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961.
Thermal decomposition of RDX from reactive molecular dynamics 总被引:1,自引:0,他引:1
Strachan A Kober EM van Duin AC Oxgaard J Goddard WA 《The Journal of chemical physics》2005,122(5):54502
We use the recently developed reactive force field ReaxFF with molecular dynamics to study thermal induced chemistry in RDX [cyclic-[CH(2)N(NO(2))](3)] at various temperatures and densities. We find that the time evolution of the potential energy can be described reasonably well with a single exponential function from which we obtain an overall characteristic time of decomposition that increases with decreasing density and shows an Arrhenius temperature dependence. These characteristic timescales are in reasonable quantitative agreement with experimental measurements in a similar energetic material, HMX [cyclic-[CH(2)N(NO(2))](4)]. Our simulations show that the equilibrium population of CO and CO(2) (as well as their time evolution) depend strongly of density: at low density almost all carbon atoms form CO molecules; as the density increases larger aggregates of carbon appear leading to a C deficient gas phase and the appearance of CO(2) molecules. The equilibrium populations of N(2) and H(2)O are more insensitive with respect to density and form in the early stages of the decomposition process with similar timescales. 相似文献
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K. Pilch P. van Nieuwenhuizen M. F. Sohnius 《Communications in Mathematical Physics》1985,98(1):105-117
A general analysis of all possible super-extensions of anti-de Sitter and de Sitter algebrasO(3, 2) andO(4, 1) is presented. It is shown that actions with de Sitter local supersymmetry exist, but contain vector-ghosts.Supported in part by the NSF under grant PHY 81-09110 A-01On leave from the Institute of Theoretical Physics, University of Wrocaw, Wrocaw, Poland 相似文献
964.
Haas P Hempstead M Jensen T Kagan H Kass R Behrends S Gentile T Guida JM Guida JA Morrow F Poling R Rosenfeld C Thorndike EH Tipton P Besson D Green J Namjoshi R Sannes F Skubic P Stone R Bortoletto D Chen A Goldberg M Horwitz N Jawahery A Lubrano P Moneti GC Trahern CG van Hecke H Csorna SE Garren L Mestayer MD Panvini RS Word GB Yi X Alam MS Bean A Ferguson T Avery P Bebek C Berkelman K Blucher E Cassel DG Copie T DeSalvo R DeWire JW Ehrlich R Galik RS Gilchriese MG Gittelman B Gray SW 《Physical review letters》1985,55(12):1248-1251
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Elisângela Corradini Luís C. de Morais Nicole R. Demarquette José A. M. Agnelli Luiz H. C. Mattoso 《先进技术聚合物》2007,18(10):861-867
This work involved a study of the effect of processing variables (temperature, water content, rotor speed, and time) on the mechanical properties of starch:gluten:glycerol mixtures in the weight ratio of 40:40:20. The properties of the materials were affected by the processing variables. The torque decreased with water content, indicating that water facilitates the plasticization of mixtures, whereas the increase in temperature accelerated the evaporation of water, thus increasing the torque. Ultimate tensile strength was achieved at the lowest temperature (110°C) and the highest water content (20%), whereas maximum elongation was achieved for the material processed at the highest temperature, 150°C, and the fastest rotor speed, 70 rpm. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
970.
Chromatography has been an important tool in marine laboratories. Since the 1960s, marine laboratories have been involved in the analysis of polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs), polycyclic aromatic hydrocarbons (PAHs), and brominated flame retardants (BFRs). Column chromatography and liquid chromatography (LC) techniques have been used, mainly in the clean-up phase, while gas chromatography (GC) has been used extensively in the final determination of these contaminants. Developments have been observed from the use of packed GC columns, via capillary columns to the use of heart-cut multi-dimensional GC and comprehensive multi-dimensional GC. The progress made in interlaboratory studies and the availability of certified reference materials are discussed. 相似文献