Szilard

Fermi and another European refugee, Leo Szilard, discussed the impact nuclear fission would have on physics and on the veiy unstable state of the world... 

Theorem 4-4 (Szilard, Kraft). A necessary and sufficient condition on the lengths n, 1 < j J, of the J code words of a binary prefix code is that... 

The Szilard-Chambers Reactions in Solids Carman Harhotlle and Norman Sutin... 

The study of Szilard-Chalmers reactions places considerable demands on the separation methods used. These molecular compounds are only weakly polar, if at all, and thus are not easily separable. Moreover, many of the compounds and especially the radicals and other intermediates formed are not very stable, often requiring the absence of air, moisture, and even light. Combining this with the fact that many of the product species are present in extremely small amounts, we have a nearly impossible situation. Nonetheless a good deal of reliable work has been done. 

In order to investigate chemical reaction mechanisms, it is useful to know the point at which the reaction starts. Regrettably, this is only rarely possible in Szilard-Chalmers studies, and is the object of one of the two most vigorous arguments in the field whether the bonds are all broken and there is a successive rebuilding of the molecules, or these is only a partial breakage of bonds, and little rebuilding is necessary. To illustrate with < 3 As, two possible sources of radioactive parent molecules are... 

Harbottle, G., Sutin, N. The Szilard-Chalmers Reaction in Solids. Advan. Inorg. Chem. Radiochem. /, 267—314 (1959). 

This recoil energy is so large compared to chemical energies that there seems to be no question about the atom s breaking loose from its bonds and travelling a considerable distance before coming to rest. The effect observed by Szilard and Chalmers is thus readily explained. 

The earliest studies in this field were conducted largely to benefit from the Szilard-Chalmers effect—namely, the separation of radioactive atoms from the bulk material—in order either to make nuclear chemical study of radioactive nuclides or to effect an enrichment of radioisotopes. In Table II are listed some selected works of this type. 

Early Studies of Isotope Enrichment by the Szilard-Chalmers Effect... 

Continuous culture systems have been widely used to culture microorganisms for industrial and research purposes (Kubitschek 1970 Tempest 1970 Veldkamp 1976 Rhee 1980). In recent years, these culture techniques have found their way into the bioassay methods of ecotoxicology and allelopathy (Rhee 1980). The early development of a continuous culture system can be traced back to the work of Novik and Szilard (1950 a,b) who developed the first chemostat. In a continuous culture system, nutrients are supplied to the cell culture at a constant rate and to maintain a constant volume, an equal volume of cell culture is removed. This allows the cell population to reach a steady state, where the growth rate and the total number of cells/ml of culture remains constant. Two kind of continuous culture systems can be distinguished turbidostat and chemostat. ... 

Novicik, A. and Szilard, L. (1950). Experiments with the chemostat on spontaneous mutations of bacteria. Proceedings National Academy of Sciences USA 36 708-719. 

A sample of iodine-128 was produced in a Szilard-Chalmers reaction by irradiating a sample of ethyl iodide in a neutron source. The radio-iodine was extracted with sodium thiosulfate solution and then counted in a Geiger counter at various time Intervals. Use the tabulated data of t in minutes against C counts/min to find the rate equation and the half time. 

The Szilard-Chambers Reactions in Solids Garman Harbottle and Norman Sutin Activation Analysis D. N. F. Atkins and A. A. Smales... 

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