bluuebunny/crossref_metadata_2025 huggingface dataset:
Static self-induced heterogeneity in glass-forming liquids: Overlap as a microscope
Authors: Guiselin Benjamin , Tarjus Gilles , Berthier Ludovic
Published: April 2022

We propose and numerically implement a local probe of the static self-induced heterogeneity characterizing glass-forming liquids. This method relies on the equilibrium statistics of the overlap between pairs of configurations measured in mesoscopic cavities with unconstrained boundaries. By systematically changing the location of the probed cavity, we directly detect spatial variations of the overlap fluctuations. We provide a detailed analysis of the statistics of a local estimate of the configurational entropy, and we infer an estimate of the surface tension between amorphous states, ingredients that are both at the basis of the random first-order transition theory of glass formation. Our results represent the first direct attempt to visualize and quantify the self-induced heterogeneity underpinning the thermodynamics of glass formation. They pave the way for the development of coarse-grained effective theories and for a direct assessment of the role of thermodynamics in the activated dynamics of deeply supercooled liquids.
DC corral trapping of single nanoparticles and macromolecules in solution
Authors: Carlson Christine A. , Udad Xavier S. , Owen Quintus , Amin-Patel Alaknanda P. , Chang Woo-Jin , Woehl Jörg C.
Published: April 2022

Progress in sorting, separating, and characterizing ever smaller amounts of chemical and biological material depends on the availability of methods for the controlled interaction with nanoscale and molecular-size objects. Here, we report on the reversible, tunable trapping of single DNA molecules and other charged micro- and nanoparticles in aqueous solution using a direct-current (DC) corral trap setup. The trap consists of a circular, non-conductive void in a metal-coated surface that, when charged, generates an electrostatic potential well in the proximate solution. Our results demonstrate that stable, nanoscale confinement of charged objects is achievable over extended periods of time, that trap stiffness is controlled by the applied voltage, and that simultaneous trapping of multiple objects is feasible. The approach shows great promise for lab-on-a-chip systems and biomedical applications due to its simplicity, scalability, selectivity, and the capability to manipulate single DNA molecules in standard buffer solutions.
The influence of a solvent environment on direct non-covalent interactions between two molecules: A symmetry-adapted perturbation theory study of polarization tuning of π–π interactions by water
Authors: Sirianni Dominic A. , Zhu Xiao , Sitkoff Doree F. , Cheney Daniel L. , Sherrill C. David
Published: April 2022

High-level quantum chemical computations have provided significant insight into the fundamental physical nature of non-covalent interactions. These studies have focused primarily on gas-phase computations of small van der Waals dimers; however, these interactions frequently take place in complex chemical environments, such as proteins, solutions, or solids. To better understand how the chemical environment affects non-covalent interactions, we have undertaken a quantum chemical study of π–π interactions in an aqueous solution, as exemplified by T-shaped benzene dimers surrounded by 28 or 50 explicit water molecules. We report interaction energies (IEs) using second-order Møller–Plesset perturbation theory, and we apply the intramolecular and functional-group partitioning extensions of symmetry-adapted perturbation theory (ISAPT and F-SAPT, respectively) to analyze how the solvent molecules tune the π–π interactions of the solute. For complexes containing neutral monomers, even 50 explicit waters (constituting a first and partial second solvation shell) change total SAPT IEs between the two solute molecules by only tenths of a kcal mol−1, while significant changes of up to 3 kcal mol−1 of the electrostatic component are seen for the cationic pyridinium–benzene dimer. This difference between charged and neutral solutes is attributed to large non-additive three-body interactions within solvated ion-containing complexes. Overall, except for charged solutes, our quantum computations indicate that nearby solvent molecules cause very little “tuning” of the direct solute–solute interactions. This indicates that differences in binding energies between the gas phase and solution phase are primarily indirect effects of the competition between solute–solute and solute–solvent interactions.
Extensions to the Navier–Stokes equations
Authors: Wang Shisheng
Published: April 2022

Historically, the mass conservation and the classical Navier–Stokes equations were derived in the co-moving reference frame. It is shown that the mass conservation and Navier–Stokes equations are Galilean invariant—they are valid in any arbitrary inertial reference frame. From the mass conservation and Navier–Stokes equations, we can derive a wave equation, which contains the speed of pressure wave as its parameter. This parameter is independent of the speed of the source—the fluid element velocity. The speed of pressure wave is determined from the thermodynamic equation of state of the fluid, which is reference frame independent. It is well known that Lorentz transformation ensures wave speed invariant in all inertial frames, and the Lorentz invariance holds for different inertial observers. Based on these arguments, general Navier–Stokes equations (conservation law for the energy–momentum) can be written in any arbitrary inertial reference frame, they are transformed from one reference frame into another with the help of the Lorentz transformation. The key issue is that the Lorentz factor is parametrized by the local Mach number. In the instantaneous co-moving reference frame, these equations will degrade to the classical Navier–Stokes equations—the limit of the non-relativistic ones. These extended equations contain a square of the Lorentz factor. When the local Mach number is equal to one (the Lorentz factor approaches infinity), the extended Navier–Stokes equations will embody an intrinsic singularity, meaning that the transitions from the subsonic flow to the supersonic flow will happen. For the subsonic flow, the square of the Lorentz factor is positive, while for the supersonic flow, the square of the Lorentz factor becomes a negative number, which represents that the speed of sound cannot travel upstream faster than the flow velocity.
Boundary condition induced passive chaotic mixing in straight microchannels
Authors: Ouro-Koura Habilou , Ogunmolasuyi Ayobami , Suleiman Othman , Omodia Isaac , Easter Jaylah , Roye Yasmin , Das Kausik S.
Published: April 2022

When fluids flow through straight channels sustained turbulence occurs only at high Reynolds numbers [typically Re∼O(1000)]. It is difficult to mix multiple fluids flowing through a straight channel in the low Reynolds number laminar regime [Re<O(100)] because in the absence of turbulence, mixing between the component fluids occurs primarily via the slow molecular diffusion process. This Letter reports a simple way to significantly enhance the low Reynolds number (in our case Re≤10) passive microfluidic flow mixing in a straight microchannel by introducing asymmetric wetting boundary conditions on the floor of the channel. We show experimentally and numerically that by creating carefully chosen two-dimensional hydrophobic slip patterns on the floor of the channels, we can introduce stretching, folding, and/or recirculation in the flowing fluid volume, the essential elements to achieve mixing in the absence of turbulence. We also show that there are two distinctive pathways to produce homogeneous mixing in microchannels induced by the inhomogeneity of the boundary conditions. It can be achieved either by (1) introducing stretching, folding and twisting of fluid volumes, i.e., via a horse-shoe type transformation map, or (2) by creating chaotic advection, achieved through manipulation of the hydrophobic boundary patterns on the floor of the channels. We have also shown that by superposing stretching and folding with chaotic advection, mixing can be optimized in terms of significantly reducing mixing length, thereby opening up new design opportunities for simple yet efficient passive microfluidic reactors.
Transfer learning using attentions across atomic systems with graph neural networks (TAAG)
Authors: Kolluru Adeesh , Shoghi Nima , Shuaibi Muhammed , Goyal Siddharth , Das Abhishek , Zitnick C. Lawrence , Ulissi Zachary
Published: April 2022

Recent advances in Graph Neural Networks (GNNs) have transformed the space of molecular and catalyst discovery. Despite the fact that the underlying physics across these domains remain the same, most prior work has focused on building domain-specific models either in small molecules or in materials. However, building large datasets across all domains is computationally expensive; therefore, the use of transfer learning (TL) to generalize to different domains is a promising but under-explored approach to this problem. To evaluate this hypothesis, we use a model that is pretrained on the Open Catalyst Dataset (OC20), and we study the model’s behavior when fine-tuned for a set of different datasets and tasks. This includes MD17, the *CO adsorbate dataset, and OC20 across different tasks. Through extensive TL experiments, we demonstrate that the initial layers of GNNs learn a more basic representation that is consistent across domains, whereas the final layers learn more task-specific features. Moreover, these well-known strategies show significant improvement over the non-pretrained models for in-domain tasks with improvements of 53% and 17% for the *CO dataset and across the Open Catalyst Project (OCP) task, respectively. TL approaches result in up to 4× speedup in model training depending on the target data and task. However, these do not perform well for the MD17 dataset, resulting in worse performance than the non-pretrained model for few molecules. Based on these observations, we propose transfer learning using attentions across atomic systems with graph Neural Networks (TAAG), an attention-based approach that adapts to prioritize and transfer important features from the interaction layers of GNNs. The proposed method outperforms the best TL approach for out-of-domain datasets, such as MD17, and gives a mean improvement of 6% over a model trained from scratch.
Moving immersed boundary method for fluid–solid interaction
Authors: Cai Shang-Gui , Ouahsine Abdellatif , Hoarau Yannick
Published: April 2022

A strongly coupled algorithm is presented for the incompressible fluid–rigid body interaction using the moving immersed boundary method. The pressure and the boundary force are treated as Lagrange multipliers to enforce the incompressibility and no-slip wall constraints. To compute the two unknowns from the velocity field, we adopt the fractional step algorithm and successively apply the two constraints. A Poisson equation and a moving force equation are derived for the pressure and the boundary force, respectively. As both coefficient matrices are formulated to be symmetric and positive-definite, the resulting linear systems are solved efficiently with the conjugate gradient solver. The strongly coupled nonlinear fluid–solid system is achieved by a fixed-point iteration. To improve the computational efficiency, we only iterate the moving force equation with the rigid body motion equation, and the time-consuming pressure Poisson equation is solved once the sub-iteration is finished. The proposed method is validated with various benchmark tests, and the results compare well with the literature.
Direct simulation of blood flow with heterogeneous cell suspensions in a patient-specific capillary network
Authors: Ostalowski Kacper , Tan Jifu
Published: April 2022

Three-dimensional (3D) simulations on blood flow in a complex patient-specific retina vascular network were performed considering deformable red blood cells, white blood cells (WBCs), and obstructed vessels. First, the impact of blockage on flow rate distribution (without cells) was investigated. It showed that the blockage might change the flow rate significantly on distant vessels that were not directly connected with the blocked vessel. The flow rate in some vessels could increase up to 1200% due to an obstruction. However, with cells, it showed a fluctuating flow pattern, and the cells showed complicated transport behavior at bifurcations. Cell accumulation might occur in some bifurcations such as a T-shaped junction that eventually led to a physical blockage. The addition of WBCs impacted the local flow rate when they were squeezed through a capillary vessel, and the flow rate could be decreased up to 32% due to the larger size of WBCs. The simulation of flow under stenosis with cells showed that cells could oscillate and become trapped in a vessel due to the fluctuating flow. Finally, a reduced order model (ROM) with multiple non-Newtonian viscosity models was used to simulate the blood flow in the network. Compared with the 3D model, all ROMs reproduced accurate predictions on hematocrit and flow rate distribution in the vascular network. Among them, the Fåhræus–Lindqvist model was found to be the most accurate one. The work can be used to build a multiscale model for blood flow through integration of ROMs and 3D multiphysics models.
Higher-order gap resonance between two identical fixed barges: A study on the effect of water depth
Authors: Ding Yunfeng , Walther Jens Honore , Shao Yanlin
Published: April 2022

Nonlinear piston-mode fluid resonance in the gap formed by two identical fixed barges in close proximity is investigated using a two-dimensional (2D) fully nonlinear numerical wave tank. To delve into the effect of water depth on higher-order resonances in the gap, consistent models are employed to describe the incident waves and wave-structure interactions for finite and shallow water depths. In contrast to previous studies, strong fourth- and fifth-order nonlinear gap resonances are observed under the action of shallow-water waves, resulting in significant higher-harmonic responses that are comparable to the corresponding first and second harmonics. For a given wave height, those waves are found to be more critical than the finite-depth waves, which are capable of evoking second- or third-order gap resonance. Highly oscillatory behavior is observed at the trough under the action of shallow-water waves. This is ascribed to the higher-harmonic diffraction effects, breaking the “perfect cancellation” between the incident-wave harmonics, which should, otherwise, produce smooth and flatter wave trough. Unlike what a linear diffraction theory will predict, the gap response does not behave completely in a quasi-static manner under long cnoidal waves, and the higher harmonics generally show larger phase differences to the corresponding incident-wave components until the resonance occurs. The present study suggests that the water-depth effect and higher harmonics should be consistently accounted for in the design and analysis of side-by-side marine operations in coastal environments involving piston-mode gap responses.
Assessment of XC functionals for the study of organic molecules with superhalogen substitution. A systematic comparison between DFT and CCSD(T)
Authors: Li Jin-Feng , Wang Jia-Hui , Yin Bing
Published: April 2022

A systematic density functional theory study, including 17 exchange–correlation functionals, was performed on 22 composite structures consisting of organic molecules, e.g., ethylene, ethane, and benzene, and superhalogen substitutions arising from [MgX3]− and [Mg2X5]− (X = F, Cl). Range-separated hybrid functionals ωB97M-V, ωB97X-D3(BJ), ωB97XD, ωB97X, and CAM-B3LYP, as well as double-hybrid functionals B2PLYP and DSD-PBEP86-D3(BJ), are verified to provide reliable results with accuracy approaching that at the coupled-cluster single double triple [CCSD(T)] level. The basis set effect of density functional theory calculation is usually moderate, and triple-ξ quality, e.g., Def2-TZVP, is enough in most cases. In addition, the average values from HF and MP2 method, indicated as (MP2 + HF)/2, are also quite close to those of CCSD(T).
Fabrication of (Bi2)m(Bi2Te3)n superlattice films by Te desorption from a pristine Bi2Te3 film
Authors: Kusaka S. , Sasaki T. T. , Sumida K. , Ichinokura S. , Ideta S. , Tanaka K. , Hono K. , Hirahara T.
Published: April 2022

We fabricated superlattice films composed of Bi2 bilayers (BLs) and Bi2Te3 quintuple layers (QLs) by annealing pure Bi2Te3 films. It was found that Te desorbs from the QL to form the BL with an activation energy of 2.7 eV. Eventually, two distinct stoichiometric phases were formed, Bi1Te1 (QL–BL–QL) and Bi4Te3 (QL–BL), as evidenced by scanning transmission emission microscopy measurements. The surface-state dispersion was measured with angle-resolved photoemission spectroscopy, and the topological nature of each sample is discussed. Our method offers a convenient and simple way to fabricate superlattice films with different topological properties.
Rheological model for the alpha relaxation of glass-forming liquids and its comparison to data for DC704 and DC705
Authors: Hecksher Tina , Olsen Niels Boye , Dyre Jeppe C.
Published: April 2022

Dynamic shear-modulus data are presented for two silicone oils DC704 and DC705 for frequencies between 1 mHz and 10 kHz at temperatures covering more than five decades of relaxation-time variation. Data are fitted to the alpha part of a phenomenological model previously shown to describe well the dynamic shear modulus of squalane, which has a large beta process [Hecksher et al., J. Chem. Phys. 146, 154504 (2017)]. That model is characterized by additivity of the alpha and beta shear compliance and by a high-frequency decay of the alpha process in proportion to ω−1/2, where ω is the angular frequency. The fits of the alpha part of this model to the DC704 and DC705 data are compared to fits by a Havriliak–Negami type model, a Barlow–Erginsav–Lamb model, and a Cole–Davidson type model. At all temperatures, the best fit is obtained by the alpha part of the squalane model. This strengthens the conjecture that so-called t-relaxation, leading to high-frequency loss decays proportional to ω−1/2, is generic to the alpha relaxation of supercooled liquids [J. C. Dyre, Phys. Rev. E 74, 021502 (2006); Nielsen et al., J. Chem. Phys. 130, 154508 (2009); and Pabst et al., J. Phys. Chem. Lett. 12, 3685–3690 (2021)].
Physics-informed neural networks for phase-field method in two-phase flow
Authors: Qiu Rundi , Huang Renfang , Xiao Yao , Wang Jingzhu , Zhang Zhen , Yue Jieshun , Zeng Zhong , Wang Yiwei
Published: April 2022

The complex flow modeling based on machine learning is becoming a promising way to describe multiphase fluid systems. This work demonstrates how a physics-informed neural network promotes the combination of traditional governing equations and advanced interface evolution equations without intricate algorithms. We develop physics-informed neural networks for the phase-field method (PF-PINNs) in two-dimensional immiscible incompressible two-phase flow. The Cahn–Hillard equation and Navier–Stokes equations are encoded directly into the residuals of a fully connected neural network. Compared with the traditional interface-capturing method, the phase-field model has a firm physical basis because it is based on the Ginzburg–Landau theory and conserves mass and energy. It also performs well in two-phase flow at the large density ratio. However, the high-order differential nonlinear term of the Cahn–Hilliard equation poses a great challenge for obtaining numerical solutions. Thus, in this work, we adopt neural networks to tackle the challenge by solving high-order derivate terms and capture the interface adaptively. To enhance the accuracy and efficiency of PF-PINNs, we use the time-marching strategy and the forced constraint of the density and viscosity. The PF-PINNs are tested by two cases for presenting the interface-capturing ability of PINNs and evaluating the accuracy of PF-PINNs at the large density ratio (up to 1000). The shape of the interface in both cases coincides well with the reference results, and the dynamic behavior of the second case is precisely captured. We also quantify the variations in the center of mass and increasing velocity over time for validation purposes. The results show that PF-PINNs exploit the automatic differentiation without sacrificing the high accuracy of the phase-field method.
Computer simulation investigation of the adsorption of acetamide on low density amorphous ice. An astrochemical perspective
Authors: Balbisi Mirjam , Horváth Réka A. , Szőri Milán , Jedlovszky Pál
Published: April 2022

The adsorption of acetamide on low density amorphous (LDA) ice is investigated by grand canonical Monte Carlo computer simulations at the temperatures 50, 100, and 200 K, characteristic of certain domains of the interstellar medium (ISM). We found that the relative importance of the acetamide–acetamide H-bonds with respect to the acetamide–water ones increases with decreasing temperature. Thus, with decreasing temperature, the existence of the stable monolayer, characterizing the adsorption at 200 K, is gradually replaced by the occurrence of marked multilayer adsorption, preceding even the saturation of the first layer at 50 K. While isolated acetamide molecules prefer to lay parallel to the ice surface to maximize their H-bonding with the surface water molecules, this orientational preference undergoes a marked change upon saturation of the first layer due to increasing competition of the adsorbed molecules for H-bonds with water and to the possibility of their H-bond formation with each other. As a result, molecules stay preferentially perpendicular to the ice surface in the saturated monolayer. The chemical potential value corresponding to the point of condensation is found to decrease linearly with increasing temperature. We provide, in analogy with the Clausius–Clapeyron equation, a thermodynamic explanation of this behavior and estimate the molar entropy of condensed phase acetamide to be 34.0 J/mol K. For the surface concentration of the saturated monolayer, we obtain the value 9.1 ± 0.8 µmol/m2, while the heat of adsorption at infinitely low surface coverage is estimated to be −67.8 ± 3.0 kJ/mol. Our results indicate that the interstellar formation of peptide chains through acetamide molecules, occurring at the surface of LDA ice, might well be a plausible process in the cold (i.e., below 50 K) domains of the ISM; however, it is a rather unlikely scenario in its higher temperature (i.e., 100–200 K) domains.
Structural and functional insight into mismatch extension by human DNA polymerase α
Authors: Baranovskiy Andrey G. , Babayeva Nigar D. , Lisova Alisa E. , Morstadt Lucia M. , Tahirov Tahir H.
Published: April 2022

Significance

Despite the important role of human DNA polymerase α (Polα) in genome mutagenesis, there are no structural studies of Polα infidelity. The functional studies are sparse, lack high-resolution approaches, and are performed at a low salt concentration. Here we report the structure of the human Polα catalytic domain in the complex with an incoming deoxycytidine triphosphate (dCTP) and the template:primer containing a T-C mismatch at the growing primer terminus. Pre-steady-state and binding kinetics conducted at a physiological salt concentration revealed that Polα has a remarkably lower affinity to DNA and deoxynucleotide triphosphate (dNTP) than reported previously. Strikingly, we found that the incoming dNTP plays a crucial role in Polα interaction with DNA and in discrimination against a mismatched template:primer. This work is important for understanding the mechanism of Polα infidelity and provides a foundation for future studies.
Tumor FAK orchestrates immunosuppression in ovarian cancer via the CD155/TIGIT axis
Authors: Ozmadenci Duygu , Shankara Narayanan Jayanth S. , Andrew Jacob , Ojalill Marjaana , Barrie Allison M. , Jiang Shulin , Iyer Samhita , Chen Xiao Lei , Rose Michael , Estrada Valeria , Molinolo Alfredo , Bertotto Thomas , Mikulski Zbigniew , McHale Michael C. , White Rebekah R. , Connolly Denise C. , Pachter Jonathan A. , Kuchroo Vijay K. , Stupack Dwayne G. , Schlaepfer David D.
Published: April 2022

Significance

High-grade serous ovarian carcinoma (HGSOC) is an immunotherapy-resistant lethal cancer. An HGSOC hallmark is elevated checkpoint pathway ligand expression that limits antitumor immune responses. Computational, preclinical, and patient tumor multiplexed analyses revealed that tumor-associated focal adhesion kinase (FAK) activation regulates CD155 expression, a checkpoint ligand for TIGIT (T cell immunoreceptor with immunoglobulin and immunoreceptor tyrosine-based inhibitory motif domains). Using an aggressive mouse ovarian tumor model, we find that combined oral FAK inhibitor plus function-blocking TIGIT antibody immunotherapy reduced tumor burden, prolonged mouse survival, and led to immune cell activation and tertiary lymphoid structure formation, hallmarks of an antitumor immune response. As FAK is commonly overexpressed in HGSOC tumors, targeting FAK and TIGIT may limit tumor immune evasion.
Listener perceptions of customer service agents’ performance
Authors: Tsunemoto Aki , McAndrews Mark , Trofimovich Pavel , Friginal Eric
Published: April 2022

This study investigated listener-based assessment of the job performance of second language (L2) speakers employed
as customer service agents in outsourced foreign-based call centers, focusing on agents’ job performance as a function of the
comprehensibility, fluency, and accentedness of their speech. Using Amazon’s Mechanical Turk crowdsourcing platform, 116 native
English-speaking listeners evaluated two-minute recordings of actual customer service conversations featuring 18 Filipino agents,
assessing them for three global speech dimensions (comprehensibility, accentedness, and fluency) and three performance indicators,
including agents’ confidence, competence, and listeners’ interest in future communication with agents (a measure capturing
customer patronage). Comprehensibility and fluency consistently predicted how the listeners assessed the agents on all job
performance scales, and accentedness was additionally associated with how strongly the listeners wished to communicate with the
agents. Findings generally highlight the importance of fluent and comprehensible L2 speech in workplace settings.
Collective fear and social representations of COVID-19. The role of the original ‘reasons’ for the fear object (Miedo colectivo y representaciones sociales de la COVID-19. El rol de las ‘razones’ originales para el objeto de miedo)
Authors: Tavani Jean-Louis , Delouvée Sylvain , Rateau Patrick
Published: April 2022

Based on a taxonomy of collective fears, the objective of the study ( N = 1,144) was to analyse how the original reasons attributed to an object of fear play a role in collective angst and to study how these attributions are linked to differentiated social representations of the object. The results show that the underlying reasons (human vs. non-human; intentional vs. unintentional) organize the socio-representational field of the coronavirus. Moreover, the fact of considering the viral epidemic as reversible (vs. irreversible) also plays a role in the socio-representational universe of individuals. Finally, we observe that the attribution of a human origin to the virus is linked to greater collective angst than an attribution to a natural origin. These first results show that it is important to focus on the attribution of the origin of objects of fear in order to understand its consequences in terms of social representations and collective angst.
Investigation of Al-V coatings produced by the thermo-reactive diffusion method
Authors: Troyanovskaya Irina , Veselovsky Alexander , Erofeev Valery , Ignatiev Andrey
Published: April 2022

Creating hardening coatings through thermo-reactive diffusion is an effective method for increasing the service life of cast iron parts. The influence of aluminium on the process of thermo-reactive diffusion of cast irons with vanadium has been studied. It has been found that the concentration of aluminium in the reaction powder medium affects the structure, thickness, and hardness of the coating. The most optimal concentration of aluminium is 0.5–2.5%. This concentration makes it possible to increase the thickness of the hardened coating by 1.5 times with a decrease in microhardness by 10–25% compared to pure vanadization.
Microstructural evolution for a single-crystal superalloy after high-temperature treatments with different holding times
Authors: Wang Yanlin , Zhuo Longchao , Yin Enhuai , Xu Tao , Gong Xiufang
Published: April 2022

In the present work, the thermal heating and cooling behaviour of a single-crystal superalloy containing 2wt-% Re was tested to investigate the γ′ dissolution process, and the surface recrystallisation behaviour of the grit-blasted superalloy was investigated near its ultimate service temperature of 1100°C by EBSD and TEM. Particularly, the aged samples were vertically polished to reveal the progress of the discontinuous precipitation reaction front. The microstructure characteristics, including grain orientation, grain size, texture and TCP phase precipitation, were revealed for a detailed understanding of the surface crystallisation behaviour of the material.
Residual stress prediction in shot blasted cobalt–chromium biomedical cast components
Authors: Shortiss Jack , Tanner David A.
Published: April 2022

ASTM F75 implants distort due to residual stress released after finishing machining operations, causing implants to fail quality requirements. Previous work has shown that a shot blasting cleaning process could be the source of this distortion. Finite element analysis (FEA) is conducted to predict stress and Almen strip arc heights for experimental comparison. 2D and 3D single impact models and 3D multiple impact models are created. 3D multiple impact models with plastically deforming shot are shown to accurately predict the stress state and distortion. For shot with hardness similar to the implants, distortion creating stress magnitudes are induced, with the greatest fluctuations in stress coming from shot velocity. The depth of the predicted compressive stress layer ranges from 0.23 to 0.6 mm.
Pelvic elevation induces vertical kinetic energy without losing horizontal energy during running single‐leg jump for distance
Authors: Sado Natsuki , Yoshioka Shinsuke , Fukashiro Senshi
Published: April 2022

In a running single‐leg jump (RSLJ) for distance, the generation of vertical velocity without loss of horizontal velocity during the take‐off phase is ideal, but difficult; however, we hypothesized that the pelvic rotation in the frontal plane achieved it. Here we show the effect of each segment rotation on the horizontal and vertical kinetic energies ( and ) of the centre of mass (CoM) during the take‐off phase of an RSLJ for distance. We collected kinematic and ground‐reaction‐force data during RSLJs for distance by nine male long jumpers, involving an approximately 20‐m approach in an outdoor field. We determined the components of the and changes due to each segment movement. Elevation of the pelvic free‐leg side increased (0.53±0.16 J/kg, 9±3% of the total change). Pelvic axial rotation decreased , while pelvic elevation did not affect it (0.01±0.02 J/kg, no significant difference from zero). In contrast, forward rotations of the stance‐leg shank and thigh decreased while simultaneously increasing . The results showed that pelvic elevation increased the vertical CoM velocity without causing a loss in horizontal velocity, although the lower‐limb segments’ effects on the vertical and horizontal velocities exhibited a trade‐off, as previously speculated. RSLJs for distance have been frequently assumed as sagittal movements. However, our findings highlight the importance of three‐dimensional pelvic movement, particularly in the frontal plane, for controlling both the vertical and horizontal velocities.
Visualizing intra-Golgi localization and transport by side-averaging Golgi ministacks
Authors: Tie Hieng Chiong , Mahajan Divyanshu , Lu Lei
Published: April 2022

The mammalian Golgi comprises tightly adjacent and flattened membrane sacs called cisternae. We still do not understand the molecular organization of the Golgi and intra-Golgi transport of cargos. One of the most significant challenges to studying the Golgi is resolving Golgi proteins at the cisternal level under light microscopy. We have developed a side-averaging approach to visualize the cisternal organization and intra-Golgi transport in nocodazole-induced Golgi ministacks. Side-view images of ministacks acquired from Airyscan microscopy are transformed and aligned before intensity normalization and averaging. From side-average images of >30 Golgi proteins, we uncovered the organization of the pre-Golgi, cis, medial, trans, and trans-Golgi network membrane with an unprecedented spatial resolution. We observed the progressive transition of a synchronized cargo wave from the cis to the trans-side of the Golgi. Our data support our previous finding, in which constitutive cargos exit at the trans-Golgi while the secretory targeting to the trans-Golgi network is signal dependent.
Ion energy analysis of a bipolar HiPIMS discharge using a retarding field energy analyser
Authors: Walk F , Valizadeh R , Bradley J W
Published: April 2022

The time evolution of the positive ion energy distribution functions (IEDF’s) at the substrate position in an asymmetric bipolar high-power impulse magnetron sputtering (HiPIMS) system was determined using a gridded energy analyser. This was done for a range of operating conditions, namely the positive voltage U
rev and ‘on-time’ negative pulse duration τ
neg. The magnetron sputtering discharge was equipped with a Nb target. Based on the knowledge of the IEDF’s, the bombarding ion flux density Γi and energy flux density Q
i to a grounded surface were calculated. Time-resolved IEDF measurements showed that ions with energies approaching the equivalent of the positive pulse voltage U
rev were generated as the reverse positive voltage phase developed. On time-average, we observed that increasing the set U
rev value (from 0 to 100 V), resulted in a marginal decrease in the ion flux density Γi to the analyser. However, this is accompanied by a five-fold increase in the ion energy flux density Q
i compared to the unipolar, U
rev = 0 V case. Reducing the negative HiPIMS pulse duration τ
neg (from 130 to 40 μs) at a constant discharge power leads to a modest increase in Γi, but a four-fold increase in Q
i. The results reveal the benefit of the bipolar HiPIMS technique, in which it is possible to control and enhance the power density of ions bombarding a grounded (or fixed bias) substrate, for potentially better tailoring of thin film properties.
Modeling and experimental investigation of asymmetric distance with magnetic coupling based on galloping piezoelectric energy harvester
Authors: Zhang Huirong , Zhang Leian , Wang Yuanbo , Yang Xiaohui , Song Rujun , Sui Wentao
Published: April 2022

This paper presents an asymmetric magnetic coupling piezoelectric energy harvester (PEH) based on galloping to scavenge low-speed wind. The piezoelectric beam of energy harvester undergoes bending and torsional vibration simultaneously due to the eccentric distance. By analyzing the kinetic energy, potential energy, and virtual work of the energy harvesting system, the mathematical model of harvester is constructed and verified by experiments. The optimal external load resistance is confirmed at different eccentric distances and wind speeds by experiments. Compared with traditional galloping piezoelectric energy harvester (GPEH), the asymmetric with magnetically coupling GPEH has a lower threshold wind speed, i.e. 2 m s−1. And the asymmetric configuration contributes to a lower natural frequency and electromechanical coupling coefficient, which results in a lower power and voltage output. The potential energy of harvesting systems at different distances between two magnets are respectively numerical analyzed in detail. The theoretical results illustrate that the energy harvester operates in monostable and bistable at different magnet distances. And the threshold wind speed of energy harvester increases when the energy harvester works at bistable. According to the above analysis, this work provides a detailed guideline for mathematical modeling and performance improvement of asymmetric PEH based on galloping.
Low-loss superconducting aluminum microwave coplanar waveguide resonators on sapphires for the qubit readouts
Authors: He Q , OuYang P , Gao H , He S , Li Y , Wang Y , Chen Y , Dai X , Wang Y , Wei L F
Published: April 2022

The coplanar waveguide (CPW) microwave resonators have been widely applied for solid-state quantum computation and single-photon detection. Based on the physical analysis for the high fidelity readouts of the qubit(s), in this paper we design and then fabricate accordingly the desired aluminum (Al) film quarter-wavelength resonators on sapphire substrates. The ultra-low temperature measurement results show that the linearity of the internal quality factor under the proper driving power is satisfied well for the high fidelity readouts of the qubit(s); and the phase- and amplitude fractional frequency noises are significantly less for avoiding the potential information false alarms of the detected qubit during the readouts. With the demonstrated qubit-resonator experimental parameters, we argue that the designed and fabricated quarter-wavelength CPW resonators, with optimized parameters, can be used to implement the desired weakly perturbing readout measurements of the solid-state qubits on-chip.
Work costs and operating regimes for different manners of system-reservoir interactions via collision model
Authors: Wang Ying , Man Zhong-Xiao , Zhang Ying-Jie , Xia Yun-Jie
Published: April 2022

In this work, we study effects of different types of system-reservoir interactions on work costs and operating regimes of thermal machines by considering a quantum system consisting of two subsystems embedded in both independent and common reservoirs. The model allows us to make a contrast between three configurations of system-reservoir interactions, namely, the three-body one, the two-body one with and without intrasystem interaction between two subsystems. After establishing general formulations of thermodynamics quantities, we derive specific forms of heat and work with respect to these three configurations based on a model with two coupled qubits. It is shown that both the amount and sign of work are closely related to ways of system-reservoir interactions, by which six types of operating regimes of machines are constructed for a given setting. We find that different modes of system-reservoir interactions lead to different numbers of operating regimes of machines on the one hand, and on the other hand machines of the same kinds can appear in different scenarios of system-reservoir interactions, but which one is superior over others relies on intervals of parameters. A possible implementation of the setup based on the platform of circuit quantum electrodynamics is discussed briefly. We then generalize the bipartite model to multipartite case and derive the corresponding formulations of thermodynamics quantities. Our results indicate that interacting manners of system-reservoir play an important role in modifying thermodynamics process and can thus be utilized in designing quantum thermal machines with requisite functions.
New exact solutions to the Eddington-inspired-Born-Infeld equations for a relativistic perfect fluid in a Bianchi type I spacetime
Authors: Tadmon Calvin , Djiodjo-Seugmo Guichard
Published: April 2022

We consider a Bianchi type I physical metric g, an auxiliary metric q and a density matter ρ in Eddington-inspired-Born-Infeld theory. We first derive a system of second order nonlinear ordinary differential equations. Then, by a suitable change of variables, we arrive at a system of first order nonlinear ordinary differential equations. Using both the solution-tube concept for the first order nonlinear ordinary differential equations and the nonlinear analysis tools such as the Arzelá–Ascoli theorem, we prove an existence result for the nonlinear system obtained. The resolution of this last system allows us to obtain new exact solutions for the model considered. Finally, by studying the asymptotic behaviour of the exact solutions obtained, we conclude that this solution is the counterpart of the Friedman–Lemaître–Robertson–Walker spacetime in Eddington-inspired-Born-Infeld theory.
Protected two-qubit entangling gate with mechanical driven continuous dynamical decoupling
Authors: Sun Xue-Jian , Liu Wen-Xiao , Chen Hao , Wang Cheng-Yuan , Ma Hui-Zhong , Li Hong-Rong
Published: April 2022

In this work, we propose a high-fidelity phonon-mediated entangling gate in a hybrid mechanical system based on two silicon-vacancy color centers in diamond. In order to suppress the influence of the spin decoherence on the entangling gate, we use a continuous dynamical decoupling approach to create new dressed spin states, which are less sensitive to environmental fluctuations and exhibit an extended

T

2

*

spin dephasing time. The effective spin–spin Hamiltonian modified by the mechanical driving field and the corresponding master equation are derived in the dispersive regime. We show that in the presence of the mechanical driving field, the effective spin–spin coupling can be highly controlled. By calculating the entangling gate fidelity in the dressed basis, we find that once the mechanical field is turned on, the gate fidelity can be significantly improved. In particular, under an optimized spin-phonon detuning and a stronger Rabi frequency of the mechanical driving field, the two-qubit gate is capable of reaching fidelity exceeding 0.99. Moreover, by employing appropriate driving modulation, we show that a high-fidelity full quantum gate can be also realized, in which the initial and final spin states are on a bare basis. Our work provides a promising scheme for realizing high-fidelity quantum information processing.
Experimental and simulation studies of localization and decoding of single and double dipoles
Authors: Zhang Hao , Xu Minpeng , Zhang Chen , He Feng , Song Xizi , Chen Shanguang , Jian Xiqi , Ming Dong
Published: April 2022

Objective. Electroencephalography is a technique for measuring normal or abnormal neuronal activity in the human brain, but its low spatial resolution makes it difficult to locate the precise locations of neurons due to the volume conduction effect of brain tissue. Approach. The acoustoelectric (AE) effect has the advantage of detecting electrical signals with high temporal resolution and focused ultrasound with high spatial resolution. In this paper, we use dipoles to simulate real single and double neurons, and further investigate the localization and decoding of single and double dipoles based on AE effects from numerical simulations, brain tissue phantom experiments, and fresh porcine brain tissue experiments. Main results. The results show that the localization error of a single dipole is less than 0.3 mm, the decoding signal is highly correlated with the source signal, and the decoding accuracy is greater than 0.94; the location of double dipoles with an interval of 0.4 mm or more can be localized, the localization error tends to increase as the interval of dipoles decreases, and the decoding accuracy tends to decrease as the frequency of dipoles decreases. Significance. This study localizes and decodes dipole signals with high accuracy, and provides a technical method for the development of EEG.
Rectification in a mixture of active and passive particles subject to a ratchet potential
Authors: Derivaux Jean-François , Jack Robert L , Cates Michael E
Published: April 2022

We study by simulation a mixture of active (run-and-tumble) and passive (Brownian) particles with repulsive exclusion interactions in one dimension, subject to a ratchet (smoothed sawtooth) potential. Such a potential is known to rectify active particles at one-body level, creating a net current in the ‘easy direction’. This is the direction in which one encounters the lower maximum force en route to the top of a potential barrier. The exclusion constraint results in single-file motion, so the mean velocities of active and passive particles are identical; we study the effects of activity level, Brownian diffusivity, particle size, initial sequence of active and passive particles, and active/passive concentration ratio on this mean velocity (i.e. the current per particle). We show that in some parameter regimes the sign of the current is reversed. This happens when the passive particles are at high temperature and so would cross barriers relatively easily, and without rectification, except that they collide with ‘cold’ active ones, which would otherwise be localized near the potential minima. In this case, the reversed current arises because hot passive particles push cold active ones preferentially in the direction with the lower spatial separation between the bottom and top of the barrier. A qualitatively similar mechanism operates in a mixture containing passive particles of two very different temperatures, although there is no quantitative mapping between that case and the systems studied here.
Modelling and investigation of the stress state in a finite cylinder with a circular crack under sudden torsional loading
Authors: Demydov O V , Popov V G
Published: April 2022

This paper is devoted to the analysis of the dynamic stress state of a finite cylinder with an internal circular crack. One of the cylinder’s bases is fixed, and a time-dependent torque is applied to the other base. For solving this problem, a modified finite difference method was applied. This method consists in the difference approximation of only the time derivative. As a result, the original problem is reduced to a set of sequentially solved homogeneous boundary value problems. Their solutions contain an unknown displacement jump on the crack. The integral equation for the unknown jump is reduced to the Fredholm integral equation of the second kind, which was solved numerically. This numerical solution made it possible to obtain an approximate formula for calculating the stress intensity factor (SIF).
Methods for determining shear resistance by a system of cracks and old slip surfaces with the purpose to evaluate the stability of landslides
Authors: Hayroyan S G , Hayroyan H S
Published: April 2022

On slopes, landslide displacements mainly occur along bedding boundaries, lithogenetic and tectonic fractures, as well as along existing ancient slip surfaces, which are the weak zones and potential slip surfaces for new landslides.

According to experimental studies to determine the shear resistance by the standard and double cut test methods: a) without wetting the sliding surface, and b) by the wetting the sliding surface, we can conclude: when double- cutting the clay soils of a solid, semi-solid and tight-plastic consistency, the cohesion is mainly reduced, but the internal friction factor is slightly changed.

Double-cut tests of soft-plastic and flow-plastic clay soils have shown the cohesion and the internal friction factors are being changed insignificantly.

At the same time, taking into account the fact that under the condition τ > σ tan φ the soft-plastic and flowing-plastic clay soils undergo viscous-plastic deformations, we come to the following conclusion.

When developing the anti-landslide measures, independent of the consistency of the soils forming the slope, the τf
= σ tan φ component should be taken as the slip resistance index in the formula for calculating the slip resistance taking into account the condition Cc
+ Σ
w
= 0.