bluuebunny/crossref_metadata_2025 huggingface dataset:
Computationally enhanced quantitative phase microscopy reveals autonomous oscillations in mammalian cell growth
Authors: Liu Xili , Oh Seungeun , Peshkin Leonid , Kirschner Marc W.
Published: October 2020

Significance

It has been a long-standing question in cell growth studies whether the mass of cells grows linearly or exponentially. The two models imply fundamentally distinct mechanisms, and discrimination of the two requires exceptional measurement accuracy. Here, we develop a method, computationally enhanced quantitative phase microscopy, which greatly improves the accuracy and throughput for single-cell growth measurements in adherent mammalian cells. Studies in several cell lines indicate that the growth dynamics of individual cells cannot be explained by either of the simple conventional models; rather, they present an unanticipated and remarkable oscillatory behavior, suggesting more complex regulation and feedbacks in growth, cell division, and size.
B3GALT5 knockout alters glycosphingolipid profile and facilitates transition to human naïve pluripotency
Authors: Lin Ruey-Jen , Kuo Ming-Wei , Yang Bei-Chia , Tsai Hsiu-Hui , Chen Kowa , Huang Jing-Rong , Lee Yun-Shien , Yu Alice L. , Yu John
Published: October 2020

Significance

These studies provide systematically characterized glycosphingolipid (GSL) profiles and expression level of glycosyltransferase upon the conversion of human ESCs from primed to naïve state. We identify a switch of GSL profile from globo- and lacto-series to neolacto-series GSLs, accompanied by the downregulation of β-1,3-galactosyltransferase (B3GALT5) during the pluripotency transition. The CRISPR/Cas9-generated
B3GALT5
knockout increases the level of intracellular Ca
2+
, resulting in an intermediate state of pluripotency, which facilitates the primed- to naïve-state transition in human ESCs. In addition, the altered GSL could be rescued through overexpression of B3GALT5. Thus, our results provide a new perspective in the understanding of human pluripotency transition from primed to naïve state, which can be facilitated by changing the expression of single glycosyltransferase, B3GALT5.
IL-36R signaling integrates innate and adaptive immune-mediated protection against enteropathogenic bacteria
Authors: Ngo Vu L. , Abo Hirohito , Kuczma Michal , Szurek Edyta , Moore Nora , Medina-Contreras Oscar , Nusrat Asma , Merlin Didier , Gewirtz Andrew T. , Ignatowicz Leszek , Denning Timothy L.
Published: October 2020

Significance

Upon enteropathogenic bacterial infection, cytokines orchestrate innate and adaptive immune activation that promotes barrier protection and pathogen control. Using
Citrobacter rodentium
, we defined a critical role for IL-36R signaling in driving early IL-23- and late IL-6-mediated IL-22 production, antimicrobial activity, and host protection. Our data show that the IL-36/IL-36R axis integrates innate and adaptive immune responses to afford host protection to enteropathogenic bacterial infection. These findings provide mechanistic insight into how the proinflammatory IL-36 pathway coordinates immunity and highlight the potential for targeting IL-36 cytokines and IL-36R in treating enteropathogenic bacterial infection.
Structural basis of Chikungunya virus inhibition by monoclonal antibodies
Authors: Zhou Qun Fei , Fox Julie M. , Earnest James T. , Ng Thiam-Seng , Kim Arthur S. , Fibriansah Guntur , Kostyuchenko Victor A. , Shi Jian , Shu Bo , Diamond Michael S. , Lok Shee-Mei
Published: October 2020

Significance

Chikungunya virus (CHIKV) is a significant human pathogen that causes debilitating and long-lasting arthritis. Currently, there is no approved vaccine or specific therapeutic. We show that two highly potent anti-CHIKV antibodies—CHK-124 and CHK-263—can inhibit multiple steps of the CHIKV infection cycle and determined their cryogenic electron microscopy structures in complex with CHIKV particles to a 4- to 5-Å resolution. We describe the structural details of the epitopes of CHK-124 and CHK-263 and how they relate to their functional mechanisms of neutralization. Our results provide important information that will advance antibody therapeutics and vaccine development against this emerging pathogen.
Phase separation at the nanoscale quantified by dcFCCS
Authors: Peng Sijia , Li Weiping , Yao Yirong , Xing Wenjing , Li Pilong , Chen Chunlai
Published: October 2020

Significance

Liquid–liquid phase separation causes formation of membraneless condensates containing concentrated biomolecules, which play essential roles in diverse cellular processes. Currently, micrometer-scale phase-separated condensates are examined routinely to elucidate their functions and mechanisms in details. However, limited by current commonly used methods, the transition process from miscible individual molecules to micrometer-scale condensates is mostly unknown. Herein, we captured formation of nanoscale condensates, whose size, growth rate, molecular stoichiometry, and binding affinity to recruit client molecules were all quantified. To achieve this, we developed a dual-color fluorescence cross-correlation spectroscopy (dcFCCS) method, and we expect that dcFCCS can be widely applied to investigate phase separation of other biomolecules at the nanoscale.
PLA2G6 guards placental trophoblasts against ferroptotic injury
Authors: Beharier Ofer , Tyurin Vladimir A. , Goff Julie P. , Guerrero-Santoro Jennifer , Kajiwara Kazuhiro , Chu Tianjiao , Tyurina Yulia Y. , St Croix Claudette M. , Wallace Callen T. , Parry Samuel , Parks W. Tony , Kagan Valerian E. , Sadovsky Yoel
Published: October 2020

Significance

Placental dysfunction has been causally linked to major pregnancy complications that are implicated in maternal–fetal morbidity and mortality, but the mechanisms underlying placental dysfunction are largely unknown. The recently identified ferroptotic cell death is characterized by excessive accumulation of hydroperoxide phosphatidylethanolamines. While oxidative damage commonly defines placental dysfunction, the role of ferroptosis in this process is largely unknown. We found that preterm birth is associated with ferroptotic signals, and that inhibition of GPX4, which converts unstable lipid hydroperoxides to nontoxic lipid alcohols, causes ferroptotic injury in primary human trophoblasts and in mouse pregnancy. Importantly, we found that the phospholipase PLA2G6 mitigates trophoblast and placental ferroptosis. Together, we identified placental ferroptosis and established a role for PLA2G6 in attenuating ferroptosis.
Experimentally determined strengths of favorable and unfavorable interactions of amide atoms involved in protein self-assembly in water
Authors: Cheng Xian , Shkel Irina A. , O’Connor Kevin , Record M. Thomas
Published: October 2020

Significance

Quantitative information about strengths of amide nitrogen−amide oxygen hydrogen bonds and π-system and hydrophobic interactions involving amide-context sp
2
and/or sp
3
carbons is needed to assess their contributions to specificity and stability of protein folds and assemblies in water, as well as to predict or interpret how urea and other amides interact with proteins and affect protein processes. Here we obtain this information from thermodynamic measurements of interactions between amide compounds in water and an analysis that determines intrinsic strengths of atom−atom interactions, relative to water and per unit area of each atom type present. These findings allow prediction or interpretation of effects of any amide on protein processes from structure, and may be useful to analyze protein interfaces.
Entropy-controlled cross-linking in linker-mediated vitrimers
Authors: Lei Qun-Li , Xia Xiuyang , Yang Juan , Pica Ciamarra Massimo , Ni Ran
Published: October 2020

Significance

The recently developed linker-mediated vitrimers based on metathesis reactions offer new possibilities of processing cross-linked polymers with high mechanical performance in industry, while the design principle remains unknown. Here we propose a theoretical framework for describing the system of linker-mediated vitrimers, in which entropy is found to play a dictating role. Our mean field theory agrees quantitatively with computer simulations, and provides guidelines for the rational design of the linker-mediated vitrimers with desired properties.
Extracellular cyclic dinucleotides induce polarized responses in barrier epithelial cells by adenosine signaling
Authors: Chang Denis , Whiteley Aaron T. , Bugda Gwilt Katlynn , Lencer Wayne I. , Mekalanos John J. , Thiagarajah Jay R.
Published: October 2020

Significance

Cyclic dinucleotides (CDNs) are important signaling molecules that are involved in many microbial processes and in the host cell response to intracellular pathogens. Intracellular CDN signaling is mediated by well-described sensor proteins; however, much less is known about how CDNs signal in the extracellular environment. Here we discover, in intestinal epithelial cells, that extracellular CDNs are hydrolyzed by enzymes present in the cell membrane to form adenosine and activate cell-surface adenosine receptors. This stimulates epithelial chloride secretion and inhibits cellular antiviral responses. Signaling originates exclusively from the serosal tissue-facing side of the epithelium. Our study implicates adenosine signaling as an important mechanism by which extracellular CDNs can modulate host defense at mucosal surfaces.
Liquid drop of DNA libraries reveals total genome information
Authors: Terekhov Stanislav S. , Eliseev Igor E. , Ovchinnikova Leyla A. , Kabilov Marsel R. , Prjibelski Andrey D. , Tupikin Alexey E. , Smirnov Ivan V. , Belogurov Alexey A. , Severinov Konstantin V. , Lomakin Yakov A. , Altman Sidney , Gabibov Alexander G.
Published: October 2020

Significance

DNA libraries are predisposed to template mispairing during conventional “bulk” PCR, leading to the loss of unique sequences. The latter is facilitated by the nonuniform distribution of templates frequently observed in DNA libraries. These effects result in a prominent reduction of the original diversity. The encapsulation of DNA repertoires in liquid droplets abolishes the effects of mispairing in DNA libraries. The fundamental advantages of emulsion PCR (ePCR) over bulk PCR are illustrated by deep sequencing and mathematical modeling, which provide the general strategy for ePCR rationalization. The quasi single-molecule ePCR reveals total genetic information by counteracting the degeneration of DNA libraries’ diversity.
Information design and multimodality
Authors: Bateman John A.
Published: October 2020

Despite a long association between information design and semiotics, connections remain limited in many respects. This contribution argues that one reason for this is the traditionally weak connection between semiotics and empirical methods. To counter this, a model of multimodal communication is introduced in which theoretical description and empirical research are tightly bound methodologically. Several illustrations of the relevance of the model for information design are offered.
Reaction Rate Weighted Multilayer Nuclear Reaction Network
Authors: Liu Huan-Ling , Han Ding-Ding , Ji Peng , Ma Yu-Gang
Published: October 2020

Nuclear reaction rate λ is a significant factor in processes of nucleosyntheses. A multi-layer directed-weighted nuclear reaction network, in which the reaction rate is taken as the weight, and neutron, proton, 4He and the remainder nuclei as the criteria for different reaction layers, is for the first time built based on all thermonuclear reactions in the JINA REACLIB database. Our results show that with the increase in the stellar temperature T
9, the distribution of nuclear reaction rates on the R-layer network demonstrates a transition from unimodal to bimodal distributions. Nuclei on the R-layer in the region of λ = [1,2.5 × 101] have a more complicated out-going degree distribution than that in the region of λ = [1011,1013], and the number of involved nuclei at T
9 = 1 is very different from the one at T
9 = 3. The redundant nuclei in the region of λ = [1, 2.5 × 101] at T
9 = 3 prefer (γ, p) and (γ,α) reactions to the ones at T
9 = 1, which produce nuclei around the β stable line. This work offers a novel way to the big-data analysis on the nuclear reaction network at stellar temperatures.
Fast frequency-domain effective fly-by waveforms
Authors: Loutrel Nicholas
Published: October 2020

Recently, we developed effective fly-by (EFB) waveforms designed to model the burst of gravitational radiation from highly eccentric binaries. We here present a faster to evaluate frequency domain EFB waveform. The waveform is constructed through the use of asymptotic expansions of hypergeometric functions. Since the waveform is fully analytic, we study the accuracy to which the binary’s parameters can be measured using a Fisher analysis. We find that degeneracies exist among the parameters, such that the waveform is parameterized in terms of the chirp mass

M

and orbital radius of curvature

P

, instead of the total mass, symmetric mass ratio, and semi-latus rectum of the binary. By computing the Fisher matrix for single bursts from two thousand binary systems, we find that most of the systems will have greater than one hundred percent uncertainty in the chirp mass, luminosity distance, and inclination angle, while roughly half will have less than one hundred percent uncertainty in the orbital radius of curvature, orbital eccentricity, and polarization angle. Further, we repeat this analysis after including additional bursts within the inspiral sequence and find that the uncertainties in the waveform’s parameters can improve by orders of magnitude with a sufficient timing model for the bursts.
Lorentzian spectral geometry with causal sets
Authors: Yazdi Yasaman K , Letizia Marco , Kempf Achim
Published: October 2020

We study discrete Lorentzian spectral geometry by investigating to what extent causal sets can be identified through a set of geometric invariants such as spectra. We build on previous work where it was shown that the spectra of certain operators derived from the causal matrix possess considerable but not complete power to distinguish causal sets. We find two especially successful methods for classifying causal sets and we computationally test them for all causal sets of up to 9 elements. One of the spectral geometric methods that we study involves holding a given causal set fixed and collecting a growing set of its geometric invariants such as spectra (including the spectra of the commutator of certain operators). The second method involves obtaining a limited set of geometric invariants for a given causal set while also collecting these geometric invariants for small ‘perturbations’ of the causal set, a novel method that may also be useful in other areas of spectral geometry. We show that with a suitably chosen set of geometric invariants, this new method fully resolves the causal sets we considered. Concretely, we consider for this purpose perturbations of the original causal set that are formed by adding one element and a link. We discuss potential applications to the path integral in quantum gravity.
Instructor’s dilemma: requiring two-dimensional measurements to describe one-dimensional motion, applied to a person walking
Authors: Diener J P W , Kriek J
Published: October 2020

Introductory physics courses uses simplified models and approximations to convey fundamental concepts. Many of these simplifications are introduced without explanation. When considering motion, one such simplification is the point particle approximation. That is to assume that the motion of an extended object can be represented by the motion of a single point, generally the object’s centre of mass. For some objects the exact position of the centre of mass could be difficult to locate and the procedure beyond the scope of an introductory course. Furthermore, if the object changes its shape while in motion, thereby redistributing its mass, the relative position of the centre of mass also changes. In such instances the physical measurements of the object’s position could be rather complicated, especially if the task is to choose one physical marker on the object that best represents its motion. If the object is travelling in a straight line [one-dimensional (1D) motion] and the motion of physical marker does not closely match that of the object, a two-dimensional measurement would be required to describe 1D motion. Hereby instructors might be challenged to explain seemingly simple phenomena, like determining the position of an object, within the confines of the introductory course. In order to assist instructors in this regard, we present an experimental measurement procedure which aims to minimize the error in position measurements of objects that changes their shape while in motion. We apply the procedure to determine the position of a walking person.
Shock waves in pulsed electrical discharges in liquids: numerical simulation and comparison to experiment
Authors: Jimenez Francisco J , Radfar Marjan , Kirk Braedan , Sydora Richard D , Hunter Trent S
Published: October 2020

In this paper a computational model for the post-breakdown phase of an electrical discharge in liquids is presented and validated through comparison with data from a high voltage pulsed power discharge in a water-filled crucible. The numerical framework consists of an arc plasma channel modeled by equivalent resistor-inductor-capacitor circuit equations coupled to a computational fluid dynamics (CFD) model (based on OpenFOAM) that solves the compressible fluid equations for describing the shock waves associated with the rapid development of the plasma channel. The circuit model equations evolve the initial discharge plasma expansion which are then used to initialize the pressure pulse in the CFD model. Both single-phase (liquid) and two-phase (gas–liquid) CFD solvers were implemented and compared. The dynamics and magnitude of the simulated pressure pulse perturbations at the boundaries of the crucible were validated with the pressure sensor measurements made in an experiment of a pulsed electrical discharge in liquid water.
One-dimensional nanomaterials in lithium-ion batteries
Authors: Jaramillo-Cabanzo D F , Ajayi B P , Meduri P , Sunkara M K
Published: October 2020

A lot of progress has been made in rechargeable lithium-ion battery (LIB) technology research in the last decade, even so, renewed developmental efforts must be pursued to better improve energy density, capacity retention and rate capability. This review discusses the role that one-dimensional (1D) nanomaterials can play towards development of next-generation LIBs. Electrode nanoengineering, interfacial kinetics and high-volume manufacturing are critical issues limiting energy density, electrochemical performance and material viability. These points are discussed, as are the advantages of deploying these nanomaterials in rechargeable LIB devices. Current data from literature is indicative of laboratory-scale success as these 1D nanomaterials display excellent capacity retention, high-rate capability and long cycle life emanating from high mechanical strength, resilience and short charge carrier diffusion distance. However, significant advances are required to translate these achievements into commercial scale deployment.
A high numerical aperture terahertz all-silicon metalens with sub-diffraction focus and long depth of focus
Authors: Wang Zewen , Li Qi , Yan Fei
Published: October 2020

A high numerical aperture (NA = 0.92) square all-silicon metalens is designed for a wavelength of λ= 0.11883 mm with a focal length of 16.8λ and a side length of 104.4λ. Based on the waveguide effect, anisotropic rectangular silicon pillars with different dimensions are arranged on the silicon substrate according to the conical phase distribution, and then the rotation angle of each rectangular pillar is adjusted to realize the polarization conversion. Furthermore, a polarization-independent square antireflection silicon pillar array is proposed to be patterned at the other side of the substrate. The metalens can efficiently convert the normally incident x- (or y-) polarized plane wave into the radially (or azimuthally) polarized beam and conduct the sub-diffraction tight-focusing simultaneously, thus the shape of the focus can be flexibly switched. The numerical simulation results show that, under high-NA conditions, our metalens can obtain a tighter focus compared with linearly polarized metalens and a longer depth of focus (DOF) compared with metalens based on the hyperboloidal phase distribution. Under x- (or y-) polarized plane wave incidence, a circular-spot-shaped (or doughnut-shaped) focus with a full width at half maximum of 0.4λ (or 0.3λ) is obtained and the DOF is 26.509λ (or 18.935λ). In addition, under x-polarized beam incidence, the influence of the incident beam intensity distribution on the focusing results is also discussed. The use of a single material makes our metalens more favorable in fabrication and it is expected that our study is of great significance for applying terahertz wave in imaging and communication systems, high-resolution microscopy, optical coherence tomography and manipulation of particles.
Pseudo-spin rotation symmetry breaking by Coulomb interaction terms in spin–orbit coupled systems
Authors: Mohapatra Shubhajyoti , Singh Avinash
Published: October 2020

By transforming from the pure-spin-orbital (t
2g) basis to the spin-orbital entangled pseudo-spin-orbital basis, the pseudo-spin rotation symmetry of the different Coulomb interaction terms is investigated under SU(2) transformation in pseudo-spin space. While the Hubbard and density interaction terms are invariant, the Hund’s coupling and pair-hopping interaction terms explicitly break pseudo-spin rotation symmetry systematically. The form of the symmetry-breaking terms obtained from the transformation of the Coulomb interaction terms accounts for the easy x–y plane anisotropy and magnon gap for the out-of-plane mode, highlighting the importance of mixing with the nominally non-magnetic J = 3/2 sector, and providing a physically transparent approach for investigating magnetic ordering and anisotropy effects in perovskite (Sr2IrO4) and other d
5 pseudo-spin compounds.
Magnetic properties of γ-Fe2O3 nanoparticles in a porous SiO2 shell for drug delivery
Authors: Kamali S , Yu E , Bates B , McBride J R , Johnson C E , Taufour V , Stroeve P
Published: October 2020

A method is presented for synthesizing core–shell nanoparticles with a magnetic core and a porous shell suitable for drug delivery and other medical applications. The core contains multiple γ-Fe2O3 nanoparticles (∼15 nm) enclosed in a SiO2 (∼100–200 nm) matrix using either methyl (denoted TMOS-γ-Fe2O3) or ethyl (TEOS-γ-Fe2O3) template groups. Low-temperature Mössbauer spectroscopy showed that the magnetic nanoparticles have the maghemite structure, γ-Fe2O3, with all the vacancies in the octahedral sites. Saturation magnetization measurements revealed that the density of γ-Fe2O3 was greater in the TMOS-γ-Fe2O3 nanoparticles than TEOS-γ-Fe2O3 nanoparticles, presumably because of the smaller methyl group. Magnetization measurements showed that the blocking temperature is around room temperature for the TMOS-γ-Fe2O3 and around 250 K for the TEOS-γ-Fe2O3. Three dimensional topography analysis shows clearly that the magnetic nanoparticles are not only at the surface but have penetrated deep in the silica to form the core–shell structure.
Electronic, phononic and superconducting properties of trigonal Li2
MSi2 (M
= Ir, Rh)
Authors: Tayran C , Çakmak M
Published: October 2020

We have used ab initio density functional theory to study electronic, mechanical, phononic, and superconducting properties of Li2
MSi2 (M = Ir, Rh), which has recently been produced as a new type of transition metal–based ternary compound in the trigonal structure (Horigane et al 2019 New J. Phys.
21 093056). The calculated electronic band structure and the density of states indicate that the Li2IrSi2 and Li2RhSi2 compounds are in metallic character. Mechanical properties such as elastic constants, bulk modulus, shear modulus, Young’s modulus, Poisson’s ratio, and Debye temperature were calculated for these compounds. The calculated results suggest that the compounds are mechanically stable and behave in a ductile manner. The phonon spectra have no imaginary frequency, which proves that these compounds are dynamically stable. Electron–phonon coupling parameters confirm that they are weak–coupling superconductors. Although the influence of spin–orbit coupling in superconductivity is not significant for these compounds, it has a very small influence on electronic structure for Li2IrSi2. The calculated critical temperature (

T

c

μ

⋆

=
0.11

) values of 3.29 K for Li2IrSi2 and 2.82 K for Li2RhSi2 agree well with experimental estimates.
Anion ordering transition and Fermi surface electron–hole instabilities in the (TMTSF)2ClO4 and (TMTSF)2NO3 Bechgaard salts analyzed through the first-principles Lindhard response function
Authors: Guster Bogdan , Pruneda Miguel , Ordejón Pablo , Canadell Enric , Pouget Jean-Paul
Published: October 2020

The first-principles electron–hole Lindhard response function has been calculated and analyzed in detail for two (TMTSF)2
X (X = ClO4 and NO3) Bechgaard salts undergoing different anion-ordering (AO) transitions. The calculation was carried out using the real triclinic low-temperature structures. The evolution of the electron–hole response with temperature for both relaxed and quenched salts is discussed. It is shown that the 2k
F response of the quenched samples of both salts display a low temperature curved and tilted triangular continuum of maxima. This is not the case for the relaxed samples. (TMTSF)2ClO4 in the AO state exhibits a more quasi-1D response than in the non AO state and relaxed (TMTSF)2NO3 shows a sharp maximum. The curved triangular plateau of the quenched samples results from multiple nesting of the warped quasi-1D Fermi surface which implies the existence of a large q range of electron–hole fluctuations. This broad maxima region is around 1% of the Brillouin zone area for the X = ClO4 salt (and X = PF6) but only 0.1% for the X = NO3 salt. It is suggested that the strong reduction of associated SDW fluctuations could explain the non detection of the SDW-mediated superconductivity in (TMTSF)2NO3. The calculated maxima of the Lindhard response nicely account for the modulation wave vector experimentally determined by NMR in the SDW ground state of the two salts. The critical AO wave vector for both salts is located in regions where the Lindhard response is a minimum so that they are unrelated to any electron–hole instability. The present first-principles calculation reveals 3D effects in the Lindhard response of the two salts at low temperature which are considerably more difficult to model in analytical approaches.
Quantitative identification of independent and dependent sources based on bounded component analysis
Authors: Gong Teng , Zhang Zhousuo , Luo Xin , Li Yongjie
Published: October 2020

The quantitative identification of vibration sources can provide the basis and guidance for the vibration and noise reduction of mechanical systems. Since the vibration sources in a mechanical system are not necessarily mutually independent, this paper proposes a quantitative identification method suitable for both independent and dependent sources based on bounded component analysis (BCA). Firstly, the new BCA algorithm is adopted to separate source signals and normalized boundary minimization is used as the objective function, which is optimized by a modified subgradient method with the introduction of the probability mass function and an adaptive step size, and thus the noise resistance and convergence performance are enhanced. Secondly, the source contribution is extracted by taking the separated signal as the input and boundary minimization of the residual signal as the criterion. Thirdly, the projection of the source contribution in the mixed signal is calculated by the inner product and the proportion of the calculated projection on the mixed signal is taken as the contribution index to evaluate the influence of the vibration source on the vibration of the observation point of the system. Finally, the effectiveness and superiority of the proposed method are tested by simulation analysis and experimental verification. The results show that the proposed method has high accuracy in the quantitative identification of both independent and dependent sources.
Assembling your nanowire: an overview of composition tuning in ternary III–V nanowires
Authors: Ghasemi Masoomeh , Leshchenko Egor D , Johansson Jonas
Published: October 2020

The ability to grow defect-free nanowires in lattice-mismatched material systems and to design their properties has made them ideal candidates for applications in fields as diverse as nanophotonics, nanoelectronics and medicine. After studying nanostructures consisting of elemental and binary compound semiconductors, scientists turned their attention to more complex systems—ternary nanowires. Composition control is key in these nanostructures since it enables bandgap engineering. The use of different combinations of compounds and different growth methods has resulted in numerous investigations. The aim of this review is to present a survey of the material systems studied to date, and to give a brief overview of the issues tackled and the progress achieved in nanowire composition tuning. We focus on ternary III
x
III1−x
V nanowires (AlGaAs, AlGaP, AlInP, InGaAs, GaInP and InGaSb) and IIIV
x
V1−x
nanowires (InAsP, InAsSb, InPSb, GaAsP, GaAsSb and GaSbP).
Facile one-step hydrothermal synthesis of single-crystalline SnNb2O6 nanosheets with greatly extended visible-light response for enhanced photocatalytic performance and mechanism insight
Authors: Liu Qianqian , Zhang Quan , Liu Bo , Dai Wei-Lin
Published: October 2020

The conventional preparation of SnNb2O6 invariably involves complex and laborious steps, which unavoidably introduces defect into the host lattice and also increases the reaction period and costs, resulting in undesired recombination of photo-generated electron–hole pairs. For the first time in this work, we manage to synthesize single-crystalline two-dimensional (2D) SnNb2O6 nanosheets with ultrathin structure through a facile one-step hydrothermal method. Comparative studies were explored to analyze the structure and phase evolution during the preparation course. The synthesized 2D structure demonstrated a narrower band gap of 2.09 eV and specific surface area of 76.1 m2 g−1, which exhibited significantly extended visible-light-responsive range and larger surface area by contrast with the state-of-the-art reports, resulting in excellent visible-light-driven photoactivity towards H2 production and water purification as well. Additionally, further enhanced photocatalytic performance was achieved by the incorporation of Pt as co-catalyst to indirectly indicate the advantage of the SnNb2O6 nanosheets in this method over other reported counterparts. It was found that, a very small amount of Pt loaded on the surface of SnNb2O6 nanosheets would contribute to remarkably higher activity than pure SnNb2O6 nanosheets and exhibit superior stability as well. Moreover, a deep insight into the underlying photocatalytic mechanism was proposed. This work sheds light on a new facile way to fabricate high-performance photocatalytic materials and provided new opportunities for solar-energy conversion.
All-dielectric multifunctional transmittance-tunable metasurfaces based on guided-mode resonance and ENZ effect
Authors: Qiu Xiaoming , Shi Jian , Li Yanping , Zhang Fan
Published: October 2020

Electrically tunable metasurfaces open new doors for manipulating the phase, amplitude and polarization of light in ultrathin layers. Compared with metal assisted metasurfaces, all-dielectric transmission metasurfaces—with outstanding feature of low loss, especially incorporating with new electro-optical materials—show great potential for the next generation flat optics. In this study, by combining the epsilon-near-zero effect in indium tin oxide (ITO) with guided-mode resonance, we propose novel electrically tunable all-dielectric metasurface architectures with versatile functions for widespread potential application. The inserted periodic ITO and hafnium oxide layers sandwiched in silicon act as two metal-oxide-semiconductor capacitors in a single period to disturb the resonance wavelength in the near-infrared spectral range under the voltage applied. For the one-dimensional structure, the transmittances of this metasurface at 1512 and 1510 nm change 20 and −14 dB under 0∼5 V bias voltage, respectively. In addition, the bilayer structure performs well in double-waveband applications, indicating that more layers can support more operation wavebands. Meanwhile, the two-dimensional structure works as a polarization insensitive device when setting the same structural parameters in both orthogonal directions. The proposed architecture, with various merits including ultra-compact size, high-speed and complementary metal-oxide-semiconductor compatibility, provides a multifunctional and multi-degree-of-freedom design, as well as enormous potential applications in more complicated flat optics.
Existence of stationary stochastic Burgers evolutions on R
2 and R
3

*
Authors: Dunlap Alexander
Published: October 2020

We prove that the stochastic Burgers equation on R

d
, d < 4, forced by gradient noise that is white in time and smooth in space, admits spacetime-stationary solutions. These solutions are thus the gradients of solutions to the KPZ equation on R

d
with stationary gradients. The proof works by proving tightness of the time-averaged laws of the solutions in an appropriate weighted space.
The mean-field equation of a leaky integrate-and-fire neural network: measure solutions and steady states
Authors: Dumont Grégory , Gabriel Pierre
Published: October 2020

Neural network dynamics emerge from the interaction of spiking cells. One way to formulate the problem is through a theoretical framework inspired by ideas coming from statistical physics, the so-called mean-field theory. In this document, we investigate different issues related to the mean-field description of an excitatory network made up of leaky integrate-and-fire neurons. The description is written in the form a nonlinear partial differential equation which is known to blow up in finite time when the network is strongly connected. We prove that in a moderate coupling regime the equation is globally well-posed in the space of measures, and that there exist stationary solutions. In the case of weak connectivity we also demonstrate the uniqueness of the steady state and its global exponential stability. The method to show those mathematical results relies on a contraction argument of Doeblin’s type in the linear case, which corresponds to a population of non-interacting units.
Semiclassical states for Choquard type equations with critical growth: critical frequency case
*
Authors: Ding Yanheng , Gao Fashun , Yang Minbo
Published: October 2020

In this paper we are interested in the existence of semiclassical states for the Choquard type equation

−

ε

2

Δ
u
+
V

(

x

)

u
=

∫

R

N

G

(

u

(

y

)

)

|
x
−
y
|

μ

d
y

g

(

u

)

in

R

N

,

where 0 < μ < N, N ⩾ 3, ɛ is a positive parameter and G is the primitive of g which is of critical growth due to the Hardy–Littlewood–Sobolev inequality. The potential function V(x) is assumed to be nonnegative with V(x) = 0 in some region of

R

N

, which means it is of the critical frequency case. Firstly, we study a Choquard equation with double critical exponents and prove the existence and multiplicity of semiclassical states by the mountain-pass lemma and the genus theory. Secondly, we consider a class of critical Choquard equation without lower perturbation, by establishing a global compactness lemma for the nonlocal Choquard equation, we prove the multiplicity of high energy semiclassical states by the Lusternik–Schnirelman theory.
Real-time measurement of isometric peak torque and rate of torque development using a novel strength testing device: a validity and reliability study
Authors: Palmer Ty B , Blinch Jarrod , Farrow Ahalee C , Agu-Udemba Chinonye C , Mitchell Ethan A
Published: October 2020

Objective: Isometric peak torque (PT) and rate of torque development (RTD) are important characteristics relevant to athletic performance. A novel device called the Dynamo Torque Analyzer calculates and displays real-time measurements of isometric PT and RTD. However, the ability of the Dynamo to provide valid and reliable isometric PT and RTD measurements similar to those of an isokinetic dynamometer remains unclear. This study aimed to compare the reliability and magnitude of isometric leg extension and flexion PT and RTD measurements between an isokinetic dynamometer and the Dynamo Torque Analyzer. Approach: Twenty healthy, recreationally-active adults (age = 22 ± 3 years; height = 169 ± 10 cm; mass = 71 ± 18 kg) performed three isometric leg extension and flexion maximal voluntary contractions on two different occasions, from which isometric PT and early (RTD100), late (RTD200), and maximum (Peak RTD) RTD characteristics were measured by an isokinetic dynamometer and the Dynamo. Main results: Isometric leg extension and flexion PT and RTD characteristics were highly consistent across sessions for both the isokinetic dynamometer and Dynamo devices, with intraclass correlation coefficients of 0.935–0.984 and standard errors of measurement expressed as a percentage of the mean of 4.93–14.46%. There were significant positive relationships between the isokinetic dynamometer and Dynamo for all PT and RTD characteristics (r ≥ 0.994; P < 0.001). Moreover, no significant differences between devices were observed for these variables (P = 0.107–0.555). Significance: These findings suggest that the Dynamo Torque Analyzer may be a valid and reliable device for measuring isometric PT and RTD of the lower-body musculature.
Optimization of finite-sized modular coils for advanced stellarators
Authors: Li Yangbo , Liu Haifeng , Xu Yuhong , Shimizu Akihiro , Kinoshita Shigeyoshi , Okamura Shoichi , Isobe Mitsutaka , Xiong Guozhen , Luo Yang , Cheng Jun , Liu Hai , Wang Xianqu , Huang Jie , Zhang Xin , Yin Dapeng , Wan Yi , Tang Changjian
Published: October 2020

To date, almost all coil-design codes, e.g. NESCOIL, COILOPT, FOCUS codes, etc, have been primarily attributed to the optimization of filament coils for stellarators. However, evolving to a practical/finite-sized coil from a filament coil, the finite-size effect of coils significantly constrains the fabrication tolerances of a coil system. This paper presents a novel approach that emphasizes the optimization of practical modular coils to reduce sensitivity to fabrication tolerances and to achieve the expected magnetic configurations precisely. A new evaluation parameter, surface twist, is defined in this paper and applied to the optimization sequence in addition to the practical coil line torsion and curvature. The approach has been applied to the framework of the filament coil scheme in the Chinese first quasi-axisymmetric stellarator. This practical coil system without surface twists has been accomplished. Compared to the original finite-sized coil design, the new result is a more considerable simplification of coil shapes, such that in a certain direction view each finite-sized coil becomes a planar-like one. Moreover, this method can also be implemented for the estimation of stochastic deviations of practical coils during the fabrication and assembly of the coil system.
Peculiarities of spatial relaxation of the mean electron energy in inert gases and their mixtures in a uniform electric field
Authors: Dyatko N A , Kochetov I V , Ochkin V N
Published: October 2020

A theoretical study of the spatial relaxation characteristics of the mean electron energy in a uniform electric field in He, Ne, Ar, Kr, Xe and a mixture of He:Xe was performed. Calculations were carried out with the use of the Monte Carlo technique. Electrons were launched at some point z = 0, and the electron energy distribution function and the mean electron energy u
m(z) were calculated at various distances from the source. According to calculations, for pure gases in a wide range of the electric field strength E, the dependence u
m(z) has the form of damped oscillations. At that, the relaxation length L and the oscillation period Λ are almost independent of the form of the energy spectrum of the electron source. It is shown that for all pure gases the calculated dependences L(E) have the shape of a hump, and for each gas the position of the maximum corresponds to such E values at which the energy lost by electrons in elastic collisions is about 4%–8%. For the case of Xe we also studied the variation of L(E) depending on the set of cross sections used in the calculations. It was also shown that for the same E value, the relaxation length in He:Xe mixture differs significantly from that in pure He or Xe. Moreover, u
m(z) in a certain range of parameters (E and percentage of Xe in the gas mixture) is characterized by the sum of two damped oscillations with different spatial periods.
Scaling of pulsed nanosecond capillary plasmas at different specific energy deposition
Authors: Zhu Yifei , Starikovskaia Svetlana M , Babaeva Natalia Yu , Kushner Mark J
Published: October 2020

Nano-second, capillary discharges (nCDs) are unique plasma sources in their ability to sustain high specific energy deposition ω
dep approaching 10 eV/molecule in molecular gases. This high energy loading on short timescales produces both high plasma densities and high densities of molecular exited states. These high densities of electrons and excited states interact with each other during the early afterglow through electron collision quenching and associative ionization. In this paper we discuss results from a two-dimensional computational investigation of a nCD sustained in air at a pressure of 28.5 mbar and with a voltage amplitude 20 kV. Discharges were investigated for two circuit configurations—a floating low voltage electrode and with the low voltage electrode connected to ground through a ballast resistor. The first configuration produced a single ionization wave from the high to low voltage electrode. The second produced converging ionization waves beginning at both electrodes. With a decrease of the tube radius, the velocity of the ionization fronts decreased while the shape of the ionization wave changed from the electron density being distributed smoothly in the radial direction, to being hollow shaped where there is a higher electron density near the tube wall. For sufficiently small tubes, the near-wall maxima merge to have the higher density on the axis of the capillary tube. In the early afterglow, the temporal and radial behavior of the N2(C3Πu) density is a sensitive function of ω
dep due to electron collision quenching. These trends indicate that starting from ω
dep ⩾ 0.3 eV/molecule, it is necessary to take into account interactions of electrons with electronically excited species during the discharge and early afterglow.
Matrix techniques for Lamb-wave damage imaging in metal plates
Authors: Neubeck Robert , Kexel Christian , Moll Jochen
Published: October 2020

The implementation of efficient maintenance strategies of thin-walled structural components require reliable damage detection and localization techniques. In particular, guided ultrasonic waves technology represent an auspicious approach when implemented in a structural health monitoring system. The method is usually based on distributed sensing with piezoelectric elements that act in turn as ultrasound transmitter and receiver. This work aims at a unifying framework for damage localization considering algorithms from different scientific disciplines, e.g. originated from radar and geophysics. Here, we systematically express those algorithms in matrix form and compare the respective damage localization performance with experimental measurements considering an isotropic specimen with a single and also multiple simultaneous defects. In addition, we evaluate the algorithms’ point spread function and propose performance metrics to quantitatively compare the imaging success.
Flexible and wearable wristband for harvesting human body heat based on coral-like PEDOT:Tos-coated nanofibrous film
Authors: Zhang Xuefei , Li Ting-Ting , Ren Hai-Tao , Peng Haokai , Jiang Qian , Wu Liwei , Shiu Bing‐Chiuan , Wang Yanting , Lou Ching-Wen , Lin Jia-Horng
Published: October 2020

A flexible and wearable thermoelectric wristband consisting of a poly(3,4-ethylenedioxythiophene):p-toluenesulfonic acid (PEDOT:Tos)-coated nanofibrous film (P-type legs) and a Ag nanoparticle-coated nanofibrous film (N-type legs) is constructed to realize the thermoelectric conversion by harvesting of the human body heat. Here, P-type legs are prepared via low-temperature in-situ interfacial polymerization, and a coral-like structure is formed on nanofiber. The resultant P-type leg exhibits a high electrical conductivity of 24.50 S cm−1 and a Seebeck coefficient of 13.67 μV K−1 at a temperature difference (ΔT) of 30 °C. Meanwhile, the N-type legs are fabricated via facile wet electroless deposition exhibits an electrical conductivity of 100 S cm−1. Thus, the constructed fiber-based wristband comprises of seven pairs of P-N legs, and can generate a maximum voltage of ∼0.18 mV at ΔT = 10 °C between user’s skin and the environment. Meanwhile, power is up to 101.51 pW after swinging the arm for 5 min. This thermoelectric wristband successfully completes the recycling of the human body heat and provides a new strategy for developing textile-based thermoelectric devices and monitoring human intelligence.
A dynamic gravimetric standard for liquid flow measurements
Authors: Saba F , Malengo A , Santiano M
Published: October 2020

An improved primary method for the calibration of liquid flow meters based on dynamic weighing has been adopted at the Istituto Nazionale di Ricerca Metrologica. Compared to the other dynamic methods currently in use, based on submerged liquid jet flows, the proposed method has the advantage of not requiring the correction for the hydrostatic buoyancy force exerted on the immersed tube. This is possible since the immersion depth of the tube is held constant during the dynamic weighing process, entailing, consequently, a constant back pressure at the outlet section of the immersed tube and a more stable liquid meniscus at the tube outer surface, which both improve the accuracy of measurement. Although at present the proposed apparatus has been tested in the range between 10 kg h−1 and 60 kg h−1, this improved dynamic method would be particularly suitable for lower flow rate as well. The results have shown that relative uncertainties of the order of 0.01% can be obtained.
Observation of non-thermal electron formation during the thermal quench of shattered pellet injection shutdowns in DIII-D
Authors: Hollmann E.M. , Shiraki D. , Baylor L. , Bykov I. , Eidietis N.W. , Golovkin I. , Herfindal J.L. , Lvovskiy A. , McLean A. , Moyer R.A. , O’Gorman T. , Parks P.B. , Popović Ž.
Published: October 2020

Formation of non-thermal (hot) electrons is studied during the thermal quench of shattered pellet injection (SPI) discharge shutdowns in the DIII-D tokamak. Both pure neon and mixed neon/deuterium shutdowns are studied. High-energy radiation (SXR and EUV) brightness levels show indications of non-thermal electron formation during the TQ. The non-thermal densities are of order 1018 m−3 and non-thermal temperatures are estimated to be of order 10 keV. The non-thermal electrons appear to be mostly lost during the subsequent current quench, as no signal of relativistic runaway electrons is typically seen at the end of the current quench. The non-thermals appear to have an effect on the deposition profile of the SPI pellets, especially at the end of the TQ, due to increased pellet ablation.