Particle Size Distribution Of Material Research Articles

Quantifying Aerosolization of Facial Plastic Surgery Procedures in the COVID-19 Era: Safety and Particle Generation in Craniomaxillofacial Trauma and Rhinoplasty.

Background: COVID-19 poses a potentially significant infectious risk during procedures of the head and neck due to high viral loads in the nasal cavity and nasopharynx. Facial plastic surgery has significant exposure to these areas during craniomaxillofacial trauma procedures and rhinoplasty. Methods: Airborne particulate generation in the 1-10 μm range was quantified with an optical particle sizer in real time during cadaveric-simulated rhinoplasty and facial trauma conditions. Procedures tested included mandibular plate screw drilling, calvarial drilling, nasal bone osteotomy, nasal dorsal rasping, and piezoelectric saw use. Particulate generation was measured both adjacent to the surgical site and at surgeon mouth level (SML). Results: Mandibular plate screw drilling without irrigation generated significant particulate both adjacent to the surgical site and at SML (p < 0.01). Irrigation mitigated particulate generation at SML to nonsignificant levels. Calvarial drilling additionally produced substantial particulate above baseline adjacent to the surgical site (p < 0.01). Standard nasal osteotomies and dorsal rasping did not generate detectable airborne particulate, whereas piezoelectric saw use was associated with significant particulate generation both adjacent to the surgical site (p < 0.001) and at SML (p < 0.01). At SML, smaller particulate represented a significantly higher proportion of total particulate detected. Conclusions: The majority of craniomaxillofacial trauma procedures involve particle generation that may be limited in spread by the use of local irrigation. Most bony work involved in rhinoplasty can be safely performed without a high degree of particle formation. The use of piezoelectric instruments in rhinoplasty should be avoided when concerned for particulate generation.

A comparative study on the size distribution and carbon components of particulate matters from typical sources

AbstractA comparative study on the size distribution and carbon component of particulate matter (PM) from four typical sources in Zhenjiang, China were carried out. Two raw PM cases were collected directly from the diesel/gasoline engine, individually, while another two diluted PM cases were gleaned from the atmosphere on particular venues concerning the contribution of diesel/gasoline PMs, respectively. It was revealed that the raw diesel/gasoline PMs presented mass concentration peaks at the size range of 0.18–0.32 μm, while most of the diluted PM from the atmosphere near the chimney vent of the engine laboratory and in the basement garage concentrated at the size range of 0.32–0.56 and 1.0–1.8 μm, respectively. Via the carbon component analysis, for the raw diesel PM, the major parts of OC fractions were determined as OC1, OC2 and OC3, meanwhile EC2 took the majority of EC. As for the diluted PM from the atmosphere, OC2, OC3 and OC4, and EC1 and EC2 accounted for the main parts of OC and EC, respectively. The rate of OC to EC (OC/EC) of the PMs from the diesel engine, near the laboratory chimney vent and in the basement garage varied in a range of 0.92–2.50, 1.40–2.53, and 2.36–4.82, respectively. It is worth noting that the OC/EC of the PM collected in the basement garage exceeded 2.0, which implies that a great deal of secondary particulates were generated. Overall, this article may assist to understand the possible evolution path of PM from the raw source to the diluted status.

Seasonal variability of PM concentration in Tashkent

Several hundred cities of the world, have announced goals to become “smart” cities that include environmental sustainability, health, climate-resiliency and livability. Tashkent is capital city of Uzbekistan can count a candidate to the list of “smart” environmentally-sustainable, healthy and livable cities. To investigate the ambient mass concentration, size-distribution and seasonal variability of atmospheric particulate matter (PM), a long-term monitoring campaign was undertaken at an urban background site of Tashkent city during 3 year period (December 1, 2011-November 30, 2014). Goal of the current paper is to analyze the seasonal variations of PM10 and PM2.5 concentration in the ambient air of the city. Monitoring of PM was carried out according to requirements of European standards and during monitoring, a low-volume PNS 16T-3.1 sampler, as well as quartz and fiberglass filters with a diameter of 47 mm, were used. Diurnal concentration of particles in atmospheric air was determined by the gravimetric method. The PM concentration levels varied greatly, with higher mean mass concentrations during the heating season. For whole monitoring period average concentration of PM2.5=29.3±13.5 μg/m3 and PM10=55.4±21.7 μg/m3 and that is under interim target values but higher than WHO recommended value (respectively equal to 10 µg/m3 and 20 µg/m3). Wintertime observed high concentration of PM compared to summer and spring (average PM2.5=42.0 μg/m3 and PM10=63.7 μg/m3). Springtime observed lower concentration of PM (average PM2.5=22.3 μg/m3 and PM10=45.9 μg/m3). Highest concentration of PM was observed in February (average PM2.5=45.0 μg/m3 and PM10=67.8 μg/m3) and lowest in June (average PM2.5=19.6 μg/m3 and PM10=41.7 μg/m3).

Indoor Particulate Matter during HOMEChem: Concentrations, Size Distributions, and Exposures.

It is important to improve our understanding of exposure to particulate matter (PM) in residences because of associated health risks. The HOMEChem campaign was conducted to investigate indoor chemistry in a manufactured test house during prescribed everyday activities, such as cooking, cleaning, and opening doors and windows. This paper focuses on measured size distributions of PM (0.001-20 μm), along with estimated exposures and respiratory-tract deposition. Number concentrations were highest for sub-10 nm particles during cooking using a propane-fueled stovetop. During some cooking activities, calculated PM2.5 mass concentrations (assuming a density of 1 g cm-3) exceeded 250 μg m-3, and exposure during the postcooking decay phase exceeded that of the cooking period itself. The modeled PM respiratory deposition for an adult residing in the test house kitchen for 12 h varied from 7 μg on a day with no indoor activities to 68 μg during a simulated day (including breakfast, lunch, and dinner preparation interspersed by cleaning activities) and rose to 149 μg during a simulated Thanksgiving day.

Physico-chemical characterization of urban aerosols from specific combustion sources in West Africa at Abidjan in Côte d'Ivoire and Cotonou in Benin in the frame of the DACCIWA program

Abstract. Urban air pollution in West Africa has yet to be well characterized. In the frame of DACCIWA (Dynamics-Aerosol-Chemistry-Cloud Interactions in West Africa) program, intensive measurement campaigns were performed in Abidjan (Côte d'Ivoire) and Cotonou (Benin), in dry (January 2016 and 2017) and wet (July 2015 and 2016) seasons, at different sites chosen to be representative of African urban combustion sources, i.e., domestic fires (ADF), traffic (AT) and waste burning (AWB) sources in Abidjan and traffic source in Cotonou (CT). Both the size distribution of particulate matter (PM) and their chemical composition including elemental carbon (EC), organic carbon (OC), water-soluble organic carbon (WSOC), water-soluble inorganic ions (WSI) and trace metals were examined. Results show very high PM concentrations at all sites and a well-marked seasonality as well as a strong spatial variation. The average PM2.5 mass concentrations during the wet season are 517.3, 104.1, 90.3, and 69.1 µg m−3 at the ADF, CT, AT, and AWB sites, respectively. In the dry season, PM2.5 concentrations decrease to 375.7 µg m−3 at the ADF site, while they increase to 269.7, 141.3, and 175.3 µg m−3 at the CT, AT, and AWB sites, respectively. The annual PM2.5 levels at almost all sites are significantly higher than the WHO guideline level of 10 µg m−3. As for PM mass, (EC) and (OC) concentrations are also maximal at the ADF site, accounting for up to 69 % of the total PM mass. Such a high content is mainly linked to wood burning for domestic cooking and commercial food smoking activities. Dust contributions are dominant at CT (57 %–80 %), AT (20 %–70 %), and AWB (30 %–69 %) sites and especially in the coarse and fine-particle modes at the CT site and in the coarse fraction at the AT site, which may be explained by the impact of long-range desert-dust transport and resuspended particles from the roads, in addition to anthropogenic sources. The contributions of WSI to the total PM mass, mainly driven by chloride, nitrate, and calcium in the fine and/or large particles, are highly variable according to the sites but remain less than 30 %. Values are generally 1–3 times higher in the wet season than in the dry season. This is due not only to anthropogenic emissions but also to nitrate formation by reaction processes and natural emissions. The concentrations of trace elements reflect well the trends in dust at the traffic and AWB sites, with a predominance of Al, Na, Ca, Fe, and K, keys markers of crustal dust. This study constitutes an original database that characterizes specific African combustion sources.

Seasonal Variations in the Grain Size Distribution and Mineral Composition of Suspended Particulate Matter of the Northern Dvina River

The paper presents the first results of a study of seasonal variations in the grain size distribution and mineral compositions of suspended particulate matter (SPM) of the Northern Dvina River. The SPM samples were collected every month during 2016–2017 at the outlet of the Kuznetchiha arm to Dvina Bay of the White Sea. The grain size fractions were separated by Petelin’s water-mechanical method with retention of fractions for subsequent analyses using an electron microscope, energy-dispersion microanalyzer, and X-ray difractometer. The results demonstrated that the pelitic and subcolloidal fractions predominated in the grain size distribution of river SPM, with subordinate coarser fractions. Seasonal variations in the SPM concentration and the total amount of detrital and clay minerals are influenced by river water discharge and achieved a maximum in high water periods (spring flood and partly at the end of summer–autumn heavy rains). The subcolloidal fraction in the March sample stands out in the fine fraction distribution. Its share in this sample was the highest among these fractions throughout the year. The reason is probably related to the highest content of fine dispersed detrital minerals in the fraction. The question of why this is encountered only in March remains open.

Particles Released by Abused Prismatic Ni-rich Automotive Lithium-ion Batteries

The particulate matter released by lithium-ion batteries during eruption and combustion caused by thermal runaway may contain heavy metal pollution elements. The aim of this study is to reveal four heavy metal element content and size distribution of particulate matter released by abused prismatic Ni-rich automotive lithium-ion batteries. A fully charged commercial 50 Ah Li(Ni0.6Mn0.2Co0.2)O2 cell was triggered by heating in a sealed chamber at nitrogen environment. The particulate matter with size being below 500 μm were divided into three samples using sieves. Four soil pollution elements, including nickel, copper, zinc, chromium, were detected, and sizes were analyzed. The results show that all these four elements are found, and nickel and copper are found in all samples. Among the four elements, Ni had the largest mass percentage, followed by Cu, Zn and Cr. These particulate matter account for 1.7% of the cell mass, with the minimum size and median size being approximately 1.45 μm and 162.9 um. The element content reveals the pollution from LIBs and the size distribution provides a basis for the design of the particle filter pore.

Concentration and size distribution of particulate matter in a new aviary system for laying hens in China

ABSTRACTParticulate matter (PM) from poultry production facilities may strongly affect the health of animals and workers in the houses, and PM emitted to the ambient air is an important pollution source to the surrounding areas. Aviary system is considered as a welfare friendly production system for laying hens. However, its air quality is typically worse as compared with conventional cage systems, because of the higher PM concentration of indoor air and other airborne contaminants. Furthermore, PM’s physical property, which has a direct impact on the penetration depth into the lungs of the birds and humans, is largely unknown for the aviary system. Therefore, a systematic method was utilized to investigate the characteristics of particles in the aviary house with large cage aviary unit system (LCAU) in Beijing, China. For the field measurements, three measuring locations were selected with two inside and one outside the house with LCAU to continuously monitor PM concentrations and collect the samples for particle size distribution (PSD) analysis. Results showed that PM2.5, PM10, and total suspended particulate (TSP) concentrations averaged at 0.037 ± 0.025 mg/m3, 0.42 ± 0.10 mg/m3, and 1.92 ± 1.91 mg/m3, respectively. Particle concentrations increased from October to December due to less ventilation as the weather got colder, and were generally affected by stocking density, ventilation rate, birds’ activities, and housing system. Meanwhile, indoor PM2.5 concentration was easily impacted by the ambient air quality. Mass median diameter (MMD) and mass geometric standard deviation (MGSD) of the TSP during the measurement were 18.92 ± 7.08 μm and 3.11 ± 0.31, respectively. Count median diameter (CMD) and count geometric standard deviation (CGSD) were 1.94 ± 0.14 μm and 1.48 ± 0.08, respectively. Results indicated that the aviary system can attain a good indoor condition by suitable system design and environment control strategy.Implications: Indoor PM2.5 concentration of the layer house can be significantly affected by ambient air quality when the air quality index (AQI) was larger than 100. PM2.5 and PM10 concentrations of the layer house with a LCAU system were comparable to the cage system. TSP concentration was higher, and PM size was larger than most of the cage system. System design, larger space volume, and higher ventilation rate were the main influence factors. Good indoor environment of the aviary system can be achieved through the reasonable design of the production system and appropriate environment control strategy.

Study of size-related sensitivity of surface acoustic wave sensor towards particulate matter sized particles using finite element and experimental methods

To investigate the potential of using a surface acoustic wave sensor to measure both particulate matter (PM) concentration and size distribution, a forced-vibration model of a coupled particle–SAW system with interfacial excitation was built using the finite element method. The model shows different behaviors of the coupled vibration between mass loading and elastic loading regimes. The calculation of the frequency change of a 260 MHz SAW perturbed by different sized starch particles in the elastic regime is in agreement with our previous experiment, proving the validity of the model. The impact of different parameters, including the particle size, contact size, and material, on the particle–SAW interaction was investigated for understanding the perturbation mechanism of real particles. Wheat flour and talcum powder particles were measured by SAW experimentally, resulting in positive and negative frequency change, respectively. The experiment shows that SAW has different sensitivities toward particles with different size distributions and morphologies. The size-related sensitivity property of SAW could be used for building an instrument that is capable of monitoring both PM concentration and size distribution.

Indication of size distribution of suspended particulate matter for sediment transport in the South Yellow Sea

The Yellow Sea is a key area for studying source-to-sink sediment transport systems in East China shelf seas. However, the sediment transport and dispersal patterns in the Yellow Sea are not fully understood because of the significant seasonal variation in ocean circulation. In this study, we identify the ocean circulation patterns in the South Yellow Sea based on temperature, salinity and depth data collected from 52 hydrographic stations during the winter of 2016. The mass concentrations and particle size distributions of suspended particulate matter are also determined to decipher the sediment transport pattern in the South Yellow Sea. The results show that particles from the Yellow Sea Coastal Current and Shandong Peninsula Coastal Current display a bimodal size distribution, with peaks at approximately 2.5 μm and 32–64 μm, while particles from the Yellow Sea Warm Current and residual Yellow Sea Cold Water Mass display a trimodal size distribution, with peaks at 2.5 μm, 32–64 μm and 391 μm. The fine and medium particles (<256 μm) are mainly inorganic particles, while the coarse particles (>256 μm) include organic materials. The peak at 391 μm is dominated by organic particles and reflects the influence of the Yellow Sea Warm Current in the surface layer. The Yellow Sea Warm Current enhances the nutrient and temperature conditions in the South Yellow Sea, which facilitates phytoplankton growth under appropriate light conditions. The content of inorganic particles with sizes of 64–159 μm decreases sharply in the central South Yellow Sea, which reflects the transport of suspended particulate matter from the southern study area to the central Yellow Sea mud area. The synthesized evidence suggests that the Yellow Sea Warm Current, as the main driving force, transports particles from the Jiangsu coast or the Changjiang River into the central Yellow Sea mud area in winter.

Relationship between UV Energy and Formation of Secondary Particles in Santiago de Chile

ABSTRACT Despite reduction efforts, the concentration of PM2.5 (particulate matter ≤ 2.5 µm in diameter) has remained steady or even grown slightly in Santiago, Chile, over the last few years. However, this potential increase may be due to the formation of secondary particles rather than a rise in primary emissions. Therefore, this study measured the size distribution of particulate matter with an Electrical Low Pressure Impactor (ELPI; Dekati) to investigate the generation of secondary ultrafine particles at several sites in this metropolitan area during 2013 and 2018. Little formation was detected during winter, but more activity was observed during fall, and the highest generation of these particles was found during summer, when the number of new particles between 10 and 20 nm in diameter displayed an obvious peak in the afternoon during periods of high solar radiation. Overall, no clear relationship was discerned between the secondary particle number and the UV radiation until the latter exceeded ~4.5 kJ m–2, when an almost linear correlation (R2 = 0.739) appeared. Additionally, the particle number exhibited a much lower correlation with the total solar energy, indicating that UV solar radiation plays the major role in ultrafine particle formation. However, these trends may only apply to polluted cities, which already contain elevated particulate matter concentrations. Also, the fact that secondary formation primarily occurs in Santiago during summer, when the PM2.5 level is low, confirms that large numbers of pre-existing particles inhibit the creation of new ones.

Chemisorption and physisorption of fine particulate matters on the floating beads during Zhundong coal combustion

Floating beads rich in silica-aluminum oxide are hollow glass microspheres that can be obtained from fly ash by flotation. Floating beads have the advantages of high yield, low cost and easy access in the power plants or industrial kilns and are used as the sorbent for reducing the fine particulate matter (PM) emissions during pulverized coal combustion in this work. The pulverized coals mixed with floating beads are burned in an electrically heated drop-tube furnace at 1573 K. The size distribution and yield of PM are analyzed by an electrical low pressure impactor (LPI). The results indicate that the internal mineral elements, especially Na/K, Ca, and S, form a large amount of PM during pulverized coal combustion and floating beads can efficiently reduce PM formation via chemisorption and physisorption. With floating beads addition, the yield of ultrafine mode particles (PM0.5), mainly consisted of Na/K and S, decreases by 55.76%, and the yield of central mode particles (PM0.5–7), mainly consisted of Ca, Fe and Si, decreases by 21.7%. The surface reaction (chemisorption) between mineral vapors and sorbent particles reduces the PM0.5 emissions, and PM0.5+ can be reduced by the particles colliding and coalescing (physisorption), resulting in aluminosilicates on the surface of the sorbents. The results gained from characterization tests show that floating beads have more active sites and free silicon dioxides due to the broken SiO and AlO bonds after high-temperature calcination, thereby promoting the capture of mineral vapors such as alkali metals.

Classification of flavors in cigarillos and little cigars and their variable cellular and acellular oxidative and cytotoxic responses.

Flavored tobacco products are increasing in popularity but remain unregulated, with the exception of the ban on flavored conventional cigarettes. Lack of regulation of cigarillos and little cigars allows vendors to have their own version of popular flavors, each with different chemical components. A new classification system was created for flavored cigars in order to easily communicate our results with the scientific community. To understand the physicochemical characteristics of flavored little cigars and cigarillo smoke, size distribution and concentration of particulate matter in smoke were determined. Acellular reactive oxygen species generation was measured as an indirect measurement of the potential to cause oxidative stress in cells. In addition, cigarillo smoke extract treatment on bronchial epithelial (Beas-2b) cells were assessed to determine the flavor-induced cellular toxicity. Flavored cigars/cigarillos showed significant variability in the tested parameters between flavors as well as brands of the same flavor, but most of the cigars showed higher potential of generating oxidative stress, than research grade cigarettes. Flavored cigars produced maximum particle concentrations at 1.0μm and 4.0 μm compared with 3R4F reference research cigarettes. A differential cytotoxic response was observed with cigarillo smoke extract treatments, with "fruits/candy" and "drinks" being the most toxic, but were not more cytotoxic than smoke from cigarettes. These cigarillos with flavors must be well characterized for toxicity in order to prevent adverse effects caused by exposure to flavor chemicals. Our study provides insight into understanding the potential health effects of flavor-infused cigars/cigarillos and the need for the regulation of those flavoring chemicals in these products. Future research is directed to determine the flavoring toxicity of little cigars and cigarillos in vivo studies.

Bayesian Proxy Modelling for Estimating Black Carbon Concentrations using White-Box and Black-Box Models

Black carbon (BC) is an important component of particulate matter (PM) in urban environments. BC is typically emitted from gas and diesel engines, coal-fired power plants, and other sources that burn fossil fuel. In contrast to PM, BC measurements are not always available on a large scale due to the operational cost and complexity of the instrumentation. Therefore, it is advantageous to develop a mathematical model for estimating the quantity of BC in the air, termed a BC proxy, to enable widening of spatial air pollution mapping. This article presents the development of BC proxies based on a Bayesian framework using measurements of PM concentrations and size distributions from 10 to 10,000 nm from a recent mobile air pollution study across several areas of Jordan. Bayesian methods using informative priors can naturally prevent over-fitting in the modelling process and the methods generate a confidence interval around the prediction, thus the estimated BC concentration can be directly quantified and assessed. In particular, two types of models are developed based on their transparency and interpretability, referred to as white-box and black-box models. The proposed methods are tested on extensive data sets obtained from the measurement campaign in Jordan. In this study, black-box models perform slightly better due to their model complexity. Nevertheless, the results demonstrate that the performance of both models does not differ significantly. In practice, white-box models are relatively more convenient to be deployed, the methods are well understood by scientists, and the models can be used to better understand key relationships.

On-the-fly particle metrology in hollow-core photonic crystal fibre.

Efficient monitoring of airborne particulate matter (PM), especially particles with aerodynamic diameter less than 2.5 µm (PM2.5), is crucial for improving public health. Reliable information on the concentration, size distribution and chemical characteristics of PMs is key to evaluating air pollution and identifying its sources. Standard methods for PM2.5 characterization require sample collection from the atmosphere and post-analysis using sophisticated equipment in a laboratory environment, and are normally very time-consuming. Although optical methods based on analysis of scattering of free-space laser beams or evanescent fields are in principle suitable for real-time particle counting and sizing, lack of knowledge of the refractive index in these methods not only leads to inevitable sizing ambiguity but also prevents identification of the particle material. In the case of evanescent wave detection, the system lifetime is strongly limited by adhesion of particles to the surfaces. Here we report a novel technique for airborne particle metrology based on hollow-core photonic crystal fibre. It offers in situ particle counting, sizing and refractive index measurement with effectively unlimited device lifetime, and relies on optical forces that automatically capture airborne particles in front of the hollow core and propel them into the fibre. The resulting transmission drop, together with the time-of-flight of the particles passing through the fibre, provide unambiguous mapping of particle size and refractive index with high accuracy. The technique offers unique advantages over currently available real-time particle metrology systems, and can be directly applied to monitoring air pollution in the open atmosphere as well as precise particle characterization in a local environment such as a closed room or a reaction vessel.

Mass Concentration and Size-distribution of Atmospheric Particulate Matter in Plateau State, Nigeria

The mass concentration and size distribution of atmospheric particulate matter (PM) was measured in three major towns in Plateau state. The CW-HAT200 PM2.5, PM10 dust particle counter was used to measure the particle size in each major location within Jos, Shendam and Pankshin. The results revealed that both PM2.5 and PM10 concentration were high in morning hours in most of the measured locations. These values were however found decreasing in the afternoon. The higher value of PM2.5 and PM10 observed in the morning hours in some locations within the study area can be attributed to the high volume of motorists plying the roads during those hours. However, some locations within the study area their PM2.5 and PM10 were higher in the afternoon hours than morning hours. The PM sampling respirable dust sampler (AMP460NL model) was placed on the elevated platform of 1.5 m high and 20 cm away from obstacles in order to avoid any obstruction of the air from tall buildings and trees etc. Measurements were taken after 8-hours per location and the average air flow rate, sample time, initial and final mass of the filter paper were used to calculate the mass concentration of the suspended particulate matter in each locations. The mass concentration of the suspended particulate matter were higher in dry season than in the rain season for all locations. This can be attributed to the dust usually experienced during the dry season on the Plateau.

How to account for particle size effects in a landscape evolution model when there is a wide range of particle sizes

Surface mining irreversibly disturbs the landscape. A first order priority is to establish an erosionally stable landscape. Soil and surface material particle size has a strong influence on soil erosion and a number of erosion models have been developed based on the relationship with particle size. Here we highlight the practicalities of assessing material particle size for a post-mining landscape. In particular, the CAESAR-Lisflood landscape evolution model (the focus here) requires a defined material particle size as input. A key feature which differentiates CAESAR-Lisflood is the ability to apply particle size data at the same resolution as the digital elevation model (DEM) representing the landform surface. Here we develop particle size distributions and demonstrate how they influence erosion for a potential post-mining landform. Field data from the site demonstrates that material particle size distribution changes little over a ten year period and yet a strong influence on erosion rates.

Size distribution and elemental composition of vent particles from abused prismatic Ni-rich automotive lithium-ion batteries

Abstract The lithium-ion battery (LIB) jet is often accompanied by particulate matter (PM) (e.g. spark) during vent and combustion caused by thermal runaway. These hot PM could ignite the combustible vent gases, and the settleable matter may promote water and soil pollution. The aim of this study is to reveal the statistical size distribution and elemental composition of the settleable PM released by LIBs after thermal runaway. A fully charged commercial 50 Ah Li(Ni0.6Mn0.2Co0.2)O2 cell was triggered by heating in a sealed chamber. These PM were divided into 4 samples using sieves. The sizes were analyzed and the elements were detected. The results show that these PM account for 11.20% of the cell mass. Nearly 45% of particles by mass were found to have a size less than 0.85 mm, with the median size being approximately 198 um. The main elements are carbon, nickel, cobalt, etc. The content of metallic elements is approximately 40%. The emissions also contain potentially toxic elements, including aluminum, lithium, fluorine, etc. The element species in different samples are similar, but their contents differ. The size distribution provides a basis for the design of the particle filter pore, and elemental composition reveals the pollution of LIB emissions.

Size distribution of particulate matter in runoff from different leaf surfaces during controlled rainfall processes

The presence of plant leaves has been shown to lower the risks of health problems by reducing atmospheric particulate matter (PM). Leaf PM accumulation capacity will saturate in the absence of runoff. Rainfall is an effective way for PM to “wash off” into the soil and renew leaf PM accumulation. However, little is known about how PM wash-off varies with PM size and health problems caused by particulate pollution vary with PM size. This study thus used artificial rainfall with six plant species to find out how size-fractioned PM are washed off during rain processes. Total wash-off masses in fine, coarse and large fractions were 0.6–10.3 μg/cm2, 1.0–18.8 μg/cm2 and 4.5–60.1 μg/cm2 respectively. P. orientalis (cypress) and E. japonicus (evergreen broadleaved shrub) had the largest wash-off masses in each fraction during rainfall. P. cerasifera (deciduous broadleaved shrub) had the largest cumulative wash-off rates in each fraction. Rainfall intensity had more influence on wash-off masses and rates of large particles for six species and for small particles in evergreen species, but limited effect on wash-off proportions. Wash-off proportions decreased in large particles and increased in small particles along with rainfall. The results provide information for PM accumulation renewal of plants used for urban greening.

First results on transient plasma-based remediation of nanoscale particulate matter in restaurant smoke emissions

Recent studies have shown that nanoscale particulate matter produced in commercial charbroiling processes represents a serious health hazard and has been linked to various forms of cancer and cardiopulmonary disease. In this study, we propose a highly effective method for treating restaurant smoke emissions using a transient pulsed plasma reactor produced by nanosecond high voltage pulses. We measure the size and relative mass distributions of particulate matter (PM) produced in commercial charbroiling processes (e.g., cooking of hamburger meat) both with and without the plasma treatment. Here, the plasma discharge is produced in a 3” diameter cylindrical reactor with a 5–10 ns high voltage (17 kV) pulse generator. The distribution of untreated nanoparticle sizes is peaked around 125–150 nm in diameter, as measured using a scanning mobility particle sizer (SMPS) spectrometer. With plasma treatment, we observe up to a 55-fold reduction in relative particle mass and a significant reduction in the nanoparticle size distribution using this method. The effectiveness of the nanoscale PM remediation increases with both the pulse repetition rate and pulse voltage, demonstrating the scalability of this approach for treating particulate matter at higher flow rates and larger diameter reactors.