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Primary goal of this article is to present recent developments in erosion research and associated particles in centrifugal slurry pumps. Solid particles in transported liquid cause severe erosion of components in centrifugal pumps causing poor performance and reduced lifespan. Erosion necessitates frequent repairs and maintenance replacements, resulting in significant financial losses. This article summarizes the effect of slurry erosion on the performance characteristics of centrifugal pumps handling different fluid and solid mixtures, as well as methods to reduce erosion. According to the majority of the literature, particle properties, pump geometry, and operating parameters have a paramount influence on pump characteristics. Recently, researchers attempted to improve the performance characteristics of centrifugal pumps by employing various flow visualization techniques, which also aid in understanding the solid particle interaction with various pump components. Therefore, recent advancements in flow visualization technology inside the centrifugal pump are also included. Further, specific studies on erosion in centrifugal slurry pumps from different industries are also provided. This study is beneficial to designers, process managers and researchers involved with slurry centrifugal pumps. [ABSTRACT FROM AUTHOR]

Diesel Oxidation Catalyst (DOC) is the most important and advanced part of the after-treatment technology route. After the exhaust passes through DOC, CO, and HC will be significantly reduced, while particles are mainly captured by the Diesel Particulate Filter (DPF) device behind. In order to further investigate the effect of DOC on the nano-structure characteristics of diesel emission particles. The particles before and after DOC of 186FA diesel engine at 2700 r/min, 100% load, and 3600 r/min, 100% load are collected. The nano-structure characteristics of particles are investigated using field emission transmission electron microscopy (FETEM) combined with small angle X-ray scattering radiation technique (SAXS). Based on FETEM and SAXS analysis of particles, a nano-scale particle spatial structure model including particle size, pores, and visual boundary layer is proposed. The results show that the average radius, interface layer thickness, and fractal dimension of the particles are reduced after the DOC. In contrast, the specific surface area of the particles is increased after the DOC. At 3600 r/min 100% load, the average radius is reduced from 23.3 to 21.5 nm, accounting for 7.8%. Interface layer thickness is reduced from 13.3 to 12.9 nm. The specific surface area of the particles is increased from 0.146 to 0.166 m² /mm³ . The research results provide a theoretical basis for the regeneration and oxidation of particles in DPF. [ABSTRACT FROM AUTHOR]

To improve the wear resistance of the centrifugal slurry pump, the inlet structure is optimized, and an equal-diameter inlet section structure is designed. Considering the particle-particle and particle-wall interactions, a two-phase flow simulation model based on CFD-DEM (computational fluid dynamics-discrete element method) coupling is established under the sparse particle condition. The Archard wear model and Relative wear model are used for quantitative and qualitative wear analysis. The flow field and particle trajectory analysis are carried out under an equal-diameter inlet section structure and a different-diameter inlet section structure. The wear characteristics of the flow-passing parts are carried out. The results show that the simulation model has good accuracy. The error between the numerical simulation results and the experimental results is less than 5%. Under the equal-diameter inlet section structure, the overall wear of the slurry pump is reduced by 15%, the wear of the volute chamber is reduced by 17.5%, and the wear of the inlet section is reduced by 93.8%. The equal-diameter inlet section structure can reduce the turbulent intensity and make the flow field stable. And the equal-diameter inlet section structure helps to reduce the wear degree and wear area of the pump. [ABSTRACT FROM AUTHOR]

Natural fiber composites are a potential material in a range of engineering applications because of their excellent properties, which include reduced weight, better strength, and economic affordability. Aside from these features, these materials are biodegradable and renewable. The intent of this study is to look through into mechanical properties of aluminum oxide (Al2 O3), boron carbide (B4C), and silicon carbide (SiC) particle-filled jute fiber polymer composite. The response surface methodology (RSM) with three levels/three factors is used to achieve the different combinations of process variables required to fabricate the desired polymer composites. In this regard, the effect of process variables on tensile characteristics, increase in weight %, and flexural characteristics is examined in detail. Further, the best combination of process parameters is chosen to produce composites with the desired mechanical qualities. The significance of such variables on each output variable is assessed using analysis of variance. A hybrid grey-based adaptive neuro-fuzzy inference system model is constructed for establishing multiple performance indexes. From the validation outcomes obtained, it is proved that the evolved model is proficient for precise prediction. [ABSTRACT FROM AUTHOR]

An exploratory study was performed to determine the distribution of surgical smoke particulate matter (SSPM) and evacuation times within an AirSeal® System and a traditional insufflation access system in various simulated surgical scenarios. Identified trends showed statistical significance when setting the AirSeal® System to Low smoke evacuation that it reduces the percentage of particulate matter at the Access Port opening. Additionally, it was observed that when utilising a laparoscopic tool a similar trend in particle distributions were seen between either insufflation and access system at the opening of the Access Port and trocar. Evacuation times for SSPM removal within the AirSeal® System showed an overall average to ≥95% reduction of 5.64 min within the surgical cavity, 3.69 min at the Access Port opening, and 3.61 min within the smoke evacuation line. The overall average for the traditional insufflation and access system was 9.38 min within the surgical cavity and 6.06 min at the trocar opening. Results showed that when using the traditional system compared to the AirSeal® System, it resulted in a percent change increase in evacuation times of 66.31% within the surgical cavity and 64.23% at the trocar opening. [ABSTRACT FROM AUTHOR]

In this paper, cyclone separator is proposed for the first time to separate particles according to density, and it is applied to the recovery of lithium iron phosphate (LFP) from spent lithium battery materials for the first time. The effect of the flow field on the motion of injected particles in a cyclone separator is studied by means of computational fluid dynamics (CFD). It is found that there is a classification phenomenon caused by the difference in the particle densities and the separation process is simulated accordingly. The results show that 60% LiFePO4 in the original feed can be separated after 7 separations, and the mass purity is 91%, with 7% Al and 2% Fe under instantaneous surface injection conditions. Compared with the original feed, LFP is effectively recycled. After 15 separations, the efficiency increases to 76%. Under simulated continuous injection conditions, the separation efficiency of LFP is 61.22% after 20 simulated separations, and the mass purities of the separated products are 92.53% LFP, 6.92% Al, 0.44% Fe and 0.11% Cu. Compared with the traditional method, the new method has advantages of low energy consumption, low cost, theoretically no pollution, and great development potential. [ABSTRACT FROM AUTHOR]

The recovery of coal particles in a flotation column was investigated to determine its dependency on the type of frother, particle size, and gas and feed velocities. The kinetics of the cumulative recovery was established. The induction time and flotation rate constant were analyzed based on the recovery, incorporating the stability, attachment, and collision efficiencies of the particles with the bubbles. An inverse relationship between recovery and induction time was observed. Recovery of the particles was noticed to increase with superficial air velocity and frother dose, while it decreased with increasing particle size and feed circulation velocity. The induction time decreases with increasing superficial air velocity and frother dose but increases with increasing particle size and feed circulation velocity. Low induction time and high recovery were observed in the cationic frother. Small particles with low induction time can be captured with ease and have excellent selectivity. A generalized correlation for the induction time was proposed based on experiments under different operating conditions. The presented research will be beneficial in terms of increasing the transport efficiency of flotation systems. [ABSTRACT FROM AUTHOR]

This study's aim was to determine the presence, as well as to evaluate the health and environmental impacts, of chemical elements from firearm shots during shooter practice at outdoor shooting ranges, both in the environment and on the shooters' hands. Two high-precision devices were used for measuring suspended particles that are released during discharge of Taurus PT 100.40 caliber pistols. The analysis of collected data allowed the identification of specific distribution patterns of samples that were adsorbed. Moreover, samples were collected from the opisthenar area of the hand to investigate both the occurrence and deposition of particles and chemical elements through scanning electron microscopy coupled with energy dispersive spectroscopy (SEM-EDS). The results indicate that copper, lead, and zinc concentration profiles will be able to delimit and reveal more precise details regarding shots made with nontoxic ammunition (NTA). In particular, the residual graphic analysis indicated that the majority of metal deposited in the shooter's hand is zinc. Further, the metals barium and lead also were detected. Due to the exposure to these elements, it could be concluded that engineering controls and administrative management should be sought in order to avoid human overexposure and environmental release of these airborne toxic metals. [ABSTRACT FROM AUTHOR]

Electrospraying technique has attracted much attention in food science because of its importance for biological macromolecule encapsulation of food bioactive substances. The purpose of this review is to overview the electrospraying technique and its recent application advances for biological macromolecule encapsulation of food bioactive substances. First, the history, principles, setup, and products of the electrospraying technique are briefly introduced. Second, the application of electrosprayed nano-, micro-, and millimeter-sized particles with solid, porous, core-shell, and multi-core structures for biological macromolecule encapsulation of nutrients is reviewed. Thirdly, the application of electrosprayed micro- and millimeter-sized particles for biological macromolecule encapsulation of probiotics is analyzed. Finally, the application of electrospraying technique for biological macromolecule encapsulation of food bioactive substances is summarized and an outlook is provided. This review will provide guide instruction to the research and development of electrosprayed particles for biological macromolecule encapsulation of food bioactive substances in novel food development. It will be useful for those who are interested to enter this field. [ABSTRACT FROM AUTHOR]

The sphericity and size of ammonium perchlorate (AP) particles are the most significant properties in composite propellants. In this study, using the Taguchi method, the effects of surfactant type, surfactant concentration, stirring speed, cooling rate, and AP concentration parameters were investigated on the sphericity and size of AP particles in the cooling crystallization process (CCP). The sphericity and size of AP particles were calculated from the scanning electron microscopy (SEM) images by microstructure image processing (MIP) technique. The results showed that the selected parameters have sufficient effect on the sphericity and size of AP particles, based on analysis of variance. In this regards, the most effective parameters for sphericity and size optimization are the stirring speed and the surfactant type, respectively. Also, the AP concentration had the least effect on the sphericity and size of AP particles. Based on analysis of variance; the optimum sphericity and size equal to 0.84 and 21 μm, were predicted in CCP for AP particles, separately. Then, the particle sphericity of 0.84 and size of 23 μm was obtained from the suggested experimental optimal conditions. The differences between the predicted and experimental results are 1.7 and 8% for sphericity and size of AP particles, respectively. [ABSTRACT FROM AUTHOR]

Porous Si100-xSnx samples with x = 15, 30 and 40 at.% were produced from Si and Sn elemental powders by mechanical alloying followed by two different compaction and sintering processes: cold uniaxial pressure and subsequent sintering at 220°C, and hot pressing at 240°C. The results showed that it is possible to produce samples with a major porosity of close to 0.1 μm. The porosity of the Si70Sn30 sample that was mechanically alloyed for 12 h and synthesized by the former process is in the mesoporous region. The structure of all the final samples is composed of the Si, Sn and SnO phases. [ABSTRACT FROM AUTHOR]

Laser-induced breakdown spectroscopy (LIBS) is a rapid and simple analytical method that provides qualitative and quantitative elemental information of samples without damaging them and does not require any sample preparation. Recently, an increasing number of studies have used LIBS to detect aerosols. This technique meets the requirements to be used in some practical applications, such as atmospheric monitoring and industrial processes. However, the unique properties of aerosols bring a level of uncertainty to the LIBS signals of the samples, which is an obstacle to overcome. This review attempts to summarize the relevant research regarding aerosol-LIBS, including the various apparatuses, conditional analysis methods, effects of plasma–particle interactions, means for improving signal intensity, and applications. [ABSTRACT FROM AUTHOR]

Thousands of abandoned uranium mines (AUMs) exist in the western United States. Due to improper remediation, windblown dusts generated from AUMs are of significant community concern. A mobile inhalation lab was sited near an AUM of high community concern ("Claim 28") with three primary objectives: to (1) determine the composition of the regional ambient particulate matter (PM), (2) assess meteorological characteristics (wind speed and direction), and (3) assess immunological and physiological responses of mice after exposures to concentrated ambient PM (or CAPs). C57BL/6 and apolipoprotein E-null (ApoE−/-) mice were exposed to CAPs in AirCARE1 located approximately 1 km to the SW of Claim 28, for 1 or 28 days for 4 hr/day at approximately 80 µg/m3 CAPs. Bronchoalveolar lavage fluid (BALF) analysis revealed a significant influx of neutrophils after a single-day exposure in C57BL/6 mice (average PM2.5 concentration = 68 µg/m3). Lungs from mice exposed for 1 day exhibited modest increases in Tnfa and Tgfb mRNA levels in the CAPs exposure group compared to filtered air (FA). Lungs from mice exposed for 28 days exhibited reduced Tgfb (C57BL/6) and Tnfa (ApoE−/-) mRNA levels. Wind direction was typically moving from SW to NE (away from the community) and, while detectable in all samples, uranium concentrations in the PM2.5 fraction were not markedly different from published-reported values. Overall, exposure to CAPs in the region of the Blue GAP Tachee's Claim-28 uranium mine demonstrated little evidence of overt pulmonary injury or inflammation or ambient air contamination attributed to uranium or vanadium. [ABSTRACT FROM AUTHOR]

In the defense industry, UHMWPE is primarily used as ballistic material because of its light weight, superior mechanical properties, and particularly, its excellent strength-to-weight ratio compared to metal alloys. In this study, the influence of the AWJ process parameters on machining UHMWPE material is investigated. Several UHMWPE plates have been prepared for trimming, pocketing, and hole making experiments using AWJ to understand the process parameter effects on performance measures. The design of experiment method has been used for all experiments and results are analyzed by the analysis of variance and response surface methods. Furthermore, a novel evolutionary optimization method known as particle swarm optimization has been applied to determine trade-offs between the conflicting performance measures of surface roughness and dimensional error in AWJ. With the resulting Pareto optimal solution curve, three industrial scenarios have been developed using k-means clustering algorithm and verified. [ABSTRACT FROM AUTHOR]

Quantifying the relative bioavailability of particles versus ions is a key step toward understanding the mechanisms of bioaccumulation and toxicity of silver nanoparticles (AgNPs). Here we investigated AgNP uptake kinetics by wheat Triticum aestivum L. at different ages (i.e. 15- and 30-day after germination) in hydroponics. The concentration-dependent accumulation of AgNPs under the experimental conditions, in which AgNP dissolution in bulk suspension and at the biological interface was ruled out, confirmed the direct uptake of particles. This was further validated by the detection of Ag-containing particles within plants by single particle inductively coupled plasma mass spectrometry. Plants differentiated particles and dissolved ions, with uptake rate constants of particles and dissolved ions 4.3 ± 0.6 to 5.2 ± 0.6 and 288.6 ± 13.4 to 450.6 ± 63.4 L kg−1 h−1, respectively. Plant age appeared to have a negligible influence on uptake rate constant ratio of particles to ions. As a result, the relative contribution of particulate uptake to overall AgNP accumulation varied as a function of AgNP dissolution in nature. Particulate uptake was dominant when the dissolution was less than 1.2%. These findings help clearing up the inconsistency of uptake mechanisms of AgNPs in literature and could be used to predict their environmental impact and significance. [ABSTRACT FROM AUTHOR]

The Ultrasonic Personal Aerosol Sampler (UPAS) is a small, lightweight, and quiet sampler that collects airborne particulate matter on a filter for gravimetric or compositional analysis. The objective of this work was to develop UPAS inlets with collection efficiencies that match criteria for respirable or thoracic mass sampling. The two-stage inlet for respirable mass described here utilizes an impaction stage and a cyclone, whereas the one-stage inlet for thoracic mass sampling utilizes a circular slot impactor. Inlet designs are based on particle collection theory used in conjunction with an optimization algorithm to predict initial inlet dimensions; these predictions were the starting points for experiments that finalized dimensions and operating conditions. Both the respirable mass inlet and the thoracic mass inlet described here are interchangeable with the UPAS, and both have efficiencies that match well with their respective standards. With either inlet, the collected sample should be within ±5% of what the standard specifies for aerosols with reasonably broad size distributions. [ABSTRACT FROM AUTHOR]

Objective: The lungs are uniquely exposed to the external environment. Sand and dust exposures in desert regions are common among deployed soldiers. A significant number of Veterans deployed to the Middle East report development of respiratory disorders and diseases. Materials and methods: Sand collected from Fallujah, Iraq and Kandahar, Afghanistan combat zones was analyzed and compared to a sand sample collected from an historic United States (U.S.) battle region (Fort Johnson, James Island, SC, Civil War battle site). Sand samples were analyzed to determine the physical and elemental characteristics that may have the potential to contribute to development of respiratory disease. Results: Using complementary scanning electron microscopy (SEM) imaging and analysis, and inductively coupled plasma mass spectrometry (ICP-MS), it was determined that Iraq sand contained elevated levels of calcium and first row transition metals versus Afghanistan and U.S. sand. Iraq sand particle texture was smooth and round, and particles were considerably smaller than Afghanistan sand. Afghanistan sand was elevated in rare earth metals versus Iraq or U.S. sands and had sharp edge features and larger particle size than Iraq sand. Conclusions: These data demonstrate significant differences in Iraq and Afghanistan sand particle size and characteristics. Middle East sands contained elevated levels of elements that have been associated with respiratory disease versus control site sand, suggesting the potential of sand/dust storm exposure to promote adverse respiratory symptoms. Data also demonstrate the potential for variation based on geographical region or site of exposure. The data generated provide baseline information that will be valuable in designing future exposure studies. [ABSTRACT FROM AUTHOR]

Four kinds of tested fuels were prepared by adding Fe fuel-borne catalyst (Fe-FBC) to diesel at mass concentrations of 0, 100, 200 and 300 mg/kg, named as Diesel, Fe100, Fe200 and Fe300, respectively. Effects of discharge voltage on particle charge characteristic of diesel exhaust were carried out on a bipolar charge agglomeration test bench. Engine exhaust particle sizer and Zeta potential analyser were used to study the particle number concentration and surface electrical charge. The results show that the particle diameter of the peak number concentration becomes smaller with the increase of Fe-FBC content. Based on electrical charge agglomeration, particle coagulation efficiency increases with the increase of discharge voltage and Fe-FBC content, and particle number concentration of Fe300 has the greatest reduction. Besides, both Zeta potential and particle-surface charge increase with the increment of discharge voltage, and particles of Fe300 have the best charging performance among all tested fuels. [ABSTRACT FROM AUTHOR]

Aiming at the problem of natural gas hydrate blockage inside oil and gas pipelines, the key to reasonably suppress the formation of hydrates in pipelines is to find the factors that cause the hydrates to coalesce quickly. Since carbonates and silicon-containing substances are the main components of impurities in mining, the formation of methane hydrate has been studied. The emulsion was formulated with Span85 and SDS, and the formation rate and growth morphology of the hydrate were studied by adding nano-calcium carbonate. Experiments were carried out on emulsion systems having a particle content ranging from 0.1 wt% to 6 wt%. The results show that when the particle content in the system is low (less than 0.3 wt%), the hydrate formation rate is accelerated; when the particle content is high (above 2 wt%), the hydrate formation rate is lowered. This phenomenon was confirmed by calculating the moles consumption of methane gas. Moreover, the particles increase the collision probability of the crystal nucleus in the system, and can be used as a nucleation site of the hydrate crystal nucleus. The promotion or inhibition of the system on hydrate growth has reference value for preventing pipeline blockage. [ABSTRACT FROM AUTHOR]

Knowledge of particle deposition and transport in saturated porous media is of significant importance for various engineered applications and environmental concerns. Surface physical and chemical heterogeneities play a critical role in particle deposition because they can increase attachment in the primary minima of Derjaguin-Landau-Verwey-Overbeek (DLVO) interaction energy profile by reducing the repulsive energy barrier. We present a comprehensive review showing that surface heterogeneity can alter particle deposition through multiple additional mechanisms such as increasing attachment at secondary minima at concave locations and detachment from primary minima at nanoscale convex asperities. The pore-scale deposition mechanisms due to surface heterogeneity can cause anomalous particle retention and transport behaviors at continuum scales such as equilibrium sorption and nonmonotonic retention profiles. To accurately determine the particle transport in porous media at continuum scales requires future research: (1) improving existing techniques to accurately measure and represent surface heterogeneities and determine attachment and detachment; (2) using statistic models to characterize variations of attachment and detachment with surface heterogeneity; (3) using Lagrangian/Eulerian approach to thoroughly understand pore-scale retention mechanisms in porous media, and incorporating them into continuum equations to simulate particle transport at continuum scales. [ABSTRACT FROM AUTHOR]

In oil and gas exploitation and pipeline transportation, hydrate formation poses a significant hidden danger to pipeline safety. Hydrates in the pipelines can coalesce easily on the inner wall surface. Therefore, studying the growth characteristics of hydrates in a multicomponent environment is crucial pipeline anti-blocking technology. Hence, two types of white oil emulsion, S85 + T20 and S85 + SDS, were prepared using sorbitol three oleic acid ester, polyoxyethylene sorbitol monoanhydride, and sodium dodecyl sulfate as dispersants. The mechanism of methane hydrate blockage in emulsion and particle systems at 40% moisture content was analyzed. The hydration reaction induction time and phenomenon characteristics of the two were compared, and the effect of the first 30 min particle size change on the hydration reaction was observed by focused beam reflectance measurement. The experimental results indicate that adding particles to the S85 + SDS emulsion system can shorten the time of hydration reaction dissolved gas significantly, while the hydrophilic particle system will reduce the droplet size at a certain concentration, inhibit the heat transfer and mass transfer between molecules, and prolong the induction of hydrate formation. [ABSTRACT FROM AUTHOR]

This paper presents the effects of cutting speed, nanoparticles' size, and their concentration in water-based TiO2 nanofluid on the magnitude of tool flank wear and tool wear rate. The types of nanoparticles and base fluid, nanoparticle size, and nanoparticle concentration can affect the tribological and heat transfer properties of nanofluids, and thereupon, these parameters can affect the cutting forces and temperatures during the metal cutting process, thereby affecting tool wear and nanolubricant consumption. According to the achieved results, with an increase in the size of nanoparticles from 10 to 50 nm, the average decrease in cutting tool flank wear reduces from 46.2% to 34.8%. [ABSTRACT FROM AUTHOR]

The aim of this study was to measure the concentrations of gaseous and particulate contaminants originated from additive manufacturing operations and post-processes in an occupational setting when plastics were used as feedstock materials. Secondary aims were to evaluate the concentration levels based on proposed exposure limits and target values and to propose means to reduce exposure to contaminants released in additive manufacturing processes. Volatile organic compounds were sampled with Tenax TA adsorption tubes and analyzed with a thermo desorption gas chromatography-mass spectrometry instrument. Carbonyl compounds were sampled with DNPH-Silica cartridges and analyzed with a high-performance liquid chromatography device. Particles were measured with P-Trak instrument and indoor air quality was sampled with IAQ-Calc instrument. Dust mass concentrations were measured simultaneously with a DustTrak DRX instrument and IOM-samplers. Particle concentrations were highest (2070-81 890 #/cm3 mean) during manufacturing with methods where plastics were thermally processed. Total volatile organic compounds concentrations, in contrast, were low (113–317 µg/m3 mean) during manufacturing with such methods, and vat photopolymerization. However, total volatile organic compounds concentrations of material jetting and multi jet fusion methods were higher (1,114–2,496 µg/m3 mean), perhaps because of material and binder spraying, where part of the spray can become aerosolized. Chemical treatment of manufactured objects was found to be a severe volatile organic compounds source as well. Formaldehyde was detected in low concentrations (3–40 µg/m3) in all methods except for material jetting method, in addition to several other carbonyl compounds. Notable dust concentrations (1.4–9.1 mg/m3) were detected only during post-processing of powder bed fusion and multi jet fusion manufactured objects. Indoor air quality parameters were not found to be notably impacted by manufacturing operations. Only low concentrations (below 2 ppm) of CO were detected during several manufacturing processes. All studied additive manufacturing operations emitted potentially harmful contaminants into their environments, which should be considered in occupational additive manufacturing and workplace design. According to the measured contaminant levels it is possible that adverse additive manufacturing related health effects may occur among exposed workers. [ABSTRACT FROM AUTHOR]

Computational modeling together with experimental data are essential to assess the risk for particulate matter mediated lung toxicity and to predict the efficacy, safety and fate of aerosolized drug molecules used in inhalation therapy. In silico models are widely used to understand the deposition, distribution, and clearance of inhaled particles and aerosols in the human lung. Exacerbations of chronic obstructive pulmonary disease (COPD) have been reported due to increased particulate matter related air pollution episodes. Considering the profound functional, anatomical and structural changes occurring in COPD lungs, the relevance of the existing in silico models for mimicking diseased lungs warrants reevaluation. Currently available computational modeling tools were developed for the healthy adult (male) lung. Here, we analyze the major alterations occurring in the airway structure, anatomy and pulmonary function in the COPD lung, as compared to the healthy lung. We also scrutinize the various physiological and particle characteristics that influence particle deposition, distribution and clearance in the lung. The aim of this review is to evaluate the availability of the fundamental knowledge and data required for modeling particle deposition in a COPD lung departing from the existing healthy lung models. The extent to which COPD pathophysiology may affect aerosol deposition depends on the relative contribution of several factors such as altered lung structure and function, bronchoconstriction, emphysema, loss of elastic recoil, altered breathing pattern and altered liquid volumes that warrant consideration while developing physiologically relevant in silico models. [ABSTRACT FROM AUTHOR]

The technologies for analysis of wastewater contaminants have recently experienced rapid advancement. One of these technologies, with high potential in wastewater treatment is the analysis of the particle size distribution (PSD) of contaminants. However, there are no detailed documented studies on the application of this technique. This study aimed at critically reviewing the technologies for PSD analysis and the application of chemical oxygen demand (COD) fractionation analysis for the characterisation of municipal wastewaters. The suitability of the PSD technology for wastewater depends on the type of wastewater and its treatment process applied. Despite the advancements in PSD technologies, many researchers and industrialists are yet to utilise PSD analysis for wastewater. It is possible to use PSD to map out the foulants distribution for optimal design of membrane treatment of municipal and other wastewaters. Biological processes increase colloidal particles which are predominantly responsible for membrane fouling. There should be more investigations on how different wastewater treatment processes alter the PSD of contaminants. More usage of PSD analysis will lead to faster and more optimal designs of the treatment processes for the removal of contaminants. It will also have great usage in the process design for the recovery of useful products from the wastewaters. [ABSTRACT FROM AUTHOR]

Poly(dimethylsiloxane) (PDMS) has been widely used for prototyping of chips. Among many kinds of microstructures, it is almost impossible to make few micron-sized PDMS particles through microfluidic focusing methods because of the highly viscous property of uncured PDMS. Vigorous mixing of PDMS with water resulted in small, spherical particles was found. Furthermore, a simple and easy method was devised to assure an emulsion state. The PDMS-water emulsion was made using two syringes connected by a needle. This emulsion was rapidly heated to cure the PDMS within the emulsion. The resultant PDMS was examined using spectroscopic methods to determine the particulate morphology and size distribution. PDMS particles of which the size was around 1 µm with a narrow size distribution was produced. DNA delivery into cultured animal cells through these PDMS microparticles was also demonstrated as an illustrative application. These biologically inert microparticles will find many more practical applications with additional fine-tuning modifications based on discussed considerations. [ABSTRACT FROM AUTHOR]

Purifying ribonucleic acid (RNA) obtained from cells is an essential process in gene analysis and is generally performed using a polythymine oligonucleotide column and an organic solvent. However, these procedures are expensive and complicated. In the present study, we discovered that amino silica with a particle size of 50 nm was able to selectively adsorb RNA and investigated how varying the parameters of this material (i.e. mesopore existence, particle size, surface amino content, and pore diameter) affected the amount of RNA it could adsorb and its selective adsorption ability. Particle size and surface amino content were found to be important factors for RNA/deoxyribonucleic acid (DNA) value (RNA adsorption amount/DNA adsorption amount), and the presence of mesopores was found to promote the amount of nucleic acid that could be adsorbed. Mesoporous silica (MPS) with a particle size of 50 nm was synthesized using a 12/1 ratio of tetraethoxysilne/aminopropyltriethoxysilane, which acts as a silica source. The MPS was also found to have a high RNA adsorption capacity (272.6 μg/mg) and RNA selective adsorption ability (RNA/DNA value = 11.1). [ABSTRACT FROM AUTHOR]

We report that the addition of a small amount of cellulose nanofibers (CNFs) into an aqueous dispersion of colloidal particles suppresses the coffee-ring effect when the dispersion dries on a solid substrate, as revealed by the computational analysis of experimental time-series images and by particle image velocimetry. The addition of CNFs is much more effective than the increase of colloidal particle concentration at the same weight percentage; it is also more environment friendly than the use of typical molecular surfactants. This finding is promising for the fabrication of metamaterials from colloidal dispersions and for ink printing in electronics, where CNFs can also serve as a substrate for flexible devices. [ABSTRACT FROM AUTHOR]

The mineral processing industry relies heavily on froth flotation to beneficiate complex minerals. The performance of the process depends on a multitude of chemical reagents affecting the solid mineral particles as well as the air bubbles used to collect the valuable mineral particles. In flotation, bubbles and froths are transiently stable by the use of a frothing agent or the presence of inorganic electrolytes in the process water. This review presents the primary stages characterizing bubble coalescence. The effect of flotation reagents and inorganic electrolytes on the stability of bubbles and the mechanisms which delay the coalescence of bubbles are discussed. Recently it had been proposed that solid particles external to the flotation system may be intentionally added to stabilize the froth phase, which has attracted attention from the flotation community. This gave rise to additional studies on the topic. The final section of the paper was therefore designed to capture the progress made on this particular subject. The use of solid flotation aids offers a promising future to increase the recovery of valuable particles as these external particles may be customized. The advantage of solid particles over soluble reagents is that they may be recovered and re-used making them environmentally and economically attractive. [ABSTRACT FROM AUTHOR]

A composition of Al89Fe8Ti2Zr1 (at %) alloy was produced by using atomising powder metallurgy and subsequent hot-extrusion technique. Fine particle with a diameter smaller than 10 μm was formed by the atomised powders. The rod-shaped bulk sample with a diameter of 8 mm was obtained by hot-extrusion. The microstructural analysis of the alloy was characterised by X-ray diffraction, scanning and transmission electron microscopy. As per energy-dispersive X-ray spectroscopy analysis, the phase composition of the bulk alloy consists of α-Al and Al13Fe4 phases. The Vickers hardness of the bulk alloy was measured 160 HV, the tensile strength and elongation of the alloy after deformation treating was 600 MPa and 9% at room temperature. The bulk alloy shows excellent properties compared with conventionally produced Al alloy because of the dense structure by preparation technology. [ABSTRACT FROM AUTHOR]

Heat exchangers used for treated sewage energy recovery usually suffer from the composite fouling problem, which seriously impairs the heat transfer efficiency. Treated sewage heat exchanger composite fouling is mostly composed of biofouling and is notably affected by interactions between the biofouling and suspended matter. Experiments were performed using simulated treated sewage and two kinds of simulated suspended matter, silicon dioxide particles and polyamide filaments, to model the interactions. Different flow velocities, particle sizes and concentrations were tested with their influences presented by the fouling wet weight changes. Empirical equation and threshold were developed based on the results to predict whether the suspended matter promotes or impedes fouling growth. The results indicate that proper control of the flow velocities, particle sizes and concentrations of suspended matter using empirical equation and threshold can inhibit fouling by reducing unwanted positive interactions and promoting beneficial negative interactions. The filament interactions were analysed and the unique attachment mechanisms of filaments were discussed for the first time. [ABSTRACT FROM AUTHOR]

A computational model for flow and particle deposition in a three-dimensional representation of the human nasal cavity is developed. Simulations of steady state and dynamic airflow during inhalation are performed at flow rates of 9-601/min. Depositions for particles of size 0.5-20 μm are determined and compared with experimental and simulation results from the literature in terms of deposition efficiencies. The nasal model is validated by comparison with experimental and simulation results from the literature for particle deposition under steady-state flow. The distribution of deposited particles in the nasal cavity is presented in terms of an axial deposition distribution as well as a bivariate axial deposition and particle size distribution. Simulations of dynamic airflow and particle deposition during an inhalation cycle are performed for different nasal cavity outlet pressure variations and different particle injections. The total particle deposition efficiency under dynamic flow is found to depend strongly on the dynamics of airflow as well as the type of particle injection. [ABSTRACT FROM AUTHOR]

How the type of protein influences particle morphology remains a hot topic of debate. In this study we focused on the drying behavior of two major milk protein types; that is, whey protein and native micellar caseins. To improve understanding of the role of each protein in the particle-forming mechanisms, seven mixtures containing different whey proteins to caseins ratios were investigated. A monodisperse spray dryer (MDSD) was used to produce uniform particles by drying monodispersed droplets in a hot, dry air flow. Single particles were also obtained from the same material using single droplet drying in a pendant configuration. Powders were characterized according to their physical characteristics and their rehydration properties. It was demonstrated that particle morphology was mainly governed by the type of protein matrix, almost regardless of the drying kinetics, which differed considerably between MDSD and single droplet drying. Controlling product formulation thus represents a potential means by which to tune particle morphology and therefore the functional properties of powder. [ABSTRACT FROM PUBLISHER]

Diameter of a collection of different-size spherical objects such as particles, droplets, and bubbles can be represented by a single value called the mean diameter. There are many ways of calculating and expressing the mean diameter of particulate matter. One of them is the Sauter mean diameter also called the surface-volume mean diameter. This diameter has been extensively used in numerous publications without paying attention to its physical meaning. In this article, the physical meaning of the Sauter mean diameter of spherical objects was derived and presented. The Sauter mean diameter of a collection of spherical objects of different sizes is equal to the diameter of equisized spherical objects forming a collection. The polysized and equisized systems have different numbers of spherical objects, identical total surface area, and identical total volume. If the surface energy of all spheres of both systems is the same, they can be called equienergetic. [ABSTRACT FROM PUBLISHER]

The total settled mass of waxy crude oil has a close relationship with the particle size distribution of wax crystals. Wax crystal images of four kinds of crude oils were obtained with OPTIPHOT2-POL polarizing microscope. The wax particle size distribution was confirmed by image processing and data analysis. The results strongly suggest that wax particle size correspond to gamma distribution. Moreover, the range of wax particle size distribution expands with the increasing of temperature. [ABSTRACT FROM AUTHOR]

In this study, we introducedN-hydroxymethyl acrylamide and an organic montmorillonite intercalated by an octadecyl trimethyl ammonium bromide surfactant together into the in situ polymerization of polyvinyl acetate to form exfoliated nanocomposites. Wide-angle X-ray diffraction, Fourier transform infrared spectroscopy, transmission electron microscopy, power-law function equation, Newtonian fluid flow equation, Cross-Williamson model viscous equation, Hooke's law, and Poisson's ratio equation revealed the structures, dispersion, rheology, and static tensile properties. The exfoliated nanocomposites were pseudo-plastic non-Newtonian fluids, presented a good dispersion in water, a great storage stability, and a high static tensile strength at 6.78–8.06 MPa. [ABSTRACT FROM PUBLISHER]

Multiscale modelling has great advantages by simulating material behaviours on one level using information from another level. The popular multiscale methodology couples the atomistic/meso particle model with the continuum model (e.g., multiscale model by coupling molecular dynamics and finite element analysis). In this paper, a new multiscale method is proposed using the numerical manifold method (NMM) and its micro extension particle manifold method (PMM). Due to the same mathematical and mechanical scheme NMM and PMM adopt, their multiscale coupling has a uniform framework and does not need special treatment at the multiscale boundary. The proposed method has an advantage over PMM in presenting the material’s micro structure and failure description. It also saves the computational resource by using NMM to present the macro part. In the paper, the multiscale methodology is presented with some numerical demonstrations. It is proven that this novel multiscale manifold method is a good tool for analysis of geomaterials. [ABSTRACT FROM AUTHOR]

Controlling the particle size distribution (PSD) of raw materials, intermediates, and end products is very critical to the success of the powder technology related processes. This study presents the evaluation of the sieving characteristics of some industrial minerals, namely, quartz, talc, and barite, and the establishment of possible correlations between the PSD and kinetics parameters. PSD of the −600 µm fractions of quartz, talc, and barite minerals were plotted in Schuhmann mathematical approach. The size modulus (ks) and distribution modulus (αs) were obtained for each mineral. Then, sieving kinetics study was carried out for each mineral to determine optimum sieving time and sieving rate constant (kk). Further, the size distribution parameters were correlated with the sieving rate constant values for those minerals. While distribution modulus (αs) increases, size modulus (ks), and average sieving rate constant values (kk) decrease. The correlations were found to be ks = −293.52αs + 730.87 and kk = −0.0041αs + 0.0454. The results showed that near-mesh particles play important role in the overall kinetic process. [ABSTRACT FROM AUTHOR]

Granular lost circulation material (LCM) is the most commonly used material to reduce drilling fluid loss in drilling industry. Although, the plugging role of granular LCM in fracture is widely accepted by drilling engineers, the control and optimization are still limited due to the lack of the fundamental understanding of the LCM plugging process. This article presents a numerical study of the granular LCM plugging behavior at a particle scale by means of discrete element method (DEM). The effects of the particle shape, size distribution, and concentration on the fracture-plugging performance are studied by a series of controlled numerical experiments. The results are analyzed in terms of plugging depth and time spent before plugging. They are useful to the development of a better understanding and the control of granular LCM plugging process in fractures. [ABSTRACT FROM AUTHOR]

In this study, an analytical cutting force model has been presented for mill-grinding SiCp/Al composites. In this model, except the chip formation force and frictional force components, debonding and particle fracture force components are considered in modeling the total force. The energy theory of particle fracture and Griffith theory of fracture were applied in developing the debonding and particle fracture force components during mill-grinding SiCp/Al composites. Results of verification experiments for the developed cutting force model reveal that the mean forecast error of this developed cutting force model is less than 8% excluding few experimental values which deviate far from the corresponding theoretical model values, and has acceptable agreement with the experimental values under different machining conditions. [ABSTRACT FROM AUTHOR]

In the present work the agglomeration of a natural organic solid in a top-spray fluidized bed at bench scale was studied by means of statistical analysis and modeling using a discretized population balance. These engineering approaches were coupled to elucidate the influence of elutriated fines recirculation and its interaction with bed temperature and atomizing binder time on agglomeration mechanisms of solids presenting initial particle diameter polydispersity. First, a 23factorial design was considered, accounting for the factors of atomizing binder time and bed temperature with and without consideration of the recirculation of elutriated fines into the fluidized chamber. Second, the agglomerate observations were analyzed by a variance analysis, with a significance level of 5%, using the mean particle diameter as response variable. Finally, the observations were predicted through a discretized population balance accounting for nucleation, agglomeration, and growth kinetics. The results indicated that bed temperature and atomizing binder time, together with the interaction between bed temperature and the recirculation of elutriated fines, were factors affecting agglomeration mechanisms. Nucleation and aggregation mechanisms were dominant when the lowest bed temperature and the longest atomizing binder time under fines recirculation conditions were used. [ABSTRACT FROM AUTHOR]

Discontinuous particle films of polystyrene (PS) with different molecular weights were prepared by the methods of spin coating (SPC) and droplet evaporation (DE) at room temperature on mica substrates. Visualization and characterization of these samples were performed by atomic force microscopy (AFM). The results showed that the dimensions of the particles in the films increased with molecular weight. The dimensions of the particles in the films derived from SPC exhibited better uniformity than those from DE. During the steps of particle film formation by SPC, the PS molecules gathered in large clusters at the early stage, then the polymer aggregates were separated or spun off, and more and more particles emerged, finally the clusters vanished and the particle film formed. The particles of the spin-coated film dewetted after annealing and numerous individual polymer chains appeared newly on the mica substrate. [ABSTRACT FROM AUTHOR]

A total of 19 honey samples, mostly from Germany but also from France, Italy, Spain and Mexico, were analysed for non-pollen particulates. Only coloured fibres and fragments were quantified. Transparent fibres, considered to be cellulosic because they could be stained with fuchsin, were not quantified. Coloured material was found in all the samples investigated. Fibre counts ranged from 40/kg to 660/kg of honey, with a mean value of 166 ± 147/kg of honey, whereas fragments were considerably less abundant (0–38/kg of honey; mean 9 ± 9/kg of honey). Sources are tentatively identified as environmental, that is particles having been transported by the bees into the hive, or having been introduced during honey processing or both. In addition, five commercial sugars were analysed. In all the refined samples, transparent and coloured fibres (mean 217 ± 123/kg of sugar) and fragments (32 ± 7/kg of sugar) were found. Unrefined cane sugar had 560 fibres and 540 fragments per kilogram of honey. In addition, in both honey and sugar samples, granular non-pollen material was observed. [ABSTRACT FROM PUBLISHER]

In this work, three nickel-cobalt-phosphorus composite coatings co-deposited with particles of silicon carbide of three different sizes (40, 200, and 800 nm) were prepared on aluminum alloys using electroless deposition. The fabrication process of composites has been discussed, and the effect of the particle size of silicon carbide on microhardness and corrosion resistance of composites has been studied. The morphology, composition, microstructure, microhardness, and corrosion resistance of deposits were characterized by scanning electron microscopy, energy dispersive spectroscopy, X-ray diffraction, Vickers hardometer, and electrochemical workstation, respectively. The results reveal that the particle size has not much effect on the deposition rate of coatings; however, the coating codeposited with smaller particles has greater incorporation amount of particles in number density, less porosity, and finer grains. Furthermore, the incorporation of smaller particles leads to higher hardness and better corrosion resistance of coatings. [ABSTRACT FROM PUBLISHER]

Calcium phosphate materials have been used increasingly in the past 40 years as bone graft substitutes in the dental and orthopedic fields. Accordingly, numerous fabrication methods have been proposed and used. However, the controlled production of spherical calcium phosphate particles remains a challenge. Since such particles are essential for the synthesis of pastes and cements delivered into the host bone by minimally-invasive approaches, the aim of the present document is to review their synthesis and applications. For that purpose, production methods were classified according to the used reagents (solutions, slurries, pastes, powders), dispersion media (gas, liquid, solid), dispersion tools (nozzle, propeller, sieve, mold), particle diameters of the end product (from 10 nm to 10 mm), and calcium phosphate phases. Low-temperature calcium phosphates such as monetite, brushite or octacalcium phosphate, as well as high-temperature calcium phosphates, such as hydroxyapatite, β-tricalcium phosphate or tetracalcium phosphate, were considered. More than a dozen production methods and over hundred scientific publications were discussed. [ABSTRACT FROM AUTHOR]

This review summarizes the research progress made so far on electret air filters used for separation of airborne particles from complex air stream. A set of different categories of these filters are delineated and the methods of manufacturing of these filters are described. The principles and mechanisms of filtration and modeling of pressure drop by these filters are analyzed. The filtration performance of these filters is discussed along with their specific advantages and limitations. The reliability of these filters is reported in terms of their charge storage capability. Many interesting inventions as reported on electret air filters in the recent patents are discussed. The latest regulations on air filters are described and how they are driving electret filter research is indicated. Specific research needs are highlighted with a view to further improve the filtration performance and long-term effectiveness of these filters. [ABSTRACT FROM AUTHOR]

A consolidated mathematical formulation of the spherically symmetric mass transfer problem is presented, with the quasi-stationary approximating equations derived from a perturbation point of view for the leading-order effect. For the diffusion-controlled quasi-stationary process, a mathematically complete set of the exact analytical solutions is obtained in implicit forms to cover the entire parameter range. Furthermore, accurate explicit formulas for the particle radius as a function of time are also constructed semi-empirically for convenience in engineering practice. Both dissolution of a particle in a solvent and growth of it by precipitation in a supersaturated environment are considered in the present work. [ABSTRACT FROM PUBLISHER]

In our previous 2D axisymmetric study of the spray-drying process, it was shown that the introduction of comprehensive formulation of drying kinetics had a substantial influence on both predicted gas and particle flow patterns in a spray dryer. On the other hand, it was demonstrated that the concept of 2D axisymmetric modeling is suitable for fast and low-resource consumptive numerical calculations of the spray-drying process and that the predicted velocity, temperature, and vapor mass fraction are of reasonable accuracy. However, due to their restrictions, 2D axisymmetric simulations fail to predict asymmetry of flow patterns and the presence of the transversal air flow and cannot provide actual 3D representation of particle trajectories inside the spray chamber. Therefore, in the present study a novel 3D theoretical model of multiscale multiphase transport phenomena in a steady-state spray-drying process is proposed for predicting more realistic particles paths, residence times, temperatures, and moisture contents. A drying process of silica slurry in a short-form pilot-scale spray dryer fitted with a pressure nozzle atomizer is investigated. The simulated 3D drying behavior of the dispersed phase and flow patterns of air velocity, temperature, and humidity are compared with the previously published results of 2D axisymmetric modeling. A significant influence of both drying kinetics and number of utilized dimensions on the predicted particle trajectories and transport phenomena in the drying chamber is observed. Hence, a proper formulation of the droplet drying kinetics and realistic 3D flow modeling is crucial for accurate numerical representation of the actual spray dryer performance. [ABSTRACT FROM AUTHOR]

The main goal of this work is the development of a fixed-grid method to model unsteady partial oxidation of a solid with implicit tracking of the interface. As a first step diffusive oxidation of a spherical coal particle is considered. The energy and species conservation equations formulated in spherical coordinates are discretised using the finite-volume approach. The boundary conditions for the temperature and species mass fractions at the solid–gas interface are modelled via special source terms activated in the interface cells. The numerical model was validated against analytic one- and two-film models for coal combustion in a dry-air atmosphere. Very good agreement was obtained. Based on the model developed a numerical study was carried out on the influence of water vapour on the partial oxidation of a spherical coal particle. Numerous numerical simulations were performed for particle diameters in the range 200×10−6 m to 2×10−2 m. The ambient temperature was varied in the range between 700 and 3000 K. The analysis of results showed that the addition of H2O has an influence on the solution convergence due to the catalytic effect of water in the coal monoxide oxidation reaction making the whole system stiffer. However, at the same time, it was found that if the ambient mass fraction of water vapour is below 1×10−3, its influence on combustion rates is minimal. The results of numerical simulations obtained for higher H2O concentration (>1×10−3) are discussed. [ABSTRACT FROM AUTHOR]