Scanning Mobility Particle Sizer Spectrometer Research Articles

Effects of isoprene on the ozonolysis of Δ3-carene and β-caryophyllene: Mechanisms of secondary organic aerosol formation and cross-dimerization

Elucidating the mutual effects between the different volatile organic compounds (VOCs) is crucial for comprehending the formation mechanism of atmospheric secondary organic aerosols (SOA). Here, the mixed VOCs experiments of isoprene and Δ3-carene/β-caryophyllene were carried out in the presence of O3 using an indoor smog chamber. The suppression effect of isoprene was recognized by the scanning mobility particle sizer spectrometer, online vacuum ultraviolet free electron laser (VUV-FEL) photoionization aerosol mass spectrometry, and quantum chemical calculations. The results indicate that the suppression effect of isoprene on the ozonolysis of Δ3-carene and β-caryophyllene shows fluctuating and monotonous trends, respectively. The carbon content of the precursor could be the main factor for regulating the strength of the suppression effect. Plausible structures and formation mechanisms of several new products generated from the single VOC precursor and VOC-cross-reaction are proposed, which enrich the category of VOC oxidation products. Meanwhile, a new dimerization mechanism of the RO2 + R'O2 reaction is suggested, which offers an intriguing perspective on the gas phase formation process of particle phase accretion products. The present findings provide valuable insights into clarifying the pivotal roles played by isoprene in the interplay between different VOCs and understanding of SOA formation mechanisms of VOC mixtures, especially nearby the emission origins.

The role of snow in scavenging aerosol particles: A physical-chemical characterization

The below cloud scavenging of aerosols by snow has been analysed in León (NW Spain). Six snow events were registered over the course of one year of study. Ultrafine and accumulation aerosol particles were measured using a scanning mobility particle sizer spectrometer, while hydrometeors were characterized using a disdrometer. Furthermore, the chemical composition of the melted snow-water samples (soluble and insoluble fractions) was analysed.The scavenging coefficient (λ) showed a great variability among events. An effective washing of particles was observed during the first 30 min of snowfall. The mean change in the scavenging efficiency (%ΔC) of particle number concentration (PNC) and λ coefficient during this time interval were: i) nucleation mode: 36.3 % and 3.02 · 10−4 s−1; ii) Aitken mode: 30.4 % and 2.37 · 10−4 s−1 and iii) accumulation mode: 22.4 % and 1.77 · 10−4 s−1. The range of particle sizes that is less efficiently scavenged by snowfall was observed between 400 and 600 nm. When analyzing the whole snow event, an increase of PNC was observed. Two possible explanations underlie this behaviour: it could be caused by changes in air masses or by the resuspension of aerosol particles scavenged by snowflakes upon reaching the ground. A clear relationship was observed between Ca2+, SO42− and NO3− concentrations of aerosol particles before the snow event and the concentrations registered in the melted snow-water.The largest and smallest changes in aerosol number concentrations were caused by snowflakes of 3 and 6 mm in diameter, respectively. The particle size distributions (PSD) were fitted to log-normal distributions and the parameters were compared before and after snowfall.

IVOC/SVOC and size distribution characteristics of particulate matter emissions from a modern aero-engine combustor in different operational modes

The particulate matter (PM) of Intermediate-Volatile Organic Compounds (IVOC) / Semi-Volatile Organic Compound (SVOC) from aircraft engine emissions, despite being significant precursors of secondary organic aerosols deteriorating air quality in the vicinity of airports, have not been fully investigated at molecular level. In this study, the particulate IVOC/SVOC emissions from a rig test on a Technology of Low Emission Stirred Swirl aero-engine combustor, being operated with dual diffusion and premixed-dominant combustion modes, have been characterized via a two-dimensional gas chromatography-time of flight mass spectrometer (GC × GC-ToFMS). The IVOC/SVOC compounds, including 25n-alkanes, 15 cyclic alkanes and 13 polycyclic aromatic hydrocarbons were analyzed in this study. We found that including the premixed-dominant combustion mode at climb/takeoff conditions reduced the particulate IVOC/SVOC emissions significantly by nearly 80%, compared to using the diffusion combustion mode alone at idle/approach condition. Meanwhile, the measurements on organic PM obtained from a scanning mobility particle sizer spectrometer with a catalytic stripper demonstrated a consistent trend with the the IVOC/SVOC emissions, which were also suppressed by over 85% at climb/takeoff compared to idle/approach. The inter-relationship between the size-resolved organic PM and the speciated IVOC/SVOC emissions has been further explored, showing that the nucleation mode PM is dominated in organic PM by over 50%, in which IVOCs/SVOCs may be a significant contributor. This study expands the understanding of aviation-emitted organic particles, and suggests a path for future aero-engine development to mitigate the IVOC/SVOC emissions particularly at low power conditions. However, compared to the real aero-engine emissions, the results from rig combustor tests should be interpreted with great care, since there are still some work to be done to establish the quantitative relationship between emissions from rig combustors andthose from real engines.

Size distribution of ambient and radioactive aerosols formed by the short-lived radon progeny

The survey of ambient airborne particle size distribution is important when the deposition of radioactive particles is considered in the human lung and the assessment of radiation hazard in occupational exposures or contaminated environments. CLOR (the Central Laboratory for Radiological Protection) in cooperation with CMI (the Central Mining Institute) performed simultaneous measurements of the activity size distribution of radon progeny and ambient aerosols using different types of aerosols. Measurements were performed in a radon chamber with a volume of 17 m3, where radon was generated by a radium-226 open source, and ambient aerosols by an oil candle, vax candle, and incense sticks. Such measurements were also made in an aerosol depleted atmosphere after cleaning the chamber air by means of a high-efficiency pump and filters. The size distribution of radioactive aerosols containing radon progeny was measured by RPPSS (Radon Progeny Particle Size Spectrometer) with the measuring size ranging from 0.6 nm to approximately 2500 nm. The key parts of this device are the impaction plates and diffusion screen batteries, which collect aerosols of different sizes, and semiconductor alpha detectors which detect the activity of the collected particles. The SMPS (Scanning Mobility Particle Sizer Spectrometer) and APS (Aerodynamic Particle Sizer) were applied to evaluate the size distribution of all aerosols with sizes from approximately 3 nm to 20 μm. Based on the results obtained by these spectrometers, the activity size distributions and related dose conversion factors (DCF) were evaluated both for the exposed workers and the general population.

The effects of physical and chemical characteristics of aerosol number concentration on scattering coefficients in Nanjing, China: Insights from a single particle aerosol mass spectrometer

The physical and chemical characteristics of aerosols have a significant effect on scattering coefficients (σsp). In this research, a single particle aerosol mass spectrometer (SPAMS) and a scanning mobility particle sizer spectrometer (SMPS) were used to measure the chemical composition and size distribution of aerosol number concentration in Nanjing, China. During the observation time, the average σsp varied from 11.64 to 485.84 Mm−1, with an average of 114.16 ± 77.87 Mm−1. For relative humidity greater than 75.0%, the optical hygroscopic growth factor (f(RH)) increased rapidly, with an approximate distribution of 3.41 ± 0.78. During the night of July 15th, 2015, nitrate and sulfate increased by 5.93 and 1.32 times, respectively, compared with daytime values. The peak of the average size distribution of the aerosol number concentration during the observation period (341.0 cm−3) was located in the Aitken mode of 58.3 nm. After particle size conversion from the vacuum aerodynamic diameter to the mobility diameter, the particle size range of the aerosol mass spectrometer ranged from 138.2–723.4 nm, all of which are distributed in accumulation mode. Source apportionment revealed that secondary, biomass, and carbonaceous aerosols are the primary facilitators in 327.8–406.8 nm, accounting for 21.3%, 25.7%, and 33.3%, respectively. The fixed scattering coefficients were calculated using the Mie model, according to the source apportionment of aerosol number concentration for modifying the aerosol refractive index. From July 6th–11th, the calculation and observation results of σsp exhibit excellent consistency and a Pearson coefficient of 0.66. Therefore, the accurate size distribution of the chemical composition and source apportionment of aerosols are of great significance for the simulation of atmospheric optical scattering.

Home-made masks with filtration efficiency for nano-aerosols for community mitigation of COVID-19 pandemic

ObjectivesThe novel coronavirus disease 2019 (COVID-19) epidemic that emerged in December 2019 has rapidly evolved in recent months to become a worldwide and ongoing pandemic. Shortage of medical masks remains an unresolved problem. This study aims to investigate the filtration efficiency (FE) of home-made masks that could be used as alternatives for community mitigation of COVID-19. Study designExperimental observational analytic study. MethodsThe FE of home-made masks and medical masks (as the control) were tested under laminar flow within a scaled air duct system using nebulised NaCl aerosols sized 6–220 nm. The size-resolved NaCl aerosol count was measured using a scanning mobility particle-sizer spectrometer. Home-made masks with an external plastic face shield also underwent a splash test. In addition, the fibre structures of medical masks were studied under an electron microscope after treatment with either 75% alcohol or soap and water at 60 °C. ResultsThe FE of the home-made masks at 6–200 nm were non-inferior to that of medical masks (84.54% vs 86.94%, P = 0.102). Both types of masks achieved an FE of 90% at 6–89 nm. A significantly higher FE was achieved when one piece of tissue paper was added adjacent to the inner surface of the medical mask than medical mask alone (6–200 nm: 91.64% vs 86.94%, P < 0.0001; 6–89 nm: 94.27% vs 90.54%, P < 0.0001; 90–200 nm: 82.69% vs 73.81%, P < 0.0001). The plastic face shield prevented the home-made mask from fluid splash. The fibre structures of the external surface of medical masks were damaged after treatment with either 75% alcohol or soap and water at 60 °C. ConclusionsThe home-made masks in this study, which were made of one piece of tissue paper and two pieces of kitchen towels, layered from face to external, had an FE at 6–200 nm non-inferior to that of medical mask materials, which had a certified FE of ≥95% at 3 μm. In the current COVID-19 pandemic with the shortage of medical masks, these home-made masks combined with an external plastic shield could be used as an alternative to medical masks for community mitigation. In addition, one piece of tissue paper could be placed adjacent to the inner surface of a medical mask to prolong effective lifespan of the medical mask. These demand reduction strategies could be used to reserve medical masks for use in healthcare and certain high-risk community settings, such as symptomatic persons, caregivers and attendees to healthcare institutions.

The Influence of Graphene Oxide on Nanoparticle Emissions during Drilling of Graphene/Epoxy Carbon-Fiber Reinforced Engineered Nanomaterials

Graphene oxide (GO) nanoparticles are increasingly being used to tailor industrial composites. However, despite the advantages, GO has shown conceivable health risks and toxicity to humans and the environment if released. This study investigates the influence that GO concentrations have on nanoparticle emissions from epoxy-reinforced carbon fiber hybrid composites (EP/CF) during a lifecycle scenario, that is, a drilling process. The mechanical properties are investigated and an automated drilling methodology in which the background noise is eliminated is used for the nanoparticle emissions measurements. Real-time measurements are collected using a condensation particle counter (CPC), a scanning mobility particle sizer spectrometer (SMPS), a real-time fast mobility particle spectrometer (DMS50) and post-test analytical methods. The results observe that all three nanoparticle reinforced samples demonstrated a statistically significant difference of up to a 243% increase in mean peak particle number concentration in comparison to the EP/CF sample. The results offer a novel set of data comparing the nanoparticle release of GO with varying filler weight concentration and correlating it the mechanical influence of the fillers. The results show that the release characteristics and the influence in particle number concentration are primarily dependent on the matrix brittleness and not necessarily the filler weight concentration within the nanocomposite.

Size distribution of ambient and radioactive aerosols formed by the short-lived radon progeny

Abstract The survey of ambient airborne particle size distribution is important when the deposition of radioactive particles is considered in the human lung and the assessment of radiation hazard in occupational exposures or contaminated environments. CLOR (the Central Laboratory for Radiological Protection) in cooperation with CMI (the Central Mining Institute) performed simultaneous measurements of the activity size distribution of radon progeny and ambient aerosols using different types of aerosols. Measurements were performed in a radon chamber with a volume of 17 m3, where radon was generated by a radium-226 open source, and ambient aerosols by an oil candle, vax candle, and incense sticks. Such measurements were also made in an aerosol depleted atmosphere after cleaning the chamber air by means of a high-efficiency pump and filters. The size distribution of radioactive aerosols containing radon progeny was measured by RPPSS (Radon Progeny Particle Size Spectrometer) with the measuring size ranging from 0.6 nm to approximately 2500 nm. The key parts of this device are the impaction plates and diffusion screen batteries, which collect aerosols of different sizes, and semiconductor alpha detectors which detect the activity of the collected particles. The SMPS (Scanning Mobility Particle Sizer Spectrometer) and APS (Aerodynamic Particle Sizer) were applied to evaluate the size distribution of all aerosols with sizes from approximately 3 nm to 20 μm. Based on the results obtained by these spectrometers, the activity size distributions and related dose conversion factors (DCF) were evaluated both for the exposed workers and the general population.

Cluster analysis of urban ultrafine particles size distributions

Measurements of particle size distribution was made in one location of an urban area in the period January–September/2015 in order to understand the sources and mechanisms influencing ultrafine particle (UFP) number concentrations (PNC2.5-250) using a Scanning Mobility Particle Sizer Spectrometer (SMPS). k-means cluster analysis was applied to interpret the sources, temporal and spatial trends of UFP. Eight clusters were obtained. Main PSD patterns of each cluster, mean concentration of other air pollutants tracing specific sources and processes, and that of meteorological variables, as well as the hourly and seasonal frequencies of occurrence were used to support the interpretation of their origin. Thus, clusters were attributed to traffic rush hours, midday summer new particle formation, diurnal new particle formation and growth, growth of nucleated and other urban particles, urban background, regional and urban background and regional and urban background on cold nights. Many PSDs of the clusters were dominated by nucleation mode particles: midday nucleated fresh particles, photochemically induced (NPF); diurnal nucleation episodes (NPF2); growth of nucleated particles in nocturnal aging (GNPF). Origins of the clusters were related to local/regional sources (mostly traffic and biomass burning), atmospheric processes (photochemical formation and growth) and urban/regional background. Results clearly shows that traffic is a major UFP source in nucleation mode and occurred in higher concentrations in winter (08:00 to 12:00 h) during traffic rush hours, and at night. Photochemical nucleation occurred with a relatively low frequency but yielding very high PNC.

Particle size distribution of the radon progeny and ambient aerosols in the Underground Tourist Route “Liczyrzepa” Mine in Kowary Adit

Central Laboratory for Radiological Protection, in cooperation with Central Mining Institute performed measurements of radon concentration in air, potential alpha energy concentration (PAEC), particle size distribution of the radon progeny and ambient aerosols in the Underground Tourist-Educational Route “Liczyrzepa” Mine in Kowary Adit. A research study was developed to investigate the appropriate dose conversion factors for short-lived radon progeny. The particle size distribution of radon progeny was determined using Radon Progeny Particle Size Spectrometer (RPPSS). The device allows to receive the distribution of PAEC in the particle size range from 0.6 nm to 2494 nm, based on their activity measured on 8 stages composed of impaction plates or diffusion screens. The measurements of the ambient airborne particle size distribution were performed in the range from a few nanometres to about 20 micrometres using Aerodynamic Particle Sizer (APS) spectrometer and the Scanning Mobility Particle Sizer Spectrometer (SMPS).

Simultaneous Measurements of Nanoaerosols and Radioactive Aerosols Containing the Short-lived Radon Isotopes.

The activity size distribution of the Equilibrium-Equivalent Concentration (EER) of 222Rn is one of the most important parameters for the estimation of radiation dose by inhalation of radon decay products. A series of measurements of the EER activity size distribution were performed by the screen diffusion battery in Radon-Aerosol chamber (10 m3) at the National Institute for Nuclear, Chemical, and Biological Protection (SUJCHBO). These measurements were performed at different levels of radon concentration. For this study, the Graded Screen Array Diffusion Battery (GSA DB), developed by the SUJCHBO (based on Earl Knutson and Robert F Holub design), consists of 10 screens and backup filter used to collect all particles that penetrated the screens. The measuring range of this GSA DB allows measuring the radioactive nanoaerosols in the size range from 0.5 to 100 nm. The Earl Knutson algorithm was used for EER activity size distribution evaluation. The results of EER activity size distribution were subsequently compared with the aerosol particle size distribution measured by Scanning Mobility Particle Sizer Spectrometer (SMPS 3936 N, TSI Inc., MN, USA).

The effect of nanosilica (SiO2) and nanoalumina (Al2O3) reinforced polyester nanocomposites on aerosol nanoparticle emissions into the environment during automated drilling

ABSTRACTThe aim of this study is to investigate the effect nanosilica and nanoalumina has on nanoparticle release from industrial nanocomposites due to drilling for hazard reduction whilst simultaneously obtaining the necessary mechanical performance. This study is therefore specifically designed such that all background noise is eliminated in the measurements range of 0.01 particles/cm3 and ±10% at 106 particles/cm3. The impact nano-sized SiO2 and Al2O3 reinforced polyester has on nanoparticle aerosols generated due to drilling is investigated. Real-time measurement was conducted within a specially designed controlled test chamber using a condensation particle counter (CPC) and a scanning mobility particle sizer spectrometer (SMPS). The results show that the polyester nanocomposite samples displayed statistically significant differences and an increase in nanoparticle number concentration by up to 228% compared to virgin polyester. It is shown that the nanofillers adhered to the polyester matrix showing ...

Sensitivity analysis of fuel types and operational parameters on the particulate matter emissions from an aviation piston engine burning heavy fuels

Currently, general aviation aircrafts have growing demand for internal combustion engines burning heavy fuels (i.e. diesel or kerosene) due to the concerns on the safety, costs and availability of aviation gasoline (AVGAS). The application of heavy fuels requires the change of combustion mode from pre-mixed mode to diffusion mode, which will inevitably increase the particulate matter (PM) emissions as incomplete combustion products. In this work, the size-resolved number concentrations of the PM emissions emitted from an internal compression ignition engine burning diesel, RP3 and Fischer-Tropsch (FT) kerosene were studied by a Scanning Mobility Particle Sizer Spectrometer (SMPS). An opacimeter was utilized to measure the opacity of the soot emissions (linearly related to the soot mass), which was in consistent with the SMPS data. Results demonstrated that the FT fuel produced the lowest PM emissions due to absence of sulfur and aromatic contents. Diesel turned out to have the greatest ‘sooting’ tendency and produced more accumulation mode PM in number than FT fuel by a factor of four, and more PM in mass by approximately three times. Moreover, the effects of fuel types and engine operational parameters were quantified in a systematic manner by adopting the Response Surface Method (RSM) in Design of Experiments (DoE). According to the ANOVA (Analysis of Variance), the DoE derived model was statistically significant and demonstrated that the engine load was the dominant factor for soot generation, followed by injection pressure and fuel types. Relevant combustion parameters and their link with PM emissions were further discussed, illustrating that atomization process had great impact on the ignition delay and thus affected soot generation.

N-Acetylcysteine Attenuates Cigarette Smoke-Induced Pulmonary Exacerbation in a Mouse Model of Emphysema

SESSION TITLE: COPD: Etiology SESSION TYPE: Original Investigation Poster PRESENTED ON: Saturday, April 16, 2016 at 11:45 AM - 12:45 PM PURPOSE: The purpose of this study was to investigate the effects of cigarette smoke (CS) on a mouse model of emphysema and examine the protective role of N-acetylcysteine (NAC) in the CS-induced exacerbation of pulmonary damage in the mice. METHODS: Particulate matter (PM) in cigarette smoke aerosol was analyzed by a scanning mobility particle sizer spectrometer. A mouse model of emphysema was established by injection of porcine pancreas elastase (PPE) into the trachea. Mice with emphysema were then exposed to filtered air, or cigarette smoke (CS) with intragastric administration of NAC or normal saline. Mouse body weight, survival, pulmonary tissue histology, total antioxidant capacity (T-AOC) and malonaldehyde (MDA) contents in lung tissue, and inflammatory responses were examined. RESULTS: Particles with a size ≤346 nm constituted 99.06% of CS PM. Mice exhibited ruptured alveolar septal, alveolar fusion, significantly increased mean lining interval, and reduced mean alveolar number (all P<0.05) 21 days after PPE injection. Exposure of mice with emphysema to CS exacerbated the pulmonary tissue damage, caused weight loss, significantly increased mortality, decreased T-AOC, elevated MDA contents in lung tissue, and increased interleukin (IL)-1β levels in bronchoalveolar lavage (BAL) fluids (all P<0.05). Administration of NAC attenuated those CS-induced adverse effects in the mice and increased anti-inflammatory factor IL-10 levels in BAL fluids significantly (all P<0.05). CONCLUSIONS: Exposure to CS can trigger pulmonary exacerbation in a mouse model of emphysema by reducing antioxidant capacity and increasing inflammatory responses. NAC blocks the CS-induced pulmonary injury by maintaining antioxidant capacity and reducing inflammatory responses in the mice with emphysema. CLINICAL IMPLICATIONS: These findings suggest that NAC might be a promising therapy to attenuate the exacerbation of emphysema that caused by cigarette smoke. (All the work is done at Shanghai Pulmonary Hospital) DISCLOSURE: The following authors have nothing to disclose: Liusheng Wang, Yang Hu, Yan Li, Yaru Wei, Zhaofang Yin, Yukui Du, Dong Weng, Huiping Li No Product/Research Disclosure Information

N-acetylcysteine attenuates cigaret smoke-induced pulmonary exacerbation in a mouse model of emphysema

Objective: The purpose of this study was to investigate the effects of cigaret smoke (CS) on a mouse model of emphysema and examine the protective role of N-acetylcysteine (NAC) in the CS-induced exacerbation of pulmonary damage in the mice. Method: Particulate matter (PM) in sidestream cigaret smoke aerosol was analyzed by a scanning mobility particle sizer spectrometer. A mouse model of emphysema was established by an injection of porcine pancreatic elastase (PPE) into the trachea. Mice with emphysema were then exposed to filtered air, or sidestream CS with intragastric administration of NAC or normal saline. Mouse body weight, survival, pulmonary tissue histology, total antioxidant capacity (T-AOC) and malonaldehyde (MDA) contents in lung tissue, and inflammatory responses were examined. Results: Particles with a size of ≤346 nm constituted 99.06% of CS PM. Mice exhibited ruptured alveolar septal, alveolar fusion, significantly increased mean lining interval, and reduced mean alveolar number (all p < 0.05), 21 d after PPE injection. Exposure of mice with emphysema to CS exacerbated the pulmonary tissue damage, caused weight loss, significantly increased mortality, decreased T-AOC, elevated MDA contents in lung tissue, and increased interleukin (IL)-1β levels in bronchoalveolar lavage (BAL) fluids (all p < 0.05). Administration of NAC attenuated those CS-induced adverse effects in the mice and increased anti-inflammatory factor IL-10 levels in BAL fluids significantly (all p < 0.05). Conclusions: Exposure of mice with emphysema to CS exacerbated the pulmonary damage, and NAC reduced the CS-mediated pulmonary damage by preventing oxidative damage and reducing inflammatory responses.

Emission of submicron aerosol particles in cement kilns: Total concentration and size distribution

Cement plants are responsible for particle and gaseous emissions into the atmosphere. With respect to particle emission, the greater part of is in the range from 0.05 to 5.0 µm in diameter. In the last years attention was paid to submicron particles, but there is a lack of available data on the emission from stationary sources. In this paper, concentration and size distribution of particles emitted from four cement kilns, in relationship to operational conditions (especially the use of alternative fuel to coal) of the clinker process are reported. Experimental campaigns were carried out by measuring particles concentration and size distribution at the stack of four cement plants through condensation particle counter (CPC) and scanning mobility particle sizer spectrometer (SMPS). Average total particle number concentrations were between 2000 and 4000 particles/cm3, about 8–10 times lower that those found in the corresponding surrounding areas. As for size distribution, for all the investigated plants it is stable with a unimodal distribution (120–150 nm), independent from the fuel used.Implications: The study provides information on submicron particles emitted from cement kilns in different driving conditions. In particular, the total particle number is modest and considerably lower than that measured in ambient air, whereas the particle size distribution could be influenced by the operational conditions.

Filtration of fine particles in atmospheric aerosol with electrospinning nanofibers and its size distribution

In this study, the size distribution of atmospheric aerosol in Beijing was monitored by the scanning mobility particle sizer spectrometer and the optical particle sizer. The size of particles in atmospheric aerosol was primarily distributed in the range of less than 1 μm. It showed different changes with the mass concentrations of particulate matters with an aerodynamic diameter of ⩽2.5 μm (PM2.5) for different sizes of fine particles. The amount of ultrafine particles (less than about 60 nm) decreased while the larger ones (>60 nm) increased along with the mass concentration of PM2.5 in atmospheric aerosol. This was because of the formation of the secondary atmospheric aerosol. The polylactic acid (PLA) nanofibers were prepared for filtering the aerosol by electrospinning. PLA nanofiber mats were used as the middle layer to design the composite filter membranes. Atmospheric aerosol was used as dust source in the filtration test. The results showed that the filtration efficiency of the composite filter media increased along with the thickness of nanofiber mats, which was controlled by the collection time during electrospinning. Filtration efficiency can be improved obviously by compositing with a thin layer of nanofibers.

Measurements of aerosol particles in the Škocjan Caves, Slovenia

For the first time, continuous aerosol measurements were performed in the Škocjan Caves, one of the most important cave systems in the world, and listed by UNESCO as a natural and cultural world heritage site since 1986. Measurements of PM10 were performed during three different periods: (1) in December 2011, the average background concentration was found to be about 4 μg m(-3); (2) in June 2012, a higher concentration was measured (8 μg m(-3)); and (3) from 8 to 20 August 2012, the highest concentration of 15.3 μg m(-3) was measured. Based on the PM10 measurement results, and as compared to similar measurements outside the cave, it can be hypothesized that the increase in the cave's aerosol concentration during the summer was connected to both the higher number of visitors and the polluted atmospheric air entering the cave upon entering of the cave system. Additional measurement of nanoparticles with scanning mobility particle sizer spectrometer (size between 14.1 and 710.5 nm) confirmed these findings; during the summer period, a severe raise in the total aerosol concentration of 30-50 times was found when groups of visitors entered the cave. Our results on nanoparticles demonstrated that we were able to detect very small changes and variations in aerosol concentration inside the cave. To our knowledge, these are the first results on nanoaerosol measurements in a cave, and we believe that such measurements may lead to the implementation of better protection of delicate cave systems.

The Study of HEPA/ULPA Filter Efficiency Certification with Properties of Semiconductor Materials in Semiconductor Industry

This paper aims to develop in the semiconductor plant molecular filtration efficiency with properties of semiconductor materials in the real-time. The goal of the assessment is to propose a new device based on the technologies assessed. First, the Scanning Mobility Particle Sizer Spectrometer with CPC (SMPS+C), a description of how each counter works is given. Second, a new experiment method for HEPA/ULPA filter efficiency certification in the real-time in semiconductor industry is developed. The experimental results showed that the performance of capillary had been installed and cleaned. The SMPS mean diameter fell within the range of the NIST standard. And, the HEPA/ULPA filter efficiency certification is explored. The best filtration efficiency particles size is 0.16μm. The results of this research provide the engineers with very useful information in semiconductor industry.

Ultrafine Particle Generation through Atomization Technique: The Influence of the Solution

The present work is focused on the characterization of a sub-micrometer aerosol generation system (TSI 3940) in terms of particle number distributions and total concentrations as a function of the solution. Fourteen soluble salts were tested, and different solution molar concentrations were considered. The experimental apparatus was composed of a Submicrometer Aerosol Generator TSI 3940, a Scanning Mobility Particle Sizer spectrometer (SMPS 3936, TSI), and a Condensation Particle Counter (CPC TSI 3775). Particle number distributions and total concentrations were found to change as a function of the molar concentration of the solution. In addition, at a fixed molar concentration of the solution, different particle number distributions and total concentrations were measured as a function of the salt used in the solution preparation. The mode and standard deviation of the distribution also varied as the solution changed, and thus salts able to provide number concentrations higher than the NaCl ones at low diameter ranges were obtained. For example, ammonium chloride (NH4Cl) provided particle number concentrations at 8 nm and 10 nm about 40-fold and twice the NaCl ones, respectively.