Non-uniform Particle Research Articles

A refined model of lithium-ion battery considering agglomerated active material and non-uniform graphite particle

This study presents a refined lithium-ion battery model based on the Newman model, incorporating agglomerate structures in the positive electrode and non-uniform particle size distribution in the negative electrode. The agglomerates in the positive region consist of nano-scale primary particles, pore spaces, and binders, while the negative region features a random distribution of particle sizes. The model employs the volume averaging method and integrates a thermal model to provide a comprehensive simulation framework. The results of the numerical calculations and experimental measurements show that the model is in good agreement with the experimental data. The predicted discharge capacity of the proposed model is significantly higher than that of the traditional P2D model. This improvement is primarily due to the increased diffusion distance in agglomerates and the non-uniform particle sizes, which result in substantial changes in overpotential, electrolyte concentration, and solid-phase lithium-ion distribution. The model effectively captures the complex electrochemical behavior during discharge, underscoring the importance of considering structural heterogeneities in battery modeling.

Commercial silica materials functionalized with a versatile organocatalyst for the catalysis of acylation reactions in liquid media.

Silica materials represent a promising material for the application in heterogeneous organocatalysis due to their readily modifiable surface and chemical inertness. To achieve high catalyst loadings, usually, porous carriers with high surface areas are used, such as special silica monoliths or spherical particles for backed bed reactors. Yet, their synthesis is elaborate, and thus less complex and cheaper alternatives are of interest, especially considering scaling up. In this work, two commercial silica materials functionalized with the organocatalyst 4-(dimethylamino)pyridine (DMAP) were used in catalytic acylation reactions: a mesoporous silica gel (Siliabond®-DMAP) and non-porous silica nanoparticles (Ludox®). Both were successfully used in the acylation of phenylethanol, but the latter required significantly longer reaction times, presumably due to mass-transfer limitations as a consequence of substantial agglomeration that limits the accessible amount of catalyst. Furthermore, it was shown that the influence of the linker molecule is negligible, since both reaction yields and the activation energy remain largely similar. As main result the commercial material Siliabond-DMAP, despite the non-uniform particles, exhibited significant yield in a flow setup, thus demonstrating the potential as support material for application in heterogeneous organocatalysis.

Grain-size distribution in suspension through open channel turbulent flow using space-fractional ADE

The main aim of the present study is to develop a mathematical formulation that can describe the grain-size distribution (GSD) of non-uniform sediments in suspension over erodible sediment beds in a wide open channel under non-equilibrium conditions. The two important characteristics of sediment particles, such as non-local mixing and the hiding-hindering effect during settling, has been considered in the current study. The traditional advection–diffusion equation (ADE) is taken in the modified form as fractional ADE which is capable of capturing non-local movement of particles unlike the traditional diffusion theory where particles jump within a restricted distance along the vertical direction over a small time interval. The equation is further modified for any kth class of non-uniform sediment and the effect of non-local movement is included in the expression of depth averaged sediment diffusivity also. The settling velocity of a particle is taken in a form that contains the effect of hiding and hindering due to the presence of non-uniform particles in the flow. The space-fractional derivative is taken in the Caputo sense where the order α of the fractional derivative varies from 1<α≤2. The non-local effect is considered in the bottom and top boundary conditions also and the governing equation with boundary and initial condition have been solved by Chebyshev collocation method along with Euler’s backward method. The temporal variation of concentration profiles for different size particles is studied by varying α and it is observed that the magnitude of concentration decreases for each size as α increases. Non-local effect on bottom concentration for different size particle is also studied and it is seen that overshooting of bottom concentration gradually decreases as α increases for a particular size. Sensitivity analysis of α on GSD at different heights also has been done. The model has been validated for GSD under equilibrium conditions with available experimental data and it is found that the model aligns well when the non-local mixing effect is taken into account. At the end, an error analysis has been conducted to confirm the accuracy of the presented model.

Optical manipulation of magnetic microspheres Enables high-sensitivity Fiber-optic magnetic field sensors

This study uses single-fiber optical tweezers to capture non-uniform magnetic particles, producing a novel type of magnetic field sensor for implementing the measurement of external magnetic field changes. A tapered fiber optic probe is used to capture magnetic particles as a sensing probe, constituting an Fabry–Pérot (F-P) interferometric structure. When an external magnetic field is applied, the magnetic particles at the tip of the optical fiber are deflected, affecting the length change of the interference cavity. By reconstructing the axial displacement of the particles, the accurate measurement of the magnetic field within the range of 1–10 mT is successfully realized with a sensitivity of 258 nm/mT. The minimum detectable intensity is 1.44 nT/Hz. This method offers a feasible and effective solution for the realization of magnetic field measurements by using the capture of non-uniform magnetic particles, which can play an important role in the fields of medicine and biology.

Microfluidic-Generated Injectable Bulking Agents with Biocompatible Surfaces and Their Mid-term Outcomes in a Rat Model with Anal Sphincter Injury.

Bulking agents have gained attention as new, minimally invasive treatments for fecal incontinence. Various materials and surface treatment techniques have been extensively studied to ensure good biocompatibility and long-term stability. Despite significant improvements in biocompatibility, the nonuniform particle size of existing materials has led to other challenges, such as the induction of phagocytosis or reduction of injectability during in vivo tests. This study aimed to conduct a preclinical test of the midterm stability of bulking agents with newly formulated particles with uniform size. To this end, the particles were fabricated using microfluidics, resulting in a narrow size dispersity of less than 5% as the coefficient of variation, which is essentially distinct from conventional bulking agents. The microfluidic fabrication resulted in uniformly sized particles larger than the in vivo migratory limit of 80 μm and in a reduction in maximum injection pressure. Histological staining and microscopic observations confirmed proper positioning of the filler materials in vivo and a negligible immune response for up to 6 months, indicating successful midterm stability.

Investigations of inlet arrangement strategies and particle parameters on thermochemical performance in falling particle solar reactors

The reformation of methane to hydrogen and steam in a falling particle solar reactor (FPSR) is a promising method to use the solar energy, which converts solar energy into chemical energy. FPSR has higher operation temperature, higher pressure bearing capacity and more direct heat energy storage than those of traditional reactor. However, due to the short residence time of the particles, hydrogen production efficiency is reduced. Thus, inlet arrangement strategies and particle catalysts should be carefully designed to improve the thermochemical reaction performance of FPSR. In this contribution, the Eulerian-Eulerian model in CFD program (Fluent 2020 R2) is used to explore the effects of different particle inlet arrangement strategies, non-uniform particle mass flow inlet and particle size on the performance enhancement of methane steam reforming reaction. The results indicate that the two arrangement strategies show different trends in influencing hydrogen production efficiency. Besides, non-uniform particle mass flow rate also has a significant impact on hydrogen production efficiency, with the optimal arrangement conditions increasing the hydrogen production rate by 2.4831 mol/m−3(−|-) s−1. Additionally, smaller particle size demonstrates better hydrogen production efficiency, with a 0.15 mm particle size catalyst showing a 14.02 % improvement in hydrogen production efficiency compared to a 0.75 mm particle size. This contribution can provide a guidance for optimizing the heat and mass transfer performance of the falling particle solar reactor.

Highly sensitive and selective ratiometric fluorescence and colorimetric detection of Cr(VI) via in situ encapsulation of green/red carbon quantum dots in zeolite

To overcome the limitations arising from non-uniform particle size and solid-state aggregation of carbon quantum dots (CQDs), a novel dual-emissive ratiometric fluorescence probe, GCQDs@SBA-15/RCQDs@SBA-15 (G-RCQDs@SBA-15), has been successfully constructed by simplifying the synthesis process through in situ synthesis of CQDs in SBA-15 to further enhance their optical properties for highly sensitive detection of Cr(VI). The probe G-RCDs@SBA-15, based on green-emission carbon quantum dots (GCQDs) encapsulated in mesoporous molecular sieves SBA-15, provides the response signal, while red-emission carbon quantum dots (RCQDs) encapsulated in SBA-15 serve as an internal reference. The probe exhibits a satisfactory limit of detection (LOD) of 0.336 μM, which is 52 % lower than GCQDs/RCQDs. Importantly, the probe shows superior selectivity in detecting Cr(VI) compared to other metal ions. The fluorescence signal ratio of the probe decreases with increasing Cr(VI) concentration, resulting in a distinct change of fluorescence color from green to red. Based on UV–vis and fluorescence lifetime analysis, Inner filter effect (IFE) is considered the primary potential mechanism for the fluorescence color transition of G-RCDs@SBA-15 following the addition of Cr(VI). G-RCQDs@SBA-15 not only inherits the excellent optical properties of GCQDs and RCQDs but also shows high fluorescence and chemical stability. Considering the sensitive photoconversion properties of G-RCQDs@SBA-15, a smartphone-based laboratory device in combination with RGB analysis software has been used for Cr(VI) detection by directly capturing and analyzing fluorescence images. In addition, the sensing system is validated in the actual lake water samples, exhibiting recoveries from 83.3 % to 96.3 %, indicating its excellent practicality for Cr(VI) detection in real samples.

Scattering characteristics of dual counter-propagation high-order circularly symmetric Bessel beam by a multilayer chiral sphere.

The interaction between dual counter-propagating high-order circularly symmetric Bessel beams (CSBBs) and multi-layered chiral particles is investigated. Within the framework of generalized Lorenz-Mie theory (GLMT), the distribution characteristics of the superposition of two beams are studied based on the vector superposition theorem. The near-field, internal field, and far-field radar cross section (RCS) of the dual-layered chiral sphere illuminated by dual CSBBs are obtained according to the boundary conditions. By comparing the results of RCS with those from the references for two cases: first, when CSBBs degenerate into plane waves incident on multi-layered chiral sphere, and second, when Bessel beams illuminate isotropic multi-layer sphere degenerated by chiral multi-layered sphere, the effectiveness of the principle and program exhibited here is confirmed. The impact of various parameters on the distribution of the superposed field, the near-field, internal field, and far-field RCS of the particles are analyzed in detail, such as the order, half-cone angle, incidence angle, and polarization angle. The research results in this paper provide theoretical assistance for understanding the interaction between dual CSBBs and non-uniform chiral multi-layered particles and have important value in realizing optical manipulation of complex chiral layered particles.

Temperature evolution of laser-ignited micrometric iron particles: A comprehensive experimental data set and numerical assessment of laser heating impact

This study examines the effects of laser heating on the ignition and critical combustion characteristics, such as temperature and burn time, of individual iron particles. It provides time-dependent temperature profiles of laser-ignited particles across a broad spectrum of particle size distributions and oxygen concentrations obtained from experiments, which are a useful database for further development and validation of iron particle combustion models. The herein reported datasets significantly complement those existing in the literature. In the current study, the raw data are thoroughly re-evaluated using refined approaches. For the experimental canonical configuration of single iron particle combustion, an ignition system based on laser heating provides several advantages in overcoming temperature field uncertainties and facilitating controlled environments for optical diagnostics. Despite the inherent uncertainties in laser heating, associated with non-uniform intensity profiles and particle size variations, this study addresses the critical question of how these uncertainties affect in situ measurements of particle temperature and time to reach peak temperature. This study, conducted using a numerical model, reveals a dependence of the particle temperature after laser heating on particle size. However, this dependence does not significantly impact the key parameters of iron-particle combustion, such as the maximum temperature and burn time of the laser-ignited iron particle. The study also presents a comparison between the simulated particle temperature histories and those derived from two-color pyrometry measurements for a wide range of particle size distributions and oxygen concentrations. Notably, by implementing a laser-heating sub-model into an iron particle combustion model, assuming external-diffusion-limited oxidation only up to stoichiometric FeO, the temperature evolution up to the maximum temperature is reasonably captured for a wide range of particle sizes (20–53μm) and oxygen volumetric fractions (14–21vol% O2 mixed with N2). However, with increasing oxygen concentration, the external-diffusion limited model significantly overestimates the heating rate and subsequently the maximum particle temperature.

Experimental simulation evaluation and control measures of paving segregation for the stone matrix asphalt mixtures

The aggregate segregation for asphalt mixtures, characterized by non-uniform particle distribution, significantly undermines the quality and performance of pavements. This investigation aims to explore and reveal the mechanisms underlying segregation, including raw material properties and construction procedures. Novel evaluation methods, predictive metrics, and control measures were introduced using the developed apparatus. The results indicate that physical properties, particle morphology, and gradation are fundamental factors driving segregation. Spatial hindrance, interfacial friction, collision, and self-organization collectively coordinate particle spatial migration and distribution. Excessive coarse particles induce interstitial displacement, while that of fine particles trigger third-body lubrication. The lubricating-bonding factor η was proposed to characterize asphalt regulation. Segregation prediction based on composite angularity facilitates informed raw material selection. In addition, measures to improve paving quality and efficiency during loading, unloading, and auger mixing were proposed. This research contributes to the understanding of segregation mechanisms, enabling early prevention and effective management strategies.

Synthesis, characterization, and antifungal properties of chrome-doped hydroxyapatite thin films

The development of thin films of chromium-doped hydroxyapatite (20CrHAp) deposited on silicon substrate by the spin coating method was realized for the first time. A coherent investigation of the physicochemical properties of 20CrHAp thin films was also carried out for the first time. The obtained thin films were studied by various techniques such as, scanning electron microscopy (SEM), atomic force microscopy (AFM), Fourier transform infrared spectroscopy (FTIR) investigations and fractal analysis. By scanning electron microscopy (SEM) studies were obtained valuable information about the surface morphology of the 20CrHAp thin films. The zeta potential (ZP), Dynamic light scattering (DLS) and ultrasound measurements (US) were used in order to evaluate the stability of 20CrHAp suspension. The ratio between the hydrodynamic diameter obtained by DLS and the particle diameter obtained by SEM was 1.6. The SEM results on 20CrHAp thin films suggested that the sample possess a conglomerate of nanoparticles unevenly distributed on their surface. The surface morphology of the 20CrHAp thin films was studied with the aid of atomic force microscopy (AFM). The AFM topography of the 20CrHAp thin film's surface highlighted that the thin films present the morphology of a continuum deposited layer composed of non-uniform particle conglomerates. The presence of hydroxyapatite on the surface of silicium substrate was revealed by the results of Fourier transform infrared spectroscopy (FTIR) investigations. The antifungal evaluation of the 20CrHAp thin films was performed using Candida albicans 10,231 ATCC fungal strain. The antifungal assays results depicted that the 20CrHAp thin films inhibited the fungal biofilm formation. More than that, the results of the antifungal studies revealed that 20CrHAp thin films exhibited good inhibitory effects on the development of the fungal cells on their surface. Furthermore, our investigation delves into the realm of Minkowski Functionals and fractal/multifractal analysis as applied to the examined films. Our findings reveal that nanocomposite coatings containing 20CrHAp exhibit robust antifungal characteristics, suggesting their viability as a compelling solution for advancing antifungal devices in biomedical contexts.

Growth of Helical Coiled Double and Triple Walled Carbon Nanotubes at Low Temperature using FeMoMgO catalyst

Abstract Helical coiled double and triple walled carbon nanotubes (CNTS) were synthesized using chemical vapor deposition (CVD) method using FeMoMgO catalyst. The FeMoMgO catalyst was prepared using combustion process followed by multi walled CNTs synthesize. The final products were characterized by X-Ray diffraction (XRD), FT-IR, SEM, TEM and FESEM (surface morphology) along with electron dispersion X-ray spectrometer (EDX). The XRD results show that Fe is well incorporated with Mg which indicates crystalline in nature. FT-IR, results confirm the presence of functional group and metal ion. FESEM indicates the formation of larger and non-uniform particles with higher active sites. SEM and TEM results show that at low temperature coiled CNTs were formed with 2-5nm in diameter. In conclusion that Helical coiled double and triple walled CNTs were synthesized using FeMoMgO Catalyst at low temperature.

Effects of broken β-Mg17Al12 and non-uniform Mg2Pb particles introduced by EX-ECAP on microstructure and mechanical properties of Mg–Pb-9.2Al-0.8B alloys

Mg–Pb-9.2Al-0.8B alloy faces a significant strength-toughness balance problem in applications. To address this challenge, severe plastic deformation was applied to the alloy by combining traditional extrusion with multi-pass equal channel angular pressing (EX-ECAP). The research delves into the microstructural evolution (including broken β-Mg17Al12 and non-uniform Mg2Pb particles) and its effects on the strengthening mechanisms. The synergistic effects of grain boundary strengthening due to grain refinement, Orowan strengthening, geometrically necessary dislocation strengthening, and coefficient of thermal expansion strengthening collectively enhance the tensile strength and ductility, balancing the strength and toughness. The results showed an impressive ultimate tensile strength of 386.1 MPa, which is 2.33 times that of the as-cast alloy. The altered fracture morphology clearly indicated a transformation from brittle to brittle-ductile fracture mode. During the deformation process, the activation of dislocations, atomic-scale ripples, minor lattice distortions, and kink bands enhance the macroscopic flexibility. The introduction of EX-ECAP presents new opportunities for manufacturing high-performance Mg–Pb-9.2Al-0.8B alloy through integrated deformation techniques.

Non-uniform magnetic particle capture based on single-fiber optical tweezers

In this study, single-fiber optical tweezers are used to capture polystyrene magnetic particles with non-uniform surfaces. By preparing the tip of the optical fiber probe in the shape of a protruding cone, the laser beam is highly converged at the tip of the fiber to form a strong focused light field, and the laser beam can pass through the gap between the inorganic magnetic particles on the surface of the magnetic particles and enter into the internal polystyrene to generate a gradient force and realize the stable capture of the magnetic particles. This method provides a feasible and effective solution for the capture of non-uniform polystyrene magnetic particles using optical fiber and opens up new possibilities for research in related fields.

Learning solid dynamics with graph neural network

Deep learning has shown great promise in solid physic dynamic simulation. By incorporating physical laws, recent works have further improved performance. However, existing methods rarely conform to macrophysics and incur computational costs. Furthermore, the velocity direction features of the current model have not been decomposed, forcing the model to learn vector operations. To address the aforementioned problems, we propose a Solid-Graph Network (Solid-GN), designed for more accurate and efficient learning of solid dynamics. Firstly, we design a novel and cost-effective symmetric direction encoding system that achieves macroscopic equivariance in 2D space by representing same relative directional relationships among particle pairs and their flipping version. Secondly, we propose a message-passing mechanism incorporated with the contact process, facilitating an accurate description of interactions through the decomposition of normal and tangential effects. Lastly, four novel datasets for solid dynamics with non-uniform radius particles are released, thereby enabling more complex and realistic physical simulations. Experimental evaluations conducted on five datasets demonstrate our model's performance concerning predictive accuracy, macroscopic equivariance, and computational cost over the state-of-the-art ones.

Improved Bi(III) absorption and selectivity in cubic TiP2O7 with three-dimensional ion channels

TiP2O7 with enhanced adsorption capacity and selectivity removal ability has emerged as a promising adsorbent for the treatment of heavy metal ions. Herein, layered and cubic TiP2O7@C (LTO and CTO) were prepared by a solvothermal method combined with calcination at 700 and 800 °C, respectively. Compared to the large and non-uniform particles of LTO, the prepared CTO exhibits a honeycomb-like interconnected porous structure composed of uniformly sized ∼25 nm particles and provides a higher concentration of P–OH and Ti–O bonds. Benefiting from the advantages of the physicochemical structure, the adsorption capacity of CTO for Bi(III) was about 1.9 times higher than that of LTO, with a value as high as 54.5 mg g−1. Furthermore, the removal efficiency of Bi(III) from a mixed solution containing eleven ions at a concentration of 10 mg L−1 was as high as 97.5 %, demonstrating its exceptional selective adsorption capacity for Bi(III). The Bi(III) adsorption process is controlled by surface hydroxyl functional groups and follows a quasi-secondary kinetic model. This work may shed light on the synthesis of TiP2O7 and its application in water purification.

Scattering properties of dual Bessel beams on chiral layered particle

The paper investigates the scattering analytical solution of arbitrary direction double zero-order Bessel beams (ZOBBs) incident on a non-uniform layered chiral sphere. Using the generalized Lorenz-Mie theory (GLMT), the electromagnetic field expansion expression of the double ZOBBs is obtained through the vector superposition of the spherical vector wave functions (SVWFs). Analytical solutions of the scattering on chiral layered particles by dual Bessel beams are derived based on the boundary condition. The iterative coefficient equations are constructed to obtain the expansion coefficients of the SVWFs in each region of the multi-layer chiral sphere. The variation of radar cross section (RCS) with angular distribution is numerically simulated, and the scattering results of layered chiral spheres degenerated into isotropic layered spheres are compared with the literature, which verifies the correctness of the theory and program. The effects of incident angle, polarization angle, cone angle and chiral parameters on the scattering characteristics of far region and internal field of the layered chiral particle are analyzed in detail. The theory and results can offer significant assistance in studying the optical properties of non-uniform chiral particles and complex biological cells irradiated by multiple beams and may also provide important practical value in the micromanipulation of multi-layered biological structures.

Adaptive fast nonlinear blind deconvolution based on nonuniform particle swarm optimization for the rolling bearing fault diagnosis

Although superior fault extraction performance is possessed by fast nonlinear blind deconvolution (FNBD) through the introduction of penalty terms and nonlinear features, its wide application is limited by the complexity and diversity of parameter selection. The fault extraction performance of FNBD is impacted by the contingency of parameter selection. To reduce the prior experience dependence of FNBD and improve the performance of fault extraction, an end-to-end adaptive fast nonlinear blind deconvolution (AFNBD) is proposed. First, the proposed nonuniform particle swarm optimization (NPSO) is employed to assign parameters to be optimized for each particle to construct its Hankel matrix, nonlinear features and objective functions. Secondly, Gaussian fitting is applied to modify the filters. Then, NPSO is utilized to update relevant parameters and the corresponding filter of each particle to explore the optimum filter. Finally, simulations and experiments verify the effectiveness of AFNBD and the results indicate that AFNBD is a powerful tool for incipient fault feature extraction.

Si,N co-doped carbon quantum dots in mesoporous molecular sieves: A fluorescence sensing platform for Cr(VI) detection

Carbon quantum dots (CQDs) are highly efficient fluorescent probes for metal ion detection; however, they are limited by non-uniform particle size, aggregation, and the inability to facilitate quantitative analysis. Herein, a smart host–guest strategy is utilized, wherein CQDs are immobilized in mesoporous molecular sieves, proving to be an effective method to minimize these drawbacks. Si,N-CQDs@SBA-15 is successfully synthesized by the one-step hydrothermal route using Si,N-CQDs precursor materials as guests and the mesoporous molecular sieve SBA-15 as the host. A good linear relationship between the concentration of Cr(VI) ions and fluorescent intensity is observed from 0 μM to 100 μM (R2 = 0.9986). Thelimitofdetection(LOD) is 0.213 μM, approximately three times lower than that of pristine Si,N-CQDs (0.677 μM). Additionally, Si,N-CQDs@SBA-15 exhibit good detection selectivity for Cr(VI) detection over other metal ions. Moreover, a smartphone-based laboratory device and RGB analysis app are employed to capture and analyze fluorescence images, revealing a LOD for Cr(VI) of 0.201 μM. Förster Resonance Energy Transfer (FRET) is identified as the possible mechanism for the fluorescence quenching of Si,N-CQDs@SBA-15 by Cr(VI) through UV–vis and fluorescence experiments. The practicability of the synthesized fluorescent probes is further validated in river water, yielding satisfactory spiked recoveries ranging from 99.24 % to 106.21 %.

The effect of divertor particle sources on scrape-off-layer turbulence

Tokamak edge turbulence is crucial for the cross-field transport of particles and energy away from the separatrix. A better understanding of what affects the turbulence helps to control the heat flux to the divertor targets and the wall. One potentially important factor is the ion particle source in the divertor, as the neutral pathways and the ionisation source distributions are different depending on the divertor geometry, e.g. vertical- and horizontal-target configurations. Numerically, how to represent the sources and mimic the effects on the SOL in the simulations is still an open question. In this paper, we use a 3D turbulence code STORM, based on drift-reduced Braginskii equations, to study the effects of the divertor particle source distribution on turbulence in a simplified 3D slab geometry. The results show that it requires a large amount of divertor particle source to be peaked near the separatrix to alter the heat flux deposited on the target in attached conditions. This large non-uniform particle source can locally enhance the turbulence in the divertor volume, which redistributes the energy flux to the target and reduces the maximum amplitude. Meanwhile, the plasma profiles evaluated at the outboard midplane, such as the amplitudes and fluctuations of the density and temperature, are marginally changed. Another consequence of our results is that the prediction of the temperature difference between the outboard midplane and the target would be underestimated, if the calculation only considers the conductive heat flux and ignores this enhanced cross-field transport in the divertor.