[en] Short communication

[en] The anthropogenic effect upon the activity of ¹⁴C (¹⁴CO₂) in the atmosphere and in the terrestrial biota was examined. Some new results associated with fossil CO₂ emissions into the air were also obtained based on monitoring data from Prague-Bulovka and from other sites in the Czech Republic, Germany, Hungary, and Switzerland. Although a rather uniform annual decrease in atmospheric ¹⁴CO₂ has been observed over the past decade, the mean amount of ¹⁴C (¹⁴CO₂) in the atmosphere seem to have been stable since 1994. This can be explained in terms of a prevailing influencing of the global Suess effect by fossil carbon emission. A stable amount of ¹⁴C (¹⁴CO₂) in the atmosphere, as a tracer of atmospheric CO₂, indicates a stable CO₂ delay time (without any cumulation effect), which seems to be independent of actual CO₂ concentration

[en] Short communication

[en] This paper presents a combustion model of nano-and microsized aluminum mixture frozen in water. The model takes into account combustion of aluminum particles in water vapor, the motion of combustion products, the temperature and velocity differences between particles and gas. The obtained results of the combustion rate depending on pressure and mass ratio between dispersed Al powders are in good agreement with the experimental data described in scientific literature. (paper)

[en] Published in summary form only

[en] Graphite from the dismantling of nuclear reactors is crushed and incorporated in an aqueous medium (solid material < 35 wt%) containing surfactants then the suspension is foamed by a pressurized oxidizing gas (oxygen or enriched air). The aim of the invention to decrease the volume of wastes after incineration: particulates and nitrogen oxides

[en] Called an academinc curiosity only a few years ago the cage-like fullerenes now receive a lot of interest from research institutes and industry. The soot-containing combustion of hydrocarbons could become a low-cost source for this type of carbons. (orig.)

[en] BL9.0.2.2 is the newly constructed experimental End Station 2 at the Chemical Dynamics Beamline 9.0.2 of the Advanced Light Source (ALS). It is dedicated to the high resolution photoionization study of molecules of interest to atmospheric and combustion chemistry. This End Station is equipped with a high resolution scanning monochromator, which has been demonstrated to have a world record resolution of E/δE=70,000. Taking the advantage of the high resolution ALS light, the authors have improved the energy resolution in threshold photoelectron spectroscopy (TPES) to 0.8 meV. The TPES is a popular technique for photoionization experiments at all synchrotron radiation facilities due to its high energy resolution as compared to that of traditional photoelectron spectroscopy (PES). TPES achieves higher energy resolution by preferentially detecting near zero kinetic energy photoelectrons resulting from threshold photoionization. However, the spectra obtained from the TPES technique generally are complicated by the simultaneous detection of electrons with nonzero kinetic energy, which are not fully discriminated against. On the other hand, the spectra obtained from pulsed field ionization photoelectron spectroscopy (PFI-PES) are completely free of the contamination from kinetic electrons. The PFI-PE technique basically involves the detection of the photoelectrons from field ionization of the very high-n Rydberg states, a few cm^-1 below the ionization energy (IE), by applying a delayed pulsed electric field. Within a delay of a few microseconds, all the prompt electrons formed from direct ionization will escape from the photoionization region and will not be collected. The authors have recently overcome problems with energy resolution of an electron time-of-flight technique, and incorporated the PFI-PE technique with multi-bunch VUV synchrotron radiation

[en] The study on deflagration-to-detonation transition (DDT) is very important because this mechanism has relevance to safety issues in industries, where combustible premixed gases are in general use. However, the quantitative prediction of DDT is one of the major unsolved problems in combustion and detonation theory to date. In this paper, the DDT process is studied theoretically and the critical condition is given by a concise theoretical expression. The results show that a deflagration wave propagating with about 60% Chapman–Jouguet (CJ) detonation velocity is a critical condition. This velocity is the maximum propagating velocity of a deflagration wave and almost equal to the sound speed of combustion products. When this critical condition is reached, a CJ detonation is triggered immediately. This is the quantitative criteria of the DDT process. (paper)

[en] Short communication