bluuebunny/crossref_metadata_2025 huggingface dataset:
Turnaround density evolution encodes cosmology in simulations
Authors: Korkidis Giorgos , Pavlidou Vasiliki , Tassis Konstantinos
Published: April 2023

Context. The mean matter density within the turnaround radius, which is the boundary that separates a nonexpanding structure from the Hubble flow, was recently proposed as a novel cosmological probe. According to the spherical collapse model, the evolution with cosmic time of this turnaround density, ρta(z), can be used to determine both Ωm and ΩΛ, independently of any other currently used probe. The properties of ρta predicted by the spherical collapse model (universality for clusters of any mass, value) were also shown to persist in the presence of full three-dimensional effects in ΛCDM N-body cosmological simulations when considering galaxy clusters at the present time, z = 0. However, a small offset was discovered between the spherical-collapse prediction of the value of ρta at z = 0 and its value measured in simulations.

Aims. In this letter, we explore whether this offset evolves with cosmic time; whether it differs in different cosmologies; whether its origin can be confidently identified; and whether it can be corrected. Specifically, we aim to examine whether the evolution of ρta can be used to distinguish between simulated universes with and without a cosmological constant.

Methods. We used N-body simulations with different cosmological parameters to trace the evolution of the turnaround density ρta with cosmic time for the largest dark matter halos in the simulated boxes. To this end, we analyzed snapshots of these simulations at various redshifts, and we used radial velocity profiles to identify the turnaround radius within which we measured ρta.

Results. We found an offset between the prediction of the spherical collapse model for ρta and its measured value from simulations. The offset evolves slightly with redshift. This offset correlates strongly with the deviation from spherical symmetry of the dark matter halo distribution inside and outside of the turnaround radius. We used an appropriate metric to quantify deviations in the environment of a structure from spherical symmetry. We found that using this metric, we can construct a sphericity-selected sample of halos for which the offset of ρta from the spherical collapse prediction is zero, independently of redshift and cosmology.

Conclusions. We found that a sphericity-selected halo sample allows us to recover the simulated cosmology, and we conclude that the turnaround density evolution indeed encodes the cosmology in N-body simulations.
Solar energetic particle event onsets at different heliolongitudes: The effect of turbulence in Parker spiral geometry
Authors: Laitinen T. , Dalla S. , Waterfall C. O. G. , Hutchinson A.
Published: April 2023

Context.Solar energetic particles (SEPs), accelerated during solar eruptions, are observed to rapidly reach a wide heliolongitudinal range in the interplanetary space. Turbulence-associated SEP propagation across the mean Parker spiral direction has been suggested to contribute to this phenomenon.

Aims.We study SEP propagation in turbulent magnetic fields to evaluate SEP spatial distribution in the heliosphere, their path lengths, and the overall evolution of SEP intensities at 1 au.

Methods.We use full-orbit test particle simulations of 100-MeV protons in a novel analytic model of the turbulent heliospheric magnetic field, where the turbulence is dominated by modes that are transverse and 2D with respect to the Parker spiral direction.

Results.We find that by propagating along meandering field lines, SEPs reach a 60°-wide heliolongitudinal range at 1 au within an hour of their injection for the turbulence parameters considered. The SEP onset times are asymmetric with respect to the location connected to the source along the Parker spiral, with the earliest arrival times being 15° westwards from the well-connected Parker spiral longitude. The inferred path length of the first arriving particles is 1.5−1.8 au within 30° of the well-connected longitude; 20−30% longer than the length of the random-walking field lines, increasing monotonously at longitudes further away; and 30−50% longer than the Parker spiral. The global maximum intensity is reached 15° west from the well-connected longitude an hour after the SEP injection. Subsequently, the SEP distribution broadens, consistent with diffusive spreading of SEPs across the field lines.

Conclusions.Our results indicate that magnetic field line meandering can explain rapid access of SEPs to wide longitudinal ranges, as well as several other features of SEP event intensity evolution.
Accurate calibration of optical tweezers close to a glass surface using interference rings in backscattered light
Authors: Gillant Flavie , Moreau Julien , Richly Maximilian U. , Alexandrou Antigoni , Perronet Karen , Westbrook Nathalie
Published: April 2023

Mechanical forces play an important role in the behaviour of cells, from differentiation to migration and the development of diseases. Optical tweezers provide a quantitative tool to study these forces and must be combined with other tools, such as phase contrast and fluorescence microscopy. Detecting the retro-reflected trap beam is a convenient way to monitor the force applied by optical tweezers, while freeing top access to the sample. Accurate in situ calibration is required especially for single cells close to a surface where viscosity varies rapidly with height. Here, we take advantage of the well contrasted interference rings in the back focal plane of the objective to find the height of a trapped bead above a cover slip. We thus map the viscous drag dependence close to the surface and find agreement between four different measurement techniques for the trap stiffness down to 2 μm above the surface. Combining this detection scheme with phase contrast microscopy, we show that the phase ring in the back focal plane of the objective must be deported in a conjugate plane on the imaging path. This simplifies implementation of optical tweezers in combination with other techniques for biomechanical studies.
Effect of Mo content on impact toughness of CGHAZ in offshore engineering steels at different low temperatures
Authors: Du Hailong , Zhang Yinhui , Zhang Yuqi , Yang Jian
Published: April 2023

The effect of Mo content on impact toughness of the coarse-grained heat-affected zone (CGHAZ) in 420 MPa offshore engineering steels after 15 kJ/cm welding simulations is studied at low temperatures of −40, −60 and −80 °C. With increasing Mo content from 0.08 to 0.16 wt.%, the average size of the prior austenite grain in the CGHAZ is decreased from 150 to 70 µm, which mainly consists of lath bainite (LB). The fraction of high-angle grain boundaries (HAGBs) increases from 45.3% to 58.2%. The EBSD characterizations on the propagation and deflection of the main and secondary cracks in the CGHAZ indicate that the cleavage planes of the main crack mainly comprise of {100}, {110} and {112}. The way of fracture is changed from ductile fracture to quasi-cleavage fracture and cleavage fracture with decreasing the impact test temperature. As the Mo content is increased from 0.08 to 0.16 wt.%, the impact toughness values at −40, −60 and −80 °C are changed from 137, 101 and 40 J to 195, 117 and 88 J, respectively. With increasing the Mo content, the absorbed energies of the CGHAZ is improved because the sizes of PAG (Prior Austenite Grain) and LB are refined, and the fraction of HAGBs is increased to provide larger resistance for propagation of crack in CGHAZ.
U-Statistics on bipartite exchangeable networks
Authors: Le Minh Tâm
Published: April 2023

Bipartite networks with exchangeable nodes can be represented by row-column exchangeable matrices. A quadruplet is a submatrix of size 2 × 2. A quadruplet U-statistic is the average of a function on a quadruplet over all the quadruplets of a matrix. We prove several asymptotic results for quadruplet U-statistics on row-column exchangeable matrices, including a weak convergence result in the general case and a central limit theorem when the matrix is also dissociated. These results are applied to statistical inference in network analysis. We suggest a method to perform parameter estimation, network comparison and motifs count for a particular family of row-column exchangeable network models: the bipartite expected degree distribution (BEDD) models. These applications are illustrated by simulations.
Screening for At-Risk Nonalcoholic Fatty Liver Disease in the Primary Care Setting
Authors: Urias Esteban , Chen Vincent L.
Published: April 2023

While nonalcoholic fatty liver disease is a leading cause of end-stage liver disease, most patients with nonalcoholic fatty liver disease do not develop cirrhosis and its complications. Therefore, risk stratification using inexpensive, noninvasive screening modalities is critical to avoid overdiagnosis and overtreatment of a large proportion of the population. In this review, we discuss the data supporting screening and current professional society recommendations on this topic. Screening for at-risk nonalcoholic fatty liver disease is recommended in patients with risk factors including diabetes, the metabolic syndrome, hepatic steatosis, and elevated aminotransferases. Screening typically consists of noninvasive testing using serum biomarkers followed by elastography using specialized imaging modalities. This sequential screening approach accurately identifies both high- and low-risk patients and is cost-effective when applied to at-risk populations. In conclusion, screening for advanced nonalcoholic fatty liver disease in the primary care setting is a crucial part of identifying high-risk patients who may benefit from aggressive intervention while avoiding overtreatment of patients at low risk of liver-related complications.
Evaluation and Comparison of Respiratory Muscular Strength, Functionality, and Pelvic Floor in the Immediate Postpartum of Normal and Cesarean Birth
Authors: Rosa Carolina Martins da , Dockhorn Thariny Huesken , Cardoso Juliana Rezende , Forgiarini Soraia Genebra Ibrahim , Junior Luiz Alberto Forgiarini , Cordeiro André Luiz Lisboa
Published: April 2023

Objective: To evaluate and compare peripheral, pelvic floor, respiratory muscle strength, and functionality in the immediate puerperium of normal delivery and cesarean section.

Methods: This is a cross-sectional study that verified respiratory, pelvic floor, peripheral, and functional muscle strength through manovacuometry, pelvic floor functional assessment (PFF), dynamometry, and the Time Up and Go (TUG) test, respectively. The groups were divided according to the type of delivery, into a cesarean section group and a normal parturition group.

Results: The sample was composed of 72 postpartum puerperae, 36 of normal parturition, and 36 of cesarean section, evaluated before hospital discharge, mean age ranged from 25.56 ± 6.28 and 28.57 ± 6.47 years in puerperae of normal parturition and cesarean section respectively. Cesarean showed higher pelvic floor strength (PFF) compared to normal parturition (p < 0.002), but puerperae from normal delivery showed better functionality (p < 0.001). As for peripheral muscle strength and respiratory muscle strength, there was no significance when comparing the types of parturirion.

Conclusion: There is a reduction in pelvic muscle strength in puerperae of normal delivery and a decrease in functionality in puerperae of cesarean section.
The risk-return tradeoff: are sustainable investors compensated adequately?
Authors: Bannier Christina E. , Bofinger Yannik , Rock Björn
Published: April 2023

We investigate the returns from investing according to corporate social responsibility (CSR) criteria using factor model estimations for a large sample of U.S. firms over the period 2003–2017. To identify the CSR intensity that allows investors to optimize their portfolio returns for a given amount of risk, we relate factor-adjusted portfolio returns to a variety of risk measures. This consideration is important as equity risks have been shown to significantly decrease with CSR. Surprisingly, our results indicate that the lowest CSR-rated portfolios are able to outperform their higher CSR-rated counterparts: Not only do they show higher factor-adjusted returns but they also deliver higher return-to-risk ratios. This indicates that equity returns in our sample decrease even more strongly than the corresponding risks with rising CSR activity.
Gifts, growing, and love: A qualitative analysis of children’s literature depicting breastfeeding
Authors: Bianca Kelsey Palmer
Published: April 2023

Children’s literature on the topic of breastfeeding is a niche form of media that has the potential to present breastfeeding in a different light because of a difference in audience and intent, but this media form is understudied. The aim of this study was to explore the portrayal of breastfeeding in English language children’s literature published between 1985 and 2020. This cross-sectional qualitative study explored the written and visual content of children’s literature on the topic of breastfeeding. This qualitative study utilized content analysis to explore 49 children’s books that depict breastfeeding as a major theme or story. Children’s books depict breastfeeding as an act of love that confers benefits beyond nutrition including being a symbolic gift, and conferring growth, and love. Breastfeeding is presented in these books by teaching how mammals feed their young or by teaching children about the function of breasts. These books also often include information for parents. Children’s literature depicting breastfeeding provides a unique avenue for the dissemination of breastfeeding resources and information. This research can inform lactation education practices in healthcare settings by normalizing breastfeeding.
Interdisciplinary opportunities to advance nanofluidics
Authors: Thompson Avery
Published: April 2023

Interfacing electronic, ionic, and fluidic systems at the nanoscale requires a deeper understanding of nanofluidic processes, which could be gained using tools from other disciplines.
Reaction extent or advancement of reaction: A definition for complex chemical reactions
Authors: Gáspár V. , Tóth J.
Published: April 2023

The concept of reaction extent (the progress of a reaction, advancement of the reaction, conversion, etc.) was introduced around 100 years ago. Most of the literature provides a definition for the exceptional case of a single reaction step or gives an implicit definition that cannot be made explicit. There are views that the reaction extent somehow has to tend to 1 when the reaction goes to completion as time tends to infinity. However, there is no agreement on which function should tend to 1. Starting from the standard definition by IUPAC and following the classical works by De Donder, Aris, and Croce, we extend the definition of the reaction extent for an arbitrary number of species and reaction steps. The new general, explicit definition is also valid for non-mass action kinetics. We also studied the mathematical properties (evolution equation, continuity, monotony, differentiability, etc.) of the defined quantity, connecting them to the formalism of modern reaction kinetics. Our approach tries to adhere to the customs of chemists and be mathematically correct simultaneously. To make the exposition easy to understand, we use simple chemical examples and many figures, throughout. We also show how to apply this concept to exotic reactions: reactions with more than one stationary state, oscillatory reactions, and reactions showing chaotic behavior. The main advantage of the new definition of reaction extent is that by knowing the kinetic model of a reacting system one can now calculate not only the time evolution of the concentration of each reacting species but also the number of occurrences of the individual reaction events.
Determining the optimal operation and maintenance contract period of PV poverty alleviation projects based on real options and cooperative game: Evidence from rural China
Authors: Dai Qiyao , Ding Liping , Zhang Zumeng , Zhu Yuxuan , Shi Yin
Published: April 2023

China's photovoltaic poverty alleviation power stations (PPAPS) properly combine poverty alleviation and renewable power generation while also meeting rural energy demands. The fundamental problem is how to optimize the benefits of PPAPS during its limited lifetime. Using the post-operation of photovoltaic poverty alleviation power plants as a starting point, this paper proposes a model combining real option theory and cooperative game to determine the ideal contract period of service committed by the government to the operation and maintenance (O&M) company, thus providing a reference for both parties. The model's validity and applicability are verified by incorporating a PPAPS from Henan Province in China as an example; ultimately, the factors influencing the O&M contract period are ranked using the Sobol global sensitivity analysis. The results show that when the solar industry's environment is positive, the government is more inclined to sign long-term contracts with O&M companies. In contrast, the more the government invests in the facilities, the more likely both parties will sign short-term contracts. Furthermore, the O&M company's capital investment in the power station has a direct impact on the contract period. Finally, corresponding policy recommendations are proposed for future O&M contracts.
Numerical investigation of ejecta mass of twice-shocked liquid Sn
Authors: Wu Bao , He AnMin , Wang XinXin , Sun HaiQuan , Wang Pei
Published: April 2023

In this paper, we investigate the ejection production from twice-shocked Sn using molecular dynamic simulations in regimes where the metal undergoes complete shock melting after the first shock. A new description form of a bubble shape is proposed to fit the interface during the whole stage, which overcomes the inapplicability of the flycut profile in later stages. We then explore the ejection on second shock with the dimensionless intervals of ∼3.8 and ∼96 between the two shocks. Surprisingly, the results show that the ejecta model can well predict the second ejecta mass with a shock interval of ∼3.8 while far underestimated that with a shock interval of ∼96. We find that in the presence of the first ejecta, the high-speed secondary interface interacts with the low-speed first ejecta, resulting in the movement of liquid metals to the secondary ejecta, thereby promoting the increase of secondary ejecta mass. These findings are further validated by our smoothed particle hydrodynamics simulations at a macroscale.
Observation of magnetic-field-induced ferroelectricity in a compound CaFe3O(PO4)3
Authors: Voma U. K. , Shahee A. , Kim Kwang-Tak , Lee Jungwoo , Boya K. , Bhowal S. , Kim Kee Hoon , Koteswararao B.
Published: April 2023

Geometrically frustrated kagome materials reveal many novel states of matter ranging from quantum spin liquids to multiferroics. Herein, we study the compound CaFe3O(PO4)3, which has a quasi-two-dimensional lattice of Fe3+ ions with spin S = 5/2. Electrical and magnetic properties have been investigated on polycrystalline specimens of CaFe3O(PO4)3 using magnetization, pyroelectric, and magnetoelectric current measurements. The system undergoes a weak ferromagnetic-type ordering at TC1 ∼ 19.5 K, followed by another transition at TC2 ∼ 9 K. While no ferroelectric polarization (P) is observed at a zero magnetic field (H), the applied H induces P below TC2. At the temperature of 2.5 K, P starts to increase above H of 1 T, shows a maximum value at 3.15 T, and then decreases at higher H regions. The observed results suggest that CaFe3O(PO4)3 should be a magnetic-field-induced ferroelectric compound with frustrated magnetic couplings.
A novel high-current, high-resolution, low-kinetic-energy electron source for inverse photoemission spectroscopy
Authors: Ibach Harald , Sato Haruki , Kubo Mihiro , Tautz F. Stefan , Yoshida Hiroyuki , Bocquet François C.
Published: April 2023

A high-current electron source for inverse photoemission spectroscopy is described. The source comprises a thermal cathode electron emission system, an electrostatic deflector-monochromator, and a lens system for variable kinetic energy (1.6–20 eV) at the target. When scaled to the energy resolution, the electron current is an order of magnitude higher than that of previously described electron sources developed in the context of electron energy loss spectroscopy. Surprisingly, the experimentally measured energy resolution turned out to be significantly better than calculated by standard programs, which include the electron–electron repulsion in the continuum approximation. The achieved currents are also significantly higher than predicted. We attribute this “inverse Boersch-effect” to a mechanism of velocity selection in the forward direction by binary electron–electron collisions.
A Z2 invariant for chiral and particle–hole symmetric topological chains
Authors: Monaco Domenico , Peluso Gabriele
Published: April 2023

We define a Z2-valued topological and gauge invariant associated with any one-dimensional, translation-invariant topological insulator that satisfies either particle–hole symmetry or chiral symmetry. The invariant can be computed from the Berry phase associated with a suitable basis of Bloch functions that is compatible with the symmetries. We compute the invariant in the Su–Schrieffer–Heeger model for chiral symmetric insulators and in the Kitaev model for particle–hole symmetric insulators. We show that in both cases, the Z2 invariant predicts the existence of zero-energy boundary states for the corresponding truncated models.
Application of robotic lower limb orthosis for people with lower limb dysfunction
Authors: Yang Shuo , Huang Xin , Zhou Jin-man , Xue Qiang
Published: April 2023

Due to the aging of the population or diseases, the number of patients with lower limb disorders has increased, causing social concern. Scholars have designed and developed advanced robotic lower limb orthoses, which can guide patients to perform reasonable rehabilitation training with correct limb postures, enhance their daily life participation and quality of life, and help them recover quickly. In recent years, a large number of new and advanced orthopedic equipment have been developed, which require a systematic summary analysis and comparison. This article reviewed typical newly developed, robotic lower limb orthoses and their use effects, as well as the advanced theories and technologies for their applications, and systematically discussed the problems in the research, design, testing, use, and popularization of robotic lower limb orthoses, and predicted their development direction in the future research and design, to enhance the reliability, convenience, and protection functions of orthotic equipment, make its functions closer to life, and give full play to the initiative of patients in the process of rehabilitation training, and reduce costs. Robotic lower limb orthoses is poised for even greater success and development in the future.
Thermal stress characteristics of monocrystalline silicon induced by ns pulse laser under auxiliary heating
Authors: Zeng Jiaming , Pan Yansong , Zhang Xue , Xiang Yunfeng , Li Changli
Published: April 2023

Aiming at the problems of unsmooth notch and even crack caused by thermal stress in the laser processing of monocrystalline silicon, the temperature and thermal stress under auxiliary heating (AH) induced by the ns pulse laser (NPL) and their distribution characteristics are studied. Based on the theory of heat conduction and elastic–plastic mechanics, a two-dimensional axisymmetric geometric model for the temperature and thermal stress distribution of monocrystalline silicon irradiated by the NPL under AH is established, and the effect of AH on laser-induced temperature and thermal stress field is calculated and analyzed. The results show that the temperature of monocrystalline silicon irradiated by the NPL increases over auxiliary heating temperature (AHT), but it is not a simple superposition between the AHT and the temperature induced by the NPL, but the temperature change rate gradually decreases. When the temperature is lower than the target melting point, the thermal stress at the target surface is always negative as compressive stress, and the change law is the same as that of the temperature. When the temperature is more than the target melting point, the thermal stress in the melting zone is released immediately. The thermal stress decreases with the AHT increasing, and the change rate gradually decreases too. The negative effect of thermal stress can be overcome by using the correlation between temperature and thermal stress. Finally, an experiment was introduced to validate the theoretical model and calculation result preliminary. This study can provide a theoretical basis for the new technology of laser processing-monocrystalline silicon.
On the elastodynamic properties of octet truss-based architected metamaterials
Authors: Oudich Mourad , Huang Edward , Heo Hyeonu , Xu Zhenpeng , Cui Huachen , Gerard Nikhil JRK , Zheng Xiaoyu (Rayne) , Jing Yun
Published: April 2023

Architected metamaterials have emerged as a central topic in materials science and mechanics, thanks to the rapid development of additive manufacturing techniques, which have enabled artificial materials with outstanding mechanical properties. This Letter seeks to investigate the elastodynamic behavior of octet truss lattices as an important type of architected metamaterials for high effective strength and vibration shielding. We design, fabricate, and experimentally characterize three types of octet truss structures, including two homogenous structures with either thin or thick struts and one hybrid structure with alternating strut thickness. High elastic wave transmission rate is observed for the lattice with thick struts, while strong vibration mitigation is captured from the homogenous octet truss structure with thin struts as well as the hybrid octet truss lattice, though the underlying mechanisms for attenuation are fundamentally different (viscoelasticity induced dampening vs bandgaps). Compressional tests are also conducted to evaluate the effective stiffness of the three lattices. This study could open an avenue toward multifunctional architected metamaterials for vibration shielding with high mechanical strength.
Effect of coarse graining in water models for the study of kinetics and mechanisms of clathrate hydrates nucleation and growth
Authors: Lauricella Marco , Meloni Simone , Ciccotti Giovanni
Published: April 2023

Clathrate hydrates are crystalline inclusion compounds wherein a water framework encages small guest atoms/molecules within its cavities. Among the others, methane clathrates are the largest fossil fuel resource still available. They can also be used to safely transport gases and can also form spontaneously under suitable conditions plugging pipelines. Understanding the crystallization mechanism is very important, and given the impossibility of experimentally identifying the atomistic path, simulations played an important role in this field. Given the large computational cost of these simulations, in addition to all-atom force fields, scientists considered coarse-grained water models. Here, we have investigated the effect of coarse-graining, as implemented in the water model mW, on the crystallization characteristics of methane clathrate in comparison with the all-atom TIP4P force field. Our analyses revealed that although the characteristics directly depending on the energetics of the water models are well reproduced, dynamical properties are off by the orders of magnitude. Being crystallization a non-equilibrium process, the altered kinetics of the process results in different characteristics of crystalline nuclei. Both TIP4P and mW water models produce methane clathrate nuclei with some amount of the less stable (in the given thermodynamic conditions) structure II phase and an excess of pentagonal dodecahedral cages over the tetrakaidecahedral ones regarding the ideal ratio in structure I. However, the dependence of this excess on the methane concentration in solution is higher with the former water model, whereas with the latter, the methane concentration in solution dependence is reduced and within the statistical error.
Study of charge transport mechanism in Ba doped Sr2CrMoO6 double perovskite mixed ionic electronic conductor
Authors: Kumar Vivek , Saini Sudha , Maiti Tanmoy
Published: April 2023

In this work, the conduction mechanism in B a x S r 2 − x CrMo O 6 (0 ≤ x ≤ 0.3) double perovskite has been investigated using different techniques, such as universal dynamic response (UDR) and modulus spectroscopy. AC impedance spectroscopy has been studied in the frequency range of 0.3 Hz–5 MHz in a wide range of temperatures. It has been found that the conduction mechanism is thermally activated and frequency-dependent. The impedance fitting response to the microstructure reveals that grain boundaries are more resistive and capacitive than grains. Analysis of the complex modulus indicates that both short- and long-range charge carrier transport is responsible for conduction with non-Debye-type response in these oxides. The permittivity analysis indicates the existence of both universalities, near constant loss and UDR. Furthermore, from the Almond West power law, hopping frequency ( ω c) and activation energy E a c have been calculated. The relaxation time and DC conductivity are found to obey Barton Nakajima and Namikawa's relation. In addition, the Kramers–Kronig relation and conductivity scaling are discussed to validate the impedance data and provide insight into the conduction processes in this mixed ionic electronic conductor.
Microstructure enhancement of macroscopic flexoelectric behavior of THV/Al composites
Authors: Shin Ju Hwan (Jay) , Zaitzeff Mikel J. , Groven Lori J. , Zhou Min
Published: April 2023

Flexoelectricity is often studied at the macroscopic scale for energy conversion and harvesting. The fact that microstructural heterogeneities can have a profound impact on a material's flexoelectric response has been under-appreciated and largely unexplored. To capture the effects of microstructure on both the macroscopic flexoelectric behavior and the development of microscopic electric field that drives such microscale processes, we develop a computational framework that enables the quantification of how the microstructure can influence the flexoelectric behavior of heterogeneous materials. The specific material evaluated is a porous composite of tetrafluoroethylene-hexafluoropropylene-vinylidene fluoride polymer and aluminum (Al) particles. The models explicitly resolve the Al particles and voids within the microstructure. The focus of the analysis is on assessing the physical mechanisms that enhance the macroscopic flexoelectric output and determining the effective flexoelectric coefficient of the inhomogeneous material. The approach also allows the contributions of individual strain gradient components to the effective flexoelectric coefficient to be delineated and offers a method of determining the flexoelectric coefficients associated with individual strain gradient components using measurements of the macroscopic flexoelectric responses of microstructures with different concentrations of Al particles and voids. It is concluded that the enhancement of local strain gradients near the Al particles and voids and the activation of contributions from multiple strain gradient components are the primary mechanisms for the increase in the macroscopic flexoelectric output of the composites. The macroscopic flexoelectric coefficient under cantilever beam bending is found to rise linearly with the Al content, consistent with the experimental measurements.
Formation and evolution of coherent structures in 3D strongly turbulent magnetized plasmas
Authors: Vlahos Loukas , Isliker Heinz
Published: April 2023

We review the current literature on the formation of coherent structures (CoSs) in strongly turbulent 3D magnetized plasmas. CoSs [Current Sheets (CS), magnetic filaments, large amplitude magnetic disturbances, vortices, and shocklets] appear intermittently inside a turbulent plasma and are collectively the locus of magnetic energy transfer (dissipation) into particle kinetic energy, leading to heating and/or acceleration of the latter. CoSs and especially CSs are also evolving and fragmenting, becoming locally the source of new clusters of CoSs. Strong turbulence can be generated by the nonlinear coupling of large amplitude unstable plasma modes, by the explosive reorganization of large-scale magnetic fields, or by the fragmentation of CoSs. A small fraction of CSs inside a strongly turbulent plasma will end up reconnecting. Magnetic Reconnection (MR) is one of the potential forms of energy dissipation of a turbulent plasma. Analyzing the evolution of CSs and MR in isolation from the surrounding CoSs and plasma flows may be convenient for 2D numerical studies, but it is far from a realistic modeling of 3D astrophysical, space, and laboratory environments, where strong turbulence can be exited, such as in the solar wind, the solar atmosphere, solar flares and Coronal Mass Ejections, large-scale space and astrophysical shocks, the magnetosheath, the magnetotail, astrophysical jets, and Edge Localized Modes in confined laboratory plasmas (tokamaks).
Generalized plasma focus problem and its application to space propulsion
Authors: Auluck S. K. H.
Published: April 2023

Space propulsion is unique among many proposed applications of the dense plasma focus in being critically dependent on the availability of a scaling theory that is well-grounded in physics, in conformity with existing experimental knowledge and applicable to experimentally untested configurations. This paper derives such a first-principles-based scaling theory and illustrates its application to a novel space propulsion concept, where the plasma focus sheath is employed as a power density amplifying mechanism to transport electric energy from a capacitive storage to a current-driven fusion load. For this purpose, a Generalized Plasma Focus problem is introduced and formulated. It concerns a finite, axisymmetric plasma, driven through a neutral gas at supersonic speed over distances much larger than its typical gradient scale length by its azimuthal magnetic field while remaining connected with its pulse power source through suitable boundaries. The Gratton-Vargas equation is rederived from the scaling properties of the equations governing plasma dynamics and solved for algebraically defined initial (insulator) and boundary (anode) surfaces. Scaling relations for a new space propulsion concept are derived. This consists of a modified plasma focus with a tapered anode that transports current from a pulsed power source to a consumable portion of the anode in the form of a hypodermic needle tube continuously extruded along the axis of the device. When the tube is filled with deuterium, the device may serve as a small-scale version of magnetized liner inertial fusion (MAGLIF) that could avoid failure of neutron yield scaling in a conventional plasma focus.
Sinc flexure hinges
Authors: Wang Qiliang , Long Yiping , Wei Jianming
Published: April 2023

This paper proposes a new type of flexure hinge: the sinc flexure hinge. A theoretical compliance and precision factor model of the sinc flexure hinge is developed based on the transfer matrix method. The finite element simulation is carried out using ANSYS Workbench. The error between the modeling and simulation results obtained is less than 7.0%. The influence of structural parameters on the compliance, precision factor, and compliance–precision ratio is analyzed. The results show that the compliance and precision are contradictory and that the minimum thickness has the most significant influence on performance. Compared with the other seven types of flexure hinges, the sinc flexure hinge delivers a good overall performance. Finally, a sinc flexure hinge is machined and its compliance is measured. The error between the experimental and theoretical values is less than 7.6%. Both the simulation and experimental results verify the effectiveness of the model.
Research progress in the co-pyrolysis of renewable biomass with plastic wastes for the synergetic production of chemicals and biofuels: A review
Authors: Muniyappan Dineshkumar , Shrikar Banagiri , Azhagu Uthayakumar , K. M Meera Sheriffa Begum , M. Angkayarkan Vinayakaselvi , Ramanathan Anand
Published: April 2023

The quantity of plastic waste generated by the public has increased dramatically over the years. Biomass is an abundant and substantial energy resource found in diverse forms all over the planet. In this regard, the co-pyrolysis of plastic and biomass wastes is an attractive option to mitigate the issue of waste accumulation and viable fuel production. This review focuses on progress in waste disposal and energy generation through co-pyrolysis. The properties of common solid feedstock combinations are addressed with an emphasis on proximate analysis, elemental composition, and heating value. Subsequently, state-of-the-art kinetics is reviewed and compared for the efficacies of various kinetic models, which could be applied to understand decomposition mechanisms. The synergy between biomass and plastics was analyzed, and the impact of decomposition mechanisms on the bio-oil, char, and gas yield and composition was discussed. In addition, this study unveiled various reaction pathways for non-catalytic and catalytic co-pyrolysis. Finally, a summary of the economics in co-pyrolysis with knowledge gaps concerning waste management and energy production is addressed. The main goal of this review is to provide a feasible, practical pathway for clean and effective plastic waste disposal by using biomass waste to increase the synergistic effect.
Optimizing the sensitivity of high repetition rate broadband transient optical spectroscopy with modified shot-to-shot detection
Authors: Hall Siedah J. , Budden Peter J. , Zats Anne , Sfeir Matthew Y.
Published: April 2023

A major limitation of transient optical spectroscopy is that relatively high laser fluences are required to enable broadband, multichannel detection with acceptable signal-to-noise levels. Under typical experimental conditions, many condensed phase and nanoscale materials exhibit fluence-dependent dynamics, including higher order effects such as carrier–carrier annihilation. With the proliferation of commercial laser systems, offering both high repetition rates and high pulse energies, have come new opportunities for high sensitivity pump-probe measurements at low pump fluences. However, experimental considerations needed to fully leverage the statistical advantage of these laser systems have not been fully described. Here, we demonstrate a high repetition rate, broadband transient spectrometer capable of multichannel shot-to-shot detection at 90 kHz. Importantly, we find that several high-speed cameras exhibit a time-domain fixed pattern noise resulting from interleaved analog-to-digital converters, which is particularly detrimental to the conventional “ON/OFF” modulation scheme used in pump-probe spectroscopy. Using a modified modulation and data processing scheme, we achieve a noise level of 10−5 in 4 s for differential transmission, an order of magnitude lower than for commercial 1 kHz transient spectrometers for the same acquisition time. We leverage the high sensitivity of this system to measure the differential transmission of monolayer graphene at low pump fluence. We show that signals on the order of 10−6 OD can be measured, enabling a new data acquisition regime for low-dimensional materials.
Pressure effects on the resonant attenuation of soft porous beads-based materials for underwater acoustics
Authors: Lacour Thomas , Poupart Romain , Mondain-Monval Olivier , Aristégui Christophe , Poncelet Olivier , Brunet Thomas
Published: April 2023

Dedicated coating materials for anechoism and furtivity in underwater acoustics must exhibit a strong reliability regarding their mechanical resistance to hydrostatic pressure. Soft porous materials, especially, a distribution of soft porous beads within a polyurethane matrix, have been previously proposed as an acoustic insulator device. The purpose of the present letter is to investigate the attenuation efficiency of soft porous silicone beads-based materials while being exposed to uniaxial loads mimicking hydrostatic pressures encountered in underwater acoustics. The acoustic performance of this locally resonant material is then compared to the classical coating technology using micro-balloons. The use of an adapted surfactant (a silicone alkyl polyether compound) in the fabrication process of the soft porous silicone-based beads, obtained through an emulsion templating process, leads to particles exhibiting an open porosity. The (resonant) attenuation of the soft porous beads-based material remains greater than the micro-balloons-based material until several bars. Above this critical resilience value, the mechanical stress irreversibly damages the soft porous beads.
Trapping proteins on nanopores by dielectrophoresis
Authors: Colburn Taylor , Matyushov Dmitry V.
Published: April 2023

Interest in the phenomenon of dielectrophoresis has gained significant attention in recent years due to its potential for sorting, manipulation, and trapping of solutes, such as proteins, in aqueous solutions. For many decades, protein dielectrophoresis was considered impossible, as the predicted magnitude of the force arising from experimentally accessible field strengths could not out-compete thermal energy. This conclusion was drawn from the mainstay Clausius–Mossotti (CM) susceptibility applied to the dielectrophoretic force. However, dielectric interfacial polarization leading to the CM result does not account for a large protein dipole moment that is responsible for the dipolar mechanism of dielectrophoresis outcompeting the CM induction mechanism by three to four orders of magnitude in the case of proteins. Here, we propose an explicit geometry within which the dipolar susceptibility may be put to the test. The electric field and dielectrophoretic force are explicitly calculated, and the dependence of the trapping distance on the strength of the applied field is explored. A number of observable distinctions between the dipolar and induction mechanisms are identified.
Correlating structural distortions and optical shifts in carboxylate-exchanged CdSe nanoplatelets
Authors: Peifer Shoshanna , Wiscons Ren A. , Olshansky Jacob H.
Published: April 2023

Quasi-2D nanomaterials such as semiconducting nanoplatelets (NPLs) have drawn considerable interest due to their tunable optical properties and large surface to volume ratios. Cadmium selenide (CdSe) NPLs are of particular fundamental interest since their thicknesses can be controlled with atomic precision using well-established solution-phase synthetic techniques. Additionally, their large surface area makes them especially susceptible to changes in the identity of the capping ligands and, therefore, good model systems for understanding surface chemistry. In the current work, we explore the role of these ligands in altering the lattice parameters and optical properties of CdSe NPLs. We build on prior research that has employed varying binding groups, including thiols, phosphonic acids, and halides, to demonstrate ligand-dependent optical bandgap changes and concomitant lattice distortions as determined by powder x-ray diffraction (PXRD). Our work investigates the correlations between ligand-induced optical and structural changes with a series of ligands that maintain a consistent carboxylic acid binding group, thus allowing us to probe secondary ligand effects. We perform ligand exchanges on oleic acid-capped CdSe NPLs with benzoic acids, cinnamic acids, and cyclohexanecarboxylic acid. In all cases, the optical bandgap decreases upon ligand exchange, and a correlated expansion in the thickness of the NPLs is observed via PXRD. We also observe that the benzoic acids produce larger optical and structural distortions than the cinnamic acids. We show that the optical and structural correlation is nearly quantitatively described by quantum confinement effects, with the thicker quantum wells exhibiting smaller energy gaps.
Enantio-specific state transfer of chiral molecules through enantio-selective shortcut-to-adiabaticity paths
Authors: Cheng Jian-Jian , Ye Chong , Li Yong
Published: April 2023

An interesting method of fast enantio-specific state transfer (ESST) is proposed for cyclic three-level systems of chiral molecules. We show that the fast population transfer via shortcut to adiabaticity can be accomplished for the cyclic three-level system of a general (chiral) molecule with invariant-based inverse engineering of the coupling strengths. By choosing appropriate parameters, the two enantiomers, which are initially prepared in their ground states in the three-level systems, will evolve respectively along their enantio-selective shortcut-to-adiabaticity paths to different-energy final states simultaneously, thereby achieving the fast ESST.
Three-phase flow simulation of beach erosion induced by breaking solitary waves
Authors: Huang Shijie , Huang Zhenhua
Published: April 2023

A three-phase (air, water, and sediment) flow computational-fluid-dynamics model based on OpenFOAM was used in the present work to simulate the beach erosion induced by breaking solitary waves. The simulation results were first validated by comparing them against experimental measurements. The simulated time series of the surface elevation and pore pressure, as well as the simulated beach profile after erosion, compared fairly well with the experiment. The simulation results showed that the wave runup and rundown processes were accompanied by distinct hydrodynamics and sediment transport characteristics. The hydrodynamics in the runup stage is featured by a weaker flow before the wave breaking and a stronger one afterward, which then gradually weakens toward the runup limit. The hydrodynamics in the rundown stage is featured by a generally weaker flow compared to the runup stage. The flow is also stronger before the hydraulic jump and weaker afterward. A flow reversal and the exfiltration process are captured by the numerical model at the end of the rundown stage. The sediment transport in the runup stage is featured by an intense rate but a short duration, while the sediment transport in the rundown stage is much slower but has a longer duration. As a result, the total amounts of the transported sediment in the runup and rundown stages were comparable to each other. Finally, a discussion on the limitations of the numerical model and possible modifications to further improve the model in the future is presented.