Fine Size Range Research Articles

Grain Size Tailoring to Control Strain Hardening and Improve the Mechanical Properties of a CoCrFeNiMn High-Entropy Alloy

An equiatomic CoCrFeNiMn high-entropy alloy was processed by severe plastic deformation followed by post-deformation annealing over a range of temperatures and times leading to a wide range of grain sizes from ~ 0.05 to ~ 70 μm. The results demonstrate there is a sharp evolution in grain size and hardness after annealing above 800 °C due to coarsening facilitated by the dissolution of precipitates together with a high rate of diffusion at high temperatures. Grain growth behavior revealed an incremental low value grain growth exponent with increasing annealing temperature together with a high value activation energy for grain growth of ~ 440 kJ mol−1. A critical grain size of ~ 2 µm is proposed in which deformation-induced twinning is suppressed during plastic deformation. Nevertheless, slip and deformation-induced twinning are deformation mechanisms occurring in samples with grain sizes above this critical value. A model is presented for engineering the grain size by controlling the annealing parameters in the fine grain size range to benefit from the advantages of deformation-induced twining in the CoCrFeNiMn alloy.

McIntyre Powder and its potential contributions to cardiovascular disease risk: A literature review through the McIntyre Powder historical lens.

McIntyre Powder (MP) is a fine aluminum powder that was developed to prevent silicosis in gold and uranium mine workers in Ontario, Canada, and was administered to miners there from 1943 to 1979. Mine workers were exposed to high concentrations (35.6 mg/m3) of MP for approximately 10 min before every work shift. Contemporary physical and chemical characterizations of this powder have revealed that 12% of the powder is in the ultrafine particle size‐range (nanoparticles); and the remaining 88%, in the fine particulate size range (below 2.5 µm in diameter). The confluence of ultrafine particulate (UFP) composition and high airborne concentration of MP would be expected to overwhelm the defense mechanisms of the lung and increase the lung dust burden of the mine worker exposed to respirable dust in the mine. Published studies revealing associations between air pollution particulates and increased risk for cardiovascular disease (CVD) shown a dose–response relationship with ambient PM2.5 and UFP and suggest that miners exposed to MP may also be at increased risk of CVD. The historical perspective of the use of MP in northern Ontario hard‐rock mines and its potential implications for CVD in exposed mine workers are discussed.

Evaluation of grit properties at a medium-capacity wastewater treatment plant: A case study

The optimized, tailored approaches in the design of wastewater treatment plants (WWTPs) minimize expenditure of the resources, increase treatment effectiveness, and prolong useful life of the infrastructure. In this study, wastewater grit characteristics were evaluated over the course of one year at the headworks and collection network of the Atlantic County Utilities Authority (ACUA) WWTP, located in New Jersey, USA. The mixed grit at the ACUA WWTP can be characterized as particles prevalently in the fine sand size range with high content of organic matter, low fraction of fats, oils, and grease (FOG), and very low settling velocity. A significant seasonal variability was observed in the measured parameters. These results will be utilized in the design of the most effective, fiscally responsible, and sustainable method of grit removal at the study site and may serve to promote utilization of WWTP-specific design at other facilities.

Effect of Fine Aggregate Particle Size on Physical, Mechanical, and Durability Properties of Ultra-High Performance Concrete

Ultra-high performance concrete (UHPC) mixtures are typically developed using fine aggregate with a maximum size of 600 μm. From a sustainability point of view, use of larger size fine aggregate particles in UHPC mixtures should be investigated to reduce labor costs associated with sieving, to reduce wastage of sand, and to improve sustainability. This experimental research investigates the physical, mechanical, and durability properties of UHPC incorporating coarser fine aggregates with maximum particle size of 4.75 mm replacing fine sand. Both plain and fiber reinforced UHPC mixtures were developed with a target static flow of 200 mm (8 in.) and target compressive strength of 120 MPa (17,000 pounds per square inch). Three different curing regimens were investigated: moist curing, warm bath curing at 90°C, and heat curing at 90°C. Compressive and split tensile strengths, permeable porosity, and rapid chloride permeability tests were performed to study the effect of coarser fine aggregate sizes on these UHPC properties. Increasing the maximum fine aggregate particle size range did not affect the workability, compressive strength, permeable porosity, or chloride ion ingress; however, a limited decrease in split tensile strength was observed. A change in aggregate size may have a very large impact on fiber dispersion, embedment, and crack bridging. The experimental results highlight the potential of coarser fine aggregate used in UHPC.

Higher viral load and infectivity increase risk of aerosol transmission for Delta and Omicron variants of SARS-CoV-2

Airborne transmission of SARS-CoV-2 is an important route of infection. For the wildtype (WT) only a small proportion of those infected emitted large quantities of the virus. The currently prevalent variants of concern, Delta (B1.617.2) and Omicron (B.1.1.529), are characterized by higher viral loads and a lower minimal infective dose compared to the WT. We aimed to describe the resulting distribution of airborne viral emissions and to reassess the risk estimates for public settings given the higher viral load and infectivity. We reran the Monte Carlo modelling to estimate viral emissions in the fine aerosol size range using available viral load data. We also updated our tool to simulate indoor airborne transmission of SARS-CoV-2 by including a CO2 calculator and recirculating air cleaning devices. We also assessed the consequences of the lower critical dose on the infection risk in public settings with different protection strategies. Our modelling suggests that a much larger proportion of individuals infected with the new variants are high, very high or super-emitters of airborne viruses: for the WT, one in 1,000 infected was a super-emitter; for Delta one in 30; and for Omicron one in 20 or one in 10, depending on the viral load estimate used. Testing of the effectiveness of protective strategies in view of the lower critical dose suggests that surgical masks are no longer sufficient in most public settings, while correctly fitted FFP2 respirators still provide sufficient protection, except in high aerosol producing situations such as singing or shouting. From an aerosol transmission perspective, the shift towards a larger proportion of very high emitting individuals, together with the strongly reduced critical dose, seem to be two important drivers of the aerosol risk, and are likely contributing to the observed rapid spread of the Delta and Omicron variants of concern. Reducing contacts, always wearing well-fitted FFP2 respirators when indoors, using ventilation and other methods to reduce airborne virus concentrations, and avoiding situations with loud voices seem critical to limiting these latest waves of the COVID-19 pandemic.

Electrical installations running through masonry walls: developing waste generation indicators for environmental performance analysis

Waste generation is one of the most relevant environmental aspects of the construction industry. About 47 million tons of construction and demolition waste are collected annually by Brazilian municipalities. One of the activities that generates waste is cutting chases on walls for installations. However, there are no waste generation indicators for this activity. Understanding waste generation processes enables managers to prevent them and promote their proper environmental management. This study assessed the generation of waste resulting from the cutting of clay bricks for electrical installations using three tools: milling cutter, marble saw, and cold chisel. The study included data collected from residential construction works and experimental data collected from the construction of real-scale walls. In a laboratory, five different wall configurations were built and the three tools mentioned were used to cut a chase on the walls. The results were statistically analyzed to define a waste generation index (WGI) by linear regression. The type of tool employed had no influence on the waste generation index, which was 26.5 ± 2.6 kg/m2. However, the tools used directly influenced the quality of the service, productivity, and the volume of waste generated. The waste from the milling cutter showed the smallest maximum aggregate size and the largest bulk density, followed by the waste resulting from the marble saw and the cold chisel. The marble saw and cold chisel waste samples had around 78% of their composition in the coarse aggregate grain size range. The milling cutter waste samples were the finest and had on average 60% of their composition in the fine aggregate grain size range. The width of the chases made with the milling cutter were smaller and more consistent than those made with the cold chisel, which showed irregularities and larger dimensions than necessary. From the waste generation indicators obtained in this study, construction managers will be able to choose more appropriate cutting tools and improve their planning and management systems to minimize associated environmental impacts.

Size-fractionated PM-bound PAHs in urban and rural atmospheres of northern Thailand for respiratory health risk assessment

Size-fractionated particulate matters (SPMs) in a range of 9.0 to 0.43 μm, classified based on aerodynamic diameter (dae) as fine PMs (0.43 μm ≤ dae < 2.1 μm) and coarse PMs (2.1 μm ≤ dae < 9.0 μm) were collected by cascade impactors (7 fractions) during smoke haze (SH) and non-smoke haze (NSH) seasons in urban and rural areas of Chiang Mai, Thailand. Their polycyclic aromatic hydrocarbons (PAHs) compositions were determined for respiratory health risk assessment. During SH episode, concentrations of SPMs and PAHs in the rural area were approximately two times higher than in the urban area and about 62–68% of the SPMs were fine particles. Conversely, during NSH season the concentrations in the urban area were higher due to traffic emission. The finest particle sizes (0.65–0.43 μm) contained the highest PAHs concentrations among the other PM sizes. Benzo[b]fluoranthene was a main PAH component found during SH season suggesting biomass burning is a major pollutant source. High molecular weight (5–6 rings) PAHs with high carcinogenicity were likely to concentrate in fine particles. Distribution patterns of SPMs and PAHs during SH season were bimodal with the highest peak at a fine size range (0.65–0.43 μm) and a small peak at a coarse size range (5.8–4.7 μm). Respiratory health risk was estimated based on toxicity equivalent concentrations of PAHs bound-SPMs and inhalation cancer risk (ICR). Relatively high ICR values (1.14 × 10−4 (rural) and 6.80 × 10−5 (urban)) were found during SH season in both areas, in which fine particles played an important role. It revealed that high concentration of fine particles in ambient air is related to high respiratory health risk due to high content of carcinogenic substances.

Direct visualisation of bubble-particle interactions in presence of cavitation bubbles in an ultrasonic flotation cell

In this study, the role of cavitation bubbles in the bubble-particle interaction dynamics was investigated using high-speed imaging. A lab-scale conceptual flotation cell was designed involving an ultrasonic field with adjustable power output and a continuous liquid recirculation stream. Coarse size range hydrophobic glass Ballotini particles were suspended in the cell by the combined action of a confined vortex and turbulence created by periodic ultrasonic pulses. Ultrasonic pulses in the liquid medium led to the generation of numerous fine size range cavitation bubbles which were observed to form particle clusters. These particle clusters were observed attaching to relatively larger size carrier bubbles forming stable bubble-particles aggregates, which subsequently floated. It was noted that a favourable state of bubble-particle interactions was achievable to produce such stable bubble-particles aggregates by suitably controlling the input power and period of the applied ultrasonic pulse.

Thermally Assisted Grinding of Cassiterite Associated with Pollimetallic Ore: A Comparison between Microwave and Conventional Furnaces

We investigated the influence of microwave and conventional heating pretreatments on the grinding of cassiterite associated with pollimetallic ore. The minerals that exhibited a stronger microwave absorption ability crushed first, which is the main difference between the microwave and the traditional heating pretreatments. The distribution of Fe, Pb, Zn, and Sn increased in the fine size range (−0.425 mm). The Fe and Pb grades in the size ranges of −3.2 + 2 mm and −2 + 1 mm after the microwave pretreatment (6 kW, 1 min) were lower than those of the traditional heating (12 kW, 400 °C, 20 min), indicating that the microwave selective heating was beneficial for pyrite and jamesonite. The grade and distribution of Sn decreased significantly in the size ranges of −3.2 + 2 mm and −2 + 1 mm and increased in the size ranges of −0.425 + 0.15 mm and −0.15 + 0.074 mm. Microwave heating treatment promoted the grinding of sulfide ore and reduced the cassiterite overgrinding.

The removal of lead from chalcopyrite surfaces in relation to radionuclide removal from copper minerals

Surface contaminants, specifically arsenic, mercury, bismuth and radionuclides, present environmental and health concerns and prove challenging to separate in processing plants due to the nature of their association with mineral surfaces. This paper explores alternative methods to the existing hydrometallurgical and pyrometallurgical techniques for separating said radionuclide from economically important copper resources. This study uses Cryogenic X-ray Photoelectron Spectroscopy to determine what species form on the surface of chalcopyrite (a major copper mineral) when it is exposed to lead nitrate, a proxy for radionuclide 210Pb. It then uses Time-of-Flight Secondary Ion Mass Spectrometry to investigate the impact of both tumbling and stirred regrinding on the prevalence and distribution by size of lead phases on the chalcopyrite surface. PbS, PbSO3, PbSO4 and PbO were all detected on the chalcopyrite surface throughout the various processing stages. Stirred regrinding removed 38.5% of the lead from the chalcopyrite surface compared to 5.4% of lead removed by tumbling regrinding. Additionally, stirred regrinding caused lead to be concentrated in the fine particle size range (<25 μm), a phenomenon not observed in the tumbling regrinding scenario. This was attributed to the abrasion breakage mechanism that is dominant in stirred regrinding causing the lead phases to be liberated from the chalcopyrite surface as fine particles. A novel application of stirred regrinding to the removal of strongly-adsorbed radioactive contaminants from copper is proposed to facilitate lead removal with minimal “clean” chalcopyrite loss. This process could potentially be applied to remove other surface contaminants as well.

Molecular Speciation of Size Fractionated Particulate Water-Soluble Organic Carbon by Two-Dimensional Nuclear Magnetic Resonance (NMR) Spectroscopy.

Particulate matter is associated with increased morbidity and mortality; its effects depend on particle size and chemical content. It is important to understand the composition and resultant toxicological profile of particulate organic compounds, the largest and most complex fraction of particulate matter. The objective of the study was to delineate the nuclear magnetic resonance (NMR) spectral fingerprint of the biologically relevant water-soluble organic carbon (WSOC) fraction of size fractionated urban aerosol. A combination of one and two-dimensional NMR spectroscopy methods was used. The size distribution of particle mass, water-soluble extract, non-exchangeable organic hydrogen functional types and specific biomarkers such as levoglucosan, methane sulfonate, ammonium and saccharides indicated the contribution of fresh and aged wood burning emissions, anthropogenic and biogenic secondary aerosol for fine particles as well as primary traffic exhausts and pollen for large particles. Humic-like macromolecules in the fine particle size range included branched carbon structures containing aromatic, olefinic, keto and nitrile groups and terminal carboxylic and hydroxyl groups such as terpenoid-like polycarboxylic acids and polyols. Our study show that 2D-NMR spectroscopy can be applied to study the chemical composition of size fractionated aerosols.

Regional and Transported A erosols in Ambient A tmosphere of Raipur,India, during W inter

Size fractionated atmospheric aerosols were collected using cascade impactor sampler on quartz flter substrate during October 2015 to February 2016 in campus of Pt Ravishankar Shukla University of Raipur Chhattisgarh. The size of aerosol particles is of crucial importance to several processes in the atmosphere. The relative concentrations in both modes are responsible for the variability observed in the shape of the size distribution. Characteristic size distributions of measured aerosol over central India showed identifcation of three main behaviour types during entire study period: (i) month in which bimodal size distribution dominated in coarse mode (October 2015, 5 December 2015 and January, 2016), (ii) those months in which bimodal distribution equally intense in both one, and coarse modes (November, 2015) and (iii) those which were mainly dominated within fine (February, 2016, December, 2015). The two-subsequent month namely November 2015 and December 2015 shows bimodal size distribution with dominance in fine size range in comparison to coarse mode, possibly these high loading of one particles is due to long range transport. The peculiar observation of air trajectory shows that there is increase in fine particles concentration during December 2015, although there in increase in temperature and wind speed. The reason for this high concentration is long range transport of air masses. However, January has normal trend in particular matter concentration. The important finding of the present study based on characteristic size distribution and air trajectory plots accomplishes that fine particles are obtained through long range transport whereas coarse particles are mainly from local origin.

Herbal nanoemulsion in topical drug delivery and skin disorders: Green approach

A topical drug delivery system can be a future trend for drug delivery because of the availability of the largest surface area of skin than any other organ. Although the skin has some advantages such as ease of application, patient compliance, and safety, it has many disadvantages such as permeability and bioavailability via first-pass metabolism and others. Nanoemulsion can be a future trend for topical delivery of drugs because of its very fine droplet size range, lipophilic and/or hydrophilic nature, and suitability for various administration routes such as parenteral, oral, topical, intranasal, ocular, and pulmonary. The contents of nanoemulsions make them suitable for human use because the oil/lipid, water, surfactants, and co-surfactants used in the formulation of nanoemulsion are relatively safe and nontoxic. Nowadays, people are more attracted to natural preparations as of their inherited qualities and fewer side effects. Due to herbal drugs’ compatibility in nanoemulsion, it is considered the best technology for the green approach of the medicine system. The article presented the foundation for the above statement by different literature surveys on the herbal nanoemulsion formulations.

Heat-induced hollow microcapsule formation using fava bean legumin

This study evaluated the effects of extrinsic factors on the formation of hollow microcapsules (HMs) using fava bean legumin. It was found that the ability of HM formation was highly dependent on NaCl concentration, heating temperature and pH value, where the optimum conditions were 0.05 M NaCl, temperature close to 80 °C and pH 7.17. The protein concentration in the range of 2–10 g/L had minimal influence on the ability of HM formation, while higher protein concentration contributed to form more HMs. The size of the majority of particles allocated within a fine micrometer size range of 1–10 μm and the hollow internal structure exhibited either one vacuole or multi-vacuoles. Formation of NaCl-induced relatively stable, small protein micro-domains could be regard as a precursor of the subsequent HM formation via heating, and the hollow structure could be induced by a balance of partial dispersion of proteins from the clusters to the aqueous phase and formation of permanent linking between the remaining proteins.

Atomic-scale investigation on the structural evolution and deformation behaviors of Cu–Cr nanocrystalline alloys processed by high-pressure torsion

Abstract A systematic investigation based on high-resolution transmission electron microscopy (HRTEM) and quantitative analysis was carried out to gain insights into the structural evolution and deformation behaviors of 57 wt%Cu - 43 wt%Cr dual-phase alloys deformed by high pressure torsion (HPT). Nanometer-sized grains were obtained, with Cu and Cr grain size being reduced from 33.7 nm to 17.4 nm and 35.6 nm to 18.6 nm respectively after deformation with 5 rotations and 25 rotations. During the early deformation stage, in a way, grain refinement in Cu was controlled by the interaction between Cr solutes (or clusters) that was forced to dissolve into Cu matrix and extended dislocations motion. At the higher strain condition, the deformation mode became more complicated and the grain refinement of Cu and Cr can be affected by solute effects and constraint effect during severe plastic deformation in this dual-phase system. In addition, inverse grain-size effect on stacking fault (SF) and twinning tendencies was observed in Cu under different deformation conditions. A critical grain size was calculated to describe the required shear stress for partial dislocation nucleation. HRTEM investigations and statistical analysis on twins observed in 25 rotations-strained sample reveal that the twins are associated with the grain boundary activities and the recovery procedure in the extremely fine grain size region. These atomic-scale observations provide new views in understanding the deformation mode, especially twinning behavior in the extremely fine grain size range below the critical grain size that are hardly obtained in experiments.

Influence of Regional Transport Mechanisms on the Fingerprint of Biomass-Burning Aerosols in Buenos Aires

The study focuses on the transport of aerosol particles resulting from biomass burning in central South America towards the megacity of Buenos Aires by the South American Low-Level Jet. In particular, the cases are studied in which the exit area of the Jet reaches the La Plata Basin with no precipitation associated, herein called Chaco Jet 1 (CJ1), which could remove aerosols from the atmosphere on their way towards the city. CJ1 events registered within the five-year period of 2001–2005 are examined along with changes in the optical properties of aerosols over the city from measurements from the Aerosol Robotic Network (AERONET) site. Three-dimensional backward trajectories of CJ1 were obtained to verify the connection between the receptor site and the biomass-burning source region. A cluster analysis of the trajectories allows further characterizing the features and impacts of regionally transported aerosols. A subsample of days on which impacts of the contribution of biomass burning could have occurred, showed a statistically significant increase in aerosol optical depth and Ångström exponent, reflected by an increase in the peak of the derived volume size distribution in the fine fraction size range, which also shifts slightly towards bigger radii. The days with AOD greater than 0.15 show overall behaviour like other urban sites with pollution of different origins. The evaluation of the selected data reveals that higher values of AOD and changes in the Ångström exponent are linked to the dispersion of biomass-burning aerosols. Air mass trajectories coinciding with the CJ1 core present the strongest impact on aerosol characteristics, which can be seen in spectral measurements.

Size-segregated particulate matter bound polycyclic aromatic hydrocarbons (PAHs) over China: Size distribution, characteristics and health risk assessment

Polycyclic aromatic hydrocarbons (PAHs) associated with size-segregated particulate matter at 10 sampling sites over China which can be grouped into North China and South China, including urban site, sub-urban site, farmland site and background site, from January 2013 to December 2014 were analyzed by Gas Chromatography – Mass Spectrometry. This is the first time for comprehensive studies on the size-segregated PAHs at the national level. The spatial variations of particulate PAHs showed that Xinaghe (XH), Yucheng (YC) and Shenyang (SHY) in North China had higher particulate PAHs mass concentrations than other sampling sites. The seasonal variations of PAHs exhibited the highest mass concentrations in winter, which could be caused by the increase in emission, lower temperatures and weaker solar radiation. Particulate PAHs were found to be dominant in fine size range of <1.1 μm, the same as individual PAH compounds. The dominant species in particulate PAHs are benzo[b + k]fluoranthene (BBKF), indeno[1,2,3-cd]pyrene (IP) and benzo[g,h,i]perylene (BghiP), indicating that fossil fuel combustion could be an important source for PAHs over China. BaP, a carcinogen to humans, also had much higher mass concentrations at XH, SHY and YC in North China than other sites. Toxicity equivalent quantities (TEQ) and the lifetime excess cancer risk (ECR) analysis showed that XH, SHY and YC in North China suffered more serious health risk from PAHs than other sites. In addition, higher TEQ and higher ECR were found in the size range of <1.1 μm, indicating that finer particles are associated with higher toxicity.

Spatial and seasonal variations of sugars (alcohol) in China: Emerging results from the CARE-China network

The “Campaign on Atmospheric Aerosol Research” network of China (CARE-China) is a long-term project for the study of the spatio-temporal distributions of physical aerosol characteristics as well as the chemical components and optical properties of aerosols over China. This study presents the size-segregated sugars from the CARE-China network. Sugars associated with size-segregated particulate matter at 8 regions (North China (NC), East China (EC), Northeast China (NE), and Central China (CC), South China (SC), Northwest China (NE), Southwest China (SW) and the Tibetan Plateau (TP)) including 14 sites over China from January 2013 to December 2014 were analyzed via gas chromatography mass spectrometry. Mass concentrations of measured sugars varied considerably with location and season, ranging from 0.20 to 5588 ng m−3, with the majority from levoglucosan (170 ± 207 ngm−3, accounting for 48% of total sugars), followed by sucrose (44.6 ± 39.6 ngm−3, accounting for 11.3% of sugar), and sorbitol (35.5 ± 42.2 ng m−3, accounting for 10.0% of sugars). The highest levels of sugars were observed in urban sites in Central and Southwest China, whereas the lowest concentrations occurred in background and Tibetan Plateau sites. A distinct seasonal variability of sugars was observed, with higher in the winter or autumn and lower during the summer at urban sites. Inconsistent seasonal trends were observed at the background sites located in the higher latitudes, which were characteristic with the highest concentration occurred in spring. Levoglucosan, galactosan and mannosan were found to be dominant in fine size range <1.1 μm, accounting approximately 59% of all size-segregated sugars. Sucrose was enriched in the size range of 3.3–9.0 μm for almost all sampling sites. Concentrations of trehalose and sorbitol in the three size particles were similar. The OC from biomass burning was estimated to be in the range of 0.93–58.7 μg C m−3, with the highest level OCBB% were observed in urban sites in summer and winter. The contributions of biomass burning to OC in the rest of sites were higher in autumn and winter than in spring and summer. Higher OCBB% was observed in spring at the background sites located in Northwest and Northeast China.

Diesel exhaust particles elevate MUC5AC and MUC5B expression via the TLR4-mediated activation of ERK1/2, p38 MAPK, and NF-κB signaling pathways in human airway epithelial cells

Exposure to diesel exhaust particles (DEPs) is known to cause serious health problems, owing to a steady increase in the number of diesel vehicles worldwide. DEPs comprise approximately 90% particle mass existing in the fine size range (≤2.5 μm) and are mainly absorbed in the respiratory tract. However, limited information is available on the effects of DEP exposure on the respiratory tract in humans. Here, we investigated the effect and signaling pathways of DEPs on the expression of mucin, especially MUC5AC and MUC5B, in human airway epithelial cells by reverse-transcriptase polymerase chain reaction (PCR), real-time PCR, enzyme-linked immunosorbent assay, western blotting, and immunofluorescence staining. The signaling pathways activated following DEP-induced expression of MUC5AC and MUC5B in airway epithelial cells were analyzed by evaluating Toll-like receptor 4 (TLR4), mitogen-activated protein kinase (MAPK; extracellular signal-regulated kinase 1/2 [ERK1/2] and p38), and nuclear factor kappa B (NF-κB) phosphorylation with western blot and small-interfering RNA (siRNA) analyses. DEPs significantly increased MUC5AC and MUC5B expression in human airway epithelial cells that was closely related to TLR4, MAPK (ERK 1/2 and p38), and NF-κB pathway activation. This is the first report to demonstrate the DEP-mediated increase in MUC5AC and MUC5B expression via the TLR4-mediated activation of ERK1/2, p38 MAPK, and NF-κB signaling pathways in human airway epithelial cells.

Effects of grain size gradation on the porosity of packed heap leach beds

Fluid flow through packed ore/rock beds is among the critical processes that control the release of valuable metals as well as substances potentially harmful to the environment. The properties of fluid flow in porous media are associated with the structure of the pores through which the fluid flows which, in turn, is influenced by grain size gradation, grain shape and packing method. In this study, we investigated the effect of three types of grain size gradation on porosity and pore size distribution using the bulk density and the computed tomography (CT) scanning methods. It was generally observed with the uniformly graded grains that the porosity decreased as the mean grain size increased until a limit was reached. The porosities of the well graded grains were lower than those of the uniformly graded grains in the coarse size range, but there was no difference in the porosities between the two types of gradation in the fine size range. Furthermore, the influence of the packing method on the well graded grains was more pronounced than on the uniformly graded grains, implying relative ease of compaction of well graded grains. The proportion of fine grains in the gap graded grains influenced the porosities, which firstly decreased and then increased. The pore size distribution of the gap graded grains showed a high degree of heterogeneity compared to those of the uniformly graded and the well graded grains. The findings indicate that in ore/rock dumps fine particles account for the bulk of the porosity and possibly the bulk of any pore water content, suggesting that fine particles are likely to contribute most of the leachable substances.