نتایج جستجو برای: ozone o3

تعداد نتایج: 25933  

2007

During October/November 1997, simultaneous observations of NO, HO2 and other species were obtained as part of the SONEX campaign in the upper troposphere. We use these observations, over the North Atlantic (40-60øN), to derive ozone production rates, P(O3), and to examine the relationship between P(O3) and the concentrations of NOx (= NO + NO2) and HOx (= OH + peroxy) radicals. A positive corre...

1999
L. Jaeglé D. J. Jacob W. H. Brune I. C. Faloona D. Tan Y. Kondo G. W. Sachse B. Anderson G. L. Gregory S. Vay H. B. Singh D. R. Blake R. Shetter

During October/November 1997, simultaneous observations of NO, HO2 and other species were obtained as part of the SONEX campaign in the upper troposphere. We use these observations, over the North Atlantic (40-60°N), to derive ozone production rates, P(O3), and to examine the relationship between P(O3) and the concentrations of NOx (= NO + NO2) and HOx (= OH + peroxy) radicals. A positive corre...

Journal: :Acta odontologica latinoamericana : AOL 2010
Jerónimo Tessier Patricia N Rodriguez Fima Lifshitz Silvia M Friedman Eduardo J Lanata

Tooth-whitening agents are available for therapeutic use in the dental office or at home. However, whitening more severe stains, such as those caused by systemic ingestion of tetracycline, constitutes a challenge. The aim of this study was to evaluate, in an experimental model of growing rats, the efficacy of using ozone to lighten tetracycline-stained incisors. At weaning, male Wistar rats (n=...

Journal: :Applied optics 2006
Xiong Liu Kelly Chance Christopher E Sioris Michael J Newchurch Thomas P Kurosu

We present, to the best of our knowledge, a new method to retrieve tropospheric ozone (O3) profiles from ground-based ultraviolet spectroscopic measurements. This method utilizes radiance spectra in the Huggins bands (i.e., 300-340 nm) measured at three off-axis angles (e.g., 45 degrees, 75 degrees, and 85 degrees) normalized to direct-Sun irradiances or zenith-sky radiances with the total colu...

Journal: :Environmental Health Perspectives 2001
C K Wilkins P A Clausen P Wolkoff S T Larsen M Hammer K Larsen V Hansen G D Nielsen

We evaluated the airway irritation of isoprene, isoprene/ozone, and isoprene/ozone/nitrogen dioxide mixtures using a mouse bioassay, from which we calculated sensory irritation, bronchial constriction, and pulmonary irritation. We observed significant sensory irritation (approximately 50% reduction of mean respiratory rate) by dynamically exposing the mice, over 30 min, to mixtures of isoprene ...

Journal: :Journal of the Air & Waste Management Association 2006
Nicole Britigan Ahmad Alshawa Sergey A Nizkorodov

Indoor air purifiers are advertised as safe household products for health-conscious individuals, especially for those suffering from allergies and asthma. However, certain air purifiers produce ozone (O3) during operation, either intentionally or as a byproduct of air ionization. This is a serious concern, because O3 is a criteria air pollutant regulated by health-related federal and state stan...

Journal: :Journal of integrative plant biology 2009
Fitzgerald Booker Russell Muntifering Margaret McGrath Kent Burkey Dennis Decoteau Edwin Fiscus William Manning Sagar Krupa Arthur Chappelka David Grantz

The productivity, product quality and competitive ability of important agricultural and horticultural plants in many regions of the world may be adversely affected by current and anticipated concentrations of ground-level ozone (O3). Exposure to elevated O3 typically results in suppressed photosynthesis, accelerated senescence, decreased growth and lower yields. Various approaches used to evalu...

2015
I. Bordi F. Berrilli E. Pietropaolo

The long-term variability in stratospheric ozone mass mixing ratio (O3) and temperature (T ) from 1979 to 2013 is investigated using the latest reanalysis product delivered by the European Centre for Medium-Range Weather Forecasts (ECMWF), i.e., ERA-Interim. Moreover, using the Mg II index time series for the same time period, the response of the stratosphere to the 11-year Schwabe solar cycle ...

2000
KARL ZELLER

High rural concentrations of ozone (O3) are thought to be stratospheric in origin, advected from upwind urban sources, or photochemically generated locally by natural trace gas emissions. Ozone is known to be transported vertically downward from the above-canopy atmospheric surface layer and destroyed within stomata or on other biological and mineral surfaces. However, here the authors report m...

Journal: :Environmental science & technology 2006
E J Williams F C Fehsenfeld B T Jobson W C Kuster P D Goldan J Stutz W A McClenny

This paper evaluates the accuracy of ozone measurements made by monitors that determine ozone concentrations in ambient air by UV absorption. These monitors are typically used to measure ozone for the purpose of establishing local compliance to air-quality standards. The study was predicated by the concern that commercially available UV absorbance O3 monitors may be subject to interference from...

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