scholarly journals Ultrafine Particle and Fiber Production in Micro-Gravity

1986 ◽  
Vol 87 ◽  
Author(s):  
George W. Webb
Keyword(s):  
Experimental Test ◽  
Ultrafine Particles ◽  
Ultrafine Particle ◽  
Inert Gas ◽  
Reduced Gravity ◽  
Fiber Production ◽  
Evaporation And Condensation ◽  
Gravity Driven ◽  
Micro Gravity

AbstractWe have investigated the technique of evaporation and condensation of material in an inert gas (ECIIG) for the purpose of preparing ultrafine particles (of order 10 nm in diameter) with a narrow distribution of sizes. Gravity driven convection increases the rate of coalescence of the particles leading to larger sizes and a broader distribution. Here we report on analysis and experiments to investigate coalescence of particles. The possibility of reducing coalescence in micro-gravity is discussed. An experimental test in reduced gravity to be performed in a KC135 aircraft is described briefly.

scholarly journals Impact on Ultrafine Particles Concentration and Turbulent Fluxes of SARS-CoV-2 Lockdown in a Suburban Area in Italy

Atmosphere ◽  
2021 ◽  
Vol 12 (3) ◽  
pp. 407
Author(s):  
Antonio Donateo ◽  
Adelaide Dinoi ◽  
Gianluca Pappaccogli
Keyword(s):  
Ultrafine Particles ◽  
Particle Number ◽  
Ultrafine Particle ◽  
Turbulent Fluxes ◽  
Number Concentration ◽  
Suburban Area ◽  
Observation Site ◽  
Meteorological Forcing ◽  
Restrictive Measures ◽  
Measurement Area

In order to slow the spread of SARS-CoV-2, governments have implemented several restrictive measures (lockdown, stay-in-place, and quarantine policies). These provisions have drastically changed the routines of residents, altering environmental conditions in the affected areas. In this context, our work analyzes the effects of the reduced emissions during the COVID-19 period on the ultrafine particles number concentration and their turbulent fluxes in a suburban area. COVID-19 restrictions did not significantly reduce anthropogenic related PM10 and PM2.5 levels, with an equal decrement of about 14%. The ultrafine particle number concentration during the lockdown period decreased by 64% in our measurement area, essentially due to the lower traffic activity. The effect of the restriction measures and the reduction of vehicles traffic was predominant in reducing concentration rather than meteorological forcing. During the lockdown in 2020, a decrease of 61% in ultrafine particle positive fluxes can be observed. At the same time, negative fluxes decreased by 59% and our observation site behaved, essentially, as a sink of ultrafine particles. Due to this behavior, we can conclude that the principal particle sources during the lockdown were far away from the measurement site.

scholarly journals Simultaneous coastal measurements of ozone deposition fluxes and iodine-mediated particle emission fluxes with subsequent CCN formation

2009 ◽  
Vol 9 (5) ◽  
pp. 20567-20597 ◽  
Author(s):  
J. D. Whitehead ◽  
G. McFiggans ◽  
M. W. Gallagher ◽  
M. J. Flynn
Keyword(s):  
Ultrafine Particles ◽  
Littoral Zone ◽  
Ultrafine Particle ◽  
High Tide ◽  
Particle Growth ◽  
Particle Emission ◽  
Deposition Fluxes ◽  
Ozone Deposition ◽  
Significant Difference ◽  
Emission Fluxes

Abstract. Here we present the first observations of simultaneous ozone deposition fluxes and ultrafine particle emission fluxes over an extensive infra-littoral zone. Fluxes were measured by the eddy covariance technique at the Station Biologique de Roscoff, on the coast of Brittany, north-west France. This site overlooks a very wide (3 km) littoral zone controlled by very deep tides (9.6 m) exposing extensive macroalgae beds available for significant iodine mediated photochemical production of ultrafine particles. The aspect at the Station Biologique de Roscoff provides an extensive and relatively flat, uniform fetch within which micrometeorological techniques may be utilized to study links between ozone deposition to macroalgae (and sea water) and ultrafine particle production. Ozone deposition to seawater at high tide was significantly slower (vd[O3]=0.302±0.095 mm s−1) than low tidal deposition. A statistically significant difference in the deposition velocities to macroalgae at low tide was observed between night time (vd[O3]=1.00±0.10 mm s−1) and daytime (vd[O3]=2.05±0.16s−1) when ultrafine particle formation results in apparent particle emission. Very high emission fluxes of ultrafine particles were observed during daytime periods at low tides ranging from 50 000 particles cm−2 s−1 to greater than 200 000 particles cm−2 s−1 during some of the lowest tides. These emission fluxes exhibited a significant relationship with particle number concentrations comparable with previous observations at another location. Apparent particle growth rates were estimated to be in the range 17–150 nm h−1 for particles in the size range 3–10 nm. Under certain conditions, particle growth may be inferred to continue to greater than 120 nm over tens of hours; sizes at which they may readily behave as cloud condensation nuclei (CCN) under reasonable supersaturations that may be expected to pertain at the top of the marine boundary layer. These results link direct depositional loss and photochemical destruction of ozone to the formation of particles and hence CCN from macroalgal emissions at a coastal location.

scholarly journals Laboratory and field evaluation of the Aerosol Dynamics Inc. concentrator (ADIc) for aerosol mass spectrometry

2019 ◽  
Author(s):  
Sanna Saarikoski ◽  
Leah R. Williams ◽  
Steven R. Spielman ◽  
Gregory S. Lewis ◽  
Arantzazu Eiguren-Fernandez ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Concentration Factor ◽  
Ultrafine Particles ◽  
Ultrafine Particle ◽  
Chemical Characterization ◽  
Field Evaluation ◽  
Aerosol Dynamics ◽  
Aerosol Mass ◽  
Aerosol Mass Spectrometry ◽  
Road Paving

Abstract. An air-to-air ultrafine particle concentrator (Aerosol Dynamics Inc. concentrator; ADIc) has been designed to enhance on-line chemical characterization of ambient aerosols by aerosol mass spectrometry. The ADIc employs a three-stage, moderated water-based condensation growth tube coupled to an aerodynamic focusing nozzle to concentrate ultrafine particles into a portion of the flow. The system can be configured to sample between 1.0–1.7 L min−1 with an output concentrated flow between 0.08–0.12 L min−1, resulting in a theoretical concentration factor (sample flow/output flow) ranging from 8 to 21. Laboratory tests with monodisperse particles show that the ADIc is effective for particles as small as 10 nm. Laboratory experiments conducted with the Aerosol Mass Spectrometer (AMS) showed no shift in the particle size after the ADIc, as measured by the AMS particle time-of-flight. The ADIc-AMS system was operated unattended over a one-month period near Boston, Massachusetts. Comparison to a parallel AMS without the concentrator showed concentration factors of 9.7 ± 0.15 and 9.1 ± 0.1 for sulfate and nitrate, respectively, when operated with a theoretical concentration factor of 10.5 ± 0.3. Concentration factor of organics was lower, possibly due to the presence of large particles from nearby road-paving operations, and a difference in aerodynamic lens cutoff between the two AMS instruments. Another field deployment was carried out in Helsinki, Finland. Two ~ 10-day measurement periods showed good correlation for the concentrations of organics, sulfate, nitrate and ammonium measured with an Aerosol Chemical Speciation Monitor (ACSM) after the ADIc, and a parallel AMS without the concentrator. Additional experiments with an AMS alternating between the ADIc and a bypass line demonstrated that the concentrator did not change the size distribution or the chemistry of the ambient aerosol particles.

scholarly journals An embryonic zebrafish model to screen disruption of gut-vascular-barriers upon exposure to ambient ultrafine particles

2020 ◽  
Author(s):  
Kyung In Baek ◽  
Yi Qian ◽  
Chih-Chiang Chang ◽  
Ryan O’Donnell ◽  
Ehsan Soleimanian ◽  
...  
Keyword(s):  
Ultrafine Particles ◽  
Ultrafine Particle ◽  
Intestinal Barrier ◽  
Epidemiological Studies ◽  
Ambient Particulate Matter ◽  
Zebrafish Model ◽  
Redox Active ◽  
Capillary Plexus ◽  
Polycyclic Aromatic ◽  
Notch Activation

AbstractEpidemiological studies have linked exposure to ambient particulate matter (PM) with gastrointestinal (GI) diseases. Ambient ultrafine particle (UFP) are the redox-active sub-fraction of PM2.5, harboring elemental and polycyclic aromatic hydrocarbons from urban environmental sources including diesel and gasoline exhausts. The gut vascular barrier (GVB) regulates paracellular trafficking and systemic disseminations of ingested microbes and toxins. Here, we posit that acute UFP ingestion disrupts the integrity of the intestinal barrier by modulating intestinal Notch activation. Using zebrafish embryos, we performed micro-gavage with the FITC-conjugated dextran (FD10, 10 kDa) to assess the disruption of GVB integrity upon UFP exposure. Following micro-gavage, FD10 retained in the embryonic GI system, migrated through the cloaca. Conversely, co-gavaging UFP increased transmigration of FD10 across the intestinal barrier, and FD10 fluorescence occurred in the venous capillary plexus. Ingestion of UFP further impaired the mid-intestine morphology. We performed micro-angiogram of FD10 to corroborate acute UFP-mediated disruption of GVB. Transient genetic and pharmacologic manipulations of global Notch activity suggested Notch regulation of the GVB. Overall, our integration of a genetically tractable embryonic zebrafish and micro-gavage technique provided epigenetic insights underlying ambient UFP ingestion disrupts the GVB.Graphic Abstract

scholarly journals Summertime observations of elevated levels of ultrafine particles in the high Arctic marine boundary layer

2017 ◽  
Vol 17 (8) ◽  
pp. 5515-5535 ◽  
Author(s):  
Julia Burkart ◽  
Megan D. Willis ◽  
Heiko Bozem ◽  
Jennie L. Thomas ◽  
Kathy Law ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Ultrafine Particles ◽  
Marine Boundary Layer ◽  
Ultrafine Particle ◽  
High Arctic ◽  
Particle Formation ◽  
Open Ocean ◽  
Biologically Active ◽  
The Arctic ◽  
Depositional Processes

Abstract. Motivated by increasing levels of open ocean in the Arctic summer and the lack of prior altitude-resolved studies, extensive aerosol measurements were made during 11 flights of the NETCARE July 2014 airborne campaign from Resolute Bay, Nunavut. Flights included vertical profiles (60 to 3000 m above ground level) over open ocean, fast ice, and boundary layer clouds and fogs. A general conclusion, from observations of particle numbers between 5 and 20 nm in diameter (N5 − 20), is that ultrafine particle formation occurs readily in the Canadian high Arctic marine boundary layer, especially just above ocean and clouds, reaching values of a few thousand particles cm−3. By contrast, ultrafine particle concentrations are much lower in the free troposphere. Elevated levels of larger particles (for example, from 20 to 40 nm in size, N20 − 40) are sometimes associated with high N5 − 20, especially over low clouds, suggestive of aerosol growth. The number densities of particles greater than 40 nm in diameter (N >  40) are relatively depleted at the lowest altitudes, indicative of depositional processes that will lower the condensation sink and promote new particle formation. The number of cloud condensation nuclei (CCN; measured at 0.6 % supersaturation) are positively correlated with the numbers of small particles (down to roughly 30 nm), indicating that some fraction of these newly formed particles are capable of being involved in cloud activation. Given that the summertime marine Arctic is a biologically active region, it is important to better establish the links between emissions from the ocean and the formation and growth of ultrafine particles within this rapidly changing environment.

scholarly journals Sources and Eco-toxicological Effects of Ultrafine Particle Matters

2019 ◽  
Vol 136 ◽  
pp. 06008
Author(s):  
SHAN Huimei ◽  
LUO Linbo ◽  
WANG Shaopei ◽  
LIAO Danxue ◽  
ZHAO Chaoran ◽  
...  
Keyword(s):  
Pollution Control ◽  
Air Pollutants ◽  
Ultrafine Particles ◽  
Ultrafine Particle ◽  
Ambient Air ◽  
Toxicological Effects ◽  
Atmospheric Particulates ◽  
Environmental Air ◽  
Main Components ◽  
Environmental Air Pollution

Environmental air pollution has become an important threat to human health. As one of the major air pollutants, atmospheric particulates have received attention widely. In which, ultrafine particulate matters (UPM) with diameter below 0.1μm have become the main components of ambient air particulates, posing a serious threat to the health of the organism. Therefore, this paper investigated and summarized the research on ultrafine particles at home and abroad, systematically analysed the sources of UPM in ambient air, investigated its toxicological effects of ultrafine particles on the respiratory system, cardiovascular system, and central nervous system of organisms. This study will provide a theoretical reference for environmental air protection and pollution control in China.

Growth of Ultrafine Particles Through a Minichannel With Capillary Structure

2009 ◽  
Author(s):  
Jin Young Choi ◽  
Sang Young Son
Keyword(s):  
Ultrafine Particles ◽  
Detection System ◽  
Laser Sheet ◽  
Aerosol Particles ◽  
Ultrafine Particle ◽  
Counting Efficiency ◽  
Main Body ◽  
Capillary Structure ◽  
Standard Size ◽  
Condensational Growth

The development of personal monitoring devices with the size of a human palm so that people can carry or wear with them has been of importance over a decade. Many small apparatuses to be able to detect the chemical and biological agent have been developed and commercialized, but the portable and wearable device to detect small particles, especially with the size of nanometer has not been developed yet up to our knowledge. In the present work, a new miniature device which is small enough for the application to a personal ultrafine particle monitoring sensor is described. The enlargement of particle size through heterogeneous condensational growth is used for the whole system. And, for miniaturization, microscale multiphase fluid control and microstructured surface modification technologies are employed. In order to evaluate the performance of the developed device, the condensational growth of ultrafine aerosol particles in a minichannel made of capillary structure was investigated through a laser sheet visualization technique. The main body of the device was constructed by cutting a commercially produced capillary structure. The physical dimension of the developed device is less than 1/10 of the smallest design commercially available. The polydisperse aerosol particles with the mean diameter of 20nm and concentration of more than 60,000 particles/cc and purified water as condensing fluid were used for test. The image of condensed droplets grown by the device was compared with those of standard size PSL particles. The experimental results show that the entered ultrafine particles successfully grew to micron size droplets through the developed condensation chamber and then could be counted with the optical detection system. Furthermore, the counting efficiency and the change of average size of condensed droplets were also investigated with the operating condition.

Two-Way Coupling Model for Fractal-Like Agglomerate-Laden Multiphase Flow

2009 ◽  
Author(s):  
Mingzhou Yu ◽  
Jianzhong Lin ◽  
Kai Zhang ◽  
Gaohui Zhang
Keyword(s):  
Ultrafine Particles ◽  
Particle System ◽  
Fractal Theory ◽  
Ultrafine Particle ◽  
Coupling Model ◽  
Industrial Applications ◽  
Particle Coagulation ◽  
Governing Equations ◽  
Dilute Gas ◽  
General Dynamic

The disturbing of ultrafine particles on carrying phase is usually ignored in studies on dilute ultrafine particle systems. In a dense fractal-like agglomerate system, however, the effect of particle phase on carrier phase should be considered due to its unique heat and mass transfer while the corresponding mathematical model for this problem has not been established. By taking the agglomerate-laden suspension as a single pseudo fluid, we propose a two-way coupling model in which the developed governing equations for suspension and particle general dynamic equation (PGDE) for particle coagulation and breakage due to turbulence are simultaneously solved. The Taylor-expansion moment method has been applied to solve fractal-like aggregate process and dilute gas-to-particle conversion, and in this study it is further extended to close the PGDE equation by invoking fractal theory. The newly coupling model is not limited in dilute particle system, and thus it is expected to play important roles in studying dense fractal-like agglomerate synthesis or other particulate industrial applications.

scholarly journals Cigarette-related cadmium and environmental pollution exposure are reflected in airway ultrafine particle content

2020 ◽  
Vol 6 (3) ◽  
pp. 00361-2019
Author(s):  
Einat Klein Fireman ◽  
Yochai Adir ◽  
Elizabeth Fireman ◽  
Aharon Kessel
Keyword(s):  
Environmental Pollution ◽  
Ultrafine Particles ◽  
Exhaled Breath Condensate ◽  
Ultrafine Particle ◽  
Exhaled Breath ◽  
Cadmium Content ◽  
Inflammatory Status ◽  
Copd Patients ◽  
High Level

IntroductionParticulate matter (PM) and cigarette-related cadmium exposure increases inflammation and smokers' susceptibility to developing lung diseases. The majority of inhaled metals are attached to the surface of ultrafine particles (UFPs). A low inhaled UFP content in exhaled breath condensate (EBC) reflects a high inflammatory status of airways.MethodsEBC was collected from 58 COPD patients and 40 healthy smokers and nonsmokers. Participants underwent spirometry, diffusion capacity, EBC and blood sampling. Environmental pollution data were collected from monitoring stations. UFPs were measured in EBC and serum, and cadmium content was quantified.ResultsSubjects with low UFP concentrations in EBC (<0.18×108·mL−1) had been exposed to higher long-term PM2.5 levels versus subjects with high UFP concentrations in EBC (>0.18×108·mL−1) (21.9 µg·m−3versus 17.4 µg·m−3, p≤0.001). Long-term PM2.5 exposure levels correlated negatively with UFP concentrations in EBC and positively with UFP concentrations in serum (r=−0.54, p≤0.001 and r=0.23, p=0.04, respectively). Healthy smokers had higher cadmium levels in EBC versus healthy nonsmokers and COPD patients (25.2 ppm versus 23.7 ppm and 23.3 ppm, p=0.02 and p=0.002, respectively). Subjects with low UFP concentrations in EBC also had low cadmium levels in EBC versus subjects with high UFP levels (22.8 ppm versus 24.2 ppm, p=0.004)ConclusionsLow UFP concentration in EBC is an indicator of high-level PM exposure. High cadmium levels in EBC among smokers and the association between cadmium and UFP content in EBC among COPD patients indicate cadmium lung toxicity.

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