Escape-only masks

Air-purifying full-facepiece respirator with chemical canister (gas mask) Self-rescue mouthpiece respirator (for escape only)... 

In principle, the magnitude of the secondary yield at beam energies E > Ej is a function of the chemistiy of the surface since the secondary yield varies slowly with atomic number. However, in most current SEMs the vacuum is sufficiently poor that the surface is always covered with many monolayers of contamination, such as hydrocarbons, deposited from the pumping system. Because the secondary electrons can escape only when produced within a few nanometers of the surface, changes due to the surface chemistry are therefore usually masked. 

All normal precautions should be observed during the handling of these large quantities of ammonia and sodium. A well-ventilated hood, a gas mask, and a bucket of sand were available to the submitters. The only hazard in this reaction may arise if too much ammonia escapes and the sodium does not react properly as a consequence. The addition of 0.5-1.0 1. of ammonia to the reaction mixture after the sodium has been added is a useful precaution. 

In order for the transference relationship to escape these effects, the analyst would have to strip the narcissistic image of his own ego of all the forms of desire by which that image has been constituted, reducing it to the only face that sustains it behind their masks the face of the absolute master, death. ... 

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