نتایج جستجو برای: 100 and 200 ppb and no2 gas at concentrations 60
تعداد نتایج: 17299788 فیلتر نتایج به سال:
lichens are composite organisms formed by a fungus and a green alga and / or a blue-green bacterium. they are recognized as being very sensitive to atmospheric pollution and respond to factors that influence human and environmental healths. since 1860, lichen has been identified as a biological indicator to detect air pollution in great britain and europe. lichens have the high sensitivityto ni...
Eleven mild atopic asthmatic patients were exposed for 6 h, in randomized order, to air, 100 ppb O3, 200 ppb NO2, and 100 ppb O3 + 200 ppb NO2, followed immediately by bronchial allergen challenge. Subsequently 10 of these patients were exposed for 3 h to air, 200 ppb O3, 400 ppb NO2, and 200 ppb O3 + 400 ppb NO2, followed immediately by bronchial allergen challenge. All exposures were carried ...
in the present study, the effect of e-64 at different concentrations (0.5, 1, 5 and 10 µm) added to (1) the ivm medium on oocyte nuclear maturation and developmental competence of ovine oocytes, and (2) to the ivc medium on embryonic development of ovine embryos were investigated.
in the present work, a simple and sensitive method was developed for determination of morphine and heroin using gold nanoparticles as resonance rayleigh scattering (rrs) and colorimetric technique’s probe. synthesized gold nanoparticles by sodium citrate reduction method have a negative charge layer on their surfaces because of self-assembled citrate anions on their surface. binding of morphin...
Individual PAH are shown to undergo chemical transformation when exposed to gases such as NO2, O3 and SO3. The possibility of artifact formation during sampling in stacks and in ambient air is discussed. PAH on soot, formed in a smoke gas generator, and exposed to NO chi and SO chi in a thermostated oven were degraded as a result of the sampling technique. Addition of NO2 (1 ppm) or gaseous HNO...
BACKGROUND Recent studies have suggested that air pollutants resulting from vehicle exhaust emissions and burning of fossil fuels, either in combination or individually, may enhance the airway response of asthmatic subjects to inhaled allergen. It was hypothesised that the airway response to inhaled allergen after exposure to a combination of 400 ppb nitrogen dioxide (NO2) and 200 ppb sulphur d...
BACKGROUND Nitrogen dioxide (NO2), a ubiquitous atmospheric pollutant, may enhance the asthmatic response to allergens through eosinophilic activation in the airways. However, the effect of NO2 on inflammation without allergen exposure is poorly studied. OBJECTIVES We investigated whether repeated peaks of NO2, at various realistic concentrations, induce changes in airway inflammation in asth...
The detection of NO2 in ambient air requires sensors that are capable of measuring concentrations in the low ppb range at high resolution. Using a cyclic measuring technique, a resolution below 1 ppb has been attained at concentrations below 10 ppb with a Surface Acoustic Wave (SAW) sensor. This technique requires that the SAW sensor is first put into a defined initial state by a combination of...
Ground-based Multi-Axis Differential Optical Absorption Spectroscopy (MAX-DOAS) measurements of nitrous acid (HONO) and its precursor NO2 (nitrogen dioxide) as well as aerosols have been performed daily in Beijing city centre (39.98 N, 116.38 E) from July 2008 to April 2009 and at the suburban site of Xianghe (39.75 N, 116.96 E) located∼ 60 km east of Beijing from March 2010 to December 2012. T...
this is an original study on the effect of a polyisobutylene – polydimethylsiloxane (pibpdms) block copolymer modifier used as an interfacial active agent on the dynamics behaviour of single newtonian drops suspended in a polyisobutylene (pib) newtonian matrix. the results were divided in two sections. the first part included the experiments carried out on the non-modified and 2% block cop...
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