Kinetics of isopropanol decomposition and reaction with H atoms from shock tube experiments and rate constant optimization using the method of uncertainty minimization using polynomial chaos expansions (MUM-PCE)
INTERNATIONAL JOURNAL OF CHEMICAL KINETICS
Authors: Mertens, Laura A.; Manion, Jeffrey A.
Abstract
We have used the single-pulse shock tube technique with postshock GC/MS product analysis to investigate the mechanism and kinetics of the unimolecular decomposition of isopropanol, a potential biofuel, and of its reaction with H atoms at 918-1212 K and 183-484 kPa. Experiments employed dilute mixtures in argon of isopropanol, a radical scavenger, and, for H-atom studies, two different thermal precursors of H. Without an added H source, isopropanol decomposes in our studies predominantly by molecular dehydration. Added H atoms significantly augment decomposition, mainly by abstraction of the tertiary and primary hydrogens, reactions that, respectively, lead to acetone and propene as stable organic products. Traces of acetaldehyde were observed in some experiments above approximate to 1100 K and establish branching limits for minor decomposition pathways. To quantitatively account for secondary chemistry and optimize rate constants of interest, we employed the method of uncertainty minimization using polynomial chaos expansions (MUM-PCE) to carry out a unified analysis of all datasets using a chemical model-based originally on JetSurF 2.0. We find:k(isopropanol -> propene + H2O) = 10((13.87 +/- 0.69))exp(-(33 099 +/- 979) K/T) s(-1)at 979-1212 K and 286-484 kPa, with a factor of two uncertainty (2 sigma), including systematic errors. For H atom reactions, optimization yields:k(H + isopropanol -> H-2+p-C3H6OH)( )= 10((6.25 +/- 0.42))T(2.54)exp(-(3993 +/- 1028) K /T) cm(3)mol(-1)s(-1)andk(H + isopropanol -> H-2+t-C3H6OH)( )= 10((5.83 +/- 0.37))T(2.40)exp(-(1507 +/- 957) K /T) cm(3)mol(-1)s(-1)at 918-1142 K and 183-323 kPa. We compare our measured rate constants with estimates used in current combustion models and discuss how hydrocarbon functionalization with an OH group affects H abstraction rates.
Practical management of C3 glomerulopathy and Ig-mediated MPGN: facts and uncertainties
KIDNEY INTERNATIONAL
Authors: Fakhouri, Fadi; Le Quintrec, Moglie; Fremeaux-Bacchi, Veronique
Abstract
In recent years, a substantial body of experimental and clinical work has been devoted to C3 glomerulopathy and Ig-mediated membranoproliferative glomerulonephritis. Despite the rapid accumulation of data, several uncertainties about these 2 rare forms of nephropathies persist. They concern their pathophysiology, classification, clinical course, relevance of biomarkers and of pathology findings, and assessment of the efficacy of the available therapies. The present review discusses the impact of these uncertainties on the clinical management of patients.