bluuebunny/crossref_metadata_2025 huggingface dataset:
Halogen bonding and rotational disorder in chlorine clathrate hydrate cages
Authors: Ochoa-Resendiz David , Gamboa-Suárez Antonio , Hernández-Lamoneda Ramón
Published: March 2022

We present a detailed theoretical characterization of the structure and interactions in dichlorine clathrate hydrate cages. In the case of the dodecahedral cage, there is clear evidence of the presence of halogen bonding, whereas in the tetrakaidecahedral cage, the expected signatures are there but in a weaker form. Comparison is made with the available structural data from x-ray experiments, where the rotational motion of dichlorine has been taken into account through Monte Carlo simulations illustrating delocalization effects associated with sampling multiple minima, specifically for the larger cage. Finally, the intermolecular potentials have been calculated with local correlation methods, and energy decomposition analysis has been applied to shed light on the nature of the interactions.
The effect of local thermal non-equilibrium on the onset of thermal instability for a metallic foam
Authors: Freitas Rômulo Bessi , Brandão Pedro Vayssière , Alves Leonardo Santos de Brito , Celli Michele , Barletta Antonio
Published: March 2022

Mixed convection in metallic foams modeled with Darcy's law under local thermal non-equilibrium conditions is investigated, where the solid phase thermal conductivity is assumed to be infinitely larger than its fluid phase counterpart. A linear and modal stability analysis was employed to evaluate the convective and absolute instability thresholds as well as their respective cell patterns. This analysis indicates that local thermal non-equilibrium always has a stabilizing effect and the spanwise uniform mode is always the most unstable. At the onset of convective instability, however, the number of equally unstable cell patterns increases with both the aspect ratio and the local thermal non-equilibrium strength.
Wading through the void: Exploring quantum friction and nonequilibrium fluctuations
Authors: Reiche D. , Intravaia F. , Busch K.
Published: March 2022

When two or more objects move relative to one another in vacuum, they experience a drag force, which, at zero temperature, usually goes under the name of quantum friction. This contactless non-conservative interaction is mediated by the fluctuations of the material-modified quantum electrodynamic vacuum and, hence, is purely quantum in nature. Numerous investigations have revealed the richness of the mechanisms at work, thereby stimulating novel theoretical and experimental approaches and identifying challenges and opportunities. In this Perspective, we provide an overview of the physics surrounding quantum friction and a perspective on recent developments.
Accumulation and alignment of elongated gyrotactic swimmers in turbulence
Authors: Liu Zehua , Jiang Linfeng , Sun Chao
Published: March 2022

We study the dynamics of gyrotactic swimmers in turbulence, whose orientation is governed by gravitational torque and local fluid velocity gradient. The gyrotaxis strength is measured by the ratio of the Kolmogorov time scale to the reorientation time scale due to gravity, and a large value of this ratio means the gyrotaxis is strong. By means of direct numerical simulations, we investigate the effects of swimming velocity and gyrotactic stability on spatial accumulation and alignment. Three-dimensional Voronoï analysis is used to study the spatial distribution and time evolution of the particle concentration. We study spatial distribution by examining the overall preferential sampling, where clusters and voids (subsets of particles that have small and large Voronoï volumes, respectively) form. Compared with the ensemble particles, the preferential sampling of clusters and voids is found to be more pronounced. The clustering of fast swimmers lasts much longer than slower swimmers when the gyrotaxis is strong and intermediate, but an opposite trend emerges when the gyrotaxis is weak. In addition, we study the preferential alignment with the Lagrangian stretching direction, with which passive slender rods have been known to align. We show that the Lagrangian alignment is reduced by the swimming velocity when the gyrotaxis is weak, while the Lagrangian alignment is enhanced for the regime in which gyrotaxis is strong.
Effects of the Coriolis force in inhomogeneous rotating turbulence
Authors: Hu Running , Li Xinliang , Yu Changping
Published: March 2022

The effects of the Coriolis force in inhomogeneous rotating turbulence are studied in the paper. Linear analyses and numerical simulations both reveal that energy is transported to the slowly rotating fields, and the energy distribution is proportional to Ω3−2(x3). The scale energy is almost spatially self-similar, and the inverse cascade is reduced by inhomogeneous rotation. The corresponding evolution equation of the scale energy, i.e., the generalized Kolmogorov equation, is calculated to study the scale transport process in the presence of inhomogeneity. The equation is reduced to twice the energy transport equation at sufficiently large scales, which is verified by numerical results. In addition, the results reveal the dominant role of the corresponding pressure of the Coriolis force in the spatial energy transport. An extra turbulent convention effect in r-space solely in slowly rotating fields is also recognized. It can be associated with the small-scale structures with strong negative vorticity, whose formation mechanism is similar to rotating condensates. Finally, by vortex dynamic analyses, we find that the corresponding pressure of the Coriolis force transports energy by vorticity tube shrinking and thickening. The effects of the Coriolis force can be divided into two components: one is related to the gradient of rotation, and the other is associated with the strength of rotation.
On the initiation and evolution of dielectric breakdown in auto-magnetizing liner experiments
Authors: Shipley G. A. , Awe T. J. , Hutsel B. T. , Yager-Elorriaga D. A.
Published: March 2022

Auto-magnetizing (AutoMag) liners are cylindrical tubes composed of discrete metallic helices encapsulated in insulating material; when driven with a ∼2 MA, ∼100-ns prepulse on the 20 MA, 100-ns rise time Z accelerator, AutoMag targets produced >150 T internal axial magnetic fields [Shipley et al., Phys. Plasmas 26, 052705 (2019)]. Once the current rise rate of the pulsed power driver reaches sufficient magnitude, the induced electric fields in the liner cause dielectric breakdown of the insulator material and, with sufficient current, the cylindrical target radially implodes. The dielectric breakdown process of the insulating material in AutoMag liners has been studied in experiments on the 500–900 kA, ∼100-ns rise time Mykonos accelerator. Multi-frame gated imaging enabled the first time-resolved observations of photoemission from dynamically evolving plasma distributions during the breakdown process in AutoMag targets. Using magnetohydrodynamic simulations, we calculate the induced electric field distribution and provide a detailed comparison to the experimental data. We find that breakdown in AutoMag targets does not primarily depend on the induced electric field in the gaps between conductive helices as previously thought. Finally, to better control the dielectric breakdown time, a 12–32 mJ, 170 ps ultraviolet (λ = 266 nm) laser was implemented to irradiate the outer surface of AutoMag targets to promote breakdown in a controlled manner at a lower internal axial field. The laser had an observable effect on the time of breakdown and subsequent plasma evolution, indicating that pulsed UV lasers can be used to control breakdown timing in AutoMag.
Morpho-dynamic evolution due to inertia-mediated impact of a compound drop on a deep liquid pool
Authors: Boruah Manash Protim , Randive Pitambar R. , Pati Sukumar , Chakraborty Suman
Published: March 2022

A compound drop impacting on a liquid pool exhibits intriguing coalescence patterns that are primarily attributable to the complicated interplay of inertia with other physical parameters such as radius ratio of core to shell drop and density and viscosity contrasts of the two fluids. By executing comprehensive numerical investigations, here, we identify three different regimes based on the radius ratio of compound drop, viz., secondary drop pinch-off without bubble bursting, secondary drop pinch-off after bubble bursting, and compound breakage. Our findings also depict a transition in the shape of a secondary droplet from prolate to oblate or vice versa, a phenomenon non-trivially culminated by secondary drop pinch-off timing, neck radius, and amplitude and wavelength of capillary wave propagation. Our results bring out the fact that higher wavelength and amplitude of capillary waves are responsible for secondary drop pinch-off without bubble bursting. Furthermore, in the case of highly viscous core drop and surrounding fluid, we observe both complete and partial coalescence phenomena, which are critically dictated by the confluence of inertia and radius ratio of a compound drop leading to three different regimes, viz., complete coalescence without bubble bursting, complete coalescence with bubble bursting, and partial coalescence with bubble bursting, distinctively different from the observations for single droplet based investigations reported in earlier studies. These implications are likely to be beneficial in illustrating the physical functionalities accompanying the targeted release of encapsulated biological or pathological entities when they are transmitted under the action of an inertial force into another fluidic medium, a paradigm that has hitherto remained unexplored.
Social disadvantage, economic inequality, and life expectancy in nine Indian states
Authors: Vyas Sangita , Hathi Payal , Gupta Aashish
Published: March 2022

Significance

India is one of the most hierarchical societies in the world. Because vital statistics are incomplete, mortality disparities are not quantified. Using survey data on more than 20 million individuals from nine Indian states representing about half of India’s population, we estimate and decompose life expectancy differences between higher-caste Hindus, comprising other backward classes and high castes, and three marginalized social groups: Adivasis (indigenous peoples), Dalits (oppressed castes), and Muslims. The three marginalized groups experience large disadvantages in life expectancy at birth relative to higher-caste Hindus. Economic status explains less than half of these gaps. These large disparities underscore parallels between diverse systems of discrimination akin to racism. They highlight the global significance of addressing social inequality in India.
Rapid recruitment of p53 to DNA damage sites directs DNA repair choice and integrity
Authors: Wang Yu-Hsiu , Ho Teresa L. F. , Hariharan Anushya , Goh Hui Chin , Wong Yao Liang , Verkaik Nicole S. , Lee May Yin , Tam Wai Leong , van Gent Dik C. , Venkitaraman Ashok R. , Sheetz Michael P. , Lane David P.
Published: March 2022

Significance

Our work focuses on the critical longstanding question of the nontranscriptional role of p53 in tumor suppression. We demonstrate here that poly(ADP-ribose) polymerase (PARP)–dependent modification of p53 enables rapid recruitment of p53 to damage sites, where it in turn directs early repair pathway selection. Specifically, p53-mediated recruitment of 53BP1 at early time points promotes nonhomologous end joining over the more error-prone microhomology end-joining. Similarly, p53 directs nucleotide excision repair by mediating DDB1 recruitment. This property of p53 also correlates with tumor suppression in vivo. Our study provides mechanistic insight into how certain transcriptionally deficient p53 mutants may retain tumor-suppressive functions through regulating the DNA damage response.
CO
2
fertilization of terrestrial photosynthesis inferred from site to global scales
Authors: Chen Chi , Riley William J. , Prentice I. Colin , Keenan Trevor F.
Published: March 2022

Significance

The magnitude of the CO
2
fertilization effect on terrestrial photosynthesis is uncertain because it is not directly observed and is subject to confounding effects of climatic variability. We apply three well-established eco-evolutionary optimality theories of gas exchange and photosynthesis, constraining the main processes of CO
2
fertilization using measurable variables. Using this framework, we provide robust observationally inferred evidence that a strong CO
2
fertilization effect is detectable in globally distributed eddy covariance networks. Applying our method to upscale photosynthesis globally, we find that the magnitude of the CO
2
fertilization effect is comparable to its in situ counterpart but highlight the potential for substantial underestimation of this effect in tropical forests for many reflectance-based satellite photosynthesis products.
Auxin methylation by
IAMT1
, duplicated in the legume lineage, promotes root nodule development in
Lotus japonicus
Authors: Goto Takashi , Soyano Takashi , Liu Meng , Mori Tomoko , Kawaguchi Masayoshi
Published: March 2022

Significance

IAA carboxyl methyltransferase 1 (IAMT1) converts auxin (IAA) into its methyl ester (MeIAA).
IAMT1
is reportedly critical for shoot development of the nonsymbiotic plant
Arabidopsis
. On the other hand, the function of
IAMT1
in roots is unknown. Here, we found that
IAMT1
is duplicated in the legume lineage, which evolved root nodule symbiosis. In the model legume
Lotus japonicus
, one of two paralogs (named
IAMT1a
) was mainly expressed in root epidermis, but its function is required in the adjacent cell layer, root cortex, where it promotes nodule development. Application of MeIAA, but not IAA, significantly induced
NIN
, a master regulator of nodule development, without rhizobia. These findings illuminate our understanding of intertissue communication acquired during evolution of root nodule symbiosis.
Antibody cross-reactivity between casein and myelin-associated glycoprotein results in central nervous system demyelination
Authors: Chunder Rittika , Weier Alicia , Mäurer Hannah , Luber Nicolas , Enders Michael , Luber Gabriele , Heider Thorsten , Spitzer Alfred , Tacke Sabine , Becker-Gotot Janine , Kurts Christian , Iyer Radhika , Ho Peggy P. , Robinson William H. , Lanz Tobias V. , Kuerten Stefanie
Published: March 2022

Significance

Multiple sclerosis (MS) is the most prevalent autoimmune disease of the central nervous system (CNS), leading to irreversible deficits in young adults. Its pathophysiology is believed to be influenced by environmental determinants. As far back as the 1990s, it had been suggested that there is a correlation between the consumption of cow’s milk and the prevalence of MS. Here, we not only demonstrate that a high percentage of MS patients harbor antibodies to bovine casein but also that antibody cross-reactivity between cow’s milk and CNS antigens can exacerbate demyelination. Our data broaden the current understanding of how diet influences the etiology of MS and set the stage for combining personalized diet plans with disease-modifying treatment strategies.
Eukaryotic catecholamine hormones influence the chemotactic control of
Vibrio campbellii
by binding to the coupling protein CheW
Authors: Weigert Muñoz Angela , Hoyer Elisabeth , Schumacher Kilian , Grognot Marianne , Taute Katja M. , Hacker Stephan M. , Sieber Stephan A. , Jung Kirsten
Published: March 2022

Significance

Host-emitted stress hormones significantly influence the growth and behavior of various bacterial species; however, their cellular targets have so far remained elusive. Here, we used customized probes and quantitative proteomics to identify the target of epinephrine and the α-adrenoceptor agonist phenylephrine in live cells of the aquatic pathogen
Vibrio campbellii
. Consequently, we have discovered the coupling protein CheW, which is in the center of the chemotaxis signaling network, as a target of both molecules. We not only demonstrate direct ligand binding to CheW but also elucidate how this affects chemotactic control. These findings are pivotal for further research on hormone-specific effects on bacterial behavior.
CD164 is a host factor for lymphocytic choriomeningitis virus entry
Authors: Bakkers Mark J. G. , Moon-Walker Alex , Herlo Rasmus , Brusic Vesna , Stubbs Sarah Hulsey , Hastie Kathryn M. , Saphire Erica Ollmann , Kirchhausen Tomas L. , Whelan Sean P. J.
Published: March 2022

Significance

Lymphocytic choriomeningitis virus (LCMV) is the prototypic arenavirus and has been utilized for decades as a model to understand the host immune response against viral infection. LCMV infection can lead to fatal meningitis in immunocompromised people and can lead to congenital birth defects and spontaneous abortion if acquired during pregnancy. Using a genetic screen, we uncover host factors involved in LCMV entry that were previously unknown and are candidate therapeutic targets to combat LCMV infection. This study expands our understanding of the entry pathway of LCMV, revealing that its glycoprotein switches from utilizing the known receptor α-DG and heparan sulfate at the plasma membrane to binding the lysosomal mucin CD164 at pH levels found in endolysosomal compartments, facilitating membrane fusion.
Structures of the junctophilin/voltage-gated calcium channel interface reveal hot spot for cardiomyopathy mutations
Authors: Yang Zheng Fang , Panwar Pankaj , McFarlane Ciaran R. , Tuinte Wietske E. , Campiglio Marta , Van Petegem Filip
Published: March 2022

Significance

Ion channels have evolved the ability to communicate with one another, either through protein–protein interactions, or indirectly via intermediate diffusible messenger molecules. In special cases, the channels are part of different membranes. In muscle tissue, the T-tubule membrane is in proximity to the sarcoplasmic reticulum, allowing communication between L-type calcium channels and ryanodine receptors. This process is critical for excitation–contraction coupling and requires auxiliary proteins like junctophilin (JPH). JPHs are targets for disease-associated mutations, most notably hypertrophic cardiomyopathy mutations in the JPH2 isoform. Here we provide high-resolution snapshots of JPH, both alone and in complex with a calcium channel peptide, and show how this interaction is targeted by cardiomyopathy mutations.
Digital synthesis of free-form multimaterial structures for realization of arbitrary programmed mechanical responses
Authors: Li Weichen , Wang Fengwen , Sigmund Ole , Zhang Xiaojia Shelly
Published: March 2022

Significance

Creating structures to realize function-oriented mechanical responses is desired for many applications. Yet, the use of a single material phase and heuristics-based designs may fail to attain specific target behaviors. Here, through a deterministic algorithmic procedure, multiple materials with dissimilar properties are intelligently synthesized into composite structures to achieve arbitrary prescribed responses. Created structures possess unconventional geometry and seamless integration of multiple materials. Despite geometric complexity and varied material phases, these structures are fabricated by multimaterial manufacturing, and tested to demonstrate that wide-ranging nonlinear responses are physically and accurately realized. Upon heteroassembly, resulting structures provide architectures that exhibit highly complex yet navigable responses. The proposed strategy can benefit the design of function-oriented nonlinear mechanical devices, such as actuators and energy absorbers.
Deep learning guided optimization of human antibody against SARS-CoV-2 variants with broad neutralization
Authors: Shan Sisi , Luo Shitong , Yang Ziqing , Hong Junxian , Su Yufeng , Ding Fan , Fu Lili , Li Chenyu , Chen Peng , Ma Jianzhu , Shi Xuanling , Zhang Qi , Berger Bonnie , Zhang Linqi , Peng Jian
Published: March 2022

Significance

SARS-CoV-2 continues to evolve through emerging variants, more frequently observed with higher transmissibility. Despite the wide application of vaccines and antibodies, the selection pressure on the Spike protein may lead to further evolution of variants that include mutations that can evade immune response. To catch up with the virus’s evolution, we introduced a deep learning approach to redesign the complementarity-determining regions (CDRs) to target multiple virus variants and obtained an antibody that broadly neutralizes SARS-CoV-2 variants.
Sister chromatids separate during anaphase in a three-stage program as directed by interaxis bridges
Authors: Chu Lingluo , Zhang Zheng , Mukhina Maria , Zickler Denise , Kleckner Nancy
Published: March 2022

Significance

A central feature of mitosis is segregation of sister chromatids to opposite poles during anaphase. Our recent work revealed that sister chromatids are linked by robust structural bridges built on topological sister/sister catenations. This unexpected finding implies that separation of sister chromatids is more complex than previously thought. The present study reveals that bridges are removed in a highly programmed three-stage process, all licensed by anaphase onset and cohesin removal, and all promoted by distinct types of intersister separation forces. Removal of bridge-associated cohesin and topoisomerase II–mediated decatenation plays a central role. These findings raise the possibility that the presence and programmed removal of bridges are required for smooth, synchronous, and regular movement of sisters to opposite poles.
Disruption of the circadian clock component BMAL1 elicits an endocrine adaption impacting on insulin sensitivity and liver disease
Authors: Jouffe Céline , Weger Benjamin D. , Martin Eva , Atger Florian , Weger Meltem , Gobet Cédric , Ramnath Divya , Charpagne Aline , Morin-Rivron Delphine , Powell Elizabeth E. , Sweet Matthew J. , Masoodi Mojgan , Uhlenhaut N. Henriette , Gachon Frédéric
Published: March 2022

Significance

While increasing evidence associates the disruption of circadian rhythms with pathologic conditions, including obesity, type 2 diabetes, and nonalcoholic fatty liver diseases (NAFLD), the involved mechanisms are still poorly described. Here, we show that, in both humans and mice, the pathogenesis of NAFLD is associated with the disruption of the circadian clock combined with perturbations of the growth hormone and sex hormone pathways. However, while this condition protects mice from the development of fibrosis and insulin resistance, it correlates with increased fibrosis in humans. This suggests that the perturbation of the circadian clock and its associated disruption of the growth hormone and sex hormone pathways are critical for the pathogenesis of metabolic and liver diseases.
Seismic noise effect reduction improvement for ground-based investigation of space inertial sensor by suspending the electrode housing with an individual pendulum
Authors: Tan D Y , Liu L , Hu M , Zhou Z B
Published: March 2022

Seismic noise is one of the main limits of performance validation experiments for space inertial sensor on the ground. A two-stage electrostatically controlled torsion pendulum was developed and used to investigate the performances of space inertial sensor for TianQin. To further suppress the seismic noise effect, a novel scheme that introduces another pendulum to suspend the electrode housing (EH) simultaneously is proposed. By choosing proper suspension for the EH with respect to the original pendulum for the test mass (TM), the relative motion between the TM and the EH is insensitive to seismic noise due to common mode rejection, and the disturbance on the inertial sensor caused by seismic noise can be suppressed about five orders of magnitude theoretically. Both theoretical analysis and experimental results show that the scheme can further suppress the seismic noise effect more than one order of magnitude.
A toy model for gas viscosity
Authors: Sapia P , Bozzo G
Published: March 2022

We present a greatly simplified model (a ‘toy model’) for the rheological behavior of gases in laminar motion, whose viscosity arises mainly from thermal diffusion of momentum among layers. The model is based on the usual mesoscopic representation of a fluid in laminar motion (i.e. many layers reciprocally sliding on each other), where the mechanical coupling among layers is modeled by means of mass exchange, that in turns results in momentum diffusion transversally to the fluid flow. In particular, the model is based on the conceptual analogy between: a laminarly flowing fluid, on one side, and, on the other side, an arbitrary number of identical trains sliding on parallel rails, reciprocally interacting through mass exchange between nearest neighbors. Before presenting the complete model, a simplest case is considered, in order to familiarize learners with the idea that mass exchange between two mechanical systems can give rise to an emerging interaction force between them. The proposed model, appropriate for university students (and, limited to the simplest case, for upper high school students, too), helps them to understand the basic idea of viscosity as a transport phenomenon, giving the opportunity to better understand—in a unitary way—the physics underlying various transport phenomena, such as: electric conduction, heat conduction, diffusion. Moreover, the computational implementation of the model is done by using a mathematical formalism, which in turns permits students to familiarize (in a classical physics context) with the matrix notation and the physical meaning of matrix elements, to the benefit of their subsequent quantum mechanics studies.
Image irradiance in the absence of aplanatism and isoplanatism
Authors: Siew Ronian
Published: March 2022

Textbook chapters on the subject of optical radiometry often impose the condition of aplanatism when deriving a well-known expression for image irradiance in optical systems, yet at least two authors (including this author) have shown that this condition is unnecessary for the expression to hold. In this paper, theories and computer-aided ray-tracing analyses are provided to support the validity of the expression for even wider cases, where stigmatism, aplanatism, and isoplanatism are all not assumed. Further, it is shown that when both diffraction and aberrations are involved, one may apply a fusion of the expression with the fundamentals of image formation by convolution (if the image is isoplanatic) or superposition (if the image is not isoplanatic) in Fourier optics. To highlight how graduate students and researchers in the laboratory may benefit from the concepts presented here, a practical application is discussed involving signal detection.
Shearlet-based regularization in statistical inverse learning with an application to x-ray tomography
Authors: Bubba Tatiana A , Ratti Luca
Published: March 2022

Statistical inverse learning theory, a field that lies at the intersection of inverse problems and statistical learning, has lately gained more and more attention. In an effort to steer this interplay more towards the variational regularization framework, convergence rates have recently been proved for a class of convex, p-homogeneous regularizers with p ∈ (1, 2], in the symmetric Bregman distance. Following this path, we take a further step towards the study of sparsity-promoting regularization and extend the aforementioned convergence rates to work with ℓ

p
-norm regularization, with p ∈ (1, 2), for a special class of non-tight Banach frames, called shearlets, and possibly constrained to some convex set. The p = 1 case is approached as the limit case (1, 2) ∋ p → 1, by complementing numerical evidence with a (partial) theoretical analysis, based on arguments from Γ-convergence theory. We numerically validate our theoretical results in the context of x-ray tomography, under random sampling of the imaging angles, using both simulated and measured data. This application allows to effectively verify the theoretical decay, in addition to providing a motivation for the extension to shearlet-based regularization.
Resonance signatures in DCS and spin polarization for positron scattering with C60 and rare gas endohedrals
Authors: Dubey Km Akanksha , Ciappina Marcelo F
Published: March 2022

We present a comparative study of differential cross sections (DCSs) and spin polarizations for positron scattering from C60 and A@C60, elucidating the role of encapsulation of rare gas atoms inside the giant C60 cage. A comparison is provided with the earlier work for elastic positron-C60 scattering. We find a very good agreement even when a model potential is used for the positron-C60 interaction. Also, we evaluate similarities and differences between the positron and electron DCSs and spin polarizations, both from bare and endohedral targets. To mark resonance features on the scattering dynamics, DCSs and spin polarizations are calculated at resonant energies, which showcase different characteristics compared to the cases where the positron energy is non-resonant. In order to account for a complete picture of the scattering process, an absorption potential is included in the total scattering field. For the sake of illustrating the impact of individual interactions and their interplay as a whole, DCSs and spin polarizations are reported including several scattering interactions alternatively.
An inventive multi-scale, multiphysics modeling approach and comparative analysis of distinctive features of planar ionization waves in air: I. Negative streamers
Authors: Shahsavarian Tohid , Cao Yang
Published: March 2022

A multiscale-multiphysics model of two different patterns of negative discharge (droplets and branches) based on the well-known electro-hydrodynamic equations in a two-dimensional non-axisymmetric configuration is developed to investigate the main features of the negative discharge (e.g. bifurcation, stochastic branching, and evolution of all charged particles including positive and negative ions and electrons). We discuss the challenges behind the finite-element-based streamer models and illustrate the robustness and efficiency of introduced three different meshing techniques via coupled fixed and adaptively refined meshes in terms of the accuracy of results and computational burden. The capability of the model in representing an outstanding spatial resolution of the streamer propagation and its stages is demonstrated under both uniform and non-uniform electric fields. A further required extension of the presented model for the representation of the positive streamer is presented in part II of this series paper. Also, in this part, the distinctive characteristics of both positive and negative streamers are presented, and the different features achieved from the model are thoroughly discussed and compared with the prior experimental results.
An inventive multi-scale, multiphysics modelling approach and comparative analysis of distinctive features of planar ionization waves in air: II. Positive streamers
Authors: Shahsavarian Tohid , Cao Yang
Published: March 2022

A robust numerical framework for positive streamer modelling based on electro-hydrodynamic equations coupled with Poisson and Helmholtz differential equations for the photoionization process is presented. The proposed multi-layer meshing scheme in a 2D non-axisymmetric finite-element model along with a hybrid meshing technique presented in part I of this series paper for negative streamers provide high accuracy, spatial resolution, and capability to present the major features of both positive and negative streamers. In addition, the presented model is utilized to simulate multi positive and negative streamers propagation in a non-uniform electric field in the air. The main characteristics of the positive and negative streamers including the morphology, distribution pattern of space charges, local electric field, diameter, length, and velocity are presented, discussed, and compared with the experiment. Moreover, the impacts of initial seed density and voltage on the propagation of streamers are presented and explained. The branching mechanism arising from Laplacian instability and its impact on the streamer parameters such as tip electric field and dominant charge density is explained.
Characteristics of three-electrode pulsed surface dielectric barrier discharge: streamer-to-spark transition and hydrodynamic expansion
Authors: Peng Bangfa , Jiang Nan , Shang Kefeng , Lu Na , Li Jie , Wu Yan
Published: March 2022

Streamer-to-spark transition and hydrodynamic expansion in a three-electrode pulsed surface dielectric barrier discharge are studied under atmospheric-pressure air. Three sequential discharge processes of the primary streamer, transitional streamer and spark phase during a single pulse are observed from the time-resolved plasma morphologies. The primary streamer and transitional streamer phases, with a rising voltage and low current, followed by a spark phase with a rapidly falling pulse and ascending current are characterized. Images of the discharge development show that the transitional streamer is maintained in the ionization channel after the primary streamer bridges the high-voltage electrode and the second grounded electrode. When the transitional streamer develops to a certain level, the streamer discharge transfers into the spark discharge. As a result, two shock waves are induced in the two exposed electrode domains, and then merge into a single ellipse during the process of hydrodynamic expansion. Boltzmann plots indicate that the electron temperature is 4.815 eV in the initial phase of spark discharge and gradually decreases in the spark phase. Stark broadening of the O atomic line shows that the electron density is 7.06 × 1017 cm−3 during the spark phase.
Simplified Green’s function for surface waves in quasi-incompressible elastic plates with application to elastography
Authors: Benech Nicolás , Camargo Andrés , Negreira Carlos
Published: March 2022

Surface wave elastography is a growing method to estimate the elasticity in soft solids. It is particularly useful in the case of agrifoods like meat, cheese, or fruits because it does not require major infrastructure or large equipment and could be developed in portable devices. However, estimating the shear elastic properties from surface wave measurements is not straightforward. The shear wavelength in those materials is cm sized for the excitation frequencies usually employed in elastography (∼102 Hz), and the size of samples is comparable to it. Thus, the surface wave speed is frequency dependent with no direct relation to the shear wave speed. In this work we propose a simplified Green’s function for soft solid elastic plates which allows to retrieve the shear elasticity from near field measurements. The model is compared with experimental results obtained in agar–gelatin phantoms and food samples (cheese and bovine liver). The results show a good overall agreement although improvements can be achieved by incorporating diffraction and viscosity to the model.
Periodic error detection and separation of magnetic levitation gyroscope signals based on continuous wavelet transform and singular spectrum analysis
Authors: Wang Yiwen , Yang Zhiqiang , Shi Zhen , Ma Ji , Liu Di , Shi Ling
Published: March 2022

The accuracy of the north azimuth measured using the magnetic levitation gyroscope (GAT) declines owing to the influence of the periodic errors of GAT signals induced by the systematic error of the gyro rotor system and the influence of external environment. To address this issue, this paper proposes a novel methodological strategy based on continuous wavelet transform (CWT) and singular spectrum analysis (SSA) to process GAT periodic errors and improve the accuracy of north-seeking. Firstly, CWT is used to process a large number of GAT signals to obtain the statistical characteristics of the periodic errors. Subsequently, the reconstructed components (RCs) of the GAT signals are obtained using SSA. After detecting and grouping the periodic terms contained in each RC using CWT, the periodic errors in the GAT signals are clearly separated. Finally, the effectiveness of this method was verified by comparing our north azimuths with those measured using the high-precision global navigation satellite system (GNSS) baseline. Our results indicated that the periodic errors in GAT signals can be accurately divided into the high frequency periodic error and the low frequency periodic error, and both periodic errors can be clearly detected and separated. After processing, the root mean square error of the GAT rotor currents and the absolute difference between the gyro and high-precision GNSS north azimuths were enhanced by 22.6% and 43.2%, respectively. The method presented in this paper to process periodic errors is suitable for use in the preprocessing of GAT signals.
A novel dynamic method for the storage of calibration gas mixtures based on thermal mass flow controllers
Authors: Loianno Valerio , Mensitieri Giuseppe
Published: March 2022

A dynamic method for the storage of calibration gas mixtures is presented using thermal mass flow controllers (MFCs) connected to a dead end volume. The approach relies on barometry to calibrate the unknown constant volume and two MFCs which regulate the flow rate of carbon dioxide and methane respectively. Binary gas mixtures of these components are prepared and stored within the calibrated volume tank up to 9 bar at ambient temperature. Thermodynamic data of pressure, temperature and density of the gas mixtures are retrieved. The expanded uncertainties at 95% confidence level of the molar fraction and the density of the mixture are evaluated. FTIR Spectroscopy is used in situ to analyse the gas mixtures.
The microwave properties of tin sulfide thin films prepared by RF magnetron sputtering techniques
Authors: Dragoman Mircea , Aldrigo Martino , Dinescu Adrian , Iordanescu Sergiu , Romanitan Cosmin , Vulpe Silviu , Dragoman Daniela , Braniste Tudor , Suman Victor , Rusu Emil , Tiginyanu Ion
Published: March 2022

In this paper we present the microwave properties of tin sulfide (SnS) thin films with the thickness of just 10 nm, grown by RF magnetron sputtering techniques on a 4 inch silicon dioxide/high-resistivity silicon wafer. In this respect, interdigitated capacitors in coplanar waveguide technology were fabricated directly on the SnS film to be used as both phase shifters and detectors, depending on the ferroelectric or semiconductor behaviour of the SnS material. The ferroelectricity of the semiconducting thin layer manifests itself in a strong dependence of the electrical permittivity on the applied DC bias voltage, which induces a phase shift of 30 degrees mm−1 at 1 GHz and of 8 degrees mm−1 at 10 GHz, whereas the transmission losses are less than 2 dB in the frequency range 2–20 GHz. We have also investigated the microwave detection properties of SnS, obtaining at 1 GHz a voltage responsivity of about 30 mV mW−1 in the unbiased case and with an input power level of only 16 μW.
Temperature-dependent resistance of carbon nanotube fibers
Authors: Song Yanhui , Di Jiangtao , Jia Yinlei , Yong Zhengzhong , Xu Jifeng
Published: March 2022

Carbon nanotube fibers are highly recommended in the field of temperature sensor application owing to their excellent electrical conductivity and thermal conductivity. Here, this work demonstrated the rapid thermal response behaviour of CNT fibers fabricated by floating catalyst CVD method, which was measured by an in situ technique based on the CNT film electric heater with excellent electrothermal response properties. The temperature dependences of resistance and structure were both explored. Experimental investigation indicates that the reduction in the inter-CNT interspace in the fibers caused by thermally driven actuation was dominantly responsible for the decrease of the fibers resistance during the heating process. Especially, the heated fibers showed 7.2% decrease in electrical resistance at the applied square-wave voltage of 8 V, and good temperature sensitivity (−0.15% °C−1). The as-prepared CNT fibers also featured a rapid and reversible electrical resistance response behaviour when exposed to external heating stimulation. Additionally, with the increment of temperature and twist-degree, the generated contraction actuation increased, which endowed the CNT fibers with more decrease in electrical resistance. These observations further suggested that the temperature-dependent conduction behavior of the CNT fibers with a high reversibility and repeatability was strongly correlated with their structure response to heat stimulation. As a consequence, the temperature-conduction behavior described here may be applied in other CNT-structured fibers and facilitated the improvement in their temperature-sensing applications.
MAPbBr3 nanocrystals from aqueous solution for poly(methyl methacrylate)-MAPbBr3 nanocrystal films with compression-resistant photoluminescence
Authors: Tang Xiaobing , Zhang Yulin , Kothalawala Nadeesha Lakmali , Wen Xiyu , Kim Doo Young , Yang Fuqian
Published: March 2022

In this work, we develop an environmental-friendly approach to produce organic-inorganic hybrid MAPbBr3 (MA = CH3NH3) perovskite nanocrystals (PeNCs) and PMMA-MAPbBr3 NC films with excellent compression-resistant PL characteristics. Deionized water is used as the solvent to synthesize MAPbBr3 powder instead of conventionally-used hazardous organic solvents. The MAPbBr3 PeNCs derived from the MAPbBr3 powder exhibit a high photoluminescence quantum yield (PLQY) of 93.86%. Poly(methyl methacrylate) (PMMA)-MAPbBr3 NC films made from the MAPbBr3 PeNCs retain ∼97% and ∼91% of initial PL intensity after 720 h aging in ambient environment at 50 °C and 70 °C, respectively. The PMMA-MAPbBr3 NC films also exhibit compression-resistant photoluminescent characteristics in contrast to the PMMA-CsPbBr3 NC films under a compressive stress of 1.6 MPa. The PMMA-MAPbBr3 NC film integrated with a red emissive film and a blue light emitting source achieves an LCD backlight of ∼114% color gamut of National Television System Committee (NTSC) 1953 standard.
Impact and workload are dominating on-field data monitoring techniques to track health and well-being of team-sports athletes
Authors: Cheng Runbei , H M Bergmann Jeroen
Published: March 2022

Objective. Participation in sports has become an essential part of healthy living in today’s world. However, injuries can often occur during sports participation. With advancements in sensor technology and data analytics, many sports have turned to technology-aided, data-driven, on-field monitoring techniques to help prevent injuries and plan better player management. Approach. This review searched three databases, Web of Science, IEEE, and PubMed, for peer-reviewed articles on on-field data monitoring techniques that are aimed at improving the health and well-being of team-sports athletes. Main results. It was found that most on-field data monitoring methods can be categorized as either player workload tracking or physical impact monitoring. Many studies covered during this review attempted to establish correlations between captured physical and physiological data, as well as injury risk. In these studies, workloads are frequently tracked to optimize training and prevent overtraining in addition to overuse injuries, while impacts are most often tracked to detect and investigate traumatic injuries. Significance. This review found that current sports monitoring practices often suffer from a lack of standard metrics and definitions. Furthermore, existing data-analysis models are created on data that are limited in both size and diversity. These issues need to be addressed to create ecologically valid approaches in the future.
A variable reluctance based rotational electromagnetic harvester for the high-speed smart bearing
Authors: Gong Yun , Wang Sijia , Xie Zhengqiu , Zhang Tao , Chen Zhiwen , Lin Wanrong , Huang Wenbin
Published: March 2022

In recent years, smart bearing technology is being developed for the purpose of prolonging the reliability and the service time of bearing by detecting the early faults and regulating the working condition. However, powering wireless monitoring devices integrated within the smart bearing is still an uphill task due to the limited power capacity and lifetime of traditional power cells. In this paper, a variable reluctance energy harvester (VREH) is proposed to scavenge the rotating energy from the bearing, which includes a toothed spacer and an m-shape electric steel with a coil and a permanent magnet on each leg. The key parameters of the proposed harvester are analyzed and discussed via the theoretical study and the finite element analysis. In comparison with the VREH without the middle magnet, the proposed harvester greatly improves the energy harvesting performance and reduces the magnetic flux leakage to the ferromagnetic environment. Simulation results show that for the air and ferromagnetic environments, the average output power improvement of the VREH with the middle magnet reaches 33.89% and 61.6%, respectively. A fabricated prototype is tested using the high-speed railway bearing testing machine. The influence of the impedance matching circuit and the coil connection on the VREH is investigated with the rotating speed varying from 600 r min−1 to 1800 r min−1. An energy management and storage circuit is designed and fabricated to test the energy conversion performance of the proposed harvester. Under the impedance matched condition, the optimal root mean square (RMS) output power is of 72.13–414.86 mW. It is shown that the proposed electromagnetic harvester is capable of collecting the rotational energy in the ferromagnetic environment and can be used for the high-speed smart bearing applications.
Josephson junctions with chiral p-wave ferromagnetic superconductor reservoirs in presence of spin-orbit coupling interaction
Authors: Shomali Zahra
Published: March 2022

The spin transfer torque (STT), is studied in new cases of Josephson junctions containing triplet p-wave chiral ferromagnetic superconductor (FS) reservoirs. To be more precise, FS1|spin orbit coupling layer (SOC1)|Normal metal (N)|SOC2|FS2 materials have been investigated. Specifically, FS1|N|FS2 structure with one layer of SOC at FS1|N interface and also two layers of SOC at both FS1|N and N|FS2 interfaces are investigated. For the structures including two SOC layers, both symmetric and asymmetric cases with respectively equal and different potential strengths are studied. The ballistic Josephson junctions are studied solving the Bogoliubov–de-Gennes equation. In particular, the cases with short normal metal contacts with thickness much smaller than the superconducting coherence length, ψ, are studied. It is obtained for the case with only one SOC layer, while the absolute value of the out-of-plane STT remains almost unchanged, its direction reverses for lower values of α, the angle between exchange fields of the two FSs. Also, the nanosystem in presence of two similar SOCs, exhibits lower out-of-plane STT. This is justified as the unit vector along the interface normal for the SOC1 is in the opposite direction of the second SOC2 layer. Hence, one can expect that these potentials fade the effect of each other. When the SOCs are not the same and have different values of potential strength, the out-of-plane STT reduces less which is attributed to slighter cancellation due to unequal potential strength. Moreover, the barrier strength is varied. It has been shown that the barrier strength increment changes the behavior of the STT. Particularly, it is found that it results in sign and value change of the STT. Further, the emergence of in-plane STTs in presence of SOC are confirmed and investigated for various systems.