measured signal loss factor on wave vector mismatch. Wave vector matching allows for the Bragg scattering condition to be satisfied, which minimizes the signal loss at higher k’s. In the previous DBS system, without toroidal wave vector matching, the measured DBS signal-to-noise ratio at higher kθ (>8 cm−1) is substantially reduced, making it difficult to measure higher kθ turbulence. The new DBS system has been optimized to access higher wavenumber, kθ ≤ 20 cm−1, density turbulence measurement. The optimization hardware addresses fluctuation wave vector matching using toroidal steering of the launch mirror to produce a backscattered signal with improved intensity. The probe’s sensitivity to high-k density fluctuations has been increased by approximately an order of magnitude compared to the old system that has been in use at DIII-D. Note that typical measurement locations are above or below the tokamak midplane on the low field side with normalized radial ranges of 0.5–1.0. The new DBS probe system with the toroidal matching of fluctuation wave vectors is thought to be critical to understanding high-k turbulent transport in fusion-relevant research at DIII-D.
Identifying causality drivers and deriving governing equations of nonlinear complex systems
Authors: Ma Haochun , Haluszczynski Alexander , Prosperino Davide , Räth Christoph
Published: October 2022

Identifying and describing the dynamics of complex systems is a central challenge in various areas of science, such as physics, finance, or climatology. While machine learning algorithms are increasingly overtaking traditional approaches, their inner workings and, thus, the drivers of causality remain elusive. In this paper, we analyze the causal structure of chaotic systems using Fourier transform surrogates and three different inference techniques: While we confirm that Granger causality is exclusively able to detect linear causality, transfer entropy and convergent cross-mapping indicate that causality is determined to a significant extent by nonlinear properties. For the Lorenz and Halvorsen systems, we find that their contribution is independent of the strength of the nonlinear coupling. Furthermore, we show that a simple rationale and calibration algorithm are sufficient to extract the governing equations directly from the causal structure of the data. Finally, we illustrate the applicability of the framework to real-world dynamical systems using financial data before and after the COVID-19 outbreak. It turns out that the pandemic triggered a fundamental rupture in the world economy, which is reflected in the causal structure and the resulting equations.
Pre-curing time effect on reactive powder concrete impact resistance
Authors: Wang Xiaohui , Zhao Qingxin , Zhang Shuang , Lu Nan
Published: October 2022

To test the effect of pre-curing time on the impact resistance of reactive powder concrete (RPC), RPC specimens were cured in a steam curing box at a temperature of 70 °C for 72 h with pre-curing times of 18, 24, and 30 h. At 28 days, the low-speed impact test was carried out on RPC specimens with a Ceast9350 drop weight impact system at an impact rate of 5 m/s and impact energy of 140 J. The variation curves of the impact force and displacement of RPC specimens with impact times were obtained. The results show that the impact resistance of RPC specimens improved with the increased pre-curing time, implying that appropriate pre-curing time (30 h in this case) can improve RPC mechanical properties. At the same time, combined with x-ray diffraction, scanning electron microscope imaging of hydration products, and the energy dispersion spectroscopy test, the influence mechanism of pre-curing time on the impact resistance of RPC is analyzed from the microstructure standpoint. The results show that appropriate pre-curing time can make the hydration of cement form finer particles and make the hardened paste form a protective structure to reduce the damage of steam curing in the strength development process. Through multiscale homogenization calculation via the Mori–Tanaka scheme, it can be seen that RPC’s stiffness increases with the prolonged pre-curing time. Optimizing pre-curing time is conducive to improving the mechanical properties of RPC specimens.
Quantitative methods to determine the student workload: II. Statistical models for the microcurricular performance indicators
Authors: Atenas B. , Velazquez L. , Castro-Palacio J. C.
Published: October 2022

Previously, we observed that the student workload follows an inverse relation with the learning rate (an application of the kinematic notion of speed contextualized to the learning process). Motivated by this finding, we propose a quantitative estimation of the learning rate using a different source of information: the historical records of final grades of a given course. According to empirical data analyzed in other similar studies, the distribution functions of final grades exhibit a regular pattern: a Gaussian behavior for the approval region and a homogeneous distribution for the failed one. This fact is combined with the incidence of student elimination–desertion rules for introducing two simple agent-based models. Our analysis is complemented by revisiting the performance indicators typically employed to characterize the student promotion and progression. We discuss some other performance indicators to characterize the learning advancement of students: the group learning rate and the learning curve. We compare the results of Monte Carlo simulations with empirical data, observing a good agreement in the behavior of performance indicators derived from these sources. This analysis suggests an adaptive method for the readjustment of the student workload (the number of academic credits) considering the group learning rates during a follow-up period, which resembles the readjustment of prices of goods (and services) in correspondence with the evolution of supply and demand.
Computation of AC loss of HTS coils wound by coated conductors with different widths
Authors: Yu Liuyuan , Yong Huadong
Published: October 2022

The second-generation high-temperature superconductor (HTS) tape is a promising material for the HTS application. However, the extremely large aspect ratio of the HTS coated tape leads to high power dissipation in the environment of a time-varying magnetic field. Reducing the width of HTS coated tape is a feasible way to decrease the alternating current (AC) loss of devices composed of HTS tapes. In this study, a numerical model of the HTS coil group composed of six sub-coils based on the T-A formulation is presented in which each HTS sub-coil is wound with original or narrow width Y-Ba-Cu-O (YBCO) tape. The 1/3 and 1/4 narrow width tapes are used to represent the tapes, which are divided into three and four equal parts, respectively. Then, we calculate the AC losses in 1/3 and 1/4 narrow width HTS coil groups in different cases. The estimated results of AC loss are compared with those of the HTS coil group wound by HTS tapes with original width. The numerical results show that AC transport losses of 1/3 and 1/4 narrow width HTS coil groups are smaller than that of the original HTS coil group for the applied high current. Furthermore, with the decrease in tape width, the reduction of AC loss becomes more significant. In contrast with the original width HTS coil group, the magnetization losses of the 1/3 and 1/4 narrow width HTS coil groups will decrease at the high magnetic field. In addition, the influences of harmonic components on AC loss are also considered.
Anisotropic Lagrangian dispersion in zonostrophic turbulence in a closed basin
Authors: Durán Colmenares A. H. , Zavala Sansón L.
Published: October 2022

This article studies the anisotropic particle dispersion in a continuously forced, two-dimensional turbulent flow on a β-plane. The flow is immersed in a large-scale closed basin with free-slip walls. The anisotropy is analyzed in two sets of numerical experiments characterized by the magnitude of the imposed, time-dependent forcing (weak and strong). Both experiments exhibit typical features of zonostrophic turbulence: eddy motions that, on average, form alternating east–west circulation bands due to the β-effect. The dispersion anisotropy is investigated through three Lagrangian statistics calculated by zonal and meridional components: (i) relative dispersion between pairs of particles; (ii) dispersion ellipses; and (iii) finite-scale Lyapunov exponents (FSLE), also measured with particle pairs. In the experiment with weak forcing, the relative dispersion and dispersion ellipses show anisotropy with a zonal preference toward the west; however, the FSLE did not reveal significant anisotropy. In the experiment with strong forcing, the relative dispersion and dispersion ellipses show zonal anisotropy toward the west when the particles are far from the boundaries. As the particles reach the western wall and are redistributed to fill the domain, the anisotropy ceases. The FSLE show zonal anisotropy for a wide range of particle separations. The results are examined further by using no-slip boundary conditions and a rectangular domain geometry.
Free time evolution of the quantum wave function and optimal transportation
Authors: Morato Laura M.
Published: October 2022

It is shown that, in the absence of nodes and under regularity assumptions, a solution in a finite interval of time of the free Schrodinger equation solves a minimization problem, which is a stochastic generalization of the classical optimal transportation problem with quadratic cost.
A sample-position-autocorrection system with precision better than 1 µm in angle-resolved photoemission experiments
Authors: Duan Shaofeng , Wang Shichong , Yang Yuanyuan , Huang Chaozhi , Gu Lingxiao , Liu Haoran , Zhang Wentao
Published: October 2022

We present the development of a high-precision sample-position-autocorrection system for photoemission experiments. A binocular vision method based on image pattern matching calculations was realized to track the sample position with an accuracy better than 1 µm, which was much smaller than the spot size of the incident laser. We illustrate the performance of the sample-position-autocorrection system with representative photoemission data on the topological insulator Bi2Se3 and an optimally doped cuprate superconductor Bi2Sr2CaCu2O8+δ. Our method provides new possibilities for studying the temperature-dependent electronic structures in quantum materials using laser-based or spatially resolved photoemission systems with high precision and efficiency.
Superfluid helium nanoscope insert with millimeter working range
Authors: Kamiya Naoki , Kuramoto Kazuki , Takishima Kento , Yumoto Tatsuya , Oda Haruka , Shimi Takeshi , Kimura Hiroshi , Matsushita Michio , Fujiyoshi Satoru
Published: October 2022

A superfluid helium insert was developed for cryogenic microscopy of millimeter-sized specimens. An optical-interferometric position sensor, cryogenic objective mirror, and piezo-driven cryogenic stage were fixed to an insert holder that was immersed in superfluid helium. The single-component design stabilized the three-dimensional position of the sample, with root-mean-square deviations of (x, lateral) 0.33 nm, (y, lateral) 0.29 nm, and (z, axial) 0.25 nm. Because of the millimeter working range of the optical sensor, the working range of the sample under the active stabilization was (x, y) 5 mm and (z) 3 mm in superfluid helium at 1.8 K. The insert was used to obtain the millimeter-sized fluorescence image of cell nuclei at 1.8 K without a sample exchange.
High performance LaNiO3-buffered, (001)-oriented PZT piezoelectric films integrated on (111) Si
Authors: Wang Yingying , Ouyang Jun , Cheng Hongbo , Shi Yushu , Nishikado Takumi , Kanno Isaku
Published: October 2022

Integration of high-performance lead zirconate titanate (PZT) piezoelectric films onto (111) Si substrates is beneficial for the development of piezoelectric micro-electro-mechanical systems (Piezo-MEMS) because of (111) Si's isotropic mechanical properties and desirable etching characteristics. These features will greatly reduce complications in micro-device fabrication and patterning of PZT/Si heterostructures. However, piezoelectric performance of a PZT film is usually dominated by its preferred crystalline orientation, with (001) being superior than (110) and (111). Such a vectorial dependence seriously restricts applications of PZT films grown on (111) Si, which are usually not (001)-textured. In this work, highly (001)-oriented PZT thick films (∼1.5 μm) with a 53/47 Zr/Ti ratio were prepared on (111) Si substrates via a multi-layer buffering technique, i.e., through the use of a (111)Pt/Ti bi-layer and a LaNiO3 buffer layer. The PZT films were sputter-deposited at a low temperature (350 °C) and then crystallized in a (001) texture via a rapid thermal annealing (RTA). The e31,f transverse piezoelectric coefficient was up to ∼11.6 C/m2 for PZT films with a RTA time of 2 minutes. Such an e31,f value is comparable to that of PZT films grown on (100) Si. This work opens up many possibilities for Piezo-MEMS by demonstrating the desirable combination of a large piezoelectricity in (001) PZT with a good patternability of (111) Si.
Exciton optics, dynamics, and transport in atomically thin semiconductors
Authors: Perea-Causin Raul , Erkensten Daniel , Fitzgerald Jamie M. , Thompson Joshua J. P. , Rosati Roberto , Brem Samuel , Malic Ermin
Published: October 2022

Atomically thin semiconductors such as transition metal dichalcogenide (TMD) monolayers exhibit a very strong Coulomb interaction, giving rise to a rich exciton landscape. This makes these materials highly attractive for efficient and tunable optoelectronic devices. In this Research Update, we review the recent progress in the understanding of exciton optics, dynamics, and transport, which crucially govern the operation of TMD-based devices. We highlight the impact of hexagonal boron nitride-encapsulation, which reveals a plethora of many-particle states in optical spectra, and we outline the most novel breakthroughs in the field of exciton-polaritonics. Moreover, we underline the direct observation of exciton formation and thermalization in TMD monolayers and heterostructures in recent time-resolved, angle-resolved photoemission spectroscopy studies. We also show the impact of exciton density, strain, and dielectric environment on exciton diffusion and funneling. Finally, we put forward relevant research directions in the field of atomically thin semiconductors for the near future.
Design and experimental performance of a novel piezoelectric inchworm actuator based on screw clamping principle
Authors: Sun Haichao , Shi Yunlai , Li Xing , Wang Qiang , Lin Yuyang
Published: October 2022

The requirements of large thrust in bidirectional motion, high specific power (power/weight ratio), reliable self-locking at power off state, and compact size envelope for various applications of existing piezoelectric actuators are still urgent. To address these challenges, this study makes full use of the piezoelectric material’s excellent dynamic performance, robust force output, and high energy density to propose a novel inchworm piezoelectric actuator, which relies on the alternate clamping of two nuts independently rotated by two ultrasonic motors on a feed-screw in accordance with a piezoelectric stack (piezo-stack) excitation to accumulate the piezo-stack’s electric field-induced strain periodically and realize power output. The operation principle and design process of the presented actuator were elaborated, and a prototype was fabricated and experimented. Results indicate that the actuator has achieved an expected bidirectional motion for powering the tensile load and compressive load, attained a micrometer-sized step resolution, produced a 3.08 mm/s free speed, a 700 N stall load, and a 1.34 W/kg specific power, and shown a favorable prospect for further development.
Phase transition and twinning in polycrystals probed by in situ high temperature 3D reciprocal space mapping
Authors: Purushottam Raj Purohit Ravi Raj Purohit , Fowan Daniel Pepin , Thune Elsa , Arnaud Stephan , Chahine Gilbert , Blanc Nils , Castelnau Olivier , Guinebretière René
Published: October 2022

Polycrystalline materials exhibit physical properties that are driven by both the interatomic crystallographic structure as well as the nature and density of structural defects. Crystallographic evolutions driven by phase transitions and associated twinning process can be observed in situ in three-dimensional (3D) using monochromatic synchrotron radiation at very high temperatures (over 1000 °C). This paper focuses on continuous measurements of the 3D-reciprocal space maps by high-resolution x-ray diffraction as a function of temperature along a phase transition process occurring between 1200 °C and room temperature. These high precision measurements allow observing the reciprocal space node splitting and the evolution of the diffuse scattering signal around that node as a function of temperature. The capability of this experimental method is illustrated by direct in situ high temperature measurements of the 3D splitting of a reciprocal space node due to phase transition recorded on dense pure zirconia polycrystals.
Thermal response of main protease of SARS and COVID-19 via a coarse-grained approach
Authors: Boonamnaj Panisak , Sompornpisut Pornthep , Pandey R. B.
Published: October 2022

Large-scale Monte Carlo simulations are performed to investigate local and global thermodynamic properties of the main protease in SARS (MP1) and COVID-19 (MP2) coronaviruses using a bond-fluctuating coarse-grained protein model for a range of temperatures. Each of the proteins MP1 and MP2 consists of 306 residues with only 12 specific sites differentiating the two. Thermal responses of the radius of gyration of MP1 and MP2 are very similar. On raising the temperature, the radius of gyration of both MP1 and MP2 exhibits a slow decay in the sub-native regime and reaches a minimum at a characteristic temperature beyond which it increases continuously before saturating at high temperatures to random-coil conformations. The variation of the root mean square displacement of the center of mass of MP1 and MP2 with the time step is also similar to a function of temperature, except that MP2 slows down more than MP1 at low temperatures. Average contact profiles (and complementary mobility profiles) of MP1 and MP2 show their unique segmental globularity, which reduces on raising the temperature, in general, with a distinct trend around few residues. For example, a considerable high degree of contacts is found around residue K180 of MP1 than around residue N180 of MP2, in contrast to higher contacts around residue L286 of MP2 than around I286 of MP1. The changes in contacts of residues V86 and K88 in MP2 with respect to those of residues L86 and R88 in MP1 are also appreciable, but not as large. Distinctions in segmental structures triggered by unique contacts of MP1 and MP2 may be a factor in distinguishing the viral effects of SARS and COVID-19.
Finding influential edges in multilayer networks: Perspective from multilayer diffusion model
Authors: Lin Wei , Xu Li , Fang He
Published: October 2022

With the popularization of social network analysis, information diffusion models have a wide range of applications, such as viral marketing, publishing predictions, and social recommendations. The emergence of multiplex social networks has greatly enriched our daily life; meanwhile, identifying influential edges remains a significant challenge. The key problem lies that the edges of the same nodes are heterogeneous at different layers of the network. To solve this problem, we first develop a general information diffusion model based on the adjacency tensor for the multiplex network and show that the [Formula: see text]-mode singular value can control the level of information diffusion. Then, to explain the suppression of information diffusion through edge deletion, efficient edge eigenvector centrality is proposed to identify the influence of heterogeneous edges. The numerical results from synthetic networks and real-world multiplex networks show that the proposed strategy outperforms some existing edge centrality measures. We devise an experimental strategy to demonstrate that influential heterogeneous edges can be successfully identified by considering the network layer centrality, and the deletion of top edges can significantly reduce the diffusion range of information across multiplex networks.
Synthesis of antiferromagnetic Weyl semimetal Mn3Ge on insulating substrates by electron beam assisted molecular beam epitaxy
Authors: Hong Deshun , Liu Changjiang , Wen Jianguo , Du Qianheng , Fisher Brandon , Jiang J. S. , Pearson John E. , Bhattacharya Anand
Published: October 2022

The antiferromagnetic kagome semimetals Mn3X (X = Ge, Sn, Ga) are of great interest due to properties arising from their Berry curvature, such as large anomalous Nernst and anomalous Hall coefficients, and spin to charge conversion efficiencies at ambient temperatures. However, the synthesis of epitaxial thin films of Mn3Ge in the desired hexagonal phase has been challenging because they do not wet insulating substrates, necessitating the use of a metallic buffer layer. Furthermore, a ferrimagnetic tetragonal phase also forms readily under typical growth conditions, interfering with hexagonal phase properties. We have synthesized atomically smooth and continuous epitaxial thin films of hexagonal Mn3Ge directly on insulating LaAlO3 (111) substrates using electron beam assisted molecular beam epitaxy, using a three-step process that mitigates the formation of the tetragonal phase. The anomalous Nernst coefficient is found to be more than six times larger in our films than in sputtered thin films of Mn3Ge and significantly larger than that of Fe. Our approach can be used to grow thin layers of kagome materials, without interference from a buffer layer in transport properties, and may be applicable to a broader range of materials with large surface energies that do not grow readily on insulating substrates.
Investigation of effective bonding between varied binders and Si anode with different particle sizes
Authors: Lai Yizhu , Li Haodong , Zhang Yanyan , Yang Qing , Li Haoyu , Sun Yan , Liu Yang , Zhong Benhe , Wu Zhenguo , Guo Xiaodong
Published: October 2022

The size of silicon (Si) particles and used binder directly affects the flow uniformity of the slurry, the mechanical properties, and the electrochemical performance of the electrode. In this study, we tried to clarify the adaptation law of Guar gum (GG) and sodium alginate (SA) with 200 nm-Si and 1 μm-Si from the above-mentioned aspects. The rheological properties of the slurry showed that the slurry with GG due to the gelatinization had a poorer dispersion than that with SA. The tests of zeta potentials, thermogravimetric analysis, peeling-off, and nano-indentation profiles explained the performance differences of the electrodes from the mechanical properties. Because of more hydrogen bond sites, the discharge specific capacity of the nm-Si/GG electrode (1116.05 mA h g−1) was higher than the nm-Si/SA electrode (657.74 mA h g−1) after 70 cycles. On the contrary, the μm-Si/SA electrode owing to a rigid skeleton in the SA molecule exhibited a discharge specific capacity of 1681.47 mA h g−1 after 50 cycles, while the μm-Si/GG electrode was 486.58 mA h g−1. In addition, the results inspire more reasonable optimization of the Si-based electrode design.
Period-3 motions to chaos in a periodically forced nonlinear-spring pendulum
Authors: Guo Yu , Luo Albert C. J.
Published: October 2022

In this paper, the complete bifurcation dynamics of period-3 motions to chaos are obtained semi-analytically through the implicit mapping method. Such an implicit mapping method employs discrete implicit maps to construct mapping structures of periodic motions to determine complex periodic motions. Analytical bifurcation trees of period-3 motions to chaos are determined through nonlinear algebraic equations generated through the discrete implicit maps, and the corresponding stability and bifurcations of periodic motions are achieved through eigenvalue analysis. To study the periodic motion complexity, harmonic amplitudes varying with excitation amplitudes are presented. Once more, significant harmonic terms are involved in periodic motions, and such periodic motions will be more complex. To illustrate periodic motion complexity, numerical and analytical solutions of periodic motions are presented for comparison, and the corresponding harmonic amplitudes and phases are also presented for such periodic motions in the bifurcation trees of period-3 motions to chaos. Similarly, other higher-order periodic motions and bifurcation dynamics for the nonlinear spring pendulum can be determined. The methods and analysis presented herein can be applied for other nonlinear dynamical systems.
Polariton enhanced free charge carrier generation in donor–acceptor cavity systems by a second-hybridization mechanism
Authors: Wu Weijun , Sifain Andrew E. , Delpo Courtney A. , Scholes Gregory D.
Published: October 2022

Cavity quantum electrodynamics has been studied as a potential approach to modify free charge carrier generation in donor–acceptor heterojunctions because of the delocalization and controllable energy level properties of hybridized light–matter states known as polaritons. However, in many experimental systems, cavity coupling decreases charge separation. Here, we theoretically study the quantum dynamics of a coherent and dissipative donor–acceptor cavity system, to investigate the dynamical mechanism and further discover the conditions under which polaritons may enhance free charge carrier generation. We use open quantum system methods based on single-pulse pumping to find that polaritons have the potential to connect excitonic states and charge separated states, further enhancing free charge generation on an ultrafast timescale of several hundred femtoseconds. The mechanism involves polaritons with optimal energy levels that allow the exciton to overcome the high Coulomb barrier induced by electron–hole attraction. Moreover, we propose that a second-hybridization between a polariton state and dark states with similar energy enables the formation of the hybrid charge separated states that are optically active. These two mechanisms lead to a maximum of 50% enhancement of free charge carrier generation on a short timescale. However, our simulation reveals that on the longer timescale of picoseconds, internal conversion and cavity loss dominate and suppress free charge carrier generation, reproducing the experimental results. Thus, our work shows that polaritons can affect the charge separation mechanism and promote free charge carrier generation efficiency, but predominantly on a short timescale after photoexcitation.
Study of multilayer flow of a bi-viscous Bingham fluid sandwiched between hybrid nanofluid in a vertical slab with nonlinear Boussinesq approximation
Authors: Basavarajappa Mahanthesh , Myson Shruthy , Vajravelu Kuppalapalle
Published: October 2022

Bi-viscosity Bingham plastic fluids are used to understand the rheological characteristics of pigment–oil suspensions, polymeric gels, emulsions, heavy oil, etc. In many industrial and engineering problems involving high-temperature situation, a linear density-temperature variation is inadequate to describe the convective heat transport. Therefore, the characteristics of the nonlinear convective flow of a bi-viscous Bingham fluid (BVBF) through three layers in a vertical slab are studied. The two outer layers of the oil-based hybrid nanofluid and the intermediate layer of BVBF are considered. The thermal buoyancy force is governed by the nonlinear Boussinesq approximation. Continuity of heat flux, velocity, shear stress, and temperature are imposed on the interfaces. The governing equations are derived from the Navier–Stokes equation, conservation of energy, and conservation of mass for three layers. The nonlinear multi-point (four-point) boundary value problem is solved using the differential transform method (DTM). Converging DTM solutions are obtained, and they are validated. The entropy equation and Bejan number were also derived and analyzed. It is established that the nonlinear density–temperature variation leads to a significant improvement in the magnitude of the velocity and temperature profiles due to the increased buoyancy force, and as a result, the drag force on the walls gets reduced. The drag force on the slab gets reduced by decreasing the volume fraction of nanoparticles. Furthermore, nonlinear convection and mixed convection give rise to an advanced rate of heat transport on the walls and thereby to an enhanced heat transport situation.
Study of the process of metal droplets with high surface tension impinging on wall
Authors: Li Fengchao , Hu Ying , Han Wenxue , Fu Yu , Li Mengzhe , Li Chao , Hu Chunbo
Published: October 2022

The behavior of aluminum droplets impacting a wall critically affects the operation of solid rocket motors. In the present study, the flow and rebound of aluminum droplets with a high surface tension are studied experimentally and numerically. In addition, the impact of aluminum droplets at different inclined angles is monitored experimentally. When the droplet is about to rebound away from the wall, it is stretched to its maximum length. An empirical correlation formula is proposed to predict the maximum length when a droplet is about to bounce off a flat plane. The velocity and pressure distributions of a droplet flowing over a flat plane and an inclined plane are compared by using the volume of fluid method. Furthermore, the restitution coefficient of the droplet is discussed in detail. When normal Weber number Wen ranges from 0 to 20, normal restitution coefficient en ranges from 0.3 to 0.6. When tangential Weber number Wet <10, tangential restitution coefficient et is subject to great uncertainty. When 10 < Wet < 80, et is maintained at 0.75. The formulas for the total restitution coefficient, normal restitution coefficient, and tangential restitution coefficient of the aluminum droplets are also presented. Based on the principle of conservation of energy, we calculate the remaining energy of the aluminum droplets impinging on a wall and provide the relationship between the restitution coefficient and the dissipated energy. The results elucidate the mechanisms at work when aluminum droplets collide with a wall.
Adsorption structure deteriorating negative electron affinity under the H2O environment
Authors: Kashima M. , Ishiyama S. , Sato D. , Koizumi A. , Iijima H. , Nishitani T. , Honda Y. , Amano H. , Meguro T.
Published: October 2022

Photocathodes with negative electron affinity (NEA) characteristics have various advantages, such as small energy spread, high spin polarization, and ultrashort pulsing. Nitride semiconductors, such as GaN and InGaN, are promising materials for NEA photocathodes because their lifetimes are longer than those of other materials. In order to further prolong the lifetime, it is important to better understand the deterioration of NEA characteristics. The adsorption of residual gases and back-bombardment by ionized residual gases shorten the lifetime. Among the adsorbed residual gases, H2O has a significant influence. However, the adsorption structures produced by the reaction with H2O are not comprehensively studied so far. In this study, we investigated adsorption structures that deteriorated the NEA characteristics by exposing InGaN and GaAs to an H2O environment and discussed the differences in their lifetimes. By comparing the temperature-programmed desorption curves with and without H2O exposure, the generation of CsOH was confirmed. The desorption of CsOH demonstrated different photoemission behaviors between InGaN and GaAs results. InGaN recovered its NEA characteristics, whereas GaAs did not. Considering the Cs desorption spectra, it is difficult for an NEA surface on InGaN to change chemically, whereas that for GaAs changes easily. The chemical reactivity of the NEA surface is different for InGaN and GaAs, which contributes to the duration of photoemission. We have attempted to prolong the lifetime of InGaN by recovering its NEA characteristics. We found that InGaN with NEA characteristics can be reused easily without thermal treatment at high temperatures.
Characterisation of buckwheat (Fagopyrum spp.) diversity of the northwestern Himalayas
Authors: Naik Samiullah , Mahajan Reetika , Sofi Parvaze A. , Abidi Ishfaq , Ali Gowhar , Nehvi F. A. , Khan Imran , Bhat Sajad A. , Bhat M. Ashraf , Bhat Bilal Ahmad , Dar Waseem Ali , Zargar Sajad Majeed
Published: October 2022

Content Knowledge about genetic variability parameters is imperative for improving crop plants for traits of economic importance. This paper reports the characterisation of a large germplasm set of an underutilised pseudocereal Buckwheat endemic to northwestern Himalayas in order to elucidate the nature of variability as well as identify trait specific genotypes for use in buckwheat breeding programmes. Aim The major aim was to estimate the genetic variability of yield and related traits in diverse germplasm lines of buckwheat collected from different regions of the north-western Himalayas. Methods The material was evaluated in a randomised complete block design with five replications at two different locations in SKUAST-K, Shuhama and MAR & ES Izmarg, Gurez, during the years 2020 and 2021. For assessing diversity patterns, the clustering of the germplasm from both locations was done by Tocher’s method. Key results The results indicated significant variability in the buckwheat germplasm for all morphological traits across locations. The phenotypic cofficient of variation and genotypic coefficients of variation (PCV, GCV), broad sense heritability and genetic advance values varied between locations. Pooled across locations, the highest PCV values were recorded for number of primary branches. Heritability ranged from low for number of secondary branches to medium for days to 50% flowering. Conclusion The present study provided valuable insights about the variability and trait diversity in buckwheat germplasm under Northwestern Himalayan conditions. Implications The information on variability parameters can be harnessed to develop an effective breeding strategy for improving buckwheat for traits of economic interest.
A scientometric review of research in Translation Studies in the twenty-first century
Authors: Zhu Xuelian , Aryadoust Vahid
Published: October 2022

The field of Translation Studies has expanded rapidly in the twenty-first century, largely due to the growing demand for translation and interpreting professionals. This study provides a scientometric review of Translation Studies to identify its developmental trends and patterns over the past two decades. Document co-citation analysis was conducted on 6007 journal articles published in the fifteen translation studies journals indexed in the Web of Science between January 2001 and December 2020. Twelve document co-citation analysis networks were generated and compared. Quantitative analyses, including temporal and structural metrics, confirmed the robustness and reliability of a network comprising ten discrete research clusters. A timeline view was generated to visualize how these clusters have evolved over time. Ten clusters were identified as major research subdomains in Translation Studies, namely translation competence, translation in conflict zones, translator training, collaborative translation, translation and society, language policy, post-editing and revision, media translation, the translation profession, and web localization. In addition, burst detection analysis identified the twenty most influential publications in this sample. Based on these findings, we discuss how the observed trends in each cluster contribute to further developments in Translation Studies. The implications for teaching, research, and theory are discussed and some methodological guidelines are proposed for future research.