Distribution Of Spherical Particles Research Articles

Accurate models of the added mass force of a uniform random distribution of spherical particles or bubbles

Accurate models of the added mass force of a uniform random distribution of spherical particles or bubbles

Antifungal Activity of Newly Formed Polymethylmethacrylate (PMMA) Modification by Zinc Oxide and Zinc Oxide-Silver Hybrid Nanoparticles.

Incorporating nanoparticles into denture materials shows promise for the prevention of denture-associated fungal infections. This study investigates the antifungal properties of acrylic modified with microwave-sintered ZnO-Ag nanoparticles. ZnO-Ag nanoparticles (1% and 2.5% wt.) were synthesized via microwave solvothermal synthesis (MSS). Nanoparticles were characterized for phase purity, specific surface area (SSA), density, morphology, and elemental composition. ZnO and ZnO-Ag nanoparticles were added to acrylic material (PMMA) at concentrations of 1% and 2.5% and polymerized. Pure PMMA (control) and obtained PMMA-nanocomposites were cut into homogeneous 10 × 10 mm samples. Antifungal activity of nanoparticles and PMMA-nanocomposites against C. albicans was tested using minimal inhibitory concentration (MIC) determination, and biofilm formation was assessed using crystal violet staining followed by absorbance measurements. Laboratory tests confirmed phase purity and uniform, spherical particle distribution. MIC results show antifungal activity of 1% Ag nanoparticles and the PMMA-2.5% (ZnO-1% Ag) nanocomposite. PMMA-1% (ZnO-1% Ag) nanocomposite and 1% ZnO-Ag nanoparticles are efficient in preventing biofilm formation. However, ZnO nanoparticles showed antibiofilm activity, and the PMMA-ZnO nanocomposite does not protect against biofilm deposition. Incorporating hybrid ZnO-Ag nanoparticles into PMMA is a promising antibiofilm method, especially with ZnO-1% Ag nanoparticles.

Восстановление пространственной функции распределения неоднородностей покрытия по функции распределения на шлифе

In the experimental studies of the structure of the special coating layer overlaid on metal applying gas-thermal spraying technique, one of the main methods is the study of polished specimen micrography. According to the computer analysis of microphotographs, it is possible to obtain the distribution function of inhomogeneities in the sample. However, since micrography is a flat image, the resulting function will be two-dimensional, whereas in a real sample, the distribution of defects is described by a three-dimensional function. In this paper, the problem of the space function recovery for the distribution of defects in a gas-thermal coating is viewed on the basis of the analysis of polished specimen micrography. The actual inclusion of an irregular shape is replaced by an effective three-axis ellipsoid. The problem is solved in the general form of reduction of the space function f of inhomogeneities distribution according to their distribution function f P on the cross - sectional plane P, which includes some integral transformation I. It is shown that in the special case of spherical particles, the inversion I^(-1) exists and is an integral transformation of the same type as I. The space distribution of spherical particles is also viewed, which does not depend on the longitudinal coordinate z, where particle sizes are limited at each point by a function R(x,y), depending on the coordinates. This distribution is suitable in its essense to the stationary spraying technology, when in deep layers near the substrate, the coating material melts completely and forms a single melt, while closer to the surface and edges, the parts that are not completely melted form inclusions of noticeable sizes. The reduction of the Fuller distribution law, used to optimize the granulometric composition of powder materials, is viewed as a second example. It is found that the reduction of the density of the ellipsoid distribution function to the section of a flat strip transfers the density of the distribution of centers as original, and the product of Fuller distributions times independent parameters is transformed into the product of distributions times the opposite degree parameters and also the previous values of the parameters of the ellipsoid

Maxwell homogenisation methodology for evaluation of effective elastic constants of weakly-nonlinear particulate composites

The far-field methodology, developed by J. C. Maxwell in 1873 for the evaluation of the electrical conductivity of a particle-reinforced material, is utilised to estimate the effective third order elastic constants of composite media containing a random distribution of spherical particles. The results are explicit analytical relationships derived using a perturbation solution, that are in a broad agreement with previous studies employing different homogenisation schemes. In contrast to other homogenisation schemes, Maxwell's methodology relies only on the far-field asymptotics. Therefore, the methodology may be more suitable for the evaluation of effective mechanical and physical properties of composites where the far-field asymptotics are known or can be derived. The main fundamental result of this work is the first demonstration that the Maxwell methodology may be applied to weakly nonlinear problems. Therefore, it can offer a new, simple method to analyse homogenisation problems in many other fields.

Tunable Mie resonance in complex-shaped gadolinium niobate

Nanoscale particles described by Mie resonance in the UV–vis–NIR region are in high demand for optical applications. Controlling the shape and size of these particles is essential, as it results in the ability to control the wavelength of the Mie resonance peak. In this work, we study the extensive scattering properties of gadolinium niobate particles with complex bar- and cube-like shapes in the UV–vis–NIR region. We perform our experimental analysis by characterizing the morphology and extinction spectra, and our theoretical study by implementing a Mie scattering model for a distribution of spherical particles. We can accurately model the size distribution and extinction spectra of complex shaped particles and isolate the contribution of aggregates to the extinction spectra. We can separate the contributions of dipoles, quadrupoles, and octupoles to the Mie resonances for their respective electric and magnetic parts. Our results show that we can tune the broad Mie resonance peak in the extinction spectra by the nanoscale properties of our system. This behavior can aid in the design of lasing and luminescence-enhanced systems. These dielectric gadolinium niobate submicron particles are excellent candidates for light manipulation on the nanoscale.

A discrete element method to model coating layer mechanical properties with bimodal and pseudo-full particle size distributions

The mechanical properties of paper coating layers are important in converting operations such as calendering, printing, and folding. While several experimental and theoretical studies have advanced our knowledge of these systems, a particle level understanding of issues like crack-at-the-fold are lacking. A discrete element method (DEM) model is used to describe bending and tension deformations of a coating layer. The particles in the model are either bimodal distributions or pseudo-full particle size distributions of spherical particles. The impact of particle size distribution on the predicted mechanical properties of the coating layer is reported. Inputs to the model include properties of the binder film and the binder concentration. The model predicts crack formation as a function of these parameters and also calculates the modulus, the maximum stress, and the strain-to-failure. The simulation results are compared to previous experimental results. Reasonable predictions were obtained for both tensile and bending for a range of latex-starch ratios and at various binder concentrations. The influence of particle packing density on mechanical properties is reported.

Structural, magnetic, and antibacterial activity of the pure, Zn-doped, and Zn-doped/sugar-assisted coprecipitation synthesized semicrystalline Co3O4 compound

Undoped, Zn-doped, and Zn-doped/sugar-assisted semi-crystalline structures of Co3O4 were made by introducing a facile precipitation approach. The synthesized compounds were tested for surface characteristics, magnetic properties, and antibacterial activity. Powder X-ray diffraction (XRD) analysis confirmed semi-crystalline behavior and spinel structure formation in all synthesized compounds. Using scanning electron microscopy (SEM) characterization, microstructure formation along with the large agglomeration of spherical particles, uniform distribution of spherical particles, and spherical-flake-like particle structures were noticed for the pure, Zn-doped, and Zn-doped/sugar-assisted Co3O4 samples, respectively. From the vibration sample magnetometry (VSM), Zn-doped/sugar-assisted Co3O4 was found to have relatively lower saturation magnetization when compared to pure Co3O4 and Zn-doped Co3O4 material. The antibacterial performance of the synthesized compounds against the bacteria Escherichia coli (E.coli) and Staphylococcus aureus (S. aureus) has been tested. The above-mentioned germicidal responses showed a relatively larger inhibition zone for the Zn-doped and Zn-doped/sugar-assisted Co3O4 compared to the undoped Co3O4 sample. The obtained diameter inhibition zone values of all synthesised compounds are comparable to the standard positive and negative control.

Magnetic properties and self‐heat behaviors of core@shell structured MnFe2O4@Fe3O4 magnetic nanoparticles

AbstractIn this work, a facile solvothermal synthesis of MnFe2O4 nanoparticles is followed by an easy and reproducible process to envelop the synthesized MnFe2O4 nanoparticles with iron oxide nanoparticles using ethanol and ethylene glycol as solvents. All prepared MnFe2O4 nanoparticles show a homogenous distribution of spherical particles with an average particle size between 12 and 16 nm. The encapsulation process of MnFe2O4 nanoparticles does not affect their homogenous distribution with a very thin layer of Fe3O4 on the shell structure. The magnetic properties showed a superparamagnetic character with enhanced magnetic properties of MnFe2O4@Fe3O4 compared to pure MnFe2O4, which has been verified by magnetization and electron spin resonance. The heating efficiency of the prepared samples was evaluated in terms of the specific loss power using the calorimetric method. The synthesized MnFe2O4 nanoparticles show a significantly high value of about 72 W/g, which got doubled in the core@shell structure and reached 140 W/g at 189 kHz and 10kA/m of the magnetic field.

Production of spherical TiAl alloy powder by copper-assisted spheroidization

A copper-assisted spheroidization method was developed for preparing spherical intermetallic compound TiAl powder. By introducing copper into TiAl alloy, the brittle L21 Heusler structure TiAlCu2 alloy with low melting point (1050 °C) was produced. After preparing the spherical TiAlCu2 powder through solid–liquid interface de-wetting method, the porous TiAl alloy sphere with atomic ratio about 1:1 was prepared by dealloying the Cu element. Finally, the spherical TiAl alloy powder was prepared by sintering and deoxygenation. Compared with the current mature technology for preparing the spherical TiAl alloy powder, the size distribution of spherical particles can be easily regulated, which can meet the requirements for high-quality additive manufacturing technology. We believe that this method provides a new idea for preparing the spherical TiAl alloy powder and other spherical porous alloys.

Spherical particles design of vanillin via crystallization method: Preparation, characterization and mechanism

Vanillin is a natural flavor and is widely used in the fields of medicine, food and optoelectronics. However, the stable form I of vanillin usually shows needle or fiber-like morphology during crystallization, and it has poor powder performance (flowability, bulk density, dissolution rate, etc.), which further limits its applications. In this work, to improve the powder performances of vanillin, the spherical crystals were designed and prepared via spherical agglomeration method, and the spherical particles were systematically characterized using polarized light microscopy (PLM), particle size instrumentation, powder X-ray diffraction (PXRD) and Fourier infrared transform spectroscopy (FTIR). Meanwhile, the effects of BSR (Vbridging liquid:Vsolute), agitation rate and surfactant on the morphology and particle size distribution of spherical particles were analyzed to determine the optimal operating conditions for the spherical crystallization of vanillin as well as its formation mechanism and to improve the powder performance of the products. In addition, the multicomponent spherical particles of vanillin-salicylic acid obtained by crystal co-agglomeration (CCA) meet the formulation requirements in terms of morphology and particle size, which also enhance the dissolution rate of vanillin.

Utilization of Olive Pomace in Green Synthesis of Selenium Nanoparticles: Physico-Chemical Characterization, Bioaccessibility and Biocompatibility.

Olive pomace extract (OPE) was investigated as a potential surface modifier for the development of the green synthesis process of selenium nanoparticles (SeNPs). In order to evaluate them as potential nutraceuticals, the obtained nanosystems were characterized in terms of size distribution, shape, zeta potential, stability in different media, gastrointestinal bioaccessibility and biocompatibility. Systems with a unimodal size distribution of spherical particles were obtained, with average diameters ranging from 53.3 nm to 181.7 nm, depending on the type of coating agent used and the presence of OPE in the reaction mixture. The nanosystems were significantly affected by the gastrointestinal conditions. Bioaccessibility ranged from 33.57% to 56.93% and it was significantly increased by functionalization of with OPE. Biocompatibility was investigated in the HepG2 and Caco2 cell models, proving that they had significantly lower toxicity in comparison to sodium selenite. Significant differences were observed in cellular responses depending on the type of cells used, indicating differences in the mechanisms of toxicity induced by SeNPs. The obtained results provide new insight into the possibilities for the utilization of valuable food-waste extracts in the sustainable development of nanonutraceuticals.

Effective elastic properties of a weakly nonlinear particulate composite

The fundamental problem of finding the effective linear and nonlinear elastic properties of a particulate composite subjected to finite elastic deformations is solved when the matrix and particulate phases are assumed to be weakly nonlinear. Weak nonlinearity is adequate to describe common engineering materials and composites loaded in the elastic regime. A nonlinear analogue of the Eshelby solution for the axisymmetric deformation of spherical particles is derived. Based on this solution, explicit asymptotic expressions for the effective linear and third-order (nonlinear) elastic moduli are derived in the case of a dilute distribution of spherical particles based on a general homogenisation methodology proposed by Hill. It is demonstrated that the current solutions correctly recover well-known relationships for the linear material properties of particulate composites as well as previously derived expressions for the effective nonlinear properties for certain special cases considered previously (e.g. hydrostatic loading, and a neo-Hookean matrix containing voids). The obtained theoretical results also agree with limited experimental data available in the literature.

Using data science to locate nanoparticles in a polymer matrix composite

Structural polymers such as epoxy are commonly reinforced with nano-sized reinforcement particles to increase the toughness and thermo-mechanical properties. Although qualitative measurements can be made to examine particle distribution on a scratched or abraded nanocomposite surface, it is difficult to quantify the three-dimensional locations of the particles relative to the visible surface. In this investigation, we developed a method that combines experimental data obtained from atomic force microscopy (AFM), data science, and continuum micromechanics to discover the 3D position of ∼142 nm diameter nanosilica (NS) particles relative to an abraded surface. Finite element analysis was used to develop a training set of modulus values as a function of NS particle position relative to the surface of the polymer. Bayesian optimization was then used to determine the particle position(s) by minimizing the error between simulated and experimental modulus (AFM) contours. The algorithm can consistently predict particle positions within 3 nm of the actual known positions in synthetically created AFM data. We implemented the algorithm on experimental AFM data to create simulated modulus contours that partially reproduce key features present in an experimental modulus contour. This method provides a powerful tool to map spherical particle distribution in a 3D space, allowing better processing-structure-property understanding that can arise from resin chemistry variations, surface functionality, processing conditions, and nanofiller particle properties.

Derivation of Equations for a Size Distribution of Spherical Particles in Non-Transparent Materials

This paper presents a new proposition on how to derive mathematical formulas that describe an unknown Probability Density Function (PDF3) of the spherical radii (r3) of particles randomly placed in non-transparent materials. We have presented two attempts here, both of which are based on data collected from a random planar cross-section passed through space containing three-dimensional nodules. The first attempt uses a Probability Density Function (PDF2) the form of which is experimentally obtained on the basis of a set containing two-dimensional radii (r2). These radii are produced by an intersection of the space by a random plane. In turn, the second solution also uses an experimentally obtained Probability Density Function (PDF1). But the form of PDF1 has been created on the basis of a set containing chord lengths collected from a cross-section.The most important finding presented in this paper is the conclusion that if the PDF1 has proportional scopes, the PDF3 must have a constant value in these scopes. This fact allows stating that there are no nodules in the sample space that have particular radii belonging to the proportional ranges the PDF1.

Correction to: Non-linear Transfer Functions for Accurately Estimating 3D Particle Size, Distribution, and Expected Error from 2D Cross Sections of a Lognormal Distribution of Spherical Particles

Accurately estimating the mean size of features within an opaque material using only 2D observations is a common requirement in the materials and medical communities. Attempting to employ numerical methods to obtain an accurate estimate of the full 3D size distribution, which is often important for calculating structure-dependent material properties, is substantially more challenging. This paper circumvents the error propagation issues observed with classical numerical approaches, such as those formulated by Saltikov, Johnson, and Schwartz, through comparison of two calculation methods: (i) the direct simulation of synthetic particles and (ii) inversion of the conventional Saltikov analysis. Each method was used to generate dispersions whose 3D particle diameters followed lognormal distributions of varying shape parameters; the mean and variance were then predicted for 2D cross-sectional measurements. Parameters from both the 2D and 3D distributions were analytically coupled to produce a set of equations for accurately transforming cross-sectional observations into estimates of the full 3D distributions. Accuracy of the 2D-to-3D transformation is, for the first time, characterized as a function of the population size and measurement resolution. Specifically, included figures allow for rapid conversion from 2D to 3D metrics with the corresponding margin of error. The Inverse Saltikov method is shown to provide superior transformation accuracy for the idealized cases of lognormally distributed and randomly dispersed spherical particles when compared to either the Direct Simulation method or classical numerical approaches.

Influence of particle non-dilute effects on its dispersion in particle-laden blast wave systems

Even though the interaction of blast waves with dense particle distributions is ubiquitous in nature and in industry, the underlying physics of the multiphase system evolution is not clearly understood. A canonical multiphase system composed of an embedded monodisperse distribution of spherical particles in a spherical, high-energy gaseous charge is studied numerically using an Eulerian–Lagrangian approach to elucidate the role of non-dilute particle effects on the dynamics of the two-phase flow system. The direct simulation Monte Carlo method is modified to model inelastic particle–particle collisions and to model the gaseous flow inter-leaving through complex structures of monodisperse dense distributions of spherical particles to obtain parameters that are fit to semi-empirical particle cloud drag laws that account for aerodynamic interactions. The study reveals that inter-particle collisions decrease the total particle kinetic energy at early stages of the particle-laden blast wave system evolution, but near-particle interaction increases the particle kinetic energy at this stage. In contrast, at later stages of evolution, collisions tend to retain more kinetic energy, while the aerodynamic interactions tend to dissipate particle kinetic energy.

Spheroidization of borosilicate glass powder by RF induction coupled plasma

The International Simple Glass (ISG) spherical particles were prepared by Ar–H2 radio-frequency (RF) plasma, the effect of experimental parameters on the volatilization and size distribution of spherical particles was studied. The results show that the spherical powders can be obtained by RF plasma. The spheroidized powders (112 μm) have a smaller diameter than starting particles (124 μm). The high spheroidization (98%) was achieved under low flow rate of carry gas and low feed rate. In addition, the volatilization of B2O3 and Na2O are 23.48% and 56.36%, respectively. The higher feed rate and flow rate of carry gas, the lower volatilization of B2O3 and Na2O and well-spheroidization rate. Meanwhile, the particle surface is not completely smooth at low flow rate of carry gas. The distribution of elements was studied by Electro-probe Microanalyzer (EPMA), which shows the distribution of element is nearly homogeneous that provides a possibility for subsequent research.

Development of margination of platelet-sized particles in red blood cell suspensions flowing through Y-shaped bifurcating microchannels.

In the blood flow through microvessels, platelets exhibit enhanced concentrations in the layer free of red blood cells (cell-free layer) adjacent to the vessel wall. The motion of platelets in the cell-free layer plays an essential role in their interaction with the vessel wall, and hence it affects their functions of hemostasis and thrombosis. We aimed to estimate the diffusivity of platelet-sized particles in the transverse direction (the direction of vorticity) across the channel width in the cell-free layer by in vitro experiments for the microchannel flow of red blood cell (RBC) suspensions containing platelet-sized particles. Fluorescence microscope observations were performed to measure the transverse distribution of spherical particles immersed in RBC suspensions flowing through a Y-shaped bifurcating microchannel. We examined the development of the particle concentration profiles along the flow direction in the daughter channels, starting from asymmetric distributions with low concentrations on the inner side of the bifurcation at the inlet of the daughter channels. In daughter channels of 40 μm width, reconstruction of particle margination revealed that a symmetric concentration profile was attained in ∼30 mm from the bifurcation, independent of flow rate. We presented experimental evidence of particle margination developing in a bifurcating flow channel where the diffusivity of 2.9-μm diameter particles was estimated to be ∼40 μm2/s at a shear rate of 1000 s-1 and hematocrit of 0.2.

Study of particle lifting mechanisms in an electrostatic discharge plasma

Although particle-laden electrostatic discharges are widely used in research as well as in industrial applications, the mechanisms of particle lifting for a particle initially at rest in such highly unsteady flows are not well understood. A multiphase plasma flow is modeled by solving the continuum conservation equations and particles as discrete entities in a Lagrangian approach. The gas phase solver is used to study the generation of shock waves and the high temperature plasma kernel. A one-way coupling approach between the two phases is used and various Lagrangian sub-models are developed to study the particle phase evolution in the system. Comparison with shock tube measurements where a planar shock wave perpendicular to the shock tube wall interacts with particles residing on the wall showed that the predominant mechanism of particle lifting is the Saffman force generated on particles due to velocity gradients in the gas boundary layer. A second configuration with an overhead spherical blast wave generated by an electrostatic discharge (ESD) interacting with a polydisperse distribution of spherical particles placed at three wall-electrode distances was considered. The predicted particle lifting heights and velocities are found to compare well with measurements in an ESD configuration initiated by the dielectric breakdown of ambient air.

On the Macroscopic Response and Field Statistics in Particulate Composites With Elasto-Plastic Phases and Random Microstructures

Abstract In this article, we carry out a theoretical investigation of the macroscopic response and field statistics in two-phase particulate composites with elasto-plastic constituents and random microstructures under cyclic loading conditions. To this end, we make use of the “incremental variational homogenization” (IVH) procedure of Agoras et al. (2016, “Incremental Variational Procedure for Elasto-Viscoplastic Composites and Application to Polymer- and Metal-Matrix Composites Reinforced by Spheroidal Elastic Particles,” Int. J. Solid Struct., 97–98, pp. 668–686) and corresponding unit cell finite element simulations. Results are obtained for statistically isotropic distributions of spherical particles and for “spheroidal distributions” of spheroidal particles. It is shown analytically that the IVH estimate of Agoras et al. and that of Lahellec and Suquet (2013, “Effective Response and Field Statistics in Elasto-Plastic and Elasto-Visco-Plastic Composites Under Radial and Non-Radial Loadings,” Int. J. Plasticity, 42, pp. 1–30) are equivalent. In addition, it is illustrated by means of specific numeral comparisons that the IVH estimate is also equivalent (to within numerical accuracy) to the corresponding estimates of Idiart and Lahellec (2016, “Estimates for the Overall Linear Properties of Pointwise Heterogeneous Solids With Application to Elasto-Viscoplasticity,” J. Mech. Phys. Solids, 97, pp. 317–332) and Lucchetta et al. (2019, “A Double Incremental Variational Procedure for Elastoplastic Composites With Combined Isotropic and Linear Kinematic Hardening,” Int. J. Solid Struct., 158, pp. 243–267). Furthermore, it is shown in the context of specific exact results for composite materials with lamellar microstructures that the elastic–plastic coupling and the Bauschinger effect are the macroscopic manifestations of the incompatibility of the local elastic strains. Local strain hardening is incorporate in the IVH model. The predictions of the IVH model for the macroscopic response of particulate composites are found to be in good agreement with the corresponding numerical results, in general. For the extreme cases of rigidly reinforced composites and porous materials, however, the IVH model fails to capture the elastic–plastic coupling and the Bauschinger effect. The underlying reasons for this shortcoming are discussed and a strategy toward the improvement of the IVH model is proposed.