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Current needs for reduced emissions and improved efficiency have motivated the study of the combustion of novel, oxygenated fuels. The scope of the present work is to experimentally and num...

Matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs) are thought to be predominant proteases and protease inhibitors involved in the pathogenesis of inflammatory bowel diseases (IBD) through their ability to remodel the extracellular matrix (ECM) in response to inflammatory stimuli and by their immunomodulating effects. An imbalance between MMPs and TIMPs has been linked with acute and chronic inflammation and aberrant tissue remodeling, as seen in IBD. Moreover, recurrent phases of tissue destruction and subsequent tissue repair can cause serious complications in IBD patients such as fistulas and fibrosis. The aims of this review are (i) to summarize current literature on genetic association, mRNA, and protein expression studies with regard to MMPs and TIMPs in IBD patients and various animal models, including those with transgenic and knockout mice; (ii) to compare biochemical and molecular biological data in humans with those obtained in animal model studies and (iii) to critically evaluate and translate how this knowledge may be used in practical terms to understand better the pathophysiology and mechanisms operating in IBD and to apply this for improvement of clinical outcomes at diagnostic, prognostic and therapeutic levels.

Propanal (C2H5CHO) is a crucial intermediate oxygenated species in hydrocarbons and oxygenated fuels combustion, thus motivating a better understanding of its kinetics. In this study, two premixed at flames of propanal/hydrogen/oxygen/argon, a stoichiometric and a rich, are stabilized at low pressure (27 mbar) on a burner. Species mole fraction profiles have been measured by molecular beam mass spectrometry (MBMS) for the reactants, products, and intermediate species: C2H5CHO (propanal), H2, O2, Ar, H, OH, HO2, CO, CO2, H2O, CH3, CH4, CH2O (formaldehyde), CH2CO (ketene), CH3CO (acetyl radical), C2H2 (acetylene), C2H4 (ethylene), and C2H6 (ethane). The mechanism from the Universite catholique de Louvain (UCL) has been extended to the kinetics of propanal and its reliability has been validated against both of these propanal flames, at low pressure and in the temperature range up to 1530 K. According to the model, the main propanal consumption channel produces the ethyl radical (C2H5). This last radi...

Experimental structures of two dimethoxymethane/oxygen/argon flames at equivalence ratios of phi = 0.24 and 1.72 have been studied by mass spectrometry. The detected species throughout the flame thickness were H-2, CH3, CH4, H2O, C2H2, CO, CH2O, CH3O, O-2, Ar, CO2, C2H4O2, and C3H8O2. The aim of this work was to extend an original model for ethylene combustion by building a sub-mechanism taking into account the formation and the consumption of oxygenated species involved in dimethoxymethane oxidation. By using kinetic data from the literature, the authors elaborated a new mechanism containing 480 reactions involving 90 chemical species in order to simulate these dimethoxymethane flames. The mechanism provides numerical results, which are in good agreement with experimental data for all species detected in both flames. Whatever the equivalence ratio of the flame, the two main degradation pathways of dimethoxymethane are the same: CH3OCH2OCH3 -> CH3OCH2OCH2 -> CH3OCH2 -> CH2O and CH3OCH2OCH3 -> CH3OCHOCH3 -> CH3OCHO -> CH3OCO -> CH3O -> CH2O, with the first being the fastest.

The main objectives of this research consist in achieving both experimental and numerical studies of the combustion of several flames using acetaldehyde as a fuel. Experimental mole fraction profiles of chemical species (stable, radical, and intermediates) have been measured in three CH3CHO/O-2/Ar flat premixed flames stabilized at low pressure (50 mbar) and with equivalence ratios equal to 0.75, 1, and 1.25, respectively. The experimental setup used to determine the structure of one-dimensional laminar premixed flames consists of a molecular beam mass spectrometer system (MBMS) combined with electron impact ionization (EI). The reaction mechanisms proposed by Yasunaga et al. (2007) and by Marinov (1999) are tested by comparison of model predictions with experimental results. The results show that modeling predicts reactants and products mole fraction profiles reasonably well, but significant differences for many intermediate species remain. In order to improve the predictions for these intermediate species, several improvements on the Marinov's mechanism are suggested. They ensure a reasonably good modeling of the acetaldehyde flame structures.

By using molecular beam sampling mass spectrometry, the structure of a NH3/H-2/O-2/Ar flat premixed flame burning at 50 mbar and with an equivalence ratio equals to one has been determined. Simulated mole fraction profiles have been obtained by using the kinetic mechanisms of Konnov (2000), Bian et al. (1990), Lindstedt et al. (1994), and Smith (1999), but only the first two give results in agreement with the experimental ones. Furthermore, an initial study on a spark ignition engine has been performed to define which parameters must be applied to reach the best possible efficiency and reduce the formation of pollutants when ammonia is used as fuel in engines.

One-dimensional benzene-oxygen-argon (11.5mol% C6H6, 43.2mol% O-2 and 45.3mol% Ar) and benzene- acetylene- oxygen- argon (10.7mol % C6H6, 2.6mol % C2H2, 43.2mol % O-2 and 43.5mol% Ar) flames with an equivalence ratio of 2 were stabilized at low pressure (45 mbar) on a flat flame burner. Gas sampling was achieved by a conical quartz nozzle, at different positions of the flame. Identification and monitoring of chemical species was performed by Molecular Beam Mass Spectrometry (MBMS). Every chemical species was analyzed in both flames, under similar conditions, in order to perform a reliable calibration and a direct comparison. Experimental results and their comparison to simulated data provide interesting clues to evaluate more precisely the role of acetylene in hydrocarbon and PAH production.

Experimental mole fractions profiles of stable species and radicals are reported for a stoichiometric ethanol laminar premixed flame C2H5OH/O-2/Ar burning at 50 mbar. Different mechanisms are tested by comparison of model predictions with experimental results. The results show that some ethanol mechanisms predict reasonably well reactants and products profiles but significant differences for many intermediate species remain.

Alkaline encrusted pyelitis is an infectious disease characterised by encrustations in the wall of the upper urinary tract, surrounded by severe inflammation. Destruction of native kidneys and kidney grafts may occur, resulting in end stage renal failure. Corynebacterium group D2, an urea splitting microorganism, is nearly exclusively associated with this disease. The most important predisposing factors are previous urological procedures and an immunosuppressed state. In a suggestive clinical context, diagnosis should be made with unenhanced computed tomography findings and bacteriologic isolation of the responsible microorganism. The treatment is threefold: appropriate antibiotic therapy, by preference with glycopeptides, acidification of urine and chemolysis, and if needed, surgical removal of encrustations. We report the case of a patient who was diagnosed with this rare condition and could escape maintenance dialysis after correct diagnosis was made and conservative treatment was started using antibiotics and combined oral and local acidification.

Molecular beam mass spectrometry (MBMS) and gas chromatography (GC) are complementary methods that provide a detailed description of flame structures. MBMS can measure most stable and reactive species but mass overlapping (isomers, species at same m/e), isotopic, and ionic fragmentation interferences can be solved by using GC. To improve species identification, an experimental technique coupling both mass spectrometry and GC is developed. Rich flat premixed ethylene/oxygen/argon flames (phi=2.25 and 2.50) have been investigated by both methods. After adequate calibrations, mole fraction profiles of several species measured by both techniques agree very well, but for methane, allene, propyne, and benzene, concentrations in burnt gases are somewhat larger when using GC than when using MBMS. C2H6, C2H4O, C3H6, and C3H8, which have similar masses as CH2O, CO2 or C3H8, CH2CO, and CO2, respectively, have been identified, separated, and calibrated by GC, which confirms that GC and MBMS are complementary techniques.

Lean isobutane and n-butane hat lean flames burning at low pressure have been investigated by means of molecular beam mass spectrometry. Profiles of stable, atomic and radical species have been measured as well as temperature. Acetone and butene occur as intermediates in significant amount. - In isobutane flames the production of both acetone (C3H6O) and butene (C4H8) is ascribed to direct reactions of butyl radicals t-C4H9 + O --> C3H6O + CH3 C4H9 + H, OH --> C4H8 + H-2, H2O t-C4H9 --> C4H8 + H - In n-butane flames, acetone is not produced and butene is accounted for along radical reactions C4H9 + H, OH --> C4H8 + H-2, H2O The occurrence of radical-radical reactions in higher hydrocarbons flames cannot be neglected and supplements the usual thermal decomposition reaction (beta-scission) in the detailed combustion mechanisms.

A direct stiffness method of analyzing the elastic ftexural-torsional buckling of rigid-jointed plane frames composed of l-section members and subjected to in-plane loads is presented. The in-plane stiffness matrix and the fixed-end resultants are obtained from the member stiffness matrices derived from the in-plane differential equations. These member stiffness matrices are assembled and solved, and their solutions are used to linearize the flexural-torsional buckling equations. The out-of-plane member stiffness matrices are then obtained numerically from the buckling equations by the method of finite integrals. The out-of-plane frame -stiffness matrix is assembled, and the critical loads are obtained when its determinant is zero. A computer program is developed which carries out either a first- or second-order in-plane analysis, and then determines the flexural-torsional buckling loads. The effects of in-plane deformations prior to buckling can be included. Very good agreement is obtained betwe...

Using a mass spectrometry associated with molecular beam sampling (MBMS), the complete structure of a NH3 seeded, rich H-2/O2/Ar flat flame (phi = 1.91) has been determined. A recent simplified model for the ammonia oxidation has been tested and accounts for the experimental results. In the investigated temperature range (500-1200 K) current existing models do not predict well the experimental results and the discrepancies can be ascribed to the estimates of the rate coefficients of the processes NH + O2, NH(i) + H and NH + NO. This experimental work performed under rich conditions reinforces the validity of the simplified model already tested in lean and stoichiometric conditions.