SEARCH · Engineering Papers
Results for “C”
Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
First observation of the decay χ c J → Σ + p ¯ K S 0 + c . c . ( J = 0 , 1 , 2 )
Not Available
Search for the rare decay of ψ ( 3686 ) → Λ c + p ¯ e + e − + c . c . at BESIII
Not Available
Search for baryon and lepton number violation in J / ψ → Λ c + e − + c . c .
Not Available
Implications for Extraterrestrial Hydrocarbon Chemistry: Analysis of Ethylene (C{sub 2}H{sub 4}) and D4-Ethylene (C{sub 2}D{sub 4}) Ices Exposed to Ionizing Radiation via Combined Infrared Spectroscopy and Reflectron Time-of-flight Mass Spectrometry
The processing of the hydrocarbon ice, ethylene (C{sub 2}H{sub 4}/C{sub 2}D{sub 4}), via energetic electrons, thus simulating the processes in the track of galactic cosmic-ray particles, was carried out in an ultrahigh vacuum apparatus. The chemical evolution of the ices was monitored online and in situ utilizing Fourier transform infrared spectroscopy (FTIR) and during temperature programmed desorption, via a quadrupole mass spectrometer utilizing electron impact ionization (EI-QMS) and a reflectron time-of-flight mass spectrometer utilizing a photoionization source (PI-ReTOF-MS). Several previous in situ studies of ethylene ice irradiation using FTIR were substantiated with the detection of six products: [CH{sub 4} (CD{sub 4})], acetylene [C{sub 2}H{sub 2} (C{sub 2}D{sub 2})], the ethyl radical [C{sub 2}H{sub 5} (C{sub 2}D{sub 5})], ethane [C{sub 2}H{sub 6} (C{sub 2}D{sub 6})], 1-butene [C{sub 4}H{sub 8} (C{sub 4}D{sub 8})], and n -butane [C{sub 4}H{sub 10} (C{sub 4}D{sub 10})]. Contrary to previous gas phase studies, the PI-ReTOF-MS detected several groups of hydrocarbon with varying degrees of saturation: C{sub n}H{sub 2n+2} (n = 4–10), C{sub n}H{sub 2n} ( n = 2–12, 14, 16), C{sub n}H{sub 2n−2} ( n = 3–12, 14, 16), C{sub n}H{sub 2n−4} (n = 4–12, 14, 16), C{sub n}H{sub 2n−6} (n = 4–10, 12), C{sub n}H{sub 2n−8} ( n = 6–10), and C{sub n}H{sub 2n−10} ( n = 6–10). Multiple laboratory studies have shown the facile production of ethylene from methane, which is a known ice constituent in the interstellar medium. Various astrophysically interesting molecules can be associated with the groups detected here, such as allene/methylacetylene (C{sub 3}H{sub 4}) or 1, 3-butadiene (C{sub 4}H{sub 6}) and its isomers, which have been shown to lead to polycyclic aromatic hydrocarbons. Finally, several hydrocarbon groups detected here are unique to ethylene ice versus ethane ice and may provide understanding of how complex hydrocarbons form in astrophysical environments.
Cytochrome c{sub 6B} of Synechococcus sp. WH 8102 – Crystal structure and basic properties of novel c{sub 6}-like family representative
Highlights: • Crystal structure of cytochrome c{sub 6B} from Synechococcus sp. WH 8102 was solved. • Basic biophysical properties of cytochrome c{sub 6B} were determined. • Cytochrome c{sub 6B} exhibits similar architecture to cytochrome c{sub 6}. • Organization of heme binding pocket of cytochrome c{sub 6B} differs from that of c{sub 6}. • Midpoint potential of cytochrome c{sub 6B} is significantly lower than of cytochrome c{sub 6}. - Abstract: Cytochromes c are soluble electron carriers of relatively low molecular weight, containing single heme moiety. In cyanobacteria cytochrome c{sub 6} participates in electron transfer from cytochrome b{sub 6}f complex to photosystem I. Recent phylogenetic analysis revealed the existence of a few families of proteins homologous to the previously mentioned. Cytochrome c{sub 6A} from Arabidopsis thaliana was identified as a protein responsible for disulfide bond formation in response to intracellular redox state changes and c{sub 550} is well known element of photosystem II. However, function of cytochromes marked as c{sub 6B}, c{sub 6C} and c{sub M} as well as the physiological process in which they take a part still remain unidentified. Here we present the first structural and biophysical analysis of cytochrome from the c{sub 6B} family from mesophilic cyanobacteria Synechococcus sp. WH 8102. Purified protein was crystallized and its structure was refined at 1.4 Å resolution. Overall architecture of this polypeptide resembles typical I-class cytochromes c. The main features, that distinguish described protein from cytochrome c{sub 6}, are slightly red-shifted α band of UV–Vis spectrum as well as relatively low midpoint potential (113.2 ± 2.2 mV). Although, physiological function of cytochrome c{sub 6B} has yet to be determined its properties probably exclude the participation of this protein in electron trafficking between b{sub 6}f complex and photosystem I.
Study of the B - → Λ c + Λ ¯ c - K - decay
The decay B - → $Λ^+_c \overline{Λ}^-_c K^-$ is studied in proton-proton collisions at a center-of-mass energy of $\sqrt{s}$ = 13 TeV using data corresponding to an integrated luminosity of 5 fb -1 collected by the LHCb experiment. In the $Λ^+_c K^-$ system, the Ξ c (2930) 0 state observed at the BABAR and Belle experiments is resolved into two narrower states, Ξ c (2923) 0 and Ξ c (2939) 0 , whose masses and widths are measured to be m(Ξ c (2923) 0 ) = 2924.5 ± 0.4 ± 1.1 MeV, m(Ξ c (2939) 0 ) = 2938.5 ± 0.9 ± 2.3 MeV, Γ(Ξ c (2923) 0 ) = 4.8 ± 0.9 ± 1.5 MeV, Γ(Ξ c (2939) 0 ) = 11.0 ± 1.9 ± 7.5 MeV, where the first uncertainties are statistical and the second systematic. The results are consistent with a previous LHCb measurement using a prompt $Λ^+_c K^-$ sample. Evidence of a new Ξ c (2880) 0 state is found with a local significance of 3.8σ, whose mass and width are measured to be 2881.8 ± 3.1 ± 8.5 MeV and 12.4 ± 5.3 ± 5.8 MeV, respectively. In addition, evidence of a new decay mode Ξ c (2790) 0 → $Λ^+_c K^-$ is found with a significance of 3.7σ. The relative branching fraction of B - → $Λ^+_c \overline{Λ}^-_c K^-$ with respect to the B - → D + D - K - decay is measured to be 2.36 ± 0.11 0.22 ± 0.25, where the first uncertainty is statistical, the second systematic and the third originates from the branching fractions of charm hadron decays.
Search for η c ( 2 S ) → ω ω and ω ϕ and measurements of χ c J → ω ω and ω ϕ in ψ ( 2 S ) radiative processes
Using ( 2712 ± 14 ) × 10 6 ψ ( 2 S ) events collected with the BESIII detector at the BEPCII collider, we search for the decays η c ( 2 S ) → ω ω and η c ( 2 S ) → ω ϕ via the process ψ ( 2 S ) → γ η c ( 2 S ) . No statistically significant signals are observed. The upper limits of their product branching fractions at the 90% confidence level are determined to be B ( ψ ( 2 S ) → γ η c ( 2 S ) , η c ( 2 S ) → ω ω ) < 1.04 × 10 − 6 and B ( ψ ( 2 S ) → γ η c ( 2 S ) , η c ( 2 S ) → ω ϕ ) < 1.85 × 10 − 7 , respectively. We also update the branching fractions of χ c J → ω ω and χ c J → ω ϕ via the ψ ( 2 S ) → γ χ c J transition. Their branching fractions are determined to be B ( χ c 0 → ω ω ) = ( 10.66 ± 0.11 ± 0.57 ) × 10 − 4 , B ( χ c 1 → ω ω ) = ( 6.43 ± 0.07 ± 0.31 ) × 10 − 4 , B ( χ c 2 → ω ω ) = ( 8.75 ± 0.08 ± 0.42 ) × 10 − 4 , B ( χ c 0 → ω ϕ ) = ( 1.18 ± 0.03 ± 0.07 ) × 10 − 4 , B ( χ c 1 → ω ϕ ) = ( 2.04 ± 0.15 ± 0.11 ) × 10 − 5 , and B ( χ c 2 → ω ϕ ) = ( 9.58 ± 1.07 ± 0.76 ) × 10 − 6 , where the first uncertainties are statistical and the second are systematic. Published by the American Physical Society 2025
Simultaneous Activation of CH4 and CO2 for Concerted C-C Coupling at the Oxide-Oxide Interfaces
Catalytic conversion of CO2 and CH4 to value-added platform chemicals via the direct C-C coupling provides one of the most effective routes that not only address global climate change but also alleviate the dependency on traditional fossil fuels. Herein, three oxide-on-oxide catalysts that can realize direct C-C coupling on the basis of simultaneous activation of CH4 and CO2 were investigated using density functional theory (DFT) calculations. With the formation of oxide-on-oxide interfacial sites between the substrate (In2O3) and dispersed oxides ((ZnO)3, (ZrO2)3, or Ga2O3), it is found that CO2 can be activated at the defective site of In2O3 while the C-H bond of CH4 can be simultaneously activated at the M-O pair of the supported metal oxide. In contrast to the Eley-Rideal mechanism that C-C coupling of CO2 and CH3 stabilized on Zn-doped ceria follows, the formation of a Zn-C-C-O transition state at the active centers originates from a Langmuir-Hinshelwood mechanism where the activated CO2 also enhances the dissociative adsorption of CH4. There is a linear relationship between the C-C coupling reaction energy/activation barrier and CH4 dissociation energy. The results indicate that dissociative adsorption of CH4 plays a dominant role in the direct C-C coupling, whereas the adsorption/activation of CO2 is less significant. DFT calculation results of CH4 and CO2 to acetic acid on the (ZnO)3/In2O3 catalyst surface indicates that the C-C coupling step is the kinetically most relevant step. Compared with Ga2O3/In2O3 and (ZrO2)3/In2O3 catalyst surfaces, (ZnO)3/In2O3(110) is more active for the acetic acid formation. The present work provides new mechanistic insights into the direct C-C coupling of CH4 and CO2, which would be useful to design more efficient catalyst.
Impacts of 1.5 °C and 2.0 °C global warming above pre-industrial on potential winter wheat production of China
Keeping global temperatures below 2.0 °C above pre-industrial condition and pursuing efforts toward the more ambitious 1.5 °C goal in the late 21st century was the main target from the Paris Agreement in 2015. Here we assessed the likely challenges for the China’s winter wheat production under 1.5 °C and 2.0 °C increase of global temperature, with four wheat crop models (CERES-Wheat, Nwheat, WheatGrow, and APSIM-Wheat) and the latest climate projections from the Half a degree Additional warming, Prognosis and Projected Impacts project (HAPPI). Instead of using average “winter type” wheat cultivar, and same management and soil inputs for whole region, location-specific winter wheat cultivars with local agronomic information were calibrated for each of the representative wheat growing area of China, allowing a better spatial agronomic representation of the whole wheat planting area. The mean growing season temperature (GST) during the winter wheat vegetative stage was projected to increase by 0.6 to 1.4 °C for the 1.5 °C scenario, and 0.9 to 1.8 °C for the 2.0 °C scenario, while during the reproductive stage was decreased between 0 and 0.9 °C for the 1.5 °C scenario and -0.3 and 1.1 °C for the 2.0 °C scenario. Growing season duration (GSD) for the whole period was shortened by 6 to 15 days for the 1.5 °C scenario and 8 to 18 days for the 2.0 °C scenario, as a result of higher GST under global warming. Increase in GST and decrease in GSD was more obvious in the Southwest Subregion (SWS) than subregions in the north. The shortening GSD for the whole wheat growth period was mostly from the shortening vegetative period, as no appreciable difference in number of days from anthesis to maturity was found for the whole regions. Although there is variability among models, the indication is that wheat yields were projected to increase in the North Subregion (NS), the Huang-Huai Subregion (HHS), and the Middle-lower Researches of Yangzi River Subregion (MYS), but to decrease in the SWS under two warming scenarios. The effects of elevated CO2 concentration were mostly beneficial and tended to offset the negative impacts of increasing temperature at both global warming scenarios, with a rate of 7-14% yield increase per 100-ppm, except for locations with GST of baseline higher than 11 °C. Aggregating to regional wheat production, the total winter wheat production of China was projected to increase by 2.8% (1.6% to 3.0%, 25th percentile to 75th percentile) and 8.3% (7.0% to 9.6%, 25th percentile to 75th percentile) under 1.5 °C and 2.0 °C scenarios, and most of increase was observed in the north subregions due to the largest wheat planting area. Our results will lay the foundation for developing adaptation strategies to future climate change to ensure China and global wheat supply and food security.
Λ c + production in Pb–Pb collisions at s NN = 5.02 TeV
A measurement of the production of prompt $\Lambda^+_c$ baryons in Pb–Pb collisions at $\sqrt{s_{NN}} = 5.02$ TeV with the ALICE detector at the LHC is reported. The $\Lambda^+_c$ and $\Lambda^-_c$ were reconstructed at midrapidity ($\mid{y}\mid < 0.5$) via the hadronic decay channel $\Lambda^+_c$ $\rightarrow {pK^0_s}$ (and charge conjugate) in the transverse momentum and centrality intervals GeV/c and 0–80%. The ratio, which is sensitive to the charm quark hadronisation mechanisms in the medium, is measured and found to be larger than the ratio measured in minimum-bias pp collisions at TeV and in p–Pb collisions at TeV. In particular, the values in p–Pb and Pb–Pb collisions differ by about two standard deviations of the combined statistical and systematic uncertainties in the common interval covered by the measurements in the two collision systems. The ratio is also compared with model calculations including different implementations of charm quark hadronisation. The measured ratio is reproduced by models implementing a pure coalescence scenario, while adding a fragmentation contribution leads to an underestimation. The nuclear modification factor, , is also presented. The measured values of the of , and non-strange D mesons are compatible within the combined statistical and systematic uncertainties. They show, however, a hint of a hierarchy , conceivable with a contribution from coalescence mechanisms to charm hadron formation in the medium.
The Atomic Structure of Ti{sub 2}C and Ti{sub 3}C{sub 2} MXenes is Responsible for Their Antibacterial Activity Toward E. coli Bacteria
The expanded Ti{sub 2}C and Ti{sub 3}C{sub 2} MXene phases were synthesized from their parent Ti{sub 2}AlC and Ti{sub 3}AlC{sub 2} MAX phases using the same conditions of the classical acidic aluminum extraction method. The assumption for the study was that the expanded Ti{sub 2}C and Ti{sub 3}C{sub 2} MXenes are composed of the same atoms and if are synthesized from MAX phases using the same conditions of the classical acidic aluminum extraction method, the observed bio-effects can be related only to the changes in their structures. The scanning electron microscope investigations indicated that the expanded Ti{sub 2}C and Ti{sub 3}C{sub 2} sheets formed the specific network of slit-shaped nano-pores. The x-ray photoelectron spectroscopy for chemical analysis (ESCA-XPS) showed almost no difference in surface chemistry of Ti{sub 2}C and Ti{sub 3}C{sub 2} MXenes. The high-resolution transmission electron microscope investigations revealed, however, differences in atomic structure of the individual Ti{sub 2}C and Ti{sub 3}C{sub 2} sheets. Measured distance between Ti-C atomic layers in Ti{sub 2}C was 9.76 Å and was larger by 0.53 Å in comparison with Ti{sub 3}C{sub 2} (9.23 Å). Our investigations of bioactive properties toward model gram-negative Escherichia coli bacterial strain showed that the Ti{sub 2}C MXene did not influence the viability of bacteria. Contrarily, the Ti{sub 3}C{sub 2} MXene showed antibacterial properties. The results of the study indicate that the structure at the atomic scale may play a key role in the bioactivity of MXenes of the same chemical composition, but different stoichiometry, just like in case of Ti{sub 2}C and Ti{sub 3}C{sub 2}.
Acetylene and Ethylene Adsorption on a β-Mo 2 C(100) Surface: A Periodic DFT Study on the Role of C- and Mo-Terminations for Bonding and Hydrogenation Reactions
Mo 2 C catalysts are widely used in hydrogenation reactions; however, the role of the C and Mo terminations in these catalysts is not clear. Understanding the binding of adsorbates is key for explaining the activity of Mo 2 C. The adsorption of acetylene and ethylene, probe molecules representing alkynes and olefins, respectively, was studied in this paper on a β-Mo 2 C(100) surface with C and Mo terminations using calculations based on periodic density functional theory. Moreover, the role of the C/Mo molar ratio was investigated to compare the catalytic potential of cubic (δ-MoC) and orthorhombic (β-Mo 2 C) surfaces. The geometry and electronic properties of the clean δ-MoC(001) and β-Mo 2 C(100) surfaces have a strong influence on the binding of unsaturated hydrocarbons. The adsorption of ethylene is weaker than that of acetylene on the surfaces of the cubic and orthorhombic systems; adsorption of the hydrocarbons was stronger on β-Mo 2 C(100) than on δ-MoC(001). The C termination in β-Mo 2 C(100) actively participates in both acetylene and ethylene adsorption and is not merely a spectator. Finally, the results of this work suggest that the β-Mo 2 C(100)-C surface could be the one responsible for the catalytic activity during the hydrogenation of unsaturated C≡C and C=C bonds, while the Mo-terminated surface could be poisoned or transformed by the strong adsorption of C and CH x fragments.
Enhanced Selectivity for C 2 H 4 Production from C 2 H 6 on Partially Chlorinated IrO 2 (110) Surfaces
Modifying metal oxide surfaces to limit their oxidizing activity can provide a means of improving catalytic selectivity toward the partial oxidation of light alkanes. Here, in this study, we investigated the oxidation of C 2 H 6 on Cl-modified IrO 2 (110) surfaces using temperature-programmed reaction spectroscopy (TPRS) and first-principles microkinetic modeling. We find that substituting Cl for O in the IrO 2 (110) surface enhances the selectivity for C 2 H 6 conversion to C 2 H 4 during TPRS by suppressing extensive oxidation to CO x products, while also either enhancing C 2 H 4 production or altering it to a lesser extent, depending on the initial C 2 H 6 coverage. The C 2 H 4 selectivity increased with increasing C 2 H 6 and Cl coverage, but reached a limiting value below 50%. The Cl coverage changed negligibly during C 2 H 6 oxidation, and the surface reactivity decreased only marginally for Cl coverages up to 0.5 ML (monolayer). TPRS simulations using a microkinetic model predict C 2 H 4 and CO x product yields as a function of the Cl coverage that agree closely with the experimental results. According to the simulations, C 2 H 6 conversion to C 2 H 4 occurs on Cl-IrO 2 (110) by the hydrogenation of C 2 H 3 * species adsorbed in blocked states, in which neighboring sites are occupied only by unreactive HO and Cl species. The microkinetic modeling shows that H-hopping away from surface HO groups provides a relatively efficient route for C 2 H 3 * to escape blocked configurations and dehydrogenate, and that this process can limit the C 2 H 4 selectivity on Cl-IrO 2 (110) under the conditions studied. Overall, our results demonstrate that Cl-substitution into IrO 2 (110) enhances the selectivity for C 2 H 4 production from C 2 H 6 and provides insights into the reaction mechanism that can guide strategies to further improve the C 2 H 4 selectivity.
USc 2 C 2 and USc 2 NC Clusters with U–C Triple Bond Character Stabilized Inside Fullerene Cages
The chemistry of f-block metal–carbon multiple bonds is underdeveloped compared to well-established carbene complexes of the d-block transition metals. Herein, we report two new actinide-rare earth mixed metal carbides and nitrogen carbide cluster fullerenes, USc 2 C 2 @D 5h (6)-C 80 and USc 2 NC@D 5h (6)-C 80 , which contain U–C bonds with triple bond character and were successfully synthesized and characterized by mass spectrometry, UV–vis–NIR spectroscopy, Fourier transform infrared spectroscopy, single crystal X-ray diffraction, and DFT calculations. Crystallographic studies show that the two previously unreported clusters, USc 2 C 2 and USc 2 NC, are stabilized in the D 5h (6)-C 80 carbon cage and adopt unique trifoliate configurations, in which C 2 /NC units are almost vertically inserted into the plane defined by the U and two Sc atoms. Combined experimental and theoretical studies further reveal the bonding structure of USc 2 C 2 and USc 2 NC, which contain C=U(VI)=C and C=U(V)=N bonding motifs. The electronic structures of the two compounds are determined as U 6+ (Sc 2 ) 6+ (C 4– ) 2 @D 5h (6)-C 80 4– and U 5+ (Sc 2 ) 6+ (N) 3– (C) 4– @D 5h (6)-C 80 4– , respectively. Quantum-chemical studies confirm that the U–C bonds in both molecules show unprecedented multicenter triple-bond character. Furthermore, the discovery of this unique U–C multiple bond offers a deeper understanding of the fundamentals of uranium chemistry.
Defect compensation by Cr vacancies and oxygen interstitials in T i 4 + -doped C r 2 O 3 epitaxial thin films
Not Available
Interaction of a pseudo-π C—C bond with cuprous and argentous chlorides: Cyclopropane⋯CuCl and cyclopropane⋯AgCl investigated by rotational spectroscopy and ab initio calculations
Strongly bound complexes (CH{sub 2}){sub 3}⋯MCl (M = Cu or Ag), formed by non-covalent interaction of cyclopropane and either cuprous chloride or argentous chloride, have been generated in the gas phase by means of the laser ablation of either copper or silver metal in the presence of supersonically expanded pulses of a gas mixture containing small amounts of cyclopropane and carbon tetrachloride in a large excess of argon. The rotational spectra of the complexes so formed were detected with a chirped-pulse, Fourier transform microwave spectrometer and analysed to give rotational constants and Cu and Cl nuclear quadrupole coupling constants for eight isotopologues of each of (CH{sub 2}){sub 3}⋯CuCl and (CH{sub 2}){sub 3}⋯AgCl. The geometry of each of these complexes was established unambiguously to have C{sub 2v} symmetry, with the three C atoms coplanar, and with the MCl molecule lying along a median of the cyclopropane C{sub 3} triangle. This median coincides with the principal inertia axis a in each of the two complexes (CH{sub 2}){sub 3}⋯MCl. The M atom interacts with the pseudo-π bond linking the pair of equivalent carbon atoms {sup F}C (F = front) nearest to it, so that M forms a non-covalent bond to one C—C edge of the cyclopropane molecule. The (CH{sub 2}){sub 3}⋯MCl complexes have similar angular geometries to those of the hydrogen- and halogen-bonded analogues (CH{sub 2}){sub 3}⋯HCl and (CH{sub 2}){sub 3}⋯ClF, respectively. Quantitative details of the geometries were determined by interpretation of the observed rotational constants and gave results in good agreement with those from ab initio calculations carried out at the CCSD(T)(F12*)/aug-cc-pVTZ-F12 level of theory. Interesting geometrical features are the lengthening of the {sup F}C—{sup F}C bond and the shrinkage of the two equivalent {sup B}C—{sup F}C (B = back) bonds relative to the C—C bond in cyclopropane itself. The expansions of the {sup F}C—{sup F}C bond are 0.1024(9) Å and 0.0727(17) Å in (CH{sub 2}){sub 3}⋯CuCl and (CH{sub 2}){sub 3}⋯AgCl, respectively, according to the determined r{sub 0} geometries. The C—C bond lengthening is in each case about four times that observed by similar methods in the corresponding complexes of MCl with ethyne and ethene, even though the cyclopropane complexes are more weakly bound than their ethyne and ethene analogues. Reasons for the larger increase in r(CC) in the pseudo-π complexes are discussed.
Scission of the Five-Membered Ring in 1- H -Inden-1-one C 9 H 6 O and Indenyl C 9 H 7 in the Reactions with H and O Atoms
Quantum chemical G3(MP2,CC)//B3LYP/6-311G(d,p) calculations of the C 9 H 7 O potential energy surface were utilized to investigate the mechanism of the 1-H-inden-1-one (C 9 H 6 O) + H and indenyl (C 9 H 7 ) + O reactions and were combined with Rice–Ramsperger–Kassel–Marcus Master Equation (RRKM-ME) calculations to predict temperature- and pressure-dependent reaction rate constants and product branching ratios. The most favorable reaction pathways for C 9 H 6 O + H lead to the bimolecular C 8 H 7 + CO products, which are slightly endothermic with respect to the reactants. The reaction begins with H addition to the ortho or meta C atoms in the five-membered ring, C 9 H 6 O + H → w2/w3, and then proceeds by isomerization to w1, (w3 →) w2 → w1. From thereon, the w1 → w9 → w8 → p1 and w2 → w8 → p1 pathways lead to ortho-vinyl phenyl + CO, whereas w1 → w10 → w11 → p2 and C 9 H 6 O + H → w10 → w11 → p2 produce styrenyl + CO. The results of the RRKM-ME calculations showed that only the well-skipping C 9 H 6 O + H → C 8 H 7 (p1/p2) + CO mechanism is relevant under combustion conditions. A comparison with a smaller prototype 2,4-cyclopentadienone + H → C 4 H 5 + CO reaction demonstrated that the H atom is a less efficient destroyer of a cyclopentadienone-like moiety when this moiety is linked to an aromatic or a PAH structure. The C 9 H 7 + O reaction begins with highly exothermic barrierless addition of the oxygen atom to the radical site in the five-membered ring of indenyl producing w1 and then, the reaction mostly proceeds by β-scission in the five-membered ring, which may be preceded by H migration to w2 or w10, and completes by the CO loss forming the highly exothermic C 8 H 7 radical products. Modified Arrhenius expressions for the rate constants of all reactions pertinent to the formation of C 8 H 7 + CO from C 9 H 6 O + H, C 9 H 7 + H, and unimolecular decomposition of benzopyranyl have been generated and suggested for combustion kinetic modeling. Furthermore, it is concluded that the oxidation reactions of a five-membered ring with atomic oxygen remain fast in the presence of attached or surrounding six-membered rings.