bluuebunny/crossref_metadata_2025 huggingface dataset:
An immersed boundary-lattice Boltzmann flux solver for simulation of flows around structures with large deformation
Authors: Zhang Hua , Liu Yaguang , Zhang Zehua , Wang Lian-Ping , Shu Chang
Published: March 2023

In this paper, we present an immersed boundary-lattice Boltzmann flux solver (IB-LBFS) to simulate the interactions of viscous flow with deformable elastic structures, namely, two-dimensional (2D) and three-dimensional (3D) capsules formed by elastic membranes. The IB-LBFS is based on a finite-volume formulation and makes use of hydrodynamic conservation equations with fluxes computed by a kinetic approach; thus, it is more flexible and efficient than the standard immersed boundary-lattice Boltzmann methods. The membrane of the 2D capsule is represented by a set of discrete Lagrangian points, with in-plane and bending forces acting on the membrane obtained by a finite difference method. In contrast, the membrane of a 3D capsule is discretized into flat triangular elements with membrane forces calculated by an energy-based finite-element method. The IB-LBFS is first validated by studying the deformation of a circular capsule in a linear Newtonian and a power-law shear flow. Next, the deformation dynamics of a spherical, an oblate spheroidal, and a biconcave capsule in a simple shear flow are simulated. For an initially spherical capsule, the tank-treading motion of its membrane is reproduced at the steady state; while for oblate spheroidal and biconcave capsules, the swinging and tumbling motions are observed. Furthermore, under certain parameter settings, the transient mode from tumbling to swinging motions is also found, showing a rich and complex dynamic behavior of non-spherical capsules. These results indicate that the IB-LBFS can be employed in future studies concerning the dynamics of a capsule suspension in more realistic flows.
Temperature resolved decay time components of Mg4FGeO6:Mn using the maximum entropy method
Authors: Feuk Henrik , Nilsson Sebastian , Richter Mattias
Published: March 2023

A thermographic phosphor’s decay time distribution over its temperature-sensitive range was retrieved with the Maximum Entropy Method (MEM). A decay time distribution consists of a range of decay times, each with an associated weighting for the decay time component’s prevalence in the analyzed decay curve. With the MEM, significant decay time contributions of a decay curve have high weighting and are therefore found as peaks in the decay time distribution, where the width and peak value are correlated with the relative weight of the decay time components. These peaks in the decay time distribution give increased insight into a phosphor’s lifetime behavior, which often cannot accurately be represented by a single or even two decay time components. The changes in the location of peaks in the decay time distribution with temperature can be used for thermometry, and this method has the benefit of being less sensitive to the multi-exponentiality of phosphor decay than mono-exponential decay time fitting. The method also resolves the underlying decay components with no assumptions of the number of significant decay time components. Initially, when the decay time distribution of Mg4FGeO6:Mn was captured, the collected decay included decaying luminescence from the alumina oxide tube in the tube furnace. Therefore, a second calibration was performed where the luminescence from the alumina oxide tube was minimized. These two calibration datasets were used to demonstrate that the MEM could characterize decays from two separate sources simultaneously.
Non-equilibrium extension of the explicit algebraic subgrid-scale stress model with application to turbulent channel flow at low Reynolds numbers
Authors: Pouransari Zeinab , Rasam Amin
Published: March 2023

An extension of the explicit algebraic subgrid-scale (SGS) stress model (EASSM) of Marstorp et al. [J. Fluid Mech. 639, 403–432 (2009)] is proposed to account for the non-local equilibrium between the production, P, and viscous dissipation, ϵ, of the SGS turbulent kinetic energy in its formulation. The original derivation of the EASSM uses the equilibrium assumption P=ϵ, whereas in the current new derivation, a cubic algebraic equation is extracted for P/ϵ from the modeled transport equation for the SGS stress anisotropy, which can be solved to improve the EASSM predictions with less than 4% additional computational costs per time step. The performance of the extended EASSM is assessed in large-eddy simulation of plane turbulent channel flow at Reτ=587 and 179 for a wide range of resolutions, where deviations from the local equilibrium assumption are expected at the vicinity of the walls. The enhanced EASSM formulation lowers resolution dependence of the model predictions and improves its predictions at low resolutions. The improvements affected major one-point turbulence statistics of interest, such as the wall shear stress, mean velocity, Reynolds stresses, and SGS dissipation as well as the two-point velocity correlations and premultiplied spanwise spectra of the streamwise velocity. The predicted mean P/ϵ also reasonably agrees with the filtered direct numerical simulation data.
Inertial effects on rectification and diffusion of active Brownian particles in an asymmetric channel
Authors: Khatri Narender , Kapral Raymond
Published: March 2023

Micro- and nano-swimmers, moving in a fluid solvent confined by structures that produce entropic barriers, are often described by overdamped active Brownian particle dynamics, where viscous effects are large and inertia plays no role. However, inertial effects should be considered for confined swimmers moving in media where viscous effects are no longer dominant. Here, we study how inertia affects the rectification and diffusion of self-propelled particles in a two-dimensional, asymmetric channel. We show that most of the particles accumulate at the channel walls as the masses of the particles increase. Furthermore, the average particle velocity has a maximum as a function of the mass, indicating that particles with an optimal mass Mop* can be sorted from a mixture with particles of other masses. In particular, we find that the effective diffusion coefficient exhibits an enhanced diffusion peak as a function of the mass, which is a signature of the accumulation of most of the particles at the channel walls. The dependence of Mop* on the rotational diffusion rate, self-propulsion force, aspect ratio of the channel, and active torque is also determined. The results of this study could stimulate the development of strategies for controlling the diffusion of self-propelled particles in entropic ratchet systems.
Circulation production model and unified formation number of compressible vortex rings generated by a shock tube
Authors: Xiang Yang , Qin Liang , Qin Suyang , Liu Hong
Published: March 2023

To investigate the formation number of compressible vortex rings (CVRs), a shock-tube apparatus with an open end is designed to generate CVRs and the flow structures are measured by using particle image velocity (PIV) and time-resolved schlieren techniques. A series of experiments were designed by varying the two governing factors: Mach numbers of the incident shock (Ms= 1.28, 1.48, and 1.59) and driven section length (DL = 100, 200, and 300 mm). By theoretically analyzing the shock diffraction problem, a slipstream model is proposed to predict the circulation generation of CVRs. Comparing with the PIV results, this model well predicts the circulation for Ms=1.28 but slightly underestimates the circulation for Ms= 1.48 and 1.59. Then, an alternative model based on the variation of Ms is proposed and well predicts the circulation generation. Based on the general definition of the vortex formation time and the circulation production model, we newly define the physical formation time of CVRs and then determine the formation number (denoted by F*) when CVRs pinch off. The formation number of CVRs (F*≈3.5) is found to coincide with the optimal vortex formation number originated from incompressible vortex rings (ICVRs). This consistency generalizes the principle of optimal vortex formation into compressible flows. However, both the PIV and schlieren results demonstrate that the CVRs for different Ms pinch off in different modes. With the aim of modulating F* of CVRs, a converging nozzle is designed, and we found that F*≈3.5 is remained for Ms = 1.28 but F* = 5.5 and 6.0 is obtained for Ms= 1.48 and 1.59. Furthermore, an extension of the Kelvin–Benjamin variational principle is explored to explain the unified formation number of CVRs and ICVRs.
Estimation of bubble cavitation rates in a symmetrical Lennard-Jones mixture by NVT seeding simulations
Authors: Lamas Cintia P. , Sanz Eduardo , Vega Carlos , Noya Eva G.
Published: March 2023

The liquid–vapor transition starts with the formation of a sufficiently large bubble in the metastable liquid to trigger the phase transition. Understanding this process is of fundamental and practical interest, but its study is challenging because it occurs over timescales that are too short for experiments but too long for simulations. The seeding method estimates cavitation rates by simulating a liquid in which a bubble is inserted, thus avoiding the long times needed for its formation. In one-component systems, in the NpT ensemble, the bubble grows or redissolves depending on whether its size is larger or smaller than the critical size, whereas in the NVT ensemble (i.e., at constant number of particles, volume, and temperature), the critical bubble can remain in equilibrium. Provided that a good criterion is used to determine the bubble size, this method, combined with the Classical Nucleation Theory (CNT), gives cavitation rates consistent with those obtained by methods independent of the CNT. In this work, the applicability of NVT seeding to homogeneous cavitation in mixtures is demonstrated, focusing on a partially miscible symmetrical binary Lennard-Jones (LJ) liquid at a temperature within the mixing regime. At the same stretching pressure, cavitation rates are higher in the binary mixture than in the pure liquid due to the lower interfacial free energy of the mixture. Curiously, the cost of creating a bubble is similar in the pure and binary LJ liquids at the same metastability, Δμ/Δμspin, with Δμ being the difference in chemical potential between the metastable liquid and coexistence, and Δμspin between the spinodal and coexistence.
Thermocapillary migration of a deformed droplet in the combined vertical temperature gradient and thermal radiation
Authors: Wu Zuo-Bing
Published: March 2023

Thermocapillary migration of a deformed droplet in the combined vertical temperature gradient and thermal radiations with uniform and non-uniform fluxes is first analyzed. The creeping flow solutions show that the deformed droplet has a slender or a cardioid shape, which depends on the form of the radiation flux. The deviation from a sphere depends not only on the viscosity and the conductivity ratios of two-phase fluids but also on capillary and thermal radiation numbers. Moreover, in the roles of interfacial rheology on thermocapillary migration of a deformed droplet, only the surface dilatational viscosity and the surface internal energy can reduce the steady migration velocity, but the surface shear viscosity has not any effects on the steady migration velocity. The surface shear and dilatational viscosities affect the deformation of the droplet by increasing the viscosity ratio of two-phase fluids. The surface internal energy directly reduces the deformation of the droplet. However, the deformed droplet still keeps its original shape without the influence of interfacial rheology. Furthermore, it is found that, based on the net force balance condition of the droplet, the normal stress balance at the interface can be used to determine the steady migration velocity, which is not affected by the surface deformation in the creeping flow. From the expressions of the normal/the tangential stress balance, it can be proved that the surface shear viscosity does not affect the steady migration velocity. The results could not only provide a valuable understanding of thermocapillary migration of a deformed droplet with/without the interfacial rheology in a vertical temperature gradient controlled by thermal radiation but also inspire its potential practical applications in microgravity and microfluidic fields.
Full continuum approach for simulating plume-surface interaction in planetary landings
Authors: Ejtehadi Omid
Published: March 2023

A high-fidelity computational framework for predicting the interaction of a rocket plume with a dust blanket in an almost vacuum ambient that represents the descent/ascend phase of planetary landing is developed. Compared to the existing continuum frameworks, the developed tool benefits from nonlinear-coupled constitutive relationships obtained using a method of moments approach to tackle the non-equilibrium effects in the rarefied condition. The two-phase flow is modeled in an Eulerian framework that allows for the simulation of a wider range of solid regimes compared to the Lagrangian counterpart. Simulations were conducted to analyze the cratering phenomena and regolith ejecta dynamics. Moreover, the vorticity growth rates were analyzed using a new vorticity transport equation (VTE) by including the bulk viscosity and multiphase terms to demonstrate the contribution of each term to the formation of counterintuitive festooned patterns on the surface owing to jet impingement. This analysis identified a new contributing mechanism responsible for the scour patterns. Although all the investigated terms in the VTE contribute to such patterns, the viscous term has more effect during the entire investigation period. Furthermore, studies on particulate loading, particle diameter, and bed height were conducted to highlight the role of these parameters on brownout phenomena and scour formation patterns. The simulation results depict that the generated vortex core beneath the nozzle is highly dependent on the diameter of the particles as well as the bed height: an increase in the height of the bed and particle diameter can lead to a more favorable brownout status.
Species invasions shift microbial phenology in a two-decade freshwater time series
Authors: Rohwer Robin R. , Hale Riley J. , Vander Zanden M. Jake , Miller Todd R. , McMahon Katherine D.
Published: March 2023

Invasive species impart abrupt changes on ecosystems, but their impacts on microbial communities are often overlooked. We paired a 20 y freshwater microbial community time series with zooplankton and phytoplankton counts, rich environmental data, and a 6 y cyanotoxin time series. We observed strong microbial phenological patterns that were disrupted by the invasions of spiny water flea (
Bythotrephes cederströmii
) and zebra mussels (
Dreissena polymorpha
). First, we detected shifts in
Cyanobacteria
phenology. After the spiny water flea invasion,
Cyanobacteria
dominance crept earlier into clearwater; and after the zebra mussel invasion,
Cyanobacteria
abundance crept even earlier into the diatom-dominated spring. During summer, the spiny water flea invasion sparked a cascade of shifting diversity where zooplankton diversity decreased and
Cyanobacteria
diversity increased. Second, we detected shifts in cyanotoxin phenology. After the zebra mussel invasion, microcystin increased in early summer and the duration of toxin production increased by over a month. Third, we observed shifts in heterotrophic bacteria phenology. The
Bacteroidota
phylum and members of the acI
Nanopelagicales
lineage were differentially more abundant. The proportion of the bacterial community that changed differed by season; spring and clearwater communities changed most following the spiny water flea invasion that lessened clearwater intensity, while summer communities changed least following the zebra mussel invasion despite the shifts in
Cyanobacteria
diversity and toxicity. A modeling framework identified the invasions as primary drivers of the observed phenological changes. These long-term invasion-mediated shifts in microbial phenology demonstrate the interconnectedness of microbes with the broader food web and their susceptibility to long-term environmental change.
Self-propelling colloids with finite state dynamics
Authors: van Kesteren Steven , Alvarez Laura , Arrese-Igor Silvia , Alegria Angel , Isa Lucio
Published: March 2023

Endowing materials with the ability to sense, adapt, and respond to stimuli holds the key to a progress leap in autonomous systems. In spite of the growing success of macroscopic soft robotic devices, transferring these concepts to the microscale presents several challenges connected to the lack of suitable fabrication and design techniques and of internal response schemes that connect the materials’ properties to the function of the active units. Here, we realize self-propelling colloidal clusters which possess a finite number of internal states, which define their motility and which are connected by reversible transitions. We produce these units via capillary assembly combining hard polystyrene colloids with two different types of thermoresponsive microgels. The clusters, actuated by spatially uniform AC electric fields, adapt their shape and dielectric properties, and consequently their propulsion, via reversible temperature-induced transitions controlled by light. The different transition temperatures for the two microgels enable three distinct dynamical states corresponding to three illumination intensity levels. The sequential reconfiguration of the microgels affects the velocity and shape of the active trajectories according to a pathway defined by tailoring the clusters’ geometry during assembly. The demonstration of these simple systems indicates an exciting route toward building more complex units with broader reconfiguration schemes and multiple responses as a step forward in the pursuit of adaptive autonomous systems at the colloidal scale.
Darwinian evolution as a dynamical principle
Authors: Kocher Charles D. , Dill Ken A.
Published: March 2023

Darwinian evolution (DE)—biology’s powerful process of adaptation—is remarkably different from other known dynamical processes. It is antithermodynamic, driving away from equilibrium; it has persisted for 3.5 billion years; and its target, fitness, can seem like “Just So” stories. For insights, we make a computational model. In the Darwinian Evolution Machine (DEM) model, resource-driven duplication and competition operate inside a cycle of search/compete/choose. We find the following: 1) DE requires multiorganism coexistence for its long-term persistence and ability to cross fitness valleys. 2) DE is driven by resource dynamics, like booms and busts, not just by mutational change. And, 3) fitness ratcheting requires a mechanistic separation between variation and selection steps, perhaps explaining biology’s use of separate polymers, DNA and proteins.
Computational design of BclxL inhibitors that target transmembrane domain interactions
Authors: Duart Gerard , Elazar Assaf , Weinstein Jonathan Y. , Gadea-Salom Laura , Ortiz-Mateu Juan , Fleishman Sarel J. , Mingarro Ismael , Martinez-Gil Luis
Published: March 2023

Several methods have been developed to explore interactions among water-soluble proteins or regions of proteins. However, techniques to target transmembrane domains (TMDs) have not been examined thoroughly despite their importance. Here, we developed a computational approach to design sequences that specifically modulate protein–protein interactions in the membrane. To illustrate this method, we demonstrated that BclxL can interact with other members of the B cell lymphoma 2 (Bcl2) family through the TMD and that these interactions are required for BclxL control of cell death. Next, we designed sequences that specifically recognize and sequester the TMD of BclxL. Hence, we were able to prevent BclxL intramembrane interactions and cancel its antiapoptotic effect. These results advance our understanding of protein–protein interactions in membranes and provide a means to modulate them. Moreover, the success of our approach may trigger the development of a generation of inhibitors targeting interactions between TMDs.
Standing genetic variation and chromosome differences drove rapid ecotype formation in a major malaria mosquito
Authors: Small Scott T. , Costantini Carlo , Sagnon N’Fale , Guelbeogo Moussa W. , Emrich Scott J. , Kern Andrew D. , Fontaine Michael C. , Besansky Nora J.
Published: March 2023

Species distributed across heterogeneous environments often evolve locally adapted ecotypes, but understanding of the genetic mechanisms involved in their formation and maintenance in the face of gene flow is incomplete. In Burkina Faso, the major African malaria mosquito
Anopheles funestus
comprises two strictly sympatric and morphologically indistinguishable yet karyotypically differentiated forms reported to differ in ecology and behavior. However, knowledge of the genetic basis and environmental determinants of
An. funestus
diversification was impeded by lack of modern genomic resources. Here, we applied deep whole-genome sequencing and analysis to test the hypothesis that these two forms are ecotypes differentially adapted to breeding in natural swamps versus irrigated rice fields. We demonstrate genome-wide differentiation despite extensive microsympatry, synchronicity, and ongoing hybridization. Demographic inference supports a split only ~1,300 y ago, closely following the massive expansion of domesticated African rice cultivation ~1,850 y ago. Regions of highest divergence, concentrated in chromosomal inversions, were under selection during lineage splitting, consistent with local adaptation. The origin of nearly all variations implicated in adaptation, including chromosomal inversions, substantially predates the ecotype split, suggesting that rapid adaptation was fueled mainly by standing genetic variation. Sharp inversion frequency differences likely facilitated adaptive divergence between ecotypes by suppressing recombination between opposing chromosomal orientations of the two ecotypes, while permitting free recombination within the structurally monomorphic rice ecotype. Our results align with growing evidence from diverse taxa that rapid ecological diversification can arise from evolutionarily old structural genetic variants that modify genetic recombination.
Whose input matters?
Authors: Hayes-Harb Rachel , Barrios Shannon L. , Tripp Alayo
Published: March 2023

Input is a necessary condition for language acquisition. In the language classroom, input may come from a variety of sources, including the teacher and student peers. Here we ask whether adult Lx learners are sensitive to the social roles of teachers and students such that they exhibit a preference for input from the teacher. We conducted an experiment wherein adult English speakers heard words in an artificial language. During an exposure phase, in one condition a “teacher” produced words with 25 ms of VOT on initial stop segments and a “student” produced the same words with 125 msec of VOT; in another condition the VOT durations were reversed. At test, participants judged productions by a different “student” and demonstrated a preference for the productions that matched the VOT durations of the teacher during exposure, providing evidence for an influence of social factors in differentiating input in Lx acquisition.
N-terminal truncated cardiac troponin I enhances Frank-Starling response by increasing myofilament sensitivity to resting tension
Authors: Feng Han-Zhong , Huang Xupei , Jin Jian-Ping
Published: March 2023

Cardiac troponin I (cTnI) of higher vertebrates has evolved with an N-terminal extension, of which deletion via restrictive proteolysis occurs as a compensatory adaptation in chronic heart failure to increase ventricular relaxation and stroke volume. Here, we demonstrate in a transgenic mouse model expressing solely N-terminal truncated cTnI (cTnI-ND) in the heart with deletion of the endogenous cTnI gene. Functional studies using ex vivo working hearts showed an extended Frank-Starling response to preload with reduced left ventricular end diastolic pressure. The enhanced Frank-Starling response effectively increases systolic ventricular pressure development and stroke volume. A novel finding is that cTnI-ND increases left ventricular relaxation velocity and stroke volume without increasing the end diastolic volume. Consistently, the optimal resting sarcomere length (SL) for maximum force development in cTnI-ND cardiac muscle was not different from wild-type (WT) control. Despite the removal of the protein kinase A (PKA) phosphorylation sites in cTnI, β-adrenergic stimulation remains effective on augmenting the enhanced Frank-Starling response of cTnI-ND hearts. Force–pCa relationship studies using skinned preparations found that while cTnI-ND cardiac muscle shows a resting SL–resting tension relationship similar to WT control, cTnI-ND significantly increases myofibril Ca2+ sensitivity to resting tension. The results demonstrate that restrictive N-terminal deletion of cTnI enhances Frank-Starling response by increasing myofilament sensitivity to resting tension rather than directly depending on SL. This novel function of cTnI regulation suggests a myofilament approach to utilizing Frank-Starling mechanism for the treatment of heart failure, especially diastolic failure where ventricular filling is limited.
Sub-aperture SAR imaging with uncertainty quantification
Authors: Churchill Victor , Gelb Anne
Published: March 2023

In the problem of spotlight mode airborne synthetic aperture radar (SAR) image formation, it is well-known that data collected over a wide azimuthal angle violate the isotropic scattering property typically assumed. Many techniques have been proposed to account for this issue, including both full-aperture and sub-aperture methods based on filtering, regularized least squares, and Bayesian methods. A full-aperture method that uses a hierarchical Bayesian prior to incorporate appropriate speckle modeling and reduction was recently introduced to produce samples of the posterior density rather than a single image estimate. This uncertainty quantification information is more robust as it can generate a variety of statistics for the scene. As proposed, the method was not well-suited for large problems, however, as the sampling was inefficient. Moreover, the method was not explicitly designed to mitigate the effects of the faulty isotropic scattering assumption. In this work we therefore propose a new sub-aperture SAR imaging method that uses a sparse Bayesian learning-type algorithm to more efficiently produce approximate posterior densities for each sub-aperture window. These estimates may be useful in and of themselves, or when of interest, the statistics from these distributions can be combined to form a composite image. Furthermore, unlike the often-employed

ℓ
p

-regularized least squares methods, no user-defined parameters are required. Application-specific adjustments are made to reduce the typically burdensome runtime and storage requirements so that appropriately large images can be generated. Finally, this paper focuses on incorporating these techniques into SAR image formation process, that is, for the problem starting with SAR phase history data, so that no additional processing errors are incurred. The advantage over existing SAR image formation methods are clearly presented with numerical experiments using real-world data.
Enhanced spin Hall effect of light in the PT-symmetric trilayer structure containing epsilon-near-zero materials
Authors: Song Yifei , Shu Yetao , Jiang Ting , Liu Jing , Luo Zhaoming
Published: March 2023

We systematically study the spin Hall effect of light (SHEL) in the parity-time (PT)-symmetric trilayer structure containing epsilon-near-zero (ENZ) materials, and design a high sensitivity refractive index sensor with an adjustable sensing range. It is revealed that the SHEL shift in the PT-symmetric trilayer structure is clearly enhanced, which is two orders of magnitude larger than that in the conventional sandwich structure containing ENZ materials. The enhancement of the SHEL shift is attributed to the fact that the change of reflection coefficient induced by the quasi-bound states in the continuum (quasi-BIC) in the former structure is smoother than that induced by the bound states in the continuum in the latter structure. It is further found that when the refractive index of the interlayer dielectric in the PT-symmetric structure is fixed, the SHEL shift is significantly enhanced near the quasi-BIC resonance angle determined by the gain-loss coefficient. Meanwhile, the SHEL shift enhanced by excitation of quasi-BIC is very sensitive to the gain-loss coefficient and the refractive index of the interlayer dielectric. Finally, we design a high sensitivity refractive index sensor with an adjustable sensing range based on the quasi-BIC-enhanced SHEL shift. These studies provide a pathway to enhance the SHEL and may open avenues for the application of optical sensors.
High-field magnetization and electronic spin resonance study in the twisted honeycomb lattice α-Mn2V2O7
Authors: Chen R , Hu H J , Qu Z , Song Y R , Lei Q K , Liu C B , Tang Y S , Wang C L , He Z Z , Ouyang Z W , Zhang K , Qiu Y , Dong C , Wang J F
Published: March 2023

We report the single-crystal growth of Mn2V2O7and the results of magnetic susceptibility, high-field magnetization up to 55 T and high-frequency electric spin resonance (ESR) measurements for its low-temperatureαphase. Two antiferromagnetic (AFM) ordering at 17.5 K and 3 K and obvious magnetic anisotropy are observed inα-Mn2V2O7upon cooling. In pulsed high magnetic fields, the compound reaches the saturation magnetic moment of ∼10.5μBfor each molecular formula at around 45 T after two undergoing AFM phase transitions atHc1≈ 16 T,Hc2≈ 34.5 T forH//[11ˉ0] andHsf1= 2.5 T,Hsf2= 7 T forH//[001]. In these two directions, two and seven resonance modes are detected by ESR spectroscopy, respectively. Theω1andω2modes ofH//[11ˉ0] can be well described by two-sublattice AFM resonance mode with two zero-field gaps at 94.51 GHz and 169.28 GHz, indicating a hard-axis feature. The seven modes forH//[001] are partially separated by the critical fields ofHsf1andHsf2, displaying the two signs of spin-flop transition. The fittings ofωc1andωc2modes yield zero-field gaps at 69.50 GHz and 84.73 GHz forH//[001], confirming the axis-type anisotropy. The saturated moment and gyromagnetic ratio indicate the Mn2+ion inα-Mn2V2O7is in a high spin state with orbital moment completely quenched. A quasi-one-dimensional magnetism with a zig-zag-chain spin configuration is suggested inα-Mn2V2O7, due to the special neighbor interactions caused by a distorted network structure with honeycomb layer.
Vortex-bound solitons in topological superfluid 3He
Authors: Mäkinen J T , Zhang K , Eltsov V B
Published: March 2023

The different superfluid phases of 3He are described by p-wave order parameters that include anisotropy axes both in the orbital and spin spaces. The anisotropy axes characterize the broken symmetries in these macroscopically coherent quantum many-body systems. The systems’ free energy has several degenerate minima for certain orientations of the anisotropy axes. As a result, spatial variation of the order parameter between two such regions, settled in different energy minima, forms a topological soliton. Such solitons can terminate in the bulk liquid, where the termination line forms a vortex with trapped circulation of mass and spin superfluid currents. Here we discuss possible soliton-vortex structures based on the symmetry and topology arguments and focus on the three structures observed in experiments: solitons bounded by spin-mass vortices in the B phase, solitons bounded by half-quantum vortices (HQVs) in the polar and polar-distorted A phases, and the composite defect formed by a half-quantum vortex, soliton and the Kibble-Lazarides-Shafi wall in the polar-distorted B phase. The observations are based on nuclear magnetic resonance (NMR) techniques and are of three types: first, solitons can form a potential well for trapped spin waves, observed as an extra peak in the NMR spectrum at shifted frequency; second, they can increase the relaxation rate of the NMR spin precession; lastly, the soliton can present the boundary conditions for the anisotropy axes in bulk, modifying the bulk NMR signal. Owing to solitons’ prominent NMR signatures and the ability to manipulate their structure with external magnetic field, solitons have become an important tool for probing and controlling the structure and dynamics of superfluid 3He, in particular HQVs with core-bound Majorana modes.
Fast near-infrared photodetectors from p-type SnSe nanoribbons
Authors: Li Long , Fang Suhui , Yu Ranran , Chen Ruoling , Wang Hailu , Gao Xiaofeng , Zha Wenjing , Yu Xiangxiang , Jiang Long , Zhu Desheng , Xiong Yan , Liao Yan-Hua , Zheng Dingshan , Yang Wen-Xing , Miao Jinshui
Published: March 2023

Low-dimensional tin selenide nanoribbons (SnSe NRs) show a wide range of applications in optoelectronics fields such as optical switches, photodetectors, and photovoltaic devices due to the suitable band gap, strong light–matter interaction, and high carrier mobility. However, it is still challenging to grow high-quality SnSe NRs for high-performance photodetectors so far. In this work, we successfully synthesized high-quality p-type SnSe NRs by chemical vapor deposition and then fabricated near-infrared photodetectors. The SnSe NR photodetectors show a high responsivity of 376.71 A W−1, external quantum efficiency of 5.65 × 104%, and detectivity of 8.66 × 1011 Jones. In addition, the devices show a fast response time with rise and fall time of up to 43 μs and 57 μs, respectively. Furthermore, the spatially resolved scanning photocurrent mapping shows very strong photocurrent at the metal-semiconductor contact regions, as well as fast generation-recombination photocurrent signals. This work demonstrated that p-type SnSe NRs are promising material candidates for broad-spectrum and fast-response optoelectronic devices.
In situ growth strategy to construct perovskite quantum dot@covalent organic framework composites with enhanced water stability
Authors: Zhang Hongyan , He Xiaoxiong , Wang Hao , Chen Liangjun , Xu Gaopeng , Zhang Nan , Qu Kang , He Qingquan , Peng Yongwu , Pan Jun
Published: March 2023

Metal halide perovskite quantum dots (QDs) have excellent optoelectronic properties; however, their poor stability under water or thermal conditions remains an obstacle to commercialization. Here, we used a carboxyl functional group (−COOH) to enhance the ability of a covalent organic framework (COF) to adsorb lead ions and grow CH3NH3PbBr3 (MAPbBr3) QDs in situ into a mesoporous carboxyl-functionalized COF to construct MAPbBr3 QDs@COF core–shell-like composites to improve the stability of perovskites. Owing to the protection of the COF, the as-prepared composites exhibited enhanced water stability, and the characteristic fluorescence was maintained for more than 15 d. These MAPbBr3 QDs@COF composites can be used to fabricate white light-emitting diodes with a color comparable to natural white emission. This work demonstrates the importance of functional groups for the in situ growth of perovskite QDs, and coating with a porous structure is an effective way to improve the stability of metal halide perovskites.
A study of indirect action’s impact on simulated neutron-induced DNA damage
Authors: Manalad James , Montgomery Logan , Kildea John
Published: March 2023

Objective. The risk of radiobiological stochastic effects associated with neutrons is strongly energy dependent. Recent Monte Carlo studies simulating neutron-irradiated nuclear DNA have demonstrated that this energy dependence is correlated with the relative biological effectiveness (RBE) of neutrons to inflict DNA damage clusters that contain difficult-to-repair double-strand breaks. However, these previous investigations were either limited to modeling direct radiation action or considered the effects of both direct and indirect action together without distinguishing between the two. In this study, we aimed to quantify the influence of indirect action in neutron irradiation scenarios and acquire novel estimations of the energy-dependent neutron RBE for inducing DNA damage clusters due to both direct and indirect action. Approach. We explored the role of indirect action in neutron-induced DNA damage by integrating a validated indirect action model into our existing simulation pipeline. Using this pipeline, we performed track-structure simulations of monoenergetic neutron irradiations (1 eV to 10 MeV) in a nuclear DNA model and analyzed the resulting simple and clustered DNA lesions. We repeated the irradiation simulations for 250 keV x-rays that acted as our reference radiation. Main results. Including indirect action significantly increased the occurrence of DNA lesions. We found that indirect action tends to amplify the damage due to direct action by inducing DNA lesions in the vicinity of directly-induced lesions, resulting in additional and larger damage clusters. Our neutron RBE results are qualitatively similar to but lower in magnitude than the established radiation protection factors and the results of previous similar investigations, due to the greater relative impact of indirect action in photon-induced damage than in neutron-induced damage. Significance. Although our model for neutron-induced DNA damage has some important limitations, our findings suggest that the energy-dependent risk of neutron-induced stochastic effects may not be completely modeled alone by the relative potential of neutrons to inflict clustered lesions via direct and indirect action in DNA damage.
A frequency up-conversion rotational energy harvester with auxetic structures for high power output
Authors: Chen Keyu , Fang Shitong , Lai Zhihui , Cao Junyi , Liao Wei-Hsin
Published: March 2023

Rotational energy harvesters (REHs) have been explored to substitute conventional batteries for small electronic sensors. However, there still exists a challenge for REHs to scavenge sufficient energy under low-rotational-frequency excitations. In this paper, we propose a plucking REH with auxetic structures, which utilizes the frequency up-conversion and auxetic structures to enhance the power output of the rotational energy harvesting under low-rotational-frequency excitations. Finite element simulation is performed to analyze the performance of the proposed REH. The simulation results match well with the experimental ones. When the magnet distance is set to be 2.5 mm, the maximum power output of the auxetic plucking REH (APREH) is found to be 1.43 mW at 1.1 Hz, which is increased by 686% compared with the conventional plain plucking REH. In addition, compared with typical plucking REHs, the proposed APREH achieves the highest power output under low-rotational-frequency excitations, which validates the advantage of adopting auxetic structures in plucking REHs.
Exceptional-point sensing with a quantum interferometer
Authors: Wong Wai Chun , Li Jensen
Published: March 2023

Recently, multiple studies have suggested that exceptional points (EPs) in lossless nonlinear optical systems can minimize quantum noise arising from the material gain and loss in conventional non-Hermitian systems, offering the possibility of quantum EP sensing. Meanwhile, nonlinear SU(1,1) interferometers have been established as useful in sensing due to their reduced quantum noise. In this work, we demonstrate the existence of EPs in a dual-beam SU(1,1) interferometer with two nonlinear parametric amplifiers. Our analysis of the input-output matrix in terms of joint quadrature amplitudes shows that EPs can be linked to both high signal, through a zero matrix element, and low noise, through noise preservation, in sensing by selecting an appropriate operation gauge of the quadrature amplitudes. Additionally, for a multistage SU(1,1) interferometer, EPs of the overall input-output matrix form multiple bands of high signal-to-noise ratio (SNR) which further separate into two phases indicated by the EPs of the transfer matrix of a repeating unit. Our investigations demonstrate the significance of quantum EPs in quantum interferometer sensing and broaden the operating regimes from diabolical points in some of the conventional SU(1,1) interferometers to EPs while still maintaining a high SNR.
ESR-PINNs: Physics-informed neural networks with expansion-shrinkage resampling selection strategies
Authors: Liu Jianan , Hou Qingzhi , Wei Jianguo , Sun Zewei
Published: March 2023

Neural network methods have been widely used in many fields of scientific research with the rapid increase of computing power. The physics-informed neural networks (PINNs) have received much attention as a major breakthrough in solving partial differential equations using neural networks. In this paper, a resampling technique based on the expansion-shrinkage point (ESP) selection strategy is developed to dynamically modify the distribution of training points in accordance with the performance of the neural networks. In this new approach both training sites with slight changes in residual values and training points with large residuals are taken into account. In order to make the distribution of training points more uniform, the concept of continuity is further introduced and incorporated. This method successfully addresses the issue that the neural network becomes ill or even crashes due to the extensive alteration of training point distribution. The effectiveness of the improved physics-informed neural networks with expansion-shrinkage resampling is demonstrated through a series of numerical experiments.
Versatile Link+ transceiver production
Authors: Soós C. , Bergin D.E. , Detraz S. , Lalović M. , Marcon L. , Olanterä L. , Prousalidi T. , Sandven U. , Scarcella C. , Sigaud C. , Troska J.
Published: March 2023

The Versatile Link+ project targeting the Phase 2 HL-LHC detector upgrades is entering the production phase. After several years of prototyping, the industrialisation of the Versatile Link+ Transceiver (VTRx+) was launched in 2021 and the production is scheduled to start in 2022. We describe the extensive qualification effort carried out and the quality assurance procedures put in place to monitor the manufacturing quality. We summarise the experience of the industrialisation and we present the plans for the production.
Rapid characterization of silicon photomultipliers for noble liquid experiments
Authors: Chana B. , Mahtab M. , Retière F. , Viel S.
Published: March 2023

Silicon photomultipliers (SiPMs) are emerging as the photodetector technology to be used in upcoming noble liquid experiments. Newly developed SiPMs sensitive to vacuum ultraviolet (VUV) light will be directly used for the readout of scintillation photons (λ = 175 nm) from liquid xenon in future tonne-scale experiments, such as nEXO, searching for neutrinoless double beta decay in 136Xe. In this research project, VUV-SiPMs from two different vendors are characterized using current–voltage (IV) and pulse-level measurements performed at TRIUMF, from room temperature to liquid xenon temperature. These data are analysed to extract the SiPM’s features such as breakdown voltage, gain, crosstalk, afterpulsing and dark noise rates. The IV and pulse-level results are compared. A method is proposed for rapid quality control of large numbers of SiPM using IV measurements.
The design and test results of A Giga-Bit Cable Receiver (GBCR) for the ATLAS Inner Tracker Pixel Detector
Authors: Zhang L. , Gong D. , Liu T. , Chen C. , Deng B. , Hou S. , Huang G. , Huang X. , Liu C. , Moreira P. , Sun Q. , Sun X. , Kulis S. , Ye J. , Zhang W.
Published: March 2023

This paper presents the design and test results of a Gigabit Cable Receiver ASIC called GBCR for the HL-LHC upgrade of the ATLAS Inner Tracker (ITk) pixel detector. Three prototypes (GBCR1, GBCR2, and GBCR3) have been designed in the CERN-identified 65 nm CMOS technology. GBCR receives seven (GBCR2) or six (GBCR3) channels (RX) each at 1.28 Gbps from the front-end readout chip RD53B via flex cables up to 1 meter and Twinax cables up to 5 meters and sends the equalized and retimed signals to lpGBT. Both GBCR2 and GBCR3 ASICs have two transmitting channels (TX) that pre-emphasize the signals from lpGBT before sending them to RD53B through the same cables. No Single-Event Upset (SEU) is observed in any tested channels of GBCR2 in a 400 MeV proton beam. The extrapolated bit error rate for the future HL-LHC application is below 8 × 10−16, significantly below the specified BER criterion. GBCR3 is designed to improve the immunity to single-event-upset by applying the Triple Modular Redundancy (TMR) technology to all RX channels. The retimed signals from GBCR3 have less total jitter than those from GBCR2 (35 ps versus 79 ps). Each receiver channel of GBCR3 consumes 75% more power than that of GBCR2.
Improving reflexive surfaces efficiency with genetic algorithms
Authors: Steklain A. , Adames M. , Ganacim F.
Published: March 2023

We propose using a Genetic Algorithm to improve the
efficiency of reflexive surfaces in devices where the receiver's
position is different from the classic parabolic antenna. With this
technique, we show that we can improve the efficiency of the ARAPUCA
photodetector.
The importance of interactions between snow, permafrost and vegetation dynamics in affecting terrestrial carbon balance in circumpolar regions
Authors: Xu Yiming , Zhuang Qianlai
Published: March 2023

Permafrost dynamics can drastically affect vegetation and soil carbon dynamics in northern high latitudes. Vegetation has significant influences on the energy balance of soil surface by impacting the short-wave radiation, long-wave radiation and surface sensible heat flux, affecting soil thermal dynamics, in turn, inducing vegetation shift, affecting carbon cycling. During winter, snow can also significantly impact soil temperature due to its insulative effect. However, these processes have not been fully modeled to date. To quantify the interactions between vegetation, snow, and soil thermal dynamics and their impacts on carbon dynamics over the circumpolar region (45–90° N), we revise a sophisticated ecosystem model to improve simulations of soil temperature profile and their influences on vegetation, ecosystem carbon pools and fluxes. We find that, with warmer soil temperature in winter and cooler soil temperature in summer simulated with the revised model considering vegetation shift and snow effects, the region will release 1.54 Pg C/year to the atmosphere for present-day and 66.77–87.95 Pg C in 2022–2100. The canopy effects due to vegetation shift, however, will get more carbon sequestered into the ecosystem at 1.00 Pg C/year for present day and 36.09–44.32 Pg C/year in 2022–2100. This study highlights the importance to consider the interactions between snow, vegetation shift and soil thermal dynamics in simulating carbon dynamics in the region.