Non-aqueous-phase-liquid breakthrough during evaporative drying of clay barriers.
In this study, an attempt has been made to model a real field scenario, whereby an initially almost saturated clay liner in a waste site is gradually drying, due to evaporation at its lower boundary. A detailed conceptual model that deals with the penetration and breakthrough of non-aqueous-phase-liquid (NAPL) in clay liners is introduced. Water content of clay samples was monitored during ambient evaporation through apertures at the base of sample holders. Clay drying rate served as the primary parameter for the NAPL breakthrough study. The interconnection between drying rates, structural damage formation (cracks and suction) and NAPL penetration is especially addressed. The processes taking place in the clay samples during drying appear to be associated with the capillary effects between the different fluid phases in the vicinity of either the NAPL-clay or the clay-air boundaries. A conceptual model of NAPL penetration and breakthrough of the clay layer has been considered, based on both indirect and direct observations of structural damages produced on either clay boundaries. A mutual interaction between these two boundaries is suggested and discussed. NAPL breakthrough is suggested to take place through cracks initiated on the upper soil surface.
Factors Affecting the Interlayer Expansion of Vermiculite and Montmorillonite with Organic Substances1
An evaluation of the factors affecting interlayer expansion of the mica type layered minerals was made by X-raying various dehydrated forms of montmorillonite and vermiculite while immersed in liquids of varying dipole moments and dielectric constants. The results showed that the extent of interlayer expansion was determined by the size, charge, and total amount of the interlayer cations and by the magnitude of the dipole moment and the dielectric constant of the immersion liquid. The results were explained on the basis of the nature of the electrostatic interlayer attractive forces within the crystal lattice itself and by the laws governing complex formation between charged particles. View complete article To view this complete article, insert Disc 2 then click button8
Anaesthetic aspects of bronchial fistula.
SINCE the term bronchial fistula can, from the practical point of view, be applied to any abnormal connection between the inside of the intrathoracic respiratory system and the outside, it includes a very wide assortment of cases. Fistulae vary in their acuteness and duration from a few minutes up to thirty years or more (Huizinga and Smelt, 1950), and in their consequences from the rapidly fatal to the almost insignificant. Although the anaesthetic management of these cases falls mainly within the province of those working in specialized units, any anaesthetist may be caught unawares from time to time. Quite apart from this consideration the subject is well worth discussing because of its intrinsic interest and because it has probably called for as much anaesthetic ingenuity and resourcefulness as any other subject within the specialty.