The autoignition of the catalytic reaction of hydrogen/air mixtures on thin palladium wires is analyzed in this paper. The reduced heterogeneous kinetics is modeled with a mechanism that includes the dissociative adsorption of both reactants, together with three surface reactions of the Langmuir–Hinshelwood type, and the desorption reaction of the adsorbed product, H2O(s). We show that for the ...

An increased content of hydrogen peroxide (H2O2), a marker of inflammation, has been described in the condensate of exhaled air from adults and children with inflammatory lung disorders, including asthma. However, the normal range of [H2O2] in the exhaled air condensate from healthy children has not been established. Therefore, the aim of this study was to determine the reference range of exhal...

The unsteady flamelet model is applied in numerical simulations of a steady, turbulent, nitrogen-diluted hydrogen-air diffusion flame. An unsteady flamelet is solved interactively with a CFD solver for the turbulent flow and the mixture fraction field. Transient effects occurring in steady jet diffusion flames are discussed in terms of the relevant timescales. It is shown that radiation can be ...

Ammonia, hydrogen sulfide and swine-house dust at continuous aerial levels as high as or higher than those normally encountered in enclosed swine-finishing houses had little or no effect on rate of body-weight gain and respiratory-tract structure of 92 healthy pigs in seven trials. The trials were of 17 to 109 days' duration, involved air pollutants alone and in various combinations and were co...

The regioselective synthesis of allylic hydroperoxide sulfonates by singlet oxygenation at the air-water interface has been found to depend on the concentration of the alkene sulfonate and added calcium salt. The regioselectivity is proposed to originate from an orthogonal alkene relative to the water surface for preferential methyl hydrogen abstraction by airborne singlet oxygen in an ene reac...

We carry out Born-Oppenheimer molecular dynamic simulations to show that the reaction between the smallest Criegee intermediate, CH2OO, and hydrogen sulfide (H2S) at the air/water interface can be observed within few picoseconds. The reaction follows both concerted and stepwise mechanisms with former being the dominant reaction pathway. The concerted reaction proceeds with or without the involv...

Ozone (O3) and hydrogen peroxide (H2O2) volume fractions were calculated using the Master Mechanism (MM) model, author S. Madronich (NCAR, Boulder, CO, USA). MM is an atmospheric “box” model program for calculating the time evolution of atmospheric composition from initial amounts of atmospheric gases under chosen or varying conditions using reaction rate data and other physicochemical paramete...

Autoignition of a hydrogen-air scalar mixing layer in homogeneous turbulence is studied using direct numerical simulation (DNS). An initial counterflow of unmixed nitrogen-diluted hydrogen and heated air is perturbed by two-dimensional homogeneous turbulence. The temperature of the heated airstream is chosen to be 1100 K, which is substantially higher than the crossover temperature at which the...

Average H2O2 (HCHO) mixing ratios measured above the snowpack at South Pole (SP) were 278 pptv (103 pptv) in December 2000 and between 4 and 43 times (1.4–2.6 times) the value estimated from gas-phase photostationary state (PSS) model calculations. The larger difference is realized if dry deposition of both species is included in the model. H2O2 and HCHO fluxes from the snowpack were independen...

Preliminary communication. s The paper will appear shortly in Science, New York, N. S., 1918. All the precautions mentioned in this account were carefully observed in the present investigation. 3 The methods previously used in studying the photosynthesis of aquatic plants are not as accurate as the one here described, nor do previous experiments afford the kind of data needed for our purpose. C...