Coatings continued specimen preparation

The retardation of the migration of silicone oligomers from the silicone tubing after being coated indicates that the plasma polymer coating applied to the tube substrate is in a form of continuous film with barrier characteristics instead of some other physical forms (e.g., powder). Direct evidence of this aspect can also be seen from the fact that all test specimens prepared had passed the dye penetration test. 

Support films generally used for microscopy above 50000x magnification are either perforated, holey, carbon coated plastic, or holey carbon films for highest resolution. In the case of holey plastic supports, the presence of moisture or some other immiscible liquid in the solution used for coating will provide holes in the films. A fuller discussion on this topic is found in the specimen preparation text by Goodhew [5]. In our experience, moisture from the air or from one s breath on the slide causes the formation of holes and, in fact, it may be more difficult to prepare continuous films. These perforated supports provide an area of the specimen supported by the film with other areas suspended over the holes. 

Continue with Subheading 3., step 18 in the method. The positive reaction product with this chromogen will be red, with the nuclei a light blue. Rather than dehydrating the specimens in ethanol and xylene, allow them to dry, add 1 drop of Crystal/Mount (Biomeda Corp, Foster City, CA) to the specimen and bake them in a 60°C oven for 30 min. This preparation is permanent and can be cover-slipped with Permount if needed. The Crystal/Mount will form a hard plastic coating on the slide, but it can be damaged by smudging. 

For case 3, pieces of Al-foil were cut from a roll of fabricated material as shown in Fig. 1(a). The laminate in case 3 was then prepared in a Haake film extruder with a 36 pm Polyester (PET) as carrier (see Fig. 1(b)). The foil was mounted on the PET carrier while LDPE was extruded and coated on Al-foil at a melting temperature of 278 °C. A nip with the pressure 202 bar was used to press the layers together. The laminated specimen for case 3 was than cut from roll including PET/Al-foil/LDPE as shown in Fig.l(c). After producing the material for case 3, LDPE was continuously extruded on the PET carrier under the same conditions but without the Al-foil. By peeling off the PET carrier, the LDPE produced here was used for making the specimen for case 2 and case 4. And the specimen of case 1 is taken from the Al-foil roll of the same direction as the other cases. 

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