Submicron-sized Particles Research Articles

Carbon primer layer morphological effect on the lithium manganese iron phosphate positive electrode performances for lithium-ion batteries

The use of lithium manganese iron phosphate (LMFP) electrodes is important for enhancing the energy density of phosphate-based positive electrodes. However, their practical application is hindered by the deteriorating collector–electrode interface caused by submicron-sized particles with carbon-coated surfaces. The morphology of these carbon particles affects the efficiency of the primer layer, despite its role in strengthening the electrical contact between LMFP and the aluminum (Al) current collector. Incorporating carbon nanotube (CNT)-type carbon into the primer layer weakens the electrical connection between the electrode mass and current collector, indicating that CNT-coated Al does not effectively reduce contact resistance. In contrast, the planar shape of graphene-type carbon provides a more effective connection between LMFP and the Al plate, resulting in minimal contact resistance. This improvement in contact resistance enhances cycleability by significantly reducing polarization during cycling, which prevents electrolyte decomposition on the LMFP surface. Given the significant impact of carbon morphology on interfacial contact, it is essential to rationally control the morphology of the carbon primer layer to optimize the properties of the positive electrode.

Comprehensive Characterization of Bi1.34Fe0.66Nb1.34O6.35 Ceramics: Structural, Morphological, Electrical, and Magnetic Properties

Recent research in solid-state physics and materials engineering focuses on the development of new dielectric materials, with bismuth-based pyrochlores being already extensively applied in communications technology for their excellent dielectric properties and relatively low sintering temperatures. Herein, the structural, morphological, electrical, and magnetic properties of Bi1.34Fe0.66Nb1.34O6.35 ceramic, prepared by the sol–gel method and sintered at 500 °C, are investigated. The Rietveld refinement of the XRD pattern showed a cubic phase belonging to the space group Fd-3m and a crystallite size of 42 nm. Transmission electron microscopy further confirmed the crystallite size and the homogeneous distribution of Bi, Fe, Nb, and O elements, as evidenced by high-angle annular dark field imaging and STEM-EDX mapping. The morphology of the sample, assessed by scanning electron microscopy, is characterized by submicron-sized spherical particles. Dielectric spectroscopic studies revealed that the dielectric properties, strongly influenced by frequency and temperature, indicate the material’s potential for energy storage due to lower dielectric loss compared to the dielectric constant. The observed relaxation phenomena, confirmed through variations in dielectric loss and loss tangent, highlight the influence of grain boundaries and temperature on electron hopping and charge carrier dynamics. Using SQUID magnetometry, we identified two distinct magnetic phases. The primary phase, corresponding to the Bi1.34Fe0.66Nb1.34O6.35 ceramic, exhibits an antiferromagnetic behavior below its Néel temperature at around 8.8 K. A secondary high-Curie temperature ferrimagnetic phase, likely vestigial maghemite and/or magnetite, was also detected, indicating an estimated fraction below 0.02 wt.%.

Sol-gel synthesis, structure and adsorption properties of LiMgxMn(2-x)O4 (0 ≤ x ≤ 0.7) Oxides

Lithium manganese оxides with a spinel structure LiMgxMn(2–x)O4, doped with Mg2+ ions in the range 0 ≤ x ≤ 0.7, were obtained by sol-gel synthesis. Phase composition and morphology of obtained оxides were studied by using X-ray phase analysis and scanning electron microscopy. It is shown, that in the studied range 0 ≤ x ≤ 0.7 Mg-doped lithium manganese оxides saved the structure of the original cubic spinel LiMn2O4, while an increase in parameter a was observed from 8.175 to 8.309 Å and average crystallite size practically unchanged (30–36 nm). Samples of the initial LiMn2O4 and Mg-doped spinels were represented by prismatic particles of submicron (0.1–0.2 µm) and micron (1.0–3.0 µm) sizes, respectively. The effect of the adsorbent dose (0.05–0.3 g/l) and pH (3.0–13.0) of the solution on the adsorption efficiency was studied. The adsorption isotherms of the LiMg0.3Mn1.7O4 samples were described by the Langmuir monomolecular adsorption equation. An increase in the temperature of the model solution from 25 to 45°C was accompanied by an increase in the maximum adsorption of the LiMg0.3Mn1.7O4 samples from 10.50 to 10.98 mmol/g, which indicates the endothermic nature of the adsorption process. The kinetics of adsorption was well described by a pseudo-second order equation, which indicates the occurrence of chemical interaction during the adsorption process.

Fully Atom-Efficient Solvent-Mediated Biopolymer Manufacturing: A Base Case Illustrated with Macromolecular Surfactants Tailored to Stable Polymer-Water Interfaces.

This work introduces a novel 1-pot, 0-waste, 0-VOC methodology for synthesizing polymeric surfactants using acrylated epoxidized soybean oil and acrylated glycerol as primary monomers. These macromolecular surfactants are synthesized via reversible addition-fragmentation chain transfer (RAFT) polymerization, allowing for tunable hydrophilic-lipophilic balance (HLB) and ionic properties. We characterize the copolymers' chemical composition and surface-active properties, and evaluate their effectiveness in forming and stabilizing emulsions of semiepoxidized soybean oil and poly(acrylated epoxidized high oleic soybean oil). Comprehensive analyses, including gel permeation chromatography, nuclear magnetic resonance spectroscopy, dynamic light scattering, particle size distribution, zeta potential, and critical micelle concentration, provide detailed insights into the copolymers and the emulsions they form. The results demonstrate that the RAFT-polymerized surfactants offer long-lasting stability and effectively disperse both common oil-in-water emulsions and highly viscous and hydrophobic polymer latexes. These surfactants outperform traditional small molecule surfactants by reducing particle size and preventing phase separation, even over extended storage periods. Stable polymer-water interfaces are achieved through HLB control, tailored by monomer composition, and the final product requires no additional purification since polymerization occurs in liquid surfactants. While small molecules contribute to rapid micelle formation, the polymeric components enhance long-term stability through steric repulsion and slower dynamics. This method enables even the emulsification of polymers with submicron particle size, which ordinarily requires emulsion polymerization. Integrating biobased polymeric surfactants with advanced polymer processing techniques opens new possibilities for transforming highly hydrophobic polymers into latexes, facilitating downstream applications. This innovation enhances the environmental sustainability of surfactant production and broadens the potential for polymer emulsification technologies. Additionally, the integrated solution-processing approach demonstrated here can be applied to other emerging polymers, where judiciously selected nonvolatile solvents facilitate the polymerization and play a role in the final application.

Chemical synthesis, structural and magnetic properties of Al-doped neodymium orthoferrite

Crystalline and single phase of Al doped orthoferrite with stoichiometry NdFe1-xAlxO3 was synthesized by a hydrothermal method. The effect of Al doping on the structure features was investigated by powder X-ray diffraction (PXRD) technique. In this sense, Rietveld refinement was applied in refining the PXRD data. Scanning electron microscopy (SEM) was used to characterize the morphology. And from image analyses show a sub-micron particle size distributions for all samples. Using hydrothermal synthesis method, a micro-sized particle distribution is reached. Measurement of magnetic hysteresis loops showed that the highest coercivity (Hc) obtained was 5.2 kOe for the sample with x=2. Compared to previous results using sol-gel synthesis, the hydrothermal method used in this study showed improved magnetization properties.

Soft X-ray spectromicroscopic proof of a reversible oxidation/reduction of microbial biofilm structures using a novel microfluidic in situ electrochemical device

In situ electrochemistry on micron and submicron-sized individual particles and thin layers is a valuable, emerging tool for process understanding and optimization in a variety of scientific and technological fields such as material science, process technology, analytical chemistry, and environmental sciences. Electrochemical characterization and manipulation coupled with soft X-ray spectromicroscopy helps identify, quantify, and optimize processes in complex systems such as those with high heterogeneity in the spatial and/or temporal domain. Here we present a novel platform optimized for in situ electrochemistry with variable liquid electrolyte flow in soft X-ray scanning transmission X-ray microscopes (STXM). With four channels for fluid control and a modular design, it is suited for a wealth of experimental conditions. We demonstrate its capabilities by proving the reversible oxidation and reduction of individual microbial biofilm structures formed by microaerophilic Fe(II)-oxidizing bacteria, also known as twisted stalks. We show spectromicroscopically the heterogeneity of the redox activity on the submicron scale. Examples are also provided of electrochemical modification of liquid electrolyte species (Fe(II) and Fe(III) cyanides), and in situ studies of electrodeposited copper nanoparticles as CO2 reduction electrocatalysts under reaction conditions.

Sol-Gel Derived Alumina Particles for the Reinforcement of Copper Films on Brass Substrates.

The aim of this study is to provide tailored alumina particles suitable for reinforcing the metal matrix film. The sol-gel method was chosen to prepare particles of submicron size and to control crystal structure by calcination. In this study, copper-based metal matrix composite (MMC) films are developed on brass substrates with different electrodeposition times and alumina concentrations. Scanning electron microscopy (FE-SEM) with energy-dispersive spectroscopy (EDS), TEM, and X-ray diffraction (XRD) were used to characterize the reinforcing phase. The MMC Cu-Al2O3 films were synthesized electrochemically using the co-electrodeposition method. Microstructural and topographical analyses of pure (alumina-free) Cu films and the Cu films with incorporated Al2O3 particles were performed using FE-SEM/EDS and AFM, respectively. Hardness and adhesion resistance were investigated using the Vickers microindentation test and evaluated by applying the Chen-Gao (C-G) mathematical model. The sessile drop method was used for measuring contact angles for water. The microhardness and adhesion of the MMC Cu-Al2O3 films are improved when Al2O3 is added. The concentration of alumina particles in the electrolyte correlates with an increase in absolute film hardness in the way that 1.0 wt.% of alumina in electrolytes results in a 9.96% increase compared to the pure copper film, and the improvement is maximal in the film obtained from electrolytes containing 3.0 wt.% alumina giving the film 2.128 GPa, a 134% hardness value of that of the pure copper film. The surface roughness of the MMC film increased from 2.8 to 6.9 times compared to the Cu film without particles. The decrease in the water contact angle of Cu films with incorporated alumina particles relative to the pure Cu films was from 84.94° to 58.78°.

Extended Monte Carlo modeling for submicron particle size measurement under high light extinction conditions

The light extinction method (LEM) based on Lambert Beer's law (LB) is widely used to characterize particle size distribution (PSD) in multiphase flow. However, as the optical thickness increases with concentration, the phenomenon of multiple scattering is enhanced, potentially leading to reduced accuracy and a limited application range. In this study, an extended Monte Carlo-based light extinction model (EMC) was developed, which was initially employed to calculate and evaluate the impact of multiple scattering. Subsequently, it was used to predict the extinction spectrum that incorporates multiple scattering effects under varying concentrations. To validate the modeling, a compact setup was constructed to perform a series of experiments on polystyrene and silica dioxide (SiO2) suspensions. A differential evolution algorithm was also implemented for the inversion of PSD based on spectral content, with the incorporation of an improved coefficient matrix that considers multiple scattering effects. In comparison to the linear LB model, the EMC exhibits a markedly enhanced capacity in handling higher particle concentrations and improving measurement accuracy. For a 700 nm PS suspension, the particle size inversion error of the EMC can be kept within 4% (93.86% for the LB model) compared with the nominal value, even with an optical thickness of 5.

Innovative use of lipid mesophase dispersions for bisphenol A sequestration in water

HypothesisMesophase dispersions are promising colloids for removing micropollutants from water. We hypothesized that the complex internal nanostructure and tunable lipid/water interface amounts play a crucial role in absorbed quantities. Modifications in interfacial organization within the particles while trapping the micropollutant is assumed. ExperimentsWe formulated stable monolinolein-based dispersions with four types of mesophases (bicontinuous and micellar cubic, hexagonal, and fluid isotropic L2) by varying dodecane contents. The absorption of bisphenol A by these dispersions from water was monitored using molecular spectroscopy. At equilibrium, absorbed quantities by mesophase dispersions were compared to unstructured dodecane/water miniemulsions for two bisphenol concentrations. Structural changes during bisphenol incorporation were identified using small-angle X-ray scattering. FindingsLipid mesophase particles of submicron size showed greater bisphenol incorporation than dodecane/water miniemulsions, with cubosomes being most effective ones, absorbing twice as much as unstructured emulsions. Higher absorption levels are observed for more complex nanostructures with increased lipid/dodecane ratios. The incorporation of bisphenol affected the curvature of internal interfaces, potentially causing phase transitions and indicating that bisphenol settles at interfaces. Similar absorption levels in identical mesophases suggest a strong correlation between nano-structure and absorbed quantities.

Material Trends and Clinical Costings in Systematically Identified CDER‐Approved Nanomedicines

AbstractResearch into mechanisms and potential applications of nanomaterials in medicine has expanded steadily in recent decades, with increasing translational focus. Development costs, including for clinical trials, are often cited as factors limiting the translational viability of novel nanomedicines, especially compared to small new molecular entities (NMEs) and therapeutic biologics. Yet, to date, there has been no systematic investigation into the clinical programs or costs of translating and commercializing nanomedicines, nor a comparison to NMEs and therapeutic biologics, to support these claims. Here, nanomedicines approved by the United States Food and Drug Administration's Center for Drug Evaluation and Research (CDER) from 2011 to 2023 are systematically identified and categorized. Nanomedicines were identified as formulations where submicron particle size contributes to product function. Like biologics and NMEs, nanomedicines are most frequently approved for oncological indications. Notably, all anti‐cancer nanomedicines are indicated to treat orphan diseases, which is representative of the potential for nanomedicines to occupy pharmaceutical niches in treating diseases affecting smaller patient cohorts. The median estimated cost of pivotal trials for nanomedicines is 47% that of biologics and NMEs approved in the same timeframe. The findings indicate higher manufacturing costs in nanomedicine development may be mitigated by savings elsewhere, increasing translational viability.

Enhanced strength–ductility synergy of SiC particles reinforced aluminum matrix composite via dual configuration design of reinforcement and matrix

To overcome the strength-ductility conflict in particle reinforced aluminum matrix composites (PRAMCs), a novel dual configuration strategy of microstructure was proposed in this work. The dual configuration including both heterogeneous grain structure and hybrid reinforcements was obtained by powder metallurgy, which was designed as submicron-sized SiC particles (SiCsm)/Al and micron-sized SiC particles (SiCm)/2024Al components. Representative alternating coarse grain (CG) bands containing SiCm and ultra fine grain (UFG) bands with dispersed SiCsm were revealed in microstructural characterizations. Compared to corresponding homogeneous composites with the same fraction particles, the dual configuration composite achieved simultaneous enhancement in strength and ductility and remained a comparable Young’s modulus of 98GPa, which represented 442 MPa in yield strength, 590 MPa in ultimate strength and 8.7 % in fracture elongation. The extra strength provided by hetero-deformation induced (HDI) strengthening is a potential dominant strengthening mechanism. The intrinsic toughening mechanisms primarily contribute to HDI strain hardening and enhanced dislocation accumulation capacity, while the extrinsic toughening mechanisms presumably attribute to more uniform microcrack distribution and blunting effect of CG zones on cracks. Our work provides a feasible route including ball milling and powder assembly to preparate high-modulus aluminum matrix composites for strength-ductility balance design.

Particle Matter determination in Biosimilar Parenteral Product by the Application of Dynamic Light Scattering (DLS) Followed by Statistical Evaluation

Particulate matter in parenteral dosage forms can emerge from numerous causes, external, intrinsic, as well as inherent within the product, with a special emphasis on biopharmaceuticals. Aqueous impurities, pharmaceutical precipitates, dirt, glass, rubber, pollutants from the environment, fibres, and various other insoluble materials are all common sources of particulates. When assessing the possible harm to patients, particulate matter size is a crucial issue to consider. Particles as fine as 2 μm overall diameter were found related with microthrombi development. The DLS (Dynamic Light Scattering) technique has been used to measure and control the subvisible particulate particles in biopharmaceutical parenteral drug products since the technique can measure the submicron particle size in the parenteral formulation. The purpose of using DLS is to measure and control the subvisible particles in a biopharmaceutical formulation. A generic biopharmaceutical product viz. Calcitonin Salmon injection was used for particulate matter analysis by using Dynamic Light Scattering. DLS is a non-invasive method for detecting the size of suspended particles as well as molecules which is used for the control and optimization of processes, and the improvement of product quality and performance by analysing the time-dependence in regard to intensity of the dispersed light (auto correlation) to determine the diffusion speed (Brownian motion) of particles/molecules, and subsequently determine the hydrodynamic size. Keywords: Particulate matter; DLS; Biosimilars; Parenteral dosage forms

Turbostratic carbon nanofibers produced from C2HCl3 over self-dispersing Ni-catalyst doped with W and Mo

In this research, a self-dispersing 92Ni-4Mo-4W catalyst showing high productivity towards the H2-assisted synthesis of turbostratic carbon nanofibers was proposed. The effect of reaction temperature on the efficiency of 92Ni-4Mo-4W alloy in the decomposition of trichloroethylene was studied. It was found that in the temperature range of 580–620 °C, the most rapid destruction of the initial alloy followed by the growth of carbon material is realized. This is confirmed by the minimum induction period (9–11 min) and the maximum carbon yield (95–107 g/gcat). As revealed, the catalytically active particles of submicron size contain uniformly distributed Ni, Mo, and W. It is demonstrated that the decomposition of trichloroethylene over the 92Ni-4Mo-4W catalyst results in the formation of a turbostratic carbon material with a segmented structure, containing a minimum quantity of amorphous carbon and possessing high textural characteristics (specific surface area of 330–410 m2/g; pore volume of 0.48–0.58 cm3/g).

Effects of homogenization temperature on microstructure, mechanical properties and corrosion behavior of binary Zn-Mn alloys extruded at different temperatures

In order to optimize the mechanical properties (MPs) of biodegradable Zn-based alloys, many researches have been conducted. However, the effect of homogenization treatment before the plastic deformation process on the MPs of biodegradable Zn-based alloys has not received sufficient attention, although it has been demonstrated to play an important role in improving the MPs of Al- and Mg-based alloys. In this work, as-cast Zn-0.8 wt% Mn alloys were firstly homogenized at two different temperatures (330 and 390 °C) followed by quenching and then extruded at three different temperatures (170, 230 and 300 °C). This work revealed the effects of homogenization temperature (HT) on microstructure, MPs and corrosion behavior of Zn-0.8 wt% Mn alloys extruded at different temperatures. The results showed that compared to the alloy homogenized at 330 °C (HT330), the alloy homogenized at 390 °C (HT390) has less precipitation of micron-sized MnZn13 particles in the homogenization process. During the subsequent extrusion processes at 170 and 230 °C, more submicron-sized MnZn13 particles are precipitated and finer Zn grains are formed in the HT390 alloys than in the HT330 alloys. Correspondingly, the two extruded HT390 alloys exhibit elongations of up to 133 % and 86 %, respectively, which are much higher than the 71 % and 65 % of the two extruded HT330 alloys. However, when the extruding temperature is elevated to 300 °C, high HT causes decrease in the fraction of both the micron- and submicron-sized MnZn13 particles as well as coarsening of Zn grains, followed by an increase in the strength of the as-extruded alloy. In addition, high HT is conductive to improving the corrosion resistance of the as-extruded alloys regardless of the extrusion temperature.

Identification of solid phase speciation of trace elements in dust dry deposition using focused ion beam and selected area electron diffraction

BackgroundFew studies have been conducted to identify solid phase speciation of trace elements within the interior of airborne particles, although the adverse effects of ambient particles are closely related to the speciation of toxic elements and therefore the identification of chemical binding sites and solid phase associations is essential for assessing the impacts of trace elements in ambient air on environmental quality and human health. ObjectiveA combined use of focused ion beam scanning electron microscopy (FIB-SEM) and selected area electron diffraction (SAED) patterns from transmission electron microscopy (TEM) was applied with an energy dispersive X-ray spectroscopy (EDS) to investigate the solid phase speciation of trace elements within the interior of dust dry deposition obtained from an urban area. ResultsThe study results using the high-resolution microscopic techniques for the characterization of nano- and micron-sized particles revealed lead chromate for Pb and Cr6+, barite for Ba, rutile for Ti, and calcite, gypsum, and quicklime for Ca within the carbon matrix, implying their traffic-related sources. Fe oxides were observed for Fe, Mn, Ni, and Cr3+, with cerianite and Fe-La alloys for rare earth elements (REEs). ConclusionsThree types of anthropogenic sources were inferred based on the morphology and texture of the solid phases, as well as their primary usage: traffic road marking paints for Pb, Cr6+, Ba, and Ti, cement materials for Ca, and industrial activities for Fe, Mn, Ni, Cr3+, and REEs. The presence of submicron-sized toxic metal-bearing particles in dust dry deposition indicated that the toxic metals (i.e., Pb, Cr6+) can penetrate into the respiratory system along with the nanoparticles. The study results demonstrate that the solid phase speciation of trace elements detected using FIB-SEM and TEM-SAED can be effectively utilized for the identification of sources and the assessment of chemical toxicity of atmospheric dust.

Nano- and Submicron-Sized TiB2 Particles in Al–TiB2 Composite Produced in Semi-Industrial Self-Propagating High-Temperature Synthesis Conditions

Nano- and Submicron-Sized TiB2 Particles in Al–TiB2 Composite Produced in Semi-Industrial Self-Propagating High-Temperature Synthesis Conditions

Formulation development of nanostructured lipid carrier-based nanogels encapsulating tacrolimus for sustained therapy of psoriasis

The goal of this study was to formulate tacrolimus nanogel based on nanostructured lipid carrier (NLC) in order to improve the efficacy, aesthetic, and patient compliance for the treatment of psoriasis. The microemulsion method was used to create phase diagrams and NLCs were prepared using points obtained from the microemulsion region and characterized. The gelling agent carbopol was used to develop an NLC-based nanogel. The pH, drug assay, viscosity, spreadability, and in vitro release of the nanogel, were evaluated. Ex vivo cytotoxicity of the formulation was assessed in murine fibroblast cells. Oxazolone and imiquimod models of psoriasis were used to assess the effectiveness of the nanogel. The NLCs exhibited a submicron particle size of 320 ± 10 nm, a low polydispersity index (<0.3), and a zeta potential of −19.4 mV. Morphological analysis revealed spherical nanoparticles with an encapsulation efficiency of 60 ± 3 %. The nanogel maintained a pH of 6.0 ± 0.5 and possessed a remarkable drug content of 99.73 ± 1.4 %. It exhibited pseudoplastic flow behaviour, ensuring easy spreadability, and demonstrated sustained drug release exceeding 90 % over a 24-hr period. Ex vivo cytotoxicity assessments revealed that the nanogel was safe because no cell death was induced. Nanogel resolved psoriatic blisters, was non-irritating and improved skin elasticity. The favorable properties, safety profile, and remarkable efficacy show the potential of the nanogel as a patient-friendly and effective therapeutic option for psoriasis treatment.

Comparison of a thickness-tapered channel in flow field-flow fractionation with a conventional channel with flow rate programming

The thickness-tapered channel structure in flow field-flow fractionation (FlFFF), recently introduced by constructing a channel with a linear decrease in thickness along its length, demonstrated effectiveness in steric/hyperlayer separation of supramicron particles with improvements in separation speed, elution recovery, and an expanded dynamic size range of separation. In this study, we conducted a comparative analysis of the performance between the impact of field (or crossflow rate) programming or outflow rate programming for the separation of polystyrene latex standards (50 ∼ 800 nm) with a conventional channel having uniform thickness and a thickness-tapered channel without programming. Outlet flow rate and crossflow rate conditions were also varied. Although the particle size resolution of the tapered channel does not surpass that of field programming in uniform thickness channel, it achieves higher-speed separation without a significant loss of resolution and without the need for a complex flow controller system even at a low outflow rate condition. Furthermore, it yielded an improved resolution for particles close to the steric transition regime (400 ∼ 600 nm) in the normal mode of separation. Due to the continuous increase in mean flow velocity down the channel, the tapered channel exhibits flexibility in separating submicron-sized particles at high crossflow rate conditions or low outflow rate conditions, of which the latter can be advantageous when coupled with mass spectrometry in a miniaturized setup.

Kinetic Regularities of the Synthesis of Silica Nanoparticles by Heterogeneous Hydrolysis of Tetraethoxysilane Using L-Arginine as a Catalyst

Abstract The kinetics of the synthesis of silica nanoparticles (&lt;50 nm) has been studied under the conditions of heterogeneous hydrolysis of tetraethoxysilane (TEOS) using L-arginine as an alkaline catalyst. The rates of silica formation have been determined in a temperature range of 10–95°C at catalyst concentrations of 6–150 mM. It has been shown that the activation energy of the process depends on catalyst concentration and varies in a range of 21.5–13.9 kJ/mol, while decreasing linearly with increasing concentration of L-arginine in the system. The criterion of maintaining the monodispersity has been estimated for SiO2 particles being grown “onto seeds.” The density of submicron-sized silica particles has been experimentally determined as depending on the annealing temperature. Within a temperature range of 200–1000°C, the particle density varies from 2.04 to 2.20 g/cm3.

Mathematical Simulation of the Influence of Acoustic on the Efficiency of PM 2.5 Coagulation

The particles of micron and submicron sizes (PM 2.5 and less) in gas environments pose a significant danger to humanity due to the emergence of specific and very dangerous diseases of the cardiovascular, respiratory, and immune systems of the human body. Such particles are the most difficult to detect; therefore, their effects on human health have only been discovered in recent decades. Classical ultrasonic coagulation by sinusoidal action turns out to be ineffective for PM 2.5 due to the peculiarities of the physical mechanisms of hydrodynamic and orthokinetic interaction realized in gaseous media. This article presents a theoretical justification for choosing ways to increase the efficiency of ultrasonic coagulation of PM 2.5 by creating special conditions under which nonlinear disturbances of the velocity and pressure of the gas phase in the ultrasonic field occur. The authors performed simulations of ultrasonic coagulation under nonlinear disturbances of the velocity (vortex) and the pressure (shock waves), which has numerical difficulties due to the instability of existing methods. As a result of the numerical analysis, the possibility of increasing the coagulation rate of particles in the submicron size range up to limit values (13 times due to nonlinear pressure disturbances, and an additional increase of at least 2 times due to aerosol compaction in the vortex field of gas velocity) was shown.