Particle Interactions Research Articles

Numerical Simulation of the Melting of Solid Particles in Thermal Convection with a Modified Immersed Boundary Method

A new immersed boundary method is proposed for the numerical simulation of the melting of solid particles in its own liquid at a high temperature. The main feature of the new method is the use of the modified direct-forcing immersed boundary method for the solution of the flow field and the sharp-interface immersed boundary method for the temperature field. The accuracy of the proposed method is validated via three problems: the sedimentation of a non-melting particle, the melting of a fixed particle under mixed thermal convection, and the sedimentation of a melting particle. The method is then applied to the investigation of the effects of various parameters, the particle interactions and the particle shape on the particle melting time. A correlation for the melting time of a circular particle in forced thermal convection is established as a function of the Reynolds, Prandtl, and Stefan numbers. The melting time of a particle in mixed thermal convection first increases and then decreases, as the Grashof number increases. The effects of the particle interactions on the melting time are complicated due to the natural convection between two particles. The sufficiently strong natural convection can even render the downstream particle melt faster than the single particle. For the same particle area, the elliptic particle with the aspect ratio being around 1.4 melts most slowly.

Quantum potential energy: Adaptive facades in architecture

This paper addressed the topic of creating quantum architecture through human awareness to transform the formal and spatial elements of architecture according to its environmental sustainability compatible with nature. The research emphasizes the creation of a built environment that uses natural resources to enhance the psychological and physical comfort of humans, relying on the quantum energy inherent in the interaction of particles, which is called “kinetic energy” in quantum mechanics, and it can be considered energy due to motion. The research aims to determine the recommended standards for use in designing the building facade according to the magnetic field lines. It focuses on the classification of smart interfaces in particular. The complexity of evaluating adaptive or dynamic facades is related to evaluating the performance of the facade elements and systems, the overall performance of the building, as well as the behavior and satisfaction of the occupants. The research seeks to present a conceptual and cognitive framework by linking the concept of potential kinetic energy and quantum theory with architecture and then presents a group of literary studies that will enrich and build the theoretical framework and then apply it to the groups of projects selected for practical study and then reach the final conclusions.

Interaction of complex particles: A framework for the rapid and accurate approximation of pair potentials using neural networks

Motivated by the limitations of conventional coarse-grained molecular dynamics for simulation of large systems of nanoparticles and the challenges in efficiently representing general pair potentials for rigid bodies, we present a method for approximating general rigid body pair potentials based on a specialized type of deep neural network that maintains essential properties, such as conservation of energy and invariance to the chosen origins of the particles. The network uses a specialized geometric abstraction layer to convert the relative coordinates of the rigid bodies to input more suitable to a conventional artificial neural network, which is trained together with the specialized layer. This results in geometric representations of the particles optimized for the specific potential. The network can be trained directly on scalar values to fit a model without explicit gradient and then used to efficiently evaluate the force and torque on the particles resulting from the potential. The concept is demonstrated with an atomistic interaction model for carbon nanotubes and the resulting model is compared with a common type of coarse-grained model optimized for the same potential, with even very small networks comparing favourably and larger networks achieving up to two orders of magnitude lower cost. The sensitivity to noise in the training data is investigated and the model is found to strongly reject noise up to 12.5% given a dataset of 107 samples. The performance of a proof-of-concept implementation is demonstrated on a variety of hardware, showing the models viability for large-scale simulations. Furthermore, generalization to soft bodies and potentials for polydisperse systems are discussed. Published by the American Physical Society 2024

Highly chiral exceptional point in coupled resonators perturbed by nanoscatterers

With employing strong chirality in an optical system, the direction of light propagation can be controlled and subwavelength particles can be detected. Here, we show that a different kind of chiral exceptional point (EP) with high (spatial) chirality can appear in a coupled resonator perturbed by nanoscatterers, in which both the distance and position of the scatterers can be tuned. We achieve strong chiral EP in two different distances between the resonators, with chirality around 0.99, in both cases. Besides, chiral EP associated with the higher harmonic whispering gallery mode is achieved, with chirality around 0.95. We also investigate the interaction of particles with same and different spin of light, which can mimic the spin-up and spin-down of electrons in quantum mechanics. The proposed device provides a tunable scheme to achieve high directionality of different cavity modes by incorporating one or more nanoscatterers. With incorporating more than one tunable mechanism such as nanoscatterers, nonlinearity, and time-modulation, simultaneously, the conventional limitations in chirality and sensitivity may be surpassed in the presence of unwanted imperfections of fabrication and noisy environment.

Global stability for McKean–Vlasov equations on large networks

Abstract We investigate the mean-field dynamics of stochastic McKean differential equations with heterogeneous particle interactions described by large network structures. To express a wide range of graphs, from dense to sparse structures, we incorporate the recently developed graph limit theory of graphops into the limiting McKean–Vlasov equations. Global stability of the splay steady state is proven via a generalised entropy method, leading to explicit graph structure-dependent decay rates. We highlight the robustness of the entropy approach by extending the results to the closely related Sakaguchi–Kuramoto model with intrinsic frequency distributions. We also present central examples of random graphs, such as power law graphs and the spherical graphop, and analyse the limitations of the applied methodology.

Detection of bifurcation in phase-space perturbative structures across transient wave–particle interaction in laboratory plasmas

A key ingredient for realizing a magnetically confined tritium-deuterium plasma fusion reactor is plasma heating by fusion-born high-energy helium ions, as a chained cycle of "nuclear burning." Efficient collisionless plasma heating by high-energy particles is anticipated when their energy is directly transferred to the plasma through waves. Those processes often involve nonlinear structure formations in phase-space, spanned by real-space and velocity-space coordinates, that significantly influence heating efficiency. To date, experimental knowledge of phase-space structure formation physics is severely limited, due to lack of experimental diagnostic schemes. Here, state-of-the-art hardware and software approaches for phase-space perturbative structure detection are introduced. A bifurcation in the phase-space structure formation is found, which affects the plasma heating efficiency. A confinement magnetic field structure is shown to be a potential knob for nuclear-burning control through phase-space manipulation.

A fully coupled solid-particle microphysics scheme for stratospheric aerosol injections within the aerosol–chemistry–climate model SOCOL-AERv2

Abstract. Recent studies have suggested that injection of solid particles such as alumina and calcite particles for stratospheric aerosol injection (SAI) instead of sulfur-based injections could reduce some of the adverse side effects of SAI such as ozone depletion and stratospheric heating. Here, we present a version of the global aerosol–chemistry–climate model SOCOL-AERv2 and the Earth system model (ESM) SOCOLv4 which incorporate a solid-particle microphysics scheme for assessment of SAI of solid particles. Microphysical interactions of the solid particle with the stratospheric sulfur cycle were interactively coupled to the heterogeneous chemistry scheme and the radiative transfer code (RTC) for the first time within an ESM. Therefore, the model allows simulation of heterogeneous chemistry at the particle surface as well as feedbacks between microphysics, chemistry, radiation and climate. We show that sulfur-based SAI results in a doubling of the stratospheric aerosol burden compared to the same mass injection rate of calcite and alumina particles with a radius of 240 nm. Most of the sulfuric acid aerosol mass resulting from SO2 injection does not need to be lifted to the stratosphere but is formed after in situ oxidation and subsequent water uptake in the stratosphere. Therefore, to achieve the same radiative forcing, larger injection rates are needed for calcite and alumina particle injection than for sulfur-based SAI. The stratospheric sulfur cycle would be significantly perturbed, with a reduction in stratospheric sulfuric acid burden by 53 %, when injecting 5 Mt yr−1 (megatons per year) of alumina or calcite particles of 240 nm radius. We show that alumina particles will acquire a sulfuric acid coating equivalent to about 10 nm thickness if the sulfuric acid is equally distributed over the whole available particle surface area in the lower stratosphere. However, due to the steep contact angle of sulfuric acid on alumina particles, the sulfuric acid coating would likely not cover the entire alumina surface, which would result in available surface for heterogeneous reactions other than the ones on sulfuric acid. When applying realistic uptake coefficients of 1.0, 10−5 and 10−4 for H2SO4, HCl and HNO3, respectively, the same scenario with injections of calcite particles results in 94 % of the particle mass remaining in the form of CaCO3. This likely keeps the optical properties of the calcite particles intact but could significantly alter the heterogeneous reactions occurring on the particle surfaces. The major process uncertainties of solid-particle SAI are (1) the solid-particle microphysics in the injection plume and degree of agglomeration of solid particles on the sub-ESM grid scale, (2) the scattering properties of the resulting agglomerates, (3) heterogeneous chemistry on the particle surface, and (4) aerosol–cloud interactions. These uncertainties can only be addressed with extensive, coordinated experimental and modelling research efforts. The model presented in this work offers a useful tool for sensitivity studies and incorporating new experimental results on SAI of solid particles.

Fibrous‐biocomposites scaffold of natural rubber with bioactive glass–ceramic particles obtained by solution blowing spinning

AbstractBioactive glass‐ceramics (BGs) are widely used in clinical applications due to their excellent biodynamic and biological properties, though their low mechanical strength limits their use in load‐bearing contexts. This study aimed to develop fibrous biocomposite scaffolds based on natural rubber (NR) reinforced with BG particles, such as biosilicato (BioS) and 45S5‐K (BL0), to improve tensile strength, biocompatibility, and bioactivity for biomedical applications, such as tissue engineering. Morphological, tensile, thermal, and biological tests were conducted to evaluate the impact of BG particles on the NR fibrous matrix. TG/DTG analysis revealed similar decomposition profiles for NR/BioS and NR/BL0 biocomposites compared to NR mats, with primary degradation occurring in the 290–450°C range. Tensile tests demonstrated that the addition of 30 mass% BioS or BL0 enhanced the ultimate tensile strength (σbreak) of the NR matrix from 1.44 ± 0.08 to 3.38 ± 1.31 MPa (NR/BioS) and 1.97 ± 0.53 MPa (NR/BL0). The Cole–Cole plot indicated system heterogeneity and strong NR‐BG particle interactions. Cytotoxicity tests revealed over 70% MSC viability for NR, NR/BioS, and NR/BL0 biocomposites, meeting ISO 10993‐5:2009 standards. These findings suggest that incorporating BioS and BL0 enhances the mechanical and biological properties of NR‐based scaffolds, making them suitable for biomedical applications, such as bone regeneration.

Exploring Kink Solitons in the Context of Klein–Gordon Equations via the Extended Direct Algebraic Method

This work employs the Extended Direct Algebraic Method (EDAM) to solve quadratic and cubic nonlinear Klein–Gordon Equations (KGEs), which are standard models in particle and quantum physics that describe the dynamics of scaler particles with spin zero in the framework of Einstein’s theory of relativity. By applying variables-based wave transformations, the targeted KGEs are converted into Nonlinear Ordinary Differential Equations (NODEs). The resultant NODEs are subsequently reduced to a set of nonlinear algebraic equations through the assumption of series-based solutions for them. New families of soliton solutions are obtained in the form of hyperbolic, trigonometric, exponential and rational functions when these systems are solved using Maple. A few soliton solutions are considered for certain values of the given parameters with the help of contour and 3D plots, which indicate that the solitons exist in the form of dark kink, hump kink, lump-like kink, bright kink and cuspon kink solitons. These soliton solutions are relevant to actual physics, for instance, in the context of particle physics and theories of quantum fields. These solutions are useful also for the enhancement of our understanding of the basic particle interactions and wave dynamics at all levels of physics, including but not limited to cosmology, compact matter physics and nonlinear optics.

Physics Models and Machine Learning in Molecular Dynamics

Abstract. Tackling the complexity of particle interactions, this investigation introduces a unified computational methodology employing Moldy, Gnuplot, and Visual Molecular Dynamics (VMD). Inspired by the n-body problem's persistent intrigue, specifically the three-body dynamics within molecular systems, we leverage Molecular Dynamics (MD) simulations to forecast and scrutinize the nuanced behavior of atomic and molecular entities. Moldy, a flexible MD software, facilitated the simulation of particle trajectories and interactions across diverse scenarios, with meticulous documentation of the resulting data. For visual analytics and insight extraction, Gnuplot crafted detailed plots depicting kinetic and potential energies alongside other thermodynamic metrics over temporal scales. The integration of VMD culminated in our analysis by vividly portraying the molecular motions, enhancing comprehension of emergent patterns. This study not only endorses Moldy's precision in MD simulations but also highlights the potent alliance among simulation, analysis, and visualization in elucidating intricate particle interactions. In summary, our work underscores the efficacy of the Moldy-Gnuplot-VMD triad as a formidable resource for scientists engaged in molecular motion prediction and analysis, paving fresh paths in computational physics and chemistry research.

Investigation on the interfacial and emulsion stabilized behavior of dextran/ferritin/resveratrol composite nanoparticles

Glycation of ferritin provides a viable approach to enhance its physicochemical and functional properties. However, there is limited research on the interfacial adsorption properties of glycated ferritin-based colloidal particles. Therefore, this study selected recombinant human H-chain ferritin (rHuHF), rHuHF encapsulated with resveratrol (rHuHF–Res), and rHuHF–dextran glycoconjugates loaded with resveratrol (Dex–rHuHF–Res) as emulsifiers to investigate their interfacial adsorption properties. The results revealed that Dex–rHuHF–Res exhibited superior emulsifying properties and rheological behavior. It also increased the hydrophobicity of the microenvironment around Tyr and Trp residues, while hydrogen bonds, hydrophobic force, and salt bridge were identified as the most important intermolecular interactions. Dex–rHuHF–Res exhibited the biggest contact angle and lowest interface tension, which further reduced the diffusion (Kdiff) from the aqueous phase to the interface but promoted the penetration (Kp) and rearrangement (Kr) rates at the interface. Meanwhile, the emulsion stabilized by Dex–rHuHF–Res displayed excellent freeze-thaw stability, and Dex–rHuHF–Res can be more densely accumulated at the O/W interface to form an interface layer. These findings highlight the promising application of glycated ferritin in stabilizing Pickering emulsions, and deepen our understanding of the interplay among particle interaction, interface adsorption properties, and emulsion stability.

Numerical simulations on non-reactive multiphase flow during the transition from vent activation to venting with vent cap fragments in 18650 lithium-ion batteries

Mandatory safety devices, prevalent in lithium-ion batteries (LIBs), enable current interrupt device (CID)-and vent-activated power-off protection by sensing the electrochemical gas production boost triggered by thermal runaway (TR). For an in-depth understanding of the early warning of safety devices, the thermodynamic and multiphase flow behaviour of gases-vent particles interaction under the non-combustion venting phase is numerically investigated. From the gas phase simulation results, the flow field structure of the counter-rotating vortex pairs (CVPs) bounded by vent cap fragments enhances the heat transfer between ambient air and the venting gas, and the local venting gas temperature can reach a drop of >100 K. The transient three-dimensional spatial evolution characteristics of vent particles interacting with vent cap fragments at the early stage of the venting process after 18650 thermal runaway-induced vent-activation is originally demonstrated, including gas temperature and velocity as well as particle size and temperature. The spatial distributions of polydisperse particle size and temperature under the process of non-combustion venting are used to characterize the ejected particles' behaviour, which reveals the particle trajectories in particle-laden streams and their heat-transfer characteristics. The results show that ejected particles with relatively high temperatures and large sizes are mainly clustered within the cell diameters, and possible thermal runaway propagation inside the module can be triggered by the smaller-size particles of higher temperature sprayed in the periphery when the blocking effect of the vent cap fragment is weakened.

Evaluation of the cross sections and photoelectron angular distribution parameters following atomic photoionization under extreme conditions

In this manuscript, we report on a theoretical study of the atomic structures, cross sections, and photoelectron angular distribution parameters following the atomic photoionization under extreme conditions. To achieve this goal, a relativistic approach using the Dirac-Coulomb Hamiltonian within the framework of relativistic configuration interaction, taking advantage of independent particle basis wave functions, is proposed. To describe the interaction of charged particles in the ideal and non-ideal plasmas, the Debye potential and the pseudopotential are implemented, the latter being derived from a progressive resolution of the Bogolyubov chain equations. Both bound and continuous state wave functions, essential for a comprehensive understanding of quantum systems, are determined from the modified local central potential, which is obtained in a self-consistent manner to represent the electronic shielding effect on the nuclear potential. The photoionization processes are evaluated using the relativistic distorted wave approach, which is consistent with the principles of relativistic Dirac theory and thus provides an accurate description of the dynamics. As a test desk, the present method is applied to the evaluation of the energies, ionization potentials, wave functions, cross sections, and photoelectron angular distribution parameters, using the single photon ionization of the Li-like Fe XXIV ions as the basis for analysis. Our results demonstrate that the plasma environment effect not only decreases the ionization potentials and increases the cross sections but also affects the photoelectron angular distribution parameters across different shells, leading to a more balanced and symmetrical photoelectron distribution pattern. A detailed comparison is made between our results, and the available well-established theoretical predictions and experimental data of the unshielded case in the literature shows a good agreement. The present work provides novel insights and theoretical models that not only help us to better understand the fundamental properties of the complex systems but are also beneficial for innovative applications in the study of astrophysical and laboratory plasmas.

Astroparticles from X-Ray Binary Coronae

The recent observation of high-energy neutrinos from the Galactic plane implies an abundant population of hadronic cosmic-ray sources in the Milky Way. We explore the role of the coronae of accreting stellar-mass black holes as such astroparticle emitters. We show that the particle acceleration and interaction timescales in the coronal region are tied to the compactness of the X-ray source. Thus, neutrino emission processes may similarly happen in the cores of active galactic nuclei and black hole X-ray binaries (XRBs), despite their drastically different masses and physical sizes. We apply the model to the well-measured XRB Cygnus X-1 and find that the cascaded gamma rays accompanying the neutrino emission naturally explain the GeV emission that only presents during the source’s hard state, while the state-averaged gamma-ray emission explains the LHAASO observation above 20 TeV. We show that XRB coronae could contribute significantly to the Galactic cosmic-ray and Galactic plane neutrino fluxes. Our model predicts variable high-energy neutrino emission from bright Galactic XRBs that may be observed by IceCube and future neutrino observatories.

Size-polydispersity-induced effects on the structure of active Brownian pseudo-hard disks

Studies of the effects of particle-size polydispersity or of particle interactions on active matter have been limited to determine and analyze the system short-time dynamics in the high-density regime. On the other hand, the effects of polydispersity on the structural behavior of active systems are of relevance and have received much less attention. In this paper, we comprehensively analyze the effects of size dispersion of pseudo hard-disk active Brownian particles, on its structural behavior at different system densities and different self-propelling velocities, thus elucidating the interplay of these features with the polydispersity. This is introduced into our analysis by well-known particle size distributions in such a manner that the average size is fixed, but with a variance that accounts for different dispersion of the particle size according to: Gaussian, Weibull, uniform and “two point” distribution. Local and global structural properties of the system are determined under these considerations. We observe that activity and size polydisperse effects become relevantly conspicuous at densities above the motility induced phase separation critical point of the monodispersal fluid. We notice that, while the activity promotes a more defined local and global structural arrangement, the polydispersity decreases such structure, observing the greatest effect when the particle size is defined by a uniform distribution.

Measurement of inter-particle Hamaker constants in mineral materials using atomic force microscopy

The Hamaker constant is essential for quantifying particles interactions; however, its study has been limited due to technical constraints. While atomic force microscopy (AFM) can measure probe-to-particle surface interaction forces, it cannot directly measure particle-to-particle interaction forces. To address this issue, this paper introduces an AFM-based test method to quantify the interaction force between particles and a new approach for calculating the Hamaker constant. Using these methods, the particle-to-particle Hamaker constants of cement and fly ash in various environments were investigated. Results showed that adhesion values followed a log-normal distribution and that both adhesion and Hamaker constants varied significantly between materials. The measured Hamaker constants of different mineral materials ranged from 22.79 to 38.26 × 10−20 J in air and from 4.79 to 14.47 × 10−20 J in water, with material properties and testing environment identified as primary influencing factors.

Research on the Correlation between Quantum Entanglement and Thinking Consciousness

The development of quantum technology has profoundly influenced research on consciousness. By analyzing the interaction of various microscopic particles in the universe, the article proposed that all things exhibit interconnected non-locality in both time and space, and that the interrelated connections of everything in the universe are based on quantum entanglement. Through analysis of the cellular and nervous system functions of organisms, as well as the influence of quantum science theories on consciousness and combined with research results in related fields, this paper presents the following viewpoints: first, life bodies exhibit quantum entanglement phenomena. Second, biological electricity phenomena are closely tied to consciousness. Third, both life bodies and non-life bodies are conscious, but different entities exhibit varying degrees of strong and weak consciousness. The strong and weak thinking consciousness influences the fluctuation of quantum and the size of quantum entanglement degree. Quantum fluctuations affect the consciousness of both life bodies and non-life bodies, and the entanglement quantum influences the degree of inductance between each other. Finally, the combination of quantum entanglement technology and thinking consciousness can realize the interconnection between human beings and the universe. Consciousness may affect the results measured in quantum mechanics when people observe. However, the macroscopic world mainly adopts the laws of classical physics to solve problems in life. Under certain conditions, the law of quantum physics and the law of classical physics can affect people’s lives together. No matter what angle we view the material world, it is real, and the universe is not illusory.

Limits on scalar dark matter interactions with particles other than the photon via loop corrections to the scalar-photon coupling

There is limited information about the interaction strength of a scalar dark matter candidate with hadrons and leptons for a scalar particle mass exceeding 10−3 eV while its interaction with photon is well studied. The scalar-photon coupling constant receives quantum corrections from one-loop Feynman diagrams which involve the scalar-lepton, scalar-quark, and scalar-W-boson vertices. We calculate these one-loop quantum corrections and find new limits on the scalar particle interactions with electron, muon, tau, quarks, nucleons, gluons, Higgs, and W-bosons by repurposing the results of experiments measuring the scalar-photon interaction. Limits on interactions of heavy leptons and quarks have been obtained for the first time, and limits on other interactions in certain mass intervals are 2 to 15 orders of magnitude stronger than those presented in previous publications and exclude the resolution of the muon g−2 anomaly with scalar particle. Published by the American Physical Society 2024

Pseudo-Quantum Electrodynamics: 30 Years of Reduced QED

Charged quasiparticles, which are constrained to move on a plane, interact by means of electromagnetic (EM) fields which are not subject to this constraint, living, thus, in three-dimensional space. We have, consequently, a hybrid situation where the particles of a given system and the EM fields (through which they interact) live in different dimensions. Pseudo-Quantum Electrodynamics (PQED) is a U(1) gauge field theory that, despite being strictly formulated in two-dimensional space, precisely describes the real EM interaction of charged particles confined to a plane. PQED is completely different from QED(2 + 1), namely, Quantum Electrodynamics of a planar gauge field. It produces, for instance, the correct 1/r Coulomb potential between static charges, whereas QED(2 + 1) produces lnr potential. In spite of possessing a nonlocal Lagrangian, it has been shown that PQED preserves both causality and unitarity, as well as the Huygens principle. PQED has been applied successfully to describe the EM interaction of numerous systems containing charged particles constrained to move on a plane. Among these are p-electrons in graphene, silicene, and transition-metal dichalcogenides; systems exhibiting the Valley Quantum Hall Effect; systems inside cavities; and bosonization in (2 + 1)D. Here, we present a review article on PQED (also known as Reduced Quantum Electrodynamics).

Spaceborne COTS-Capsule hodoscope: Detecting and characterizing particle radiation

The COTS-Capsule Spaceborne hodoscope was launched into low Earth orbit aboard the International Space Station and operated from 2021 to 2022. The primary objectives of the payload are measuring and characterizing the radiation environment within the space station, serving as a technology demonstrator for the COTS-Capsule radiation mitigation apparatus, and testing the interaction of high-energy cosmic particles on-orbit with our detectors. The payload features a particle hodoscope equipped with an array of novel detectors based on polyvinyl toluene scintillators and silicon photomultiplier sensors that are used for radiation detection and characterization employing 2D intensity-based triangulation. This paper provides a comprehensive account of the COTS-Capsule payload’s construction, preflight performance, testing, qualification, and on-orbit calibration. The hodoscope, sensitive to ionizing cosmic particles, facilitates impinging particle track reconstruction by multi-detector 2D position estimation, energy deposition estimation, and linear energy transfer estimation.