Influence of Mineral Dust Surface Characteristics and Generation of Reactive Species

2004 ◽  
pp. 139-160 ◽  
Author(s):  
David Kamp
Keyword(s):  
Mineral Dust ◽  
Surface Characteristics ◽  
Reactive Species ◽  
Dust Surface

scholarly journals Kinetics and mechanism of the uptake of N<sub>2</sub>O<sub>5</sub> on mineral dust at 298 K

2005 ◽  
Vol 5 (4) ◽  
pp. 5645-5667
Author(s):  
S. Seisel ◽  
C. Börensen ◽  
R. Vogt ◽  
R. Zellner
Keyword(s):  
Steady State ◽  
Mineral Dust ◽  
Heterogeneous Reaction ◽  
Kinetics And Mechanism ◽  
Saharan Dust ◽  
Uptake Coefficient ◽  
Uptake Rates ◽  
Hydrolysis Of ◽  
Dust Surface ◽  
Initial Uptake

Abstract. The heterogeneous reaction of N2O5 with mineral (Saharan) dust has been studied at T=298 K using a combination of Knudsen and DRIFTS cell for kinetic and product investigations, respectively. The initial uptake coefficient has been determined to be γ=(8.0±0.3)·10−2. This uptake slowly saturates into a steady state uptake of γ=(1.3±0.3)10−2 suggesting that reaction of N2O5 with the mineral dust surface and hydrolysis of N2O5 on the surface take place simultaneously. Moreover, the product investigations suggest that N2O5 is irreversibly taken up forming nitrate on the surface. The uptake rates of N2O5 on Saharan dust are large enough to influence the photo-oxidant budget of the atmosphere.

scholarly journals Kinetics and mechanism of the uptake of N<sub>2</sub>O<sub>5</sub> on mineral dust at 298 K

2005 ◽  
Vol 5 (12) ◽  
pp. 3423-3432 ◽  
Author(s):  
S. Seisel ◽  
C. Börensen ◽  
R. Vogt ◽  
R. Zellner
Keyword(s):  
Mineral Dust ◽  
Heterogeneous Reaction ◽  
Recent Model ◽  
Saharan Dust ◽  
Uptake Coefficient ◽  
Model Calculations ◽  
Upper Limits ◽  
Uptake Rates ◽  
Hydrolysis Of ◽  
Dust Surface

Abstract. The heterogeneous reaction of N2O5 with mineral (Saharan) dust has been studied at T=298 K using a combination of Knudsen and DRIFTS cells for kinetic and product investigations, respectively. The initial uptake coefficient has been determined to be γ=(8.0±0.3)·10−2. This uptake slowly saturates into a steady state uptake of γ=(1.3±0.3)·10−2 suggesting that reaction of N2O5 with the mineral dust surface and hydrolysis of N2O5 on the surface take place simultaneously. Both uptake coefficients have been calculated on the basis of the geometric (projected) surface area of the sample and must therefore be regarded as upper limits. In addition, the product investigations show that N2O5 is irreversibly taken up to form nitrate on the surface. Recent model calculations suggest that the uptake rates of N2O5 on Saharan dust which we measured may be large enough to influence the photo-oxidant budget of the atmosphere.

Photochemistry of mineral dust surface as a potential atmospheric renoxification process

2009 ◽  
Vol 36 (5) ◽  
Author(s):  
Marieme Ndour ◽  
Pierre Conchon ◽  
Barbara D'Anna ◽  
Oumar Ka ◽  
Christian George
Keyword(s):  
Mineral Dust ◽  
Dust Surface

scholarly journals Modelling mineral dust in the Central Asian region

2019 ◽  
Vol 99 ◽  
pp. 02012
Author(s):  
Bernd Heinold ◽  
Ina Tegen
Keyword(s):  
Central Asia ◽  
Climate Model ◽  
Mineral Dust ◽  
Land Use Changes ◽  
Surface Characteristics ◽  
Maximum Activity ◽  
Transport Pathways ◽  
Mountain Glaciers ◽  
Central Asian ◽  
Local Dust

In Central Asia, climate and air quality are largely affected by local and long-travelled mineral dust. For the last century, the area has experienced severe land-use changes and water exploitation producing new dust sources. Today global warming causes rapid shrinking of mountain glaciers with yet unknow consequences for dust and its climate effects. Despite the importance for a growing population, only little is known about sources, transport pathways and properties of Central Asian dust. A transport study with a global aerosol-climate model is undertaken to investigate the life cycle of mineral dust in Central Asia for the period of a remote-sensing campaign in Tajikistan in 2015–2016. An initial evaluation with sun photometer measurements shows reasonable agreement for the average amount of dust, but a significant weakness of the model in reproducing the seasonality of local dust with maximum activity in summer. Source apportionment reveals a major contribution from Arabia throughout the year in accordance with observations. In the model, local sources mainly contribute in spring and autumn while summer-time dust production is underestimated. The results underline the importance of considering long-range transport and, locally, a detailed representation of atmospheric dynamics and surface characteristics for modelling dust in Central Asia.

Medial Smooth Muscle Cell Proliferation in the Balloon Injured Rabbit Aorta: Effect of a Thiazole Compound with Platelet Inhibitory Activity

1984 ◽  
Vol 51 (01) ◽  
pp. 075-078 ◽  
Author(s):  
R G Schaub ◽  
C A Simmons
Keyword(s):  
Smooth Muscle ◽  
Platelet Aggregation ◽  
Balloon Catheter ◽  
Rabbit Aorta ◽  
Surface Characteristics ◽  
Inhibitory Effect ◽  
Lesion Size ◽  
Blue Staining ◽  
Morphologic Characteristics ◽  
Time Period

SummaryTwenty-seven adult male New Zealand rabbits (3–4 kgs) were used in this study. Six rabbits received vehicle, 3 groups of 6 each received doses of 4,5-bis(p-methoxyphenyl)-2-(trifluoromethyl)- thiazole, (U-53,059), at 0.3 mg/kg, 3.0 mg/kg and 30.0 mg/kg/day respectively. Drug and vehicle doses were given orally each day starting 3 days before balloon injury and continuing for the entire 2 week time period. Three rabbits were used as nontreated sham controls. In the vehicle and U-53,059 treated groups aortae were denuded of endothelial cells by balloon catheter injury. Two weeks after injury platelet aggregation to collagen was measured and the aortae removed for analysis of surface characteristics by scanning electron microscopy and lesion size by morphometry. All doses of U-53,059 inhibited platelet aggregation. The 3.0 and 30.0 mg/kg groups had the greatest inhibitory effect. All balloon injured aortae had the same morphologic characteristics. All vessels had similar extent and intensity of Evan’s blue staining, similar areas of leukocyte/platelet adhesion, and a myointimal cell cover of transformed smooth muscle cells. The myointimal proliferative response was not inhibited at any of the drug doses studied.

Photocatalytic activity of TiO2 synthesized by anodization and anodic spark deposition

MRS Advances ◽  
2020 ◽  
Vol 5 (61) ◽  
pp. 3141-3152
Author(s):  
Alma C. Chávez-Mejía ◽  
Génesis Villegas-Suárez ◽  
Paloma I. Zaragoza-Sánchez ◽  
Rafael Magaña-López ◽  
Julio C. Morales-Mejía ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Photocatalytic Activity ◽  
Surface Characteristics ◽  
Amorphous Solids ◽  
X Ray Diffraction ◽  
X Ray ◽  
Catalytic Activities ◽  
Anodic Spark Oxidation ◽  
Porous Surfaces ◽  
Scanning Electron

AbstractSeveral photocatalysts, based on titanium dioxide, were synthesized by spark anodization techniques and anodic spark oxidation. Photocatalytic activity was determined by methylene blue oxidation and the catalytic activities of the catalysts were evaluated after 70 hours of reaction. Scanning Electron Microscopy and X Ray Diffraction analysis were used to characterize the catalysts. The photocatalyst prepared with a solution of sulfuric acid and 100 V presented the best performance in terms of oxidation of the dye (62%). The electric potential during the synthesis (10 V, low potential; 100 V, high potential) affected the surface characteristics: under low potential, catalyst presented smooth and homogeneous surfaces with spots (high TiO2 concentration) of amorphous solids; under low potential, catalyst presented porous surfaces with crystalline solids homogeneously distributed.

Soft Tissue Responses and Attachment to Porous Titanium with Different Surface Characteristics

2006 ◽  
Vol 9 (2) ◽  
pp. 127-134
Author(s):  
Yao Wu ◽  
Hu Li ◽  
Tun Yuan ◽  
Chunlin Deng ◽  
Bangcheng Yang ◽  
...  
Keyword(s):  
Soft Tissue ◽  
Surface Characteristics ◽  
Porous Titanium ◽  
Tissue Responses
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