Impact Of Fine Particles Research Articles

Erosion behaviour of cold sprayed stainless-steel coatings for civil infrastructures: An energetic approach

Along with corrosion, erosion is one of the main causes of damage to civil infrastructures. The continuous impact of fine particles carried by the air produces a deterioration in the elements of these structures. When this damage is significant, these elements are replaced by new ones. In this work, the possibility of extending the useful life of these components by spraying coatings on the damaged areas is proposed. In this sense, repair techniques such as cold spray deposition are possibilities for this purpose. Therefore, this study focuses on evaluating the erosion behaviour of stainless-steel coatings deposited on structural steel. In addition, the erosion results have been correlated with the model proposed by Hutchings, and an energetic interpretation of the erosion process through this model has been proposed. To carry out this study, stainless steel coatings have been deposited on carbon steel substrates to improve their resistance to corrosion. Different spraying temperatures, from 800 °C to 1100 °C, combined with different pressures of the carrier gas, from 40 to 70 bar, have been analysed. The elastic moduli of the coatings, and their stress-strain curve, have been determined by depth sensing indentation tests with Berkovich and spherical tips, respectively. Erosion tests with normal incidence have been programmed to obtain the corresponding erosion rates. From the results of this work, the optimal projection conditions of stainless steel on carbon steel substrates for the repair of civil infrastructures subjected to erosion processes could be identified.

Pollution and coronary risk: how much does it matter?

Air pollutants are a complex mixture of gaseous substances and particulate matter (PM). Each component potentially has specific harmful effects on human health, but several experimental and clinical studies have shown a strong impact of fine particles on major adverse cardiovascular events. Most of the available evidence concerns the effects of exposure to PM with a diameter of <2.5 µm (PM2.5) and the risk of developing coronary heart disease through inflammation and oxidative stress. While prolonged exposure to PM2.5 has been shown to be associated with the development of atherosclerosis and cardio-metabolic risk factors, short-term exposure has instead proved to be a trigger for acute coronary events, and especially in subjects with pre-existing coronary artery disease. As such, environmental PM2.5 is a major risk element for global public health. This underlines on the one hand not only the need to adopt and encourage preventive measures especially for individuals with a higher risk profile but also to practice environmental policies that are effective in promoting the reduction of exposure to pollutants.

Damping performance of particle dampers with different granular materials and their mixtures

A particle damper is a passive vibration control technology that utilizes the high damping properties of granular materials for reducing the vibration amplitude of a structure over a wide frequency range. Energy dissipation of particle damper is a highly nonlinear and complex physical phenomenon [1]. Previous studies have shown that the damping mechanism of a particle damper depends on several factors, like particle size and shape, granular material, filling ratio, and the number of particles [2–5]. Out of these parameters, the type of granular material used in the particle damper plays a major role in reducing the vibration amplitude of a mechanical structure. Therefore, the current contribution aims to investigate the influence of 20 different granular materials on vibration attenuation. The granular materials under investigation are subdivided into two major groups, namely: soft particles, like rubber granulate, and hard particles, like steel balls. Furthermore, this paper proposes a hybrid particle damper in which two different types of granular material mixtures are used, i.e. a particle damper in which for instance soft particles are mixed with hard particles. Moreover, in this contribution, fine particles, like rubber powder are mixed with hard granular materials like lead shot, which can be seen as an extension of the fine particle impact damper concept [6]. The humidity-dependent behavior of particle dampers is also another important issue, which is addressed in this paper. To investigate the vibration attenuation efficiency of all the granular materials and their mixtures including the humidity-dependent behavior, a laser scanning vibrometer device is used. Generally, the relationship between the vibration response and the granular material mass is rarely addressed in the literature, which can restrict the industrial application of particle dampers. Hence, the additional mass of the granular material is also a focus of this paper. The experimental investigation shows that the vibration response of the test specimen is significantly lower for particles with lower densities in the low-frequency range. Furthermore, an excellent damping efficiency can be also observed for the particle damper with a granular material mixture. The results obtained in this study are not restricted to any special structure and can be implemented in several industrial applications, where vibration and noise attenuation plays a major role, like automotive, aerospace, wind turbine, medical technology, mining, etc.

The Role of Fine Particles That Pollute Ambient Air In Atherosclerosis Pathogenesis: A Literature Review

Background. Atmospheric air pollution with fine particles (PM 2.5) is one of the global challenges having an impact on the disease rate, mortality, and disability of the earth’s population. The optimal content of PM2.5 in the air is &lt; 10 micrograms/m3 (according to WHO), however, this concentration is not completely safe. Currently the impact of fine particles that pollute ambient air on the progression of atherosclerosis and cardiovascular diseases (CVD) is being actively studied. Pathogenetic mechanisms enabling fine particles to partake in atherogenesis are being studied. Understanding specific fundamental mechanisms which underpin PM 2.5-induced atherogenesis allows to improve prevention-care intervention aimed to mitigate the negative impact of PM 2.5 on pathogeny of atherosclerosis and CVD. Objective. Study of the impact of fine particles polluting ambient air on the development and progression of atherosclerosis and CVD, as well as discussion of the main pathogenetic mechanisms that underpin this phenomenon. Methods. PubMed/Medline and Embase databases have been used for searching and analyzing modernday literature. We looked at the terms «fine particles», and «PM 2.5» in combination «atmospheric air» with «atherosclerosis». The search for literary sources has been carried out over the past 15 years. Results. Many experimental and clinical studies prove the connection between fine particles (PM 2.5) polluting ambient air and the risk of atherosclerosis progression and further CVD progression, all the way through to the increased risk of unfavorable cardiovascular events (acute myocardial infarction, cerebral vascular accidents) in persons inhabiting polluted areas. PM 2.5-induced atherosclerosis is underpinned by the following pathogenetic mechanisms: Induction of oxidative stress and enhancement of inflammatory reactions, progression of endothelial dysfunction, as well as dysfunction of vegetative nervous system, and imbalance of coagulative blood system.

Dynamics of particle retention and physiology in Euonymus japonicus Thunb. var. aurea-marginatus Hort. with severe exhaust exposure under continuous drought

Frequent drought events and particulate matter pollution from vehicular exhaust seriously affect urban plant growth and provisioning of ecological services. Yet, how plants respond physiologically and morphologically to these two combined stressors remains unknown. Here, we assessed particle retention dynamics and plant morphology and physiology of Euonymus japonicus Thunb. var. aurea-marginatus Hort. under continuous drought with severe exhaust exposure. Our results showed that continuous drought insignificantly lowered particle retention in each of three size fractions by 1.02 μg·cm−2 on average in the first 28 days, but significantly lowered total particle retention by 35.75 μg·cm−2 on the 35th day. We observed evident changes in morphology, leaf mass per area (LMA), pigments, gas exchange in all stressed plants. Compared with single stress, combined drought and pollution caused earlier yellowing and shedding of old leaves, significantly lowered LMA by 1.21 mg·cm−2, caused a greater decline in pigments and net photosynthetic rate (Pn). Large particles may mainly explain pigment reduction, lower weekly LMA increases, and stomatal restriction, while coarse particles may be the main drivers of the decline in Pn. Continuous drought mediated the influence of all three particle sizes on some parameters, such as weakening the impact of total particles on LMA, strengthening the impact of fine particles on photosynthesis. Our findings suggest that drought accelerates the physiological responses of plants to exhaust pollution. Under controlled severe exhaust pollution conditions, the optimal time to maintain high particle retention during continuous drought without decline in physiological conditions for E. japonicus var. aurea-marginatus was 14 days. Some additional interventions after 14 days (it could be postponed appropriately under field conditions) may help ensure healthy growth of plants and retention of particulate matter.

Autophagy changes in lung tissues of mice at 30 days after carbon black-metal ion co-exposure.

ObjectivesAccumulating studies have investigated the PM2.5‐induced pulmonary toxicity, while gaps still remain in understanding its toxic mechanism. Due to its high specific surface area and adsorption capacity similar to nanoparticles, PM2.5 acts as a significant carrier of metals in air and then leads to altered toxic effects. In this study, we aimed to use CBs and Ni as model materials to investigate the autophagy changes and pulmonary toxic effects at 30 days following intratracheal instillation of CBs‐Ni mixture.Materials and methodsGroups of mice were instilled with 100 µL normal saline (NS), 20 µg CBs, and 4 µg Ni or CBs‐Ni mixture, respectively. At 7 and 30 days post‐instillation, all the mice were weighed and then sacrificed. The evaluation system was composed of the following: (a) autophagy and lysosomal function assessment, (b) trace element biodistribution observation in lungs, (c) pulmonary lavage biomedical analysis, (d) lung histopathological evaluation, (e) coefficient analysis of major organs and (f) CBs‐Ni interaction and cell proliferation assessment.ResultsWe found that after CBs‐Ni co‐exposure, no obvious autophagy and lysosomal dysfunction or pulmonary toxicity was detected, along with complete clearance of Ni from lung tissues as well as recovery of biochemical indexes to normal range.ConclusionsWe conclude that the damaged autophagy and lysosomal function, as well as physiological function, was repaired at 30 days after exposure of CBs‐Ni. Our findings provide a new idea for scientific assessment of the impact of fine particles on environment and human health, and useful information for the comprehensive treatment of air pollution.

CFD–DEM Simulations of Seepage-Induced Erosion

Increases in seepage force reduce the effective stress of particles and result in the erosion of particles, producing heave failure and piping. Sheet piles/cutoff walls are often employed in dams to control the seepage. In this study, a computational fluid dynamics solver involving two fluid phases was developed and coupled with discrete element method software to simulate the piping process around a sheet pile/cutoff wall. Binary-sized particles were selected to study the impact of fine particles on the mechanisms of seepage. The seepage phenomenon mainly appeared among fine particles located in the downstream side, with the peak magnitudes of drag force and displacement occurring around the retaining wall. Based on the particle-scale observations, the impact of seepage produced a looser condition for the region concentrated around the retaining wall and resulted in an anisotropic condition in the soil skeleton. The results indicate that heave behavior occurs when the drag force located adjacent to the boundary on the downstream side is larger than the corresponding weight of the bulk soil.

Impact of fine particles on the rheological properties of uranium dioxide powders

This study aims at characterizing the rheological properties of uranium oxide powders for nuclear fuel pellets manufacturing. The flowability of these powders must be compatible with a reproducible filling of press molds. The particle size distribution is known to have an impact on the rheological properties and fine particles (<100 μm) are suspected to have a detrimental effect. In this study, the impact of the particle size distribution on the rheological properties of UO2 powders was quantified, focusing on the influence of fine particles. Two complementary approaches were used. The first approach involved characterizing the powder in a static state: density, compressibility and shear test measurements were used to understand the behavior of the powder when it is transitioned from a static to a dynamic state (i.e., incipient flow conditions). The second approach involved characterizing the behavior of the powder in a dynamic state. Two zones, corresponding to two characteristic behaviors, were demonstrated for both types of measurements. The obtained results showed the amount of fines should be kept below 10 %wt to ensure a robust mold filling operation (i.e., constant mass and production rate).

Fine particle environmental pollution and cardiovascular diseases

Air pollution affects 90% of the world's population and has caused 9 million deaths in 2015, becoming the most important cause of premature deaths in the world. Exposure to fine particulate matter, a major component of urban air pollution, has been associated with an increase in cardiovascular risk and associated mortality. Impact of fine particles on the cardiovascular system includes inflammation, activation of prothrombotic pathways, oxidative stress, vascular dysfunction and remodeling, and neurological dysfunction. Genetic and epigenetic factors might also increase the susceptibility to air pollution. Consequently, epidemiologic studies have identified correlations between air particulate matter concentrations and acute coronary events, ischemic cardiomyopathy, acute heart failure, and stroke. Interestingly, these effects are present even for fine particulate matter concentrations below current US and EU regulatory standards, and seems to be more harmful in the most fragile population such as low-income or elderly subjects, or patients with previous cardiovascular disease.This review aims to summarize recent data on the pathophysiology and epidemiology of cardiovascular disease after particulate matter exposure. It will also discuss potential strategies to reduce the impact of air pollution on current and future populations' health.

Classification of Indoor Environment 2018 and Updated Criteria of RTS Environmental Classification

The Finnish Society of Indoor Air Quality and Climate (FiSIAQ) introduced over twenty years ago in 1995 a Classification of Indoor Climate, Construction Cleanliness, and Finishing Materials. After two revised versions, the fourth edition Classification of Indoor Environment was published on May 2018. Based on the criteria set in the classifications, The Building Information Foundation RTS sr started M1-labelling of building products in 1996, named Emission Classification of Building Materials and Cleanliness Classification of Air-handling Components. Indoor air quality and instruments in improving all the sectors to concern are in great importance in Finland. First part of The Classification of Indoor Environment 2018 (CIE 2018) includes new Requirements for Technical Target Values. The other part, Guidance for design and Construction, includes surface structural design, construction site design, Classification of Construction and Construction Work Cleanliness (P1), Classification of Building Materials (M1), Cleanliness Class of Air-handling components (M1) and instructions for designing mechanical systems for buildings. The main changes in the 2018 edition are revised target values for indoor operative temperature, inclusion of a PM2.5 criteria, revision of some acoustical target values and revision of recommended outdoor air flows. Regarding thermal comfort, the target values of the individual indoor climate, S1, will be slightly more demanding than the targets of the S2, good indoor climate, class. The criteria for particulate matter, PM2.5, has been included due to the significant health impact of fine particles. The targets for acoustic environment in offices have been revised to reflect the importance of speech transmission. The recommended outdoor air flows follow the principles of EN15251-2007, considering the common usage of very low-emitting M1-class materials in Finland. The outdoor air flow rates have also been aligned with the recently changed building code values. Companies have developed low-emitting building materials, fixtures, furniture and HVAC-devices during the years to meet the requirements. There are almost 5200 M1-classified low emitting building materials, fixture, furniture and HVAC-devices at the moment (May 2019). The Classification of Indoor Environment 2018 (classes S1, S2) and sub-classifications (P1) and (M1) are integrated part of the new Finnish environmental classification system for building processes called RTS Environmental Classification launched in the spring 2017 and updated in September 2018. The Classification of Indoor Environment has been used in multiple office and residential construction projects during the years. By integrating the CIE 2018 requirements to the RTS 2018, third-party audit and certification of the whole construction project is possible. Therefore, the continuous improvement will be one considerable option.

An in vitro model to evaluate the impact of environmental fine particles (PM0.3-2.5) on skin damage

Exposure to airborne particulate matter (PM) has significant effects on human health mainly leading to cardio-respiratory diseases. However very few data are available regarding the impact of PM on the skin, so to better understand the impact of fine particle (PM0.3-2.5) on both inflammatory response and epidermal structure, we exposed a reconstructed human epidermis (RHE) to several doses of PM collected in Cotonou (Benin, West Africa). After 24 h of exposure, inflammatory response, histological observations, and gene expression related to oxidative stress, antioxidant defense and structural damages were determined. No PM-linked changes in tissue morphology or membrane integrity were observable. PM was however cytotoxic in a dose dependent manner. An inflammatory response appeared as shown by the increase in IL-1α and IL-8 cytokine productions. PM also induced oxidative stress, leading to an increase in 4-HNE immunostaining and to the up-regulation of HMOX1, MT1G and MT1E. Finally, PM had a negative impact on fundamental skin functions such as tissue anchorage, cell differentiation, cornification / skin desquamation and apoptosis. Our data show that airborne fine particles have an adverse effect on skin integrity, most probably leading to accelerated ageing.

A spring-supported fine particle impact damper to reduce harmonic vibration of cantilever beam

Spring-supported fine particle impact damper which integrates the effects of elastic deformation and the plastic deformation performs excellently on the attenuation of vibration in cantilever beam....

Impact of fine particles on the direct current electric field of the conductor due to corona discharge

Corona-generated ionized field is an essential electromagnetic parameter of high voltage direct current transmission lines. In order to investigate the impact of atmospheric fine particles on the DC ionized field, distributions of the ground-level ionized field and ion current density were measured under various air contamination extents in a wire-to-ground platform. The fine particles were generated from burning incense. Measurement results show that the magnitude of ground-level ionized field may increase approximately by 20% when particles in the order of 102 μg m−3 exist in air. Restriction effect on the ionized field by using grounded shielding lines was also examined.

Metal-bearing fine particle sources in a coastal industrialized environment

Fine (<2.5μm), submicron (<1μm) and ultrafine (<100nm) atmospheric particles were collected during a 3-weeks campaign in a heavily industrialized area and physically and chemically characterized in order to determine their main sources. As a basis of comparison, the present one-year average EU limit value (25μg·m−3) and the WHO recommendation for PM2.5 (10μgm−3) were regularly exceeded during this campaign. Submicron particles (PM1) account for 55 to 70% of PM2.5 mass concentrations. A bi-modal size distribution, centered on 0.4 and 2.0μm, suggests two types of emissions: high temperature processes that liberate primary or secondary submicron particles and mechanical procedures in open air, or local traffic, which lead to the emission of coarser particles (>1μm). The trace elements As, Cd, Ni, Pb, Sb, V and Zn, characteristics of the local industrial activities display 60% to 85% of their mass in the submicron and ultrafine fractions and appear highly enriched, by reference to the crustal source. High atmospheric pressure periods, corresponding to northeasterly winds, induce the highest contributions of metalworking emissions and the highest PM2.5 concentrations (32.5±11.9μg·m−3). A Principal Component Analysis of the dataset produces 7 factors associated to metallurgy-, steelworks-, oil processing-, coal combustion-, neighboring traffic-, dust resuspension- and sea salt-sources, that explain the obtained concentrations. A Multiple Linear Regression Analysis confirms that Fe-Mn alloy refining, iron- and steel-making are the main sources (>40%) controlling metal concentrations in PM2.5. Less predictably, resuspended dust and fresh/aged sea salts are also significant contributors (≈20%). Considering the related health hazards, authorities should pay more attention to the exposure of people living in this area and the possible impact of fine particles in terms of public health.

A study of aerosol optical properties during ozone pollution episodes in 2013 over Shanghai, China

Aerosol optical property is essential to the tropospheric ozone formation mechanism while it was rarely measured in ozone-rich environment for a specific study. With the retrieved products of the sun-photometer, a comparative investigation was conducted on aerosol optical depth (AOD), single scattering albedo (SSA) and size distribution during ozone-polluted episodes and clean background. Contrary to expectations, aerosol loading was found to be positively-correlated with ozone concentration: daily averaged AOD at 500nm in ozone episodes (~0.78) displayed 2.4 times higher than that in clean days (~0.32). Large Ångström exponent (~1.51) along with heavy aerosol loading indicated a considerable impact of fine particles on optical extinction. The dynamic diurnal fluctuation of these parameters also implied a complex interaction between aerosols and photo-chemical reactions. The bimodal lognormal distribution pattern for aerosol size spectra exhibited in both ozone-polluted and clean days. The occurrence of maximum volume concentration (~0.28) in fine mode (radius <0.6μm) was observed at 3p.m. (local time), when ozone was substantially generated. Pronounced scattering feature of aerosol was reproduced in high-concentration ozone environment. SSA tended to increase continuously from morning (~0.91 at 440nm) to afternoon (~0.99), which may be associated with secondary aerosol formation. The scattering aerosol (with moderately high aerosol loading) may favor the ozone formation through increasing solar flux in boundary layer. Utilizing the micro-pulse lidar (MPL), a more developed planet boundary layer (PBL, top height ~1.96km) was discovered during ozone-polluted days than clean condition (~1.4km). In episodes, the maximum extinction ratio (~0.5km−1) was presented at a height of 1.2km in the late afternoon. The humidity profile by sounding also showed the extreme value at this altitude. It suggested that optical extinction was mainly attributed to the aerosol in middle PBL, where the intense photochemical reactions and hydroscopic growth may occur.

An Experimental Investigation on the Influence of Temperature on the Normal Impact of Fine Particles with a Plane Surface

This study investigated the rebound behavior of SiO2 particles normally impacting a planar surface under different temperature conditions. The system has been characterized for an aerosol inlet temperature range of 20–190 °C, flow velocities of 0–20 ms−1, and an impaction surface temperature range of 20–140 °C. For the first time, while keeping the same temperature gradient from the high- to low-temperature regions, the influences of varying temperature on the rebound behavior of SiO2 particles normally impacting a plane surface were examined. At increased temperatures, the plastic deformation increases and the coefficient of restitution reduces. The critical velocity is between 0.542 and 0.546 m/s under condition 1 (the carrier gas temperature (Tg) and the impaction surface temperature (TW) remain at room temperature of 20 °C), which increases to between 0.829 and 0.847 m/s under condition 4 (Tg and TW remain at temperatures of 190 °C and 140 °C, respectively). The experimental results show that the critical velocity increases with increasing temperature.

Impact of fine particles in ambient air on lung cancer

Recently, the International Agency for Research on Cancer (IARC) has classified outdoor air pollution and the particulate matter component of outdoor air pollution as class I carcinogen. Air pollution is consistently associated with lung cancer in epidemiologic and experimental studies. The IARC assessment is specifically designed as hazard identification, and it does not quantify the magnitude of the cancer risk. This article addresses the magnitude of the lung cancer risk in the population due to ambient air pollution exposure.

SURFACE QUALITY ENRICHMENT USING FINE PARTICLE IMPACT DAMPER IN BORING OPERATIONS

Boring operations are challenging owing to limited process performance due to inherent tool overhang a nd resulting vibrations. The tool vibrations can be suppressed with insertion of suitable damping methodology. The fine particle im pact damping offers a better damping method. Due to its conceptual simplicity, p otential effectiveness over a wide frequency range, temperature and degradation insensitivity and cost-effectiveness, particle damp ing is an attractive passive damping. The fine particles embedded within small hole in a vibrating structure to dissipate the exciting energy thereby damping the vibrations. The present work, investigates the improvement of surface quality of boring operation using fine particle impact damper. Substantial impr ovement of surface quality of the internally machined surfaces has been noticed i n the experiments.

Characteristics of visibility and particulate matter (PM) in an urban area of Northeast China

The visibility data from 2010 to 2012 were obtained at Shenyang in Northeast China and the relations between visibility, PM mass concentration and meteorological variables were statistically analyzed. These results demonstrate that the monthly–averaged visibility over Shenyang was higher in March and September with values of approximately 19.0±4.3 km and 17.1±4.3 km, respectively. Low visibility over Shenyang occurred in January at approximately 11.0±4.7 km. Among the meteorological variables considered, wind speed was the main meteorological factor that influenced visibility and PM mass concentrations. The relation between visibility and PM indicates that fine particles are already a main source of pollutants, the existence of which is the most important factor in the deterioration of visibility in an urban area of Northeast China. The study also shows an obvious diurnal variation and weekend effects of visibility and PM, which are mainly caused by human activities. Results of this study highlight the significant impact of fine particles on air pollution and visibility in an urban area of Northeast China.

Modeling the fine particle impact damper

The fine particle impact dampers (FPIDs) using plastic deformation of fine particles as irreversible energy sink can exhaust much more vibration energy than single mass impact dampers (SMIDs) and thus can work well in low frequency domain. A numerical model is set up in this paper to capture the complex physics involved in the FPID. Experimental results on a cantilever beam with FPID showed good agreement with the model predictions. We show that in all cases the damping performances of the FPID are much better than that of the SMID, and fine particles enrolled in the FPID play a key role in vibration energy dissipation. The damper clearance and the mass ratio are two important parameters for the damping ability of the FPID, for which an optimal combination of them exists targeting the largest damping ability.