46 



BURTON: Are you talking about glass ? 



KASHA: Yes, glass in hydrocarbon versus hydroxylic glass. 



ALLEN: I should like to get back to the ice for one more question. This 

 concerns the blue color of irradiated ice. Does the ice retain its blue color for 

 a long time above -170°? 



HOCHANADEL: I am not sure that we have noticed the blue color. 



GARRISON: Didn't you notice it in the cellulose in the cotton that you used? 



HOCHANADEL: Both cotton and kleenex irradiated with gamma rays in 

 liquid nitrogen appeared pale blue in color. However, this color was later at- 

 tributed to the presence of ozone produced by the radiation. 



ALLEN: As I remember, we used to see the blue color in irradiated ice. 



HOCHANADEL: We thought we saw blue color in ice. However, recently 

 we have irradiated large pieces of clear ice at -196°C and observed no visible 

 color. 



ALLEN: I was never sure it was the ice that was giving us the blue color, 

 rather than the container. 



PATT: I should like to interject a remark about the dry virus, which, I be- 

 lieve is pertinent to Dr. Pollard's earlier comment. An Argonne group (Bacho- 

 fer et al) (17) X irradiated dried bacteriophage at different temperatures in a 

 vacuum. They found that the inactivation efficiency decreased slightly, though 

 progressively, when the temperature fell from 37° to -196 C. The effect was 

 of the order that might be anticipated from an interaction with free radicals. 

 Some water is doubtless present in a dried preparation of this sort and may 

 contribute to the over-all inactivation. 



POLLARD: Adams has worked on that. I have done a lot of work on it, too, 

 quite independent of his work, actually, and in addition several members of my 

 group have irradiated catalase at different temperatures, both with deuterons, X 

 rays and ultraviolet, and there is a temperature effect in all cases. In the case 

 of viruses, the virus has a definite internal structure. I think for one thing it 

 has a protein coat and it has inside it a nucleic acid, and probably also water, 

 which may stay in this protected by the protein coat. But I think that the real 

 factor that concerns temperature in that case is the differential sensitivity of 

 the different constituents inside. If merely a simple assay is made on only one 

 it is very misleading, because it has a latent period, and if you allow for that, 

 which corresponds to damage and not to complete knocking out of the virus, you 

 get a totally different conclusion from the case where you actually assay for 

 virus regardless of latent period. So until all these factors are sorted out, it 

 is very dangerous to draw conclusions because there is a rate constant that you 

 think might fit water. I refuse to draw any conclusion myself, although we have 

 done a vast number of experiments on T-l phage. Because of this factor, this 

 internal structure makes it doubtful what one can do. Only lately we have found 

 that if you irradiate with alpha particles, which we have done, the cross section 

 fits pretty well with everything but the protein coat. 



PATT: Since we are also concerned with the effects in ice, I wonder 

 whether the chemists would care to comment about the work of Bonet-Maury. I 

 believe that he measured hydrogen peroxide formation after irradiation of ice 



