Azetidinyl substituents have been recently used to improve the fluorescence quantum yield of several classes of fluorophores. Herein, we demonstrate that other useful photochemical processes can be modulated using this strategy. In particular, we prepared and measured the quantum yield of photorelease of a series of 7-azetidinyl-4-methyl coumarin esters and compared it to their 7diethylamino an...

We present the first simultaneous measurements of HOx, NOx, and Clx radicals in the middle stratosphere obtained during a balloon flight at 34 N in September 1989, along with calculations from a photochemical model, to show that NOx catalytic cycles dominate loss of ozone (O3) for altitudes between 24 and 38 km; the observed abundance of ClO is lower than that expected for altitudes above 30 km...

To develop sound air quality plans, regional authorities should have instruments that link the complex behaviour of pollutants both in time and space with costs of emission reduction. The problem is particularly important for ground level ozone which forms kilometres away, hours later from the emission of its precursors. To approach this problem, a method (1) to identify local pollutant-precurs...

The Longuet-Higgins phase change theorem is used to show that, in certain photochemical reactions, a single product is formed via a conical intersection. The cis-trans isomerization around the double bond in the formaldiminium cation and vinylamine are shown to be possible examples. This situation is expected to hold when the reactant can be converted to the product via two distinct elementary ...

15 We analyze a photochemical smog episode to understand the oxidative capacity and radical chemistry of the polluted atmosphere in Hong Kong and the Pearl River Delta (PRD) region. A photochemical box model based on the Master Chemical Mechanism (MCM v3.2) is constrained by an intensive set of field observations to elucidate the budgets of ROX (ROX=OH+HO2+RO2) and NO3 radicals. Highly abundant...

Hepatitis B virus (HBV) is a common and widespread infection that poses a serious threat among carriers for the development of life-threatening liver diseases. The aim of the present study was to evaluate the effectiveness of the riboflavin photochemical method in inactivating duck hepatitis B virus (DHBV) in plasma via an animal model. Forty ducks were selected and randomly divided into the ex...

A six-level quasi-geostrophic model including radiative and photochemical processes in the manner suggested by Lindaen and Goody is run from a state of joint radiative-photochemical equilibrium for midwinter conditions. The spectral method is used to integrate the equations where all dependent variables are represented by a set of spherical harmonics with east-west wave numbers 0, 1, 2, 3, and ...

[1] During the CalNex (California Research at the Nexus of Air Quality and Climate Change) field study in May–June 2010, measurements of volatile organic compounds (VOCs) were performed in the Los Angeles (LA) basin onboard a NOAA research aircraft and at a ground site located in Pasadena. A weekday-weekend effect in ozone, caused by lower NOx emissions due to reduced diesel truck traffic in th...

[1] This paper is based on alkyl nitrate measurements made over the North Atlantic as part of the International Consortium for Research on Atmospheric Transport and Transformation (ICARTT). The focus is on the analysis of air samples collected on the UK BAe-146 aircraft during the Intercontinental Transport of Ozone and Precursors (ITOP) project, but air samples collected on board the NASA DC-8...