Combined experimental and kinetic modelling studies of the pathways of propane and n-butane aromatization over H-ZSM-5 catalyst

2006 ◽  
Vol 61 (17) ◽  
pp. 5881-5894 ◽  
Author(s):  
Luong H. Nguyen ◽  
Tanya Vazhnova ◽  
Stan T. Kolaczkowski ◽  
Dmitry B. Lukyanov
Keyword(s):  
Kinetic Modelling ◽  
Modelling Studies ◽  
Butane Aromatization

Chemical Kinetic Modelling of the Evolution of Gaseous Aerosol Precursors Within a Gas Turbine Engine

2004 ◽  
Author(s):  
A. R. Clague ◽  
C. W. Wilson ◽  
M. Pourkashanian ◽  
L. Ma
Keyword(s):  
Gas Turbine ◽  
Kinetic Models ◽  
Kinetic Modelling ◽  
Initial Boundary ◽  
Chemical Kinetic ◽  
Gas Turbine Engine ◽  
Gaseous Product ◽  
Turbine Engine ◽  
Modelling Studies ◽  
The University

A sequence of kinetic models has been developed to simulate the chemical processes occurring throughout the hot section of a modern gas turbine engine. The work was performed as part of the EU funded PARTEMIS programme, which was designed to investigate the effect of both engine condition and fuel sulphur content on the production of gaseous aerosol precursor such as SO3, H2SO4 and HONO. For the PARTEMIS programme, a Hot End Simulator (HES) was designed to recreate the thermodynamic profile through which the hot gases pass after leaving the combustor. Combustion rig tests were performed in which the concentrations of gaseous product species were measured at the exits of both the combustor and the HES. These measurements were used to validate the kinetic models. The combustor was modelled by a sequence of five perfectly stirred reactors, using the Combustor Model Interface (CMI) developed at the University of Leeds. The CMI allows for the addition of dilution air at each stage of the combustor as well as re-circulation between each stage. The results at the combustor exit were then used as initial boundary conditions for the HES model, which followed the evolution of reacting gases through each of the pressure stages of the HES. This combination of the two models allowed the chemistry occurring throughout an engine, from combustor inlet to turbine exit, to be simulated. The principal aim of this modelling programme was to determine the extent of conversion of the sulphur (IV) species, SO2, to the sulphur (VI) species, SO3 and H2SO4. The predicted level of this conversion at the exit of the HES was found to be in very good agreement with the experimentally measured values. These values were lower than had been previously determined by modelling studies and this was found to result from changes made to the thermodynamic properties of the key intermediate, HOSO2, following recent experimental measurements. The results also showed that for these tests, the predominant sulphur conversion process occurred within the combustor itself rather than the turbine or beyond.

scholarly journals Performance evaluation of the Q.Clear reconstruction framework versus conventional reconstruction algorithms for quantitative brain PET-MR studies

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Daniela Ribeiro ◽  
William Hallett ◽  
Adriana A. S. Tavares
Keyword(s):  
Kinetic Modelling ◽  
Signal To Noise Ratio ◽  
Reconstruction Algorithm ◽  
Reconstruction Algorithms ◽  
Brain Pet ◽  
Good Spatial Resolution ◽  
Positron Emission ◽  
Pet Ct ◽  
Modelling Studies ◽  
Pet Scans

Abstract Background Q.Clear is a Bayesian penalized likelihood (BPL) reconstruction algorithm that presents improvements in signal-to-noise ratio (SNR) in clinical positron emission tomography (PET) scans. Brain studies in research require a reconstruction that provides a good spatial resolution and accentuates contrast features however, filtered back-projection (FBP) reconstruction is not available on GE SIGNA PET-Magnetic Resonance (PET-MR) and studies have been reconstructed with an ordered subset expectation maximization (OSEM) algorithm. This study aims to propose a strategy to approximate brain PET quantitative outcomes obtained from images reconstructed with Q.Clear versus traditional FBP and OSEM. Methods Contrast recovery and background variability were investigated with the National Electrical Manufacturers Association (NEMA) Image Quality (IQ) phantom. Resolution, axial uniformity and SNR were investigated using the Hoffman phantom. Both phantoms were scanned on a Siemens Biograph 6 TruePoint PET-Computed Tomography (CT) and a General Electric SIGNA PET-MR, for FBP, OSEM and Q.Clear. Differences between the metrics obtained with Q.Clear with different β values and FBP obtained on the PET-CT were determined. Results For in plane and axial resolution, Q.Clear with low β values presented the best results, whereas for SNR Q.Clear with higher β gave the best results. The uniformity results are greatly impacted by the β value, where β < 600 can yield worse uniformity results compared with the FBP reconstruction. Conclusion This study shows that Q.Clear improves contrast recovery and provides better resolution and SNR, in comparison to OSEM, on the PET-MR. When using low β values, Q.Clear can provide similar results to the ones obtained with traditional FBP reconstruction, suggesting it can be used for quantitative brain PET kinetic modelling studies.

scholarly journals Modelling the removal of Lead from synthetic contaminated water by activated carbon from biomass of Diplocyclos Palmatus by RSM

2019 ◽  
Keyword(s):  
Activated Carbon ◽  
Kinetic Modelling ◽  
Xrd Analysis ◽  
Synthetic Wastewater ◽  
Effect Of Temperature ◽  
Modelling Studies ◽  
Langmuir Isotherm Model ◽  
Pseudo Second Order ◽  
Ft Ir ◽  
Structural Surface

<p>Diplocyclos Palmatus biomass activated carbon (DPAC) was used in this work to remove lead (II) ion from the synthetic wastewater. The DPAC was characterized for structural, surface morphology by SEM, functional group was analyzed by FT-IR and XRD analysis. Removal of Pb2+ was studied by batch method and various experimental parameters namely effect of Pb2+ concentration, contact time, effect of temperature; pH and effect of matrix were also studied. Kinetic modelling studies showed that the adsorption of Pb2+ ion follows pseudo second order mechanism and Langmuir isotherm model was found to fit better for this study. Thermodynamic study shows a negative value for ΔG indicating the process is spontaneous. Box Behnken Design using response surface methodology as DOE was carried out in this work. RSM modelling was found to be successful in predicting the removal efficiency with R2 greater than 0.95.</p>

scholarly journals Reaction of protein chloramines with DNA and nucleosides: evidence for the formation of radicals, protein–DNA cross-links and DNA fragmentation

2002 ◽  
Vol 365 (3) ◽  
pp. 605-615 ◽  
Author(s):  
Clare L. HAWKINS ◽  
David I. PATTISON ◽  
Michael J. DAVIES
Keyword(s):  
Kinetic Modelling ◽  
Eukaryotic Cell ◽  
Water Soluble ◽  
Cell Nuclei ◽  
Strand Breaks ◽  
Modelling Studies ◽  
Cross Links ◽  
Protein Radicals ◽  
Epr Experiments

Stimulated phagocyte cells produce the oxidant HOCl, via the release of the enzyme myeloperoxidase and hydrogen peroxide. HOCl is important in bacterial cell killing, but excessive or misplaced generation can damage the host tissue and may lead to the development of certain diseases such as cancer. The role of HOCl in the oxidation of isolated proteins, DNA and their components has been investigated extensively, but little work has been performed on the protein—DNA (nucleosome) complexes present in eukaryotic cell nuclei. Neither the selectivity of damage in such complexes nor the possibility of transfer of damage from the protein to DNA or vice versa, has been studied. In the present study, kinetic modelling has been employed to predict that reaction occurs predominantly with the protein and not with the DNA in the nucleosome, using molar HOCl excesses of up to 200-fold. With 50–200-fold excesses, 50–80% of the HOCl is predicted to react with histone lysine and histidine residues to yield chloramines. The yield and stability of such chloramines predicted by these modelling studies agrees well with experimental data. Decomposition of these species gives protein-derived, nitrogen-centred radicals, probably on the lysine side chains, as characterized by the EPR and spin-trapping experi ments. It is shown that isolated lysine, histidine, peptide and protein chloramines can react with plasmid DNA to cause strand breaks. The protection against such damage afforded by the radical scavengers Trolox (a water-soluble α-tocopherol derivative) and 5,5-dimethyl-1-pyrroline-N-oxide suggests a radical-mediated process. The EPR experiments and product analyses have also provided evidence for the rapid addition of protein radicals, formed on chloramine decomposition, to pyrimidine nucleosides to give nucleobase radicals. Further evidence for the formation of such covalent cross-links has been obtained from experiments performed using 3H-lysine and 14C-histidine chloramines. These results are consistent with the predictions of the kinetic model and suggest that histones are major targets for HOCl in the nucleosome. Furthermore, the resulting protein chloramines and the radicals derived from them may act as contributing agents in HOCl-mediated DNA oxidation.

Experimental and kinetic modelling studies on the acid-catalysed hydrolysis of the water hyacinth plant to levulinic acid

2008 ◽  
Vol 99 (17) ◽  
pp. 8367-8375 ◽  
Author(s):  
B. Girisuta ◽  
B. Danon ◽  
R. Manurung ◽  
L.P.B.M. Janssen ◽  
H.J. Heeres
Keyword(s):  
Water Hyacinth ◽  
Levulinic Acid ◽  
Kinetic Modelling ◽  
Modelling Studies ◽  
Hydrolysis Of

Kinetic modelling studies of amine–epoxide reactions: application of radiochemical and numerical techniques

1995 ◽  
Vol 5 (2) ◽  
pp. 213-217 ◽  
Author(s):  
Gabriel J. Buist ◽  
John M. Barton ◽  
Brendan J. Howlin ◽  
John R. Jones ◽  
Mark J. Parker
Keyword(s):  
Kinetic Modelling ◽  
Numerical Techniques ◽  
Modelling Studies
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