To determine the relative biological effectiveness of 252Cffission neu trons versus *°Co 7-rays for inducing liver tumorigenesis, C57BL/6NCrj x C3H/NOJ F,, hereafter called B6C3F,, mice were irradiated once either with 252Cfor "Co and the tumorigenicity of the two types of radiation was studied. Individual groups of B6C3F] mice (about 30 mice/group) were irradi ated once with 252Cfat doses of ...

Sir: In our laboratories two strategies for obtaining mass spectra of involatile and/or thermally unstable natural products have been used. One is an optimization of sample vaporization, which involves rapid sample heating followed by thermal desorption and ionization under chemical ionization (CI) conditions, that is emitter CI mass spectrometry (emitter CIMS). Recently, we have reported a pre...

The development of powerful new mass spectrometric techniques such as electrospray ionization (ESI)1 and matrix-assisted laser desorption ionization (MALDI)2 has been driven by the polymer and biological sciences. Workers in other areas, for whom conventional techniques are less useful, such as cluster chemistry, are now embracing these ionization methods. The mass spectrometric characterizatio...

Based on a recent experimental finding which may suggest the existence of a tri-nuclear molecular structure before the cold ternary fragmentation of 252Cf takes place, we solved the eigenvalue problem of a certain class of vibrations which are very likely to occur in these molecules. These oscillations are the result of the joined action of rotations of the heavier fragments and the transversal...

The title study has been made by using a time-of-flight mass spectrometer, placing primary emphasis on fragmentation reactions and rates. The mass spectrometer was modified so that segmented fields with segments of different magnitudes could be applied in the ion acceleration region and retarding potentials in the region between the flight tube and the ion detector. Methods using these retardin...