A Reduced Chemical Kinetic Mechanism for Toluene Reference Fuels Based On DRGEP and QSSA Methods

As a gasoline surrogate fuel, the physical and chemical properties of toluene reference fuel (TRF) are relatively simple and stable, and the TRF chemical kinetic mechanism may be used in simulating combustion processes of gasoline. However, simulations using detailed or semi-detailed mechanisms have been limited due to the computational complexity and long computational time. For the construction of the reduced mechanism, the directed relation graph with error propagation (DRGEP) method is used to wipe out insignificant components efficiently, followed by the use of the quasi-steady state assumption (QSSA) method to separate quasi-steady-state (QSS) species from the kinetic ODEs. In addition, some elementary reactions involving the formation and destruction of H and phenyl methyl radicals are subjected to sensitivity analysis and some kinetic parameters of the relevant elementary reactions are revised. As a result, a reduced mechanism involving 234 reactions and 60 species is developed. Comparing the experimental records with the analog data by utilizing the reduced mechanism, good agreement can be obtained when ignition delay time (τ), laminar flame speed (SL) and molar fraction of vital species are measured. Moreover, the mechanism may predict SL more accurately under lean mixture (equivalence ratio φ < 1.0) conditions. The reduced mechanism is small and reliable in performance, which can commendably reproduce the combustion characteristics of gasoline surrogate

Transcriptome and expression profiling analysis revealed changes of multiple signaling pathways involved in immunity in the large yellow croaker during Aeromonas hydrophila infection

<p>Abstract</p> <p>Background</p> <p>The large yellow croaker (<it>Pseudosciaena crocea</it>) is an economically important marine fish in China suffering from severe outbreaks of infectious disease caused by marine bacteria such as <it>Aeromonas hydrophila </it>(<it>A. hydrophila</it>), resulting in great economic losses. However, the mechanisms involved in the immune response of this fish to bacterial infection are not fully understood. To understand the molecular mechanisms underlying the immune response to such pathogenic bacteria, we used high-throughput deep sequencing technology to investigate the transcriptome and comparative expression profiles of the large yellow croaker infected with <it>A. hydrophila</it>.</p> <p>Results</p> <p>A total of 13,611,340 reads were obtained and assembled into 26,313 scaffolds in transcriptional responses of the <it>A. hydrophila</it>-infected large yellow croaker. Via annotation to the NCBI database, we obtained 8216 identified unigenes. In total, 5590 (68%) unigenes were classified into Gene Ontology, and 3094 unigenes were found in 20 KEGG categories. These genes included representatives from almost all functional categories. By using Solexa/Illumina's DeepSAGE, 1996 differentially expressed genes (P value < 0.05) were detected in comparative analysis of the expression profiles between <it>A. hydrophila</it>-infected fish and control fish, including 727 remarkably upregulated genes and 489 remarkably downregulated genes. Dramatic differences were observed in genes involved in the inflammatory response. Bacterial infection affected the gene expression of many components of signaling cascades, including the Toll-like receptor, JAK-STAT, and MAPK pathways. Genes encoding factors involved in T cell receptor (TCR) signaling were also revealed to be regulated by infection in these fish.</p> <p>Conclusion</p> <p>Based on our results, we conclude that the inflammatory response may play an important role in the early stages of infection. The signaling cascades such as the Toll-like receptor, JAK-STAT, and MAPK pathways are regulated by <it>A. hydrophila </it>infection. Interestingly, genes encoding factors involved in TCR signaling were revealed to be downregulated by infection, indicating that TCR signaling was suppressed at this early period. These results revealed changes of multiple signaling pathways involved in immunity during <it>A. hydrophila </it>infection, which will facilitate our comprehensive understanding of the mechanisms involved in the immune response to bacterial infection in the large yellow croaker.</p

Magnetostratigraphic dating of the Linyi Fauna and implications for sequencing the mammalian faunas on the Chinese Loess Plateau

The Chinese Loess Plateau (CLP) in North China is an important terrestrial archive that witnessed the environmental changes and mammal and early human evolution in Asia over the past 2.6 Ma. Establishing precise ages for the Pleistocene faunas on the CLP is critical for better understanding of these environmental, biological, and archaeological issues. Here we report a new magnetostratigraphic record that places age constraints on the Linyi Fauna on the southeastern CLP. Our investigated 170-m-thick Linyi section mainly consists of two portions: (1) an overlying eolian Quaternary loess-paleosol sequence and (2) underlying fluvial-lacustrine sand and silty clay. Paleomagnetic results suggest that the composite section records the Brunhes chron, Jaramillo and Olduvai subchrons, and successive reverse polarity portions of the intervening Matuyama chron. The Linyi Fauna is located between Jaramillo and Olduvai subchrons in the fluvial-lacustrine interval, with an estimated age of similar to 1.5-1.6 Ma. Combining previously dated faunas, we establish a Pleistocene magnetochronology spanning from 2.54 to 0.65 Ma for the faunas on the CLP