Bulk Separation Research Articles

Changes in patterns of protein synthesis during the mammalian cell cycle

The pattern of protein synthesis during the G2 period of interphase in HeLa cells has been compared with the pattern of synthesis during an entire cell cycle in exponential growth. The patterns, as revealed by co-electrophoresis of the two populations of radioactive proteins on acrylamide gels, are very different. The differences are not due to selective or discontinuous degradation of proteins made radioactive during long or short exposures to tracer amino acids, nor do they arise from errors in the method of separation and counting. Similar differences are found between other phases of the cell cycle and the cycle as a whole, and between phases studied in pairs. Thus the reproductive cycle of eukaryotic cells not only involves translational shifts, an involvement already known to exist in consequence of studies in individual proteins, but it involves translational shifts of a magnitude sufficient for detection in bulk separation of the soluble proteins.

Bulk separation of chloroplast with intact membranes in the zonal centrifuge

Bulk separation of chloroplast with intact membranes in the zonal centrifuge

Improvement in Performance of Bulk Separation Equipment using Permanent Ceramic Magnets

Theoretical analysis of the performance of flat-plate permanent magnet separation equipment is presented, together with experimental confirmation. By the use of conformal mapping techniques, force on magnetic spheres along the magnet center line is found to be proportional to the square of surface flux density. Addition of a blocking magnet increases surface flux density and force with no increase in magnet size. Test data confirm the predicted increase in flux density and separating force.

Recovery of Fission Product Noble Gases

An advantage of using an absorption-stripping system over charcoal adsorption is that the noble gas can be removed almost completely in a coatinuous operation at ambieat temperatures. A difficulty with the Amsco absorption- stripping method is that relatively large volumes of organic have to be handled when operating at atmospheric pressure. The absorption-stripping system could be advantageously used where an inexpensive head end'' or primary bulk separation of gaseous activity is required, either for storage until safe disposal to the atmosphere is allowable, or for further processing for complete enrichment or purification of xenon and krypton. Other possibilities include the processing of homogeneous reactor purge gas streams, where a suitable carrier gas, such as helium, can be chosen to allow an increased single-stage concentration factor. This could also be used in processing gas streams from pyrometallurgical processing plants, where there is freedom in the choice of a vehicle gas in purging the gaseous fission products.

New Prospects in Isotope Separation

THE identification of the heavy hydrogen isotope and its separation gave considerable impetus to the search for methods of bulk separation of the isotopes of other elements. Previous to this time, the experimental man of science had been content to demonstrate that displacements of normal isotope ratios could be secured by one or other method. Aston and Harkins had shown that these ratios could be changed by diffusion processes in the cases of neon and chlorine. Bron-sted and Hevesy changed slightly the atomic weight of mercury by distillation methods. It was the separation of the hydrogen isotopes and the demonstration of their extraordinary utility in many problems of chemical, physical and biological interest that re-awakened the interest in more complete separations of other isotopic elements. The simultaneous advances in the study of the nucleus, by bombardment with swift-moving primary particles, enhanced the desire for individual isotopic species of the elements, at the same time that it provided an alternative tool for research in the form of artificially produced radioactive elements.