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In this study, we developed Earth Fuller-based composites (EFBC) by incorporating varying mass fractions (2, 4, 6, and 8 wht %) of micron-sized Al2O3 and TiO2 particles. The microstructure of the prepared EFBC was analyzed using Bruker-Nova FE-SEM, operating at 5–30 kV. We investigated the thermal properties, including thermal conductivity (TC), thermal diffusivity (TD), and specific heat capacity (SHC) of the composites using a Thermal Constants Analyzer. The measurements were performed at temperatures ranging from 10 °C to 60 °C, with intervals of 10 °C. Results showed that increasing the weight percentage of Al2O3 and TiO2 in EFBC resulted in an 11% and 10% increment in thermal conductivity, respectively, at 30 °C. Interestingly, the thermal diffusivity exhibited a 9% increase with 6 wht % Al2O3 loading at 10 °C, while a 7% decrement was observed with 8 wht % TiO2 loading at 30 °C. Surprisingly, at 8 wht % Al2O3 particles, thermal diffusivity increased significantly by 195% at 30 °C. The specific heat capacity of EFBC with Al2O3 decreased by 14% at 10 °C when increasing the concentration from 2 wht % to 6 wht %, and a maximum decrease of approximately 62% was observed with 8 wht % particle loading at all temperatures. Conversely, the specific heat capacity of EFBC with TiO2 increased by approximately 10% at 10 °C when increasing particle loading from 2 wht % to 8 wht %. The highest increment of 13% in specific heat capacity for EFBC was observed at 20 °C and 40 °C. These findings provide valuable insights for potential applications of EFBC in thermal management and other fields. [ABSTRACT FROM AUTHOR]

Particle behavior plays a crucial role in flash smelting furnaces, but limited understanding is hindering further development of this modern pyrometallurgical process. This study presents a two-way coupled CFD–DEM approach to investigate particle distribution, collision, and segregation behaviors within a furnace. The simulation results are validated against experimental data, demonstrating good agreement. The effects of the particle mass–flow rate and size distribution are then analyzed. The results indicate that small particles are carried by airflows to the center of the particle-dense region, whereas large particles remain at the outer part, worsening segregation. Increasing the mass–flow rate significantly increases the particle number density and number of particle collisions but barely influences size-induced segregation. In contrast, enlarging the size of fed particles reduces particle number density and broadens dense distribution within a safe range. This ensures the necessary space and high mixing index of the particles, which benefits high-rate smelting processes. [Display omitted] • The CFD-DEM modeling of air-particle behaviors in FSFs is established. • Distribution characteristics of different-sized particles are revealed. • Increasing the mass-flow rate results in a higher particle concentration. • Increasing the particle size reduces the dense distribution and expands it safely. [ABSTRACT FROM AUTHOR]

Much confusion has been generated in the safety assessment of food-grade TiO2 (E171) by the comingling of studies conducted on submicron-sized particles with those examining the toxicity of more minuscule counterparts. As E171 displays a nano-sized tail in its particle distribution (up to 36 % of particles with a diameter < 100 nm), it was thought that potential hazards of this food additive can be extrapolated from studies on thoroughly nanoscale formulations. This simplistic procedure may, however, overestimate the effects of the nano-sized tail of E171 because TiO2 particles readily aggregate or agglomerate in aqueous suspensions and biological matrices. The resulting larger clusters display a reduced oral bioavailability in comparison to the same material in nano-sized dimensions. Also, even if taken up in trace amounts, the smaller particles likely remain appended to larger particles or clusters and these aggregates or conglomerates may nullify to a great extent their “nano” characteristics. The purpose of this review is, therefore, to reevaluate the literature on the toxicity of TiO2 particles focusing on studies that are directly relevant for the assessment of E171. The purpose is not to avert a ban on the use of E171 in food, which might well be justified in light of the uncertainties associated with this additive employed solely for its colorant properties. Instead, it will be important to avoid in the future this same bias towards a fictional “nano” hazard, especially when evaluating more innovative engineered particles that confer true benefits for example by enhancing nutritional properties, quality, freshness, traceability or sustainability of food.

Much confusion has been generated in the safety assessment of food-grade TiO2 (E171) by the comingling of studies conducted on submicron-sized particles with those examining the toxicity of more minuscule counterparts. As E171 displays a nano-sized tail in its particle distribution (up to 36 % of particles with a diameter < 100 nm), it was thought that potential hazards of this food additive can be extrapolated from studies on thoroughly nanoscale formulations. This simplistic procedure may, however, overestimate the effects of the nano-sized tail of E171 because TiO2 particles readily aggregate or agglomerate in aqueous suspensions and biological matrices. The resulting larger clusters display a reduced oral bioavailability in comparison to the same material in nano-sized dimensions. Also, even if taken up in trace amounts, the smaller particles likely remain appended to larger particles or clusters and these aggregates or conglomerates may nullify to a great extent their "nano" characteristics. The purpose of this review is, therefore, to reevaluate the literature on the toxicity of TiO2 particles focusing on studies that are directly relevant for the assessment of E171. The purpose is not to avert a ban on the use of E171 in food, which might well be justified in light of the uncertainties associated with this additive employed solely for its colorant properties. Instead, it will be important to avoid in the future this same bias towards a fictional "nano" hazard, especially when evaluating more innovative engineered particles that confer true benefits for example by enhancing nutritional properties, quality, freshness, traceability or sustainability of food. [ABSTRACT FROM AUTHOR]

Coal is the dominant energy resource in China. With the Chinese policy of committing to reducing peak carbon dioxide emissions and achieving carbon neutrality, coal separation has recently become a hot topic, especially the fluidized separation of fine particles. In this study, micron-sized particles were introduced to ameliorate the properties of the traditional fluidized bed. The expansion characteristics of the micron-sized-particle-dense medium were explored. A bed expansion prediction model of the micron-sized-particle-dense medium was established, and the prediction error was about 10%, providing a theoretical basis for understanding the distribution characteristics of the bed. This model also helped predict the bed density in the presence of a micron-sized-particle-dense medium, and the prediction accuracy was between 85% and 92%, providing a theoretical basis for selecting and popularizing fluidized beds for industrial separation. [ABSTRACT FROM AUTHOR]

Abstract: In this work, ethylenediamine tetraacetic acid disodium (EDTA·2Na) is used as a complexing agent to control the preparation of micron‐sized barium sulfate spheres via a precipitation reaction between sodium sulfate and barium chloride at 35 °C. To better characterize the morphology, structure and particle size of barium sulfate spheres and to understand the formation mechanisms, X‐ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), laser particle size analyser (PSD) and scanning electron microscopy (SEM) are employed. The influence of the reaction conditions such as pH, [EDTA/Ba2+] ratio, [Ba2+] concentration and reaction time are investigated. These parameters affected the size and morphology of barium sulfate. Moreover, this work attempts to provide a primary understanding of the formation mechanism of micron‐sized spherical barium sulfate spheres [ABSTRACT FROM AUTHOR]

The average iron content of iron ore is < 30%; therefore, crushing, grinding, milling and other processing techniques must be executed before smelting. Currently, it is expensive to break iron ores using mechanical grinding. Experiments have been carried out to develop a novel approach of producing iron ore powder. First, the iron ore is placed in a high-pressure chamber, and then liquid CO 2 is injected into the chamber. Second, considering energy recycling, after the iron ore pores are filled with liquid CO 2 , dissociative liquid CO 2 is substituted and collected for cyclic utilization. Third, an initial high pressure is applied inside the chamber using a water pump in order to increase the energy input. Fourth, the pressure is rapidly unloaded. After penetration and gasification expansion, the iron ore will immediately be converted into micron-sized particles. Laser grain size analysis indicated that the grain size of the iron ore particles ranges between 30 and 50 μm, which will satisfy the requirements of gravity separation, magnetic separation and the flotation process. This is a highly efficient and low-cost method that has excellent industrial promotion value. [ABSTRACT FROM AUTHOR]

An effect of shielding of an intense solar radiation towards a solar probe with the use of micron-sized SiC particles generated during ablation of a composite thermal protection material is estimated on a basis of numerical solution to a combined radiative and heat transfer problem. The radiative properties of particles are calculated using the Mie theory, and the spectral two-flux model is employed in radiative transfer calculations for non-uniform particle clouds. A computational model for generation and evolution of the cloud is based on a conjugated heat transfer problem taking into account heating and thermal destruction of the matrix of thermal protection material and sublimation of SiC particles in the generated cloud. The effect of light pressure, which is especially important for small particles, is also taken into account. The computational data for mass loss due to the particle cloud sublimation showed the low value about 1 kg/m 2 per hour at the distance between the vehicle and the Sun surface of about four radii of the Sun. This indicates that embedding of silicon carbide or other particles into a thermal protection layer and the resulting generation of a particle cloud can be considered as a promising way to improve the possibilities of space missions due to a significant decrease in the vehicle working distance from the solar photosphere. [ABSTRACT FROM AUTHOR]

The collision-adhesion and deposition of micron-sized dust particles in the internal cooling duct with pin fin arrays are investigated, integrating the energy dissipation collision model of spherical particles and gas-solid two-phase theory. The effects of particle Stokes number (Stk = 0.12, 0.48, and 3), particle temperature (T p = 1173, 1223, 1273, and 1343 K), and streamwise pin spacing (S = 2.5, 3, and 3.75 D) on the collision ratio, sticking ratio and deposition ratio of particles on pin fins and endwalls are investigated when the inlet Reynold number is 36,575. The results show that the pin collision ratio rises drastically with the increase of particle size, while the sticking ratio decreases. The particle temperature has a minimal impact on the collision ratio, sticking ratio, and deposition ratio when particle temperature is below 1273 K. However, the collision ratio of particles on the pins decreases appreciably when the particle temperature increases further up to 1343 K, while the sticking ratio increases significantly. The pin fin arrays with the streamwise spacing of 3 D and 3.75 D reduce the number of endwall deposition of particles with Stokes number of 0.12, compared to the pin fin array with a streamwise spacing of 2.5 D. The windward region of the pin shows the largest potential for dust deposition and the maximum deposition height occurs at the junction of the pin-endwall. Moreover, the deposits on the pin fin grows and tends to be more uniform with the increase of particle temperature, according to the deposition profile on the pin. [ABSTRACT FROM AUTHOR]

It is observed that a diffusion-controlled mechanism applied to the burning of micron-sized particles is not applicable to the combustion of nano-sized particles burning under kinetically controlled conditions. Furthermore, when heat transfer occurs between micron-sized particles and air, Nusselt number can be assumed to be constant and equal to 2, while this number is a function of Knudsen number when heat transfer occurs between nano-sized particles and air. Ignition temperatures of micron- and nano-sized particles are also different. In this article, mass and energy conservation equations for both particle and gas phases are solved. By doing so, flame velocity is obtained. Afterwards, with respect to different combustion characteristics of micron-and nano-sized particles such as ignition temperature, burning time, and Nusselt number, the effect of particle size on the flame velocity of aluminum particles combustion in air is studied and compared with experimental and numerical results. At the equivalence ratio of 0.85, it is shown that flame velocity is proportional to d−0.94 and d−0.56 for micron- and nano-sized aluminum particles, respectively. [ABSTRACT FROM PUBLISHER]

Purpose: In this study, micron-sized crystalline drug particles of irbesartan (IBS) were prepared to improve its stability and dissolution rate. Method: The approach to crystalline particles was based on the liquid precipitation process by which the amorphous particles were prepared. Pharmaceutical acceptable additives were used as the crystallization agent to convert the amorphous drug into crystalline particles. High pressure homogenization (HPH) process has been employed to reduce the size of the crystalline particles, and the micron-sized particles were obtained by the freeze-drying process. Results: Different additives show different influences on the polymorphic form of IBS. Polyvinylpyrrolidone (PVP) and hydroxypropyl methylcellulose (HPMC) were effective in stabilizing amorphous particles instead of converting amorphous drug into crystalline particles, while poloxamer407 (F127) and tween80 (T80) could convert the amorphous drug into crystalline particles. T80 was also effective in controlling the particle size than that of F127. After HPH, crystalline particles with an average of 0.8 μm were obtained. The freeze-dried micron-sized crystalline particles exhibited significantly enhanced in vitro dissolution rate when compared to the raw drug. SEM, FT-IR, XRD, DSC and dissolution rate studies indicated that the micron-sized particles were stable during 6 months storage. Conclusion: The preparation of micron-sized crystalline drug particles is an effective way to improve the stability and dissolution rate of irbesartan. [ABSTRACT FROM AUTHOR]

Abstract: Electrical resistance tomography (ERT) was employed to study the solid–liquid mixing in a slurry reactor equipped with a top-entering axial-flow impeller. The ERT data were used to reconstruct the tomogram using the linear back projection algorithm and calculate the degree of homogeneity. In this study, the effects of the impeller speed (252–400rpm), impeller pumping mode (downward and upward), impeller type (A310, A100, A200, A320, A315, 3AM), impeller off-bottom clearance (T/3.8–T/2.5, where T is the tank diameter), impeller diameter to tank diameter ratio (D/T =0.29–0.47), particle size (5.2–9.1μm), and solids concentration (15–30wt%) on the degree of homogeneity of micron sized latex particles in a slurry reactor were explored. The results showed that the level of homogeneity in a solid–liquid mixing system improved with the increase in impeller speed. However, after achieving the maximum level of homogeneity, any further rise in the impeller speed had a detrimental effect on the level of homogeneity. A310 impeller, with D/T ratio of 0.31, demonstrated the highest level of homogeneity while the upward pumping direction was found to be more efficient than the downward one. In addition, a clearance of T/3 proved to create the highest level of homogeneity. The results also showed that a rise in the size and concentration of particles decreased the level of homogeneity. Thus, 5.2μm latex particles with the concentration of 15wt% demonstrated the highest level of homogeneity. [Copyright &y& Elsevier]

Abstract: Micrometre-sized particles of Sn/SnSb were produced with a simple technique consisting in melting commercial ingots of tin and antimony separately at 280°C and 680°C, respectively, and casting them together in a ceramic boat. The solid alloy was then crushed into a homogeneous powder by grinding and sieving. The obtained powder was characterised by X-ray diffraction, and electron microscopy. Elemental and phase composition analyses were performed via, inductive coupled plasma and differential scanning calorimetry, respectively. The material was further tested as electrode material in a lithium galvanic cell. It showed relatively good capacity retention for at least 15 cycles. TEM analysis on post-mortem electrode samples showed the formation of nanostructures after the first discharge followed by a progressive disappearance of the micron-sized particles upon further cycling. Fading at higher cycles is explained by the formation of isolated metallic nano-particles that become inactive for further storage of lithium. [Copyright &y& Elsevier]

• A radiative cooler with thermal insulation ability has been proposed. • This radiative cooler contains different sized particles. • This cooler achieved cooling water to ~8.6 °C below ambient air temperature in temperature rising period. Passive radiative cooling can extract heat energy from an object to the cold sky. When using the cold object to cool other object, such as water, it's critical to reduce the coldness loss, and thermal insulation provides an efficient solution. Here, a silica radiative cooler with thermal insulation ability was prepared to cool water. This cooler can prevent sunlight transmission by scattering sunlight back to the environment, while reduce temperature via emitting heat radiation to the cold sky, thermal conduction from the top surface to the water can also be suppressed due to the high thermal resistance. Using this cooler, we have achieved cooling water to ~6.9 °C below the ambient air temperature. Our study indicates the application potential for the silica cooler and proposes a new idea for energy saving in air conditioning system. [ABSTRACT FROM AUTHOR]