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A low-pressure premixed toluene/O 2 /Ar flame with the equivalence ratio of 1.90 was investigated using tunable synchrotron vacuum ultraviolet (VUV) photoionization mass spectrometry. Combustion intermediates up to C 19 H 12 were identified by the measurements of the photoionization mass spectrum and photoionization efficiency spectrum. Mole fraction profiles of flame species were evaluated from the scan of burner position at photon energies near ionization thresholds. Furthermore, flame temperature was recorded by a Pt/Pt-13%Rh thermocouple. The comprehensive experimental data concerning the flame structure facilitate the discussion about the flame chemistry of toluene and other monocyclic aromatic fuels. Benzyl and benzene were found to be major primary intermediates of toluene degradation; and benzene is suggested to originate mainly from fuel degradation instead of radical recombination channels in fuel-rich monocyclic aromatic hydrocarbon flames. On the basis of the intermediate identification, comparison is made among the current mechanisms relevant to the formation of polycyclic aromatic hydrocarbons (PAHs). It is concluded that the molecular growth process in this flame is consistent with the synergy of the hydrogen-abstraction-carbon-addition (HACA) mechanism and the resonantly stabilized radical addition mechanism. In particular, the HACA mechanism can connect a great deal of aromatic intermediates observed in the present work and consequently explain the regular ring enlargement by consecutive addition of 2 or 4 carbon atoms, while the resonantly stabilized radical addition mechanism may have marked and sometimes predominant influences on the formation of many typical PAHs.

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The detailed chemical structures of three low-pressure (35 Torr) premixed laminar furan/oxygen/ argon flames with equivalence ratios of 1.4, 1.8 and 2.2 have been investigated by using tunable synchrotron vacuum ultraviolet (VUV) photoionization and molecular-beam mass spectrometry. About 40 combustion species including hydrocarbons and oxygenated intermediates have been identified by measurements of photoionization efficiency spectra. Mole fraction profiles of the flame species including reactants, intermediates and products have been determined by scanning burner position with some selected photon energies near ionization thresholds. Flame temperatures have been measured by a Pt-6%Rh/Pt-30%Rh thermocouple. A new mechanism involving 206 species and 1368 reactions has been proposed whose predictions are in reasonable agreement with measured species profiles for the three investigated flames. Rate-of-production and sensitivity analyses have been performed to track the key reaction paths governing furan consumption for different equivalence ratios. Both experimental and modeling results indicate that few aromatics could be formed in these flames. Furthermore, the current model has been validated against previous pyrolysis results of the literature obtained behind shock waves and the agreement is reasonable as well.

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The conversion of life-threatening viruses into live but avirulent vaccines represents a revolution in vaccinology. In a proof-of-principle study, we expanded the genetic code of the genome of influenza A virus via a transgenic cell line containing orthogonal translation machinery. This generated premature termination codon (PTC)-harboring viruses that exerted full infectivity but were replication-incompetent in conventional cells. Genome-wide optimization of the sites for incorporation of multiple PTCs resulted in highly reproductive and genetically stable progeny viruses in transgenic cells. In mouse, ferret, and guinea pig models, vaccination with PTC viruses elicited robust humoral, mucosal, and T cell-mediated immunity against antigenically distinct influenza viruses and even neutralized existing infecting strains. The methods presented here may become a general approach for generating live virus vaccines that can be adapted to almost any virus.

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Tetragonal hausmannite (Mn 3 O 4 ) was synthesized by pulsed-spray evaporation chemical vapor deposition (PSE-CVD) at moderate temperatures. The thermal properties of the obtained Mn 3 O 4 thin films were evaluated with a newly developed in situ emission FTIR method. The performance of Mn 3 O 4 grown on flexible stainless steel mesh substrates was investigated toward the oxidation of CO and C 3 H 6 . X-ray diffraction (XRD) patterns, FTIR, and Raman spectroscopy reveal that only the single-phase tetragonal Mn 3 O 4 spinel structure was obtained within the temperature range of 350− 500 °C. The as-deposited Mn 3 O 4 is thermally stable up to 800 °C, and its reduction plays a determinant role in the catalytic process. Compared to conventional powder catalysts, the combination of PSE-CVD, in situ emission FTIR, and the flexible substrate provides a novel tool for catalyst synthesis and the evaluation of the thermal properties and catalytic performance.