The Experts below are selected from a list of 325248 Experts worldwide ranked by ideXlab platform
Matthias Ihme - One of the best experts on this subject based on the ideXlab platform.
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Fuel effects on lean blow out in a realistic gas turbine combustor
Combustion and Flame, 2017Co-Authors: Lucas Esclapez, Peter C, Eric K Mayhew, Rui Xu, Scott D Stouffer, Hai Wang, Matthias IhmeAbstract:Abstract Towards the implementation of alternative jet Fuels in aviation gas turbines, testing in combustor rigs and engines is required to evaluate the Fuel performance on combustion stability, relight, and lean blow-out (LBO) characteristics. The objective of this work is to evaluate the effect of different Fuel candidates on the operability of gas turbines by comparing a conventional Petroleum-Based Fuel with two other alternative Fuel candidates. A comparative study of Fuel properties is first conducted to identify physico-chemical processes that are affected by these Fuels. Subsequently, large-eddy simulations (LES) are performed to examine the performance of these Fuels on the stable condition close to blow-out in a referee gas turbine combustor. LES results are compared to available experimental data to assess their capabilities in reproducing observed Fuel effects. It is shown that the simulations correctly predict the spray main characteristics as well as the flame position. The change in OH*-emissions for different Fuel candidates is also qualitatively captured. An analysis of the flame anchoring mechanisms highlights the Fuel effects on the flame position. Finally, the LBO-behavior is examined in order to evaluate the LBO-limit in terms of equivalence ratio and identify Fuel effects on the blow-out behavior.
Christina M Payne - One of the best experts on this subject based on the ideXlab platform.
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inhibition mechanisms of rhodococcus erythropolis 2 hydroxybiphenyl 2 sulfinate desulfinase dszb
Journal of Physical Chemistry B, 2019Co-Authors: Landon C Mills, Derek L Englert, Christina M PayneAbstract:Naturally occurring enzymatic pathways enable highly specific, rapid thiophenic sulfur cleavage occurring at ambient temperature and pressure, which may be harnessed for the desulfurization of Petroleum-Based Fuel. One pathway found in bacteria is a four-step catabolic pathway (the 4S pathway) converting dibenzothiophene (DBT), a common crude oil contaminant, into 2-hydroxybiphenyl (HBP) without disrupting the carbon-carbon bonds. 2'-Hydroxybiphenyl-2-sulfinate desulfinase (DszB), the rate-limiting enzyme in the enzyme cascade, is capable of selectively cleaving carbon-sulfur bonds. Accordingly, understanding the molecular mechanisms of DszB activity may enable development of the cascade as industrial biotechnology. Based on crystallographic evidence, we hypothesized that DszB undergoes an active site conformational change associated with the catalytic mechanism. Moreover, we anticipated this conformational change is responsible, in part, for enhancing product inhibition. Rhodococcus erythropolis IGTS8 DszB was recombinantly produced and purified via Escherichia coli BL21 to test these hypotheses. Activity and the resulting conformational change of DszB in the presence of HBP were evaluated. The activity of recombinant DszB was comparable to the natively expressed enzyme and was inhibited via competitive binding of the product, HBP. Using circular dichroism, global changes in DszB conformation were monitored in response to HBP concentration, which indicated that both product and substrate produced similar structural changes. Molecular dynamics (MD) simulations and free energy perturbation with Hamiltonian replica exchange molecular dynamics (FEP/λ-REMD) calculations were used to investigate the molecular-level phenomena underlying the connection between conformation change and kinetic inhibition. In addition to the HBP, MD simulations of DszB bound to common, yet structurally diverse, crude oil contaminants 2',2-biphenol (BIPH), 1,8-naphthosultam (NTAM), 2-biphenyl carboxylic acid (BCA), and 1,8-naphthosultone (NAPO) were performed. Analysis of the simulation trajectories, including root-mean-square fluctuation (RMSF), center of mass (COM) distances, and strength of nonbonded interactions, when compared with FEP/λ-REMD calculations of ligand binding free energy, showed excellent agreement with experimentally determined inhibition constants. Together, the results show that the combination of a molecule's hydrophobicity and nonspecific interactions with nearby functional groups contributes to a competitive inhibition mechanism that locks DszB in a closed conformation and precludes substrate access to the active site.
Jiaping Zhao - One of the best experts on this subject based on the ideXlab platform.
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thermochemical conversion of triglycerides for production of drop in liquid Fuels
Renewable & Sustainable Energy Reviews, 2016Co-Authors: Junming Xu, Jianchun Jiang, Jiaping ZhaoAbstract:The increasing demand for transportation Fuels, coupled with the depletion of petroleum resources and growing environmental concerns necessitates the development of efficient conversion technologies for the production of bioFuels. Thermochemical approaches hold great promise for converting biomass into liquid Fuels in one step using heat and catalysis. Several thermochemical processes are employed in the production of liquid bioFuels depending on the target product properties: 1) direct thermal conversion; 2) catalytic cracking; 3) hydrodeoxygenation of plant oils and animal fats. Since enormous quantities of liquid Fuels are consumed by transport vehicles, converting biomass into drop-in liquid Fuels may reduce the dependence of the Fuel market on Petroleum-Based Fuel products. In this review, we summarize recent progress in technologies for large-scale direct thermochemical production of drop-in bioFuels. We focus on the technical aspects critical to commercialization of the technologies for production of drop-in Fuels from triglycerides, including cracking catalysts, catalytic cracking mechanisms, catalytic reactors, and bioFuel properties. We also discuss future prospects for direct thermochemical conversion in biorefineries for the production of high grade bioFuels.
Stacy K Seeley - One of the best experts on this subject based on the ideXlab platform.
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stationary phase selection and comprehensive two dimensional gas chromatographic analysis of trace biodiesel in petroleum based Fuel
Journal of Chromatography A, 2012Co-Authors: John V Seeley, Carly T Bates, James D Mccurry, Stacy K SeeleyAbstract:Abstract The GC × GC solvation parameter model has been used to identify effective stationary phases for the separation of fatty acid methyl esters (FAMEs) from petroleum hydrocarbons. This simple mathematical model was used to screen the 1225 different combinations of 50 stationary phases. The most promising pairs combined a poly(methyltrifluoropropylsiloxane) stationary phase with a poly(dimethyldiphenylsiloxane) stationary phase. The theoretical results were experimentally tested by equipping a GC × GC instrument with a DB-210 primary stationary phase and an HP-50+ secondary stationary phase. This instrument was used to analyze trace levels of FAMEs in kerosene. The FAMEs were fully separated from the petroleum hydrocarbons on the secondary dimension of the 2-D chromatogram. The resulting GC × GC method was shown to be capable of accurately quantifying FAME levels as low as 2 ppm (w/w). These results demonstrate the utility of the solvation parameter model for identifying optimal stationary phases for high resolution GC × GC separations. Furthermore, this work presents an effective method for determining the level of biodiesel contamination in aviation Fuel and other Petroleum-Based Fuels.
Landon C Mills - One of the best experts on this subject based on the ideXlab platform.
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inhibition mechanisms of rhodococcus erythropolis 2 hydroxybiphenyl 2 sulfinate desulfinase dszb
Journal of Physical Chemistry B, 2019Co-Authors: Landon C Mills, Derek L Englert, Christina M PayneAbstract:Naturally occurring enzymatic pathways enable highly specific, rapid thiophenic sulfur cleavage occurring at ambient temperature and pressure, which may be harnessed for the desulfurization of Petroleum-Based Fuel. One pathway found in bacteria is a four-step catabolic pathway (the 4S pathway) converting dibenzothiophene (DBT), a common crude oil contaminant, into 2-hydroxybiphenyl (HBP) without disrupting the carbon-carbon bonds. 2'-Hydroxybiphenyl-2-sulfinate desulfinase (DszB), the rate-limiting enzyme in the enzyme cascade, is capable of selectively cleaving carbon-sulfur bonds. Accordingly, understanding the molecular mechanisms of DszB activity may enable development of the cascade as industrial biotechnology. Based on crystallographic evidence, we hypothesized that DszB undergoes an active site conformational change associated with the catalytic mechanism. Moreover, we anticipated this conformational change is responsible, in part, for enhancing product inhibition. Rhodococcus erythropolis IGTS8 DszB was recombinantly produced and purified via Escherichia coli BL21 to test these hypotheses. Activity and the resulting conformational change of DszB in the presence of HBP were evaluated. The activity of recombinant DszB was comparable to the natively expressed enzyme and was inhibited via competitive binding of the product, HBP. Using circular dichroism, global changes in DszB conformation were monitored in response to HBP concentration, which indicated that both product and substrate produced similar structural changes. Molecular dynamics (MD) simulations and free energy perturbation with Hamiltonian replica exchange molecular dynamics (FEP/λ-REMD) calculations were used to investigate the molecular-level phenomena underlying the connection between conformation change and kinetic inhibition. In addition to the HBP, MD simulations of DszB bound to common, yet structurally diverse, crude oil contaminants 2',2-biphenol (BIPH), 1,8-naphthosultam (NTAM), 2-biphenyl carboxylic acid (BCA), and 1,8-naphthosultone (NAPO) were performed. Analysis of the simulation trajectories, including root-mean-square fluctuation (RMSF), center of mass (COM) distances, and strength of nonbonded interactions, when compared with FEP/λ-REMD calculations of ligand binding free energy, showed excellent agreement with experimentally determined inhibition constants. Together, the results show that the combination of a molecule's hydrophobicity and nonspecific interactions with nearby functional groups contributes to a competitive inhibition mechanism that locks DszB in a closed conformation and precludes substrate access to the active site.