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Both glycidyl azide polymer (GAP) and hexanitrohexaazaisowurtzitane (CL-20) are high-energy compounds with very promising applications. However, there are relatively few relevant studies for GAP/CL-20 aluminum-based propellants. In this paper, the CCPs of aluminum-based GAP/CL-20 propellant under different operating conditions were collected by a gas collecting device, and the physicochemical properties of CCPs were carefully studied by various modern analytical and testing instruments. The results show that the CCPs consist mainly of smoke oxide particles (~1 μm), residual oxide particles (~20 μm) and agglomerates. Residual oxide particles are widely available, but have received less attention from researchers. The agglomerates can be divided into two categories: sphere-like agglomerates and non-spherical agglomerates. Sphere-like agglomerates include cracked spheres, solid spheres, hollow spheres, and spheres with oxide caps. Surprisingly, we found an agglomerate with two caps. Non-spherical agglomerates are larger in size than sphere-like agglomerates, and the non-spherical agglomerates include irregular agglomerates, coral-like aggregates, and filamentous agglomerates. As far as we know, coral-like aggregates and filamentous agglomerates in CCPs have not been reported in the literature. Pocket theory and inter-pocket bridge theory were used to explain the formation mechanism of fine filament agglomerates. In addition, the formation mechanisms of different types of agglomerates were analyzed and sorted out. The particle size distribution of CCPs at different pressures shows that the average particle size of CCPs decreases with increasing pressure. It is hoped that this paper can provide a reference for the design of high-energy propellant formulations. [ABSTRACT FROM AUTHOR]

Copyright of Bulletin of Soil & Water Conservation is the property of Bulletin of Soil & Water Conservation Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The results of modeling the accumulation of slag residue in the combustion chamber of a propulsion system on pasty propellant obtained using a multiphase flow evolution model are presented. The influence of composition solutions on the process of slag formation is established; the significance of this process for the quality of such engines is shown. The nature of the influence of the parameters of the burning process for propellants of the type under consideration on the intensity of slag formation is determined. It is shown that the degree of involvement of metallic fuel in the agglomeration process has the greatest influence on slag formation. It has been established that the most effective ''tool'' for suppressing slag formation in the combustion chambers of paste propulsion is to change the regularities of the burning process, mainly associated with the formation of condensed products at the surface of the burning propellant.

Abstract 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 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.

The composition of a pasty propellant for small-sized space engines has been proposed. For this propellant, a research of the burning process was carried out. This research included the determination of the burning rate law, the characteristics of the agglomeration process, and the properties of the surface layer. The presence of an intermediate structure, a skeleton layer, during the burning of such propellants, and the nature of the influence of pressure, additives, and the size of oxidizer particles on this structure, have been established. The determining influence of this structure on the burning process is shown. Composition solutions that provide control over the burning rate law of such propellants are determined. These solutions make it possible to change the absolute value of the burning rate, as well as its dependence on pressure. Regularities of the agglomeration process have been established. These regularities are associated with the features of the formation of the skeleton layer, which depend on the structure of the propellant, pressure, and the presence of additives. [ABSTRACT FROM AUTHOR]

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]

The precise controlling of agglomerate dimensions within binder-treated soil remains a challenge in embankment projects. This investigation endeavors to elucidate the influence of aggregate size on key parameters such as strength, bearing capacity, volume, and unconfined compressive strength in the context of modified expansive soils. It utilized industrial wastes, such as calcium carbide slag and iron tailings sand, were incorporated and subjected to wetting and drying cycles. The investigation employed a combination of laboratory tests and microscopic testing techniques. The results showed that the water stability of the modified soil decreased with the increase of particle size. Compared with uncured aggregates, the water stability of the modified soil, particularly those containing 10 – 20 mm and 20 – 30 mm aggregates, exhibited noteworthy increases of 86.2% and 94.1%, respectively, after a 7-day curing period. It is recommended that the proportion of aggregates exceeding 20 mm in size be rigorously controlled to not exceed 10.5% during the production of modified expansive soil. Additionally, this value should be further confirmed in regions with frequent climate changes. [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]

High-protein powders (milk protein isolate (MPI) and soybean protein isolate (SPI)) were treated with maltodextrin solution (10% or 20%) or water as a binder and then subjected to fluidized-bed agglomeration. The MPI agglomerates were compared with the SPI agglomerates as a function of maltodextrin (MD) concentration. The particle size, wettability, and porosity values of SPI agglomerates were much higher than those of the raw powder when compared to the MPI agglomerates. The agglomerated protein powders with MD binder showed significantly higher solubility values than the raw powders. These tendencies were discernible in the morphological examination via SEM analysis. The dynamic modulus values of SPI agglomerates decreased with an increase in MD concentration from 10 to 20% whereas those of MPI agglomerates increased. These findings indicate that the physical, structural, and rheological properties of agglomerated high-protein powders are greatly influenced by the type of protein and the addition of MD binder. [ABSTRACT FROM AUTHOR]

One of the methods to increase the efficiency of high-temperature agglomeration of metallurgical materials is an optimization of the composition and size of the protective bed, the use of which is required for increasing the service life of the grate field of conveyor machines. The work presents research data on replacing the bottom bed with limestone and briquettes. This allows one to reduce the amount of circulating production products and increase the useful use of the working volume of the conveyor machine. Replacing the protective bed material by the fine fraction of limestone provides the grate protection from thermal effects and increases conveyor machine performance. When using briquettes upon firing pellets instead of a protective bed, the potential for productivity gains in the output of marketable products reaches 25%. [ABSTRACT FROM AUTHOR]

Copyright of Actas de Diseño is the property of Facultad de Diseno y Comunicacion, Fundacion Universidad de Palermo and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

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]

In this paper, we generalize the experience of using surfactants under laboratory and industrial conditions of the sintering process. The results of laboratory studies on the use of powdered polyacrylamide in agglomeration are presented. An analysis of the research results showed a positive effect of polyacrylamide on the performance of the sintering process and the quality of the sinter, which is associated with the formation of a more optimal granulometric composition of the pelletized charge and an increase in the temperature-thermal level of the sintering process. Based on the obtained laboratory data, recommendations for conducting industrial tests are formulated. [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 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.

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]

Business history investigation of coffee traders in Le Havre from 1920 to 1955 enables us to qualify deliberate and emergent agglomerate collective strategy. Using philosopher's contributions to the understanding of collective action (Bratman 1993), we propose a framework to differentiate deliberate and emergent strategies. The framework is used to elaborate on the resistive strategy set-up by coffee traders to the growing government pressure to supply coffee imported from the colonies. Beyond providing insight on coffee trade and business history in the early 20th century, we find our framework is consistent with the objective of differentiating emergent and deliberate strategies. [ABSTRACT FROM AUTHOR]

Oregano is a herb that is found in the wild in different parts of the world. The stick represents about 60% of the plant and is biodegradable, using lactic acid as a binding agent for the oregano stick. Waste oregano stick can be used to make biodegradable material which provides sustainable development in support and promotion of the circular economy by reducing pollution generated by chemical economy by reducing pollution generated by chemical products, agricultural waste, or products that accumulate in the environment spending years for its degradability. The originality of this project is present in the use of the oregano stick, a natural product which supplies the physicochemical characteristics of conventional raw materials used in the manufacture of wood. Oregano was collected and dried to separate the leaves from the stick. The stick was then ground, sieved at 0.118 mm and 0.025 mm, and then treated with one of two binders. For treatment 1, three samples were prepared with varying lactic acid concentrations and stick quantities with the addition of 0.3 mL of 2,2 azobisiso-butyronitrile (AIBN) 1% by weight. In treatment 2, three samples were prepared with varying polyvinyl acetate concentrations, diluted in acetone, stirred, poured into a mold, and placed in an oven at a temperature of 90 °C for 36 h. Bending and compression mechanical tests were performed on all samples; the data were analyzed by one-factor analysis of variance and Tukey test. The sample that performed the best had a value of 1.148 mm and 0.77333 kN in mechanical resistance and less elongation in compression. This sample also had a value of 0.8183 and a kN of 0.1559 with a lower mean, meaning higher resistance to bending. This sample also had the best results from the Modulus of Rupture (MOR) test with a value of 5.9958 MPas/m2. [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 the 3D morphometric characterization of latex nanoparticle aggregates. The only available information is 2D 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 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 elementary 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.

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]

Abstract—The structure, the phase composition, the physicomechanical properties, and the corrosion resistance of a precipitation-hardened composite material fabricated by hot pressing (1050°C, 30 MPa, 30 min) of powders of high-alloy ferritic steel (Fe base alloy, 30% Cr, 0.2% C) and molybdenum in an amount of 1, 5, and 10% are studied. The maximum compressive strength (1815 ± 3 MPa) is characteristic of the composite material with 10% Mo. After quenching from 1050°C, the composite material (Fe–Cr–Mo) has no χ phase, its strength decreases to 1656 ± 21 MPa, and the residual deformation (shortening) increases by 2.5–3 times. [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.

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]

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.

Objective: To morphologically analyze, by means of scanning electron microscopy (SEM), agglomerated boards made from rice husk and Hidropul 400, as well as boards made from wood fibers and glue. Methodology: For each 7,3 x 3,6 x 1,5 cm test piece, two samples were taken from the external and internal sections of each one of the boards to be analyzed. Thin-layer graphite coatings were made to each one of them, and, by means of SEM, micrographic shots were obtained in the range from 50x to 2000x. Results: It was evidenced that the panel made from rice husk had damage to its internal structure due to its porosity, the waxy layers of its coating, the high presence of silica, and the presence of water inside the adhesive, showing irregularities in adhesion between particles and low mechanical properties. Conclusions: Although the studied rice husk panel did not achieve the adequate structural properties, it has great applications for interior design. Additionally, due to its porous structure, its potential as a sound-absorbing material is considered. In the same way, the material can be improved by pre-treating the husk or combining it with other, more woody plant fibers such as wood waste, bamboo, coconut fiber, among others. Metodología: Se tomaron dos muestras por probeta de 7.3 x 3.6 x 1.5 cm en las secciones externas e internas por cada uno de los paneles a analizar, se realizaron recubrimientos de capa fina de grafito a cada una de ellas; por medio del microscopio electrónico de barrido se realizaron tomas micrográficas en rangos de 50x a 2000x. Resultados: Se evidencio que el panel fabricado con cascarilla de arroz, presentaba afectaciones en su estructura interna, debido a la porosidad, a las capas cerosas de su recubrimiento, a la alta presencia de sílice y la presencia de agua dentro del adhesivo, mostrando irregularidades en adherencia entre partículas y bajas propiedades mecánicas. Conclusiones: Aunque el panel a base de cascarilla de arroz estudiado no obtuvo las propiedades adecuadas estructurales, tiene grandes aplicaciones para el diseño de interiores, además por estructura porosa se consideran su potencial como material absorbente del sonido. De igual forma se puede mejorar el material al hacer un pretratamiento de la cascarilla o combinar con diferentes fibras vegetales más leñosas como desperdicios de madera, bambú, fibra de coco entre otros.

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]

Dissolution testing is widely used during all stages of drug development. The potential to develop an imaging analysis method to automatically detect agglomerations during dissolution testing has recently been explored. The stages of the method development were manual observation of pre-recorded videos from the dissolution testing, choice of parameters for agglomerate identification and 2-stage method validation (internal and external). This work presents the two main challenges faced during the agglomeration identification method (AIM) development a) attaining an optimal number of particle detections in a video frame and b) discerning different objects (e.g., air bubbles, single particles and agglomerates) based on their specifications.

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]

This research aimed to extract lignin from rice straw and reveal the pH value of diluted acid at which the most effective yield of lignin was precipitated. In this study, rice straw obtained from local fields in the An Giang province of Vietnam and sodium hydroxide 2 M was employed to extract lignin from rice straw. Hydrochloric acid was used to adjust the sample pH values to be in the range of 1.5-3.5. Fourier-transform infrared spectroscopy (FTIR) analysis was used to characterize the functional groups of the lignin materials. Thermogravimetric analysis (TGA) analysis was employed to supply information on the thermal decomposition of the lignin samples. Herein, the results showed that lignin precipitated at different pH values affected its thermal properties. At 700oC, the yield of the remaining lignin components were 56% at pH 2.0, but the weight loss of lignin agglomerate samples precipitated at pH 3.5 dropped to 85% because many non-lignin substances existed in the samples. The yield of the crude lignin samples obtained were 16.51, 17.66, 15.27, 14.33 and 13.26% for pH of 1.5, 2.0, 2.5, 3.0 and 3.5 respectively. The crystallite regions played an important role in the lignin structures. The spectrum peaks at pH 1.5, 2.0 and 2.5 were broader than the peaks at pH 3.0 and 3.5. The results demonstrated the highest percentage of lignin precipitate was collected at pH 2.0.

The paper presents a numerical simulation of laser separation under the influence of laser beams with wavelengths of 10.6 microns and 1.06 microns on quartz raw material used in the electronics industry in the manufacture of photomasks. The temperature fields obtained by the finite element method and the analytical solution are compared. The temperature distribution to a depth of 50 microns is almost the same when using both methods of solution, while with increasing depth the temperature difference increases by 10 %, which allows using both methods of solution, since in practice the temperature distribution in the near-surface layers, which determines the formation of agglomerates with impurity inclusions, is more important. It is revealed that the efficiency of separation of quartz raw material depends on the processing speed and the energy properties of laser radiation, which allows to choose the optimal processing parameters that ensure the effective formation of agglomerates containing impurity inclusions. Experimental studies of bi-beam laser cleaning of quartz raw material were carried out, which allowedus to determine the optimal processing parameters of quartz raw material for effective cleaning of it from impurity inclusions, that make it possible to manufacture photomasks used in the production of microcircuits with improved performance characteristics.

[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]