Inference of aerosol size distribution, surface area density, and volume density from multispectral extinction measurements

1997 ◽  
Author(s):  
Laurent Cazier ◽  
Colette Brogniez ◽  
Jacqueline Lenoble ◽  
Claude Devaux
Keyword(s):  
Size Distribution ◽  
Surface Area ◽  
Volume Density ◽  
Aerosol Size Distribution ◽  
Area Density

Mass or total surface area with aerosol size distribution as exposure metrics for inflammatory, cytotoxic and oxidative lung responses in rats exposed to titanium dioxide nanoparticles

2016 ◽  
Vol 33 (4) ◽  
pp. 351-364 ◽  
Author(s):  
A Noël ◽  
G Truchon ◽  
Y Cloutier ◽  
M Charbonneau ◽  
K Maghni ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Size Distribution ◽  
Surface Area ◽  
Stress Responses ◽  
Mass Concentration ◽  
Total Surface Area ◽  
Aerosol Size Distribution ◽  
Exposure Metrics ◽  
Oxidative Stress Responses ◽  
And Oxidative Stress

There is currently no consensus on the best exposure metric(s) for expressing nanoparticle (NP) dose. Although surface area has been extensively studied for inflammatory responses, it has not been as thoroughly validated for cytotoxicity or oxidative stress effects. Since inhaled NPs deposit and interact with lung cells based on agglomerate size, we hypothesize that mass concentration combined with aerosol size distribution is suitable for NP risk assessment. The objective of this study was to evaluate different exposure metrics for inhaled 5 nm titanium dioxide aerosols composed of small (SA < 100 nm) or large (LA > 100 nm) agglomerates at 2, 7, and 20 mg/m3 on rat lung inflammatory, cytotoxicity, and oxidative stress responses. We found a significant positive correlation ( r = 0.98, p < 0.01) with the inflammatory reaction, measured by the number of neutrophils and the mass concentration when considering all six (SA + LA) aerosols. This correlation was similar ( r = 0.87) for total surface area. Regarding cytotoxicity and oxidative stress responses, measured by lactate dehydrogenase and 8-isoprostane, respectively, and mass or total surface area as an exposure metric, we observed significant positive correlations only with SA aerosols for both the mass concentration and size distribution ( r > 0.91, p < 0.01), as well as for the total surface area ( r > 0.97, p < 0.01). These data show that mass or total surface area concentrations alone are insufficient to adequately predict oxidant and cytotoxic pulmonary effects. Overall, our study indicates that considering NP size distribution along with mass or total surface area concentrations contributes to a more mechanistic discrimination of pulmonary responses to NP exposure.

Microvessel surface area, density and dimensions in brain and muscle of the cephalopod Sepia officinalis

1987 ◽  
Vol 230 (1261) ◽  
pp. 459-482 ◽  
Keyword(s):  
Surface Area ◽  
Microvessel Density ◽  
Volume Fraction ◽  
Volume Density ◽  
Area Density ◽  
Neuron Cell Body ◽  
Vessel Volume ◽  
Tissue Interface ◽  
Krogh Cylinder ◽  
Good Agreement

The microvasculature of brain and muscle in the cuttlefish Sepia was studied with stereological techniques to provide information about the surface area for exchange at the blood-tissue interface which was necessary for a parallel study of the permeability of the blood-brain barrier in Sepia . Microvessel density, length, dimensions and volume fraction, and the radius of the ‘Krogh cylinder’ of tissue supplied by each microvessel were also estimated. Vertical lobe (VL) and optic lobe (OL) of brain, outer collar valve muscle (VM) and tentacle muscle (TM) were analysed in 1 μm sections of aldehyde-fixed, Epon-embedded material. ‘Microvessels’ (diameter less than 20 μm) had a surface area density S v (in the order VL, OL, VM, TM) of 134, 176, 67.9 and 13.8 cm 2 cm -3 respectively. The numbers of microvessels per unit area tissue, Q A , were 211, 395, 157 and 43 mm -2 respectively. The length density of microvessels J V = 2 x Q A . The microvessel density was significantly greater in synaptic neuropil (NP) than neuron cell body (CB) zones. Total vessel volume density V V was 3.49, 4.73, 1.88 and 0.28%, in good agreement with previous estimates using intravascular tracers. Mean microvessel diameter d̄ was in the range 4.1-6.5 μm (mode 3.9-4.9 μm). The radius of the Krogh cylinder, R, was 28, 20, 32 and 61 μm. Calculations with the Krogh-Erlang equation show that brain and valve muscle are unlikely to be hypoxic under physiological conditions, while tentacle muscle may be. The vascular parameters correlate well with the known biochemistry of cephalopod tissues. This study represents a detailed analysis of the microvasculature in a complex invertebrate and permits useful comparisons with vertebrate tissues. Values for microvascular S V , Q A , J V and d̄ in Sepia brain are similar to those of the rat, while Sepia muscle vascularity is less than in the rat.

scholarly journals Aerosol characteristics in the entrainment interface layer in relation to the marine boundary layer and free troposphere

2018 ◽  
Vol 18 (3) ◽  
pp. 1495-1506 ◽  
Author(s):  
Hossein Dadashazar ◽  
Rachel A. Braun ◽  
Ewan Crosbie ◽  
Patrick Y. Chuang ◽  
Roy K. Woods ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Size Distribution ◽  
Surface Area ◽  
Particle Number ◽  
Interface Layer ◽  
Number Concentration ◽  
Aerosol Size Distribution ◽  
Free Troposphere ◽  
Turbulent Layer ◽  
Concentration Difference

Abstract. This study uses airborne data from two field campaigns off the California coast to characterize aerosol size distribution characteristics in the entrainment interface layer (EIL), a thin and turbulent layer above marine stratocumulus cloud tops, which separates the stratocumulus-topped boundary layer (STBL) from the free troposphere (FT). The vertical bounds of the EIL are defined in this work based on considerations of buoyancy and turbulence using thermodynamic and dynamic data. Aerosol number concentrations are examined from three different probes with varying particle diameter (Dp) ranges: > 3 nm, > 10 nm, and 0.11–3.4 µm. Relative to the EIL and FT layers, the sub-cloud (SUB) layer exhibited lower aerosol number concentrations and higher surface area concentrations. High particle number concentrations between 3 and 10 nm in the EIL are indicative of enhanced nucleation, assisted by high actinic fluxes, cool and moist air, and much lower surface area concentrations than the STBL. Slopes of number concentration versus altitude in the EIL were correlated with the particle number concentration difference between the SUB and lower FT layers. The EIL aerosol size distribution was influenced by varying degrees from STBL aerosol versus subsiding FT aerosol depending on the case examined. These results emphasize the important role of the EIL in influencing nucleation and aerosol–cloud–climate interactions.

scholarly journals Aerosol Characteristics in the Entrainment Interface Layer In Relation to the Marine Boundary Layer and Free Troposphere

2017 ◽  
Author(s):  
Hossein Dadashazar ◽  
Rachel A. Braun ◽  
Ewan Crosbie ◽  
Patrick Y. Chuang ◽  
Roy K. Woods ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Size Distribution ◽  
Surface Area ◽  
Particle Number ◽  
Interface Layer ◽  
Number Concentration ◽  
Aerosol Size Distribution ◽  
Free Troposphere ◽  
Turbulent Layer ◽  
Concentration Difference

Abstract. This study uses airborne data from two field campaigns off the California coast to characterize aerosol size distribution characteristics in the entrainment interface layer (EIL), a thin and turbulent layer above marine stratocumulus cloud tops, that separates the stratocumulus-topped boundary layer (STBL) from the free troposphere (FT). The vertical bounds of the EIL are defined in this work based on considerations of buoyancy and turbulence using thermodynamic and dynamic data. Aerosol number concentrations are examined from three different probes with varying particle diameter (Dp) ranges: > 3 nm, > 10 nm, 0.11–3.4 µm. Relative to the EIL and FT layers, the sub-cloud (SUB) layer exhibited lower aerosol number concentrations and higher surface area concentrations. High particle number concentrations between 3 and 10 nm in the EIL is indicative of enhanced nucleation, assisted by high actinic fluxes, cool and moist air, and much lower surface area concentrations than the STBL. Slopes of number concentration versus altitude in the EIL were correlated with the particle number concentration difference between the SUB and lower FT layers. The EIL aerosol size distribution was influenced by varying degrees from STBL aerosol versus subsiding FT aerosol depending on the case examined. These results emphasize the important role of the EIL in influencing nucleation and aerosol-cloud-climate interactions.  

pyGAPS: A Python-Based Framework for Adsorption Isotherm Processing and Material Characterisation

2019 ◽  
Author(s):  
Paul Iacomi ◽  
Philip L. Llewellyn
Keyword(s):  
Pore Size Distribution ◽  
Pore Size ◽  
Size Distribution ◽  
Surface Area ◽  
Isosteric Heat ◽  
Material Characterisation ◽  
Mixture Adsorption ◽  
Surface Energetics ◽  
Adsorption Processing ◽  
User Friendly

Material characterisation through adsorption is a widely-used laboratory technique. The isotherms obtained through volumetric or gravimetric experiments impart insight through their features but can also be analysed to determine material characteristics such as specific surface area, pore size distribution, surface energetics, or used for predicting mixture adsorption. The pyGAPS (python General Adsorption Processing Suite) framework was developed to address the need for high-throughput processing of such adsorption data, independent of the origin, while also being capable of presenting individual results in a user-friendly manner. It contains many common characterisation methods such as: BET and Langmuir surface area, t and α plots, pore size distribution calculations (BJH, Dollimore-Heal, Horvath-Kawazoe, DFT/NLDFT kernel fitting), isosteric heat calculations, IAST calculations, isotherm modelling and more, as well as the ability to import and store data from Excel, CSV, JSON and sqlite databases. In this work, a description of the capabilities of pyGAPS is presented. The code is then be used in two case studies: a routine characterisation of a UiO-66(Zr) sample and in the processing of an adsorption dataset of a commercial carbon (Takeda 5A) for applications in gas separation.

scholarly journals Air filtration improvement of konjac glucomannan-based aerogel air filters through physical structure design

2021 ◽  
Author(s):  
Hong Qian ◽  
Ying Fang ◽  
Kao Wu ◽  
Hao Wang ◽  
Bin Li ◽  
...  
Keyword(s):  
Pore Size Distribution ◽  
Pore Size ◽  
Size Distribution ◽  
Surface Area ◽  
Physical Structure ◽  
Structure Design ◽  
Air Filtration ◽  
Air Filters ◽  
Air Filter ◽  
Purification Time

Abstract This study presents two methods to improve the air filtration performance of konjac glucomannan (KGM)-based aerogel air filters through physical structure design by changing the pore-size distribution and the surface area, using an air purifier. Results indicated that KGM-based aerogels had a comparable filtration effect with the commercial air filter with a longer purification time. This purification time could be shortened by over 50%, by changing the pore-size distribution from large size to small size or increase the surface area with the fold structure. This should boost the development of polysaccharide-based aerogel used as the air filter.

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