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- Cung, T. -T., et al.
(författare)
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Cyclosporine before PCI in Patients with Acute Myocardial Infarction
- 2015
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Ingår i: New England Journal of Medicine. - 0028-4793. ; 373:11, s. 1021-1031
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND Experimental and clinical evidence suggests that cyclosporine may attenuate reperfusion injury and reduce myocardial infarct size. We aimed to test whether cyclosporine would improve clinical outcomes and prevent adverse left ventricular remodeling. METHODS In a multicenter, double-blind, randomized trial, we assigned 970 patients with an acute anterior ST-segment elevation myocardial infarction (STEMI) who were undergoing percutaneous coronary intervention (PCI) within 12 hours after symptom onset and who had complete occlusion of the culprit coronary artery to receive a bolus injection of cyclosporine (administered intravenously at a dose of 2.5 mg per kilogram of body weight) or matching placebo before coronary recanalization. The primary outcome was a composite of death from any cause, worsening of heart failure during the initial hospitalization, rehospitalization for heart failure, or adverse left ventricular remodeling at 1 year. Adverse left ventricular remodeling was defined as an increase of 15% or more in the left ventricular end-diastolic volume. RESULTS A total of 395 patients in the cyclosporine group and 396 in the placebo group received the assigned study drug and had data that could be evaluated for the primary outcome at 1 year. The rate of the primary outcome was 59.0% in the cyclosporine group and 58.1% in the control group (odds ratio, 1.04; 95% confidence interval, 0.78 to 1.39; P = 0.77). Cyclosporine did not reduce the incidence of the separate clinical components of the primary outcome or other events, including recurrent infarction, unstable angina, and stroke. No significant difference in the safety profile was observed between the two treatment groups. CONCLUSIONS In patients with anterior STEMI who had been referred for primary PCI, intravenous cyclosporine did not result in better clinical outcomes than those with placebo and did not prevent adverse left ventricular remodeling at 1 year. (Funded by the French Ministry of Health and NeuroVive Pharmaceutical; CIRCUS ClinicalTrials.gov number, NCT01502774; EudraCT number, 2009-013713-99.)
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- Elbaz, A. M., et al.
(författare)
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An experimental/numerical investigation of the role of the quarl in enhancing the blowout limits of swirl-stabilized turbulent non-premixed flames
- 2019
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Ingår i: Fuel. - : Elsevier BV. - 0016-2361. ; 236, s. 1226-1242
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Tidskriftsartikel (refereegranskat)abstract
- The blowout limits of methane/air non-premixed swirl-stabilized flames were measured with and without quarl. The addition of a quarl significantly enhances the flame blowout limits. The transition from attached flame to blowout was mapped. To explore the role of the quarl, a series of OH-PLIF/PIV experiments, coupled with large eddy simulations (LES) using a transported probability density function (PDF) model, were carried out on flames with and without quarl over a wide range of fuel jet velocity, Uf. The results show that the mean flow field is characterized by two recirculation zones. The existence of the quarl enhances this flow field by triggering a larger scale of reversal flow, penetrating deeply upstream into the quarl. This results in much earlier fuel, extending down into the air tube, where a diffusion flame is stabilized around the stoichiometric mixture contour and locally low scalar dissipation rates. The relative delay in fuel/air mixing in non-quarl flames results in a locally strong scalar dissipation rate layer overlapping the stoichiometric mixture contour, and thus, the flame is highly sensitive to local extinction with increasing fuel jet velocity. At high Uf, in the liftoff flame region, the existence of the quarl enhances the jet spreading and a weak recirculation zone around the highly strained jet is observed. Together with fuel jet spreading, partial oxidization of the mixture upstream the lifted flame base creates a wider range of burnable mixture along the axis in the quarl flames. On the contrary, the high scalar dissipation rate and the absence of a recirculation region in the proximity of the fuel nozzle in the non-quarl flame give rise to an earlier blowout.
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- Liu, X., et al.
(författare)
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Effect of burner geometry on swirl stabilized methane/air flames : A joint LES/OH-PLIF/PIV study
- 2017
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Ingår i: Fuel. - : Elsevier BV. - 0016-2361. ; 207, s. 533-546
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Tidskriftsartikel (refereegranskat)abstract
- Large eddy simulation (LES) using a transported PDF model and OH-PLIF/PIV experiments were carried out to investigate the quarl effects on the structures of swirl stabilized methane/air flames. Two different quarls were investigated, one straight cylindrical quarl and one diverging conical quarl. The experiments show that the flames are significantly different with the two quarls. With the straight cylindrical quarl a compact blue flame is observed while with the diverging conical quarl the flame appears to be long and yellow indicating a sooty flame structure. The PIV results show the formation of a stronger flow recirculation inside the diverging conical quarl than that in the straight quarl. LES results reveal further details of the flow and mixing process inside the quarl. The results show that with the diverging quarl vortex breakdown occurs much earlier towards the upstream of the quarl. As a result the fuel is convected into the air flow tube and a diffusion flame is stabilized inside the air flow tube upstream the quarl. With the straight quarl, vortex breakdown occurs at a downstream location in the quarl. The scalar dissipation rate in the shear layer of the fuel jet is high, which prevents the stabilization of a diffusion flame in the proximity of the fuel nozzle; instead, a compact partially premixed flame with two distinct heat release layers is stablized in a downstream region in the quarl, which allows for the fuel and air to mix in the quarl before combustion and a lower formation rate of soot. The results showed that the Eulerian Stochastic Fields transported PDF method can well predict the details of the swirl flame dynamics.
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- Wang, Shixing, et al.
(författare)
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Experimental study and kinetic analysis of the laminar burning velocity of NH3/syngas/air, NH3/CO/air and NH3/H2/air premixed flames at elevated pressures
- 2020
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Ingår i: Combustion and Flame. - : Elsevier BV. - 0010-2180. ; 221, s. 270-287
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Tidskriftsartikel (refereegranskat)abstract
- Mixing ammonia with syngas can be a promising way to overcome the low reactivity of ammonia, allowing it to find usage in IGCC (Integrated Gasification Combined Cycle) systems and gas turbines for power generation. However, fundamental experimental data on laminar burning velocity of NH3/syngas/air are rather scarce, especially at elevated pressures. This information is critical for the development and validation of reaction mechanisms and advances in combustor design. In the present work, measurements of the laminar burning velocities (SL) of NH3/syngas/air, NH3/CO/air, and NH3/H2/air premixed flames were performed by the heat flux method at pressures up to 5 atm, equivalence ratios ranging from 0.7 to 1.6, ammonia mole fractions in the fuel mixture from 0.2 to 1.0 in the NH3/syngas/air mixtures and 0.03–1.0 in the NH3/CO/air mixtures. Several recently published ammonia oxidation mechanisms were tested against the present experimental data. The measurements and predictions of SL exhibit discrepancies especially for NH3/H2/air flames at elevated pressures. The pressure exponent factors, β, characterizing burning velocity at elevated pressure via empirical power-law correlation SL/SL0 = (P/P0)β are extracted from the measured SL and compared with the numerical results. The thermal, diffusion, and chemical effects of blending syngas with ammonia on SL of the mixtures are distinguished, and the dominant role of the adiabatic flame temperature on the variation of the pressure exponent β is discussed. Kinetic modeling and sensitivity analyses showed that reactions of NHi to N2Hi (i = 0–4) species affect the predicted SL under rich conditions. At elevated pressures, these reactions also affect the NO formation via third-body collision reactions and NHi + NO reactions. Even for rich flames, the ammonia consumption is favored with the addition of syngas which also promotes NO formation by enriching the H and OH radical pools and increasing the flame temperature. The addition of hydrogen or carbon monoxide has equally promoting effect on the ammonia decomposition and NOx formation although their flame speed differs a lot.
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