Physico-chemical changes accompanying the irradiation of ammonium molybdophosphate (AMP) with electrons up to a dose of 200 MGy have been studied by X-ray di †raction, SEM, EDX, thermal analyses, EPR and NMR measurements. The ion exchange characteristics of the control and irradiated AMP with respect to Cs`have been studied using simulated acidic nuclear waste solutions in a column. Apparent equilibrium constants for the Cs`ÈH`exchange have been calculated from breakthrough curves. Structural breakdown occurred on irradiating AMP to a dose of 100È200 MGy and was partially converted to and MoO 3 ammonium molybdate. Although the useful exchange capacities of the irradiated AMP were reduced, the apparent ion exchange selectivity for Cs`(with respect to H`) improved as compared to the control AMP.

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The morphological change of cerebral cortex astrocytes from protoplasmic to glial fibrillary acidic protein (GFAP)-containing cells is induced by injury. Protoplasmic astrocytes that contain no detectable amount of GFAP become filled with GFAP and their processes extend to form the glial scar around the wound. It is hypothesized that this transformation is induced by cAMP and neurotransmitters released from damaged neuronal cells. A similar mechanism may be present in other brain regions following injury or disease.