bluuebunny/crossref_metadata_2025 huggingface dataset:
Undisciplining the university through shared purpose, practice, and place
Authors: Freiband Andrew , Dickin Katherine L. , Glass Mitchell , Gore Michael A. , Hinestroza Juan , Nelson Rebecca , Platt Verity , Rooks Noliwe , Sachs Aaron , Stern Nathaniel , Lehmann Johannes
Published: May 2022

Interdisciplinary scholarship and education remains elusive at modern universities, despite efforts at both the individual and institutional levels. The objective of this paper is to identify the main motivations that bring different disciplines together in joint research and identify some of the obstacles to that coming together. Here we propose that shared purpose (why do I participate?), practice (how do we interact?), and place (where do we interact?) are, in descending order, the most important drivers for what we call “undisciplinary” research in an interaction of different disciplines. Through unstructured workshops we found the choice of participants (who participates?), aspects of time (when do we interact?), and especially the research topics and focus (what are we working on?), to be less important for individual faculty engagement. Metaphor analysis obtained during a charrette-style workshop with 13 faculty from multiple disciplines suggested “inter-epistemological ways of knowing” rather than fields of study to move us from disciplinary to interdisciplinary to undisciplinary scholarship and education. Specifically, the broad intent (why do we participate?) was found to increase the impact of undisciplinary approaches that served as drivers for engagement. These lessons learned from a series of workshops were put to the test at an experimental center that clarified the importance of both synchronous and asynchronous interactions in a common space large enough to allow these and located outside the university. Despite the valuable insights gained in what undisciplinary interaction may look like in a center, it remained clear that space design must start by mapping out why and how individuals in different disciplines may want to interact at a given institution to generate buy-in and build the foundation for continuous refinement of an institutional strategy.
Climate Change and Management of Aging Earthen Levees and Embankments
Authors:   American Society of Civil Engineers
Published: May 2022

g the effects of climate change must be adopted Past Present Future •Evaluate past cases of embankment infrastructure failures •Identify key stakeholders •Survey existing dams and levees • Develop foolproof prediction models • Strategize mitigation in case of embankment failures A
Effect of density gradients on the generation of a highly energetic and strongly collimated proton beam from a laser-irradiated Gaussian-shaped hydrogen microsphere
Authors: Bhagawati Ankita , Das Nilakshi
Published: May 2022

An investigation is made on the influence of the sharpness of the density gradients on the generation of energetic protons in a radially Gaussian density profile of a spherical hydrogen plasma. It is possible to create such density gradients by impinging a solid density target with a secondary lower intensity pulse, which ionizes the target and explodes it to create an expanded plasma target of lower effective density for the high-intensity main pulse to hit on. The density gradients are scanned in the near-critical regime, and separate regimes of proton motion are identified based on the density sharpness. An intermediate-density gradient [npeak≈(1.5–2.5)γnc] favors the generation of high energetic protons with narrow energy spectra that are emitted with better collimation from the target rear surface. Protons with energies exceeding 100 MeVs could be achieved using such modified plasma targets with circularly polarized lasers of peak intensities I0∼1020 W cm−2 and peak energy ∼10 J.
Computational analysis of copper electrodeposition into a porous preform
Authors: Hossain Bhuiyan Md Emran , Minary-Jolandan Majid
Published: May 2022

Electroplating of metals into a porous preform with conductive walls is relevant in the fabrication of structural composites, fuel cells and batteries, and microelectronics. Electrodeposition process parameters, such as direct current or pulsed current, electric potential, and electrolyte concentration, as well as preform geometry, have important implications in the process outcomes including the filling process and the percentage of the infiltrated volume. Although electroplating into a vertical interconnect access (with nonconductive walls) for microelectronic applications has been extensively studied, the "flow-through" electroplating into a channel geometry with conducive walls has not been previously investigated. Here, copper infiltration into a such channel has been investigated using computational analysis for the first time. The effects of the inlet flow velocity, potential, electrolyte concentration, and microchannel geometry are systematically studied to quantify their influence on the electrodeposition rate, uniformity of the deposition front, and the infiltrated area within the channel. Computational results revealed that the unfilled area can be reduced to lower than 1% with a low applied potential, a high electrolyte concentration, and no inflow velocity. The results can be used to guide experiments involving electroplating metals into porous preforms toward reliable and reproducible manufacturing processes.
Anisotropic electron and lattice dynamics in excitonic insulator Ta2NiSe5
Authors: Chu Lingqiao , Zhang Kai , Yang Jin , Jiang Huachao , Wang Zhenyou , Su Fuhai
Published: May 2022

We employ polarization-resolved femtosecond optical pump–probe spectroscopy to investigate the nonequilibrium photocarrier dynamics in excitonic insulator Ta2NiSe5. The electronic dynamics, including hot carrier cooling, exciton formation, and recombination in the timescale ranging from subpicoseconds to a few tens of picoseconds, have been established from the transient reflectivity spectra, showing strong in-plane anisotropy with respect to the probe polarization. Such anisotropic photocarrier dynamics possibly arise from the crystalline orientation dependence of the excitonic polarizability. Furthermore, we find that the amplitude of coherent phonons with a frequency of 1 THz is subject to the probe polarization, whereas it is not sensitive to the pump polarization. This substantiates that the displacive excitation of coherent phonons plays a decisive role in lattice dynamics. In addition, we find that the photo-induced dielectric screening tends to suppress the amplitude of coherent phonons with increasing pump fluence, manifesting a remarkable polarization dependence. Our work provides valuable insights into the excitonic dynamics and the origin of coherent phonon generation and also may contribute to the development of polarization-sensitive photoelectric devices based on Ta2NiSe5.
Perfectness of the main-chain alignment in the conjugated polymer films prepared by the floating film transfer method
Authors: Syafutra Heriyanto , Toyoda Jumpei , Pandey Manish , Kumari Nikita , Benten Hiroaki , Nakamura Masakazu
Published: May 2022

Polymer semiconductor/gate dielectric interface is well known to influence the charge transport behaviors in organic field-effect transistors (OFETs). In the unidirectional floating-film transfer method (UFTM), thin floating films of uniaxially aligned π-conjugated polymers are solidified at the air/liquid interface before transferring them onto device substrates. Therefore, packing structures in the films prepared by UFTM are not affected by the strong interactions with the device substrate as usually seen in other film growth methods. Here, one question arises: will the difference in interactions between the liquid substrate and air impact the orientational structure of the polymer chain near the two surfaces or not? To answer this question, we have studied the charge-transport anisotropy in top- and bottom-gate OFETs by changing the film thickness. As a result, the field-effect carrier mobility and its anisotropy did not significantly differ for both surfaces and were constant against the film thickness. These results indicate that the UFTM can provide unidirectional alignment of polymer chains throughout the film thickness and gives a similar superior performance either for a bottom- or a top-gate OFET.
Evaluation of molecular photophysical and photochemical properties using linear response time-dependent density functional theory with classical embedding: Successes and challenges
Authors: Liang WanZhen , Pei Zheng , Mao Yuezhi , Shao Yihan
Published: May 2022

Time-dependent density functional theory (TDDFT) based approaches have been developed in recent years to model the excited-state properties and transition processes of the molecules in the gas-phase and in a condensed medium, such as in a solution and protein microenvironment or near semiconductor and metal surfaces. In the latter case, usually, classical embedding models have been adopted to account for the molecular environmental effects, leading to the multi-scale approaches of TDDFT/polarizable continuum model (PCM) and TDDFT/molecular mechanics (MM), where a molecular system of interest is designated as the quantum mechanical region and treated with TDDFT, while the environment is usually described using either a PCM or (non-polarizable or polarizable) MM force fields. In this Perspective, we briefly review these TDDFT-related multi-scale models with a specific emphasis on the implementation of analytical energy derivatives, such as the energy gradient and Hessian, the nonadiabatic coupling, the spin–orbit coupling, and the transition dipole moment as well as their nuclear derivatives for various radiative and radiativeless transition processes among electronic states. Three variations of the TDDFT method, the Tamm–Dancoff approximation to TDDFT, spin–flip DFT, and spin-adiabatic TDDFT, are discussed. Moreover, using a model system (pyridine–Ag20 complex), we emphasize that caution is needed to properly account for system–environment interactions within the TDDFT/MM models. Specifically, one should appropriately damp the electrostatic embedding potential from MM atoms and carefully tune the van der Waals interaction potential between the system and the environment. We also highlight the lack of proper treatment of charge transfer between the quantum mechanics and MM regions as well as the need for accelerated TDDFT modelings and interpretability, which calls for new method developments.
Combined contributions of carotenoids and chlorophylls in two-photon spectra of photosynthetic pigment–protein complexes—A new way to quantify carotenoid dark state to chlorophyll energy transfer?
Authors: Nowak Julia , Füller Janin , Walla Peter Jomo
Published: May 2022

Transitions into the first excited state of carotenoids, Car S1, are optically forbidden in conventional one-photon excitation (OPE) but are possible via two-photon excitation (TPE). This can be used to quantify the amount of Car S1 to Chlorophyll (Chl) energy transfer in pigment–protein complexes and plants by observing the chlorophyll fluorescence intensity after TPE in comparison to the intensity observed after direct chlorophyll OPE. A parameter, ΦCouplingCar S1−Chl, can be derived that directly reflects relative differences or changes in the Car S1 → Chl energy transfer of different pigment–protein complexes and even living plants. However, very careful calibrations are necessary to ensure similar OPE and TPE excitation probabilities and transition energies. In plants, the exact same sample spot must be observed at the same time. All this is experimentally quite demanding. ΦCouplingCar S1−Chl also corrects intrinsically for direct chlorophyll TPE caused by larger chlorophyll excesses in the complexes, but recently it turned out that in certain TPE wavelengths ranges, its contribution can be quite large. Fortunately, this finding opens also the possibility of determining ΦCouplingCar S1−Chl in a much easier way by directly comparing values in TPE spectra observed at wavelengths that are either more dominated by Cars or Chls. This avoids tedious comparisons of OPE and TPE experiments and potentially allows measurement at even only two TPE wavelengths. Here, we explored this new approach to determine ΦCouplingCar S1−Chl directly from single TPE spectra and present first examples using known experimental spectra from Cars, Chl a, Chl b, LHC II, and PS 1.
Difficulty of the evaluation of the barrier height of an open-shell transition state between closed shell minima: The case of small C4n rings
Authors: David Grégoire , Ben Amor Nadia , Zeng Tao , Suaud Nicolas , Trinquier Georges , Malrieu Jean-Paul
Published: May 2022

C4n cyclacenes exhibit strong bond-alternation in their equilibrium geometry. In the two equivalent geometries, the system keeps an essentially closed-shell character. The two energy minima are separated by a transition state suppressing the bond-alternation, where the wave function is strongly diradical. This paper discusses the physical factors involved in this energy difference and possible evaluations of the barrier height. The barrier given as the energy difference between the restricted density functional theory (DFT)/B3LYP for the equilibrium and the broken symmetry DFT/B3LYP of the transition state is either negative or small, in contradiction with the most reliable Wave Function Theory calculations. The minimal (two electrons in two molecular orbitals) Complete Active Space self-consistent field (CASSCF) overestimates the barrier, and the subsequent second-order perturbation cancels it. Due to the collective character of the spin-polarization effect, it is necessary to perform a full π CASSCF + second-order perturbation to reach a reasonable value of the barrier, but this type of treatment cannot be applied to large molecules. DFT procedures treating on an equal foot the closed-shell and open-shell geometries have been explored, such as Mixed-Reference Spin-Flip Time-dependent-DFT and a new spin-decontamination proposal, namely, DFT-dressed configuration interaction, but the results still depend on the density functional. M06-2X without or with spin-decontamination gives the best agreement with the accurate wave function results.
Elucidating the molecular orbital dependence of the total electronic energy in multireference problems
Authors: Boyn Jan-Niklas , Mazziotti David A.
Published: May 2022

The accurate resolution of the chemical properties of strongly correlated systems, such as biradicals, requires the use of electronic structure theories that account for both multi-reference and dynamic correlation effects. A variety of methods exist that aim to resolve the dynamic correlation in multi-reference problems, commonly relying on an exponentially scaling complete-active-space self-consistent-field (CASSCF) calculation to generate reference molecular orbitals (MOs). However, while CASSCF orbitals provide the optimal solution for a selected set of correlated (active) orbitals, their suitability in the quest for the resolution of the total correlation energy has not been thoroughly investigated. Recent research has shown the ability of Kohn–Shan density functional theory to provide improved orbitals for coupled cluster (CC) and Møller–Plesset perturbation theory (MP) calculations. Here, we extend the search for optimal and more cost effective MOs to post-configuration-interaction [post-(CI)] methods, surveying the ability of the MOs obtained with various density functional theory (DFT) functionals, as well as Hartree–Fock and CC and MP calculations to accurately capture the total electronic correlation energy. Applying the anti-Hermitian contracted Schrödinger equation to the dissociation of N2, the calculation of biradical singlet–triplet gaps, and the transition states of bicylobutane isomerization, we demonstrate that DFT provides a cost-effective alternative to CASSCF in providing reference orbitals for post-CI dynamic correlation calculations.
Annealing enhanced ferromagnetic resonance of thickness-dependent FeGa films
Authors: Guo Xinfang , Wang Fangzhou , Ma Xiaoqi , Li Qiuyue , Liu Meihong , Chen Xiaowen , Yu Jing , Xu Jie , Li Shandong , Wang Jianbo , Liu Qingfang , Cao Derang
Published: May 2022

We report the influence of different annealing temperatures on the magnetic property of FeGa thin films. The measurement was done for the film thickness from 42 to 420 nm. Our results show that the annealing temperature affects not only the microstructure but also the ferromagnetic resonance signal of the film. Annealing of a FeGa film improves the in-plane remanence ratio and reduces the in-plane ferromagnetic resonance linewidth by a factor of five. This annealing treatment promotes film texture and releases compressive stresses in the film. Our results demonstrate that the structural control via annealing is viable. The necessary magnetic softness of the FeGa film for microwave applications can be achieved.
Ab initio study of the adsorption properties of CO2 reduction intermediates: The effect of Ni5Ga3 alloy and the Ni5Ga3/ZrO2 interface
Authors: De Sousa Rafael A. , Ocampo-Restrepo Vivianne K. , Verga Lucas G. , Da Silva Juarez L. F.
Published: May 2022

The Ni5Ga3 alloy supported on ZrO2 is a promising catalyst for the reduction of CO2 due to its higher selectivity to methanol at ambient pressure, e.g., activity comparable to industrial catalysts. However, our atomistic understanding of the role of the cooperative effects induced by the Ni5Ga3 alloy formation and its Ni5Ga3/ZrO2 interface in the CO2 reduction is still far from satisfactory. In this work, we tackle these questions by employing density functional theory calculations to investigate the adsorption properties of key CO2 reduction intermediates (CO2, H2, cis-COOH, trans-COOH, HCOO, CO, HCO, and COH) on Ni8, Ga8, Ni5Ga3, (ZrO2)16, and Ni5Ga3/(ZrO2)16. We found that Ni containing clusters tended to assume wetting configurations on the (ZrO2)16 cluster, while the presence of Ga atoms weakens the adsorption energies on the oxide surface. We also observed that CO2 was better activated on the metal–oxide interfaces and on the oxide surface, where it was able to form CO3-like structures. Meanwhile, H2 activation was only observed on Ni sites, which indicates the importance of distinct adsorption sites that can favor different CO2 reduction steps. Moreover, the formation of the metal–oxide interface showed to be beneficial for the adsorption of COOH isomers and unfavorable for the adsorption of HCOO.
An alternative, dynamic density functional-like theory for time-dependent density fluctuations in glass-forming fluids
Authors: Szamel Grzegorz
Published: May 2022

We propose an alternative theory for the relaxation of density fluctuations in glass-forming fluids. We derive an equation of motion for the density correlation function that is local in time and is similar in spirit to the equation of motion for the average non-uniform density profile derived within the dynamic density functional theory. We identify the Franz–Parisi free energy functional as the non-equilibrium free energy for the evolution of the density correlation function. An appearance of a local minimum of this functional leads to a dynamic arrest. Thus, the ergodicity breaking transition predicted by our theory coincides with the dynamic transition of the static approach based on the same non-equilibrium free energy functional.
Contribution of both bulk and surface states on photothermoelectric transport in epitaxial Bi2Se3 thin films
Authors: Ghimire Mohan Kumar , Kim Donguk , Park Yun Daniel
Published: May 2022

Probing the surface states in Bi2Se3 via electronic transport measurements is difficult due to the significantly larger numbers of bulk carriers. Herein, we report the contribution of both bulk and surface states on the measured photocurrent at room temperature and the electrical transport measurements at low temperatures in an epitaxial thin film of intrinsic Bi2Se3 capped with a high K dielectric, Al2O3. The measured photocurrent continuously increases when the gate voltage is swept toward the negative side from 10 to −10 V, indicating the movement of the Fermi level below the conduction band edge. Moreover, the contribution of the surface state conduction increases when the Fermi level moves inside the bandgap toward the Dirac point. Furthermore, the measured Seebeck coefficient (S) continuously increases with sweeping gate voltage from 10 to −10 V. Similar correlations of the photocurrent and S value with the gate voltage illustrate the contribution of the photothermoelectric effect due to the conduction of both bulk and surface states. Additionally, the ambipolar charge transport was observed in the electrical measurement at 32 K for the four-probe configuration. The ambipolar charge transport is possibly indicative of surface state transport.
Ultrafast light-induced THz switching in exchange-biased Fe/Pt spintronic heterostructure
Authors: Kumar Sandeep , Kumar Sunil
Published: May 2022

The ultrafast optical control of magnetization in spintronic structures enables one to access to the high-speed information processing, approaching the realm of terahertz (THz). Femtosecond visible/near-infrared laser-driven ferromagnetic/nonmagnetic metallic spintronic heterostructures-based THz emitters combine the aspects from the ultrafast photo-induced dynamics and spin-charge inter-conversion mechanisms through the generation of THz electromagnetic pulses. In this Letter, we demonstrate photoexcitation density-dependent induced exchange-bias tunability and THz switching in an annealed Fe/Pt thin-film heterostructure, which otherwise is a widely used conventional spintronic THz emitter. By combining the exchange-bias effect along with THz emission, the photo-induced THz switching is observed without any applied magnetic field. These results pave the way for an all-optical ultrafast mechanism to exchange-bias tuning in spintronic devices for high-density storage, read/write magnetic memory applications.
Temporally stable rotational coherent states for molecular simulations. II. Symmetric rotor case
Authors: Stopera Christopher , Morales Jorge A.
Published: May 2022

Following our preceding work on spherical and linear rotors [C. Stopera and J. A. Morales, J. Chem. Phys. 152, 134112 (2020)], we reformulate an earlier rotational coherent state (CS) set to obtain a temporally stable (TS) CS set for symmetric rotors. Being TS, the new CSs remain within its own set during dynamics by evolving exclusively through their parameters. The TS CS set is now appropriate to reconstruct quantum rotational properties from classical-mechanics simulations of chemical reactions. Following literature precedents, we enforce temporal stability by incorporating action-angle-related phase factors into two parameters of the original CS set. Proofs and final expressions of the symmetric-rotor CS turn out more intricate than those of its spherical-rotor counterpart. We demonstrate and examine the key properties of the new CS set: continuity, resolution of unity, temporal stability, action identity, minimum uncertainty relationships, and quasi-classical behavior. Regarding the last property, we demonstrate that the body-fixed z-component of the CS angular momentum average evolves exactly as its classical counterpart, and that the x- and y-components display an astonishing analogy with their classical counterparts in terms of functional form, precession angular velocities, amplitudes, and phases. We elucidate some of these properties via computer simulations of a rotating benzene molecule represented with the CS set. We discuss the utilization of this CS set to reconstruct quantum rotational properties of symmetric-rotor molecules from classical-mechanics simulations. The new CS set is appropriate to establish quantum-classical connections for rotational properties in chemical dynamics, statistical mechanics, spectroscopy, nuclear physics, and quantum computing.
Large negative thermal expansion induced by cation dimerization in ilmenite-type vanadate ceramic
Authors: Yamamoto Hajime , Kamiyama Sachiko , Nishikubo Takumi , Azuma Masaki , Yamada Ikuya , Kimura Hiroyuki
Published: May 2022

A significant negative thermal expansion (NTE) in an ilmenite-type MgVO3 ceramic is reported in this paper. MgVO3 undergoes V–V dimerization at 500–550 K accompanied by a structural phase transition from the triclinic (low-temperature) to rhombohedral (high-temperature) phase. This transition induces a large anisotropic crystal structure deformation and results in a large NTE in the ceramic sample, which is caused by the microstructural effect. The NTE was observed over a temperature range of 450–630 K, and the total volume shrinkage reached approximately −0.7%. This study demonstrates that controlling the chemical bonding is a promising method for the creation of NTE materials.
Vertically stacked multilayer atomic-layer-deposited sub-1-nm In2O3 field-effect transistors with back-end-of-line compatibility
Authors: Zhang Zhuocheng , Lin Zehao , Si Mengwei , Zhang Di , Dou Hongyi , Chen Zhizhong , Charnas Adam , Wang Haiyan , Ye Peide D.
Published: May 2022

In this work, we demonstrate vertically stacked multilayer sub-1-nm In2O3 field-effect transistors (FETs) with surrounding gate in a back-end-of-line (BEOL) compatible low-temperature fabrication process. A typical bottom-gated single layer In2O3 FET with maximum on-state current (ION) of 890 μA/μm at VDS = 0.8 V and an on/off ratio over 106 is achieved with a channel length (Lch) of 100 nm. The effects of HfO2 capping and O2 annealing are systematically studied, which is critical to realizing the multilayer FETs. Each atomically thin In2O3 channel layer with a thickness (TIO) of 0.9 nm is realized by atomic layer deposition (ALD) at 225 °C. Multilayer FETs with a number of In2O3 layers up to 4 and 1.2 nm-thick HfO2 between each individual layer are fabricated. An enhancement of on-state current (ION) from 183 μA in a single layer In2O3 FET to 339 μA in a 4 layer device with an on/off ratio of 3.4 × 104 is achieved, demonstrating the key advantage of the multilayer FETs to improve the current. Several critical features, such as large-area growth, high uniformity, high reproducibility, ultrathin body, flexibility, and BEOL compatibility, have turned ALD In2O3 into a noteworthy candidate for next-generation oxide semiconductor channel materials.
Effect of probe pulse duration in picosecond ultrasonics
Authors: Liu Yuchen , Yin Jian , Tao Xutang , Yartsev Arkady , Mante Pierre-Adrien
Published: May 2022

Picosecond ultrasonics is a powerful tool for nanoscale metrology, giving access to dimensions and mechanical, thermal, and optical properties of nanomaterials. By monitoring the temporal evolution of the interaction of light with coherent acoustic phonons, also known as Brillouin oscillations, phonon lifetime and optical absorption can be measured. However, the extraction of these quantities can be inaccurate due to the common assumption of the infinite coherence length of probe pulses. Here, we demonstrate the effect of probe pulse duration on picosecond ultrasonic measurements numerically and experimentally. We establish a model that shows how the probe coherence length affects the measured signal loss and how we can overcome this limitation and measure an upper limit of the acoustic attenuation factor. The model is verified experimentally on a GaAs bulk substrate by varying the probe pulse duration, showing a strong effect for sub-100 fs pulses. Finally, we applied to CH3NH3PbBr3, where we reveal a high acoustic attenuation factor, which is in line with recent claims of strong anharmonicity in halide perovskites.
An experimental study of two-layer liquid sloshing under pitch excitations
Authors: Liu Dongming , Wu Yang , Lin Pengzhi
Published: May 2022

The non-resonant and resonant responses of a two-layer liquid system in a tank under pitch excitation were investigated experimentally in this study. The movement of both the free surface and the interface was automatically identified simultaneously by an image processing method, which can rectify the visually tilted frames in a moving system. When the frequency of external excitation was near the natural frequency related to upper layer liquid, free surface resonance can be triggered. On the other hand, when the frequency of the external excitation was close to the natural frequency related to lower layer, resonant response of the interface between two liquids occurred. It is also found that Kelvin-Helmholtz instabilities with different length scales can be generated due to the reverse direction of velocities near the interface under different conditions. Such length scale of the Kelvin–Helmholtz instability can be estimated by using the critical Richardson number. In addition, the bottom of the tank may restrict the development of wave trough on the interface when the depth of lower layer was relatively shallow, while the free surface may limit the wave crest of interface when the thickness of the upper layer was small. Further investigations of the interface displacements for both non-resonant and resonant responses were also conducted in frequency domain.
Sandpile cascades on oscillator networks: The BTW model meets Kuramoto
Authors: Mikaberidze Guram , D’Souza Raissa M.
Published: May 2022

Cascading failures abound in complex systems and the Bak–Tang–Weisenfeld (BTW) sandpile model provides a theoretical underpinning for their analysis. Yet, it does not account for the possibility of nodes having oscillatory dynamics, such as in power grids and brain networks. Here, we consider a network of Kuramoto oscillators upon which the BTW model is unfolding, enabling us to study how the feedback between the oscillatory and cascading dynamics can lead to new emergent behaviors. We assume that the more out-of-sync a node is with its neighbors, the more vulnerable it is and lower its load-carrying capacity accordingly. Also, when a node topples and sheds load, its oscillatory phase is reset at random. This leads to novel cyclic behavior at an emergent, long timescale. The system spends the bulk of its time in a synchronized state where load builds up with minimal cascades. Yet, eventually, the system reaches a tipping point where a large cascade triggers a “cascade of larger cascades,” which can be classified as a dragon king event. The system then undergoes a short transient back to the synchronous, buildup phase. The coupling between capacity and synchronization gives rise to endogenous cascade seeds in addition to the standard exogenous ones, and we show their respective roles. We establish the phenomena from numerical studies and develop the accompanying mean-field theory to locate the tipping point, calculate the load in the system, determine the frequency of the long-time oscillations, and find the distribution of cascade sizes during the buildup phase.
Differentiated transmittance of vortex beams in helical polymer media
Authors: Liu Junhui , Huang Mingju
Published: May 2022

Light beam with helical wavefront, also called optical vortex, carries quantized orbital angular momentum, and as such have many potential photonic applications. In this study, the interaction of a fluorene-based helical polymer thin film with vortex beams was studied. The helicity of the polymeric strands was greatly enhanced by thermal annealing. A liquid crystal phase plate was used to convert TEM00 laser beams into a helical wavefront beam with a phase singularity at its axis. A relatively high absorption dissymmetry was observed in a longer wavelength range, compared with the linear optical absorption of the annealed film sample. The left- and right-handed vortices had different transmittances. The absorption asymmetry of the annealed fluorene film in the case of vortex beams is mainly attributed to quadrupole interactions.
Magnetotransport in graphene nanoribbons sandwiched by superconductors at side edges
Authors: Takagaki Y
Published: May 2022

Magnetotransport properties of the graphene nanoribbons (GNR) that are in contact with superconductors at side edges are investigated numerically with respect to oscillations caused by the cyclotron motion. In terms of the modelling, the superconductors are incorporated as superconducting GNRs to make the Andreev reflection at the graphene-superconductor interface almost perfect. The classical commensurability oscillation appears at low magnetic fields where the cyclotron radius is larger than the width of the nanoribbons. A transition to the circumstance dominated by the quantum interference between Andreev- and normal-reflected components takes place when the Andreev reflection probability is reduced by introducing a barrier at the interface. The near perfection of the Andreev reflection enlarges the period of the oscillation associated with skipping orbits a few orders of magnitude in the quantum limit. Chaotic fluctuations emerge furthermore in the regime of Hofstadter’s butterfly. The periodicity of a transmission modulation at the onset of the chaos is revealed to change continuously over eight orders of magnitude of the magnetic-field variation. The commensurability and edge-state oscillations are examined additionally for the situations with specular Andreev reflection.
High-performance gold/graphene/germanium photodetector based on a graphene-on-germanium wafer
Authors: Jiang Haiyan , Li Bo , Wei Yuning , Feng Shun , Di Zengfeng , Xue Zhongying , Sun Dongming , Liu Chi
Published: May 2022

The metal/germanium (Ge) photodetectors have attracted much attention for their potential applications in on-chip optoelectronics. One critical issue is the relatively large dark current due to the limited Schottky potential barrier height of the metal/germanium junction, which is mainly caused by the small bandgap of Ge and the Fermi energy level pinning effect between the metal and Ge. The main technique to solve this problem is to insert a thin interlayer between the metal and Ge. However, so far, the dark current of the photodetectors is still large when using a bulk-material insertion layer, while when using a two-dimensional insertion layer, the area of the insertion layer is too small to support a mass production. Here, we report a gold/graphene/germanium photodetector with a wafer-scale graphene insertion layer using a 4 inch graphene-on-germanium wafer. The insertion layer significantly increases the potential barrier height, leading to a dark current as low as 1.6 mA cm−2, and a responsivity of 1.82 A W−1 which are the best results for metal/Ge photodetectors reported so far. Our work contributes to the mass production of high-performance metal/Ge photodetectors.
Predictable infrared dual-band narrow-band absorber for infrared detection
Authors: Cui Guicheng , Lv Jizu
Published: May 2022

Dual-band infrared absorbers have received a great deal of attention for their potential applications in the field of sensing and detection. In this paper, we proposed a composite model consisting of Platinum nano-cylinder and micro-ring column stacked on top of Si3N4 and Platinum films. The effect of geometrical parameters on spectral absorption was explored by finite difference in time domain methods, and the results revealed that there were narrow perfect absorption peaks in each of the two atmospheric window bands due to the magnetic polaritons. Meanwhile, the quantitative relationship of resonance wavelength and geometrical parameters were predicted by LC equivalent circuits. In addition, graphene was added to the structure to dynamically adjust the resonance wavelength by varying the Fermi level. The combination of graphene and microstructure achieved full coverage detection of wavelengths in the atmospheric window range. This dual-band absorber has potential applications in infrared detection because of its good absorption properties and its tunability.
Nonlinear functional relation covering near- and far-marginal stability in ion temperature gradient driven turbulence
Authors: Nakayama T , Nakata M , Honda M , Nunami M , Matsuoka S
Published: May 2022

A novel nonlinear functional relation of turbulence potential intensity, zonal flow potential intensity, and ion thermal diffusivity that accurately reproduces nonlinear gyrokinetic simulations of toroidal ion temperature gradient (ITG) driven turbulence is proposed. Applying mathematical optimization techniques to find extremal solutions in high-dimensional parameter space, the optimal regression parameters in the functional form are determined to be valid for both near- and far-marginal regime of the ITG stability including the Dimits-shift. Then, the regression error of ∼5% is accomplished. In addition, it is clarified that the intensity ratio of the zonal flow and turbulence potential intensity is a crucial factor to determine the reproduction accuracy.
Fabrication of anisotropic collagen-based substrates for potential use in tissue engineering
Authors: Tognato Riccardo , Bonfrate Valentina , Giancane Gabriele , Serra Tiziano
Published: May 2022

Stimuli-responsive nanomaterials have the prospective to enable the fabrication of new extracellular matrix-like substrates with unique structures and cell-instructive capabilities. The development of biocompatible collagen substrates with on-demand ordered architectures is an open challenge since it is well-known that the directionality of the collagen fibres affects important cell behaviour, such as proliferation, differentiation, and ultimately, tissue regeneration. Here, an easy and cheap approach to fabricate anisotropic collagen-based substrates exhibiting cells-instructing ability was proposed. Paramagnetic iron oxide nanoparticles (IOPs) coated with polyethylene glycol were synthetized by a coprecipitation and solvothermic method and mixed with a collagen precursors solution. The suspension was then immersed within a static and low-intensity magnetic field to trigger the IOPs self-assembly. Guided by the external stimulus, IOPs assembled along the magnetic field lines into long filamentous structures within the collagen matrix. The solidification of the pre-cursors solution in the presence of filamentous IOPs’ structures promotes the collagen organization into ordered fashions. The obtained collagen substrate demonstrated good cytocompatibility and cells’ instructive properties.
Explainable natural language processing with matrix product states
Authors: Tangpanitanon Jirawat , Mangkang Chanatip , Bhadola Pradeep , Minato Yuichiro , Angelakis Dimitris G , Chotibut Thiparat
Published: May 2022

Despite empirical successes of recurrent neural networks (RNNs) in natural language processing (NLP), theoretical understanding of RNNs is still limited due to intrinsically complex non-linear computations. We systematically analyze RNNs’ behaviors in a ubiquitous NLP task, the sentiment analysis of movie reviews, via the mapping between a class of RNNs called recurrent arithmetic circuits (RACs) and a matrix product state. Using the von-Neumann entanglement entropy (EE) as a proxy for information propagation, we show that single-layer RACs possess a maximum information propagation capacity, reflected by the saturation of the EE. Enlarging the bond dimension beyond the EE saturation threshold does not increase model prediction accuracies, so a minimal model that best estimates the data statistics can be inferred. Although the saturated EE is smaller than the maximum EE allowed by the area law, our minimal model still achieves

∼
99
%

training accuracies in realistic sentiment analysis data sets. Thus, low EE is not a warrant against the adoption of single-layer RACs for NLP. Contrary to a common belief that long-range information propagation is the main source of RNNs’ successes, we show that single-layer RACs harness high expressiveness from the subtle interplay between the information propagation and the word vector embeddings. Our work sheds light on the phenomenology of learning in RACs, and more generally on the explainability of RNNs for NLP, using tools from many-body quantum physics.
Resolving spin currents and spin densities generated by charge-spin interconversion in systems with reduced crystal symmetry
Authors: Camosi Lorenzo , Světlík Josef , Costache Marius V , Savero Torres Williams , Fernández Aguirre Iván , Marinova Vera , Dimitrov Dimitre , Gospodinov Marin , Sierra Juan F , Valenzuela Sergio O
Published: May 2022

The ability to control the generation of spins in arbitrary directions is a long-sought goal in spintronics. Charge to spin interconversion (CSI) phenomena depend strongly on symmetry. Systems with reduced crystal symmetry allow anisotropic CSI with unconventional components, where charge and spin currents and the spin polarization are not mutually perpendicular to each other. Here, we demonstrate experimentally that the CSI in graphene-WTe2induces spins with components in all three spatial directions. By performing multi-terminal nonlocal spin precession experiments, with specific magnetic fields orientations, we discuss how to disentangle the CSI from the spin Hall and inverse spin galvanic effects.
Preparation and properties of ethylene-vinyl acetate grafted acrylonitrile
Authors: Jiang Peng , Huanyan Xu , Zhang Wenlong , Dai Yajie , Liang Yue
Published: May 2022

Ethylene-vinyl acetate copolymer (EVA) was functionalized to varying degrees with acrylonitrile (AN) by melt grafting processes. Fourier transform infrared spectra (FT-IR) confirmed that AN was successfully grafted onto the EVA. High resistance meter, electronic universal testing machine, etc have studied the influencing factors of grafting process and the effect of grafting rate on oil resistance, mechanical properties and electrical properties. The results show that the optimal grafting process is that the dosage of AN is 8.0 wt%, the dosage of styrene (St) is 5.0 wt%, the dosage of Dilauroyl peroxide (LPO) is 0.4 wt% of the total amount of AN and St, and the grafting rate is 1.24%. With the increase of the amount of LPO and AN, the grafting rate first increased and then decreased. The grafting rate increases, so that the oil resistance, volume resistivity, and breakdown field strength of the grafted product are gradually increased. When the grafting rate is 1.24%, the volume resistivity is 1.63 × 1013 Ω·m, which is significantly improved compared with pure EVA, and the breakdown field strength is 23.26 kV mm−1, which is 12.3% higher than pure EVA.
A deformation model and draping behavior analysis of plain weave fabric with low-twist yarn on continuous surface
Authors: Huang Zhaohua , Ma Wensuo , Jia Chenhui , Lei Xianqing , Zhang Zhuangya
Published: May 2022

Fiber-reinforced composites have been widely applied in aerospace, transportation and other industrial applications. An effective method shaping the complex performs is draping plain fabrics on the mandrel surface. However, it is a challenge to realize and predict accurately the deformation of fabric. To establish an accurate deformation mode, plain weave fabrics with low-twist yarn were classified into a stable structure that are not easy to deform and an unstable structures with large deformability based on microstructure characteristics. A variable microstructure unit-cell model has been established to analyze the variation of fabric geometry and performance during deformation. To analyze the draping behavior of fabric with large deformation, a four-node unit was used to mesh the fabric, and then each node on the fabric was mapped to the mandrel surface. The deformation of fabric after draping was simulated by the continuous change of the unit mesh. Analysis results showed that the thickness of preform decreases with the increase of the major-axis of the yarn cross-section, and the formability of fabric increases with the increase of fabric pitch. The accuracy and effectiveness of the geometric mapping method are verified by the fabric drape experiment.
Integer and fractionalized vortex lattices and off-diagonal long-range order
Authors: Rampp Michael A , Schmalian Jörg
Published: May 2022

We analyze the implication of off-diagonal long-range order (ODLRO) for inhomogeneous periodic field configurations and multi-component order parameters. For single component order parameters we show that the only static, periodic field configuration consistent with ODLRO is a vortex lattice with integer flux in units of the flux quantum in each unit cell. For a superconductor with g degenerate components, fractional vortices are allowed. Depending on the precise order-parameter manifold, they tend to occur in units of 1/g of the flux quantum. These results are well known to emerge from the Ginzburg-Landau or BCS theories of superconductivity. Our results imply that they are valid even if these theories no-longer apply. Integer and fractional vortex lattices are transparently seen to emerge as a consequence of the macroscopic coherence and single valuedness of the condensate.
Generation Covid
Authors: Maunder Megan , O'Brien Áine , Reid Jack , Bowman Dominic M , Richards Fred , Gough-Kelly Steven
Published: May 2022

Following a survey on the impact of the pandemic on early-career researchers, Megan Maunder, Áine O'Brien, Jack Reid, Dominic M. Bowman, Fred Richards and Steven Gough-Kelly sift the data from Generation Covid.
Building the biggest galaxies
Authors: Davison Thomas
Published: May 2022

Steady advances in observational and theoretical astrophysics have led to the conclusion that massive galaxies form ‘inside out’. Thomas Davison describes simulations of the fraction of stars that formed in situ and ex situ.
Assessing and assuring interoperability of a genomics file format
Authors: Niu Yi Nian , Roberts Eric G , Denisko Danielle , Hoffman Michael M
Published: May 2022

Motivation

Bioinformatics software tools operate largely through the use of specialized genomics file formats. Often these formats lack formal specification, making it difficult or impossible for the creators of these tools to robustly test them for correct handling of input and output. This causes problems in interoperability between different tools that, at best, wastes time and frustrates users. At worst, interoperability issues could lead to undetected errors in scientific results.

Results

We developed a new verification system, Acidbio, which tests for correct behavior in bioinformatics software packages. We crafted tests to unify correct behavior when tools encounter various edge cases—potentially unexpected inputs that exemplify the limits of the format. To analyze the performance of existing software, we tested the input validation of 80 Bioconda packages that parsed the Browser Extensible Data (BED) format. We also used a fuzzing approach to automatically perform additional testing. Of 80 software packages examined, 75 achieved less than 70% correctness on our test suite. We categorized multiple root causes for the poor performance of different types of software. Fuzzing detected other errors that the manually designed test suite could not. We also created a badge system that developers can use to indicate more precisely which BED variants their software accepts and to advertise the software’s performance on the test suite.

Availability and implementation

Acidbio is available at https://github.com/hoffmangroup/acidbio.

Supplementary information

Supplementary data are available at Bioinformatics online.
An R package VIGoR for joint estimation of multiple linear learners with variational Bayesian inference
Authors: Onogi Akio , Arakawa Aisaku
Published: May 2022

An R package that can implement multiple linear learners, including penalized regression and regression with spike and slab priors, in a single model has been developed. Solutions are obtained with fast minorize-maximization algorithms in the framework of variational Bayesian inference. This package helps to incorporate multimodal and high-dimensional explanatory variables in a single regression model.

Availability and implementation

The R package VIGoR (Variational Bayesian Inference for Genome-wide Regression) is available at the Comprehensive R Archive Network (CRAN) (https://cran.r-project.org/) and at GitHub (https://github.com/Onogi/VIGoR).

Supplementary information

Supplementary data are available at Bioinformatics online.