Vol 1, No 2





Table of Contents

Articles

by Habib Boughzala, Marwen Chouri
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The title compound Bis(1,4-diazabicyclo[2.2.2]octane)octachlorido-di-bismuthate (III) dihydrate was obtained by slow evaporation at room temperature of a hydrochloric aqueous solution (pH=1) containing bismuth (III) nitrate and the 1,4-diazabicyclo[2.2.2]octane (DABCO) in a 1:2 molar ratio. This material crystallizes in the P21/c monoclinic space group with a=7.875(1)Å, b=18.380(2)Å, c=10.445(2)Å, β=105.95(1)° and Z=2.

The structure exhibits a zero-dimensional (0D) periodic arrangement of bioctahedra (Bi2Cl10)4- surrounded by organic cations 1,4-diazabicyclo[2.2.2]octane (DABCO). The crystal cohesion is achieved by N-H…Cl, N-H…O and O-H…Cl hydrogen interaction linking the different parts of the structure. This compound was characterized by different techniques such as IR, DSC, TGA-DTA, XRD, XPRD and photoluminescence (PL) at room temperature.

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Articles

by Yingjia Zhang
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Gas-phase auto-ignition delay times of methane/‘air’ (21% O2/79% Ar) mixtures were measured behind reflected shock waves, using a kinetic shock tube. Experiments were performed at fixed pressure of 1.8 MPa and at equivalence ratios of 0.5 and 1.0, over the temperature range of 800 – 1000 K. Overall, the effect of equivalence ratio on ignition delay time is negligible at entire temperatures measured in this study. Difference from traditional ignition regime of diluted methane mixtures at high temperatures, the undiluted methane/air mixtures presents a four-stage ignition process at low temperatures, namely deflagration delay, deflagration, transition of deflagration to detonation and detonation. Four popular kinetic mechanism, UBC Mech 2.1, GRI Mech 3.0, Aramco Mech 2.0 and USC Mech 2.0, were used to simulate the new data. Only UBC Mech 2.1 showed satisfactory predictions in the reactivity of undiluted methane mixtures, it was thus adopted to implement sensitivity analysis for identifying dominant reactions in the ignition process. Difference in channels contributing ȮH radicals causes a reduced global activation energy with decreasing temperatures.

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