6 research outputs found
Shock Tube Investigation and Modeling of Dicyclopentadiene: Fundamental to Application
No full textDicyclopentadiene (DCPD), a homodimer of cyclopentadiene (C5H6) was chosen for the present study. DCPD can be obtained by dehydrogenation of JP-10 (jet propellant C10H16) which is currently used as aviation fuel. The combustion chemistry for JP-10 is well established. Very few studies are present in the literature on the thermal decomposition of dicyclopentadiene. Hence, to begin with, the thermal decomposition of DCPD was carried out in a single pulse shock tube. The shock tube is incorporated with the step size driver insert to correct the non-ideal pressure rise due to non-ideal effects. Hence it facilitates the near-ideal behavior behind the reflected shock wave region. The experiments were performed behind the reflected shock wave in the temperature range of 1250-1550 K and pressure range of 13-16 atm. Also, Ab-initio calculations were carried out to find the minimum energy pathway that can lead to the formation of observed products. Thereupon the detailed kinetic modeling was carried out to simulate the concentration profile of different observed products. Ab-initio calculations were carried for the dissociation reaction of dicyclopentadiene to cyclopentadiene conversion. Quantum theory of atoms in molecule (QTAIM) which is based upon electron density topology provides insight into the reaction. AIM analysis along the reaction coordinate was carried out which provides information about bond breaking and bond making phenomenon occurring during chemical transformation. In addition, AIM analysis was used to identify the various types of non-covalent interactions present in the structures along the reaction coordinate from reactant to product. Ignition delays were measured for DCPD using the modified chemical shock tube (CST3) to characterize it as a fuel. The measurement of ignition delay times were performed for three different equivalent ratios 0.5, 1, and 1.5. A comparison of ignition delay times between JP-10 and DCPD has been made. Furthermore, a detailed kinetic mechanism was developed for a better understanding. In addition, a comparison was made between the calculated and experimental observed ignition delay times
A hydroquinone-specific screening system for directed P450 evolution
Get PDFThe direct hydroxylation of benzene to hydroquinone (HQ) under mild reaction conditions is a challenging task for chemical catalysts. Cytochrome P450 (CYP) monooxygenases are known to catalyze the oxidation of a variety of aromatic compounds with atmospheric dioxygen. Protein engineering campaigns led to the identification of novel P450 variants, which yielded improvements in respect to activity, specificity, and stability. An effective screening strategy is crucial for the identification of improved enzymes with desired characteristics in large mutant libraries. Here, we report a first screening system designed for screening of P450 variants capable to produce hydroquinones. The hydroquinone quantification assay is based on the interaction of 4-nitrophenylacetonitrile (NpCN) with hydroquinones under alkaline conditions. In the 96-well plate format, a low detection limit (5 μM) and a broad linear detection range (5 to 250 μM) were obtained. The NpCN assay can be used for the quantification of dihydroxylated aromatic compounds such as hydroquinones, catechols, and benzoquinones. We chose the hydroxylation of pseudocumene by P450 BM3 as a target reaction and screened for improved trimethylhydroquinone (TMHQ) formation. The new P450 BM3 variant AW2 (R47Q, Y51F, I401M, A330P) was identified by screening a saturation mutagenesis library of amino acid position A330 with the NpCN assay. In summary, a 70-fold improved TMHQ formation was achieved with P450 BM3 AW2 when compared to the wild type (WT) and a 1.8-fold improved TMHQ formation compared to the recently reported P450 BM3 M3 (R47S, Y51W, A330F, I401M). © 2018, The Author(s)
Dynamics of chemical bond: general discussion
No full text[[sponsorship]]原子與分子科學研究所[[note]]已出版;[SCI];有審查制度;具代表性[[note]]http://gateway.isiknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=Drexel&SrcApp=hagerty_opac&KeyRecord=1359-6640&DestApp=JCR&RQ=IF_CAT_BOXPLO
Dynamics of chemical bond: general discussion
No full text[[sponsorship]]原子與分子科學研究所[[note]]已出版;有審查制度;具代表
