Atomic-scale structure of GeSe2 glass revisited: a continuous or broken network of Ge-(Se(1/2))4 tetrahedra?

The atomic-scale structure of germanium diselenide (GeSe(2)) glass has been revisited using a combination of high-energy x-ray diffraction and constrained reverse Monte Carlo simulations. The study shows that the glass structure may be very well described in terms of a continuous network of corner- and edge-sharing Ge-Se(4) tetrahedra. The result is in contrast to other recent studies asserting that the chemical order and, hence, network integrity in GeSe(2) glass are intrinsically broken. It is suggested that more elaborate studies are necessary to resolve the controversy.

Diffusion and nucleation of gas in gel and some implications for the development of decompression procedures.

Attention is directed to certain incongruities among accepted diving procedures in order to emphasize the need for a more complete understanding of the interactions between the factors involved in diving and decompression and in the onset of decompression sickness. It is suggested that physiological responses derived from the effects of diffusion and nucleation of gas in tissue might be interpreted in terms of similar events in specimens of gelatin subjected to patterns of compression and decompression. A model for behavior of specimens in gel is developed and conformity with the results of a program of experimentation is demonstrated. With the insight provided by this model, a substantial analogy between important aspects of the behavior of gel and tissue is claimed and application of this model to the refinement and development of diving and decompression procedures is proposed.