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The Mu Us Sandy Land is a region characterized by wind-blown sand and soil erosion in northern China. To enhance the soil quality of this area, various organic materials were incorporated into the mixed soil at a volume ratio of 1:2 for feldspathic sandstone to sand. Culture was conducted in the field and under constant temperature conditions in laboratory culture chambers. Four treatments were established in the experiment, each calculated based on weight ratio and controlled (with no organic material added, CK); single application of straw (5% straw, P1); single application of biochar (5% biochar, P2); combined application of biochar and straw (5% biochar + 5% straw, P3). After 90 days of culture, soil samples were collected for analysis of various indicators such as soil aggregate particle size distribution, water stability of soil aggregates, mean weight diameter, mean geometric diameter, and fractal dimension using dry sieving and wet sieving methods. The objective is to establish a scientific basis and provide technical support for addressing the challenges associated with compound soil and implementing rational fertilization measures. The research results indicate that: (1) The quantity of aggregates > 0.25 mm under different treatments follows the order CK < P1 < P2 < P3, and the differences between treatments are significant (P < 0.05); (2) Soil water stability, mean weight diameter (MWD), mean geometric diameter (GMD), and fractal dimension of soil aggregates in compound soil with different organic material additions are superior to the control, and the effect of biochar on improving soil aggregates is better than that of corn straw. The combined application of both significantly improves the effect compared to single applications. In both culture modes, under wet sieving, the P3 treatment shows the highest MWD and GMD of soil aggregates, with an increase ranging from 3.45% to 85% and 4.55% to 38.46%, respectively, compared to other treatments. (3) The trend of fractal dimension among treatments is consistent: P3 < P2 < P1 < CK, and the differences between treatments are significant (P < 0.05). Moreover, there is a good negative correlation linear equation relationship between the fractal dimension (y) and WR > 0.25 (x) of compound soil, with a correlation coefficient of up to 0.9851. In conclusion, the incorporation of organic materials can effectively enhance the proportion of macroaggregates in compound soil consisting of Feldspathic sandstone and sand, thereby improving soil stability and erosion resistance. The optimal outcome is achieved through the combined application of biochar and straw. Indoor culture proves to be more effective than field culture, while wet sieving accurately reflects the structural characteristics of compound soil under both dry and wet sieving treatments. [ABSTRACT FROM AUTHOR]

In the article, the general properties of copper nanoparticles, their requirements, recommendations for use, and methods of production are presented. In recent times, since copper nanoparticles are increasingly being used in electronics, as catalysts, as coatings on metal surfaces, and to aid in the medical field, the demand for copper nanoparticles may increase dramatically soon. After analyzing the existing technologies, experiments were carried out using the method of chemical precipitation with the help of iron as an environmentally and economically effective technology. In the experiments, surfactants used for protection against oxidation, experimental temperature, concentration and optimal parameters were determined. The results of the analysis of several XRF spectra, SEM scanning electron microscope, IR-Fourier spectrometer, UV diffusion reflection spectroscopy of raw materials and obtained samples are presented. Based on the experiment, the conditions for obtaining the results of 98.3% pure copper particles with a fineness of 170 nm are explained. [ABSTRACT FROM AUTHOR]

Extraction of molybdenum (Mo) from jordisite is difficult due to the amorphous state of MoS2. In this study, mechanical activation was employed to pretreat this type of ore with a low Mo content of 0.26%, and then molybdenum and uranium were both extracted from the milled ore using sulfuric acid. The effects of milling time, oxidant, and optimal leaching conditions were investigated in the laboratory. The results show that the mechanical activation will reduce the particle size and increase the specific surface area of the ore under certain milling conditions. Mechanical activation without oxidants in a hypoxia environment is not conductive to the recovery of molybdenum. When the oxidant of MnO2 is added during the milling process, the Mo recovery will increase greatly. The effect of mechanical activation on U recovery is not so obvious. The phenomenon of agglomerate will occur during the milling process, which will reduce Mo recovery seriously, especially when the milling time is more than 120 min. The Mo and U recovery can reach 84.52% and 61.39%, respectively, after optimization of sulfuric acid leaching process conditions. [ABSTRACT FROM AUTHOR]

To study the composition and migration of agglomerate in reclaimed asphalt pavement (RAP), two different RAPs were selected, and the aging performance of RAPs was evaluated. Then, the RAPs were sieved into a single particle size from 13.2 to 0.075 mm, and hot-mix and extraction tests were carried out on the RAPs with single particle sizes. Through the comparative analysis of gradations of the hot mixing and extraction of RAPs with single particle sizes, the composition and its migration rule of agglomerates of RAPs were analyzed. The thickness of gradation (TG), thickness of gradation ratio (TGR), degree of separation (DS), and degree of separation ratio (DSR) were proposed to evaluate the fragmentation characteristics of RAP agglomerates with single particle sizes. According to the DS index, the grading standard of RAP agglomerates was determined. The results show that the agglomerate of RAP at each particle size is mainly composed of the mineral aggregate of the initial particle size of RAP, the aggregate with one gradation lower than the initial particle size, and other aggregates with smaller and finer content. During the hot mixing, the RAP with the single particle size larger than 2.36 mm mainly undergoes old agglomerate fragmentation, whereas RAP with the single particle size ≤2.36 mm will not only break into small particles, but also integrate new agglomerates. The RAP agglomerates can be divided into strongly bound agglomerates and weakly bound agglomerates according to whether they will be broken and separated during hot mixing. With the decrease of particle size of RAP, the proportion of strongly bound agglomerates gradually rises, whereas the proportion of weakly bound agglomerates declines. [ABSTRACT FROM AUTHOR]

Molten salt-based nanofluid is a thermal storage and heat transfer medium for concentrated solar thermal power plants formed by adding nanoparticles to molten salt, which can enhance the thermal performance of molten salt. However, the nanoparticles tend to aggregate in nanofluids, causing changes in thermal properties. In this work, molecular dynamics simulations were used to study the effect of morphological characteristics of aggregates on the thermal conductivity and specific heat capacity of molten salt-based nanofluids. The results show that the aggregated nanoparticles cause a greater increase in thermal conductivity and specific heat capacity than dispersed nanoparticles. Additionally, the increase in fractal dimension leads to thermal conductivity reduction, while there is no clear correlation between the fractal dimension and specific heat capacity. New insights into the thermal properties of aggregated nanofluids are provided by analyzing the contribution of material components, heat flux fluctuation modes, and energy compositions. It is found that the thermal conductivity of aggregated nanofluids is mainly dominated by the base liquid and collision term. However, the specific heat is not related to the variation in the contribution of different energy compositions. Moreover, compared to the dispersed nanofluid, the increased specific heat capacity of aggregated nanofluids is attributed to the thicker semi-solid layer. This study provides guidance for the design and control of the thermal properties of molten salt-based nanofluids. [ABSTRACT FROM AUTHOR]

Carbon nanomaterials are unique with excellent functionality and diverse structures. However, agglomerated structures are commonly formed because of small‐size effects and surface effects. Their hierarchical assembly into micro particles enables carbon nanomaterials to break the boundaries of classical Geldart particle classification before stable fluidization under gas‐solid interactions. Currently, there are few systematic reports regarding the structural evolution and fluidization mechanism of carbon nano agglomerations. Based on existing research on carbon nanomaterials, this article reviews the fluidized structure control and fluidization principles of prototypical carbon nanotubes (CNTs) as well as their nanocomposites. The controlled agglomerate fluidization technology leads to the successful mass production of agglomerated and aligned CNTs. In addition, the self‐similar agglomeration of individual ultralong CNTs and nanocomposites with silicon as model systems further exemplify the important role of surface structure and particle‐fluid interactions. These emerging nano agglomerations have endowed classical fluidization technology with more innovations in advanced applications like energy storage, biomedical, and electronics. This review aims to provide insights into the connections between fluidization and carbon nanomaterials by highlighting their hierarchical structural evolution and the principle of agglomerated fluidization, expecting to showcase the vitality and connotation of fluidization science and technology in the new era. [ABSTRACT FROM AUTHOR]

A method for the determination of Fetot, SiO2, P, V2O5, TiO2, Cr2O3, Ni, Cu, and Zn in iron ore raw materials (i.e., pellets, iron ore agglomerate, aspiration dust and slag component of scrap) by the method of atomic emission spectrometry with inductively coupled plasma (ICP-AES) has been developed using microwave sample preparation in analytical autoclaves. The composition of the acid mixture for the complete dissolution of the sample component was proposed, and the parameters of microwave decomposition, excluding the depressurization of the autoclave and the loss of sample elements which form volatile compounds, were selected. The developed method of microwave sample preparation in closed autoclaves made it possible to decompose iron ore samples using the minimum amount of acid (17 cm3) in 45 min. Conditions for the determination of normalized elements in iron ore samples by the ICP-AES method after microwave sample preparation were determined: the operating parameters of the spectrometer were optimized, the analytical lines of each determined element free from spectral overlaps were selected, and the efficiency of using cadmium as an internal standard was experimentally proved. The equations for calibration dependences and the ranges of determinable contents are presented. When using cadmium as an internal standard in the analysis of iron ore, a decrease in the value of the standard deviation from 0.17 to 0.04 is observed when determining Cr2O3; from 0.02 to 0.004 when determining Fe; from 0.03 to 0.002 when determining SiO2; from 0.015 to 0.008 when determining TiO2; and from 0.17 to 0.02 when determining V2O5. The correctness of the determination of the standardized elements by the developed method is evaluated using certified reference samples (CRS) similar in composition to the analyzed material. The results of determining the standardized elements according to the developed methodology were compared with the data obtained using GOST-approved methods of analysis and then checked in accordance with the recommendations of RMG 76-2014. The developed ICP-AES technique is characterized by a wider linear range of the determined concentrations than that in GOST-approved techniques, thus providing determination of the components in iron ore raw materials that could not be controlled before. [ABSTRACT FROM AUTHOR]

The research aims to develop a novel and safer milling route to produce Hard Metals. Considering the risks associated with milling fine particles under organic solvents, especially the increased fire and explosion risks, we propose milling under aqueous milling media to diminish the risks associated with fire hazards, while maintaining the oxidation level at a minimum. The samples were sintered in an industrial sintering oven under vacuum at 1380°C subsequent to milling and drying. The characterisation of the materials has been done by X-ray diffraction, scanning electron microscopy, particle size analysis, optical microscopy, and a magnetometer. The obtained results indicate that appropriate properties of the powders after milling and drying as well as the desired biphasic (Co-WC) phases were obtained after sintering, thus proving the feasibility of such a route and diminishing specific fire hazards. [ABSTRACT FROM AUTHOR]

Burning of a high-energy pasty propellant aimed at creating engines with a burning end surface is studied. Specific features determining the burning rate, characteristics of the agglomeration process, and surface layer properties are determined. It is shown that these features are similar to those observed for solid propellants based on an active binder with a linear polymer. Possible aspects of improvement of propellants of this type are determined. [ABSTRACT FROM AUTHOR]

The addition of aluminum particles in composite propellants has a positive effect on the performance of solid rocket motor, while it also brings some changes in the ignition behaviors. To clarify the ignition process and performance of aluminized propellants, a visualization experimental system was built. It is found that the ignition process of aluminized propellants mainly includes heating and melting of the solid phase, evaporation, mixing and ignition of decomposed gas. Besides, few aluminum particles agglomerate together and they are not ignited during the ignition process of propellants. According to the process of ignition, the ignition delay time can be described as the sum of pyrolysis time, mixing time and chemical reaction time. After the propellants is ignited and the stable flame is formed, the aluminum particles on the burning surface mainly undergo exposure – accumulation – fusion – separation – ignition – combustion. And the structure of the agglomerate transitions from a coral-like to an oxidized cap. At the same time, the ignition of agglomerated products occurs in the stable flame. With the increase of aluminum content and initial aluminum particle size, the ignition delay time also increases, but the proportion of these three times in the ignition delay is not very much related to the formulation of propellants. With the increase of power density of ignition, the ignition delay time decreased markedly, but the decreasing trends continuously became more gradual and eventually flattened out. As the power density of ignition increases, the percentage of pyrolysis time in the ignition delay time decreases rapidly and gradually stabilizes, while the percentage of mixing time gradually increases and the chemical reaction time does not change much. A sufficiently large and reasonable ignition energy power can reduce the ignition delay time and also reduce the impact of the differences between formulations on ignition performance. • The full ignition process of composite propellants with aluminum particles was revealed. • The ignition moment of aluminum particles during the combustion of propellants was analyzed. • The effect of aluminum particle characteristics on the ignition delay time and each fraction time was studied. [ABSTRACT FROM AUTHOR]

The uniaxial die compaction and sintering is an important industrial production method for metal and ceramic components. While submicron- and nano-sized powders are finding increasing use for making dense materials with finest grain sizes, the uniformity of microstructure, and then, the reliability of the products depend on the heterogeneity in powder packing structure. Here we applied the synchrotron X-ray multiscale-CT to characterize the complex domain structures, i.e., agglomerates, in powder compacts, and revealed how heterogeneous distribution of fine residual pores is formed by the differential sintering of agglomerates by using a submicron alumina powder as a model. A crack-like defect was identified as the largest defect. This defect was formed along the boundary between a plate-shaped agglomerate and its surroundings. A technique was also proposed to visualize the heterogeneous distribution of residual pores by using SEM. These characterization methods will open up new possibilities for the optimization of ceramic processing. [ABSTRACT FROM AUTHOR]

Wet agglomerates such as iron-ores, tablets, and aggregates are omnipresent in multi–field industries. However, our understanding of the impact dynamics of these materials is limited. Recently, Vo et al. reported the mechanical strength and deposition height of impact agglomerates which are well described by the Capillary–Stokes inertial number by considering the physical assumption of the irreversible breakage of capillary bonds between particles in the pendular regime (Vo et al. in Comput Particle Mech). Here, we provide a comprehensive comparison of the roles of the reversible and irreversible characteristics of capillary bridges on the agglomerate strength, deposition behavior, and energy consumption of agglomerates impacting a rigid surface. We reveal that the roles of both characteristics of capillary bonds strongly expressed via the differences of the mechanical strength, deposition behavior, and energy absorption of wet agglomerates. In particular, the mechanical strength of agglomerates of the reversible case is slightly higher than that of the irreversible one due to having small agglomerates' deformation and the small number of loosing capillary bonds, and the larger differences of the final–deposition height and energy consumption of such agglomerates between the reversible and irreversible cases are due to the formation/reformation of capillary bonds and dry interactions. Interestingly, by systematically varying a broad range of values of controlled parameters such as the liquid viscosity, the liquid–vapor surface tension, and the impact speed of such agglomerates, the strength, deposition height, and energy consumption for both reversible and irreversible cases nicely collapse on concave master curves with the same function forms of the cohesive inertial number. The function form of the agglomerate strength represents a non–general(ized) μ (I) rheology due to the strong domination of the cohesive stress as compared to gravity (or confining stress). These results provide evidence of important applications for the handling of cohesive granular materials in industries. [ABSTRACT FROM AUTHOR]

The main goal of this paper is to propose a method for the 3D morphological characterization of compact aggregates using 2D image analysis. The problem at hand is, for example, the 3D morphometric characterization of latex nanoparticle aggregates. The only available information is 2D opaque projection images of these aggregates, one projection per aggregate. In this context, a method to estimate the 3D morphological characteristics of an aggregate such as the Volume, Surface Area or Solidity from a single opaque projection is proposed. This method is based on a stochastic geometric model called GRAPE (Geometrical Random Aggregation of Particles Emulation) and requires some strong assumptions, and in particular prior estimation of the volume. The model is based on an iterative packing of spheres of identical radii. For each iteration, a fitting function allows to reach objectives corresponding to the desired 2D properties (Area, Perimeter, Aspect Ratio, ...). In order to implement the method, an optimization process must be performed on two parameters of the model: the radius of the primary particles r and an overlapping distance di. As a validation, this process will be applied to synthetic aggregates, themselves generated from the GRAPE model, then to a population of 104 synthetic aggregates, and finally to 3D printed aggregates whose 3D morphological properties are known thanks to an STL file, and whose projected images have been produced using a morphogranulometer. The results obtained show an excellent approximation of 2D properties by the GRAPE model, and very good results for 3D properties, with less than 5% error on average and less than 2% error in most cases. [ABSTRACT FROM AUTHOR]

Changing the physical state from crystalline to amorphous is an elegant method to increase the bioavailability of poorly soluble new chemical entity (NCE) drug candidates. Subsequently, we report findings from repeat-dose toxicity studies of an NCE formulated as a spray-dried amorphous solid dispersion (SD-ASD) based on hydroxypropyl methylcellulose acetate succinate (HPMC-AS) in rats. At necropsy, agglomerates of SD-ASD were found in the stomach and small intestine, which in reference to literature were termed pharmacobezoars. We interpreted the pH-dependent insolubility of HPMC-AS in the acidic gastric environment to be a precondition for pharmacobezoar formation. Gastric pharmacobezoars were not associated with clinical signs or alterations of clinical pathology parameters. Pharmacobezoar-correlated histopathological findings were limited to the stomach and consisted of atrophy, erosion, ulcer, and inflammation, predominantly of the nonglandular mucosa. Pharmacobezoars in the small intestines induced obstructive ileus with overt clinical signs which required unscheduled euthanasia, prominent alterations of clinical pathology parameters indicative of hypotonic dehydration, degenerative and inflammatory processes in the gastrointestinal tract, and secondary renal findings. The incidence of pharmacobezoars increased with dose and duration of dosing. Besides the relevance of pharmacobezoars to animal welfare, they limit the non-observed adverse effect level in nonclinical testing programs and conclusively their informative value. [ABSTRACT FROM AUTHOR]

The influence of the energy of thermal plasma on the morphology and phase composition of agglomerated refractory oxide powders was investigated. It was established that on processing agglomerated powder, based on the ash residue from a state district power plant, in the flow of thermal plasma with different thermophysical characteristics of the carrier medium, three types of morphological features of the particles are formed: dense particle with separate gas inclusions in the surface layer; hollow spherical particle; vitrified agglomerated particle with solid-phase inclusions. According to XRD data, after processing, agglomerated polycrystalline powders are amorphous. On the x-ray diffraction patterns of particles processed in the turbulent regime of plasma jet outflow, there is a small Bragg peak of β-quartz. This means that the grains do not reach the molten state at the center of the agglomerate. [ABSTRACT FROM AUTHOR]

Electrets were prepared by spin‐coating the dispersion of fine silica powders, and their charge retention characteristics were investigated. Finer silica aggregates were formed on the PTFE surface layer by spin‐coating the dispersed solution of fine silica powder than those formed by spray‐coating colloidal silica. Electrets using fine silica powder also showed better charge retention characteristics than those using colloidal silica. Such an improvement in the charge retention might be due to the suppression of discharge in the excessive gap caused by coarse silica aggregates. Then, ECSs were fabricated using the prepared electrets, and their transmitting and receiving characteristics of airborne ultrasound were also investigated. The peak sensitivity of the ECS using a spin coating of fine powdered silica dispersion was slightly improved from those using spray coating of colloidal silica. On the other hand, the peak frequency and frequency band were greatly improved using spin coating of fine powdered silica dispersion. Therefore, ECS using fine silica powder is expected to be applied as a broadband airborne ultrasonic sensor. [ABSTRACT FROM AUTHOR]

Burning of high-energy condensed systems may include the formation of an intermediate structure (skeleton layer, which significantly affects the burning process). The influence of binder curing on the formation of such a structure is studied experimentally. It is demonstrated that the laws of the skeleton layer formation during binder curing depend to a large extent on the polymer structure. A specific role of the substance acting as a binder is determined. The basic features of modeling phenomena in the surface layer with and without the skeleton layer are presented. The possibility of predicting a number of characteristics of the burning process is demonstrated. [ABSTRACT FROM AUTHOR]

Attrition and breakage of agglomerates are prevalent during production and handling processes in many industries. Therefore, it is highly desirable to be able to model and analyse the agglomerate breakage process under various loading conditions. The ensemble strength and breakage patterns of agglomerates are still not well understood despite a significant amount of research being carried out. In this study, three-dimensional discrete element method (DEM) simulation of the impact breakage behaviour of agglomerates were performed using a Timoshenko beam bond model which considers axial, shear, twisting and bending behaviours on the bonds. An advantage of the Timoshenko beam bond model is the pertinent parameters of the bond contact have clear physical meaning and therefore could be determined through corresponding experimental characterisations. The mechanical properties of the bonds in this study were firstly calibrated using experimental measurements. The validation of the Timoshenko beam bond model was then undertaken by direct comparisons between the numerical simulation and experimental results of impact tests. It was shown that the time evolution of the agglomerate breakage process obtained from simulation had good agreement with experimental observations. Numerical results indicate that most of the damage happens at the early stage of the impact and a cone shape fracture zone is formed quickly inside the agglomerate where strong compressive stresses are concentrated. It is found that the exterior of the fracture zone is surrounded by an arch shape tensile stress which dominates the fracture propagation. [ABSTRACT FROM AUTHOR]

• Simulation of a 3D, isothermal model of ion-pair HT PEMFC is implemented in COMSOL. • Agglomerate sub-model of cathode catalyst precisely assesses catalyst loading impact. • Performance is depicted by polarization curves, gas concentrations and overpotential breakdown. • Experimental validation for both non-protonated and protonated FC is carried out. • Graded catalyst layer design is proposed to improve FC performance. A steady-state, isothermal simulation of a 3D high temperature (HT) ion-pair proton exchange membrane fuel cell (PEMFC) model, utilizing a quaternary ammonium biphosphate ion-pair membrane, was conducted in COMSOL Multiphysics for the first time. The performance of the fuel cell was analyzed, in terms of polarization curves, molar gas concentrations, and overpotential breakdown to determine mechanism resulting in loss. Experimental validation was performed for both non-protonated and protonated ion-pair fuel cells. The homogeneous catalyst layer model overestimated the performance at low catalyst loading by up to 32%. Hence, this study utilized an agglomerate sub-model of the cathode catalyst layer, to accurately capture the effect of catalyst loading on fuel cell performance. Additionally, a graded catalyst layer design was proposed to improve the catalyst utilization leading to high fuel cell performance. It was found that a graded catalyst layer with higher loading facing the membrane side improved the performance by 5.5% over uniformly loaded catalyst layer. Furthermore, the influence of operating conditions like temperature and back pressure is highlighted. Overall, this study offers a comprehensive approach to understanding HT ion-pair PEMFC operation and optimizing the catalyst structure. [ABSTRACT FROM AUTHOR]

[Display omitted] • Particle agglomerate behavior under electric field is quantitatively analyzed. • Agglomerate' 3D twist visualization was realized under flow-electric field. • Action mechanism of dipole moment on particle agglomerate was further developed. The research developed a new mechanism for particle agglomeration growth and fracture in the flow-electric coupling field. Microscopic visualization experiments reveal an optimum voltage range for controlling agglomerate growth dynamics. Additionally, we observed, for the first time, twisting behaviors of particle agglomerates during the growth and fracture process under the influence of the flow-electric field. A correlation between twist and fracture, varying with the increase in applied voltage, was identified. Moreover, we identified two distinct agglomeration modes: dendritic and chain agglomerates, each exhibiting unique growth characteristics. We discovered that the growth, twisting, and fracture of inclined dendritic agglomerates are influenced by two components of the electric dipole moment: the axial (P g) and radial (P t) components, with the aid of numerical simulation. Chain-like agglomerates exhibit growth followed by fracture. Our findings offer insights into the controlled growth of submicron particle agglomerates in gas phases using electric fields. [ABSTRACT FROM AUTHOR]

Measuring the 3D morphological properties of granular objects such as aggregates is a critical issue in many fields of science and industry, especially when the objects are fragile or hard to sample. For these reasons, non-invasive techniques based on image analysis are being developed. However, most image analysis techniques can only measure 2D properties. This paper presents a new approach based on both image analysis and a 3D stochastic geometric model called VOX-STORM (VOXel-based STOchastic geometRical Model) to estimate 3D morphological properties. By adjusting the parameters of the model, the latter is able to generate populations of objects whose 2D property distributions match those measured by image analysis, and to predict 3D morphological property distributions. The model is based on a dual architecture combining voxelized structure and alpha-shape meshing of the external surface, which makes object generation extremely fast (about 1000 objects in 20 s), while allowing rapid computation of 3D characteristics. The method is validated twice, first on 3D printed aggregates and then on a population of 40,000 synthetic aggregates, with mean errors of less than 2.5% in all cases and less than 1% for 2D properties. It is then applied to two sets of images of latex aggregates captured by a morphogranulometer. The morphological property distributions and fractal dimensions are compared to ground truth in the 2D case and to laser diffraction measurements in the 3D case. The results are also compared with two other recent stochastic geometric models, and the VOX-STORM model outperforms them in all scenarios, as well as in speed of execution, while agreeing with experimental measurements. Finally, directions for future work are suggested. [Display omitted] • VOX-STORM combines voxel structure and alpha-shape meshing. • Generates 1000 objects in <20 s with full morphological control. • Validated with 3D prints and 40,000 synthetic objects. • Estimates 3D properties from 2D image measurements. • Predictions validated with latex aggregate measurements. [ABSTRACT FROM AUTHOR]

[Display omitted] • The adhesion mechanism of powders is obtained in fluidized bed. • The sticking and rebound behaviors of aggregates are explored. • Critical sticking velocity decreased with the oblique angle of aggregates. • Higher energy dissipation can be obtained in z -direction oblique collision. • The energy loss rate is the decisive factor for powder adhesion. In this study, the effects of impact parameters and multi-particle agglomerates on the restitution coefficient , critical sticking velocity, energy dissipation and adhesion rate were investigated comprehensively. Firstly, by comparing the various forces that may affect powder adhesion, the adhesion mechanism between powders and bed particles in high-temperature fluidized bed is determined. Then the sticking and rebound behaviors are discussed. For single powder, the restitution coefficient can be divided into a rolling region and a rebounding region when impacting an inclined wall. But Poisson's ratio and Young's modulus have a weak effect on the restitution coefficient. For multi-particle agglomerates, the impacting behaviors are more complex, including normal collision, tangential collision, spin motion and rolling, which increase the adhesion rate. With the increase of the oblique angle or agglomerated particles, the viscoelastic loss is increased, but the restitution coefficient and critical sticking velocity are reduced. Compared to x -direction oblique collision, viscous loss is larger at z -direction oblique collision, approximately 10 % more at four-particle agglomerates, which promotes the impacting adhesion. More interestingly, the energy dissipation rate is the largest in three-particle agglomerates and the adhesion rate increases by 50 % when the agglomerated particle number changes from 2 to 3. [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. [ABSTRACT FROM AUTHOR]

Combining laser ignition tests with quenched particle cross-sectional analyses, this study explores the formation of bubbles and microexplosions in burning boron agglomerates, and discusses the plausible mechanisms behind the microexplosion (expansion–rupture) phenomenon. High-resolution images reveal that these phenomena are caused by bubble nucleation and growth within the molten droplet. Based on the timescale, it is categorized into weak expansion and strong expansion phenomena. The expansion rate of droplets during the weak expansion process mostly ranges between 0.006 m/s and 0.4 m/s, while during the strong expansion process, it predominantly falls between 0.4 m/s and 1 m/s. An increase in ambient pressure results in the delayed occurrence and reduced frequency of the expansion–rupture phenomenon. When the ambient pressure exceeds 3 atm, the expansion phenomenon no longer occurs. In addition, a decrease in the initial diameter of the agglomerates lowers the overall occurrences of expansion–rupture. Analysis of the quenched particle cross-sections reveals that the size and density distributions of the pores within the boron agglomerates reduce gradually during the combustion process. In addition, the surface oxide layers of certain pores are removed during combustion. Estimates of the vaporization rates of (BO) n and B 2 O 3 support the speculation that the expansion of molten boron droplets is attributed to the evaporation of boron oxide layer. In this process, the molten boron acts as a heating surface to evaporate the boron oxide trapped inside the droplet, thus producing B 2 O 3 , B 2 O 2 , and BO, and leading to droplet growth and tearing of the liquid film. Analysis of bubble growth indicates that the merging of adjacent bubbles to reach the critical nucleation size is probable the starting point of the expansion process. These results can be helpful in promoting the combustion efficiency of boron within the combustion chamber. [ABSTRACT FROM AUTHOR]

The geometrical modeling of granular objects is a complex challenge that exists in many scientific fields, such as the modeling of granular materials or rocks and coarse aggregates with applications in civil, mechanical, and chemical engineering. In this paper, a model called SPHERE (Stochastic Process for Highly Effective Radial Expansion) is proposed, which is based on the deformation of an ellipsoid mesh using multiple 3D Gaussian random fields. The model is designed to be flexible (full control over 2D and 3D morphological properties of granular objects), ultra-fast (over 1000 aggregates in less than 5 s), and independent of the mesh and base shape used (as long as it is a star-shaped object). The flexibility of the model and its ability to reflect real data is illustrated using images of latex nanoparticle aggregates. Using 2D measurements on images from a morphogranulometer, a method based on the SPHERE model is proposed to estimate the 3D morphological properties of aggregates. A multiscale optimization process is applied, in particular using a partial reconstruction of 2D shapes from elliptic Fourier descriptors, in order to best reproduce the shape, angularity and texture of the aggregates using the SPHERE model. Validation of the method on 3D printed data shows relative errors of less than 3% for all measured 2D and 3D morphological characteristics, and validation on a population of synthetic objects shows relative errors of less than 6%. The results are compared and discussed with those obtained using other models based on overlapping spheres and show consistency with previous work. Finally, suggestions for improvement are given. [Display omitted] • Proposed SPHERE model uses 3D random fields to deform a mesh. • Model generates >1000 aggregates in <5 s with full morphological flexibility. • 3D printed object and numerical validation using multiscale optimization. • SPHERE can estimate 3D morphological properties from 2D image measurements. • SPHERE's adaptability showcases potential for diverse scientific applications. [ABSTRACT FROM AUTHOR]

Agglomerates are a large cluster of primary particles, which may result in the flaws of the final ceramics. Stereolithography suspensions could pose challenges to identify their coarse agglomerates without modifications to their properties; the suspensions are mostly high turbid and viscous in some cases. Any modifications, such as dilution, can alter the actual degree of agglomeration. In this study, a means to characterize the degree of dispersion was developed using the automated fineness of grind gauge. The fineness of grind gauge was visualized to determine the nature of the trapped agglomerates and their distribution. The resulted agglomerate size distribution was treated mathematically as a power law distribution in a selected region. The power law function was found to describe the degree of dispersion of suspensions, which was associated with the coarse agglomerate distribution behavior. Unlabelled Image • Identified the degree of dispersion of stereolithography suspensions. • Defined the power law coefficients of the agglomerate size distribution. • Provided a correlation between coarse agglomerate and power law exponent. [ABSTRACT FROM AUTHOR]

Image analysis and spectroscopic method of evaluation are applied on Gamma auto radiographs (GAR) to assess the effect of plutonium concentration in (U,Pu)O2 mixed oxide (MOX) fuel samples on the characteristics of the irradiated film. Results of the two different methods of GAR analysis are compared with results of the earlier studies using alpha irradiated solid state nuclear track detectors using Pu bearing fuel samples with low as well as high plutonium content. Theoretical simulations using Monte Carlo method of radiation transport were carried out for comprehension of the process of GAR under ideal conditions and results were applied for understanding the relative degree of heterogeneity in Pu bearing fuel samples and compared with that from experimental methods of analysis. [ABSTRACT FROM AUTHOR]

This study was carried out on Sille agglomerate which is a typical volcanic welded bimrock. Two precious historical monuments, Koimesis Tes Panagias Church and Sekili hill settlement carved in Sille agglomerate, have maintained their stability without any support for centuries although suffering from weathering and various stability problems. However, due to its heterogeneity and sampling difficulties, the overall strength of Sille agglomerate has not been investigated yet. This paper presents the relationships between fragmentation fractal dimension (DF), fractal dimension of rough block surfaces (DR), number of blocks (BN), and volumetric block proportion (VBP) and the overall uniaxial compressive strength (UCS) of the Sille agglomerate. By using these properties as inputs, three statistically significant empirical models were developed for estimating the UCS of the Sille agglomerate. The results revealed that the DF and DR may be good predictors to estimate the UCS of welded volcanic bimrocks, and defining the properties of blocks by means of fractal theory provides significant contribution to the estimation of the UCS. It is observed that the failure planes in the core samples predominantly pass through the boundaries between matrix and blocks, and such behavior may indicate that the weakest component of the Sille agglomerate is boundaries. Accordingly, the UCS decreases due to the high DR values which create more or further weakest zones in the bimrocks. Finally, it is concluded that the negative correlation between the UCS and the VBP was attributed to increase of the DR due to the increase of the VBP. [ABSTRACT FROM AUTHOR]

Background: Black tattoo reactions are suggested to be foreign body reactions manifested as papulo‐nodular inflammation that is associated with active sarcoidosis. Aim: To study the morphology of black and red pigment agglomerates in skin biopsies from tattoo reactions, referenced to clinical diagnoses. Method: Agglomerate count, area, width, height, circumference and circularity were measured in 161 patients by light microscopy (Olympus BX51™); 161 unstained skin biopsies from 64 black tattoo reactions and 97 reactions in red tattoos with allergy. Images (Jenoptic Gryphax RGB camera) were taken through a 40× objective using immersion oil. Computerised analysis of agglomerates was performed using ImageJ software. Student t test, chi‐square test, Fisher Exact test, ANOVA and Bonferroni tests were applied. Results: Comparison of black and red pigment agglomerates showed no overall differences in count, area, width, height or circumference. However, in black tattoo reactions, the count of agglomerates was higher in patients with sarcoidosis (P =.009) vs no sarcoidosis. Black agglomerates were more circular shaped as compared to red, P =.023. In red tattoo reactions, agglomerates in patients with allergic cross‐reactivity were slightly more circular (P =.036) vs patients with milder allergy. The count of red agglomerates was lower in patients clinically typed excessive hyperkeratosis (P =.041) compared with other clinical types of allergy. Conclusion: Patients with reactions in black tattoos associated with sarcoidosis have increased count of pigment agglomerates vs those without associated sarcoidosis indicating that black pigment agglomeration is one among a number of factors triggering sarcoid tattoo complication. Circular shape of agglomerates may code for bioactivity. [ABSTRACT FROM AUTHOR]

Pressure filtration is a key process in ceramic forming; however, the influences of density difference in different parts of a pressure‐filtrated wet cake on subsequent drying and sintering have not yet been explored. In the present work, alumina slurries dispersed by copolymers of isobutylene and maleic anhydride (PIBM) and ammonium salt of polyacrylic acid (PAANH4) were pressure filtrated to examine the impacts of density difference in the as‐prepared wet cakes. In comparison to the wet cake produced from PAANH4, the wet cake with PIBM had much higher bulk density and smaller density difference between its upper and bottom parts (height of ~23 mm). Furthermore, in order to reveal the differences between these two wet cakes, the nature of agglomerates in their slurries was investigated. The slurry with PIBM contained agglomerates with a wider size distribution, bigger average size, and higher sphericity, producing a wet cake with a higher particle packing density and more homogeneous packing structure after pressure filtration. Hence, almost no deformation occurred in a large wet cake (280 mm × 130 mm × 20 mm) with PIBM, whereas that with PAANH4 experienced a severe deformation after sintering. [ABSTRACT FROM AUTHOR]

There is a high demand for fully automated methods for the analysis of primary particle size distributions of agglomerated, sintered or occluded primary particles, due to their impact on material properties. Therefore, a novel, deep learning-based, method for the detection of such primary particles was proposed and tested, which renders a manual tuning of analysis parameters unnecessary. As a specialty, the training of the utilized convolutional neural networks was carried out using only synthetic images, thereby avoiding the laborious task of manual annotation and increasing the ground truth quality. Nevertheless, the proposed method performs excellent on real world samples of sintered silica nanoparticles with various sintering degrees and varying image conditions. In a direct comparison, the proposed method clearly outperforms two state-of-the-art methods for automated image-based particle size analysis (Hough transformation and the ImageJ ParticleSizer plug-in), thereby attaining human-like performance. Image 1 • Deep Learning can significantly help to automate image-based PSD analysis. • The proposed method can achieve human-like performance at superhuman speed. • Image synthesis can produce lifelike SEM images, suitable for deep learning. [ABSTRACT FROM AUTHOR]

Cement raw meal particles are typical Geldart Group C particles. Due to strong van der Waals forces, the particles are cohesive, tending to form agglomerates. These agglomerates significantly influence the flow, dispersion, heat transfer and calcination of raw meal particles inside cement precalciners. Without considering the agglomeration effects of fine particles, computational fluid dynamics (CFD) simulation of precalciners may fail to accurately predict the flow and dispersion behavior. This paper presents an agglomerate-based drag model by integrating an equilibrium agglomerate size based on energy balance. The new drag is integrated into CFD and validated by simulating a pilot-scale precalciner, showing good agreement with the experimental data. [Display omitted] • Two agglomerate-based drag models for cohesive fine particles are formulated. • The new drag models are validated on CFD simulations of a cement pre-calciner. • The new drag models significantly improve the predicted temperature distribution. • The agglomeration effects on particle dispersion and heat transfer are discussed. [ABSTRACT FROM AUTHOR]

Understanding the transport mechanism in catalyst layer (CL) agglomerates is crucial to enhance Pt utilization and overall fuel cell performance. In this study, high-resolution porous agglomerates are stochastically reconstructed, and capillary condensation of water in agglomerates is directly simulated using a lattice Boltzmann pseudopotential model. On this basis, a pore-scale electrochemical model is developed to investigate the effects of agglomerate structure and operating humidity on local transport resistance and agglomerate effectiveness at different Pt loadings. The results reveal that liquid water formed above 70%RH improves the electrochemical surface area (ECSA) of agglomerates with low ionomer content. An optimum I/C of 0.4 in agglomerates is determined by balancing the activated ECSA and oxygen transport resistance. Through the comparison of local transport resistance with limiting current data, an additional oxygen dissolution resistance of 60–350 s m−1 at the pore/ionomer or ionomer/Pt interface is quantified. The lowest local transport resistance of the agglomerate is achieved at about 70%RH, while condensed water at higher humidities hampers oxygen diffusion within the agglomerate, leading to reduced Pt utilization. Agglomerate size significantly affects the local transport resistance only when excessive ionomer or liquid water severely blocks primary pores. Finally, a novel multiscale coupling strategy integrating the porous agglomerate sub-model with a continuous-scale CL model is proposed, offering innovative insights into comprehending the relationship between CL structure and the performance of proton exchange membrane fuel cells. • High-resolution porous structures of the agglomerate are reconstructed. • Quantify the interfacial dissolute resistance and permeability reduction of ionomer. • Condensed water formed above 70%RH degrades the oxygen diffusion process. • Agglomerate size affects the transport resistance when primary pores are blocked. • A multiscale coupling strategy for the pore-scale agglomerate model is proposed. [ABSTRACT FROM AUTHOR]

[Display omitted] • Behaviour of loaded bubbles at water–air and water-froth interfaces. • Pulp-froth interface and particle detachment. • Role of kinetic energy and bubble coalescence on interfaces. • Detachment of particles as agglomerates. • Particle dropback from the froth. Although the pulp-froth interface is thought to be very important to particle detachment and therefore overall flotation recovery, experimental evidence to back this is contradictory with recent observation indicating that detachment may not be as rigorous as previously thought. We investigate the effect of the interface (air–water and froth-water) on particle detachment as function of particle size, density, hydrophobicity, and bubble sizes. Bubbles were loaded with particles of size classes between 53 µm and 1018 µm and were allowed to collide with the a given interface while videos of the interaction were taken. using a high-speed video camera. The results from the experiments indicate that particles attached to bubbles do not detach when a loaded bubble collides with the interfaces. Further, the particle properties - (size and type of the particles, and contact angle) and bubble had no influence on particle detachment at the interface. However, the particles attached as agglomerates dropped off upon impact and as a result of bubble shape deformations. Further, observations from the water froth interface show that the impact upon collision can significantly shake of particles from within the froth while the particles on the bubble remain attached. Under our experimental conditions, coalescence was also observed not to be as rapid, with loaded bubbles remaining in contact with the water-froth interface for not less than 26 s. [ABSTRACT FROM AUTHOR]

We developed a reconstruction simulation model for a catalyst layer of a polymer electrolyte fuel cell to elucidate the effect of the size and shape of the catalyst agglomerates on the cell performance. The geometry of the catalyst layer was obtained by simulating the packing of carbon black agglomerates in ink modeled as multisphere objects by the discrete element method. Electrochemical reaction and mass transfer were modeled based on the resulting three-dimensional geometry of the catalyst. Both the size and shape of the agglomerate significantly influence the catalyst structure and performance. Branched agglomerates lead to higher porosity, larger pore sizes, and better cell performance. For each agglomerate shape, there is an optimum size at which the performance is the maximum, because of the optimum trade-off relationship between the oxygen diffusion and proton conduction. Understanding the mechanism of the catalyst formation can aid the design of catalysts to improve their performance. Image 1 • A model of a fuel cell catalyst was developed based on packing of agglomerates. • Electrochemical reaction and mass transfer was simulated on the resulting geometry. • Branched agglomerates resulted in a higher porosity and increased pore size. • The agglomerate size increased oxygen void diffusion but reduced proton conduction. • This study can increase our understanding to improve the fuel cell performance. [ABSTRACT FROM AUTHOR]

The scope of the study is to determine the influence of the addition of different amounts of carob (CP), cinnamon (CNP), and ginger (GP) powders and fluidized bed agglomeration process on the moisture content, water activity and powder properties of milk powders as well as powder yield and the energy consumption of the drying and agglomeration operations. CP, CNP, and GP were directly added to whole milk at different concentrations (1-8% by weight), mixed for 30min and filtered by crude filter paper. Then, the filtrate was spray dried at the inlet and outlet air temperatures of 160 and 80 °C respectively. The powder yield ranged between 55.57-67.07% for milk powder with CP (MPCP), 45.48-61.04% for milk powder with CNP (MPCNP), and 42.42-46.93% for milk powder with GP (MPGP). The addition of the powders decreased the total drying time and energy consumption of the drying process (p<0.05). The agglomeration process was performed at 1.8 m/s, and 80 °C for 15 min. During this process, water (1:0.1 weight: weight, water: powder) was added to powders as a binder. Agglomerates have higher moisture content (3.45-4.60%, wet basis) and water activity (0.171-0.257) values compared to corresponding powders. The solubility times of powders decreased with the increasing amount of ingredients. Higher bulk (200-259 kg/m³) and tapped (339-400 kg/m³) density values were obtained from MPGP compared to other powders. Agglomeration process improved the flow properties of milk powders and increased the bulk and tapped density values. The long solubility times of milk powders (194-244.5 s) reduced to 10-50 s by means of the applied agglomeration process. [ABSTRACT FROM AUTHOR]

SnO nanosheets decorated with P25 have been synthesized by ultrasonic reaction to form SnO/P25 composites. Photocatalytic properties of the composites for the visible light degradation of MO were evaluated. Results revealed that P25 amounts significantly influenced the morphology, the absorbability of the visible light region, and the photocatalytic properties of samples. SEM results showed that the addition of small amounts of P25 may obtain micro-flower morphology with P25 nanoparticles loaded on the SnO nanosheets. Dense P25/SnO agglomerates with a size of approximately 2–3 μm were acquired by further increasing P25 content. TEM observations indicated that P25 was closely deposited on the SnO nanosheets. SnO/P25 composites had much higher absorption in the visible light zones than that of SnO sample or P25. The photocatalytic activity results indicate that the P25/SnO composites containing tiny P25 possess excellent catalytic activity for MO degradation. The SnO/2% P25 composites exhibited the highest photocatalytic properties, degrading 99.3% of MO for 60 min. [ABSTRACT FROM AUTHOR]

In order to obtain uniformly dispersed ？ non-contaminated and non-agglomerated GNPs ？ the agglomerated GNPs were dispersed by ultrasonic treatment technology and the main influencing factors？ the effects of ultrasonic power and ultrasonic time in the dispersion process for GNPs ？ were studied. Characterization, detection and analysis of the morphology, size and structure of ultrasonically processed GNPs were studied by field emission electron microscopy？ transmission electron microscopy, Fourier transform infrared spectroscopy, Xray photoelectrori spectroscopy, Raman spectroscopy and atomic force microscopy analysis. The results show that pro longing the ultrasonic time or increasing the ultrasonic power could significantly improve the dispersion effect of GNPs？ but correspondingly reduce the size of GNPs to a certain extent and generating a large number of edge defects. When the ultrasonic power or ultrasonic time was too large？ vacancy defects would even be generated. When the ultrasonic power was 960 W and the ultrasonic time was 4 h, the dispersion effect of GNPs was the best, and the degree of fragmentation was relatively low. [ABSTRACT FROM AUTHOR]

The characteristics of gas–solid fluidized beds, which are often applied for the separation of minerals, are affected by the moisture carried by wet coal. 3D X-Ray Microanalyser (3D-XRM) and electrical capacitance tomography (ECT) were used to monitor the moisture transfer process of wet coal, as well as the structure and distribution of agglomerates formed in the bed. The fluidization performance of the bed was then studied by a high-speed camera system and pressure drop measurement. The moisture in the wet coal was found to be mainly in the form of free moisture or external moisture on the coal surface. The free moisture mainly formed agglomerates of magnetite, whereas the external moisture caused magnetite to adhere to the surface of raw coal. The agglutinating value of wet coal is mainly affected by external moisture and size fraction, but has little correlation with coal density. The tendency of the formed agglomerate content can be divided into three stages: (i) When the external moisture is 1%, no agglomerates appear in the bed; (ii) When the external moisture reaches 2%, agglomerates are present in the form of magnetite adhering to the coal surface; (iii) When the external moisture exceeds 3%, magnetite adhered to the coal surface is dominant for the agglomerates. Excess moisture will cause the magnetite itself to agglomerate and participate in the internal particle circulation in the bed. At the same time, the moisture content plays a crucial role in the fluidization behavior of the bed. As the moisture content increases, the fluidization behavior of the bed begins to transition from group B to An under low moisture content (<0.25%), and eventually to group C for high moisture (>0.75%). Unlabelled Image • The formation machine of agglomerates under the moisture in the bed was studied. • The fluidization performance was observed by a high-speed camera system. • The moisture transfer of wet coal in the fluidized bed was explained by ECT. • The effect of the moisture on the separation performance was revealed. [ABSTRACT FROM AUTHOR]

The paper considers the processes of direct production of iron from ores, which a re called solid-phase reduction processes. A technology for the production of metallized agglomerate is proposed, consisting of two stages: sintering of agglomerate and subsequent metallization of hot intact sintered material. The combined sintering process and metallization with the products of natural gas conversion of the agglomerate at an elevated pressure of the gas phase resulted in the metallization of 50 - 68% metallized sinter. [ABSTRACT FROM AUTHOR]

This paper presents a review of studies of the combustion of composite propellants containing a combined fuel based on aluminum and boron. A method for studying the combustion of large particles of the combined Al + B fuel in air is described. Burning agglomerated Al/B particles 300–700 μm in diameter were obtained by ignition of miniature pieces of a composition containing 32% binder and 68% micron-sized aluminum and boron powders in the ratio Al/B = 81/19 placed in a burning metal-free sample. Agglomerates formed by the merger of many small particles burned in free fall in air. Procedures are described that were used to process video records of the combustion process and study condensed combustion products (combustion residues of agglomerates) in order to determine the burning time and analyze the transformation of the combined fuel into oxide. [ABSTRACT FROM AUTHOR]

By considering the parametric variation of an individual boron particle in a boron agglomerate, the heat transfer, and the mass transfer between the boron particle agglomerate and the surroundings, an ignition and combustion model of a boron agglomerate is proposed. An experiment of a ramjet combustor using a boron-based slurry fuel is designed and operated for the purpose of validating the ramjet configuration and verifying the combustion of boron particles. Then a mathematical model for simulating a multiphase reacting flow within the combustor of a boron-based slurry fuel ramjet is established. Kerosene droplets and boron particles are injected discretely to the burner flowfield, and their trajectories are traced using the discrete phase model. The influence of the agglomerate size, bypass air mass flow rate, initial boron particle diameter, and boron particle content on the combustion efficiency of the slurry fuels is analyzed in detail. The results show that the combustion efficiency decreases with an increase in the agglomerate radius, initial boron particle diameter, and boron particle content. The combustion efficiency increases with an increase in the mass flow rate of bypass air. If the agglomerate diameter is greater than 100 μm or the bypass air mass flow rate is smaller than 50 g/s, the boron particles cannot be fully burned. [ABSTRACT FROM AUTHOR]

The combustion of 81/19 Al/B agglomerates with a diameter of 320–780 μm in free fall in air was first studied using model monodisperse agglomerates. The dependence of the burning time on size was determined. Burning residue particles have been studied by morphological, chemical, mass, particle size, and elemental (EDS) analyses. It has been found that the essential distinctive features of the combustion mechanism of Al/B agglomerates compared to aluminum are a long combustion duration; a specific core-shell structure of the particles, with boron present in the core and absent in the shell; slight changes in particle mass and diameter during combustion. [ABSTRACT FROM AUTHOR]

• The effect of external additive on fumed TiO 2 was studied by the thermal treatment. • The TiO 2 with SiO 2 showed high rutile content and excellent dispersibility. • The TiO 2 with calcium stearate showed high rutile content and low dispersibility. • The rutile content is related to the agglomerate of TiO 2 before thermal treatment. The effect of external additives on the synthesis of fumed TiO 2 with a high rutile structure content was studied. The focus of this investigation was on the external additive species, agglomerates of the fumed TiO 2 before and after the thermal treatment. The transformation ratio from the anatase to rutile structure of the thermally-treated fumed TiO 2 was investigated as a function of the fumed TiO 2 agglomerate before the thermal treatment. Small agglomerated powders resulted in a decrease of transformation temperature. Two novel results were obtained in this investigation. One was a new fumed TiO 2 with a 100% rutile structure having an excellent dispersibility being successfully synthesized by the thermal treatment of AEROXIDE® TiO 2 P 25 with a small portion of AEROSIL® R 972. The other was the remarkable acceleration of the transformation from the anatase to rutile structure and grain growth/sintering of the thermally-treated fumed TiO 2 observed at a relatively low thermal treatment temperature by the oxidation reaction of calcium stearate as an external additive. [ABSTRACT FROM AUTHOR]

Highlights • A kinetic model developed to predict agglomerate diameter in emulsion region. • Agglomerate diameter as a function of the bed voidage and gas velocity. • Veracity of model validated by variations of target compound and its concentration. Abstract To predict the agglomerate diameter formed by nano-sized Titania powders (P25) in emulsion region of annular fluidization bed photocatalytic reactor (AFBPR), a kinetic model was developed based on an assumption of a target molecule only reacts on the active site of an agglomerate in illumination field. The results indicated that the agglomerate diameter was a function of bed voidage and gas velocity for a given photocatalytic oxidation. It was obvious that the agglomerate diameter decreased with increasing bed voidage, and decreased along the heighten of fluidized bed, which were confirmed by the experimental results. The agglomerate size decreased with gas velocity increased, validated by the estimated data of force model. Finally, the veracity of kinetic model was validated by variation of gaseous compound types and their concentrations, which suggested that this kinetic model was feasible for photocatalytic oxidation of gaseous pollutants. This investigation highlights the novel method to describe the relationship between agglomerate diameter distribution formed in emulsion region of AFBPR and photocatalytic reactivity. [ABSTRACT FROM AUTHOR]

Abstract In this paper, a complete characterization of particulate matter (PM) emitted by a low-scale biomass combustor was performed. Samples were collected in three different zones of the installation (in-flame, boiler outlet and chimney outlet) using the thermophoretic sampling (TPS) method, and the different particle structures present in the biomass were studied from a chemical and a morphological point of view. Five types of particles were found: soot agglomerates, organic films, organic particles with imbibed fibrous structures, condensed tars and condensed inorganic salts. Transmission electron microscopy (TEM) was used for shape description, and scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDX) was used for determining elementary composition. Specifically, soot agglomerates were submitted to a deeper characterization in terms of fractal descriptors, obtaining values for primary particle diameter, d po , of 21.7 ± 8.4 nm, 21.4 ± 6.6 nm and 26.0 ± 5.9 nm for the three sampled zones, as well as values for fractal dimension, D f , between 1.40 and 2.60 and fractal prefactor, k f , between 2.20 and 2.40. The results were in agreement with other soot formation sources and showed an increasing tendency to cluster growth and compaction with the residence time inside the facility, being higher as they went further from the combustion zone. Fractal descriptors were not fairly influenced by the applied thermal treatment. Highlights • Morphology and composition of biomass PM families was performed using TPS sampling. • The organic thin-film was the more frequent type and soot agglomerates were only 7%. • d po , D f and k f show soot's growth and compaction as a function of residence time. • VOC's evaporation is fulfilled by the action of the TEM electron beam. [ABSTRACT FROM AUTHOR]

The tensile strength is an important material attribute of granular products, and diametrical compression is one of the most common methods to determine the tensile strength of the agglomerate. In this study, three-dimensional diametrical compression tests of annular agglomerates with various bonding strengths, i.e. interfacial energies and internal holes, are for the first time modelled by the Discrete Element Method (DEM) with the JKR theory. The fracture patterns and tensile strengths of annular specimens are analysed and compared with those of disc specimens. It is found that annular specimens show complete tension failures with progressive fractures along the loading diameter towards the central hole, while the disc specimens show wedge-shaped shear fractures near the platens. The results also show that the tensile strengths of annular specimens are linear with the surface energy, whereas increase with the size of internal hole and then decrease with the size of internal hole. A dimensionless parameter is introduced to analyse the failure mechanism of the agglomerate. This parameter quantifies the ratio between the external force exerted by the platens and the cohesive force among bonded particles. The proposed parameter emphasises the crucial influence of the internal hole size of an annular agglomerate and bonding capacity on its tensile strength. [Display omitted] • Fracture patterns and tensile strengths of annular specimens and disc specimens are modelled. • Effects of bonding capacities and hole sizes on diametrical compression tests are analysed. • A dimensionless parameter is proposed to characterise the bonding capcity and tensile strengths. [ABSTRACT FROM AUTHOR]

The morphological characterization of aggregates or agglomerates using image analysis is an increasingly active area of research, whether in the chemical, environmental or civil engineering industries, in the food industry or in the medical and pharmaceutical fields. The final properties of agglomerates are often related to their size and shape distribution, and the morphology of aggregates can in turn influence the efficiency of industrial processes or their impact on health and the environment. Since the morphology of aggregates has such a considerable influence, tools are needed to measure, characterize and quantify it, in particular by image analysis. Therefore, this article proposes to apply the method of Systematic Literature Review (SLR) to answer a series of questions, such as which are the most popular imaging devices, the size and type of aggregates studied, the most active research fields, the most popular image analysis techniques, the most represented authors and journals and, above all, the main morphological characteristics measured, with their definition given in the supplementary material. For this purpose, the SLR method is described in detail, as well as the research questions and the protocol followed. A total of 145 articles were selected based on the inclusion and exclusion criteria, and the data collected are presented. All morphological characteristics measured and reported are presented, described, and defined for a total of more than 45 different morphological characteristics and more than 110 definitions. Techniques for image analysis, aggregate characterization, and the full range of imaging devices used are listed. Finally, other reviews on the study of aggregates or agglomerates are mentioned, and the main points of this article are summarized in a conclusion with some guidelines for future authors. [Display omitted] [ABSTRACT FROM AUTHOR]

Soot emissions from vehicles have effects not only on public health but also on the Earth's radiative balance. This pollutant is the main absorber of visible solar radiation and is considered to be the second factor contributing to global warming after CO2. Large and compact soot agglomerates have a higher single-scattering albedo than small and irregular ones. Among morphological and optical studies, most of them focus on the effect of the particle size, but not so many on the irregularity of agglomerates. In this work, the methodological approach is based on the combination of original experimental techniques (in-situ measurement of morphological and optical properties of soot particles emitted from a vehicle on a rolling bench) with theoretical developments (using fractal analysis and optical modelling). A typical conventional European road vehicle was used as a soot generator. Individual soot agglomerates were sampled and visualized with transmission electron microscopy (TEM), and their images were subjected to digital treatment and their morphological parameters were used as input for modelling. In addition, a double dilutor-Differential Mobility Analyzer (DMA)-Condensation Particle Counter (CPC)-Cavity Attenuated Phase Shift spectrometer (CAPS) assembly was used, which allows for classification of particles based on their mobility diameter and to simultaneously measure the optical extinction and scattering coefficients of the agglomerates. It was observed that, in general, the diameter of gyration obtained from TEM images underestimate the electrical mobility diameter, especially for large agglomerates. It was also observed that the diameter of primary particles and the power-law prefactor increase with the agglomerate size, while opposite trend was found for the fractal dimension and for the coordination number. Both the mass-specific absorption and scattering cross-sections (MAC and MSC) of agglomerates were observed to decrease with increasing agglomerate size, as consequence of decreasing fractal dimension. [Display omitted] • Electric mobility diameters are overestimated with respect to diameters of gyration. • No significant morphological changes were found with respect to vehicle velocity. • Larger agglomerates show lower fractal dimensions and lower coordination index. • Both absorption and scattering optical specific cross sections decrease with size. • Scattering albedo of agglomerates is dominated by hydrocarbon content and size. [ABSTRACT FROM AUTHOR]

Coagulation of nanoparticles from the free-molecular to the transition regime under a high-temperature environment is investigated by coupling Langevin Dynamics (LD) model with agglomeration and finite-rate sintering. The effect of temperature on the evolution of particle size and structure is investigated, variations in agglomeration-sintering dynamics are obtained. The fractal dimension of agglomerates at different temperatures can be expressed as a function of the ratio between the characteristic collision time and sintering time. The overall collision frequency (β) is enhanced by the polydispersity and fractal properties of agglomerates compared to the monodisperse collision kernel functions. Finally, the classic function of β is modified based on the LD simulations and used in a one-dimensional population balance equation, which reproduces a better prediction of the evolution of particle size distribution during particle coagulation with agglomeration and sintering. [Display omitted] • Langevin Dynamics model is coupled with agglomeration and sintering. • Effect of temperature on particle-to-agglomerate evolution is discussed. • Evolution of nanoparticle morphology depends on ratio of characteristic times. • Collision frequency is enhanced by polydispersity and fractal dimension. • Modified collision frequency function is used in a simple population balance model. [ABSTRACT FROM AUTHOR]