scholarly journals Concentrations and Size Distributions of Particle Lung-deposited Surface Area (LDSA) in an Underground Mine

2021 ◽  
Vol 21 ◽  
Author(s):  
Laura Salo ◽  
Topi Rönkkö ◽  
Sanna Saarikoski ◽  
Kimmo Teinilä ◽  
Joel Kuula ◽  
...  
Keyword(s):  
Surface Area ◽  
Underground Mine ◽  
Size Distributions ◽  
Lung Deposited Surface Area

scholarly journals Lung deposited surface area size distributions of particulate matter in different urban areas

2016 ◽  
Vol 136 ◽  
pp. 105-113 ◽  
Author(s):  
Heino Kuuluvainen ◽  
Topi Rönkkö ◽  
Anssi Järvinen ◽  
Sampo Saari ◽  
Panu Karjalainen ◽  
...  
Keyword(s):  
Particulate Matter ◽  
Surface Area ◽  
Urban Areas ◽  
Size Distributions ◽  
Lung Deposited Surface Area

Abrasive Effects in Oxide Chemical Mechanical Polishing

1999 ◽  
Vol 566 ◽  
Author(s):  
Uday Mahajan ◽  
Marc Bielmann ◽  
Rajiv K. Singh
Keyword(s):  
Particle Size ◽  
Surface Morphology ◽  
Surface Area ◽  
Chemical Mechanical Polishing ◽  
Material Removal ◽  
Sol Gel ◽  
Mechanical Polishing ◽  
Size Distributions ◽  
Abrasive Properties

In this study, we have characterized the effects of abrasive properties, primarily particle size, on the Chemical Mechanical Polishing (CMP) of oxide films. Sol-gel silica particles with very narrow size distributions were used for preparing the polishing slurries. The results indicate that as particle size increases, there is a transition in the mechanism of material removal from a surface area based mechanism to an indentation-based mechanism. In addition, the surface morphology of the polished samples was characterized, with the results showing that particles larger than 0.5 μm are detrimental to the quality of the SiO2 surface.

scholarly journals Optimal estimation retrieval of aerosol microphysical properties from SAGE~II satellite observations in the volcanically unperturbed lower stratosphere

2010 ◽  
Vol 10 (9) ◽  
pp. 4295-4317 ◽  
Author(s):  
D. Wurl ◽  
R. G. Grainger ◽  
A. J. McDonald ◽  
T. Deshler
Keyword(s):  
Surface Area ◽  
Lower Stratosphere ◽  
Optimal Estimation ◽  
Retrieval Algorithm ◽  
Aerosol Extinction ◽  
Size Distributions ◽  
Extinction Data ◽  
Aerosol Properties ◽  
Area And Volume

Abstract. Stratospheric aerosol particles under non-volcanic conditions are typically smaller than 0.1 μm. Due to fundamental limitations of the scattering theory in the Rayleigh limit, these tiny particles are hard to measure by satellite instruments. As a consequence, current estimates of global aerosol properties retrieved from spectral aerosol extinction measurements tend to be strongly biased. Aerosol surface area densities, for instance, are observed to be about 40% smaller than those derived from correlative in situ measurements (Deshler et al., 2003). An accurate knowledge of the global distribution of aerosol properties is, however, essential to better understand and quantify the role they play in atmospheric chemistry, dynamics, radiation and climate. To address this need a new retrieval algorithm was developed, which employs a nonlinear Optimal Estimation (OE) method to iteratively solve for the monomodal size distribution parameters which are statistically most consistent with both the satellite-measured multi-wavelength aerosol extinction data and a priori information. By thus combining spectral extinction measurements (at visible to near infrared wavelengths) with prior knowledge of aerosol properties at background level, even the smallest particles are taken into account which are practically invisible to optical remote sensing instruments. The performance of the OE retrieval algorithm was assessed based on synthetic spectral extinction data generated from both monomodal and small-mode-dominant bimodal sulphuric acid aerosol size distributions. For monomodal background aerosol, the new algorithm was shown to fairly accurately retrieve the particle sizes and associated integrated properties (surface area and volume densities), even in the presence of large extinction uncertainty. The associated retrieved uncertainties are a good estimate of the true errors. In the case of bimodal background aerosol, where the retrieved (monomodal) size distributions naturally differ from the correct bimodal values, the associated surface area (A) and volume densities (V) are, nevertheless, fairly accurately retrieved, except at values larger than 1.0 μm2 cm−3 (A) and 0.05 μm3 cm−3 (V), where they tend to underestimate the true bimodal values. Due to the limited information content in the SAGE II spectral extinction measurements this kind of forward model error cannot be avoided here. Nevertheless, the retrieved uncertainties are a good estimate of the true errors in the retrieved integrated properties, except where the surface area density exceeds the 1.0 μm2 cm−3 threshold. When applied to near-global SAGE II satellite extinction measured in 1999 the retrieved OE surface area and volume densities are observed to be larger by, respectively, 20–50% and 10–40% compared to those estimates obtained by the SAGE~II operational retrieval algorithm. An examination of the OE algorithm biases with in situ data indicates that the new OE aerosol property estimates tend to be more realistic than previous estimates obtained from remotely sensed data through other retrieval techniques. Based on the results of this study we therefore suggest that the new Optimal Estimation retrieval algorithm is able to contribute to an advancement in aerosol research by considerably improving current estimates of aerosol properties in the lower stratosphere under low aerosol loading conditions.

Surface area and size distributions of soil particles

1993 ◽  
Vol 73 ◽  
pp. 65-76 ◽  
Author(s):  
M. Borkovec ◽  
Q. Wu ◽  
G. Degovics ◽  
P. Laggner ◽  
H. Sticher
Keyword(s):  
Surface Area ◽  
Size Distributions ◽  
Soil Particles

scholarly journals Comparison of Nitrogen Adsorption and Mercury Penetration Results. Pore Size Distributions for a Series of Mo-A12O3 Catalysis with Increasing MoO3 Content

1987 ◽  
Vol 4 (1-2) ◽  
pp. 87-104 ◽  
Author(s):  
Bruce D Adkins ◽  
Jill B. Heink ◽  
Burtron H. Davis
Keyword(s):  
Pore Size ◽  
Surface Area ◽  
Three Dimensional ◽  
Nitrogen Adsorption ◽  
Bet Surface Area ◽  
Size Distributions ◽  
Electron Microscopic ◽  
Pore Size Distributions ◽  
Electron Microscopic Data ◽  
Penetration Data

Scanning electron microscopic data, X-ray diffraction patterns and porosity measurements are consistent with a structure for an Mo-A12O3 catalyst series containing a single surface layer of Mo up to the point where the Mo loadings exceed the amount required for a monolayer. For greater Mo loadings than required for a monolayer, three dimensional orthorhombic MoO3 is also present. The cumulative pore volume, on an alumina basis, does not appear to be significantly altered by MoO3 loadings up to about 15 wt.%. The BET surface area, on an alumina basis, remains constant with Mo loading. However, the apparent surface area calculated from mercury penetration data decreases with Mo loading. For these materials with cylindrical pores, the Broekhoff-deBoer model for the calculation of pore size distributions produced closer agreement to the mercury penetration pore size distribution. This is in contrast to materials composed of nonporous spheres where the Broekhoff-deBoer model provided poorer agreement to mercury penetration results than either the Cohan or a packed sphere model. The results show that, within a factor of two the pore size distributions calculated from nitrogen adsorption and mercury penetration data are comparable.

Ni and Cu Incorporated Mesoporous Nanocomposite Catalytic Materials

2008 ◽  
Vol 8 (2) ◽  
pp. 549-556 ◽  
Author(s):  
Asli Nalbant ◽  
Timur Dogu ◽  
Suna Balci
Keyword(s):  
Pore Size ◽  
Surface Area ◽  
Atomic Ratio ◽  
Nanocomposite Materials ◽  
Size Distributions ◽  
Hydrothermal Route ◽  
Average Pore ◽  
Pore Size Distributions ◽  
Xrd Patterns ◽  
Mcm 41

Nickel and copper incorporated MCM-41-like mesoporous nanocomposite materials prepared by the direct hydrothermal synthesis and the impregnation procedures showed highly attractive pore structure and surface area results for catalytic applications. The XRD patterns showed that characteristic MCM-41 structure was preserved for the materials synthesized following an impregnation procedure before the calcination step. The surface area of the Cu impregnated material with a quite high Cu/Si atomic ratio (0.19) was 631 m2/g. Very narrow pore size distributions with an average pore diameter of about 2.7 nm were obtained as a result of plugging of some of the smaller pores by Cu nanoballs. For lower metal to Si ratios (for instance for Ni/Si = 0.06) much higher surface area values (1130 m2/g) were obtained. In the case of nanocomposite materials synthesized by the direct hydrothermal route, MCM-41 structure was not destroyed for samples containing metal to Si atomic ratios as high as 0.12. In the case of materials containing Cu/Si and Ni/Si ratios over 0.2 wider pore size distributions and some decrease of surface area were observed.

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