Characteristics Of Individual Particles Research Articles

Microcosmic characteristics of particulate matter emitted by GDI gasoline engine in plateau environment

The particulate matter samples of gasoline direction injection (GDI) gasoline engine obtained from road experiments are photographed to obtain the emission particulate matter images based on the transmission electron microscope under high altitude environment. The results show that the micro-morphology characteristics of the particulate matter emitted by GDI gasoline engine in plateau area are similar to those in low altitude area, and the main morphology is cloud-like, filamentous, flocculent, chain-like, cluster-like, like altitude contour line, etc. The images are processed by MATLAB and Python software, and the fractal dimension, average gray value and gray histogram are obtained. The fractal dimensions of the emission particulate data obtained are between 1.81 and 1.89, which has some deviation compared with the fractal dimension of the emission particulate data at low altitude of 1.58 and 1.80. With the increase of altitude, its fractal dimension increases more obviously. It can be seem from the characteristics of gray value and gray histogram of particle images that the average gray value of GDI gasoline engine particles is higher. The gray histogram distribution of 5–50 nm images is uniform, and the individual particles in the images are clear. The gray histogram of 100–500 nm images is scattered, so it is easy to extract and separate the image edge contour. 5–50 nm images are used to study the details and characteristics of individual particles, and 100–500 nm transmission electron microscope images are used to study the overall morphology of particles.

Rheological characterisation of water atomised tool steel powders developed for laser powder bed fusion by supervised and unsupervised machine learning

ABSTRACT Metal powders developed for additive manufacturing processes need to achieve specific flow characteristics to be considered suitable. However, for the relationship between powder flow and the morphological characteristics of individual particles can be difficult to establish. In this context, artificial intelligence appears to be the perfect tool to clarify the imprecision surrounding this type of interaction. The work summarised in this manuscript first uses a neural network architecture (Mask R-CNN) allowing the segmentation of individual water-atomised tool steel particles in micrographs acquired in scanning electron microscopy. The micrographs of individual particles or their shape descriptors are then processed using and comparing two different strategies, namely linear regression or unsupervised machine learning (ML), to corelate the information collected on individual particles with the rheological properties of powder specimens. The approach developed aims to acquire new knowledge regarding specific particle characteristics that are required to optimise powder flowability for laser powder-bed fusion.

Particle mass flow determination in dust-laden supersonic flows by means of simultaneous application of optical measurement techniques

Particle mass flow rate and particle mass concentration are key parameters for describing two-phase flows, especially for particle-induced heating augmentation analysis. This work addresses the question of how accurate particle mass flow rate can be determined with three non-intrusive measurement approaches, based on shadowgraphy, particle tracking velocimetry (PTV), and scattered light intensity, in supersonic flows. In terms of shadowgraphy and PTV, the particle mass flow rate was determined by measuring individual particle characteristics, namely particle size, velocity, and density, as well as the measurement volume. The presented shadowgraphy procedure is based on the commercial LaVision DaVis software and additional shadowgraphy corrections. Multiple tests were conducted in the experimental test facility GBK of DLR with varying flow conditions, at a Mach number of 2.1, unit Reynolds number (Re∞) ranging from 5e7 1/m to 1.5e8 1/m, total temperature (T0) ranging from 303 to 544 K, and particle materials, namely Al2O3, MgO, and SiO2, in the size range of 1 to 60 µm. Particle size distributions of Al2O3 and MgO particles could be reproduced with shadowgraphy quite well, while the PTV procedure resulted in non-similar distributions. Pycnometer measurements indicated MgO particle density to be significantly lower than reference values. A DaVis parameter variation analysis resulted in a particle mass flow rate uncertainty of shadowgraphy of up to 30%. The particle mass flow rate uncertainty of PTV is approx. 76%, and the respective uncertainty of scaled PTV and scattered light intensity approach is 28%. The particle mass flow rate, measured with shadowgraphy, is 58% higher than those of the semi-axisymmetric scattered light intensity approach, which can be explained by a higher particle concentration at the injection plane.

Characteristics of Individual Particles for PM<sub>2.5</sub> Collected around Busan North Port

Characteristics of Individual Particles for PM<sub>2.5</sub> Collected around Busan North Port

Relationship between Atomic Force Microscopy and Centrifugation Measurements for Dust Fractions Implicated in Solar Panel Soiling.

This work tests the reliability of a simple, rapid centrifugal technique to estimate the removal force necessary to detach common airborne particles from the surface of a photovoltaic panel. Previously, we have used atomic force microscopy (AFM) to obtain the surface-particle adhesion force for different pollutant types that generally contribute to panel soiling. To overcome the limitations of AFM, the same particles were studied as a population using an ultracentrifuge. Detachment was quantified at speeds between 1000 and 10,000 rpm, both as individual particle counts and as projected surface area coverage. The force of centrifugal detachment for each particle type followed a similar trend as the adhesion force given by AFM. Organic and carbon-based materials needed higher centrifugal speeds to be removed, suggesting a stronger attachment to the surface. However, the technique also highlighted the importance of particle diameter, aggregates, and individual particle characteristics, which should be considered when predicting the probability of detachment. We have identified the relationship between AFM-derived adhesion and centrifugal detachment forces using model particle fractions of materials commonly found to soil solar panels, demonstrating the utility in using the more easily applied to centrifugal method to obtain information that can be calibrated to direct measurements of the force of particle attachment. This technique could be applied effectively in further studies on the influence of dust composition on long-term soiling and its reversibility.

Morphological and chemical classification of fine particles over the Yellow Sea during spring, 2015–2018

Airborne fine particles can affect climate change and human health; moreover, they can be transported over significant distances. However, studies on characteristics of individual particles and their morphology, elemental composition, aging processes, and spatial distribution after long-range transport over the Yellow Sea are limited. Therefore, in this study, we conducted shipborne measurements of fine particulate matter of less than 2.5 μm in diameter (PM2.5) over the Yellow Sea and classified the individual particles into seven types based on their morphology and composition. Overall, the percentage of organic-rich particles was the highest, followed by that of sea spray, sulfur-rich, dust, metals, fly ash, soot, and other particles. Near Shandong, China, the percentage of fly ash and sulfur-rich particles increased, while an increased percentage of only sulfur-rich particles was observed near the Korean Peninsula. In the open sea, the PM2.5 concentrations were the lowest, and sea spray particles predominated. During the cruises, three types (Types 1, 2, and 3) of events with substantially increased PM2.5 concentrations occurred, each with different dominant particles. Type 1 events frequently featured air masses from northern China and Mongolia with high wind speeds and increased dust particles. Type 2 events involved air masses from China with high wind speeds; fly ash, soot, organic-rich particles, and the sulfate percentage in PM2.5 increased. Type 3 events displayed stagnant conditions and local transport (from Korea); soot, dust particles, and the secondary sulfate and nitrate percentages in PM2.5 increased. Thus, different types of transport affected concentrations and dominant types of fine particles over the Yellow Sea during spring.

A review of atmospheric individual particle analyses: Methodologies and applications in environmental research

Aerosol ultra-fine and nano-particles are playing essential roles in the evolution of the Earth environment because of their deep connections to the chemical conversions and solar radiation energy transfer in the atmosphere, and have also become an urgent public concern in recent years due to their adverse health effects. Electron microscopes, as major tools being able to accurately identify the physical and chemical characteristics of individual particles in micron and submicron size, have been widely used in aerosol studies, although some barriers remain for their low efficiency and high cost. In this work, current understandings on the physical and chemical characteristics, mixing state and heterogeneous chemical reactions of individual aerosol particles, mainly obtained with electron microscopes, are reviewed. First, the techniques of individual particle analyses are briefly summarized and their advantages and disadvantages are discussed. Then, the morphology and composition of major atmospheric particle types obtained with these techniques and how the information was used to identify particle sources are introduced. The effects of aerosol particles on the environment, climate, human health, and global geochemical cycles are also discussed based on the data from individual particle analyses. Finally, challenges faced in individual particle studies are prospected.

Оцінка параметрів занурення частинок реагенту з газом у розплав при інжекційній позапічній десульфурації чавуну

The aim of the work is to develop a mathematical model for estimating the immersion of reagent particles with gas in molten iron during desulfurization. The technologies of out-of-furnace injection ladle desulfurization of cast iron are based on the introduction of reagent particles into liquid cast iron with the help of high-speed gas jets. The patterns of behavior and interactions of two-phase jets (carrying gas+reagent) with cast iron melt are complex, as the individual dynamic characteristics of individual particles are lost. Also important is the question of the ratio of the number of particles that went deep into the metal and the particles that ended up in the floating bubble. In the work, a number of experimental studies were performed to evaluate the factors and parameters of the immersion of the reagent particle during ladle desulfurization of cast iron. Experiments have shown that the depth of immersion of a reagent particle with a radius of 0.5 mm in the presence of a cavern depends on the velocity of the particle. For an initial speed of 20 m/s, the length of the cavern is about 6 gauges, and for a speed of 140 m/s - about 10 gauges. However, as it follows from the calculations, the velocities of the reactant particles drop rapidly, which should lead to a change in the flow structure and the emergence of caverns. In this case, capillary forces will play a significant role in the penetration of the reagent into the melt. In the developed model, they are taken into account as an additional factor. It is shown that these effects have a rather weak character compared to the repulsive force of Archimedes.

Dual-wavelength angle-resolved light scattering used in the analysis of particles by scanning flow cytometry

For the first time, a scanning flow cytometer (SFC) was applied for the analysis of individual particles using angle-resolved light scattering at two wavelengths simultaneously. The SFC was equipped with three lasers with wavelengths of 405, 444 and 660 nm. The performance of dual-wavelength angle-resolved light-scattering (DWARLS) flow cytometry was demonstrated by the analysis of polymer beads, spherized red blood cells (RBCs) and blood platelets. The main advantage of dual-wavelength flow cytometry relates to an increment in the precision of the inverse light-scattering problem solution. The solution allows one to retrieve the characteristics of individual particles by measuring the light-scattering profiles of these particles. DWARLS has allowed us to measure diameters and refractive indices (RIs) of polystyrene beads with record precision: a median error of 12 nm and a few thousandths for diameter and RI, respectively. Analysis of spherized RBCs with DWARLS flow cytometry has provided record precision in the sizing of spherized RBCs, with a median error of 16 nm for diameter, and an adequate value of the specific refraction increment for hemoglobin. By means of DWARLS, we have formed a numerical criterion for shape separation of blood platelets, which can be described by an oblate spheroid model to increase the precision of the distribution parameters of the platelet fractions.

Different characteristics of individual particles from light-duty diesel vehicle at the launching and idling state by AAC-SPAMS

The rapid development of cities and economic prosperity greatly motivates the growth of vehicular exhaust particles, especially the diesel-exhausted particles from the large fleet of passenger and freight, which present profound implications on climate, air quality, and biological health (e.g., pulmonary, autoimmune and cardiovascular diseases). As important physiochemical properties of atmospheric aerosols, however, the mixing state and effective density of individual particles emitted from diesel-powered vehicles under different driving conditions and their environmental implications remain uncertain. Here, a single-particle aerosol mass spectrometer (SPAMS) was used to investigate the chemical composition and vacuum aerodynamic diameter (Dva), along with the aerodynamic diameter (Da) from an aerodynamic aerosol classifier (AAC), to determine the effective density of primary particles emitted from a light- duty diesel vehicle (LDDV) under the launching and idling engine states. Interestingly, the particle types and effective density appear to vary significantly with the engine status. A single particle type of Ca-rich particles, named Na-Ca-PAH, was predominant in the idling state, whose chemical components may be affected by the lubricants and incomplete combustion, contributing to a higher effective density (0.66 ± 0.21 g cm−3). In contrast, launching particles exhibited a lower effective density (0.34 ± 0.17 g cm−3) because of the substantial elemental carbon (EC). In addition, the effective density depends not only on the particle size but also on the chemical components with various abundances. EC and Ca play opposite roles in the effective density of LDDV emissions. Notably, a higher proportion of polycyclic aromatic hydrocarbons (PAHs) was observed in the idling particles, contributing to 78 ± 1.2%. Given the high contribution to these PAH-containing particles in the idling state, indispensable precautions should be taken at bus stops or waiting for pedestrians. This study provides more comprehensive insights into the initial characteristics of LDDV particles due to the launching and idling states, which is beneficial for improving the model results of source apportionment and understanding its environmental behavior regarding human health.

Contact mechanics based solution to predict modulus of asphalt materials with high porosities

Asphalt mixtures with high porosities (known as porous asphalt (PA) mixes) are becoming a popular choice among road authorities as it provides better skid resistance while also reducing tire-pavement noises. Towards the design and manufacture of PA mix pavement, the evaluation of the mechanical properties of PA mixes is of great importance. To predict the mechanical properties of PA mixes, micromechanical models have been considered as an effective tool. In most research studies, continuum-based micromechanical models, i.e. the Self-consistent model, the Mori-Tanaka model, etc. are widely used to predict the stiffness of asphalt mixtures. However, the limitation of these models is that they cannot describe the characteristics of individual particles and thus they cannot provide accurate predictions. On the other hand, the discrete-based micromechanical model (DBMM) which simulates a granular material as an assembly of bonded particles seems to be a promising alternative. Limited research studies have focused on studying the utilization and the applicability of this model for asphalt mixes. Therefore, this paper aims to propose a framework to use DBMM and to evaluate its performance in estimating a PA mix’s stiffness. Based on the obtained results, both the merits and limitations of this model were highlighted.

Fine particles from village air in northern China in winter: Large contribution of primary organic aerosols from residential solid fuel burning.

Rural residential emissions contribute significantly to regional air pollution in China, but our understanding on how residential solid fuel burning influences the village outdoor air quality is limited. In this study, we compared the fine particulate matter (PM2.5) composition and individual particle characteristics from 11 to 18 January 2017at a village and an urban site in northern China. At the village site, each day was divided into four periods: cooking (07:30-10:00; 16:00-17:00), daytime (10:00-16:00), heating (17:00-24:00), and midnight (00:00-07:30) periods. The highest PM2.5 concentration occurred during the cooking period (236±88μgm-3), which was characterized by high concentrations of K+ and abundant primary OM-K particles (i.e., organic matter mixed with K-salts) emitted from residential biomass burning. The second highest PM2.5 concentration was found during the heating period (161±97μgm-3), and the PM2.5 contained abundant spherical primary OM particles (i.e., tarballs) emitted from residential coal burning. The primary emissions from residential solid fuel burning resulted in 75% of the village OM by mass consisting of primary OM and 67% of the village aerosol particles by number internally mixing with primary OM particles. The village PM2.5 composition was different from that of the urban PM2.5, with the former containing more OM (47% vs 32%) and less secondary inorganic ions (30% vs 46%). Individual primary OM-K and tarballs were abundant in the village air. These results suggest a large contribution of village residential emissions in the winter to village air pollution. Our study highlights that the residential health in villages of northern China should be paid more attention because of high PM2.5 concentrations and abundant toxic particles during the cooking and heating periods per day in winter.

Chemical mapping of tire and road wear particles for single particle analysis

Tire and road wear particles (TRWP), which are comprised of polymer-containing tread with pavement encrustations, are generated from friction between the tire and the road. Similar to environmentally dispersed microplastic particles (MP), the fate of TRWP depends on both the mass concentration as well as individual particle characteristics, such as particle diameter and density. The identification of an individual TRWP in environmental samples has been limited by inherent characteristics of black particles, which interfere with the spectroscopic techniques most often used in MP research. The purpose of this research was to apply suitable analytical techniques, including scanning electron microscopy coupled with energy dispersive X-ray spectroscopy (SEM/EDX) mapping and time-of-flight secondary ion mass spectrometry (ToF-SIMS) mapping, to characterize the specific physical and chemical properties of individual TRWP. Detailed elemental and organic surface maps were generated for numerous samples including bulk tread material, cryogenically milled tire tread particles, and TRWP generated from two separate road simulator methods. Key physical and chemical characteristics of TRWP for single particle identification included (1) elongated/round shape with variable amounts of mineral encrustation, (2) elemental surface characteristics including co-localization of (S + Zn/Na) ± (Si, K, Mg, Ca, and Al), and (3) co-localization of organic surface markers, such as C6H5+ and C7H7+. Comparisons of TRWP with other polymeric (polystyrene) and non-polymeric (carbon black) particle types demonstrated that a combination of physical and chemical markers is necessary to identify TRWP. Addition of a density separation step to the single particle analysis techniques allowed for the determination of average primary TRWP particle size (34 μm by number distribution and 49 μm by volume distribution) and aspect ratio (65% of TRWP with an aspect ratio > 1.5). The use of chemical mapping techniques, such as SEM/EDX and/or ToF-SIMS mapping as demonstrated herein, can support future research efforts that aim to identify complex MP.

Elemental composition of particles emitted from aircraft: High-sensitivity elemental analysis by using micro-PIXE

To achieve the elemental characterization of particles emitted from the aircraft, we performed elemental analysis using micro-PIXE for those emitted from carbon disc brakes and tires in addition to the turbine blade particles and engine reverser particles of the exhaust produced by jet engines, and identified the characteristics of individual particles from the elemental maps. As for the elemental characteristics of aircraft source particles, the turbine blade particles contained 16 elements (Na, Mg, Al, Si, S, K, Ca, Se, Ti, Cr, Mn, Fe, Co, Ni, Cu and W), and were considered to be those of the same origin. In the case of the engine reverser particles, in addition to turbine blade particles and turbine blade wear particles (nickel alloy), atmospheric particles were found. As one hypothesis, particles containing Ti–V, Mn–W and Cu–Zn may have got altered or aggregated in the process of particles moving from the turbine blade to the engine reverser. Clumps of particles were exhibited only in the elemental maps of tire particles. These clumps of particles were shaped like they had been scraped away, and were believed to have been caused by friction between the tire and the runway. These results aid in determining the component features of particles emitted from an aircraft.

Individual Particle Characteristics, Optical Properties and Evolution of an Extreme Long‐Range Transported Biomass Burning Event in the European Arctic (Ny‐Ålesund, Svalbard Islands)

AbstractThis paper reports an exceptional biomass burning (BB) advection event from Alaska registered at Ny‐Ålesund from 10 to 17 July 2015 with particular interest on the influence of the airborne particle characteristics on the optical properties of the aerosol during the event. To this purpose we considered two DEKATI 12‐stage aerosol samples spanning the entire advection and analyzed them by scanning electron microscopy techniques. Aerosol chemical data and microphysical properties were also evaluated in order to correlate any change of individual particle characteristics with the bulk properties of the aerosol. The results of individual particle analysis depict a complex event characterized by a first phase (P1) of massive input of BB carbonaceous particles (i.e., tar balls, popcorn refractory particles, and organic particles), and by a second phase (P2) dominated by inorganic salts. The peculiar feature of this BB event is the exceptionally large grain size of the subspherical organic particles at the beginning of the event with respect to the background. At these conditions a significant increase of the scattering efficiency may occur even for a small increase of the size parameter. Results of the simulation of the complex refractive indices (n‐ik) confirm this evaluation. Aerosol evolution during the event resulted from the combination of three distinct occurrences: (a) progressive rotation of air mass circulation toward non‐BB source areas, (b) development of a thick fog layer in the planetary boundary layer, and (c) sea salt spray direct advection of local/regional provenance.

Morphology and size of the particles emitted from a gasoline-direct-injection-engine vehicle and their ageing in an environmental chamber

Abstract. Air pollution is particularly severe in developing megacities, such as Beijing, where vehicles equipped with modern gasoline-direct-injection (GDI) engines are becoming one of major sources of the pollution. This study presents the characteristics of individual particles emitted by a GDI vehicle and their ageing in a smog chamber under the Beijing urban environment, as part of the Atmospheric Pollution & Human Health (APHH) research programme. Using transmission electron microscopy, we identified the particles emitted from a commercial GDI-engine vehicle running under various conditions, namely cold-start, hot-start, hot stabilized running, idle, and acceleration states. Our results showed that most of the particles were organic, soot, and Ca-rich ones, with small quantities of S-rich and metal-containing particles. In terms of particle size, the particles exhibited a bimodal distribution in number vs size, with one mode at 800–900 nm and the other at 140–240 nm. The numbers of organic particles emitted under hot-start and hot stabilized states were higher than those emitted under other conditions. The number of soot particles was higher under cold-start and acceleration states. Under the idle state, the proportion of Ca-rich particles was highest, although their absolute number was low. In addition to quantifying the types of particles emitted by the engine, we studied the ageing of the particles during 3.5 h of photochemical oxidation in an environmental chamber under the Beijing urban environment. Ageing transformed soot particles into core–shell structures, coated by secondary organic species, while the content of sulfur in Ca-rich and organic particles increased. Overall, the majority of particles from GDI-engine vehicles were organic and soot particles with submicron or nanometric size. The particles were highly reactive; they reacted in the atmosphere and changed their morphology and composition within hours via catalysed acidification that involved gaseous pollutants at high pollution levels in Beijing.Highlights. GDI-engine vehicles emitted a large amount of both primary and secondary organic aerosol (SOA). Higher numbers of organic particles were emitted under hot stabilized running and hot-start states. Sulfate and secondary organic aerosol formed on the surface of primary particles after ageing. Particles aged rapidly by catalysed acidification under high pollution levels in Beijing.

Charge Carrier Dynamics in Sr-Doped NaTaO3 Photocatalysts Revealed by Deep Ultraviolet Single-Particle Microspectroscopy

Among various metal oxides, sodium tantalate (NaTaO3) is one of the best semiconductors for achieving efficient photocatalytic water splitting. However, the primary mechanism responsible for increasing the reaction rate up to an order of magnitude by specific metal doping and surface modification with co-catalysts has not been elucidated yet. In order to clarify the underlying mechanism, we explored the structure-dependent photoluminescence (PL) of pristine and Sr-doped NaTaO3 crystals at the (near) single-particle level using a time-resolved deep ultraviolet fluorescence microscope. Combined with transmission electron microscope techniques, the PL characteristics of individual particles were directly linked to the dopant concentrations in each particle, allowing us to unravel the complex effects of Sr-doping on the charge carrier dynamics. Furthermore, we investigated the photocatalytic reduction reaction for a single Sr-doped NaTaO3 particle to gain critical information related to dopant-driven electron...

Characteristics of Individual Particles Emitted from an Experimental Burning Chamber with Coal from the Lung Cancer Area of Xuanwei, China

ABSTRACT Pollutants emitted from household coal burning in Xuanwei, China, have been recognized as the reason for the high lung cancer mortality and morbidity rates in the area. To examine the characteristics of particles emitted from coal burning, a coal burning-dilution chamber was designed, and the individual particles emitted from the chamber at different burning stages were collected. The morphologies and elemental compositions of the individual particles were analyzed by high resolution transmission electron microscopy. Four types of particles, namely, organic particles, soot particles, S-rich particles, and mineral particles, were identified. The largest percentage of particles by number in the ignition stage, fierce-burning stage, and char-burning stage was composed of organic particles (66%), soot particles (71%), and mineral particles (73%), respectively. A distinctive characteristic was the remarkable abundance of Si- and Fe-rich particles during the char burning stage, compared with emissions from other types of coal. According to the elemental composition, 49% of the mineral particles were Si-rich, 25% were Ca-rich, 14% were Fe-rich, and 7% were Ti-rich. The Si-rich particles were partly identified as quartz (SiO2), the Ca-rich particles were found to be CaSO4 or CaCO3, the Fe-rich particles were primarily Fe2O3 or Fe3O4, and the Ti-rich particles were mainly TiO2. Notably, SiO2 is a human carcinogen, and Fe-rich particles possess a high reactive potential with DNA-markers.

Diazotrophs and N2-Fixation Associated With Particles in Coastal Estuarine Waters.

Putative heterotrophic bacteria carrying out N2-fixation, so-called non-cyanobacterial diazotrophs (NCDs), are widely distributed in marine waters, but details of how the O2-inhibited N2-fixation process is promoted in the oxic water column remains ambiguous. Here we carried out two experiments with water from a eutrophic temperate fjord to examine whether low-oxygen microenvironments within particulate organic matter could be loci suitable for N2-fixation. First, water enriched with natural particles or sediment showed higher N2-fixation rates than bulk water, and nitrogenase genes (nifH) revealed that specific diazotrophs were affiliated with the particulate matter. Second, pristine artificial surfaces were rapidly colonized by diverse bacteria, while putative diazotrophs emerged relatively late (after 80 h) during the colonization, and phylotypes related to Pseudomonas and to anaerobic bacteria became dominant with time. Our study pinpoints natural particles as sites of N2-fixation, and indicates that resuspension of sediment material can elevate pelagic N2-fixation. Moreover, we show that diverse natural diazotrophs can colonize artificial surfaces, but colonization by “pioneer” bacterioplankton that more rapidly associate with surfaces appears to be a prerequisite. Whereas our experimental study supports the idea of pelagic particles as sites of N2-fixation by heterotrophic bacteria, future in situ studies are needed in order to establish identity, activity and ecology of particle associated NCDs as a function of individual particle characteristics.

The effect of temperature on the mechanical characteristics of individual particles

The current work investigates the effect of temperature on the mechanical characteristics such as breakage force, breakage energy, yield force and effective modulus of elasticity of individual particles. This is important for modeling particle attrition at different temperature conditions. The results were obtained by employing uniaxial compression tests at different temperatures between 210 and 465 K. Besides giving results and analysis, this paper provides in detail unique particle's heating and cooling chambers specially designed for this topic and allows keeping particle temperature constant through the entire experiment process. Seven various particulate materials tested during this study: dead-sea salt and potash, GNP, silica gel, zeolite 4A, alumina and novolen 1040n particles, with different fraction sizes ranging 0.71 ÷ 5 mm. The results showed that the strengths of salt and silica gel particles increase with the temperature. Therefore, more energy is required in order to break these particles at high temperatures. Effective modulus of elasticity for most of the materials reduced at high temperatures confirming the particles become softer. Consequently, empirical models were proposed describing the distribution of the breakage force, breakage energy, yield force and effective modulus of elasticity versus the particle size and temperature.