Preparation of bacteriologically safe bicarbonate concentrate for hemodialysis.

To determine whether bacteriologic hazards associated with bicarbonate concentrate may be reduced or prevented, evaluation of a system consisting of a mixing tank supplied with R.O. water and two separate storage tanks was undertaken. Bicarbonate was mixed on a schedule specific to usage and dispensed to the storage tanks from which it was drawn off into 2.5 gallon jugs for each treatment. The mixing tank was disinfected with hypochlorite solution (200 ppm) before each use. Storage tanks and 2.5 gallon jugs were disinfected weekly and sampled immediately before scheduled disinfection and after the longest storage time. The mixing tank was sampled for corresponding batches. A 1 ml inoculum of concentrate was plated onto tryptic soy sheep blood agar, incubated for 48 hours at 35 degrees C and colony counts/ml recorded. A total of 225 batches on a 10% sampling schedule were monitored. All cultures have grown less than 50 cfu/ml, which is less than AAMI standards for maximum allowable level for water and dialysate. Bacteriologically safe bicarbonate concentrate can be reliably produced using R.O. water, controlled storage times, and rigid disinfection schedules.

Eleven-year variation in polar ozone and stratospheric-ion chemistry.

A mechanism for producing an 11-year oscillation in ozone over the polar caps is the modulation of galactic cosmic rays by the solar wind. This mechanism has been shown to give the observed phase in ozone oscillations and the correct qualitative dependence on latitude. However, the production of nitrogen atoms from cosmic-ray collisions seems inadequate to account for the ozone amplitude. Negative ions are also produced as a result of cosmic-ray ionization, and negative-ion chemistry may be of importance in the stratosphere. Specifically, NO(x)(-) may go through a catalytic cycle in much the same fashion as NO(x), but with the important distinction that it does not depend on oxygen atoms to complete the cycle. Estimates of the relevant rates of reaction suggest that negative ions may be especially important over the winter polar cap.

Possible consequences of nearby supernova explosions for atmospheric ozone and terrestrial life.

Hard x-ray pulses or increased cosmic radiation originating in nearby supernova explosions may be capable of temporarily removing most of the earth's atmospheric ozone cover even when direct radiation effects at the earth's surface are negligible. Consequently, terrestrial life may be subject to relatively huge solar ultraviolet fluxes every few hundred million years.