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Rat lungs and lung-associated lymph nodes from 14 inhalation studies with chemically different particulate materials were histopathologically re-evaluated, and the bronchoalveolar lavage fluid (BALF) data and lung burden analyses were compared. All investigated substances caused similar lesions. For most substances, 1 mg/m3 of respirable particulate matter was established as the borderline for adverse morphological changes after the 90-day exposure period, confirmed by the increase in polymorphonuclear neutrophils in BALF. Possible reversibility was demonstrated when recovery groups are included in the study especially allowing the differentiation between regeneration or progressing of inflammatory changes during the recovery period. It was concluded, that the major driver of toxicity is not an intrinsic chemical property of the particle but a particle effect. Concerning classification for specific target organ toxicant (STOT) repeated exposure (RE), this paper highlights that merely comparing the lowest concentration, at which adverse effects were observed, with the Classification Labelling and Packaging (CLP) regulation (EC) no. 1272/2008 guidance values is inappropriate and might lead to a STOT classification under CLP for a large part of the substances discussed in this paper, on the basis of typically mild to moderate findings in rat lung and lung-associated lymph nodes on day 1 after exposure. An in-depth evaluation of the pathologic findings is required and an expert judgement has to be included in the decision on classification and labeling, evaluating the type and severity of effects and comparing these with the classification criteria. • Comprehensive histopathologic review, Comparison of 14 particulate materials [ABSTRACT FROM AUTHOR]

Inhalation toxicity testing of particulate materials is mandated for classification. According to CLP, particulate materials should be tested as marketed and many particulate materials are marketed as non-respirable particles. However, OECD TG 413 requires exposure to particle sizes that are respirable and reach the alveoli. The requirement for exposure of rats to respirable particles is thus in contrast to CLP and requires the application of high shear forces. The exposure to artificially small particles causes a number of issues that hamper the interpretation of the results of the testing. These issues are aerosol altering in the exposure system, assessment of the adversity of the inflammatory lung responses, inclusion of recovery groups, and extrapolation of the results to humans exposed under occupational condition. In addition, effects of many particulate materials after testing according to OECD 413 are not intrinsic properties, but a general reaction of the lung to the deposited material, show very similar NOAECs for chemical diverse materials, and often are completely reversible. • Inhalation toxicity testing of particulate materials is mandated for classification. • Particulate materials should be tested as marketed. • This requirement is thus in contrast to CLP. • The exposure to artificially small particles causes a number of issues. • Issues are aerosol altering in the exposure system, the adversity of the inflammatory lung responses, inclusion of recovery groups, and extrapolation of the results. [ABSTRACT FROM AUTHOR]

Microwave remote sensing is significantly altered when passing through clouds or dense ice. This phenomenon is not unique to microwaves; for instance, ultrasound is also disrupted when traversing through heterogeneous tissues. Understanding the average transmission in particle-filled environments is central to improve data extraction or even to create materials that can selectively block or absorb certain wave frequencies. Most methods that calculate the average transmitted field assume that it satisfies a wave equation with a complex effective wavenumber. However, recent theoretical work has predicted more than one effective wave propagating even in a material which is statistically isotropic and for scalar waves. In this work we provide the first clear evidence of these predicted multiple effective waves by using high-fidelity Monte-Carlo simulations that do not make any statistical assumptions. To achieve this, it was necessary to fill in a missing link in the theory for particulate materials: we prove that the incident wave does not propagate within the material, which is usually taken as an assumption called the Ewald–Oseen extinction theorem. By proving this we conclude that the extinction length—the distance it takes for the incident wave to be extinct—is equal to the correlation length between the particles. [ABSTRACT FROM AUTHOR]

Chronic respiratory disease is among the most common non-communicable diseases, and particulate materials (PM) are a major risk factor. Meanwhile, evidence of the relationship between the physicochemical characteristics of PM and pulmonary toxicity mechanism is still limited. Here, we collected particles (CPM) from the air of a port city adjacent to a cement factory, and we found that the CPM contained various elements, including heavy metals (such as arsenic, thallium, barium, and zirconium) which are predicted to have originated from a cement plant adjacent to the sampling site. We also delivered the CPM intratracheally to mice for 13 weeks to investigate the pulmonary toxicity of inhaled CPM. CPM-induced chronic inflammatory lesions with an increased total number of cells in the lung of mice. Meanwhile, among inflammatory mediators measured in this study, levels of IL-1β, TNF-α, CXCL-1, and IFN-γ were elevated in the treated group compared with the controls. Considering that the alveolar macrophage (known as dust cell) is a professional phagocyte that is responsible for the clearance of PM from the respiratory surfaces, we also investigated cellular responses following exposure to CPM in MH-S cells, a mouse alveolar macrophage cell line. CPM inhibited cell proliferation and formed autophagosome-like vacuoles. Intracellular calcium accumulation and oxidative stress, and altered expression of pyrimidine metabolism- and olfactory transduction-related genes were observed in CPM-treated cells. More interestingly, type I-LC3B and full-length PARP proteins were not replenished in CPM-treated cells, and cell cycle changes, apoptotic and necrotic cell death, and caspase-3 cleavage were not significantly detected in cells exposed to CPM. Taken together, we conclude that dysfunction of alveolar macrophages may contribute to CPM-induced pulmonary inflammation. In addition, given the possible transformation of heart tissue observed in CPM-treated mice, we suggest that further study is needed to clarify the systemic pathological changes and the molecular mechanisms following chronic exposure to CPM.

An analysis has been completed for a comprehensive set of pressure drop data from the acceleration region of seven vertical, dilute-phase pneumatic conveyors. The data provided are for materials with terminal velocities from 2.05 to 22.4 m/s conveyed in risers with heights from 3 to 11.2 m and internal diameters from 0.028 to 0.083 m. Particle velocities derived from the pressure drop data were used to develop an equation of motion that includes terms for terminal velocity, and the distance traveled from the feed point. Despite covering a range of conditions, no effect of other variables was identified. Particle velocities were predicted by the equation of motion and used to calculate total pressure gradients that are within 97 Pa/m (95% confidence limits) of the measured values. The voidage correction of gas and terminal velocities recommended by other studies did not improve the pressure drop predictions. The spreadsheet model developed is simpler than the available complex numerical models and provides more accurate results. Acceleration lengths are longer than allowed for in many studies, and erstwhile established-flow data and correlations likely contain acceleration effects. [ABSTRACT FROM AUTHOR]

Microwave remote sensing is significantly altered when passing through clouds or dense ice. This phenomenon is not unique to microwaves; for instance, ultrasound is also disrupted when traversing through heterogeneous tissues. Understanding the average transmission in particle-filled environments is central to improve data extraction or even to create materials that can selectively block or absorb certain wave frequencies. Most methods that calculate the average transmitted field assume that it satisfies a wave equation with a complex effective wavenumber. However, recent theoretical work has predicted more than one effective wave propagating even in a material which is statistically isotropic and for scalar waves. In this work we provide the first clear evidence of these predicted multiple effective waves by using high-fidelity Monte-Carlo simulations that do not make any statistical assumptions. To achieve this, it was necessary to fill in a missing link in the theory for particulate materials: we prove that the incident wave does not propagate within the material, which is usually taken as an assumption called the Ewald–Oseen extinction theorem. By proving this we conclude that the extinction length—the distance it takes for the incident wave to be extinct—is equal to the correlation length between the particles.

The grouping and segregation error, one of the seven sampling errors defined by Pierre Gy, is related to the combined effects of gravity and characteristics of the target analyte such as particle size, density, shape, and moisture content of the particulate materials being sampled. Kinetic energy acting on particulate materials that are moved, flow, transported, or stockpiled causes the spatial distribution of fragments relative to one another to change. The grouping and segregation error is identified, quantified, and measured in relative sampling variance terms by comparing the sampling variability due to fractional shovelling (scooping) with that using a Jones riffle splitter. The relative sampling variance of low concentrations, approximately 0.01%, of steel balls, lead balls, and flakes of tungsten carbide in the host substrate indicates that, in this specific sampling space, the grouping and segregation error is primarily a function of particle density. Conclusions from the experiments are that components of the grouping and segregation error, namely the grouping factor and segregation factor, can be identified, measured, and mitigated. Whereas the grouping and segregation error has historically been considered to be less than the fundamental sampling error, these experiments suggest that it can be up to four times the fundamental sampling error depending on the density of the segregated materials. [ABSTRACT FROM AUTHOR]

Cohesive elongated particles are ubiquitous in some industrial particle and powder processing operations; however, only a few studies investigated the kinematics of such particles using a discrete element method (DEM). Therefore, in this study, a DEM-based model was used to investigate the kinematics of cohesive elongated particles agitated in a vertical axis mixer. A contact-area-proportional model accounting for sphero-cylindrical particle geometry was employed for modeling particle–particle and particle–boundary cohesion. Generally, the flow patterns of the elongated particles in the vertical axis mixer remain stable as the particle cohesion level increases from no cohesion to low cohesion. However, flow pattern differences appear when the particle cohesion level increases to high cohesion, including the formation of large agglomerates, particle adhesion to the drum base and sidewall, and a significant heap height increase owing to the large angle of repose which high cohesion particles could maintain. Overall increasing the particle cohesion level increases the mass flow rate of particles over the blade, emphasizing the importance of particle cohesion of the bed. At the condition of high cohesion, the variation of the flow rate over the blade is significantly higher than that for no cohesion or low cohesion. [Display omitted] • The kinematics of cohesive, sphero-cylindrical particles in a mixer are modeled. • When the particle cohesion level increases to high cohesion, flow pattern is significantly impacted. • At high cohesion condition, the mass flow rate over the blade and its variation are significantly increased. [ABSTRACT FROM AUTHOR]

Based on the discrete element method and hydrostatics theory, an improved Archimedes principle is proposed to study the rules pertaining to resistance changes during the penetration process of an intruder into the particulate materials. The results illustrate the fact that the lateral contribution to the resistance is very small, while the tangential force of the lateral resistance originates from friction effects. Conversely, the resistance of particulate materials on the intruder mainly occurs at the bottompart of the intruding object. Correspondingly, the factors that determine the resistance of the bottom part of the intruding object and the rules pertaining to resistance changes are analyzed. It is found that when the volume density and friction coefficient of the particles and the radius of the bottom surface of the cylindrical intruder are varied, the resistance-depth curve consists of a nonlinear segment and a linear region. The intersection of the two stages occurs at the same location h/R = 0.15±0.055. The slope of the linear stage is determined by the friction coefficient of the particles. Accordingly, the relationship between the slope and the friction coefficient is quantified. Finally, it is shown that the slope is independent of the geometry of the intruder. [ABSTRACT FROM AUTHOR]

• PM10 was characterized PM10 and instilled intratracheally to male and female mice. • PM10 induced dose-dependent inflammatory response followed by pathological lesions. • PM10 exposure seemed to affect to the reproductive toxicity-related endpoints. • Stillbirth was observed in three mice among eight dams exposed to the maximum dose. • Expression of hypoxia-related proteins was altered in the lung tissues and cells. Despite numerous reports that ambient particulate matter is a key determinant for human health, toxicity data produced based on physicochemical properties of particulate matters is very lack, suggesting lack of scientific evidence for regulation. In this study, we sampled inhalable particulate matters (PM10) in northern Seoul, Korea. PM10 showed atypical- and fiber-type particles with the average size and the surface charge of 1,598.1 ± 128.7 nm and −27.5 ± 2.8, respectively, and various toxic elements were detected in the water extract. On day 90 after the first pulmonary exposure, total cell number dose-dependently increased in the lungs of both sexes of mice. PM10 induced Th1-dominant immune response with pathological changes in both sexes of mice. Meanwhile, composition of total cells and expression of proteins which functions in cell-to-cell communication showed different trends between sexes. Following, male and female mice were mated to identify effects of PM10 to the next generation. PM10 remained in the lung of dams until day 21 after birth, and the levels of IgA and IgE increased in the blood of dams exposed to the maximum dose compared to control. In addition, the interval between births of fetuses, the number of offspring, the neonatal survival rate (day 4 after birth) and the sex ratio seemed to be affected at the maximum dose, and particularly, all offspring from one dam were stillborn. In addition, expression of HIF-1α protein increased in the lung tissue of dams exposed to PM10, and level of hypoxia-related proteins was notably enhanced in PM10-exposed bronchial epithelial cells compared to control. Taken together, we suggest that inhaled PM10 may induce Th1-shifting immune response in the lung, and that it may affect reproduction (fetus development) by causing lung hypoxia. Additionally, we propose that further study is needed to identify particle-size-dependent effects on development of the next generation. [ABSTRACT FROM AUTHOR]

In this work, the reliability of a DEM model for the screening process is validated by comparing numerical results and experimental data in a laboratory-scale cross-screen. The validation is carried out in two steps. First, the linear cohesion contact model in DEM is calibrated for simulating wet coal particles. The values of cohesion energy density corresponding to different water contents are determined based on the repose angle test. Then, the screening process of the cross-screen is simulated using the cohesive DEM model and compared with the corresponding experiments. The results show that the discrete model agrees well with the experiment in various aspects. On average, the relative error of the undersize particle yield for segmented screen surface and the total screening efficiency for three different screen surfaces was about 11.8% and 5.7%, respectively. Hence the calibrated DEM model can serve as a useful quantitative tool for screening of wet coals. [Display omitted] • A specially designed cross-screen experiment apparatus was presented in detail. • Parameter calibrated wet particle model was used to simulate the screening process. • Validation in terms of undersize particles yield for each deck section was conducted. • Validation of total screening efficiency was done for three types of cross-screens. [ABSTRACT FROM AUTHOR]

Rat lungs and lung-associated lymph nodes from 14 inhalation studies with chemically different particulate materials were histopathologically re-evaluated, and the bronchoalveolar lavage fluid (BALF) data and lung burden analyses were compared. All investigated substances caused similar lesions. For most substances, 1 mg/m 3 of respirable particulate matter was established as the borderline for adverse morphological changes after the 90-day exposure period, confirmed by the increase in polymorphonuclear neutrophils in BALF. Possible reversibility was demonstrated when recovery groups are included in the study especially allowing the differentiation between regeneration or progressing of inflammatory changes during the recovery period. It was concluded, that the major driver of toxicity is not an intrinsic chemical property of the particle but a particle effect. Concerning classification for specific target organ toxicant (STOT) repeated exposure (RE), this paper highlights that merely comparing the lowest concentration, at which adverse effects were observed, with the Classification Labelling and Packaging (CLP) regulation (EC) no. 1272/2008 guidance values is inappropriate and might lead to a STOT classification under CLP for a large part of the substances discussed in this paper, on the basis of typically mild to moderate findings in rat lung and lung-associated lymph nodes on day 1 after exposure. An in-depth evaluation of the pathologic findings is required and an expert judgement has to be included in the decision on classification and labeling, evaluating the type and severity of effects and comparing these with the classification criteria., Competing Interests: Declaration of Competing Interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests. All authors reports financial support was provided by SASforREACH, a consortium of the producers of synthetic amorphous silica. Nils Krueger, Tobias B. Schuster reports a relationship with Evonik Operations GmbH that includes: employment., (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)

We have developed a technique using a single apparatus to recover the inorganic and organic carbon from a small (few milligrams) aliquot of dried marine material for radiocarbon analysis. The main advantages of using a single apparatus are: 1) less sample is required, 2) decreased handling reduces contamination, and 3) less time and materials are used. Blank values of approximately 5 mu g and 19-44 mu g are obtained for the inorganic and organic carbon extractions, respectively. Delta (super 14) C results from sinking particulate organic and inorganic carbon are presented for samples collected in deep-sea sediment traps deployed for 10-30 day periods at 650 and 100 m above bottom (mab) in the northeast Pacific Ocean.

How do you take a reliable measurement of a material whose microstructure is random? When using wave scattering, the answer is often to take an ensemble average (average over time or space). By ensemble averaging we can calculate the average scattered wave and the effective wavenumber. To date, the literature has focused on calculating the effective wavenumber for a plate filled with particles. One clear unanswered question was how to extend this approach to a material of any geometry and for any source. For example, does the effective wavenumber depend on only the microstructure, or also on the material geometry? In this work, we demonstrate that the effective wavenumbers depend on only microstructure, though beyond the long wavelength limit there are multiple effective wavenumbers for one fixed incident frequency. We show how to calculate the average wave scattered from a random particulate material of any shape, and for broad frequency ranges. As an example, we show how to calculate the average wave scattered from a sphere filled with particles.

Particulate polymeric microfibers with incorporated europium(III)oxide (Eu2O3) nanoparticles were introduced as a magneto-photoluminescent multifunctional material fabricated via reversal nanoimprint lithography. To specifically address the volume properties of these guest-host particles, the guest, Eu2O3, was milled down to an average particle size of 350 nm in diameter and mixed with the host-polymer, AMONIL®, before in situ hardening in the imprint stamp. The variation of the fabrication process parameters, i.e. delay time, spin coating speed, as well as the concentration of Eu2O3 nanoparticles was proven to have a significant impact on both the structure quality and the stamp release of the microfibers with respect to the formation of a thinner residual layer. Structural characterization performed by SEM revealed optimum fabrication process parameters for a homogeneous spatial distribution of Eu2O3 nanoparticles within the microfibers while simultaneously avoiding the formation of undesired agglomerates. The magneto-photoluminescent properties of Eu2O3 nanoparticles, i.e. a red emission at 613 nm and a paramagnetic response, were found to be superimposed to the optic and the diamagnetic behaviors of AMONIL®. The results imply that guest-host interdependence of these properties can be excluded and that the suggested technique enables for specific tailoring of particulate multifunctional materials with focus on their volume properties. [ABSTRACT FROM AUTHOR]

The powerful modern toolbox of hybrid Process Mineralogy for flowsheet development uses best practice sampling as one of its tools. In this paper, the three key components of best practice sampling are reviewed with case studies. These three components are: 1. Minimum sample mass. 2. Rules of unbiassed sampled extraction. 3. The safety line. These excellent models and rules are not commonly taught in undergraduate programmes. In this review paper, which is intended as an introductory reference for those practitioners in Process Mineralogy who have not had exposure to the sampling models, simple and practical explanations are presented for reference. It is shown that finer particle size distributions lead to smaller minimum sample mass requirements. While sampling theory allows us to estimate the error involved obtaining a mass of sample for mineralogical analysis it is also useful to account for errors in the process mineralogy measurements themselves. Examples of the confidence intervals on liberation measurements made on high- and low-grade samples are provided to illustrate the importance of sample size—specifically measuring sufficient numbers of particles—in these analyses. [ABSTRACT FROM AUTHOR]

The supplemented scheme for determination of phosphorus forms in natural waters was tested for the River Prut.

In this work, the combined effects of vibration parameters on the circularly screening processes are analysed based on the Taguchi orthogonal experiment method. First, numerical investigations of the screening process including the average particle velocity and screening efficiency of different particle size fractions are presented. The variations of the average velocity and the screening efficiency of different particle size fractions for both spherical and non-spherical particle models are examined. The effect of vibration intensity on the screening process is discussed and the potential error induced by the analysis of a single factor on the screening performance is demonstrated. Then, the orthogonal test data of average particle velocity and screening efficiency for 16 cases are analysed by using the direct analysis method. The combined effects of amplitude, frequency and the inclination angle of the screen deck on the screening performance are discussed based on the calculated average values of each level of the factors. The corresponding optimal combinations of the three factors for two screening performance indexes are obtained, respectively. The effect weights of the vibration parameters on the screening performance indexes are also obtained by comparing the ranges of the factors. This work should be helpful for the understanding of the combined effects of operation parameters and provides essential references for efficient operation and optimal design of a vibrating screen. [ABSTRACT FROM AUTHOR]

A wide use of engineering and natural materials with microstructure makes it necessary to develop methods of describing mechanical behaviour of structures made of these materials. Yet, despite extensive research many aspects of fracture initiation and propagation in such materials remain unclear. We consider Mode I crack in particulate materials whose constituents are able to rotate. We model such materials in 2D as an idealised slightly cemented granular material where circular shaped thin discs are glued together. In order to model the crack, the bonds between a few pairs of discs are removed with crack opening being introduced by a thin wedge. Rotations of the particles are analysed using physical experiments, an analytical model and a DEM numerical simulation. It is found that the DEM simulations give results very close to the experimental ones. Furthermore, the particle rotations during fracture propagation can be well described by the pseudo-Cosserat continuum with constrained microrotations. [ABSTRACT FROM AUTHOR]

Chronic respiratory disease is among the most common non-communicable diseases, and particulate materials (PM) are a major risk factor. Meanwhile, evidence of the relationship between the physicochemical characteristics of PM and pulmonary toxicity mechanism is still limited. Here, we collected particles (CPM) from the air of a port city adjacent to a cement factory, and we found that the CPM contained various elements, including heavy metals (such as arsenic, thallium, barium, and zirconium) which are predicted to have originated from a cement plant adjacent to the sampling site. We also delivered the CPM intratracheally to mice for 13 weeks to investigate the pulmonary toxicity of inhaled CPM. CPM-induced chronic inflammatory lesions with an increased total number of cells in the lung of mice. Meanwhile, among inflammatory mediators measured in this study, levels of IL-1β, TNF-α, CXCL-1, and IFN-γ were elevated in the treated group compared with the controls. Considering that the alveolar macrophage (known as dust cell) is a professional phagocyte that is responsible for the clearance of PM from the respiratory surfaces, we also investigated cellular responses following exposure to CPM in MH-S cells, a mouse alveolar macrophage cell line. CPM inhibited cell proliferation and formed autophagosome-like vacuoles. Intracellular calcium accumulation and oxidative stress, and altered expression of pyrimidine metabolism- and olfactory transduction-related genes were observed in CPM-treated cells. More interestingly, type I-LC3B and full-length PARP proteins were not replenished in CPM-treated cells, and cell cycle changes, apoptotic and necrotic cell death, and caspase-3 cleavage were not significantly detected in cells exposed to CPM. Taken together, we conclude that dysfunction of alveolar macrophages may contribute to CPM-induced pulmonary inflammation. In addition, given the possible transformation of heart tissue observed in CPM-treated mice, we suggest that further study is needed to clarify the systemic pathological changes and the molecular mechanisms following chronic exposure to CPM., Competing Interests: The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Eun-Jung Park reports financial support was provided by Korea Environment Industry & Technology Institute., (© 2023 The Authors.)

The purpose of this study was to evaluate the effect of particle size distribution on the modes of flow that particulate materials will support in a pneumatic conveying pipeline. It has long been known that some materials can be conveyed in dense phase flow, i.e. a condition wherein the superficial gas velocity is below the saltation value, whereas some materials will block the pipeline under such conditions. It has also been known for a long time that there are two distinct forms of dense phase flow, generally linked to whether the material is fine (such as cement powder), or coarse (such as pellets), but until now there has been no successful method to assess the conveyability of a material based on size distribution alone. Six materials with different size grades were conveyed in a 25 mm bore pipeline, at a range of pressures up to 3 bar and gas velocities from zero to 12 m/s. The results showed that materials below a certain size would support a fluid-like dense phase mode of flow, whereas to support a low-velocity slug flow the key was to have a very narrow size distribution. Materials that satisfied neither of these criteria would not support flow at gas velocities below the saltation value. Clear trends for how throughput changes in the transition from lean to dense phase, are also demonstrated, which have major implications for pipeline sizing. A quantitative criterion for deciding on the likely conveyability of a material, based on size distribution alone, is proposed. [ABSTRACT FROM AUTHOR]

In this work, DEM results and experimental data from a specially designed circularly vibrating screening model are compared quantitatively under a range of operating conditions. The validation is carried out in two aspects. First, the motion of tracked particles is recorded using high-speed dynamic analysis system and their velocities are compared with DEM results. Second, the total screening performance indexes are compared to those predicted by DEM. Overall agreements for both spherical and non-spherical particle models are observed in both the motion of individual particles and the screening performance quantities. Generally, better agreements are found for non-spherical particle model with the particle shape reasonably considered. Quantitatively, spherical particle model is less accurate because the simplification of particle shape leads to good mobility and over-prediction of velocity and screening efficiency. The validity of the DEM model of the screening process is hence approved. The validated DEM model can be applied to perform extensive numerical studies to achieve optimal performance and better operation of such complicated and important processes in mineral processing. [ABSTRACT FROM AUTHOR]

The method of calculation of slip plane angles in compacting dispersed materials for combined action of interparticulate and external (wall) friction with method of Mohr stresses is developed. The variation range for this angles in dependence at relationship for interparticulate and external (wall) friction is determinate.

Monitoring of phosphorus content in “water-particulatematerials-bottom sediments system” for river Prut. Seasonal and spatialdynamics of phosphorus forms in water, particulate materials and bottomsediments of river Prut was elucidated. The scheme for determination ofphosphorus forms in water and particulate materials according to World HealthOrganization classification was evaluated. Additionally, this scheme was tested forestimation of phosphorus content in bottom sediments. The supplemented schemeallows the analysis of the phosphorus forms for the entirely system “water –particulate materials – bottom sediments”, extending possibilities for interpretationof phosphorus dynamics in natural waters.

Mechanized coal mining generates a substantial amount of fines that represents significant economic value. Coal fines had several applications, such as gasification, liquefaction, combustion, and beneficiation, but also pose health and safety hazards. Particle size and particle size distribution (PSD) literature on fine coal are highly limited. In this study, PSD of laboratory ball- and gyro-milled lignite and hard coal using machine vision analyzes was determined and compared with standard mechanical sieving. The developed machine vision ImageJ plugin utilized length- and a new width-based sieveless volume-based analysis for PSD evaluation. The plugin automated PSD analysis with high speed, and produced better insight of the fine coal (− 300 μm) PSD characteristics through textual and visual outputs. The method of analysis, coal, and mill types, produced statistically significant differences between these variables more on cumulative undersize and less on PSD parameters using pooled data. Ground fine coal PSD exhibited an unimodal normal distribution, and can be classified poorly-graded, positively skewed and leptokurtic, very well-sorted, symmetrical, and platykurtic to mesokurtic. Mechanical sieving PSD characteristics, in general, fell between machine vision width- and length-based characteristics. Unlike limited standard sieves of mechanical sieving, the machine vision methods, with limitless virtual sieves, accurately analyzed the PSD with the necessary number of sieves. The outlined machine vision methods can be readily utilized to analyze similar particulate materials. [ABSTRACT FROM AUTHOR]

Inhalation toxicity testing of particulate materials is mandated for classification. According to CLP, particulate materials should be tested as marketed and many particulate materials are marketed as non-respirable particles. However, OECD TG 413 requires exposure to particle sizes that are respirable and reach the alveoli. The requirement for exposure of rats to respirable particles is thus in contrast to CLP and requires the application of high shear forces. The exposure to artificially small particles causes a number of issues that hamper the interpretation of the results of the testing. These issues are aerosol altering in the exposure system, assessment of the adversity of the inflammatory lung responses, inclusion of recovery groups, and extrapolation of the results to humans exposed under occupational condition. In addition, effects of many particulate materials after testing according to OECD 413 are not intrinsic properties, but a general reaction of the lung to the deposited material, show very similar NOAECs for chemical diverse materials, and often are completely reversible., Competing Interests: Declaration of Competing Interest Each author certifies that their freedom to design, conduct, interpret, and publish research was not compromised by the sponsor., (Copyright © 2023 The Authors. Published by Elsevier B.V. All rights reserved.)

An original modeling-based microwave imaging technique for determining the volume fraction of solid material in dielectric powders is described. The desired characteristic is determined by analyzing S-parameter measurements in a waveguide containing the sample with the help of an artificial neural network trained by data from 3D FDTD simulation. The powder sample is represented by a mixture of air and millimeter-scale particles reproduced in the FDTD model. Computational tests with 20 to 40 mm cubic samples of SiC and ZrO2 powders in WR340 show that the solids volume fraction is determined with less than 5% error. [ABSTRACT FROM AUTHOR]

Constitutive models of particulate materials often rely on distances between the current stress state in stress space and various surfaces. Examples of these surfaces include the bounding surface and the dilatancy surface. This paper proposes a rigorous method for determination of distance to a surface in stress space. It starts by examining operations on stress variables defined in the $$\pi $$ plane. Algorithms for determination of an image point on a surface are then presented as a function of the location of the current stress state with respect to the surface. For points within the surface, the bisection method is used; otherwise, the secant method is used. The paper shows that implementation of the proposed algorithm locates the image point on a surface in stress space with accuracy and rigor, providing an accurate measure of the distance to the surface that can be used in hardening or flow rules. [ABSTRACT FROM AUTHOR]

A behavior investigation of particulate materials plays an important role by the behavior prediction of particulate materials with their transport, handling and storage. This properties, their prediction followed processing is a highlight to ensure a free-flowability of this particulate materials in transport systems. Property investigations, e. i. particle morphology, creation of a surface patterns focus with a perfect estimation of a dependence of this properties on important aspects ensuring a permanent and continual material flow in transport systems no matter with material structures.

In the present work, TiAl-based intermetallic matrix composite with second phase reinforcement as Ni-P-coated carbon and graphite powders were synthesized by mechanical alloying route. Graphite powder (20–30 µm) and elemental carbon powders (1–5 µm) were coated with Ni-P by the electroless coating technique, which was added to the elemental powder mixtures of Ti-48Al-1%Cr -1%Nb with 1% composition of either of the two. The powder mixtures were subjected to mechanical alloying at 300 rpm up to 250 h using toluene as a process control agent. The samples were collected after 25 h duration and characterized. The formation of TiAl (γ) and Ti3Al (α2) phases are confirmed by x-ray diffraction. The formations of these phases were found after milling for 75 h in case of graphite addition and 100 h in case of carbon addition in the intermetallic matrix. The mechanically alloyed samples milled for different extents of time were examined by a field emission scanning electron microscope (FESEM) and energy dispersive x-ray (EDAX) spectroscopy; the grain size was determined to be in the size range of 140–189 nm for the mechanically alloyed mixture. [ABSTRACT FROM AUTHOR]

During the sampling of particulate mixtures, samples taken are analyzed for their mass concentration, which generally has non-zero sample-to-sample variance. Bias, variance, and mean squared error (MSE) of a number of variance estimators, derived by Geelhoed, were studied in this article. The Monte Carlo simulation was applied using an observable first-order Markov Chain with transition probabilities that served as a model for the sample drawing process. Because the bias and variance of a variance estimator could depend on the specific circumstances under which it is applied, Monte Carlo simulation was performed for a wide range of practically relevant scenarios. Using the 'smallest mean squared error' as a criterion, an adaptation of an estimator based on a first-order Taylor linearization of the sample concentration is the best. An estimator based on the Horvitz-Thompson estimator is not practically applicable because of the potentially high MSE for the cases studied. The results indicate that the Poisson estimator leads to a biased estimator for the variance of fundamental sampling error (up to 428% absolute value of relative bias) in case of low levels of grouping and segregation. The uncertainty of the results obtained by the simulations was also addressed and it was found that the results were not significantly affected. The potentials of a recently described other approach are discussed for extending the first-order Markov Chain described here to account also for higher levels of grouping and segregation. Copyright © 2013 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Abstract: This paper discusses the resilient behaviour of various materials of high rigidity, high elasticity and of particulate materials. The resilient behaviour is measured by the resilient modulus (Mr)test which is the mechanical response of soils to a dynamic cyclic load which simulates traffic loading conditions and it is an important parameter in the design of both flexible and rigid pavements. The materials used are of a concrete cylinder, a rubber sample and particulate materials which are sands of different particle size and shape classification. The design resilient modulus follows a constitutive model and it is used to compare the resilient behaviour of each material. The constitutive model shows that the design resilient modulus is affected by the particulate characteristics and how it can be related to a stiff and flexible material. [Copyright &y& Elsevier]

Abstract: The total mass of material globally transported to the oceans as particulate material is as much as 30 times greater that transported to the oceans in dissolved form. The degree to which riverine transported particles impact ocean chemistry and influence global elemental cycles depends on the reactivity of this particulate material in seawater and the relative concentration of each element. The concentrations of elements in particulate material relative to those of seawater range from less than 1 for soluble elements such as Na, to more than 107 for insoluble elements such as Al, Fe, and the Rare Earths. The reactivity of particulate material in seawater is difficult to assess directly because this fluid is saturated or supersaturated with respect to numerous elements. As such, element release from the particulate material is commonly matched by precipitation of secondary phases. The rates of element release can, however, be quantified by monitoring the isotopic evolution of seawater during its reaction with a variety of particulate material samples collected from rivers throughout the world. This research focuses on the behavior of Sr and Nd, representative of the most and least soluble elements transported to the oceans. Batch experiments demonstrate that between 0.15 and 27% of Sr is liberated from volcanic and continental particulates when interacted with seawater over 6 months. Similarly, from 1.5 to 8.5% of Nd is liberated from volcanic sediments over this timespan. This observed elemental release rate from riverine particulate material has important consequences for: (1) chemical and isotopic mass balances in the ocean; and (2) the application of the isotopic weathering proxies to the geological record. [Copyright &y& Elsevier]

Abstract: In this study we present a three-dimensional network model for the evaluation of hydraulic conductivity using new pore structure characterization algorithms. We define a porous medium from the sphere packing generated by discrete element method (DEM). The network model is based on connectivity of pore chambers linked along discretized pathway using a harmonic mean radius value computed from a series of radius-varying tubes that represent the irregularly shaped pore channel. Particle packing cases under investigation include regular packings, monodispersed, and polydispersed cases with varying porosity. Finite element analysis is implemented to obtain hydraulic conductivity values for regular packing cases for comparison. Laboratory experimentation results corroborate numerically obtained values with good agreement. Observations show the pore space should be tessellated once pore chambers are established in order to preserve the geometrical uniqueness of randomly shaped pore channel, avoid redundancy, and minimize pore channel overlap. Also, it is observed that limits must be defined for the total number of grains needed for representativeness and discretization density for the quantification of random heterogeneous pore structure. [Copyright &y& Elsevier]

Abstract: Development of human society faces two important subjects-energy crisis and environmental pollution. In this paper, Carbon smoke particulate materials (PM)-one of the main pollutants discharged by diesel were studied, and the characteristics, together with the actual state of diesel in China were introduced. In the light of the high-sulfur content of domestic diesel fuel, compulsory regeneration heater with LPG as heating source was designed, using particulate filter DPF made from Silicon carbide fiber non-woven material, which provides a technical route for the design and use of DPF blowback regeneration heater. [Copyright &y& Elsevier]

Seasonal and spatial dynamics of phosphorus forms in water, particulate materials and bottom sediments of river Prut was elucidated. The scheme for determination of phosphorus forms in water and particulate materials according to World Health Organization classification was evaluated. Additionally, this scheme was tested for estimation of phosphorus amounts in bottom sediments. The supplemented scheme allows the analysis of the phosphorus forms for the entirely system "water-particulate materials-bottom sediments", extending possibilities for interpretation of phosphorus dynamics in natural waters. The shape of dynamics of total (dissolved plus particulate) phosphorus forms in water on the middle course of river (Sculeni-Valea Mare sector), in general, has remained the same during the spring and summer seasons (2010), although the concentrations in water of phosphorus were decreased considerably during the summer as a result of the river overflows and flooding downstream of the Costesti-Stinca dam. A significant increase of total inorganic phosphorus concentrations at Valea Mare during the spring and summer seasons was recorded, and the same tendency of increasing of concentrations for organic phosphorus was registered towards the lower course of river (Leova, Cislita-Prut). The shape of dynamics of amounts of inorganic phosphorus in sediments was close during the spring and summer on the middle course of river (Sculeni-Valea Mare sector). [ABSTRACT FROM AUTHOR]

Abstract: This paper describes a three-dimensional random network model to evaluate the thermal conductivity of particulate materials. The model is applied to numerical assemblies of poly-dispersed spheres generated using the discrete element method (DEM). The grain size distribution of Ottawa 20–30 sand is modeled using a logistic function in the DEM assemblies to closely reproduce the gradation of physical specimens. The packing density and inter-particle contact areas controlled by confining stress are explored as variables to underscore the effects of micro- and macro-scales on the effective thermal conductivity in particulate materials. It is assumed that skeletal structure of 3D granular system consists of the web of particle bodies interconnected by thermal resistor at contacts. The inter-particle contact condition (e.g., the degree of particle separation or overlap) and the particle radii determine the thermal conductance between adjacent particles. The Gauss–Seidel method allows evaluation of the evolution of temperature variation in the linear system. Laboratory measurements of thermal conductivity of Ottawa 20–30 sand corroborate the calculated results using the proposed network model. The model is extended to explore the evolution of thermal conduction depending on the nucleation habits of secondary solid phase as an anomalous material in the pore space. The proposed network model highlights that the coordination number, packing density and the inter-particle contact condition are integrated together to dominate the heat transfer characteristics in particulate materials, and allows fundamental understanding of particle-scale mechanism in macro-scale manifestation. [ABSTRACT FROM AUTHOR]

Abstract: It is often desirable to predict the thermal conductivity of a heterogeneous or composite material based on its composition, particularly where variations in composition are expected. In the case of particulate materials such as sand and soil the volume fraction of the solid phase is often known, while it''s thermal conductivity is not (and vice versa for the fluid phases). It is proposed that the thermal conductivity of the solid phase of granular materials may be determined simply by measuring the thermal conductivities of the material in both the bone-dry and water-saturated states and making use of a modified form of Maxwell''s conductivity model. The method was illustrated using beach sand. [Copyright &y& Elsevier]

Particulate materials are often characterized by parameters of their particle size distribution (PSD). For the purpose of PSD measurement, typically, samples are taken from a process line or a product batch, which are then dispersed and/or diluted before the PSD measurement is executed. Usually, the attention on measurement quality is focused on the measurement technique. This article focuses, in contrast, on the sample preparation, as it is often the dominant source of error in overall PSD determination. The following error sources are discussed: (1) the number of particles (sample size) taken into account; (2) the degree with which samples can represent the product batch in view of (potential) segregation; (3) partial dissolution or agglomeration of particles during dispersion/dilution; and (4) ingression of air bubbles in suspensions and emulsions before measurement. If these error sources are not addressed properly, any of them may cause very poor product characterization. [ABSTRACT FROM AUTHOR]

Abstract: Nonuniform shrinkage during sintering results from the nonuniform green density distribution in a compacted powder body and this creates a severe problem in net-shape forming. Therefore, proper selection of the process parameters, such as compaction die design, upper and lower punch displacements, and sequential tool motion, is very important for the optimum design of die compaction processing. Previously, these were guess-estimated based on experience. As a first step in developing a more scientific design technique in powder metallurgy, the equations for the adjoint variable method (AVM) for the non-steady-state uniaxial powder compaction process are derived in detail. The accuracy of the AVM is verified through the comparison of the design sensitivity with calculations performed using the finite difference method. [Copyright &y& Elsevier]

A portable free-fall electrostatic separator capable of analyzing gram quantities of charged powders is presented. Unlike a Faraday pail, in which only the net average charge-to-mass (Q/M) ratio of the particles sampled by the instrument is measured, an electrostatic separator is capable of separately measuring the charge-to-mass ratios of positively and negatively charged sampled powders. Thus, with an electrostatic separator it is possible to measure the mass fractions of powders that are charged with different polarities and the respective charge-to-mass ratios, along with the mass fraction of particles that are uncharged or charged below a threshold level. We describe a method of measuring the total charge of the collected particles in real time by incorporating an electrometer to integrate the current flowing through the collecting electrode to the high voltage power supply. In this manner, both the total charge and total mass of powder deposited on the two electrodes are measured in near real time, providing information on charge-to-mass ratio of the aerosol cloud sampled. Such real time measurements are often needed to analyze the electrostatic charging properties of small quantities of dispersed powder, particularly in such applications where the charge characteristics are of high importance. [ABSTRACT FROM AUTHOR]

Abstract: A transition matrix approach is used to compute the scattering and absorption cross sections, as well as phase functions, asymmetry factors and forward scattering ratios, of clusters of spherical particles. In order to approach the local structure and composition of the nanosized active layer of photoelectrochemical solar cells, some clusters consist of homogeneous non-absorbing anatase spherical pigments, others have anatase particles coated with a monolayer of absorbing dye molecules, and others can consist of both uncoated and dye-coated anatase particles. Orientation average values of the volumetric scattering and absorption cross sections are computed in terms of the size of the spherical particles in the clusters and their number. The degree of scattering and absorption when considering dye-coated anatase particles in the clusters is characterized. The effect of dependent scattering on the average angular distribution of the scattered radiation is also considered. [Copyright &y& Elsevier]