Abstract: Pressure swing adsorption process for the recovery of high purity oxygen from a feed gas comprising oxygen, nitrogen, and argon. The process includes a forward flow stage which comprises (a) passing the feed gas into a first adsorption zone containing an adsorbent selective for the adsorption of nitrogen over oxygen and argon, and withdrawing therefrom a nitrogen-depleted intermediate gas; (b) passing the nitrogen-depleted intermediate gas into a second adsorption zone containing an adsorbent which is selective for the adsorption of nitrogen over argon and selective for the adsorption of argon over oxygen; (c) withdrawing an oxygen-enriched product gas from the second adsorption zone; and (d) terminating the passing of feed gas into the first adsorption zone and withdrawing an oxygen-enriched depressurization gas from the second adsorption zone in the same flow direction as (c).

Abstract: An AgX-type zeolite having a silver exchange level of 20-70% and a Ar/O2 Henry's law selectivity ratio at 23° C. of 1.05 or greater has an optimum combination of selectivity for argon over oxygen at lower cost than higher silver exchange levels. This material can be used in oxygen VSA/PSA processes to produce oxygen at purities above 97%.

Abstract: An AgX-type zeolite having a silver exchange level of 20-70% and a Ar/O2 Henry's law selectivity ratio at 23° C. of 1.05 or greater has an optimum combination of selectivity for argon over oxygen at lower cost than higher silver exchange levels. This material can be used in oxygen VSA/PSA processes to produce oxygen at purities above 97%.

Abstract: A system and method for using double-evoked otoacoustic emission (2EOAE) signals to elicit an evoked response from the cochlea. A three sample stimulus includes a first signal, a time delayed second signal and the superposition of the first and second signals. The time delay is selected to be less than the maximum latency of the cochlear emission. Each of the three signals elicits a response from the cochlea that include a linear response. The linear response is eliminated by subtracting the response to the first and second individual signals from the response to the superposition signal. One class of signals arises when the time delayed signal is a scaled version of the first signal. The signals can include click signals, chirp signal and the like. Chirp signals can be used to mimic classical distortion product (DP) responses. The signals may be presented using a single acoustic source or separate acoustic sources.