bluuebunny/crossref_metadata_2025 huggingface dataset:
Simulating microgravity using a random positioning machine for inducing cellular responses to mechanotransduction in human osteoblasts
Authors: Wubshet Nadab H. , Arreguin-Martinez Esmeralda , Nail Mark , Annamalai Hariprasad , Koerner Robert , Rousseva Maria , Tom Tristan , Gillespie R. Brent , Liu Allen P.
Published: November 2021

The mechanotransduction pathways that mediate cellular responses to contact forces are better understood than those that mediate response to distance forces, especially the force of gravity. Removing or reducing gravity for significant periods of time involves either sending samples to space, inducing diamagnetic levitation with high magnetic fields, or continually reorienting samples for a period, all in a manner that supports cell culturing. Undesired secondary effects due to high magnetic fields or shear forces associated with fluid flow while reorienting must be considered in the design of ground-based devices. We have developed a lab-friendly and compact random positioning machine (RPM) that fits in a standard tissue culture incubator. Using a two-axis gimbal, it continually reorients samples in a manner that produces an equal likelihood that all possible orientations are visited. We contribute a new control algorithm by which the distribution of probabilities over all possible orientations is completely uniform. Rather than randomly varying gimbal axis speed and/or direction as in previous algorithms (which produces non-uniform probability distributions of orientation), we use inverse kinematics to follow a trajectory with a probability distribution of orientations that is uniform by construction. Over a time period of 6 h of operation using our RPM, the average gravity is within 0.001 23% of the gravity of Earth. Shear forces are minimized by limiting the angular speed of both gimbal motors to under 42 °/s. We demonstrate the utility of our RPM by investigating the effects of simulated microgravity on adherent human osteoblasts immediately after retrieving samples from our RPM. Cytoskeletal disruption and cell shape changes were observed relative to samples cultured in a 1 g environment. We also found that subjecting human osteoblasts in suspension to simulated microgravity resulted in less filamentous actin and lower cell stiffness.
Tight conformation of 2-bridge knots using superhelices
Authors: Huh Youngsik , Kim Hyoungjun , Oh Seungsang
Published: November 2021

The ropelength is a mathematical quantity that regulates the tightness of flexible strands in the three-dimensional space. The superhelical conformation of long twisted strands is known to be more efficient in terms of ropelength compared with the circular double helical conformation. In this paper, we present a conformation of 2-bridge knots by using ropelength-minimizing superhelical curves and derive an upper bound on the ropelength of 2-bridge knots. Our superhelical model of 2-bridge knots is shown to be more efficient than the standard double helical one if the iterative twisted parts are long enough.
Boron-nitride foam composite resonators
Authors: Ben-Shimon Yahav , Reddy Siva K. , Ya'akobovitz Assaf
Published: November 2021

While boron-nitride foam (BNF) has shown remarkable properties, such as large surface area, wide bandgap, and high chemical and thermal stability, its realization as a resonator is a critical step toward its implementation into sensors, ultraviolet optical devices, and high-power systems. Here, we demonstrate BNF composite resonators. We first characterized the response of the resonators under mechanical loading, followed by their resonance excitation under the influence of Kelvin polarization force. In parallel, we built a model that clarifies the trends in the operation of our resonators. We found that the Kelvin polarization force induces a stiffening of the resonators, which allows resonance frequency tuning. Also, the Kelvin polarization force enables the excitation of BNF composites from a distance, while eliminating the need for high-precision fabrication and electrical wiring. Therefore, we uncover the fundamental physical behavior of BNF and pave the path toward its integration into advanced functional devices.
The Robin problem on rectangles
Authors: Rudnick Zeév , Wigman Igor
Published: November 2021

We study the statistics and the arithmetic properties of the Robin spectrum of a rectangle. A number of results are obtained for the multiplicities in the spectrum depending on the Diophantine nature of the aspect ratio. In particular, it is shown that for the square, unlike the case of Neumann eigenvalues where there are unbounded multiplicities of arithmetic origin, there are no multiplicities in the Robin spectrum for a sufficiently small (but nonzero) Robin parameter except a systematic symmetry. In addition, uniform lower and upper bounds are established for the Robin–Neumann gaps in terms of their limiting mean spacing. Finally, the pair correlation function of the Robin spectrum on a Diophantine rectangle is shown to be Poissonian.
An algebraic approach of non-self-adjoint Hamiltonians in Krein spaces
Authors: Inoue Hiroshi
Published: November 2021

Through our series of studies, we have constructed some physical operators such as non-self-adjoint Hamiltonians H, lowering operators A, and raising operators B and their adjoint H†, A†, and B† from generalized Riesz systems. However, we cannot consider the *-algebraic structure of their operators because even the sum H + H† is not well-defined. Our purpose of this paper is to introduce the *-algebra structure of all their operators by defining a certain Krein space.
Atomic transport properties of liquid iron at conditions of planetary cores
Authors: Li Qing , Sun Tao , Zhang Yi-gang , Xian Jia-Wei , Vočadlo Lidunka
Published: November 2021

Atomic transport properties of liquid iron are important for understanding the core dynamics and magnetic field generation of terrestrial planets. Depending on the sizes of planets and their thermal histories, planetary cores may be subject to quite different pressures (P) and temperatures (T). However, previous studies on the topic mainly focus on the P–T range associated with the Earth’s outer core; a systematic study covering conditions from small planets to massive exoplanets is lacking. Here, we calculate the self-diffusion coefficient D and viscosity η of liquid iron via ab initio molecular dynamics from 7.0 to 25 g/cm3 and 1800 to 25 000 K. We find that D and η are intimately related and can be fitted together using a generalized free volume model. The resulting expressions are simpler than those from previous studies where D and η were treated separately. Moreover, the new expressions are in accordance with the quasi-universal atomic excess entropy (Sex) scaling law for strongly coupled liquids, with normalized diffusivity D⋆ = 0.621 exp(0.842Sex) and viscosity η⋆ = 0.171 exp(−0.843Sex). We determine D and η along two thermal profiles of great geophysical importance: the iron melting curve and the isentropic line anchored at the ambient melting point. The variations of D and η along these thermal profiles can be explained by the atomic excess entropy scaling law, demonstrating the dynamic invariance of the system under uniform time and space rescaling. Accordingly, scale invariance may serve as an underlying mechanism to unify planetary dynamos of different sizes.
Origins of oscillatory dynamics in the model of reactive oxygen species in the rhizosphere
Authors: Maćešić Stevan , Tóth Ágota , Horváth Dezső
Published: November 2021

Oscillatory processes are essential for normal functioning and survival of biological systems, and reactive oxygen species have a prominent role in many of them. A mechanism representing the dynamics of these species in the rhizosphere is analyzed using stoichiometric network analysis with the aim to determine its capabilities to simulate various dynamical states, including oscillations. A detailed analysis has shown that unstable steady states result from four destabilizing feedback cycles, among which the cycle involving hydroquinone, an electron acceptor, and its semi-reduced form is the dominant one responsible for the existence of saddle-node and Andronov–Hopf bifurcations. This requires a higher steady-state concentration for the reduced electron acceptor compared to that of the remaining species, where the level of oxygen steady-state concentration determines whether the Andronov–Hopf or saddle-node bifurcation will occur.
Evolution of epsilon-near-zero plasmon with surface roughness and demonstration of perfect absorption in randomly rough indium tin oxide thin films
Authors: Goswami Sumit , Kumar Sharma Ashwini , Biswas Subrata , Alagarsamy Perumal
Published: November 2021

Any degree of surface roughness could play a significant role in determining the optical properties of ultra-thin films required for epsilon-near-zero (ENZ) applications. In this report, we have provided a systematic analysis of the evolution of an ENZ mode with increasing surface roughness values and established both experimentally and theoretically that roughness acts as a supporting mechanism for achieving a strong ENZ plasmon resonance response in randomly rough indium tin oxide thin films. For pulsed laser deposited indium tin oxide thin films, ENZ plasmon-mediated absorption is enhanced monotonically with the increasing surface roughness. A value of 99.75%, depicting near-perfect absorption, at a wavelength of 1335 nm for the incidence angle of 50° is demonstrated experimentally via Kretschmann–Raether configuration for the film with the highest surface roughness. A modified transfer matrix method based on the anisotropic Bruggemann effective medium approximation is being used to effectively simulate the experimental spectra, and based on this analysis, an even higher absorption is predicted at lower angles outside the experimentally viable domain. Such a high value of absorption just above the ENZ wavelength is due to the strong electric field enhancement inside the film layer, while in terms of absorption loss, surface roughness leads the way and contributes immensely toward the occurrence of perfect absorption in the collective media. Modification of the ENZ mode dispersion in the presence of a surface roughness layer is also discussed, and observed perfect absorption is recognized as the outcome of the crossover between the internal damping and radiation damping terms.
An investigation of horizontal and vertical flow boiling in a single channel with a confinement number beyond the threshold of micro-scale flow
Authors: Saisorn Sira , Suriyawong Adirek , Srithumkhant Pochai , Wongpromma Pakorn , Wongwises Somchai
Published: November 2021

The gravitational force effect is of concern when designing flow boiling systems deployed on Earth and in space. A study of the R-134a flow boiling inside the horizontal and vertical channels was experimentally performed to explore the flow orientations' effect on flow pattern and heat transfer characteristics. The test section was a 0.5 mm diameter tube from which the corner effect was excluded. The single channel was used to avoid disturbances that flow maldistribution could possibly cause in the multiple channels. The experimental two-phase flow corresponded to a 1.75 confinement number, which was above the threshold for micro-scale flow. The results indicated the flow regime map, which was less affected by the channel orientation except for that slug flow pattern that was unable to survive during the vertical downflow and vertical upflow. Also, based on the present micro-scale flow, the heat transfer results were mostly independent of the gravitational force effect, and the nucleate boiling and convective mechanisms tended to govern them.
Fluid modeling of inductively coupled iodine plasma for electric propulsion conditions
Authors: Levko Dmitry , Raja Laxminarayan L.
Published: November 2021

Iodine is being studied as an alternative propellant for electric propulsion application as it has numerous advantages over commonly used xenon gas. In spite of numerous experimental studies for the conditions typical for electric propulsion, there are very few computational modeling studies of iodine plasmas: all with reduced geometric representations in zero or one dimension. In the present paper, we use self-consistent two-dimensional fluid model coupled with Maxwell's equations to analyze the inductively coupled plasma generated in low-pressure iodine. We compare the plasma parameters for two values of the background pressure: 1.0 and 2.5 Pa. We find that ∼99% of the molecular iodine is converted into atomic iodine. As a result, plasma consists of electrons, ions I+, and a significant number of negative ions I−. The density of molecular ions I2+ is much smaller than the density of I+. We analyze the transport of these species for two pressures and show that there are different regimes of plasma diffusion realized for the conditions of our studies. We also study how the discharge power influences the plasma parameters such as the electron and ion densities and the electron temperature.
Transient growth in a flat plate boundary layer under a stream with uniform shear
Authors: Gopalakrishnan Shyam Sunder , Mandal Alakesh Chandra
Published: November 2021

One of the simplest problems involving external vorticity in boundary layer flows is the flow over a semi-infinite plate under a stream of uniform shear. We study the transient growth phenomenon in this flow to investigate the role of freestream shear on energy amplification and analyze the differences with the Blasius flow. The initial optimal disturbance that triggers the maximum growth is found to be streamwise vortices, as in other shear flows. Compared to the Blasius boundary layer, higher optimum energy and larger spanwise wavelength of streamwise vortices have been observed. We provide scaling laws for the maximum optimal amplification, which is found to increase exponentially with the freestream shear gradient.
Computational spectroscopy of complex systems
Authors: Jansen Thomas L. C.
Published: November 2021

Numerous linear and non-linear spectroscopic techniques have been developed to elucidate structural and functional information of complex systems ranging from natural systems, such as proteins and light-harvesting systems, to synthetic systems, such as solar cell materials and light-emitting diodes. The obtained experimental data can be challenging to interpret due to the complexity and potential overlapping spectral signatures. Therefore, computational spectroscopy plays a crucial role in the interpretation and understanding of spectral observables of complex systems. Computational modeling of various spectroscopic techniques has seen significant developments in the past decade, when it comes to the systems that can be addressed, the size and complexity of the sample types, the accuracy of the methods, and the spectroscopic techniques that can be addressed. In this Perspective, I will review the computational spectroscopy methods that have been developed and applied for infrared and visible spectroscopies in the condensed phase. I will discuss some of the questions that this has allowed answering. Finally, I will discuss current and future challenges and how these may be addressed.
Observing halogen-bond-assisted electron transport in high-performance polymer solar cells
Authors: Hu Haixia , Fu Lulu , Zhang Kangning , Gao Kun , Ma Jing , Hao Xiaotao , Yin Hang
Published: November 2021

It is a broad agreement that a balance of the electron/hole mobility ratio mainly affects the device performance of organic solar cells. However, this consensus is still a semi-empirical model, rather than a universal principle with strict proof. Here, we evaluate the effects of hole/electron mobility ratios to device performance from the literature and four typical bulk-heterojunction systems. The results indicate that balanced hole/electron mobilities may not be a necessary and sufficient condition to high-performance polymer solar cells statistically, although the device performance may also appear to exist with clear mobility-ratio dependence in many reports. We propose a clear correlation between the electron hopping distance and fill factor in solar cells, rather than the absolute mobility values. In the high-performance PM6:BTP-eC9 device, an electron hopping distance of 2.98 Å can be observed, which is even much shorter than the π–π stacking distance in such a film. A halogen-bond-assisted charge transport model is proposed and correlated with the device performance from molecular dynamics simulations, and it provides a perspective to understand the device physics and charge transport in organic solar cells.
A “Janus” double sided mid-IR photodetector based on a MIM architecture
Authors: Malerba Mario , Jeannin Mathieu , Pirotta Stefano , Li Lianhe , Davies Alexander Giles , Linfield Edmund , Bousseksou Adel , Manceau Jean-Michel , Colombelli Raffaele
Published: November 2021

We present a mid-IR (λ ∼ 8.3 μm) quantum well infrared photodetector (QWIP) fabricated on a mid-IR transparent substrate, allowing photodetection with illumination from either the front surface or through the substrate. The device is based on a 400 nm-thick GaAs/AlGaAs semiconductor QWIP heterostructure enclosed in a nanostructured metal–insulator–metal cavity and hosted on a mid-IR transparent ZnSe substrate. Metallic stripes are symmetrically patterned by e-beam lithography on both sides of the active region. The detector spectral coverage spans from λ ∼ 7.15 to λ ∼ 8.7 μm by changing the stripe width L—from L = 1.0 to L = 1.3 μm—thus frequency-tuning the optical cavity mode. Both micro-FTIR passive optical characterizations and photocurrent measurements of the two-port system are carried out. They reveal a similar spectral response for the two detector ports with an experimentally measured TBLIP of ∼200 K.
Active matter in infinite dimensions: Fokker–Planck equation and dynamical mean-field theory at low density
Authors: Arnoulx de Pirey Thibaut , Manacorda Alessandro , van Wijland Frédéric , Zamponi Francesco
Published: November 2021

We investigate the behavior of self-propelled particles in infinite space dimensions by comparing two powerful approaches in many-body dynamics: the Fokker–Planck equation and dynamical mean-field theory. The dynamics of the particles at low densities and infinite persistence time is solved in the steady state with both methods, thereby proving the consistency of the two approaches in a paradigmatic out-of-equilibrium system. We obtain the analytic expression for the pair distribution function and the effective self-propulsion to first-order in the density, confirming the results obtained in a previous paper [T. Arnoulx de Pirey et al., Phys. Rev. Lett. 123, 260602 (2019)] and extending them to the case of a non-monotonous interaction potential. Furthermore, we obtain the transient behavior of active hard spheres when relaxing from the equilibrium to the nonequilibrium steady state. Our results show how collective dynamics is affected by interactions to first-order in the density and point out future directions for further analytical and numerical solutions of this problem.
Molecular dynamics simulation of metallic Al–Ce liquids using a neural network machine learning interatomic potential
Authors: Tang L. , Ho K. M. , Wang C. Z.
Published: November 2021

Al-rich Al–Ce alloys have the possibility of replacing heavier steel and cast irons for use in high-temperature applications. Knowledge about the structures and properties of Al–Ce alloys at the liquid state is vital for optimizing the manufacture process to produce desired alloys. However, reliable molecular dynamics simulation of Al–Ce alloy systems remains a great challenge due to the lack of accurate Al–Ce interatomic potential. Here, an artificial neural network (ANN) deep machine learning (ML) method is used to develop a reliable interatomic potential for Al–Ce alloys. Ab initio molecular dynamics simulation data on the Al–Ce liquid with a small unit cell (∼200 atoms) and on the known Al–Ce crystalline compounds are collected to train the interatomic potential using ANN-ML. The obtained ANN-ML model reproduces well the energies, forces, and atomic structure of the Al90Ce10 liquid and crystalline phases of Al–Ce compounds in comparison with the ab initio results. The developed ANN-ML potential is applied in molecular dynamics simulations to study the structures and properties of the metallic Al90Ce10 liquid, which would provide useful insight into the guiding experimental process to produce desired Al–Ce alloys.
Turbulent field fluctuations in gyrokinetic and fluid plasmas
Authors: Mathews A. , Mandell N. , Francisquez M. , Hughes J. W. , Hakim A.
Published: November 2021

A key uncertainty in the design and development of magnetic confinement fusion energy reactors is predicting edge plasma turbulence. An essential step in overcoming this uncertainty is the validation in accuracy of reduced turbulent transport models. Drift-reduced Braginskii two-fluid theory is one such set of reduced equations that has for decades simulated boundary plasmas in experiment, but significant questions exist regarding its predictive ability. To this end, using a novel physics-informed deep learning framework, we demonstrate the first ever direct quantitative comparisons of turbulent field fluctuations between electrostatic two-fluid theory and electromagnetic gyrokinetic modeling with good overall agreement found in magnetized helical plasmas at low normalized pressure. This framework presents a new technique for the numerical validation and discovery of reduced global plasma turbulence models.
Evidence of supercoolable nanoscale water clusters in an amorphous ionic liquid matrix
Authors: Pabst Florian , Kraus Jennifer , Kloth Sebastian , Steinrücken Elisa , Kruteva Margarita , Radulescu Aurel , Vogel Michael , Blochowicz Thomas
Published: November 2021

Nanoscale water clusters in an ionic liquid matrix, also called “water pockets,” were previously found in some mixtures of water with ionic liquids containing hydrophilic anions. However, in these systems, at least partial crystallization occurs upon supercooling. In this work, we show for mixtures of 1-butyl-3-methylimidazolium dicyanamide with water that none of the components crystallizes up to a water content of 72 mol. %. The dynamics of the ionic liquid matrix is monitored from above room temperature down to the glass transition by combining depolarized dynamic light scattering with broadband dielectric and nuclear magnetic resonance spectroscopy, revealing that the matrix behaves like a common glass former and stays amorphous in the whole temperature range. Moreover, we demonstrate by a combination of Raman spectroscopy, small angle neutron scattering, and molecular dynamics simulation that, indeed, nanoscale water clusters exist in this mixture.
Effects of 29Si and 1H on the near-zero field magnetoresistance response of Si/SiO2 interface states: Implications for oxide tunneling currents
Authors: Frantz Elias B. , Michalak David J. , Harmon Nicholas J. , Henry Eric M. , Flatté Michael E. , King Sean W. , Clarke James S. , Lenahan Patrick M.
Published: November 2021

We report on a study that offers fundamental physical insight into an important phenomenon in solid state device physics, tunneling in Si/SiO2. We observe near-zero field magnetoresistance via spin-dependent trap-assisted-tunneling in both unpassivated and passivated Si/SiO2 and 28Si/28SiO2 metal–insulator–semiconductor (MIS) capacitors. A previous report, which utilized electrically detected magnetic resonance and NZFMR on these devices, indicates a surprising conclusion: the observed trap-assisted tunneling spectra are dominated by silicon dangling bonds back bonded to silicon at the Si/SiO2 interface, Pb0 and Pb1 centers. In this study, the four sets of samples are virtually identical, apart from the presence or absence of either 1H and 29Si. We observed a substantial narrowing of the NZFMR response with the removal of 29Si nuclei and a substantial broadening with the addition of 1H. Since superhyperfine interactions between 29Si nuclei Pb at the Si/SiO2 interface are a full order of magnitude stronger than such interactions involving silicon dangling bonds defects (E′ centers) within the oxide, the NZFMR results strongly suggest a response dominated by Si/SiO2 interface trap defects. With the introduction of 1H magnetic nuclei to the interface after a forming gas anneal, linewidths and lines shapes of Si/SiO2 and 28Si/28SiO2 MIS capacitors were nearly identical. However, the amplitude of the NZFMR response is greatly reduced by the introduction of hydrogen by a fraction about equal to the reduction in the interface trap density. Our results further indicate that the rate limiting step in trap-assisted tunneling is the interface to oxide trapping event.
Bismuth layer properties in the ultrathin Bi–FeNi multilayer films probed by spectroscopic ellipsometry
Authors: Kovaleva N. N. , Chvostova D. , Pacherova O. , Muratov A. V. , Fekete L. , Sherstnev I. A. , Kugel K. I. , Pudonin F. A. , Dejneka A.
Published: November 2021

Using wideband (0.5–6.5 eV) spectroscopic ellipsometry, we study ultrathin [Bi(0.6–2.5 nm)–FeNi(0.8,1.2 nm)]N multilayer films grown by rf sputtering deposition, where the FeNi layer has a nanoisland structure and its morphology and magnetic properties change with decreasing the nominal layer thickness. From multilayer model simulations of the ellipsometric angles, Ψ(ω) and Δ(ω), complex (pseudo)dielectric function spectra of the Bi layer were extracted. The obtained results demonstrate that the Bi layer can possess the surface metallic conductivity, which is strongly affected by the morphology and magnetic properties of the nanoisland FeNi layer in GMR-type Bi–FeNi multilayer structures.
Structural and vibrational characterization of HCO+ and Rg–HCO+, Rg = {He, Ne, Ar, Kr, and Xe}
Authors: Tan Jake A. , Teh Soon , Kuo Jer-Lai
Published: November 2021

The structures of the formyl ion (HCO+) and its rare gas tagged counterparts (Rg–HCO+, Rg = He, Ne, Ar, Kr, and Xe) were studied at the coupled-cluster singles, doubles, and perturbative triples [CCSD(T)]/aug-cc-pVTZ level of theory and basis set. A linear structure for these tagged complexes was predicted. The Rg binding energies for Rg–HCO+ are also examined at the CCSD(T) level. It was found that the binding interaction increases from He–HCO+ to Xe–HCO+. A multilevel potential energy surface built at the CCSD(T) and second-order Møller–Plesset perturbation levels of theory were used to study these species’ vibrational spectra. By changing the Rg in the first-solvation shell for HCO+, the Fermi resonance interaction between the first H+ bend overtone and the asymmetric and symmetric H–C–O stretches can be modulated. This Fermi resonance modulation is demonstrated by examining a series of rare gas solvated HCO+.
Broadband vibration attenuation achieved by additively manufactured 3D rainbow hollow sphere foams
Authors: Meng Han , Elmadih Waiel , Jiang Huan , Lawrie Tristan , Chen Yanyu , Chronopoulos Dimitrios
Published: November 2021

This paper investigates dynamic properties of 3D rainbow lightweight hollow sphere foams both numerically and experimentally. Two rainbow hollow sphere foams are designed with linearly varying sphere shell thicknesses and binder diameters for the purpose of achieving broadband vibration attenuation at low frequencies. The hollow sphere foams are modeled by the finite element method. The band structures of two rainbow hollow sphere foams are compared with that of the uniform foam. The results show that the foam with gradient binders exhibits a bandgap more than two times broader than that of the uniform foam at lower frequencies, and the gradient binders also lead to locally concentrated vibration modes at the bandgap edges, which are different from the global vibration modes of the uniform foam. On the other hand, the foam with gradient shell thickness could not generate complete bandgaps due to the introduced additional modes by the varied shell thickness. The bandgap extension could, hence, be realized with properly designed structural gradients of foams. The rainbow and uniform hollow sphere foam samples are manufactured subsequently by the additive manufacturing method and tested with a frequency response function measurement system. The experimental results verify the numerical calculation as well as prove further the effects of gradient designs on bandgap extension. The proposed rainbow hollow sphere foams could be instructive for future researchers to design lightweight acoustic/dynamic structures for broadband low frequency noise and vibration control.
Breakdown of the ionization potential theorem of density functional theory in mesoscopic systems
Authors: Nazarov Vladimir U.
Published: November 2021

The ionization potential (IP)-theorem of Kohn–Sham (KS) density functional theory (DFT) states that the energy of the highest occupied molecular orbital (HOMO) ϵHOMO equals the negative of the first IP, thus ascribing a physical meaning to one of the eigenvalues of the KS Hamiltonian. We scrutinize the fact that the validity of the IP-theorem relies critically on the electron density n(r), far from the system, to be determined by HOMO only, behaving as n(r)∼r→∞e−2−2ϵHOMOr. While this behavior always holds for finite systems, it does not hold for mesoscopic ones, such as quasi-two-dimensional (Q2D) electron gas or Q2D crystals. We show that this leads to the violation of the IP-theorem for the latter class of systems. This finding has a strong bearing on the role of the KS valence band with respect to the work-function problem in the mesoscopic case. Based on our results, we introduce a concept of the IP band structure as an observable alternative to its unphysical KS counterpart. A practical method of the determination of the IP band structure in terms of DFT quantities is provided.
On the asymptotic matching procedure predicting the formation number
Authors: Limbourg Raphaël , Nedić Jovan
Published: November 2021

A detailed review of the asymptotic matching procedures predicting the formation number of vortex rings is presented. The original studies of Mohseni and Gharib [“A model for universal timescale of vortex ring formation,” Phys. Fluids 10(10), 2436–2438 (1998).], Shusser and Gharib [“A new model for inviscid vortex rings,” in 30th AIAA Fluid Dynamical Conference (1999).], and Linden and Turner [“The formation of ‘optimal’ vortex rings, and the efficiency of propulsion devices,” J. Mech. Fluids, 427, 61–72 (2001).] are applied to the extended slug-flow model for orifice starting jets and the Kaplanski model of isolated vortex rings. A predicted formation number of 3.5 in the modified non-dimensional time frame is found when the closure assumption in terms of the translational ring speed is chosen, which is consistent with experimental evidence. In addition, particle image velocimetry was performed to assess the validity of the closure assumptions of Mohseni and Gharib and Shusser and Gharib. First, it was further demonstrated that the modified slug-flow model provides an appropriate scaling for the kinematics of orifice-generated vortex rings. Second, the measurements provide experimental support to the method of Shusser and Gharib rather than the method of Mohseni and Gharib. This is further demonstrated by data extracted from the literature. To summarize, in order to predict the formation number, it is recommended to use the extended slug-flow model and the Kaplanski model of isolated vortex rings along with the closure assumption of Shusser and Gharib.
Exciton–polaritons in GaAs-based slab waveguide photonic crystals
Authors: Whittaker C. E. , Isoniemi T. , Lovett S. , Walker P. M. , Kolodny S. , Kozin V. , Iorsh I. V. , Farrer I. , Ritchie D. A. , Skolnick M. S. , Krizhanovskii D. N.
Published: November 2021

We report the observation of bandgaps for low loss exciton–polaritons propagating outside the light cone in GaAs-based planar waveguides patterned into two-dimensional photonic crystals. By etching square lattice arrays of shallow holes into the uppermost layer of our structure, we open gaps on the order of 10 meV in the photonic mode dispersion, whose size and light–matter composition can be tuned by proximity to the strongly coupled exciton resonance. We demonstrate gaps ranging from almost fully photonic to highly excitonic. Opening a gap in the exciton-dominated part of the polariton spectrum is a promising first step toward the realization of quantum-Hall-like states arising from topologically nontrivial hybridization of excitons and photons.
How does the wind generate waves?
Authors: Pizzo Nick , Deike Luc , Ayet Alex
Published: November 2021

Although the question is a classical problem, the details of how wind transfers energy to waves at the ocean surface remain elusive.
Resistance mechanisms and expression of disease resistance-related genes in sugarcane (
Authors: Hidayah Nurul , McNeil Meredith , Li Jingchuan , Bhuiyan Shamsul , Galea Victor , Aitken Karen
Published: November 2021

Resistance of sugarcane (Saccharum officinarum L.) to smut disease (caused by Sporisorium scitamineum) is driven by two separate mechanisms, external and internal resistance. Two progenies generated from an introgression cross, with contrasting responses to smut infection were used to investigate this interaction. Histopathological screening at different stages of the plant growth was used to determine the extent of mycelium growth within sugarcane tissues. Ten disease resistance-related genes were selected, and the relative expression determined using quantitative real-time reverse transcription PCR (real-time RT-qPCR). The results revealed that PR10, HCT1 and ScChi were down-regulated in the susceptible progeny and up-regulated in the resistant progeny early infection process. This may reflect an early attempt to halt pathogen development by increasing the lignin deposition at the infection site. At 8 weeks post-inoculation, they were highly up-regulated in the susceptible progeny coincided with whip development. This reveals a major role for these genes to whip development in the susceptible progeny and indicates that while PR10 is involved in the resistance mechanism of resistant progeny early infection process it also has a role in susceptibility. These results on genetically related progeny with different responses to smut infection reveal a complex interaction of genes and gene networks being induced in response to fungal invasion.
Phase separation in fluids with many interacting components
Authors: Shrinivas Krishna , Brenner Michael P.
Published: November 2021

Significance

Immiscible fluids are found everywhere—examples include vinaigrette and ouzo in the kitchen, multiphase hydrocarbon–water mixtures common in oil extraction, and in virtually all living things. Within the living cell, thousands of biomolecules organize into multiple coexisting liquid-like phases that enable diverse functions. Despite their ubiquity in nature and industry, how numerous interactions between components encode their macroscopic multiphase behavior remains poorly understood. We employ statistical physics approaches to reveal the emergent dynamical, compositional, and steady-state properties of coexisting phases in fluid mixtures with many randomly interacting components. Building on these findings, we demonstrate design strategies to encode linear or nonmonotonic scaling relationships between the number of phases and components and suggest active routes to tunably modify multiphase coexistence.
Mass spectrometric identification of immunogenic SARS-CoV-2 epitopes and cognate TCRs
Authors: Pan Ke , Chiu Yulun , Huang Eric , Chen Michelle , Wang Junmei , Lai Ivy , Singh Shailbala , Shaw Rebecca M. , MacCoss Michael J. , Yee Cassian
Published: November 2021

Significance

Durable protection against COVID-19 infection may be achieved by generating robust T cell responses to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and emerging SARS-CoV-2 variants; for those infected, effective treatments are urgently needed. For these strategies to be successful, accurate identification of T cell epitopes is critical. In this study, we used major histocompatibility complex immune precipitation, acid elution, and tandem mass spectrometry to define the SARS-CoV-2 immunopeptidome for membrane glycoprotein (MGP) and the nonstructural protein. Furthermore, taking advantage of a highly robust endogenous T cell workflow, we verify the immunogenicity of these MS-defined peptides by in vitro generation of MGP and NSP13 peptide-specific T cells and confirm T cell recognition of MGP or NSP13 endogenously expressing cell lines.
Countering linguistic violence by place-making in the public space
Authors: Sabri Malika , Blackwood Robert
Published: November 2021

Much is discussed in the literature about the Arabization of Algeria’s public space since its independence from France in
1962. This privileging of the contest between Arabic and French eclipses the stake claimed by speakers of Tamazight, the Afro-Asiatic
language spoken by the majority in the historic province of Kabylia, to the east of the capital Algiers. Taking the wilaya
of Tizi-Ouzou, in the heart of Kabylia, as the focus for this article, we adopt a performative approach to exploring the making of place,
and in particular a Tamazightophone space, by triangulating traditional Linguistic Landscape data, interviews with residents, and 200 years
of competing language management strategies. In response to the linguistic violence perpetrated by French colonial powers and aggressive
Arabisation policies, we investigate how the discourses of place, particularly Amazigh cultural and linguistic identity, challenge the
double erasure of Tamazight.
Na doping into Li-rich layered single crystal nanoparticles for high-performance lithium-ion batteries cathodes
Authors: Li Jili , Lin Haiyan , Tang Chunjuan , Yu Dongsheng , Sun Jie , Zhang Wanzhen , Wang Yujiang
Published: November 2021

Lithium-rich layered manganese-based cathodes (LRLMOs) with first-class energy density (∼1000 W h kg−1) have attracted wide attention. Nevertheless, the weak cycle stability and bad rate capability obstruct their large-scale commercial application. Here, single crystal Li1.2−x
Na
x
Ni0.2Mn0.6O2 (x = 0, 0.05, 0.1, 0.15) nanoparticles are designed and successfully synthesized due to the single crystal structure with smaller internal stress and larger ionic radius of Na. The synergistic advantages of single crystal structure and Na doping are authenticated as cathodes for Li ion batteries (LIBs), which can consolidate the crystallographic structure and be benefit for migration of lithium ion. Among all the Na doping single crystals, Li1.1Na0.1Ni0.2Mn0.6O2 cathode possesses supreme cycling life and discharge capacity at large current density. To be more specific, it exhibits a discharge capacity of 264.2 mAh g–1 after 50 charge and discharge cycles, higher than that of undoped material (214.9 mAh g–1). The discharge capacity of Li1.1Na0.1Ni0.2Mn0.6O2 cathode at 10 C (1 C = 200 mA g−1) is enhanced to 160.4 mAh g−1 (106.7 mAh g–1 for x = 0 sample). The creative strategy of Na doping single crystal LRLMOs might furnish an idea to create cathode materials with high energy and power density for next generation LIBs.
Anomalous two-photon Compton scattering
Authors: Kettle B , Aquila A , Boutet S , Bucksbaum P H , Carini G , Feng Y , Gamboa E , Ghimire S , Glenzer S , Hart P , Hastings J B , Henighan T , Hunter M , Koglin J , Kozina M , Liu H , MacDonald M J , Trigo M , Reis D A , Fuchs M
Published: November 2021

X-ray free-electron lasers can generate radiation pulses with extreme peak intensities at short wavelengths. This enables the investigation of laser–matter interactions in a regime of high fields, yet at a non-relativistic ponderomotive potential, where ordinary rules of light–matter interaction may no longer apply and nonlinear processes are starting to become observable. Despite small cross-sections, first nonlinear effects in the hard x-ray regime have recently been observed in solid targets, including x-ray-optical sum-frequency generation (XSFG), x-ray second harmonic generation (XSHG) and two-photon Compton scattering (2PCS). Nonlinear interactions of bound electrons in the x-ray range are fundamentally different from those dominating at optical frequencies. Whereas in the optical regime nonlinearities are predominantly caused by anharmonicities of the atomic potential in the chemical bonds, x-ray nonlinearities far above atomic resonances are expected to be due to nonlinear oscillations of quasi-free electrons, including inner-shell atomic electrons. While the quasi-free-electron model agrees reasonably well with the experimental data for XSFG and XSHG, 2PCS measurements have led to unexpected results: the energy of the nonlinearly scattered photons from non-relativistic electrons shows a substantial unexpected red shift in addition to the Compton shift that is well beyond that predicted by a nonlinear quantum electrodynamics model for free electrons.

A potential explanation for the spectral broadening is based on a previously unexplored scattering process that involves the whole atom rather than just quasi-free electrons. A first simulation that includes the atomic binding potential was successful in describing a broadening of the spectrum of the nonlinearly scattered photons to longer wavelengths for soft x-rays. However, the same model does not show any broadening at hard x-ray wavelengths, which is in agreement with other simulation approaches. To this point no calculation has been able to reproduce the experimentally observed broadening.

Here we present further experimental data of 2PCS for an extended parameter range using additional diagnostics. In particular, we present measurements of the electron momentum distribution during the interaction that strongly suggest that the spectral broadening is not caused by an increased plasma temperature. We extend our measurement of the magnitude of the red shift in beryllium to

>
1.9

k
e
V

in addition to the Compton shift expected for free electrons and expand the measurement of the angular distribution to include forward scattering angles. We also present first measurements of 2PCS from diamond.
The W. Thurston algorithm applied to real polynomial maps
Authors: Bonifant Araceli , Milnor John , Sutherland Scott
Published: November 2021

This note will describe an effective procedure for constructing critically finite real polynomial maps with specified combinatorics.
Influence of rainfall on foraging behavior of a tropical seabird
Authors: De Pascalis Federico , Austin Rhiannon E , Green Jonathan A , Arnould John P Y , Imperio Simona , Maugeri Maurizio , Haakonsson Jane , Cecere Jacopo G , Rubolini Diego
Published: November 2021

Acquiring resources for self-maintenance and reproduction is a key challenge for wild animals, and the methods that individuals employ are, in part, shaped by environmental conditions that vary in time and space. For birds, rainfall may affect behavior, impairing senses and increasing energetic costs, but its consequences on movement patterns are poorly explored. We investigated the influence of rainfall on the foraging behavior of the magnificent frigatebird, Fregata magnificens. This peculiar tropical seabird lacks feather waterproofing and is known to track environmental conditions while searching for food. Thus, its foraging behavior should be highly sensitive to the effects of rainfall. By GPS-tracking chick-rearing adults, we showed that frigatebirds did not avoid areas with rainfall during foraging trips, nor did rainfall influence trip characteristics. However, rainfall decreased time devoted to foraging and increased time spent perching. Moreover, it affected flight mode, inducing birds to fly slower and at lower altitudes. Wind speed, which was not correlated with rainfall, only affected behavior during night-time, with strong winds decreasing time spent perching. Our results indicate that rainfall does not affect the spatial distribution of foraging frigatebirds but does alter fine-scale foraging behavior by reducing flight activity. We suggest that the ongoing environmental change in this region, including an increase in rainfall events, has the potential to impair foraging and negatively affect fitness.
Hepatic vein resection and reconstruction for liver malignancies: expanding indication and enhancing parenchyma-sparing hepatectomy
Authors: Kawano Fumihiro , Mise Yoshihiro , Yamamoto Junji , Oba Atsushi , Ono Yoshihiro , Sato Takafumi , Inoue Yosuke , Ito Hiromichi , Takahashi Yu , Saiura Akio
Published: November 2021

The short-term outcomes after hepatic vein reconstruction (HVR) were evaluated in 41 patients. HVR can be performed safely using autologous vein graft. HVR can increase the functional remnant liver volume, facilitating parenchyma-sparing one-step hepatectomy as well as expanding resectability even in patients with all major hepatic veins involved.
Study on the corrosion of refractory materials by coal blended with the extraction residue of direct coal liquefaction in a simulated gasification atmosphere
Authors: Peng Baozi , Zhao Shixian , Liu Zhen
Published: November 2021

Utilizing the extraction residue (ER) of direct coal liquefaction residue as a gasification feedstock has significant economic value. But the characteristic of high ash and iron in the ER would increase the risk of corrosion of the refractory materials and affect the long-term operation of the gasifier. In this work, corrosion experiments of molten slag derived from a mixture of 20 wt% ER and 80 wt% coal on a high-chromia refractory brick and SiC brick were carried out using a rotary-drum furnace in a simulated gasification atmosphere. The experimental results show that the viscosity of the poured slag is larger as compared to the initial ash sample at the same temperature, which suggests that the viscosity–temperature relationship of the poured slag should be used as the reference for the operation temperature of the gasifier to ensure that the slag can flow during operation. For a high-chromia refractory brick, iron oxides in molten slag could react with Cr2O3 in the refractory matrix but, because the aggregate was not found to be damaged, the damage to the matrix structure was the key factor for causing the corrosion of the high-chromia refractory brick. Metallic iron was observed in the exposed SiC brick, which indicated that the reaction between the iron oxides in the slag and SiC occurred, forming metallic iron and SiO2. The corrosion of a SiC brick by molten slag depended mainly on the dissolution of Al2O3 particles and the reaction between iron oxides in the molten slag and SiC particles. Therefore, the high iron content in coal ash had a serious influence on the corrosion of refractory materials. More efforts need to be made on coal blended with ER as a gasification feedstock in the future.