bluuebunny/crossref_metadata_2025 huggingface dataset:
Discharge of a granular silo under mechanical vibrations
Authors: Pascot Arthur , Marouazi Ghita , Kiesgen De Richter Sébastien
Published: June 2021

In this paper, we study the flow rate of model granular material in a silo under the influence of mechanical vibrations. Experimental measurements and discrete element simulations (DEM) are performed in a quasi-2D silo. The influence on the flow rate of the opening size and the vibration applied on the entire silo is studied. Two distinct regimes are evidenced, governed by the Froude numberFrand the relative frequency Ω. In the first regime, a decreased flow rate is observed when increasing the vibration intensity. This behavior is explained by the presence of reorganizations induced by the vibration, leading to a more homogeneous but also slower flow. In the second regime, an increased flow rate is evidenced when increasing the vibration intensity. We find this behavior comes from the intermittent nature of the flow, where the flow rate is directly controlled by the propagation of shock waves all along the silo.
Stability of the homogeneous steady state for a model of a confined quasi-two-dimensional granular fluid
Authors: Garzó Vicente , Brito Ricardo , Soto Rodrigo
Published: June 2021

A linear stability analysis of the hydrodynamic equations of a model for confined quasi-two-dimensional granular gases is carried out. The stability analysis is performed around the homogeneous steady state (HSS) reached eventually by the system after a transient regime. In contrast to previous studies (which considered dilute or quasielastic systems), our analysis is based on the results obtained from the inelastic Enskog kinetic equation, which takes into account the (nonlinear) dependence of the transport coefficients and the cooling rate on dissipation and applies to moderate densities. As in earlier studies, the analysis shows that the HSS is linearly stable with respect to long enough wavelength excitations.
Neck growth kinetics during polymer sintering for powder-based processes
Authors: Alvarez Juan E. , Snijder Henk , Vaneker Tom , Cheng Hongyang , Luding Stefan , Weinhart Thomas
Published: June 2021

To prevent texture defects in powder-based processes, the sintering time needs to be adjusted such that a certain amount of coalescence is achieved. However, predicting the required sintering time is extremely challenging to assess in materials such as polymers because the kinetics exhibit both elastic and viscous characteristics when undergoing deformation. The present work introduces a computational approach to model the viscoelastic eﬀect in the sintering of particles. The model contains three stages, three diﬀerent mechanisms driven by adhesive inter-surface forces and surface tension, which describes the non-linear sintering behaviour. Experimental data from the binary coalescence of Polystyrene (PS), Polyamide (PA) 12 and PEEK 450PF particles are employed to calibrate the contact model, as implemented in MercuryDPM, an open-source software package. Using machine learning-based Bayesian calibration, good agreement is obtained between the experimental data and the numerical results. The findings will be used in future studies to predict densification rates in powder-based processes.
Friction-induced heat generation between two particles
Authors: Kisuka Francisco , Wu Chuan-Yu , Hare Colin
Published: June 2021

Friction-induced heat generation, dissipation and the associated rise in temperature are still an intrinsic problem in many fields dealing with granular materials. This work presents preliminary attempts of modelling heat generation and estimating the contact flash temperatures with the use of a theoretical model. To check the robustness of this theoretical model simulations were run in parallel with Finite element method. The maximum contact temperatures obtained from the theoretical model show a good agreement with FEM results. The promising results imply that the simple theoretical model can be used accurately to predict heat generation in granular materials.
Effect of grain shape on the dynamics of granular materials in 2D rotating drum
Authors: Preud’homme Nicolas , Opsomer Eric , Vandewalle Nicolas , Lumay Geoffroy
Published: June 2021

We experimentally investigate the effect of the grain shape on the flow of granular material. The grain shape is modified to highlight the effect of grain circularity on granular flow in a 2D rotating drum. Using a laser cutter, we create particles with decreasing circularity. We observe that the effect of grain shape depends on the rotation speed of the drum. For high rotation speed, granular flow is influenced by the packing’s dilatancy whereas, at low rotation speed, packing fraction seems to influence flowing dynamics. We link these two measurements to grain shape in order to explain its effect on granular flow.
Modelling realistic ballast shape to study the lateral pull behaviour using GPU computing
Authors: Nader François , Pizette Patrick , Govender Nicolin , Wilke Daniel N. , Ferellec Jean-François
Published: June 2021

The use of the Discrete Element Method to model engineering structures implementing granular materials has proven to be an efficient method to response under various behaviour conditions. However, the computational cost of the simulations increases rapidly, as the number of particles and particle shape complexity increases. An affordable solution to render problems computationally tractable is to use graphical processing units (GPU) for computing. Modern GPUs offer up 10496 compute cores, which allows for a greater parallelisation relative to 32-cores offered by high-end Central Processing Unit (CPU) compute. This study outlines the application of BlazeDEM-GPU, using an RTX 2080Ti GPU (4352 cores), to investigate the influence of the modelling of particle shape on the lateral pull behaviour of granular ballast systems used in railway applications. The idea is to validate the model and show the benefits of simulating non-spherical shapes in future large-scale tests. The algorithm, created to generate the shape of the ballast based on real grain scans, and using polyhedral shape approximations of varying degrees of complexity is shown. The particle size is modelled to scale. A preliminary investigation of the effect of the grain shape is conducted, where a sleeper lateral pull test is carried out in a spherical grains sample, and a cubic grains sample. Preliminary results show that elementary polyhedral shape representations (cubic) recreate some of the characteristic responses in the lateral pull test, such as stick/slip phenomena and force chain distributions, which looks promising for future works on railway simulations. These responses that cannot be recreated with simple spherical grains, unless heuristics are added, which requires additional calibration and approximations. The significant reduction in time when using non-spherical grains also implies that larger granular systems can be investigated.
Effect of particle shape on bubble dynamics in bubbling fluidized bed
Authors: Shrestha Siddhartha , Zhou Zongyan
Published: June 2021

Particle shape can significantly affect the bubble dynamics of bubbling fluidized beds (BFB). In this paper, findings obtained from simulations using CFD-DEM are summarized to discuss the effect of particle shape on bubble dynamics and bubble properties such as bubble size, shape and velocity at a single orifice and uniform fluidized bed. Particles with aspect ratios at 0.5 (oblate), 1 (spherical) and 2 (prolate) are employed to represent disc-like, spherical and rod-like particles, respectively. Both single jet and uniform fluidized bed simulations demonstrate that the bubble forming/rising regions, bubble coalescence locations, and bubble splitting phenomena are significantly influenced by particle shape. The CFD-DEM results for bubble size and bubble velocity show good agreement with literature correlations.
A study on the effect of grain morphology on shear strength in granular materials
Authors: Govender Nicolin , Pizette Patrick
Published: June 2021

The Discrete Element Method (DEM) has been successfully used to further understand GM behaviour where experimental means are not possible or limited. However, the vast majority of DEM publications use simplified spheres with rolling friction to account for particle shape, with a few using clumped spheres and super quadratics to better capture grain geometric detail. In this study, we compare the shear strength of packed polyhedral assemblies to spheres with rolling resistance to account for shape. Spheres were found to have the highest shear resistance as the limited rolling friction model could not capture the geometric of rotation grains which caused reordering and dilation. This geometric arrangement causes polyhedra to align faces in the shear direction, reducing the resistance to motion. Conversely, geometric interlocking can cause jamming resulting in a dramatic increase in shear resistance. Particle aspect ratio (elongation and fatness) was found to significantly lower shear resistance, while more uniform aspect ratio’s increased shear resistance with shape non-convexity showing extremes of massive slip or jamming. Thus, while spheres with rolling friction may yield bulk shear strength similar to some polyhedra with a mild aspect ratio, the grain scale effect that leads to compaction and jamming from rotation and interlocking is missed. These results shed light on the complex impact that individual grain shape has on bulk behaviour and its importance.
Multi-scale cohesion force measurements for cemented granular materials
Authors: Farhat Abbas , Luu Li-Hua , Philippe Pierre , Cuéllar Pablo
Published: June 2021

We experimentally investigated cohesion of artificially bonded granular materials made of spherical glass beads cemented by solid paraffin bonds. By means of laboratory tests designed and carried out for investigation at different scales, we measured the tensile yield strength for solid bonds both at the inter-particle micro-scale and cemented samples at the meso-scale. A parametric study has been performed by varying some of the granular material properties (bead diameter, paraffin content as well as the dimension of the sample for the meso-scale tensile tests. We finally propose a discusion on: (i) the relationship between the microscopic and macroscopic cohesion forces relying on classical homogenisation laws ; (ii) the potential impact of size effects based on a simple phenomenological model.
Evolution of the coefficient of lateral earth pressure at rest with interparticle friction: a numerical study
Authors: Nguyen Hoang C
Published: June 2021

The grain-scale nature of evolution of the coefficient of lateral earth pressure at rest (K0) with interparticle friction (µp) is poorly understood. This study aims to use discrete element method simulations of vertical one-dimensional compression on both face centred cubic (FCC) samples and random monodisperse (RM) samples to link K0 and µp, and the results show that K0 increases with reductions in interparticle friction. Although K0 is dependent upon the sample density, patterns of evolutions with strain levels are likely to be unchanged with initial confining pressures. The stress-induced fabric becomes more anisotropic for samples with high values of the interparticle friction. The percentage of particles with a high value of the normal contact force increases with increasing strain levels as the interparticle friction increases in the simulations.
Grid-algorithm improvements for dense suspensions of discrete element particles in finite element fluid simulations
Authors: Mueller Jan , Kyotani Akira , Matuttis Hans-Georg
Published: June 2021

For homogeneous systems like classical fluid dynamics and structural mechanics, finite element method (FEM) grid generation has reached a mature state. On the other hand, for multi-physics-problems like fluids with a high density of immersed particles, many researchers may not even be aware of the types of instabilities which may be triggered by unsuitable meshes. We review common types of grid generation, point out previously unrecognised types of instabilities for particles in fluids as well as remedies to obtain particle-fluid simulations with higher stability and fewer redundant degrees of freedom.
Wet rolling stones: Growth of a granular aggregate under flow
Authors: Jop Pierre , Saingier Guillaume , Sauret Alban
Published: June 2021

Wet granulation processes can be driven from low to high water content. In this study, we consider the model situation of the growth of a single wet aggregate rolling in a dry granular flow inside a rotating drum. We measure the time evolution of its diameter for different grains and liquids, as well as various rotation rates of the drum. Using X-ray tomography, we are able to characterize the internal structure of the granular aggregate at different times during the process. We show that the growth rate of the aggregate can be related to the transport of the liquid inside the granule and the capture of grains. We propose a model to rationalize the maximum size of the aggregate and its growth rate.
Hydraulic transport regimes of grains in a millifluidic confinement
Authors: Dumazer Guillaume , Gagnepain Étienne
Published: June 2021

Granular matter transported by hydraulic conveying behaves under several transport regimes. The techncal challenge is to predict the dilute or dense regime of transport as well as the pressure drop required in order to design properly a granular hydraulic conveying system. We address this problem with a laboratory scale experimental setup able to reproduce the key features of hydraulic conveying of grains. Pressure drop measurements as well as image analysis have been used to characterize a slug transport regime and its crossover towards a moving bed transport regime. A dimensionless characteristic curves diagram has been established and a reasonably good pressure drop prediction with a generic power law is explained in details. This preliminary work has the potential to open perspectives for the design of a predictive tool for pressure drops in hydraulic conveying systems.
A sphere packing model for shear bands in dense soils
Authors: Yanqui Calixtro
Published: June 2021

The rhombic sphere packing can be used to model the biaxial test on granular soils in a very simple way. According to the angle of assemblage, the packing is dilatant or contractive. Correspondingly, overall stresses are transmitted as chains of forces or oblique forces of contact. The connection of the soil stress-strain behaviour and the packing void ratio is achieved by mapping both of the plots. The mapping shows that dense soils are dilatant and loose soils are contractive, separated by the critical state. It also shows that the bifurcation point and the peak strength are features only of dense soils. The band of strain localization is analysed in the elastic regime, and its inclination is found maximizing the intensity of the mobilized stress ratio. The stresses within the shear band are obtained by assuming a partially coaxial packing rotated to reach the full plastic state. The equilibrium of the overall stress at the line of discontinuity reveals a relationship between the peak friction angle and the coefficient of lateral pressure at rest. As long as these parameters are obtained independently of each other, they allow the validation of the theory.
Coordination numbers in natural beach sand
Authors: Wright Vanshan , Ferrick Amy , Manga Michael , Sitar Nicholas
Published: June 2021

Coordination number controls elastic moduli, seismic velocity, and force transmission in sands and is thus a critical factor controlling the resistance of sands to deformation. Previous studies quantified relationships between coordination number, porosity, grain size, sphericity, and effective stress in pluviated or modeled sands. Here, we determine if these relationships hold in naturally-deposited beach sands. We collect samples while preserving their microstructures and use x-ray computed microtomography images to characterize grain properties. Similar to pluviated and modeled sand studies, we find that average coordination numbers and porosities for freshly deposited natural sands are 8.1 ± 2.8 and 0.37 ± 0.01, respectively. The range and standard deviation in coordination numbers of the natural beach sands are, however, significantly higher than observed in pluviated and modeled sand studies. At the same effective stress and porosities, coordination number is linearly proportional to grain surface area except for the smallest and largest grains. Coordination number depends non-linearly on sphericity. We attribute the higher ranges and standard deviations of coordination numbers in the natural sands to its broader grain size distribution, and we propose that the largest grains limit grain rearrangement, which influences spatial distributions of coordination numbers in natural sands.
Evolution of rattling particles in deviatoric shear deformation of granular material
Authors: Luo Lisha , Shen Zhifu , Wang Xudong , Gao Hongmei
Published: June 2021

Granular material such as clean sand in geotechnical engineering is characterized by structured internal deformation pattern and some interesting particle arrangement patterns. This study focuses on the evolution of the fraction of rattling particles in deviator deformation until the critical state. Numerical simulations using the discrete element method reveal the presence of rattling particles (with zero or only one contact with neighbouring particles) even in a very dense packing system. The results show that the initial fraction of rattling particles depends on sample density and particle size distribution. With the increase of deviator strain, the number and volume fractions of rattling particles gradually approach a steady critical state from either a loose or a dense starting point. An effective void ratio, which is calculated by treating rattling particles as voids, can be viewed as new state parameter describing the effective packing density of sands. Besides, the rattling behaviour strongly depends on particle size distribution.
Packing dynamics of powders at high temperature
Authors: Neveu Aurélien , Francqui Filip , Lumay Geoffroy
Published: June 2021

In industrial powder processing, precise control of environmental temperature is difficult especially for large production facilities. A better knowledge of powder behavior modification due to temperature variation will help to improve product quality and consistency. From a fundamental point of view, the effect of temperature on powder flow and packing dynamics is still poorly understood. In particular, because temperature modifies the complex interplay between the different forces acting at the contact between the grains. The packing dynamics of a set of different powders (lactose, cacao and dried milk powder) has been investigated with a tapping experiment. After the filling procedure, the sample is heated and the evolution of the density is measured after each tap. We show that the packing dynamics is drastically influenced even for low temperature changes. Slight increase of temperature affects both the packing kinematics and the packing range characterised by the classical Hausner ratio analysis. Finally, the different physical mechanisms that could explain these modifications are discussed. The results of this preliminary study demonstrate the importance of temperature in powder behaviour and strongly motivate further investigations.
Experiments on rebounding slow impacts under asteroid conditions
Authors: Joeris Kolja , Schönau Laurent , Schmidt Lars , Keulen Matthias , Desai Vrinda , Born Philip , Kollmer Jonathan E.
Published: June 2021

We present a newly developed experiment for the examination of low-speed impacts under asteroid conditions. More specifically, our experimental setup enables us to simulate a very clean milligravity environment under vacuum, in which projectiles are shot at a granular bed at several cm/s. This granular bed consists of irregularly formed basalt particles with different size distributions. The experiment is carried out in the Bremen drop tower in its catapult mode, granting more than 9 s microgravity. Here, we discuss the setup and assess its performance.
Mechanisms of size segregation in granular flows with different ambient fluids
Authors: Cui Kahlil Fredrick , Zhou Gordon G.D. , Jing Lu
Published: June 2021

Particle size segregation is ubiquitous in granular systems with differently sized constituents but is found to diminish in the presence of viscous ambient fluids. We study this inhibiting effect through coupled fluid-particle numerical simulations. It is found that size segregation is indeed slower in the presence of fluid and this effect becomes more significant as fluid viscosity is increased. Direct calculation of segregation forcing terms reveal that the ambient fluids affect segregation in two major ways: buoyant forces reduce contact pressures, while viscous dissipation diminish particle-fluctuation driven kinetic pressures, both of which are necessary in driving large particles up. Surprisingly, the fluid drag in the normal direction is negligible regardless of the fluid viscosity and does not directly affect segregation.
From discrete element simulation data to process insights
Authors: Wilke Daniel N. , Cleary Paul W. , Govender Nicolin
Published: June 2021

Industrial-scale discrete element simulations typically generate Gigabytes of data per time step, which implies that even opening a single file may require 5 - 15 minutes on conventional magnetic storage devices. Data science’s inherent multi-disciplinary nature makes the extraction of useful information challenging, often leading to undiscovered details or new insights. This study explores the potential of statistical learning to identify potential regions of interest for large scale discrete element simulations. We demonstrate that our in-house knowledge discovery and data mining system (KDS) can decompose large datasets into i) regions of potential interest to the analyst, ii) multiple decompositions that highlight different aspects of the data, iii) simplify interpretation of DEM generated data by focusing attention on the interpretation of automatically decomposed regions, and iv) streamline the analysis of raw DEM data by letting the analyst control the number of decomposition and the way the decompositions are performed. Multiple decompositions can be automated in parallel and compressed, enabling agile engagement with the analyst’s processed data. This study focuses on spatial and not temporal inferences.
Hypoxämischer Anfall
Authors: Brisch Rica
Published: June 2021

Wartezeiten zum Lernen nutzen – das ist die Idee der One Minute Wonder. Wir stellen in loser Reihe OMWs zu verschiedenen Themen vor.
Einführung einer Transitionssprechstunde
Authors: Adler Kristin
Published: June 2021

In der Betreuung von Jugendlichen und jungen Erwachsenen mit angeborenen Herzfehlbildungen ist der Übergang von der Kinder- und Jugendmedizin in die Erwachsenenmedizin im Alter zwischen 16 und 21 Jahren eine besondere Herausforderung für die Betroffenen und ihre Eltern. Diese Transition ist die Zeit, in der die Jugendlichen den Schritt ins Erwachsenwerden und damit den Schritt zur Übernahme von mehr Verantwortung gehen müssen.
A Retrospective Cross-Sectional Study of the Utility of Cartridge-Based Nucleic Acid Amplification Test in Diagnosis of Pulmonary and Extrapulmonary Tuberculosis in People Living with HIV in Second Highest HIV Prevalent State in India
Authors: Bagbi Tade , Reema Ningthoukhongjam , Devi S. Bhagyabati , Singh Thangjam Gautam , Jaleel Mohammad , Nishad Ravi
Published: June 2021

Introduction Tuberculosis (TB) in people living with human immunodeficiency virus (PLHIV) is difficult to diagnose due to fewer organisms in sputum and extrapulmonary samples. Sputum culture takes 4 to 8 weeks for growth of the mycobacteria. Delayed treatment for TB in PLHIV leads to increased mortality. This study evaluated cartridge-based nucleic acid amplification test (CBNAAT) as a diagnostic tool for diagnosis of pulmonary TB (PTB) and extrapulmonary TB (EPTB) in PLHIV in the second most HIV prevalent state in India and for comparing its efficacy between Ziehl–Neelsen (ZN) staining sputum smear–positive and sputum smear–negative TB.

Methods This cross-sectional study was conducted in RIMS, Imphal, with 167 PLHIV patients, age 15 years or older, having signs and symptoms of TB. Appropriate samples for sputum microscopy and CBNAAT were sent.

Conclusion The overall sensitivity of sputum smear for acid-fast bacillus (AFB) was found to be 30.71% and that of CBNAAT was 38.57%. Sensitivity of CBNAAT for sputum smear–positive and sputum smear–negative TB was 100 and 11.3%, respectively. Sensitivity of ZN smear for AFB of EPTB sample was 48.1% and that of CBNAAT was 59.25%. In both PTB and EPTB, CBNAAT showed an increase in diagnosis of microbiologically confirmed PTB cases by 7.8 and 11.1%, respectively, over and above the cases diagnosed by ZN smear microscopy. Rifampicin resistance was detected in five patients. We conclude that CBNAAT is a rapid test with better sensitivity in diagnosis of PTB and EPTB in PLHIV, compared with ZN smear microscopy. It detects rifampicin resistance for multidrug-resistant TB and helps in early treatment intervention.
What Information Do Clinicians Deem Important for Counseling Parents Facing Extremely Early Deliveries?: Results from an Online Survey
Authors: Kim Brennan Hodgson , Feltman Dalia M. , Schneider Simone , Herron Constance , Montes Andres , Anani Uchenna E. , Murray Peter D. , Arnolds Marin , Krick Jeanne
Published: June 2021

Objective The study aimed to better understand how neonatology and maternal fetal medicine (MFM) physicians convey information during antenatal counseling that requires facilitating shared decision-making with parents facing options of resuscitation versus comfort care after extremely early delivery

Study Design Attending physicians at US centers with both Neo and MFM fellowships were invited to answer an original online survey about antenatal counseling for extremely early newborns. The survey assessed information conveyed, processes for facilitating shared decision-making (reported separately), and clinical experiences. Neonatology and MFM responses were compared. Multivariable logistic regression analyzed topics often and seldom discussed by specialty groups with respect to respondents' clinical experience and resuscitation option preferences at different gestational weeks.

Results In total, 74 MFM and 167 neonatologists representing 94% of the 81 centers surveyed responded. Grouped by specialty, respondents were similar in counseling experience and distribution of allowing choices between resuscitation and no resuscitation for delivery at specific weeks of gestational ages. MFM versus neonatology reported similar rates of discussing long-term health and developmental concerns and differed in all other categories of topics. Neonatologists were less likely than MFM to discuss caregiver impacts (odds ratio [OR]: 0.14, 95% confidence interval [CI]: 0.11–0.18, p < 0.001) and comfort care details (OR: 0.19, 95% CI: 0.15–0.25, p < 0.001). Conversely, neonatology versus MFM respondents more frequently reported “usually” discussing topics pertaining to parenting in the NICU (OR: 1.5, 95% CI: 1.2–1.8, p < 0.001) and those regarding stabilizing interventions in the delivery room (OR: 1.8, 95% CI: 1.4–2.2, p < 0.001). Compared with less-experienced respondents, those with 17 years' or more of clinical experience had greater likelihood in both specialties to say they “usually” discussed otherwise infrequently reported topics pertaining to caregiver impacts.

Conclusion Parents require information to make difficult decisions for their extremely early newborns. Our findings endorse the value of co-consultation by MFM and neonatology clinicians and of trainee education on antenatal consultation education to support these families.

Key Points
High performance WSe2 p-MOSFET with intrinsic n-channel based on back-to-back p–n junctions
Authors: Liu Xiaochi , Pan Yuchuan , Yang Junqiang , Qu Deshun , Li Huamin , Yoo Won Jong , Sun Jian
Published: June 2021

Most of the reported field effect transistors (FETs) in two-dimensional (2D) semiconducting transition metal dichalcogenides (TMDs) are based on the high power consumption Schottky FETs, in which the switching of current relies on the electrostatic modulation of the Schottky barrier at the metal–TMD contact interfaces. Even worse, they have been often mistakenly referred to as 2D metal-oxide-semiconductor field effect transistors (MOSFETs), which, however, have restricted design rules. Here, we demonstrate a two-dimensional p-MOSFET with an intrinsic n-type WSe2 channel. This MOSFET consists of two back-to-back p–n junctions. With a hexagonal boron nitride van der Waals stacking mask, degenerate p-doping to WSe2 from the oxidized surface can be selectively induced to the contact areas by controlled oxygen plasma, while maintaining the center of the channel intrinsic. Compared to Schottky FETs, outstanding device performances are realized, e.g., low field effect threshold, much reduced subthreshold swing, high on/off ratio exceeding 108, hole mobility as high as 191 cm2 V–1 s−1, and hysteresis-free transfer characteristics.
On singularities of dynamic response functions in the massless regime of the XXZ spin-1/2 chain
Authors: Kozlowski Karol K.
Published: June 2021

This work extracts, by means of an exact analysis, the singular behavior of the dynamical response functions—the Fourier transforms of dynamical two-point functions—in the vicinity of the various excitation thresholds in the massless regime of the XXZ spin-1/2 chain. The analysis yields the edge exponents and associated amplitudes that describe the local behavior of the response function near a threshold. The singular behavior is derived starting from first principles considerations: the method of analysis does not rely, at any stage, on some hypothetical correspondence with a field theory or other phenomenological approaches. The analysis builds on the massless form factor expansion for the response functions of the XXZ chain obtained recently by the author. It confirms the non-linear Luttinger based predictions relative to the power-law behavior and of the associated edge exponents that arise in the vicinity of the dispersion relation of one massive excitation (hole, particle, or bound state). In addition, the present analysis shows that due to the lack of strict convexity of the particle dispersion relation and due to the presence of slow velocity branches of the bound states, there exist excitation thresholds with a different structure of edge exponents. These originate from multi-particle/hole/bound state excitations maximizing the energy at fixed momentum.
Ion temperature measurements from tomographic reconstruction of Doppler spectra in the presence of multi-component flow in two dimensions
Authors: Goodman A. , Yoo J. , Jara-Almonte J. , Ji H.
Published: June 2021

A new ion Doppler diagnostic has been constructed to measure ion temperature profiles in the presence of multi-component flow during magnetic reconnection experiments. The inversion technique and diagnostic setup are applicable to axisymmetric plasmas with two-component flow across the measurement cross section, which occurs during magnetic reconnection. The particular design discussed here is optimized for operation on the Magnetic Reconnection eXperiment (MRX) at Princeton Plasma Physics Laboratory. To prove the viability of this diagnostic for MRX and the future Facility for Laboratory Reconnection Experiments, measurements have been taken and ion temperature and perpendicular flow profiles have been obtained. The radial velocity on MRX does not contribute to the Doppler shift of the measured spectra but does contribute to the broadening of the spectra, while toroidal flow contributes to both. It is shown that neglecting the radial velocity for vR = 20 km/s leads to an error in the ion temperature inversion of 20%. Results from MRX discharges are shown, and the impact of radial velocity on ion temperature inversions is discussed.
Design and implementation of a portable diagnostic system for Thomson scattering and optical emission spectroscopy measurements
Authors: Kafle N. , Elliott D. , Garren E. W. , He Z. , Gebhart T. E. , Zhang Z. , Biewer T. M.
Published: June 2021

A diagnostic system, which has a design goal of high-portability, has been designed at Oak Ridge National Laboratory (ORNL). This project aims at providing measurements of key plasma parameters (ne, Te, ni, Ti) for fusion-relevant devices, utilizing Thomson scattering (TS) and optical emission spectroscopy (OES). The innovative design employs mostly commercial off-the-shelf instrumentation and a traveling team of researchers to conduct measurements at various magnetic-confinement plasma devices. The TS diagnostic uses a Quantel Q-smart 1500 Nd:YAG laser with a 2ω harmonic generator to produce up to 850 mJ of 532 nm laser pulses at 10 Hz. Collection optics placed at the detection port consists of an 11 × 3 optical fiber bundle, where the TS diagnostic uses an 11 × 1 subset array of the fibers, the OES diagnostic uses another 11 fibers, and the remaining fibers are available to the host institution. The detection system is comprised of two separate IsoPlane-320 spectrometers with triple-grating turrets of various line spacing and two PI-MAX 4 intensified CCD detectors, used simultaneously to measure a broad range of ion, impurity, and electron parameters. The self-contained diagnostic package also includes a data processing and storage system. The design and initial implementation of the TS-OES diagnostic system are described. The experiments from the proof-of-principle operation of the portable package on a high density (∼2.5 × 1022 m−3) and low-temperature (∼5 eV) electrothermal arc source at ORNL are also discussed.
Ultrasound measurement technique for the single-turn-coil magnets
Authors: Nomura T. , Hauspurg A. , Gorbunov D. I. , Miyata A. , Schulze E. , Zvyagin S. A. , Tsurkan V. , Matsuda Y. H. , Kohama Y. , Zherlitsyn S.
Published: June 2021

Ultrasound is a powerful means to study numerous phenomena of condensed-matter physics as acoustic waves couple strongly to structural, magnetic, orbital, and charge degrees of freedom. In this paper, we present such a technique combined with single-turn coils (STCs) that generate magnetic fields beyond 100 T with the typical pulse duration of 6 µs. As a benchmark of this technique, the ultrasound results for MnCr2S4, Cu6[Si6O18]·6H2O, and liquid oxygen are shown. The resolution for the relative sound-velocity change in the STC is estimated as Δv/v ∼ 10−3, which is sufficient to study various field-induced phase transitions and critical phenomena.
Optimal carrier concentration for FeSb2 colossal thermopower
Authors: Du Qianheng , Petrovic Cedomir
Published: June 2021

Crystals of FeSb2 correlated narrow-gap semiconductor host colossal thermopower values. By tuning the impurity level here, we show that electron–phonon scattering that transfers phonon momentum to electrons is efficient only for certain optimal carrier concentration in the low-mobility band. Phonon drag acting on such states in crystals with high phonon mean free path enhances thermopower to colossal values, whereas for different carrier concentration, dominant thermal transport mechanism is electronic diffusion. This highlights the dual nature of correlated in-gap states that take part in the phonon drag but also reduce phonon mean free path.
Liquid structure transition upon cooling of liquid Pd40Ni40P20
Authors: Yu P. F. , Xia M. , Cao S. C. , Zeng L. , Lu W. Q. , Li J. G.
Published: June 2021

The precipitates of nano-crystals during solidification obscured the initiation of structural evolution, which in turn hid the information for the understanding of nucleation. Here, we report an endothermic liquid–liquid phase transition of Pd40Ni40P20 alloy far before the nucleation and verified with the in situ synchrotron radiation high-energy x-ray diffraction method and flash differential scanning calorimetry (DSC) analysis. The variations on structure factor, pair-distribution functions (PDFs) and coordination number proved a typical structure transition happen at around 640 °C. And the results of flash DSC confirmed the phenomenon. The observation verifies the liquid–liquid phase transition before nucleation and deepens the understanding of solidification in atomic scale.
Sparse optimization of mutual synchronization in collectively oscillating networks
Authors: Nakao Hiroya , Yamaguchi Katsunori , Katayama Shingo , Yanagita Tatsuo
Published: June 2021

We consider a pair of collectively oscillating networks of dynamical elements and optimize their internetwork coupling for efficient mutual synchronization based on the phase reduction theory developed by Nakao et al. [Chaos 28, 045103 (2018)]. The dynamical equations describing a pair of weakly coupled networks are reduced to a pair of coupled phase equations, and the linear stability of the synchronized state between the networks is represented as a function of the internetwork coupling matrix. We seek the optimal coupling by minimizing the Frobenius and L1 norms of the internetwork coupling matrix for the prescribed linear stability of the synchronized state. Depending on the norm, either a dense or sparse internetwork coupling yielding efficient mutual synchronization of the networks is obtained. In particular, a sparse yet resilient internetwork coupling is obtained by L1-norm optimization with additional constraints on the individual connection weights.
A modified C-field circuit for the rubidium atomic clock
Authors: Guo Yonggang , Zhang Jun , Wang Shiwei , Wang Kuan , Wei Lixun , Li Wenxin , Lu Fang , Liu Zhidong , Yang Wei
Published: June 2021

As one of the important circuits of the rubidium atomic clock, the C-field circuit plays a significant role in the rubidium atomic clock’s performance. Generally, a C-field circuit is used to provide a constant current to a C-field coil by forming a weak magnetic field to select two hyperfine mF = 0 energy levels and thus fine-tune the transition frequency of 87Rb. In this way, the C-field circuit has a direct influence on the frequency stability of the rubidium atomic clock. In this paper, by studying the principles and functions of the C-field in a rubidium atomic clock, we propose a modified C-field circuit, which not only provides constant current to the C-field coil but also provides a pathway to improve the performance of the rubidium atomic clock significantly by optimizing the start-up characteristics and temperature coefficient carefully. In addition, according to the theoretical analysis and test verification, the rubidium atomic clock with the proposed C-field circuit improves the temperature coefficient from −1.2 × 10−13 to 2.7 × 10−15/°C, and in addition, the stability of long-term frequency can reach 3.88 × 10−15 at 105 s.
Hydrogen bond effects in multimode nuclear dynamics of acetic acid observed via resonant x-ray scattering
Authors: Savchenko Viktoriia , Ekholm Victor , Brumboiu Iulia Emilia , Norman Patrick , Pietzsch Annette , Föhlisch Alexander , Rubensson Jan-Erik , Gråsjö Johan , Björneholm Olle , Såthe Conny , Dong Minjie , Schmitt Thorsten , McNally Daniel , Lu Xingye , Krasnov Pavel , Polyutov Sergey P. , Gel’mukhanov Faris , Odelius Michael , Kimberg Victor
Published: June 2021

A theoretical and experimental study of the gas phase and liquid acetic acid based on resonant inelastic x-ray scattering (RIXS) spectroscopy is presented. We combine and compare different levels of theory for an isolated molecule for a comprehensive analysis, including electronic and vibrational degrees of freedom. The excitation energy scan over the oxygen K-edge absorption reveals nuclear dynamic effects in the core-excited and final electronic states. The theoretical simulations for the monomer and two different forms of the dimer are compared against high-resolution experimental data for pure liquid acetic acid. We show that the theoretical model based on a dimer describes the hydrogen bond formation in the liquid phase well and that this bond formation sufficiently alters the RIXS spectra, allowing us to trace these effects directly from the experiment. Multimode vibrational dynamics is accounted for in our simulations by using a hybrid time-dependent stationary approach for the quantum nuclear wave packet simulations, showing the important role it plays in RIXS.
A non-intrusive voltage measurement scheme based on MEMS electric field sensors: Theoretical analysis and experimental verification of AC power lines
Authors: Yang Pengfei , Wen Xiaolong , Lv Yao , Chu Zhaozhi , Peng Chunrong
Published: June 2021

A non-interference AC voltage measurement system based on a resonant electric field microsensor is proposed. The equivalent circuit of the proposed system is established, which shows that the frequency response function is only related to the capacitances of the system structure in the kHz low-frequency range. Furthermore, the sensitivity analysis and experiments demonstrate that the amplitude sensitivity is independent of the frequency of an unknown AC voltage. Therefore, this technique is very suitable for measuring arbitrary waveform voltage. A functional prototype was developed and tested to acquire AC power-line voltages. The prototype responded well to the transient waveform of the AC input signal, yet with a phase delay of 177.24°. The output of the system was linear in the range of 0–1000 Vrms at 50-Hz and the linearity was 0.54%, whereas the maximum relative deviation of the rms voltage measurements above 10 V was −0.83%. Finally, the shielding ability of the system against interference and noise was verified through the AC interference voltage measurement.
Revival of oscillation and symmetry breaking in coupled quantum oscillators
Authors: Bandyopadhyay Biswabibek , Banerjee Tanmoy
Published: June 2021

Restoration of oscillations from an oscillation suppressed state in coupled oscillators is an important topic of research and has been studied widely in recent years. However, the same in the quantum regime has not been explored yet. Recent works established that under certain coupling conditions, coupled quantum oscillators are susceptible to suppression of oscillations, such as amplitude death and oscillation death. In this paper, for the first time, we demonstrate that quantum oscillation suppression states can be revoked and rhythmogenesis can be established in coupled quantum oscillators by controlling a feedback parameter in the coupling path. However, in sharp contrast to the classical system, we show that in the deep quantum regime, the feedback parameter fails to revive oscillations, and rather results in a transition from a quantum amplitude death state to the recently discovered quantum oscillation death state. We use the formalism of an open quantum system and a phase space representation of quantum mechanics to establish our results. Therefore, our study establishes that the revival scheme proposed for classical systems does not always result in restoration of oscillations in quantum systems, but in the deep quantum regime, it may give counterintuitive behaviors that are of a pure quantum mechanical origin.
Toward achieving persistent behavior change in household water conservation
Authors: Vivek Vivek , Malghan Deepak , Mukherjee Kanchan
Published: June 2021

Significance

Researchers have been successful in inducing environmental conservation behavior, but the effect is usually transient. Persistence in behavior change has been elusive. We developed a simple, cost-effective, and replicable behavioral intervention for household water conservation that achieved persistence of behavior change. Our method uses objectively defined, sustainability-based per-person goals rather than comparative social norms that can themselves be beyond the threshold of biophysical sustainability or policy goals. Per-person goals help transcend the limitations of extant social comparison interventions that ignore household size. This work also expands the scope of behavioral interventions to settings where resource pricing is not possible or is difficult.
Cadherin puncta are interdigitated dynamic actin protrusions necessary for stable cadherin adhesion
Authors: Li John Xiao He , Tang Vivian W. , Boateng Kingsley A. , Brieher William M.
Published: June 2021

Significance

A major question in tissue biology is how cells manage to maintain stable cell–cell adhesion using the intrinsically weak homophilic bonds of cadherin adhesion molecules. One suggestion is that cells cluster cadherins into large puncta to promote strong adhesion. However, we now show that puncta are not clusters of cadherins but rather interdigitated protruding microspikes. Actin polymerization–dependent protrusive activity generates the interdigitated fingers that help hold the cells together by increasing the membrane surface area available for cadherin–cadherin molecular interactions and by generating a rough, interlocking topography to impede relative movement between cells. The latter, analogous to friction, may offer a physical means of adhesion to compliment the chemical adhesion afforded by cadherin–cadherin homophilic binding.
The balance of giving versus receiving social support and all-cause mortality in a US national sample
Authors: Chen Edith , Lam Phoebe H. , Finegood Eric D. , Turiano Nicholas A. , Mroczek Daniel K. , Miller Gregory E.
Published: June 2021

Significance

Social support is a key contributor to mortality risk, with effects comparable in magnitude (though opposite in direction) to smoking and obesity. Research has largely focused on either support received or support given; yet, everyday social relationships typically involve interchanges of support rather than only giving or only receiving. Using a longitudinal US national sample, this article elucidates how the balance of social support (amount of giving one does on a monthly basis relative to receiving support) relates to all-cause mortality over a 23-y follow-up period. Although correlational, one possible implication of the findings is that encouraging individuals to give support (e.g., helping others with errands) in moderation, while also being willing to accept support, may have longevity benefits.
TMK1-based auxin signaling regulates abscisic acid responses via phosphorylating ABI1/2 in
Arabidopsis
Authors: Yang Jie , He Hang , He Yuming , Zheng Qiaozhen , Li Qingzhong , Feng Xin , Wang Pengcheng , Qin Guocheng , Gu Yangtao , Wu Ping , Peng Chao , Sun Shilei , Zhang Yi , Wen Mingzhang , Chen Rong , Zhao Yang , Xu Tongda
Published: June 2021

Significance

The complex and diverse functions of the phytohormone auxin rely on its concentration. A high concentration of auxin has distinct effects on plant development and environmental adaptation in comparison with a low level of auxin. In this study, we show that a high concentration of auxin is capable of stimulating ABA responses partially through a TMK1-based mechanism. This involves the phosphorylation of ABI1/2, two negative regulators of ABA signaling, and following the activation of downstream ABA responses. Our work reveals the interplay between the phytohormone auxin and ABA, and provides a basis for interpreting differential phytohormone responses during plant development.
A note on coarse graining and group representations
Authors: Bodendorfer Norbert , Haneder Fabian
Published: June 2021

A coarse graining operation of spatially homogeneous quantum states based on an SU(1,1) Lie group structure has recently been proposed in (Bodendorfer and Haneder 2019 Phys. Lett. B 792 69–73) and used in (Bodendorfer and Wuhrer 2020 Class. Quantum Grav.
33 185007) to compute an explicit renormalisation group flow in the context of loop quantum cosmology. In this note, we explain the group theoretical origin of this procedure and generalise previous results based on these insights. We also highlight how the group theoretical origin of these techniques implies their immediate generalisation to other Lie groups.