bluuebunny/crossref_metadata_2025 huggingface dataset:
Perturbed distribution functions with accurate action estimates for the Galactic disc
Authors: Al Kazwini H. , Agobert Q. , Siebert A. , Famaey B. , Monari G. , Rozier S. , Ramos P. , Ibata R. , Gausland S. , Rivière C. , Spolyar D.
Published: November 2021

In the Gaia era, understanding the effects of the perturbations of the Galactic disc is of major importance in the context of dynamical modelling. In this theoretical paper we extend previous work in which, making use of the epicyclic approximation, the linearized Boltzmann equation had been used to explicitly compute, away from resonances, the perturbed distribution function of a Galactic thin-disc population in the presence of a non-axisymmetric perturbation of constant amplitude. Here we improve this theoretical framework in two distinct ways in the new code that we present. First, we use better estimates for the action-angle variables away from quasi-circular orbits, computed from the AGAMA software, and we present an efficient routine to numerically re-express any perturbing potential in these coordinates with a typical accuracy at the per cent level. The use of more accurate action estimates allows us to identify resonances such as the outer 1:1 bar resonance at higher azimuthal velocities than the outer Lindblad resonance, and to extend our previous theoretical results well above the Galactic plane, where we explicitly show how they differ from the epicyclic approximation. In particular, the displacement of resonances in velocity space as a function of height can in principle constrain the 3D structure of the Galactic potential. Second, we allow the perturbation to be time dependent, thereby allowing us to model the effect of transient spiral arms or a growing bar. The theoretical framework and tools presented here will be useful for a thorough analytical dynamical modelling of the complex velocity distribution of disc stars as measured by past and upcoming Gaia data releases.
The iron and oxygen content of LMC Classical Cepheids and its implications for the extragalactic distance scale and Hubble constant
Authors: Romaniello Martino , Riess Adam , Mancino Sara , Anderson Richard I. , Freudling Wolfram , Kudritzki Rolf-Peter , Macrì Lucas , Mucciarelli Alessio , Yuan Wenlong
Published: November 2021

Context. Classical Cepheids are primary distance indicators and a crucial stepping stone in determining the present-day value of the Hubble constant H0 to the precision and accuracy required to constrain apparent deviations from the ΛCDM Concordance Cosmological Model.

Aims. We measured the iron and oxygen abundances of a statistically significant sample of 89 Cepheids in the Large Magellanic Cloud (LMC), one of the anchors of the local distance scale, quadrupling the prior sample and including 68 of the 70 Cepheids used to constrain H0 by the SH0ES program. The goal is to constrain the extent to which the luminosity of Cepheids is influenced by their chemical composition, which is an important contributor to the uncertainty on the determination of the Hubble constant itself and a critical factor in the internal consistency of the distance ladder.

Methods. We derived stellar parameters and chemical abundances from a self-consistent spectroscopic analysis based on equivalent width of absorption lines.

Results. The iron distribution of Cepheids in the LMC can be very accurately described by a single Gaussian with a mean [Fe/H] = −0.409 ± 0.003 dex and σ = 0.076 ± 0.003 dex. We estimate a systematic uncertainty on the absolute mean values of 0.1 dex. The width of the distribution is fully compatible with the measurement error and supports the low dispersion of 0.069 mag seen in the near-infrared Hubble Space Telescope LMC period–luminosity relation. The uniformity of the abundance has the important consequence that the LMC Cepheids alone cannot provide any meaningful constraint on the dependence of the Cepheid period–luminosity relation on chemical composition at any wavelength. This revises a prior claim based on a small sample of 22 LMC Cepheids that there was little dependence (or uncertainty) between composition and near-infrared luminosity, a conclusion which would produce an apparent conflict between anchors of the distance ladder with different mean abundance. The chemical homogeneity of the LMC Cepheid population makes it an ideal environment in which to calibrate the metallicity dependence between the more metal-poor Small Magellanic Cloud and metal-rich Milky Way and NGC 4258.
Investigation on the interfacial properties of CNTs sized carbon fibres in epoxy resin using push-out method via nano-indentation technique
Authors: Zhang Zhenxue , Li Xiaoying , Dong Hanshan , Jestin Simon , Termine Stefania , Trompeta Aikaterini-Flora , Araújo Andreia , Santos Raquel M. , Charitidis Costas
Published: November 2021

In this work, the carbon fibres (CFs) surfaces were modified via sizing and coated with a very thin layer of a complex formulation including carbon nanotubes (CNTs). A push-out method was developed based on nanoindentation to assess the interfacial shear strength of the fibre/matrix. The mechanical properties such as indentation hardness, reduced modulus, indentation displacement and indentation creep of the composite were evaluated by means of the Oliver-Pharr method. The critical load of different composites was measured and the interfacial shear strength (IFSS) was calculated to compare the effect of the CNTs concentration in the sizing solution. Wettability evaluation of the sized fibres was performed prior to nanoindentation to investigate the adhesion of the resin. After push-out testing, characterisation by optical microscopy/SEM was carried out to ratify the results. It was found sizing with a small amount of evenly distributed nano-inclusion on CFs can increase the interfacial shear strength but large amount of sizing could lead to a decrease of the interfacial bonding due to the agglomeration of CNTs on CFs.
Organic dyes as corrosion inhibitors of commercial AA1050 aluminum alloy in sodium chloride environment
Authors: Pantazopoulou Paraskevi , Theohari Stamatina , Kalogeropoulou Sofia
Published: November 2021

Considering corrosion control of aluminum is of great technical, economic, environmental and aesthetical importance, the use of inhibitors is one of the promising solutions for protecting aluminum and its alloys against corrosion. The research about green corrosion inhibitors which are environmentally friendly and do not contain heavy metals or other toxic compounds has gained a large interest. This study is an effort to investigate the role of a natural organic dye, Crocin, against the corrosion of a commercial aluminum alloy AA1050, in an aggressive chloride ions environment of NaCl 0,01M, in comparison with a synthetic dye, Alphazurine A. Corrosion behavior of AA1050 specimens in NaCl 0,01M solution at room temperature was studied by investigating their electrochemical behavior in the absence and presence of the two organic dyes, using DC Corrosion techniques, Linear Polarization and Tafel Polarization. The effect of the organic dyes as corrosion inhibitors was also evaluated by mass loss measurements. Study and characterization of the morphology of the surface of the specimens, before and after the corrosion measurements, was performed using Scanning Electron Microscopy. Results obtained showed that the examined dyes have a protective action against corrosion of aluminum surface in the corrosive environment.
Putting Stiffness where it’s needed: Optimizing the Mechanical Response of Multi-Material Structures
Authors: Mounchili Arouna Patouossa , Bosse Stefan , Lehmhus Dirk , Struss Adrian
Published: November 2021

Manufacturing processes are increasingly adapted to multi-material part production to facilitate lightweight design via improvement of structural performance. The difficulty lies in determining the optimum spatial distribution of the individual materials. Multi-Phase Topology Optimization (MPTO) achieves this aim via iterative, linear-elastic Finite Element (FE) simulations providing element- and part-level strain energy data under a given design load and using it to redistribute predefined material fractions to minimize total strain energy. The result us a part configuration offering maximum stiffness. The present study implements different material redistribution and optimization techniques and compares them in terms of optimization results and performance: Genetic algorithms are matched against simulated annealing, the latter with and without physics-based constraints. Both types employ partial randomization in generating new configurations to avoid settling into local rather than global minima of the objective function. This allows exploring a larger fraction of the full search space than accessed by classic gradient-based algorithms. Evaluation of the objective function depends on FE simulation, a computationally intensive task. Minimizing the required number of simulation runs is the task of the aforementioned constraints. The methodology is validated via a three point bending test scenario.
On the effects of heat and surface treatment on the fatigue performance of high-strength leaf springs
Authors: Malikoutsakis Michail , Gakias Christos , Makris Ioannis , Kinzel Peter , Müller Eckehard , Pappa Maria , Michailidis Nikolaos , Savaidis Georgios
Published: November 2021

Leaf springs constitute the most effective suspension way of commercial vehicle axles from the cost and maintainability point of view. Especially in case of front axles, they overtake both the guidance and suspension functions, which consequently designates them as safety components, whose pre-mature failure is explicitly prohibited. The present paper deals with the fatigue performance of downsized parabolic leaf specimens made of the high-strength spring steel 51CrV4 under serial manufacturing conditions. It focuses on the influence of the major manufacturing steps, i.e. the heat treatment and the subsequently applied stress shot peening. The effectiveness of the applied heat treatment on the microstructure transformation and the extent of surface decarburization is determined by means of optical microscopy and corresponding microstructural analyses. Comprehensive series of constant amplitude fatigue tests are executed before and after the applied stress shot peening to quantify its effectiveness on the fatigue performance. The tests cover two characteristic stress ratios of operational significance with the complete range of interest being experimentally investigated. Additionally, surface residual stresses measurements together with micro- and macro-hardness and roughness values before and after stress shot peening are executed to expose the influence of each individual technological effect on the overall fatigue performance.
Approximation of elastic-plastic local strains in surface-hardened notched components
Authors: Yadegari Patrick , Schlitzer Teresa , Vormwald Michael
Published: November 2021

Elastic-plastic strains at points relevant for structural failures are usually approximated using formulas based on the stresses determined by elasticity theory. For this purpose, the Neuber approximation is a common method to estimate the local elastic-plastic strains in the notch root, although this is currently only approved for homogeneous components. For surfacehardened notched components, these approximation formulas need to be modified to cover two potential failure points: The notch root as well as the interface between the stronger surface layer and the weaker core material. In the following, a multi-step algorithm is shown that allows the estimation of elastic-plastic local strains at these two points, based on a single elasticitytheoretical solution. A comparison of the approximated values with those from finite element analyses (FEA) reveals that this results in only minor inaccuracies, while the usability is remarkable.
Practical Experience with the Methodology of Prediction of Corrosion-Fatigue Failures of Steam Turbine Rotating Blades
Authors: Kasl Josef , Lazar Jan , Matějová Miroslava
Published: November 2021

Corrosion fatigue fractures initiating from corrosion pits are one of the most serious problem during service of rotating blades of the low-pressure parts of steam turbines. A methodology for fatigue failure prediction, originally based on the knowledge obtained by EPRI (Electric Power Research Institute), using corrosion pits parameters assessment and local stresses calculation was adapted to the conditions of ČEZ a.s. power stations. This contribution deals with the evaluation of the corrosion state of blades of three low pressure rotors after long service. Measurement was done in power stations equipped with turbines of power 200 MW and 110 MW respectively. Possibilities and uncertainties (influence of filling of pits with oxides, cyclic stress calculations, and the selection of the geometric factor Y) and their elimination are discussed.
Grenzen einer neurootologisch-psychosomatischen Tinnitus
Spezialambulanz
Authors: Schaaf Helmut , Kastellis Georg , Hesse Gerhard
Published: November 2021

Grenzen einer neurootologisch-psychosomatischen Tinnitus Spezialambulanz Wenn
auch eine neurootologische psychosomatische Tinnitus Spezialambulanz nicht
weitergeholfen hat

Ziel Patienten mit einem Leiden an Tinnitus
fühlen sich oft in ihrer Not nicht ausreichend verstanden und
beklagen, dass ihnen ein Besuch beim Arzt oder Therapeuten nicht
weitergeholfen habe. Dies liegt auch an der Verknüpfung der
organischen Grundlagen für den Tinnitus mit zahlreichen psychischen
Faktoren, die an der Aufrechterhaltung des Leidens am Tinnitus beteiligt
sind. In einer spezialisierten Ambulanz sollten sowohl der neurootologische
als auch der psychosomatische Anteil angemessen aufgegriffen werden
können, so dass den Tinnitus- Patienten ein solcher Besuch
weiterhelfen sollte. Hier sollen die Größenordnung und
mögliche Gründe dafür, dass ein Besuch nicht
weitergeholfen hat, untersucht werden.

Material und
Methode Nachuntersucht wurden 295 von 699 einmalig ambulant gesehenen
Patienten, die mit dem Symptom Tinnitus eine Spezialambulanz aufsuchten.
Dabei wurden Hörbefunde erstellt sowie der Mini-Tinnitus-Fragebogen
(TF 12) nach Hiller und Goebel 1 zur
Symptombelastung und die deutschsprachige Version des Hospitality Anxiety
and Depression Score (HADS) 2 zur
Abschätzung der Angst- und der Depressionskomponente eingesetzt.
Frühestens 6 Monate später, durchschnittlich nach 32
Monaten, wurden die Patienten gebeten, einen ihnen zugeschickten Fragebogen,
u. a. mit der Frage: „Der Besuch hat mir nicht
weitergeholfen“, sowie erneut den Mini-TF (TF 12) und den HADS
auszufüllen. Ergebnisse: 42 Patienten (14%) gaben an, dass
ihnen der Besuch nicht weitergeholfen habe. Bei diesen zeigten sich
– trotz des erfolgten Counsellings – weder Verbesserungen im
TF12 noch im HADS. Sie fühlten sich deutlich weniger verstanden und
setzten eklatant weniger um als die Patienten, die angaben, dass ihnen der
Besuch geholfen habe. Als Hauptgründe dafür, dass der Besuch
nicht weitergeholfen hat, wurden das Beharren auf somatischen
Lösungen (40%) und die Nichtumsetzung von indizierten
psychotherapeutischen Maßnahmen vermutet (26%).

Schlussfolgerung Grundlage einer Tinnitus-Behandlung ist
ein neurootologisch fundiertes Counselling. Dennoch kann dies als nicht
weiterhelfend empfunden werden. Dies kann Gründe beim Patienten,
beim Behandler und in deren Interaktion
haben.
How Inclusive are the Local Economic Impacts of Social Protection in Uganda?
Authors: Kuss Maria Klara , Gassmann Franziska , Mugumya Firminus
Published: November 2021

Inclusive growth and development are essential for the sustainability of poverty reduction and growth. Social protection has been promoted as part of the inclusive growth and development agenda by emphasising the positive impacts of social transfers on people’s participation in economic processes. However, the focus on the positive economic impacts of social transfers has led to the neglect of concerns regarding inequality of opportunity. Taking the case of Uganda’s Senior Citizens Grant, this paper critically assesses how inclusive the impacts of social transfers are on economic processes. This is done by examining the extent to which local economic structures interplay with the impacts of the Grant. Based on a qualitative case study design, the analysis reveals that the scheme has unwittingly reinforced spatial patterns of economic exclusion and disadvantage. Recipients in remote areas are more likely to stay or fall back into poverty compared to people in integrated areas. For social transfers to contribute to inclusive growth and development for all, it will be vital to invest in complementary development interventions in economically disadvantaged areas.
Predicting red blood cell response to mechanical loads
Authors: Cockshott Anne
Published: November 2021

Red blood cells change shape during circulation in response to tensile and shear stress
A new force-measuring balance for large-scale model in hypersonic wind tunnel
Authors: Wang Qinchao , Li Shichao , Gao Hongli , Lv Jinzhou , Zhang Xiaoqing , Liu Weixiong , Liu Zihao
Published: November 2021

There is a strong coupling effect between the body and propulsion system of the integrated hypersonic vehicle. The scaled-down model cannot reflect the laws of physics. Therefore, carrying out hypersonic aerodynamic tests using large-scale aircraft models is an urgent difficulty and the key link in the research of hypersonic aircraft. This Note presents a design scheme of large-scale and heavy-load three-component gauge strain balance. The balance innovatively uses the design of a “herringbone” force measuring element and a support plate to ensure the sensitivity of the main channel and solve the problem of serious coupling between channels. In order to solve the problem of insufficient stiffness caused by the large scale of the model, two convex plates are added to the contact surface between the model and the balance. Therefore, the difficulties encountered by large-scale aircraft models in a pulsed wind tunnel can be overcome effectively. The balance is verified by static calibration and wind tunnel test to meet the requirements. The results show that the balance meets the requirements of the aerodynamic load test of the large-scale and heavy-duty hypersonic vehicle model in a pulse combustion wind tunnel.
Selective decay for the rotating shallow-water equations with a structure-preserving discretization
Authors: Brecht Rüdiger , Bauer Werner , Bihlo Alexander , Gay-Balmaz François , MacLachlan Scott
Published: November 2021

Numerical models of weather and climate critically depend on the long-term stability of integrators for systems of hyperbolic conservation laws. While such stability is often obtained from (physical or numerical) dissipation terms, physical fidelity of such simulations also depends on properly preserving conserved quantities, such as energy, of the system. To address this apparent paradox, we develop a variational integrator for the shallow water equations that conserves energy but dissipates potential enstrophy. Our approach follows the continuous selective decay framework [F. Gay-Balmaz and D. Holm. Selective decay by Casimir dissipation in inviscid fluids. Nonlinearity, 26(2), 495 (2013)], which enables dissipating an otherwise conserved quantity while conserving the total energy. We use this in combination with the variational discretization method [Pavlov et al., “Structure-preserving discretization of incompressible fluids,” Physica D 240(6), 443–458 (2011)] to obtain a discrete selective decay framework. This is applied to the shallow water equations, both in the plane and on the sphere, to dissipate the potential enstrophy. The resulting scheme significantly improves the quality of the approximate solutions, enabling long-term integrations to be carried out.
Equation of State for Solid Benzene Valid for Temperatures up to 470 K and Pressures up to 1800 MPa
Authors: Xiao Xiong , Trusler J. P. Martin , Yang Xiaoxian , Thol Monika , Al Ghafri Saif Z. S. , Rowland Darren , May Eric F.
Published: November 2021

The thermodynamic property data for solid phase I of benzene are reviewed and utilized to develop a new fundamental equation of state (EOS) based on Helmholtz energy, following the methodology used for solid phase I of CO2 by Trusler [J. Phys. Chem. Ref. Data 40, 043105 (2011)]. With temperature and molar volume as independent variables, the EOS is able to calculate all thermodynamic properties of solid benzene at temperatures up to 470 K and at pressures up to 1800 MPa. The model is constructed using the quasi-harmonic approximation, incorporating a Debye oscillator distribution for the vibrons, four discrete modes for the librons, and a further 30 distinct modes for the internal vibrations of the benzene molecule. An anharmonic term is used to account for inevitable deviations from the quasi-harmonic model, which are particularly important near the triple point. The new EOS is able to describe the available experimental data to a level comparable with the likely experimental uncertainties. The estimated relative standard uncertainties of the EOS are 0.2% and 1.5% for molar volume on the sublimation curve and in the compressed solid region, respectively; 8%–1% for isobaric heat capacity on the sublimation curve between 4 K and 278 K; 4% for thermal expansivity; 1% for isentropic bulk modulus; 1% for enthalpy of sublimation and melting; and 3% and 4% for the computed sublimation and melting pressures, respectively. The EOS behaves in a physically reasonable manner at temperatures approaching absolute zero and also at very high pressures.
Hyperspectral CARS microscopy and quantitative unsupervised analysis of deuterated and non-deuterated fatty acid storage in human cells
Authors: Boorman Dale , Pope Iestyn , Masia Francesco , Langbein Wolfgang , Hood Steve , Borri Paola , Watson Peter
Published: November 2021

Coherent anti-Stokes Raman scattering (CARS) implemented as a vibrational micro-spectroscopy modality eradicates the need for potentially perturbative fluorescent labeling while still providing high-resolution, chemically specific images of biological samples. Isotopic substitution of hydrogen atoms with deuterium introduces minimal change to molecular structures and can be coupled with CARS microscopy to increase chemical contrast. Here, we investigate HeLa cells incubated with non-deuterated or deuterium-labeled fatty acids, using an in-house-developed hyperspectral CARS microscope coupled with an unsupervised quantitative data analysis algorithm, to retrieve Raman susceptibility spectra and concentration maps of chemical components in physically meaningful units. We demonstrate that our unsupervised analysis retrieves the susceptibility spectra of the specific fatty acids, both deuterated and non-deuterated, in good agreement with reference Raman spectra measured in pure lipids. Our analysis, using the cell-silent spectral region, achieved excellent chemical specificity despite having no prior knowledge and considering the complex intracellular environment inside cells. The quantitative capabilities of the analysis allowed us to measure the concentration of deuterated and non-deuterated fatty acids stored within cytosolic lipid droplets over a 24 h period. Finally, we explored the potential use of deuterium-labeled lipid droplets for non-invasive cell tracking, demonstrating an effective application of the technique for distinguishing between cells in a mixed population over a 16 h period. These results further demonstrate the chemically specific capabilities of hyperspectral CARS microscopy to characterize and distinguish specific lipid types inside cells using an unbiased quantitative data analysis methodology.
Spiral waves in a hybrid discrete excitable media with electromagnetic flux coupling
Authors: Rajagopal Karthikeyan , He Shaobo , Duraisamy Prakash , Karthikeyan Anitha
Published: November 2021

Though there are many neuron models based on differential equations, the complexity in realizing them into digital circuits is still a challenge. Hence, many new discrete neuron models have been recently proposed, which can be easily implemented in digital circuits. We consider the well-known FitzHugh–Nagumo model and derive the discrete version of the model considering the sigmoid type of recovery variable and electromagnetic flux coupling. We show the various time series plots confirming the existence of periodic and chaotic bursting as in differential equation type neuron models. Also, we have used the bifurcation plots, Lyapunov exponents, and frequency bifurcations to investigate the dynamics of the proposed discrete neuron model. Different topologies of networks like single, two, and three layers are considered to analyze the wave propagation phenomenon in the network. We introduce the concept of using energy levels of nodes to study the spiral wave existence and compare them with the spatiotemporal snapshots. Interestingly, the energy plots clearly show that when the energy level of nodes is different and distributed, the occurrence of the spiral waves is identified in the network.
Modeling and simulation of transitional Rayleigh–Taylor flow with partially averaged Navier–Stokes equations
Authors: Pereira F. S. , Grinstein F. F. , Israel D. M. , Rauenzahn R. , Girimaji S. S.
Published: November 2021

The partially averaged Navier–Stokes (PANS) equations are used to predict the variable-density Rayleigh–Taylor (RT) flow at Atwood number 0.5 and maximum Reynolds number 500. This is a prototypical problem of material mixing, featuring laminar, transitional, and turbulent flow, instabilities and coherent structures, density fluctuations, and production of turbulence kinetic energy by both shear and buoyancy mechanisms. These features pose numerous challenges to modeling and simulation, making the RT flow ideal to develop the validation space of the recently proposed PANS Besnard–Harlow–Rauenzahn-linear eddy viscosity model closure. The numerical simulations are conducted at different levels of physical resolution and test three approaches to set the parameters fϕ defining the range of physically resolved scales. The computations demonstrate the efficiency (accuracy vs cost) of the PANS model predicting the spatiotemporal development of the RT flow. Results comparable to large-eddy simulations and direct numerical simulations are obtained at significantly lower physical resolution without the limitations of the Reynolds-averaged Navier–Stokes equations in these transitional flows. The data also illustrate the importance of appropriate selection of the physical resolution and the resolved fraction of each dependent quantity ϕ of the turbulent closure, fϕ. These two aspects determine the ability of the model to resolve the flow phenomena not amenable to modeling by the closure and, as such, the computations' fidelity.
Investigation of flow dynamics of thin viscous films down differently shaped fibers
Authors: Xie Qirui , Liu Rong , Wang Xun , Chen Xue
Published: November 2021

The flow dynamics of a thin viscous film down on a fiber is associated with a variety of industrial applications. In this paper, we experimentally investigate the flow behaviors of a thin film falling on differently shaped fibers. For a spiral fiber, flow behaviors show three typical flow regimes as the cylindrical fiber, which indicates the isolated regime, Rayleigh–Plateau regime, and convective regime. However, the transition process of various fiber shapes is distinctively different. Unlike the cylindrical fiber, flow on a spiral fiber exhibits a wider range of flow rate in the Rayleigh–Plateau regime, which is helpful for the precise control of flow patterns in a relatively stable regime. We further quantitatively investigate three important characteristic parameters of flow dynamics of a spiral fiber, i.e., bead velocity, thickness, and spacing. Results reveal that a thin film on a spiral fiber has a higher bead velocity, larger bead thickness, and larger bead spacing. Our findings provide important insights for understanding flow dynamics of a thin viscous film down on shaped fibers, which may also inspire coating flow control methods in various applications.
Formation and deformation mechanisms in gradient nanostructured NiCoCrFe high entropy alloys upon supersonic impacts
Authors: Wang Zhihua , Zhang Tuanwei , Tang Enling , Xiong Renlong , Jiao Zhiming , Qiao Junwei
Published: November 2021

Bulk large-gradient nanostructured NiCoCrFe high-entropy alloys with millimeter-scale gradient layer were prepared by supersonic Taylor impact. The microstructure evolution over a wide range of strain rates (10−3–105/s) was characterized, and the formation mechanism of nanocrystals with well-defined boundaries at high strain rate (>104/s) was identified to be the emerging, thickening, and mutual intersection of lattice rotation bands, high-density dislocation bands, and deformation twins. This Letter not only reveals the deformation mechanisms of high entropy alloys under a wide range of strain rates but also provides an idea that could be applied to the preparation of bulk gradient nanostructured materials.
On monotonic stability of elliptic pipe flow
Authors: Demyanko Kirill V. , Klyushnev Nikita V.
Published: November 2021

It was previously shown that the linear stability of fluid flows in pipes significantly depends on their cross-sectional aspect ratio. The linear stability analysis allows for judging the asymptotic behavior of the basic flow disturbances; however, it says nothing about their possible transient growth, which can cause the so-called subcritical laminar–turbulent transition. The lower limit of the Reynolds numbers at which the growth of the kinetic energy of disturbances is possible is the energy critical Reynolds number. In the present work, for the Poiseuille flow in a pipe of axially uniform elliptic cross-section the dependence of the energy critical Reynolds number on the pipe aspect ratio A is computed for 1≤A≤5, based on the energy stability method. The dependence is non-monotonic under scaling providing the same flow rates at the same Reynolds numbers. In particular, at A≈2.3 the critical Reynolds number reaches its maximum, but then monotonically decreases with increasing A, becoming less than in a circular pipe, and tends to the energy critical Reynolds number of the plane Poiseuille flow under an appropriate scaling as A→∞. A qualitative explanation of the obtained dependence is proposed based on the analysis of the critical disturbances corresponding to the critical Reynolds number and their kinetic energy balance. The obtained dependence suggests that the change in the pipe aspect ratio may be a promising tool for the passive control of the laminar–turbulent transition in pipe flows and can be used together with other known approaches employed for this purpose.
Quantitative prediction of elongation deformation and shape relaxation of a red blood cell under tensile and shear stresses
Authors: Wu Chenbing , Wang Shuo , Qi Xiaojing , Yan Weiwei , Li Xuejin
Published: November 2021

The characteristic time of stress relaxation is a key viscoelastic property of cell membrane that controls time-dependent processes such as shape recovery. Although many experimental studies have been devoted to the measurement of characteristic relaxation time, considerable uncertainty still stands because existing methods rely on different experimental designs and analyses. Here, we present a mesoscopic computational study to investigate the elastic deformation and relaxation characteristics of an isolated red blood cell (RBC) under both tensile and shear stresses. We examine the elastic response and relaxation behavior of the RBC under static tensile stretching and dynamic shear stress. When the cell deformation index responding fluid shear stress is equivalent to the one responding external tensile stretching, we find that the characteristic relaxation time for the RBC in planar flows is longer than that for the RBC under tensile stretching. We also subject the RBC to confined tube/channel flows to probe the effect of geometric confinement on its elastic deformation and relaxation dynamics. Our simulations show that the computed characteristic relaxation time is further increased when compared to those obtained under tensile stretching or planar flows, indicating that the confinement would slow down the cell relaxation process, especially under strong confinement conditions. These findings may facilitate a better understanding of variable relaxation time observed in different experiments.
The role of bandwidth in setting the breaking slope threshold of deep-water focusing wave packets
Authors: Pizzo Nick , Murray Ethan , Smith David Llewellyn , Lenain Luc
Published: November 2021

We examine the role of wave packet bandwidth in modulating the breaking slope threshold for focusing deep-water surface gravity wave packets. Using a fully nonlinear potential flow solver and laboratory experiments, we show that the slope threshold may be strongly modulated by the wave packet bandwidth. We propose a new breaking threshold parameterization that shows that the slope threshold may be modulated by more than a factor of two by changes in the bandwidth. This has implications for parameterizations of the properties of the breaking induced flow (e.g., the energy dissipation) as they do not currently account for these effects.
Influence of LRE (Ce, Y, and La) on microstructure and magnetic properties of (Nd0.8LRE0.2)–Fe–B hot-deformed magnets
Authors: Milov Y. , Tang Xin , Sepehri-Amin H. , Sysoev N. N. , Ohkubo T. , Hono K.
Published: November 2021

To develop low-cost, high-performance light rare earth element (LRE)-substituted Nd–Fe–B permanent magnets, we systematically studied the effect of substituting Nd with 20% light rare earth elements (LRE = Ce, Y, and La) on the hard magnetic properties of (Nd0.8LRE0.2)–Fe–B hot-deformed magnets. The (Nd0.8Ce0.2)2Fe14B magnet showed a coercivity of μ0Hc = 1.41 T, which is comparable to that of an LRE-free magnet. Y substitution was found to decrease μ0Hc and μ0Mr to 1.22 and 1.32 T, respectively, as was expected from the intrinsic properties of (Nd0.8Y0.2)2Fe14B. Unlike our expectation, the thermal stability of coercivity is not degraded by the Y substitution, demonstrating its potential for elevated temperature applications. With La substitution, coercivity is substantially degraded to 0.67 T because of the low intrinsic properties and the lack of the intergranular phase. The Y and Ce co-substituted (Nd0.8Ce0.1Y0.1)2Fe14B hot-deformed magnets showed better thermal stability of coercivity compared to the (Nd0.8Ce0.2)2Fe14B sample.
Molecular phylogeny of the orb-weaving spider genus Leucauge and the intergeneric relationships of Leucauginae (Araneae, Tetragnathidae)
Authors: Ballesteros Jesús A. , Hormiga Gustavo
Published: November 2021

The tetragnathid genus Leucauge includes some of the most common orb-weaving spiders in the tropics. Although some species in this genus have attained relevance as model systems for several aspects of spider biology, our understanding of the generic diversity and evolutionary relationships among the species is poor. In this study we present the first attempt to determine the phylogenetic structure within Leucauge and the relationship of this genus with other genera of Leucauginae. This is based on DNA sequences from the five loci commonly used and Histone H4, used for the first time in spider phylogenetics. We also assess the informativeness of the standard markers and test for base composition biases in the dataset. Our results suggest that Leucauge is not monophyletic since species of the genera Opas, Opadometa, Mecynometa and Alcimosphenus are included within the current circumscription of the genus. Based on a phylogenetic re-circumscription of the genus to fulfil the requirement for monophyly of taxa, Leucauge White, 1841 is deemed to be a senior synonym of the genera Opas Pickard-Cambridge, 1896 revalidated synonymy, Mecynometa Simon, 1894 revalidated synonymy, Opadometa Archer, 1951 new synonymy and Alcimosphenus Simon, 1895 new synonymy. We identify groups of taxa critical for resolving relationships within Leucauginae and describe the limitations of the standard loci for accomplishing these resolutions.
Lipofuscin causes atypical necroptosis through lysosomal membrane permeabilization
Authors: Pan Chendong , Banerjee Kalpita , Lehmann Guillermo L. , Almeida Dena , Hajjar Katherine A. , Benedicto Ignacio , Jiang Zhichun , Radu Roxana A. , Thompson David H. , Rodriguez-Boulan Enrique , Nociari Marcelo M.
Published: November 2021

Significance

Retinal lipofuscin causes retinal pigment epithelium cell death in Stargardt and potentially dry–Age-Related Macular Degeneration (AMD). The current dogma is that lipofuscin’s cytotoxicity results from the light-triggered decomposition of its lipid-bisretinoids leading to apoptosis. However, antiapoptotic antioxidants or light-blocking lenses are not effective to stop degeneration in Stargardt and most AMD patients. Here, we show that lipofuscin forms aggregates in lysosomes, which trigger lysosomal membrane permeabilization and subsequent atypical necroptosis. We provide evidence that necrosulfonamide, necrostatin-7, and arimoclomol can effectively control this lethal cascade.
Stripping away ion hydration shells in electrical double-layer formation: Water networks matter
Authors: Alfarano Serena R. , Pezzotti Simone , Stein Christopher J. , Lin Zhou , Sebastiani Federico , Funke Sarah , Hoberg Claudius , Kolling Inga , Ma Chun Yu , Mauelshagen Katja , Ockelmann Thorsten , Schwaab Gerhard , Fu Li , Brubach Jean-Blaise , Roy Pascale , Head-Gordon Martin , Tschulik Kristina , Gaigeot Marie-Pierre , Havenith Martina
Published: November 2021

Significance

For centuries the double layer at the solid/electrolyte interface has been a central concept in electrochemistry. Today, it is still crucial for virtually all renewable energy storage and conversion technologies. Here, the double-layer formation is probed by THz spectroscopy with ultrabright synchrotron light as a source. Our results capture the molecular details of double-layer formation at positively/negatively charged Au electrodes for an NaCl electrolyte. We reveal a contrasting response applying positive versus negative bias, which is dictated by the interfacial water network and rationalized by accompanying molecular dynamics simulations and electronic-structure calculations. While Na
+
is directly attracted toward the negatively charged electrode, stripping of the Cl
−
hydration shell is observed only at larger potential values.
De novo germline mutation in the dual specificity phosphatase 10 gene accelerates autoimmune diabetes
Authors: Foray Anne-Perrine , Candon Sophie , Hildebrand Sara , Marquet Cindy , Valette Fabrice , Pecquet Coralie , Lemoine Sebastien , Langa-Vives Francina , Dumas Michael , Hu Peipei , Santamaria Pere , You Sylvaine , Lyon Stephen , Scott Lindsay , Bu Chun Hui , Wang Tao , Xu Darui , Moresco Eva Marie Y. , Scazzocchio Claudio , Bach Jean-François , Beutler Bruce , Chatenoud Lucienne
Published: November 2021

Significance

The vast majority of autoimmune diseases are polygenic, and causal loci uncovered by genetic-mapping studies explain only a minority of the heritable contribution to trait variation. Multiple explanations for this missing heritability include rare meaningful variants, rare copy number variations or deletions, epistasis, epigenetics, disease heterogeneity, and rare or infrequent variants that segregate within individual families (even within monozygotic twins). Here we demonstrate that experimental models of spontaneous autoimmune diseases may be invaluable tools to map rare germline variants impacting disease susceptibility traits. We identified a variant of the dual-specificity phosphatase 10 encoding gene that accelerates disease in an autoimmune type 1 diabetes model, the nonobese diabetic mouse.
Nanometer-resolution in situ structure of the SARS-CoV-2 postfusion spike protein
Authors: Tai Linhua , Zhu Guoliang , Yang Minnan , Cao Lei , Xing Xiaorui , Yin Guoliang , Chan Chun , Qin Chengfeng , Rao Zihe , Wang Xiangxi , Sun Fei , Zhu Yun
Published: November 2021

Significance

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a severe threat to public health and the global economy. Its spike protein is responsible for the membrane fusion and is thus a major target for vaccine and drug development. Our study presents the in situ structure of the spike protein in the postfusion state with higher resolution, giving further insights into the design of a viral entry inhibitor. Our observation of the oligomerization states of spikes on the viral membrane implies a possible mechanism of membrane fusion for viral infection.
The (minimal) persuasive advantage of political video over text
Authors: Wittenberg Chloe , Tappin Ben M. , Berinsky Adam J. , Rand David G.
Published: November 2021

Significance

Video is an increasingly common source of political information. Although conventional wisdom suggests that video is much more persuasive than other communication modalities such as text, this assumption has seldom been tested in the political domain. Across two large-scale randomized experiments, we find clear evidence that “seeing is believing”: individuals are more likely to believe an event took place when shown information in video versus textual form. When it comes to persuasion, however, the advantage of video over text is markedly less pronounced, with only small effects on attitudes and behavioral intentions. Together, these results challenge popular narratives about the unparalleled persuasiveness of political video versus text.
Multimodal on-chip nanoscopy and quantitative phase imaging reveals the nanoscale morphology of liver sinusoidal endothelial cells
Authors: Butola Ankit , Coucheron David A. , Szafranska Karolina , Ahmad Azeem , Mao Hong , Tinguely Jean-Claude , McCourt Peter , Senthilkumaran Paramasivam , Mehta Dalip Singh , Agarwal Krishna , Ahluwalia Balpreet Singh
Published: November 2021

Significance

We propose the integration of chip-based optical nanoscopy with high spatially sensitive quantitative phase microscopy to obtain three-dimensional (3D) morphology of liver sinusoidal endothelial cells (LSEC). LSEC contain large numbers of transcellular nanopores —“fenestrations”—in the plasma membrane, typically clustered in groups of 10 to 50 within areas called sieve plates. Determining the diameter and the height of fenestrated regions is an important indicator of a cell’s functionality, and these dimensions can be influenced by agents such as drugs. Our proposed multimodal microscope offers a solution for 3D nanoscale characterization of fenestration diameter and measurement of the optical thickness of the sieve plates.
An empirical resistance equation for the modelling of corona discharge in saline water
Authors: Stelmashuk Vitaliy , Schmidt Jiri
Published: November 2021

We present a study that was undertaken to calculate the resistance of low current corona discharge in saline water. A novel empirical model was obtained, based on several assumptions, which allowed us to determine the corona resistance using the measured current. This resistance could be then exploited to compute the power deposited to the corona as a function of time. The wall motion of a bubble freely oscillating in saline water was calculated using hydrodynamic equations and the calculated power function. A comparison of numerical simulations with experimental results showed that good agreement was achieved.
Anti-

APT

-symmetric Kerr gyroscope
Authors: Zhang Huilai , Peng Meiyu , Xu Xun-Wei , Jing Hui
Published: November 2021

Non-Hermitian systems can exhibit unconventional spectral singularities called exceptional points (EPs). Various EP sensors have been fabricated in recent years, showing strong spectral responses to external signals. Here we propose how to achieve a nonlinear anti-parity-time (

A
P
T

) gyroscope by spinning an optical resonator. We show that, in the absence of any nonlinearity, the sensitivity or optical mode splitting of the linear device can be magnified up to 3 orders compared to that of the conventional device without EPs. Remarkably, the

A
P
T

symmetry can be broken when including the Kerr nonlinearity of the materials and, as a result, the detection threshold can be significantly lowered, i.e., much weaker rotations which are well beyond the ability of a linear gyroscope can now be detected with the nonlinear device. Our work shows the powerful ability of

A
P
T

gyroscopes in practice to achieve ultrasensitive rotation measurement.
Photon number resolvability of multi-pixel superconducting nanowire single photon detectors using a single flux quantum circuit
Authors: Zhou Hou-Rong , Cheng Kun-Jie , Ren Jie , You Li-Xing , Ying Li-Liang , Yang Xiao-Yan , Li Hao , Wang Zhen
Published: November 2021

Superconducting nanowire single-photon detectors (SNSPDs) are typical switching devices capable of detecting single photons with almost 100% detection efficiency. However, they cannot determine the exact number of incident photons during a detection event. Multi-pixel SNSPDs employing multiple read-out channels can provide photon number resolvability (PNR), but they require increased cooling power and costly multi-channel electronic systems. In this work, a single-flux quantum (SFQ) circuit is employed, and PNR based on multi-pixel SNSPDs is successfully demonstrated. A multi-input magnetically coupled DC/SFQ converter (MMD2Q) circuit with a mutual inductance M is used to combine and record signals from a multi-pixel SNSPD device. The designed circuit is capable of discriminating the amplitude of the combined signals in accuracy of Φ
0/M with Φ
0 being a single magnetic flux quantum. By employing the MMD2Q circuit, the discrimination of up to 40 photons can be simulated. A 4-parallel-input MMD2Q circuit is fabricated, and a PNR of 3 is successfully demonstrated for an SNSPD array with one channel reserved for the functional verification. The results confirm that an MMD2Q circuit is an effective tool for implementing PNR with multi-pixel SNSPDs.