Particle bursts

If the temperature reaches the ignition temperature of the dust particles, the dust particles burst into flame. 

Pulsed plasmas containing hydrogen isotopes can produce bursts of alpha particles and neutrons as a consequence of nuclear reactions. The neutrons are useful for radiation-effects testing and for other materials research. A dense plasma focus filled with deuterium at low pressure has produced 10 neutrons in a single pulse (76) (see Deuterium AND TRITIUM). Intense neutron fluxes also are expected from thermonuclear fusion research devices employing either magnetic or inertial confinement. 

This experiment does have some features of a direct vision observation. First, the glowing spot is directly visible. Second, it is easy to imagine an invisible stream of particles hurtling through the triangular hole in the electrode to crash against the fluorescent screen in a burst... 

While the major application of albumin microspheres is in the area of chemotherapy, there have been studies reporting the release of such varied compounds as 1-norgestrel (97), insulin (98), and hematoporphyrins (99) from bovine serum albumin, and the antibacterial sulfadiazine from ovalbumin (100). In general, burst phenomena are found for all systems studied. However, the results from the insulin study are worthy of note in that blood glucose levels were depressed for more than 14 days following the administration of insulin-containing BSA microspheres to diabetic rats. The smaller microspheres were absorbed by day 28 and the larger particles by day 56. 

Particularly high stress occurs when bubbles burst on the surface of the liquid, whereby droplets are eruptive torn out of the surface [32-36]. According to theoretical calculations, maximum energy densities occur in the region of the boundary surface shortly before the droplets separate [36]. The results calculated by Boulton-Stone and Blake [34] show that these are exponentially dependent on bubble diameter dg. Whereas these authors found values of e = lO mVs with dg = 0.5 mm, these are only e 1 m /s with dg = 5 mm. The situation may be different regarding the droplet volume separated from the surface by the gas throughput and thus the number of particles which are exposed to high stress. The maximum for this value occurs with a bubble diameter of dg = 4 mm (see [34]), and it is therefore feasible that there could be an optimal bubble size. 

A further hazard exists when compressed air jets are used to clean machine components in workplaces flying particles have caused injury and blindness. Cylinders may fail if overpressurized or weakened by the application of heat. Liquefied gases, e.g. butane or propane, respond more rapidly to heat than the permanent gases such as nitrogen or oxygen. Cylinders are normally protected by pressure relief valves, fusible plugs or bursting discs. 

Rumscheidt, F. D., and Mason, S. G., Particle motions in sheared suspensions. XII. Deformation and burst of fluid drops in shear and hyperbolic flow. J. ColloidScL 16,238-261 (1961). Rwei, S. P., Manas-Zloczower, I., and Feke, D. L., Observation of carbon black agglomerate dispersion in simple shear flows. Polym. Eng. ScL 30, 701-706 (1990). 

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