A laboratory-scale membrane filtration cell was constructed to enable direct microscopic observation of microbial cell deposition and release in cross-flow microfiltration. Initial deposition rates determined from microscopic images were interpreted through an interaction force model. Experimentally derived deposition rates and model calculations confirmed that initial cell and particle deposit...

Particle deposition and suspension in a horizontal pipe flow have been studied. A 3D numerical multiphase mixture model available in Fluent 6.0 is used. The model solves continuity and momentum equations for the mixture and volume fraction equations for the secondary phases. Transport equations were also solved for turbulence parameters of the particulate phases. Gravitational and hydrodynamic ...

Nonmethane hydrocarbons (NMHCs) play an important role in the atmosphere. Photochemical oxidation of hydrocarbons leads to ozone (O3), organic acid, and carbon dioxide (CO2) production, with major implications for local and regional air quality, acid deposition, and the greenhouse effect. In addition, emissions of atmospheric NMHCs lead to an increased aerosol loading, which has major implicati...

[1] We investigate the solar cycle modulation of the quasi-biennial oscillation (QBO) in stratospheric zonal winds and its impact on stratospheric ozone with an updated version of the zonally averaged CHEM2D middle atmosphere model. We find that the duration of the westerly QBO phase at solar maximum is 3 months shorter than at solar minimum, a more robust result than in an earlier CHEM2D study...

Eight distinct hydroxy nitrates are stable products of the first step in the atmospheric oxidation of isoprene by OH. The subsequent chemical fate of these molecules affects global and regional production of ozone and aerosol as well as the location of nitrogen deposition. We synthesized and purified 3 of the 8 isoprene hydroxy nitrate isomers: (E/Z)-2-methyl-4-nitrooxybut-2-ene-1-ol and 3-meth...

Tenascin-C is an extracellular matrix component which is transiently expressed in association with epithelial cell detachment, proliferation, and migration. This molecule has been identified in respiratory tissue, but little is known about the cellular source of tenascin-C or the factors that regulate its production. Since air pollutants are known to disrupt epithelial integrity, we investigate...

Atmospheric nitrogen (N) dry deposition is an important component in total N deposition. However, uncertainty exists in the assessment of global dry deposition. Here, we develop empirical models for estimating ground N concentrations using NO2 satellite measurements from the Ozone Monitoring Instrument (OMI) and ground measurements from 555 monitoring sites. Global patterns and trends in the fl...

To gain insight into the limitations imposed by a typical Mediterranean-climate summer drought on the uptake of carbon and ozone in the ponderosa pine (Pinus ponderosa Dougl. ex Laws.) ecosystem, we compared diurnal trends in leaf physiology of young trees in a watered and a control plot located in the Sierra Nevada Mountains, CA, USA (Blodgett Forest, 38 degrees 53' N, 120 degrees 37' W, 1315 ...

Brillouin spectroscopy has been used to study the effect of the deposition temperature on the surface acoustic wave SAW propagation velocity of aluminum nitride AlN films. The results show a dependence of the SAW propagation velocity on the growth temperature of AlN films. The highest value of acoustic velocity was obtained for the film elaborated without heating. Structural characterization of...

In pipeline transportation of slurry, the existing calculation models of critical deposition velocity face the problem of different model forms only suitable for specific conditions. To address this problem, this paper uses improved “shuffled frog leaping algorithm” (SFLA) to optimize the parameters of the computational model in order to calculate critical deposition velocity. This has been fou...