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The supercritical CO2 power cycle (sCO2) is a relatively new technology, which promises to reduce CO2 emissions with potentially higher efficiencies. However, due to challenging conditions posed by supercritical pressures, the ignition phenomena in sCO2 combustion are relatively less understood and studied. The primary objective of the current study is to elucidate ignition processes using homogeneous ignition calculations (HMI) and two-dimensional direct numerical simulations (DNS). To accurately model the supercritical conditions, the employed formulation includes the cubic Peng–Robinson equation of state, mass, and heat flux vectors derived from nonequilibrium thermodynamics and compressible form of governing equations. For selection of a suitable chemical mechanism, HMI calculations are employed to investigate the performance of existing skeletal mechanisms against shock-tube experimental data. The chemical characteristics of ignition are further studied using path flux and sensitivity analysis, with CH3O2 chemistry exhibiting the largest effect on accelerating the ignition process. Different chemical pathways of fuel breakdown are also discussed to aid in interpretation of subsequent DNS case. In the DNS case, autoignition of a two-dimensional mixing layer perturbed with pseudoturbulence is simulated. The ignition is found to be delayed compared to the HMI case, with the ignition kernels forming in a spotty manner. The two phenomena are primarily attributed to variation of scalar dissipation within the mixing layer. The ignition kernels expand and evolve into a tribrachial edge flame propagating along the stoichiometric isosurface. Further investigation on the structure of edge flame revealed an asymmetrical structure, with CH4 molecules being entirely consumed in the triple point region of the flame along the stoichiometric isosurface, and more stable fuels like CO burning in the non-premixed branch of the edge flame. The edge flame propagation speeds are also calculated, with variations found to be correlated with scalar dissipation and upstream progress variable of the reacting mixture. [ABSTRACT FROM AUTHOR]

The supercritical CO2 power cycle (sCO2) is a relatively new technology, which promises to reduce CO2 emissions with potentially higher efficiencies. However, due to challenging conditions posed by supercritical pressures, the ignition phenomena in sCO2 combustion are relatively less understood and studied. The primary objective of the current study is to elucidate ignition processes using homogeneous ignition calculations (HMI) and two-dimensional direct numerical simulations (DNS). To accurately model the supercritical conditions, the employed formulation includes the cubic Peng–Robinson equation of state, mass, and heat flux vectors derived from nonequilibrium thermodynamics and compressible form of governing equations. For selection of a suitable chemical mechanism, HMI calculations are employed to investigate the performance of existing skeletal mechanisms against shock-tube experimental data. The chemical characteristics of ignition are further studied using path flux and sensitivity analysis, with CH3O2 chemistry exhibiting the largest effect on accelerating the ignition process. Different chemical pathways of fuel breakdown are also discussed to aid in interpretation of subsequent DNS case. In the DNS case, autoignition of a two-dimensional mixing layer perturbed with pseudoturbulence is simulated. The ignition is found to be delayed compared to the HMI case, with the ignition kernels forming in a spotty manner. The two phenomena are primarily attributed to variation of scalar dissipation within the mixing layer. The ignition kernels expand and evolve into a tribrachial edge flame propagating along the stoichiometric isosurface. Further investigation on the structure of edge flame revealed an asymmetrical structure, with CH4 molecules being entirely consumed in the triple point region of the flame along the stoichiometric isosurface, and more stable fuels like CO burning in the non-premixed branch of the edge flame. The edge flame propagation speeds are also calculated, with variations found to be correlated with scalar dissipation and upstream progress variable of the reacting mixture. [ABSTRACT FROM AUTHOR]

Some new benzenesulfonylthiourea derivatives substituted with phthalazones (2a- q) were synthesized by refluxing the appropriate 4-aryl-1-oxophthalazin-2(1H)yl benzenesulfonamides with isothiocyanate in dry acetone over anhydrous K2CO3. All the synthesized compounds were characterized on the basis of IR, 1H NMR, MS data and elemental analysis. These synthesized compounds (2a- q) at the dose of 20 mg/kg were tested for antihyperglycemic activity in the glucose-fed hyperglycemic normal rat model and among these compounds 2f and 2m showed modest antihyperglycemic activity. [ABSTRACT FROM AUTHOR]

Nine novel 4-[3-(4-Dimethylamino-phenyl)-5-aryl-4,5-dihydro-pyrazol-1-yl]-benzenesulfonamides ( 2a-i) were synthesized and evaluated for their anti-inflammatory and antiproliferative activities. These compounds ( 2a-i) showed moderate to strong anti-inflammatory activity in carrageenan rat paw oedema test. Compounds 2b, 2d and 2g showing comparable anti-inflammatory activity to that of reference drug celecoxib were evaluated for their ulcerogenic and analgesic activities. The effect of 2b, 2d and 2g on the content of NO, TNF-α and PGE2 in exudates from rat paw stimulated by carrageenan was also evaluated. The compound 2c showed considerable antitumor activities against all 60 human tumor cell lines with effective GI50 (MG-MID) value of 3.63 µM. It exhibited maximum activity against melanoma (LOX IMVI and SK-MEL-5) cancer cell lines with GI50 value less than 2 μM. [ABSTRACT FROM AUTHOR]

Seven novel 6-aryl-2-(p-sulfamoylphenyl)-4,5-dihydropyridazin-3(2H)-ones ( 2a-g) were synthesized by the condensation of appropriate aroylpropionic acid and 4-hydrazinobenzenesulfonamide hydrochloride in ethanol. Structure of all compounds have been elucidated by elemental analysis, IR, 1H NMR, 13C NMR, DEPT and MS spectrscopy. These compounds were tested for their anti-inflammatory activity in carrageenan-induced rat paw edema model. Compound 2b exhibited anti-inflammatory activity comparable to that of celecoxib (at 5 h). Two other compounds 2d and 2g showed promising anti-inflammatory activity (edema reduction more than 80% at 5 h). These compounds ( 2b, 2d and 2g) did not produce any ulceration in gastric region. [ABSTRACT FROM AUTHOR]