نتایج جستجو برای: nitrogen oxides

تعداد نتایج: 136750  

Journal: :The American journal of physiology 1999
M J Miller M Sandoval

Nitric oxide (NO) synthesis is markedly augmented in states of inflammation, largely due to the expression of inducible nitric oxide synthase (iNOS). Although NO has anti-inflammatory consequences under basal conditions, it remains enigmatic as to why NO displays proinflammatory characteristics in chronic inflammation. Either the anti-inflammatory actions are weak and of little consequence or, ...

2007
Jan Koop Olaf Deutschmann

The removal of nitrogen oxides emitted by diesel and lean burn engines is one of the most important targets in catalytic exhaust aftertreatment research. Besides the selective catalytic reduction (SCR) reaction with ammonia the most promising approach is the NOx Storage and Reduction Catalyst (NSR) which utilizes the nitrogen oxides storage on barium sites to form nitrates during the lean phase...

2014
Pandurangappa Malingappa Venkataramanappa Yarradoddappa

A new chemosensor has been used to monitor atmospheric nitrogen oxides [NO + NO2] at parts per billion (ppb) level. It is based on the catalytic reaction of nitrogen oxides with rhodamine B hydrazide (RBH) to produce a colored compound through the hydrolysis of the amide bond of the molecule. A simple colorimeter has been used to monitor atmospheric nitrogen dioxide at ppb level. The air sample...

2000
A. Richter J. P. Burrows

Nitrogen oxides play an important role in the chemistry of earth’s atmosphere. In the troposphere, they provide the only chemical source for ozone, arguably the most important radical in the lower atmosphere. Nitrogen oxides are central in the formation of photochemical smog in the industrialised countries and also in regions with intense biomass burning. In addition to its relevance to troposp...

Journal: :Biochemical Society transactions 2011
Lisa Y Stein Martin G Klotz

Nitrous oxide, a potent greenhouse gas and ozone-depleting molecule, continues to accumulate in the atmosphere as a product of anthropogenic activities and land-use change. Nitrogen oxides are intermediates of nitrification and denitrification and are released as terminal products under conditions such as high nitrogen load and low oxygen tension among other factors. The rapid completion and pu...

2013
E. C. Browne R. C. Cohen

In contrast with the textbook view of remote chemistry where HNO3 formation is the primary sink of nitrogen oxides, recent theoretical analyses show that formation of RONO2 (6ANs) from isoprene and other terpene precursors is the primary net chemical loss of nitrogen oxides over the remote continents where the concentration of nitrogen oxides is low. This then increases the prominence of questi...

Journal: :The Journal of Zhytomyr State Technological University. Series: Engineering 2018

2016
Mary Ann Liebert Capilla Roma Carmen Capilla

This paper presents the application of feed-forward multilayer perceptron networks to forecast hourly nitrogen oxides levels 24 hours in advance. Input data were meteorological variables, average hourly traffic and nitrogen oxides hourly levels. The introduction of four periodic components (sine and cosine terms for the daily and weekly cycles) was analyzed in order to improve the models’ predi...

2006
S. S. Brown W. P. Dubé H. D. Osthoff D. E. Wolfe W. M. Angevine

The shallow mixing depth and vertical stratification of the lowest levels of the atmosphere at night has implications for the chemistry of nitrogen oxides emitted from the surface. Here we report vertical profiles of NO3, N2O5 and O3 measured from in-situ instruments on a movable carriage on a 300 m tower. The study offers high-resolution (<1 m) vertical distributions of both NO3 and N2O5 and s...

2007
A. L. P. Rotondaro R. T. Laaksonen S. P. Singh

The nitrogen concentration of ultrathin gate oxides (sub-1.3 nm) was varied in a wide range (from 13 % to 23 %). The threshold voltage and the channel carrier mobility of advanced 65 nm technology CMOSFET transistors fabricated with these oxides were analyzed. It was observed that increasing the nitrogen concentration in the gate oxide results in a negative shift of the threshold voltage for bo...

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