Oxygen Carbon Dioxide Atmospheres Research Articles

Effects of carbon dioxide addition on diesel spray flame characteristics in oxygen-carbon dioxide atmospheres

In order to study the diesel flame combustion characteristics in the different OCD atmospheres, a DCER model is proposed, which considers the air entrainment rates and the influences of OCD atmospheres. Firstly, FLOL and X+ calculation formulas are obtained. Furthermore, the chemical model of primary reference fuel (n-heptane) and the geometric structure of CVCC are established. Secondly, to verify the model, the experiment is carried out in a visualized CVCC and processes of flame combustion are captured by a high-speed camera. Furthermore, results of flame structure, temperature maps, FLOL and FNL are discussed at 3 MPa and 850 K in air, 50%O2/50%CO2(50 CDC), 43 CDC and 35 CDC, respectively. Through comparison between the DCER model simulation and the experiment, the conclusions are as follows: combustioncharacteristicsare quite different in several atmospheres. Comparing the temperature maps, there is an obvious distinction in the upper part of the flame upstream region in 50 CDC and 43 CDC. The DCER model can predict the diesel FLOL in 50 CDC, 43 CDC and 35 CDC with errors of 5.35%, 6.47% and 3.65%, respectively. The changes of OCD have a great influence on FLOL and FNL. With CDC decreasing, FLOL and FNL decline stably and the maximum of FNL appears earlier.

The stimulating and inhibitory effect of monoquaternary ammonium compounds on decamethonium uptake by rat kidney cortex slices

Decamethonium is concentrated as the unchanged compound in rat kidney cortex slices incubated (oxygen-carbon dioxide atmosphere 95:5 v/v %) in Krebs-Ringer bicarbonate medium (37°, pH 7.4) containing [ 14C]-decamethonium. Decamethonium uptake was a saturable and metabolically dependent process. When added to medium at relatively low concentrations carbamoylcholine, choline, neostigmine and tetraethylammonium stimulated 1 hr uptake of decamethonium(2 × 10 −6 M), whereas these monoquaternary ammonium compounds at higher concentrations inhibited uptake. Initial decamethonium uptake (5 min) was increased when slices were preincubated (90 min) with a monoquaternary ammonium compound (without decamethonium) before transfer to a medium containing only decamethonium (2 × 10 −6 M). This suggests that stimulation is related to the presence of monoquaternary ammonium compounds in the slices. No decamethonium efflux (30 min) occurred from slices preincubated (1 hr) with decamethonium (2 × 10 −6 M), which means that stimulation cannot be attributed to inhibition of decamethonium efflux by monoquaternary ammonium compounds. The stimulation phenomenon can be interpreted as an example of substrate-facilitated carrier transport, which implies that efflux of monoquaternary ammonium compounds accelerates decamethonium influx. This interpretation is consistent with the conclusion from the experiments on mutual inhibition that the polymethylene-bisquaternary ammonium compound decamethonium and the above monoquaternary ammonium compounds share a common carrier mechanism.