Accuracy of photochemical air quality model results depends not only on the accuracy of the meteorological fields supplied to the model, but also the frequency that those fields are updated. Tests in two and three dimension, with and without chemistry, were run to identify errors that can arise due to the frequency that models are linked (or coupled) to time varying meteorological fields. In ap...

This study investigates the improvement of ozone (O3) simulations in the Mexico City basin using a threedimensional variational (3DVAR) data assimilation system in meteorological simulations during the MCMA-2003 field measurement campaign. Meteorological simulations from the NCAR/Penn State mesoscale model (MM5) are used to drive photochemical simulations with the Comprehensive Air Quality Mode...

The direct reaction kinetic method of low pressure fast discharge flow (DF) with resonance fluorescence monitoring of OH (RF) has been applied to determine rate coefficients for the overall reactions OH + C2H5F (EtF) (1) and OH + CH3C(O)F (AcF) (2). Acetyl fluoride reacts slowly with the hydroxyl radical, the rate coefficient at laboratory temperature is k2(300 K) = (0.74 ± 0.05) × 10(-14) cm(3...

Introduction Blue light is a part of the spectrum with the highest energy content, which can reach the retina. The damage that it can cause to the retina is called photochemical or blue-light retinal injury. For the retinal injury assessment of the photochemical and aphakic retinal hazards in the wavelength range of 300-700 nm, use of effective spectral radiance limits (W.m-2.sr-1) seems to be...

This paper is presented to make both ocular symptoms and signs clear, by means of some experiments on the eye affected by photochemical air pollution. This paper summarizes three experiments, these results and discussion. The first series of experiments were performed in order to research eye irritation caused by photochemical synthetic irritants. They proved the threshold of eye irritation and...

the photocatalytic degradation of a common analgesic (acetaminophen) with titanium dioxide irradiated with low energy ultraviolet light (365 nm) was studied in order to determine the effect of several parameters such as catalyst’s weight, photochemical effect, and initial concentration. the results indicate that acetaminophen is degraded in the order of 4% by the photochemical effect. the pres...

A simple model for the early events in visual pigments and bacteriorhodopsin is proposed. The model makes use of the likelihood that a negatively charged amino acid forms a salt bridge with the positively charged nitrogen of the retinylic chromophore. The photochemical event is a cis-trans isomerization in visual pigments and a trans-cis isomerization in bacteriorhodopsin, which in each case cl...

The photochemical breaking of the peptide (amide) bond is investigated by x-ray absorption spectroscopy at the C 1s, N 1s, and O 1s edges. Interestingly, the product of the photochemical reaction leaves a clear and universal signature, i.e. two well-defined * peaks at the N 1s edge which grow while the * peak of the peptide bond shrinks. This signature is found for a wide variety of amides, r...

This study aimed to qualify photosafety screening on the basis of photochemical and pharmacokinetic (PK) data on dermally applied chemicals. Six benzophenone derivatives (BZPs) were selected as model compounds, and in vitro photochemical/phototoxic characterization and dermal cassette-dosing PK study were carried out. For comparison, an in vivo phototoxicity test was also conducted. All of the ...