● Deactivation of Diesel Catalyst Abstract: The first diesel catalysts, introduced in 1970s for underground mining applications, were simple oxidation catalysts designed for conversion of CO and HC. These catalysts gradually evolved into the modern diesel oxidation catalysts, optimized for PM emission reduction. Future requirements for NOx emission reduction from diesel engines call for new cat...

In airsheds that contain high volatile organic compounds (VOCs) and low NOx (=NO+NO2) concentrations, ozone (O3) production may be significantly suppressed by NOx reactions that lead to the formation of organic nitrates. O3 and its precursors (VOCs and NOx) ambient levels simulated using a regional-scale photochemical model, called Multiscale Air Quality Simulation Platform, are analyzed and co...

Section S1 The section describes modifications we implemented to the CLM v4.5 model for better simulating the soil NOx emissions and also reducing the model LAI overestimation. These include addition of soil NOx emission and NH3 volatilization 10 processes, and an improved parameterization of nitrogen uptake by plants. We evaluate the CLM simulated results with satellite LAI observations and so...

The U.S. faces the difficult dual challenge of reducing the consumption of transportation fuels and improving air quality. Lean burn gasoline, diesel, and natural gas engines are of interest because they are more fuel efficient than conventional stoichiometric gasoline engines. Unfortunately, the unconverted oxygen in the exhaust prevents the use of the conventional three-way catalytic converte...

Nitrogen oxides (NOx) play key roles in atmospheric chemistry, air pollution, and climate. While the largest fraction of these reactive gases is released by anthropogenic emission sources, a significant amount can be attributed to vegetation fires. In this study, NO2 from GOME2 on board EUMETSAT’s MetOp-A and OMI on board NASA’s Aura as well as fire radiative power (FRP) from the measurements o...

Ozone pollution in the Southeast US involves complex chemistry driven by emissions of anthropogenic nitrogen oxide radicals (NOx ≡NO+NO2) and biogenic isoprene. Model estimates of surface ozone concentrations tend to be biased high in the region and this is of concern for designing effective emission control strategies to meet air quality standards. We use detailed chemical observations from th...

[1] The impact of nitrogen oxide (NOx) emission reductions from major point sources on the key physical and chemical processes contributing to ozone formation and accumulation is studied, and the extent of change in the chemical regime is examined using selected photochemical indicators in the eastern United States. The Community Multiscale Air Quality (CMAQ) chemical-transport model, equipped ...

In atherosclerosis, oxidative stress-induced vascular smooth muscle cells (SMCs) dysfunction is partially mediated by up-regulated NADPH oxidase (Nox); the mechanisms of enzyme regulation are not entirely defined. CCAAT/enhancer-binding proteins (C/EBP) regulate cellular proliferation and differentiation, and the expression of many inflammatory and immune genes. We aimed at elucidating the role...

Large-scale changes in ozone precursor emissions affect ozone directly in the short term, and also affect methane, which in turn causes long-term changes in ozone that affect surface ozone air quality. Here we assess the effects of changes in ozone precursor emissions on the longterm change in surface ozone via methane, as a function of the emission region, by modeling 10% reductions in anthrop...

Coflow and counterflow methane–air flames are simulated over a complete partially premixed regime in order to characterize the effects of dominant combustion modes (i.e., single-, two-, and three-stage combustion) on NOx emissions. Simulations employ a comprehensive numerical model that uses detailed descriptions of transport and chemistry (GRI-2.11 mechanism) and includes radiation effects. It...