The controlled incorporation of guest molecules in zeolites opens the way to novel materials with desirable optical, magnetic, or electronic properties. The properties of the guests are often direction dependent and therefore the bulk orientation of the host matrixes (see figure) in an electric field can lead to greatly enhanced performance.

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Non-contact removal of oral biofilms offers advantages beyond the reach of bristles, but it is unknown how energy transfer for removal from brush-to-biofilm occurs. In the present study we evaluated non-contact, oral biofilm removal by oscillating-rotating and sonic toothbrushes, and their acoustic output up to 6 mm distance. Whereas some brushes removed biofilm when used at a distance of up to 6 mm, others lost efficacy at a distance of 2-4 mm from the biofilm. Loss of efficacy was accompanied with high standard deviations and volumetric biofilm expansion. Both sonic and oscillating-rotating brushes caused fluid flows and the inclusion of air-bubbles, while non-contact acoustic energy-transfer was demonstrated to decay with distance for both types of brushes. We put forward the following mechanism for non-contact removal: (i) brush energy is absorbed by biofilm, resulting in the visco-elastic expansion of the biofilm; (ii) if the energy absorbed is sufficient and deformation is beyond the yield point, biofilm removal occurs; and (iii) if deformation is in the plastic range but below the yield point (i.e. at the limiting distance for non-contact removal), biofilm is expanded but not removed.

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Starting from the necessity for more substantial evidence with regard to the Occurrence of intracrystalline diffusion as the rate-limiting transport mechanism in sorption processes on zeolites, the variation of zeolite crystal size is regarded as a criterion and used in the case of the sorption system n-hexane/MgA zeolite.The experimental study has been carried out by using a constant volume variable pressure system. The uptake curves have been analysed by solution of the appropriate diffusion equation on the assumption that the uptake rate obtained is limited by intracrystalline diffusion. An additional analysis was done considering the sorption process as being limited by surmounting a transport resistance in the surface region of zeolite crystals.The experimental parameters covered the following ranges : temperature : 373-623 K, pressure : w 4 x 10-3-265 Pa, amount sorbed : m 2 x 10-4-3 x 10-1 mmol g-l, crystal size (mean edge length of cubic crystals) : 0.7-43 pm.Over the whole of the ranges of amount sorbed and crystal size the apparent diffusion coefficient