bluuebunny/crossref_metadata_2025 huggingface dataset:
Formation of photoelectron spectra of alloys niobium-molybdenum-zirconium
Authors: Ergashov Yokub , Donaev Burkhon , Khudainazarov Sherzod , Normuminov Jakhongir
Published: June 2021

Crystals of niobium and its alloys obtained by low-energy implantation of molybdenum and zirconium ions were studied in a multi-functional installation. The energy distribution curves of N (E) photoelectrons before and after heating niobium – molybdenum – zirconium alloys were studied. The contribution of surface zones formed by molybdenum and zirconium atoms to photoelectron emission in the photon energy region of 8–10 eV was analyzed.
Trends in Improving Sensors for Controlling the Condition of Track Sections
Authors: Aliev Ravshan
Published: June 2021

Various principles can be used to implement intelligent track circuits: voltage regulation of the power supply, compensation methods for switching on rail lines and track circuit devices, receiver sensitivity adjustment, comparison of two electrical parameters of one, two, or more track circuits, as well as a combination of these methods. At present, such improvement of track circuits is becoming relevant, which would make it possible to exclude from the circuits one of the most unreliable elements - an insulating joint, use a modern microprocessor element base in devices for monitoring the state of track sections, thus ensure their reliable operation. This will significantly reduce the costs of building and operating interval control systems and increase train traffic safety. These requirements are met by intelligent track circuits, which consider the current value of the insulation resistance, the rate of change of this resistance, and the longitudinal asymmetry.
Functional features of the automated accounting and control system of signalling, centralization and blocking devices
Authors: Baratov Dilshod
Published: June 2021

The article illustrates the functional features of the automated system of operation of signalling, centralization and blocking devices, shows the interface of the automated system of accounting and control of railway automation and telemechanics devices, presents the system requirements and testing of the automated method. The process manages, and metering devices of automatics and telemechanics in the use of QR-coding method should be used for automated identification of devices of signalling, centralization and blocking with the aim of collecting data about installed devices, checking the correct replacement devices, data input on the implementation of the repair and acceptance, automated input of data on new devices submitted for repair and process areas.
Numerical study of nonlinear problems in the dynamics of thin-walled structural elements
Authors: Kucharov Olim , Turaev Fozil , Leonov Sergey , Komilova Kholida
Published: June 2021

Mathematical model of the problem of vibration of thin-walled structural elements has been constructed based on Kirchhoff-Love theory. The problem is reduced, using the Bubnov-Galerkin method, to the solution of a set of nonlinear integro-differential Volterra type equations with weakly-singular kernels of relaxation. A numerical method based on the use of quadrature formulae being used for their solution. The influence of rheological parameters of the material on the values of critical velocity and amplitude-frequency characteristics of viscoelastic thin-walled structural elements is analyzed. It is shown that tacking account viscoelastic properties of the material of thin-walled structures lead to a decrease in the critical rate of gas flow.
Adaptation des installations nucléaires : une approche de plus en plus systémique
Authors:   La rédaction
Published: June 2021

En France, les installations nucléaires ont intégré les aléas climatiques dès leur conception et se sont adaptées aux évolutions. C’est le cas notam-ment pour le site Orano Tricastin dans la gestion de ses rejets d’effluents et plus globalement pour le parc nucléaire en France. Le point avec Frédéric Brun, ingénieur prévention des risques chez Orano et Catherine Halbwachs, chargée de mission climat à la Direction de la production nucléaire et thermique (DPNT) d’EDF, qui ont eu l’opportunité de s’exprimer lors du webinaire de la Sfen le 19 janvier 2021.
Baby on board – ein Beratungsleitfaden für Reisen mit Kindern
Authors: Hiestand Jasmin , Relly Christa , De Crom-Beer Susan , Fehr Jan , Kotsias-Konopelska Sarah
Published: June 2021

Reisen mit Babys und Kindern bringt sowohl für Eltern als auch für die reisemedizinische Beratung besondere Herausforderungen. Insbesondere Kinder von VFR (visiting friends and relatives) sind oft aufgrund einer verminderten Risikoperzeption und erhöhter Expositon einem erhöhten Risiko für Infektionskrankheiten ausgesetzt. Eine gute Vorbereitung hilft dabei, beim Welterkunden gesund zu bleiben. In der pädiatrischen Reiseberatung sind neben Reiseimpfungen, Moskitoschutz und Malariaprophylaxe ein sorgfältiger Sonnenschutz, Rehydrierung bei Gastroenteritis, Schutz vor Tollwutexposition, eine auf das Alter angepasste Reiseapotheke und vieles mehr anzusprechen. Wir geben einen Beratungsleitfaden für die wichtigsten Aspekte der Reiseberatung für Familien mit Kindern ab.
Zur Geschichte der Höhensanatorien in „Deutsch-Ostafrika“
Authors: Jüttemann Andreas
Published: June 2021

Im Jahr 1914 endete der Betrieb in den deutschen Höhensanatorien und medizinischen Forschungseinrichtungen in „Deutsch-Ostafrika“ (heute Tansania). In den Kureinrichtungen sollte nicht die Malaria kuriert werden (hierfür wurden Medikamente wie Chinin verabreicht), sondern die Höhe diente der Rehabilitation der geschwächten (europäischen) Kranken im Kolonialgebiet. Die wichtigste Einrichtung, die im folgenden Beitrag vorgestellt werden soll, war das Lienhardt-Sanatorium in dem für seine Veilchen bekannten Usambara-Gebirge.
OT in India – Ergotherapie in Indien
Authors: Sircar Ayla , Schiewack Michael
Published: June 2021

Die Akademisierung der Ergotherapie ist in Indien bereits seit vielen Jahren etabliert. Ayla Sircar gibt einen Überblick, wie sich die indische Ergotherapie von ihren Ursprüngen bis heute entwickelt hat.
Grenzüberschreitung – Sexuelle Belästigung im therapeutischen Setting
Authors: Schug Corinna
Published: June 2021

Corinna Schug sah sich selbst stets als taffe und schlagfertige Frau – bis einer ihrer Klienten einen folgenschweren Satz fallen ließ, der sie sehr irritierte. In diesem Erfahrungsbericht beschreibt die Ergotherapeutin, was ihr dabei half, mit der sexuellen Belästigung umzugehen.
Hintergründe der Versorgungskrise mit FFP2-Masken
Authors: Wurster Werner H.
Published: June 2021

Im Frühjahr 2020 hatten sich große Sorgen und teilweise sogar Angstgefühle beim ärztlichen und pflegerischen Personal eingestellt: Obwohl dieses an schwer kranken Patienten mit der hoch ansteckenden COVID-19-Erkrankung arbeiten musste, zeichnete sich ein eklatanter Mangel an persönlicher Schutzausrüstung (PSA), insbesondere an FFP2-Masken, ab. Gleichzeitig konnten Millionen importierte Schutzmasken nicht sofort und problemlos in Verkehr gebracht werden. Solche Verzögerungen wurden nicht durch „Prüfchaos“ in Behörden verursacht, wie es vielfach wahrgenommen wurde. Vielmehr wurde intensiv und zeitaufwendig die Qualität sehr vieler Angebote gleichzeitig geprüft, um die notwendige Schutzwirkung der Masken gewährleisten zu können (Abb. 1).
Mundtrockenheit – Was Sie selbst tun können
Authors: März Henrike
Published: June 2021

Ausreichend trinken, gelb-orange-rotes Obst und Gemüse verzehren, die Mundschleimhaut pflegen und gut kauen
Zimt
Authors: Stange Rainer
Published: June 2021

Wer glaubt, Zimt sei nur in der Weihnachtszeit interessant, täuscht sich – Es handelt sich um eine uralte Heilpflanze für Ganzjahresbeschwerden, der sich möglicherweise eine glänzende Zukunft öffnet
Tracheal Resection after Previous Treatment Provides Comparable Outcome to Primary Surgery
Authors: Slama Alexis , Zaatar Mohamed , Demir Muhittin , Okumus Oezlem , Mattheis Stefan , Kampe Sandra , Darwiche Kaid , Lang Stephan , Aigner Clemens
Published: June 2021

Background Tracheal and laryngotracheal surgery provides both excellent functional results and long-term outcomes in the treatment of tracheal stenosis. Consequently, challenging re-resections are rarely necessary. The purpose of this study was to compare the outcome of (laryngo-)tracheal re-resection and surgery after bronchoscopic interventions with that of primary surgery.

Methods Patients undergoing resection for benign tracheal stenosis at our center between 1/2016 and 4/2020 were included. Perioperative characteristics and functional outcomes of patients were used for statistical analysis.

Results Sixty-six patients who underwent (laryngo-)tracheal resection were included (previous resection [A = 6], previous stent [B = 6], previous bronchoscopic intervention w/o stenting [C = 19], untreated [D = 35]). Baseline parameters were largely comparable between groups with exception from group B that had significantly worse lung function. Group A necessitated more complex reconstructions (end-to-end: n = 1: 17%| cricotracheal n = 2: 33%| cricotracheal with mucosectomy n = 2: 33%| laryngoplasty: n = 1: 17%) than patients in group D (end-to-end n = 21: 60%| cricotracheal n = 14: 40%). Postoperative outcomes were comparable throughout groups (intensive care unit: 1[1–18] days; hospital stay: 8[5–71] days). Anastomotic complications were higher after previous stenting (A: 0%; B: 33.3%; C: 10.5%; D: 2.9%; B/D p = 0.008| surgical revisions: A: 16.7%; B: 33.3%; C: 0%; D: 5.7%; B/D, p = 0.035). Overall, postoperative lung function was significantly better (forced expiratory volume in 1 second: 63% ± 24 vs. 75% ± 20; p = 0.001 | PeakEF 3.3 ± 1.9 vs. 5.0 ± 2.2L; p = 0.001). No 90-day mortality was observed in any group. Median follow-up was 12(1–47) months.

Conclusion In carefully selected patients treated in a specialized center, tracheal or laryngotracheal resection after previous tracheal interventions provides comparable outcome to primary surgery.
Management of Visceral Artery Pseudoaneurysms by Combined Technique of Percutaneous Thrombin Injection and Endovascular Coiling
Authors: Sivalingam Kalpana , Palanisamy Karthik , Ignatius Amalan
Published: June 2021

Purpose To describe our initial experience with percutaneous thrombin injection combined with endovascular coiling of high-flow visceral artery pseudoaneurysms.

Materials and Methods Institutional review board approval was obtained. Between January 2019 and February 2020, 21 patients with nonvariceal upper gastrointestinal (GI) bleed underwent multidetector CT angiography. Four patients with acute pancreatitis and large pseudoaneurysms were selected for the combined technique. Human thrombin reconstituted with calcium chloride was injected percutaneously. Partially thrombosed aneurysms were treated up to three times. Simultaneously or within 15 days, coil embolization of the neck or patent part of pseudoaneurysm was performed. Patients were followed up to 1 month postprocedure.

Results The size of the pseudoaneurysms ranged from 3 cm to 6 cm. All were accessed percutaneously by 22G Chiba needle under ultrasound guidance and 500 to 1500 units of thrombin was injected in one to three attempts. Subsequently, endovascular coiling of the neck of the pseudoaneurysm or of the feeding artery was performed. Technical success with cessation of flow was achieved in all four patients. One patient developed obstructive jaundice postprocedure and another continued to have GI bleeding despite thrombin injection.

Conclusion Percutaneous thrombin injection is an easy to use and effective tool for treating visceral artery pseudoaneurysms and can be combined with endovascular coiling for successful occlusion of large pseudoaneurysms.
Outcomes of Endovascular Therapy for Salvage of Hemodialysis Arteriovenous Fistulae
Authors: Yadav Nishtha , Gamanagatti Shivanand , Sharma Raju , Aggarwal Sanjay Kumar , Bansal V. K. , Kandasamy Devasenathipathy , Seenu V.
Published: June 2021

Introduction Arteriovenous fistulae (AVF) for hemodialysis (HD) are prone to development of multiple complications, which can lead to nonfunctioning of the fistula. We report outcomes of endovascular management for dysfunctional HD AVF.

Materials and Methods In this prospective study, patients (43 men, 28 women, mean age 47.4 years) with clinical signs and symptoms of dysfunctional HD AVF and referred to interventional radiology for endovascular management were included. The most common clinical presentation included low flows during hemodialysis (n = 20), absent flow (n = 37), and failure of fistula maturation (n = 14). Patients with central venous obstruction who presented with limb swelling were excluded from this study. Patients underwent venography, venoplasty and thrombectomy, as appropriate, to salvage the fistula. The study outcomes were technical success, hemodynamic success, and clinical success of endovascular therapies in salvaging the fistulae.

Results The technical, hemodynamic and clinical success rates of endovascular therapy for low-flow symptoms were 95%, 70% and 95%, respectively. Among patients who presented with absent flow, endovascular therapy had 81% technical success, 78.3% hemodynamic success, and 81% clinical success. Endovascular therapy was associated with 64.2% technical success, 57.1% hemodynamic success, and 64.2% clinical success in patients presenting with failed maturation of the fistula. The overall clinical success rate was 58/71 (81.7%) and failure rate was 13/71 (18.3%). The overall complication rate of endovascular therapy was 8.4% and the complications included vein rupture in 5 (7%) and balloon rupture in 1 (1.4%).

Conclusion Endovascular therapy for salvage of nonfunctioning hemodialysis AVF is associated with a high-clinical success rate (81.7%) and low-complication rate.
Modeling the vapor-liquid equilibrium with computer simulations
Authors: McConnon Aili
Published: June 2021

Combining the advanced MB-pol water model with a widely used molecular simulation software allows researchers to better understand how liquid transforms into water vapor and vice versa.
Breaking the symmetry of sound propagation
Authors: Lim Alane
Published: June 2021

The physics of acoustic nonreciprocity – the notion hearing sound does not have to be equal on both sides.
Characterization and visible light photocatalytic activity of cucurbit[n]urils/CdS-MoS2
Authors: Shi Juan-juan , Zhao An-ting , Peng Zhang-mei , Yang Li-xia , Zhou Chun-tao
Published: June 2021

In order to reduce the impact of CdS photogenerated electron-hole recombination on its photocatalytic performance, a narrow band gap semiconductor MoS2 and organic macromolecular cucurbit[n]urils (Q[n]) were used to modify CdS. Q[n]/CdS-MoS2 (n=6, 7, 8) composite photocatalysts were synthesized by hydrothermal method. Infrared spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, field emission scanning electron microscopy, ultraviolet-visible and photoluminescence spectrum were used to characterize the structure, morphology and optical properties of the products, and the catalytic degradation of the solutions of methylene blue, rhodamine B and crystal violet by Q[n]/CdS-MoS2 composite catalyst was investigated. The results showed that the Q[n] played a regulatory role on the growth and crystallization of CdS-MoS2 particles, Q[n]/CdS-MoS2 (n=6, 7, 8) formed flower clusters with petal-like leaves, the flower clusters of petal-like leaves increased the surface area and active sites of the catalyst, the Q[n]/CdS-MoS2 barrier width decreased, the electron-hole pair separation efficiency was improved in the Q[6]/Cds-MoS2. Q[n] makes the electron-hole pair to obtain better separation and migration. The Q[6]/CdS-MoS2 and Q[7]/CdS-MoS2 have good photocatalytic activity for methylene blue, and the catalytic process is based on hydroxyl radical principle.
Amorphous Fe nanoclusters embedded inside balloon-like N-doped hollow carbon for efficient electrocatalytic oxygen reduction
Authors: Liu Ling-yun , Li Yue , Zi Zhen-fa , Li Ren-wen , Meng Ying , Wu Yao-dong , Wei Xin , Ma Yuan
Published: June 2021

Rational designs of electrocatalytic active sites and architectures are of great importance to develop cost-efficient non-noble metal electrocatalysts towards efficient oxygen reduction reaction (ORR) for high-performance energy conversion and storage devices. In this work, active amorphous Fe-based nanoclusters (Fe NC) are elaborately embedded at the inner surface of balloonlike N-doped hollow carbon (Fe NC/Ch sphere) as an efficient ORR electrocatalyst with an ultrathin wall of about 10 nm. When evaluated for electrochemical performance, Fe NC/Ch sphere exhibits decent ORR activity with a diffusion-limited current density of ∼5.0 mA/cm2 and a half-wave potential of ∼0.81 V in alkaline solution, which is comparable with commercial Pt/C and superior to Fe nanoparticles supported on carbon sheet (Fe NP/C sheet) counterpart. The electrochemical analyses combined with electronic structure characterizations reveal that robust Fe−N interactions in amorphous Fe nanoclusters are helpful for the adsorption of surface oxygen-relative species, and the strong support effect of N-doped hollow carbon is benefitial for accelerating the interfacial electron transfer, which jointly contributes to improve ORR kinetics for Fe NC/Ch sphere.
Surface synergistic protections on red phosphorus anode material by poly(3,4-ethylenedioxythiophene) coating and electrolyte strategy in sodium ion batteries
Authors: Liu Yong-chao , Wu Qiu-jie , Wu Long-jun , Sun Yi , Liang Xin , Xiang Hong-fa
Published: June 2021

Red phosphorus has attracted more attention as a promising sodium storage material due to its ultra-high theoretical capacity and suitable sodiation potential. However, the low intrinsic electrical conductivity and large volume change of pristine red phosphorus lead to high polarization and fast capacity fading during cycling. Herein, surface synergistic protections on red phosphorus composite are successfully proposed by conductive poly(3,4-ethylenedioxythiophene) (PEDOT) coating and electrolyte strategy. Nanoscale red phosphorus is confined in porous carbon skeleton and the outside is packaged by PEDOT coating via in-situ polymerization. Porous carbon provides rich pathways for rapid Na+ diffusion and empty spaces accommodate the volume expansion of red phosphorus, PEDOT coating isolates the direct contact between electrolyte and active materials to form a stable solid electrolyte interphase. In addition, the reformulated electrolyte with 3 wt% SbF3 additives can stabilize the electrode surface and thus enhance the electrochemical performance, especially cycling stability and rate capability (433 mA·h·g−1 at high current density of 10 A/g).
Detailed diffraction imaging of x-ray optics crystals with synchrotron radiation
Authors: Pereira N. R. , Macrander A. T. , Kasman E. , Huang X.-R. , Baronova E. O.
Published: June 2021

Rocking curve topography at the Advanced Photon Source’s beamline 1-BM measures the x-ray reflection from large (many cm2) flat crystals on a sub-mm scale with microradian angular resolution. The (011̄1) reflection at 8 keV is uniform across the crystal and close to theory for three thick quartz wafers well-polished with increasingly finer grit. However, the reflection is non-uniform for some ∼0.1 mm thin, bendable crystals that are made flat by optical contact with a flat substrate. These thin crystals are bent to serve in certain x-ray diagnostics of plasmas, and similar non-uniformities could then occur in bent crystals as well. The same detail in x-ray reflection in bent crystals is unachievable with the existing topography setup: One way to get the desired resolution is with a standard microfocusing approach.
Molecular dynamics simulations of ultrafast radiation induced melting at metal–semiconductor interfaces
Authors: Ravichandran Ashwin , Mehta Mohit , Woodworth Andrew A. , Lawson John W.
Published: June 2021

Metal–semiconductor contacts in silicon carbide (SiC) diodes endure damages at the interface when exposed to harsh radiation environments. Due to the rapid rise in temperature and ultrafast cooling that follows the radiation impact, the structural properties of the materials can be altered through melting, recrystallization, and amorphization. A detailed understanding of the material failure modes at the interface is lacking, specifically at the nanoscale. We use molecular simulations to investigate the ultrafast melting at tungsten (W)–SiC interfaces following radiation damage and apply deep learning techniques to track the transient evolution of the local molecular structures. We show that W near the radiation track undergoes melting and, eventually, most of it recrystallizes with a noticeable degree of undercooling, while SiC is rendered permanently amorphous. The observation of local undercooling in W films is important as it can affect the device performance even before the bulk melting temperature of the material is reached. We also show that at high temperatures, the interface undergoes a fracture-like failure. The results presented here are significant in understating the different failure modes of SiC diode materials.
High-fidelity kinetic modeling of instabilities and gyromotion physics in nonuniform low-beta plasmas
Authors: Vogman G. V. , Hammer J. H.
Published: June 2021

A fourth-order accurate continuum kinetic Vlasov solver and a systematic method for constructing customizable kinetic equilibria are demonstrated to be powerful tools for the study of nonuniform collisionless low-beta plasmas. The noise-free methodology is applied to investigate two gradient-driven instabilities in 4D (x,y,vx,vy) phase space: the Kelvin–Helmholtz instability and the lower hybrid drift instability. Nonuniform two-species configurations where ion gyroradii are comparable to gradient scale lengths are explored. The approach sheds light on the evolution of the pressure tensor in Kelvin–Helmholtz instabilities and demonstrates that the associated stress tensor deviates significantly from the gyroviscous stress tensor. Even at high magnetization, first-order approximations to finite-gyromotion physics are shown to be inadequate for the Kelvin–Helmholtz instability, as shear scales evolve to become on par with gyromotion scales. The methodology facilitates exploring transport and energy partitioning properties associated with lower hybrid drift instabilities in low-beta plasma configurations. Distribution function features are captured in detail, including the formation of local extrema in the vicinity of particle-wave resonances. The approach enables detailed targeted investigations and advances kinetic simulation capability for plasmas in which gyromotion plays an important role.
Neoclassical transport simulations with an improved model collision operator
Authors: Matsuoka S. , Sugama H. , Idomura Y.
Published: June 2021

The improved model collision operator proposed by Sugama et al. [Phys. Plasmas 26, 102108 (2019)], in which the original Sugama collision operator [Phys. Plasmas 16, 112503 (2009)] is extended to recover the friction–flow relation of the linearized Landau (exact) collision operator, is newly implemented in a global full-f gyrokinetic simulation code, GT5D. Neoclassical transport simulations of a single ion species plasma in a circular concentric tokamak are performed over the wide collisionality regime. The improved operator is verified to reproduce the neoclassical thermal diffusivity of Braginskii precisely in the Pfirsch–Schlüter regime, where a friction–flow relation of higher accuracy is required than in the lower collisional regime. In addition, it is found in all collisionality regimes that the overestimation of the neoclassical thermal diffusivity and the magnitude of the parallel flow coefficient observed for the original Sugama operator can be eliminated by using the improved operator, demonstrating that collisional processes described by the exact operator are correctly retained in the improved operator.
Model protein excited states: MRCI calculations with large active spaces vs CC2 method
Authors: Brenner Valérie , Véry Thibaut , Schmidt Michael W. , Gordon Mark S. , Hoyau Sophie , Ben Amor Nadia
Published: June 2021

Benchmarking calculations on excited states of models of phenylalanine protein chains are presented to assess the ability of alternative methods to the standard and most commonly used multiconfigurational wave function-based method, the complete active space self-consistent field (CASSCF), in recovering the non-dynamical correlation for systems that become not affordable by the CASSCF. The exploration of larger active spaces beyond the CASSCF limit is benchmarked through three strategies based on the reduction in the number of determinants: the restricted active space self-consistent field, the generalized active space self-consistent field (GASSCF), and the occupation-restricted multiple active space (ORMAS) schemes. The remaining dynamic correlation effects are then added by the complete active space second-order perturbation theory and by the multireference difference dedicated configuration interaction methods. In parallel, the approximate second-order coupled cluster (CC2), already proven to be successful for small building blocks of model proteins in one of our previous works [Ben Amor et al., J. Chem. Phys. 148, 184105 (2018)], is investigated to assess its performances for larger systems. Among the different alternative strategies to CASSCF, our results highlight the greatest efficiency of the GASSCF and ORMAS schemes in the systematic reduction of the configuration interaction expansion without loss of accuracy in both nature and excitation energies of both singlet ππ* and nπ*CO excited states with respect to the equivalent CASSCF calculations. Guidelines for an optimum applicability of this scheme to systems requiring active spaces beyond the complete active space limit are then proposed. Finally, the extension of the CC2 method to such large systems without loss of accuracy is demonstrated, highlighting the great potential of this method to treat accurately excited states, mainly single reference, of very large systems.
Spiral streamline pattern around a critical point: Its dual directivity and effective characterization by right eigen representation
Authors: Zou Wennan , Xu Xiangyang , Tang Changxin
Published: June 2021

In recent years, vortex recognition method based on velocity gradient has rapidly become a research hotspot, accompanied by a wide range of applications. As a linear velocity field with the origin as its critical point uniquely corresponds to the velocity gradient, its streamline pattern (SP), especially the spiral streamline structure when the velocity gradient has a couple of complex eigenvalues, is studied using the right eigen representation based on the real Schur form. Compared with the left eigen representation, the right eigen representation of velocity gradient is seldom concerned. In this paper, the right eigen representation is carried out in terms of the spectral representation, and its relation with the left eigen representation is also derived. For two-dimensional case, the SP classification is listed and the typical streamlines are illustrated. After detailed investigation, it is shown that the parameters extracted from the right eigen representation would be more suitable to describe the geometrical features of the spiral streamline pattern around the critical point, and the dual directivity of spiral streamline structure is clarified. Some discussions and an illustrative example from the direct numerical simulation (DNS) data are presented.
Response of turbulent pipe flow to targeted wall shapes at a range of Reynolds numbers
Authors: Masoumifar Mehran , Verma Suyash , Hemmati Arman
Published: June 2021

The response and recovery of turbulent pipe flow to three-dimensional perturbed wall changes were examined numerically in a wide range of Reynolds numbers between Re=5×103 and 1.58×105. The perturbations were based on distinct azimuthal Fourier modes corresponding to m = 3, 15, and 3 + 15. The long-lasting response of the flow was examined by characterizing both the mean and turbulent field in the wake of pipe inserts for each Re. The variation of the recovery with increasing Reynolds number revealed an asymptotic behavior for Re≥7.5×104, which scaled with Re4 for both mean velocity and turbulence kinetic energy. Two peaks were observed for the mean velocity along the wake centerline, where the location of peaks followed a power-law trend in the form of Lp/D∝Re4/3, where D is the pipe diameter. A fast decay of turbulence past the wall change further suggested that maximum Reynolds shear stress in the downstream wake decays as (x/D)−1/3 for all Re. The flow also exhibited long-lasting responses that obstructed its relaxation at 20D downstream of the perturbation, even for low Re of 5×103. Overall, the recovery exhibited a second-order response.
Dynamics of the cavity evolution during vertical water entry of deformable spheres
Authors: Yang Liu , Wei Yingjie , Wang Cong , Xia Weixue , Li Jiachuan , Wang Zilu , Zhang Dehua
Published: June 2021

Despite cavity dynamics have been studied for more than a century, cavity formations during water entry of deformable spheres have rarely been studied. Series of interesting cavities arise during vertical water entry of deformable spheres. We study these phenomena experimentally and numerically. Experimental observations show that deformable spheres can produce three typical cavities: dumpy cavity, tight cavity, and nested cavity. Numerical modeling accounts for the effect of elasticity on the cavity dynamics. Our results show that the motion parameters used to characterize the three typical cavity walls present a hierarchical order. During the first cycle of cavity flows, the dependence of the dynamics of the deformed sphere on the dimensionless ratio of material shear modulus to impact hydrodynamic pressure is determined. Before the pinch-off of cavity, a density correction coefficient is proposed to characterize the linearization of wetted areas. Elasticity can alter the shape of the cavity, which requires sufficient impact conditions and material properties. Within this range, the formation time and number of the nested cavity are analyzed. On this basis, the minimum velocity required to form the nested cavity is theoretically predicted and identified by experimental and numerical techniques.
Simulations of the shock-driven Kelvin–Helmholtz instability in inclined gas curtains
Authors: Romero Brian , Poroseva Svetlana V. , Vorobieff Peter , Reisner Jon M.
Published: June 2021

In this paper, we present simulation results for the two-dimensional, shock-driven Kelvin–Helmholtz instability. Simulations are performed with a Mach 2.0 shock propagating through a finite-thickness curtain of gas inclined at an angle α0=30° with respect to the shock plane. After the passage of the shock, the gas curtain is accelerated along its axis. A perturbation develops due to shock reflection near the lower wall, and a Kelvin–Helmholtz instability forms near the vertical center of the curtain. This is the first known numerical reproduction of these phenomena that have previously been observed in experiments with an inclined cylindrical gas column. The effects of varying Mach number and column width were explored in detail to complement experimental data. The dependence of the Kelvin–Helmholtz wavelength on Mach number closely matches the relationship observed in experiments. This supports the notion that the observed instability is effectively two-dimensional and inviscid (like classical Kelvin–Helmholtz). The growth rate of the perturbations in the gas curtain was also found to be similar for different Mach numbers. The perturbation at the curtain foot, previously unreported in experiments, was found to have a similar relationship to Mach number as the Kelvin–Helmholtz instability. Both perturbation wavelengths are found to be proportional to layer width. Simulations were performed with the fast interfaces and transport in the atmosphere, an exascale ready, graphics processing unit-accelerated compressible flow solver developed at the University of New Mexico.
Lab-on-a-chip based mechanical actuators and sensors for single-cell and organoid culture studies
Authors: Männik Jaan , Teshima Tetsuhiko F. , Wolfrum Bernhard , Yang Da
Published: June 2021

All living cells constantly experience and respond to mechanical stresses. The molecular networks that activate in cells in response to mechanical stimuli are yet not well-understood. Our limited knowledge stems partially from the lack of available tools that are capable of exerting controlled mechanical stress to individual cells and at the same time observing their responses at subcellular to molecular resolution. Several tools such as rheology setups, micropipetes, and magnetic tweezers have been used in the past. While allowing to quantify short-time viscoelastic responses, these setups are not suitable for long-term observations of cells and most of them have low throughput. In this Perspective, we discuss lab-on-a-chip platforms that have the potential to overcome these limitations. Our focus is on devices that apply shear, compressive, tensile, and confinement derived stresses to single cells and organoid cultures. We compare different design strategies for these devices and highlight their advantages, drawbacks, and future potential. While the majority of these devices are used for fundamental research, some of them have potential applications in medical diagnostics and these applications are also discussed.
Discovery of polymer electret material via de novo molecule generation and functional group enrichment analysis
Authors: Zhang Yucheng , Zhang Jinzhe , Suzuki Kuniko , Sumita Masato , Terayama Kei , Li Jiawen , Mao Zetian , Tsuda Koji , Suzuki Yuji
Published: June 2021

We designed a high-performance polymer electret material using a deep-learning-based de novo molecule generator. By statistically analyzing the enrichment of the functional groups of the generated molecules, the hydroxyl group was determined to be crucial for enhancing the electron gain energy. Incorporating such acquired knowledge, we designed a molecule using cyclic transparent optical polymer (CYTOP; perfluoro-3-butenyl-vinyl ether). The molecule was synthesized, and its surface potential for a 15-μm-thick film is kept at −3 kV for more than 800 h. Its performance was significantly better than all commercialized CYTOP polymer electrets, indicating great potential for its application in vibration-based energy harvesting. Our results demonstrate the application of machine learning in polymer electret design and confirm the combination of molecule generation and functional group enrichment analysis to be a promising chemical discovery method achieved via human–artificial intelligence collaboration.
A high-efficiency smoothed particle hydrodynamics model with multi-cell linked list and adaptive particle refinement for two-phase flows
Authors: Zhao Zhen-Xi , Liu Hua , Gong Zhao-Xin
Published: June 2021

The smoothed particle hydrodynamics method has been applied in modeling violent flows with the free surface. Much effort has been made in reducing the computational costs in simulating the three-dimensional two-phase flows with the violently deformed free surface and breaking waves. Although the adaptive particle refinement approach has been developed to concentrate fine resolution only in the region of interest, its efficiency still hardly meets the demand of large-scale numerical simulation. In order to improve its efficiency further, a multi-cell linked list algorithm coupling with the adaptive particle refinement for the smoothed particle hydrodynamics model is implemented in the graphic processing unit-based code. Particles are identified not only by its position but also by its resolution and trait. The accuracy of the numerical model for solving two-phase flows with the free surface is validated through computing a two-dimensional dam-break flow and the hydrodynamic flows of spheres vertically entering the water from the air. The numerical results agree well with the experimental data available. For the cases of water entry of a sphere of different densities, the development of open cavity and cavity sealing is discussed in terms of the pinch-off depth and the corresponding sphere depth. Simulations show that the smoothed particle hydrodynamics method with the adaptive particle refinement possesses the characteristics of good accuracy, time-saving, and high efficiency in simulating three-dimensional two-phase flows.
[Ni8(CNtBu)12][Cl]: A nickel isocyanide nanocluster with a folded nanosheet structure
Authors: Touchton Alexander J. , Wu Guang , Hayton Trevor W.
Published: June 2021

The reaction of 1.75 equiv of tBuNC with Ni(1,5-COD)2, followed by crystallization from benzene/pentane, resulted in the isolation of [Ni8(CNtBu)12][Cl] (2) in low yields. Similarly, the reaction of Ni(1,5-COD)2 with 0.6 equiv of [Ni(CNtBu)4], followed by addition of 0.08 equiv of I2, resulted in the formation of [Ni8(CNtBu)12][I] (3), which could be isolated in 52% yield after work-up. Both 2 and 3 adopt folded nanosheet structures in the solid state, characterized by two symmetry-related planar Ni4 arrays, six terminally bound tBuNC ligands, and six tBuNC ligands that adopt bridging coordination modes. The metrical parameters of the six bridging tBuNC ligands suggest that they have been reduced to their [tBuNC]2− form. In contrast to the nanosheet structures observed for 2 and 3, gas phase Ni8 is predicted to feature a compact bisdisphenoid ground state structure. The strikingly different structural outcomes reveal the profound structural changes that can occur upon addition of ligands to bare metal clusters. Ultimately, the characterization of 2 and 3 will enable more accurate structural predictions of ligand-protected nanoclusters in the future.
Optics and neural adaptation jointly limit human stereovision
Authors: Ng Cherlyn J. , Blake Randolph , Banks Martin S. , Tadin Duje , Yoon Geunyoung
Published: June 2021

Significance

Humans, and other animals, have eyes laterally displaced on the head that view the world from slightly different vantage points to create small differences in the left and right images. These differences are utilized for depth perception (stereovision). Retinal images are also subject to optical imperfections, often different in the two eyes. Using advanced optical techniques, we show that even the smallest imperfections escaping clinical detection affect stereovision. Our data also suggest that neural processes become acclimated to a person’s own optics. Hence, stereovision is directly affected by the eyes’ optics and indirectly via neural adaptation. Because the optics change over the lifespan, the implication is that the adult binocular system is adaptable, pointing to the potential for binocular rehabilitation.
Periscope Proteins are variable-length regulators of bacterial cell surface interactions
Authors: Whelan Fiona , Lafita Aleix , Gilburt James , Dégut Clément , Griffiths Samuel C. , Jenkins Huw T. , St John Alexander N. , Paci Emanuele , Moir James W. B. , Plevin Michael J. , Baumann Christoph G. , Bateman Alex , Potts Jennifer R.
Published: June 2021

Significance

The structure of single and tandem SHIRT domains from the streptococcal surface protein Sgo_0707 were determined. In conjunction with biophysics and molecular dynamics simulations, the results show that the observed gene length variation would result in differential projection of the host ligand binding domain on the bacterial cell surface. An analysis of long-read DNA sequence data reveals many other repetitive bacterial surface proteins that appear to undergo gene length variation. We propose that these variable-length “Periscope Proteins” represent an important mechanism of bacterial cell surface modification with potential roles in infection and immune evasion.
Characterizing the “fungal shunt”: Parasitic fungi on diatoms affect carbon flow and bacterial communities in aquatic microbial food webs
Authors: Klawonn Isabell , Van den Wyngaert Silke , Parada Alma E. , Arandia-Gorostidi Nestor , Whitehouse Martin J. , Grossart Hans-Peter , Dekas Anne E.
Published: June 2021

Significance

Planktonic microorganisms interact with each other in multifarious ways, ultimately catalyzing the flow of carbon and energy in diverse aquatic environments. However, crucial links associated with eukaryotic microparasites are still overlooked in planktonic networks. We addressed such links by studying cryptic interactions between parasitic fungi, phytoplankton, and bacteria using a model pathosystem. Our results demonstrate that parasitic fungi profoundly modified microbial interactions through several mechanisms (e.g., transferring photosynthetic carbon to infecting fungi, stimulating bacterial colonization on phytoplankton cells, and altering the community composition of bacteria and their acquisition of photosynthetic carbon). Hence, fungal microparasites can substantially shape the microbially mediated carbon flow at the base of aquatic food webs and should be considered as crucial members within plankton communities.
Liquid crystal display screens as a source for indoor volatile organic compounds
Authors: Liu Qifan , Abbatt Jonathan P. D.
Published: June 2021

Significance

Liquid crystal displays (LCDs), ubiquitously used indoors in smartphones, computer monitors, laptops, and televisions, have become an essential aspect of modern life. We find LCD screens can emit significant levels of volatile organic compounds (VOCs), an important class of indoor air constituents with known adverse health effects. These screen-emitted VOCs are likely derived from the “building block chemicals” used in the manufacturing of liquid crystals. The results indicate that LCD screens are a previously unrecognized source for indoor VOCs, highlighting the need to better understand the environmental fate and toxicological properties associated with the air constituents emitted from LCD screens.
Armillaria limonea.
Authors: Hood Ian , Shaw Charles
Published: June 2021

Armillaria limonea is a white rot wood decay fungus and root disease pathogen that has confirmed presence in New Zealand only, where it is presumed to be indigenous. It is closely related to A. luteobubalina in Australia and South America, and to South American A. montagnei. A. limonea occurs naturally on woody debris and as a cause of butt rot in living trees in podocarp-hardwood and southern beech (Nothofagus) forests where it contributes beneficially to carbon and nutrient recycling. It fruits prolifically in native forests, forming large clusters of "toadstool" fruitbodies during winter. Like many other Armillaria species it is recognized by characteristic white mycelial fans or ribbons produced beneath host bark, and by its bootlace-like rhizomorphs by which it spreads vegetatively from colonized buried woody material or stump root systems to infect living host plants.
Coniothyrium glycines (red leaf blotch).
Authors: Hartman Glen , Murithi Harun Muthuri
Published: June 2021

Red leaf blotch affects soyabean in central and southern Africa. The disease and the causal fungus (Coniothyrium glycines) were first reported in Ethiopia in 1957. C. glycines is native to Africa, living on the native legume, Neonotonia wightii, and perhaps other native or non-native legumes. The jump of the pathogen to soyabean occurred as early as 1957 and reports of the occurrence of red leaf blotch have increased along with soyabean production in Africa. The disease is currently a serious threat to soyabean production in sub-Saharan African countries with losses of up to 70% reported. C. glycines is considered a threat to soyabean-producing countries such as Brazil and the USA. The pathogen is not known to be disseminated by seed or wind. Infection is thought to occur via rainsplash of soilborne inoculum onto the leaves of soyabean plants. Symptoms include characteristic dark red spots on the upper leaf surface and reddish-brown lesions with dark borders on the lower surface. Premature leaf drop may occur in heavy disease conditions, releasing sclerotia back into the soil. The disease is favoured by wet, humid conditions.
Candidatus Phytoplasma australiense.
Authors: Liefting Lia
Published: June 2021

Phytoplasmas are wall-less, phloem-limited unculturable bacteria that are naturally spread by sap-sucking insects. 'Candidatus Phytoplasma australiense', subgroup 16SrXII-B, is associated with a wide range of diseases in Australia and New Zealand. Important commercial crop hosts of 'Ca. Phytoplasma australiense' include grapevine, papaya and strawberry. This phytoplasma is associated with rapid death of its papaya and cabbage tree hosts. In New Zealand, the insect vectors have been confirmed to be the endemic Cixiid planthoppers, Zeoliarus atkinsoni and Z. oppositus, while in Australia no vector has yet been determined, although the leafhopper, Orosius argentatus, has been implicated. Long distance spread of the phytoplasma is possible through infected vegetative propagating material. 'Ca. Phytoplasma australiense' is on the A1 list of regulated organisms for Canada and Bahrain, and is listed as a quarantine pest for the USA.
Peronosclerospora philippinensis (Philippine downy mildew of maize).
Authors: dela Cueva Fe M. , de Castro Alyssa M. , de Torres Rachele L.
Published: June 2021

Peronosclerospora philippinensis, a causal pathogen of maize downy mildews, is one of the major maize diseases reported in some maize-growing countries, especially in the Philippines. High disease incidence has been reported in many parts in the country specifically in northern Luzon and in many parts of Mindanao despite breakthroughs in controlling or mitigating the disease using cultural and chemical control (Pascual et al., 2005). P. philippinensis is considered the most virulent of the downy mildew pathogens affecting maize, causing substantial losses to crop production (Murray, 2009). Under normal conditions, a 40-60% yield reduction is observed; however, favourable conditions for disease development can amplify these losses to 80-100% (Exconde and Raymundo, 1974). As the pathogen is able to survive in seeds, is able to spread rapidly and occasionally forms resting spores that can survive for more than 1 year, the pathogen has the potential to become a threat to local maize production in warm temperate and tropical areas.
Pseudomonas cichorii (bacterial blight of endive).
Authors: Osdaghi Ebrahim
Published: June 2021

Under environmental conditions favourable to the pathogen, diseases incited by P. cichorii cause severe damage to the host and can result in outbreaks. Outbreaks in the nursery or in the field during warm winters in Florida, USA, can lead to widespread disease affecting thousands of plants (Jones et al., 1983; Chase and Brunk, 1984; Uddin and McCarter, 1996). Diseases caused by P. cichorii can appear sporadically over a number of years then cause severe outbreaks such as the outbreak of 'varnish spot of lettuce' in California (Grogan et al. 1977) and 'brown stem of celery' in Florida, USA (Pernezny et al., 1994). Severe disease outbreaks on lettuce leading to losses of up to 100% have been reported in California (Grogan et al., 1977), Italy (Bazzi and Mazzucchi, 1979) and Portugal (Ferreira-Pinto and Oliveira, 1993). In Italy and France, P. cichorii is a recurring problem on endive and lettuce (Allex and Rat 1990; D'Ascenzo et al., 1997). In Florida, brown stem of chrysanthemum only occurs about every 5 to 6 years whereas leaf spot occurs annually (Pernezny et al., 1994).