Adhesion discs

Contacts of another type, known as septate desmosomes or adhesion discs, form a belt around the cells of invertebrate epithelia. In these contacts a space of 18 nm between adjacent cell membranes is bridged in a number of places by thin walls. Behind the desmosomes the membrane is often backed up at these points by an electron-dense region to which are attached many fine microfilaments of -6-10 nm diameter (Fig. 1-15, D). 

Pierard, G.E., Pierard-Franchimont, C., Saint-Leger, D., and Kligman, A.M. Squamometry the assessment of xerosis by colorimetry of D-squame adhesive discs. J. Soc. Cosmet. Chem. 47, 297-305... 

Schatz, H., Kligman, A.M., Manning, S., and Stoudemayer, T. Quantification of dry (xerotic) skin by image analysis of scales removed by adhesive discs (D-Squames ). J. Soc. Cosmet. Chem. 44, 53-63... 

Miller, D. D-Squame adhesive discs. In Bioengineering of the skin skin surface imaging and analysis. Wilhelm, K.P., Eisner, P., Berardesca, E., and Maibach, H.I. (Eds.). CRC Press, Boca Raton, pp. 39 16 (1997). 

This organism exhibits only two life cycle forms the vegetative bi-nucleate trophozoite (10-20 pm long by 2-3 pm wide) (Fig. 6.2d) and the transmissible quadra-nucleate cyst (10-12 pm long by 1-3 pm wide). Trophozoites have four pairs of flagella and an adhesive disc, which is thought to help adhesion to the intestinal epithelium. Division in trophozoites is by longitudinal fission. 

At the end of this procedure, the catheter needs to be secured externally. We prefer an external fixation device (adhesive disc) to secure the catheter. An adhesive cloth tape is wound around the catheter like a flag, a few centimeters from the disc. A 2/0 silk suture is then used to take sutures on the external disc and firmly tied along the length of the adhesive... 

This technique permits the study of the gross features of a bound vesicle, such as its contour radius or the size of the adhesion disc, and also of the fluctuation spectrum of the bound part. This experiment shows clearly that the problem of a vesicle adhering to a substrate has two complementary aspects, a macroscopic one (overall shape) and a mesoscopic one (fluctuation spectrum in the vicinity of the substrate). In a first step, recognizing this distinction is key for a successful theoretical modeling of this problem. In a second step, the two aspects must be reconciled self-consistently. 

Three-day-duration system in the form of an adhesive disc, worn on a few square centimeters of skin surface, for transdermal systemic delivery of a drug for motion-induced nausea (17,18). 

Two wooden beams are butt-jointed using an epoxy adhesive (Fig. A1.3). The adhesive was stirred before application, entraining air bubbles which, under pressure in forming the joint, deform to flat, penny-shaped discs of diameter 2fl = 2 mm. If the beam has the dimensions shown, and epoxy has a fracture toughness of 0.5 MN mT , calculate the maximum load F that the beam can support. Assume K = cT Tra for the disc-shaped bubbles. 

In terms of processing there is no need for pre-drying PCHE granules, a standard extruder screw as used for polycarbonate may be used and discs are said to release well from the mould. Question marks remain on the oxidative stability of the polymer and on the quality of adhesion of the reflective layer but Dow claim that metallising is possible. 

Traditionally, UV curable polymers have been utilized as coatings for wood and vinyl floors, but their applications have increased dramatically over the last twenty years to encompass many diverse areas, including optical fiber coatings (7), adhesives (2), disc replications (3-5), and microelectronics (6). This widespread use of UV cross-linked systems is attributed to their rapid, energy efficient curing and their solvent free, one piece formulations. Typically, UV curable systems require only a small fraction of the power normally utilized in thermally cured systems and their solvent free nature offers an environmentally safer alternative. 

DISC ADHESIVE 1.25" DIAMETER 11/32" APERATURE DOUBLE FACED 612S 6515012478232 PG 35.26 ... 

The analysis takes place in a circular disc called the transfer disc or rotor (Figure 6.1) made of an inert material such as Teflon or acrylic whose surface properties allow minimal adhesion of liquid. It contains radially arranged sets of cavities, each set composed of two or more interconnected cavities, one for the sample and the others for the reagents (Figure 6.2). Small measured volumes of sample and reagent, e.g. 5 - 200/rl, are automatically pipetted into the appropriate wells so that each set contains a different sample but the same... 

The major uses of BPA are in the production of polycarbonate resins (63%) and epoxy resins (27%). Polycarbonates have major outlets in automotive parts, compact discs, eyeglasses, and sheet and glazing applications, and have caused bisphenol A consumption to more than double during the past decade. Epoxy resins are two-component adhesives for very strong bonding. Miscellaneous uses include flame retardants (mostly tetrabromobisphenol A) and other polymer manufacture. Polycarbonate grade bisphenol A is >99% p,p isomer. The epoxy grade is 95% p,p. The p,p and o,p isomers can be separated by a combination of distillation and crystallization. 

Spin coating utilizes centrifugal forces created by a spinning substrate to spread a liquid evenly over its surface. Current applications are in photoresist technology for the microelectronic industry and in the manufacture of protective overcoats and adhesives for the optical storage industry (compact discs and DVDs).5... 

It was hypothesized that the imbibed fibronectin may have been washed out by the medium, and this could have affected adhesion in sections of the disc. To eliminate this possibility, samples of the composite were made with gelatin dissolved in the aqueous phase. They were then emulsified with the hydrophilic prepolymer and applied to the reticulated foam. The result was covalent bonding of some of the protein into the polymer backbone, thus making it immune to washout. Figure 6.6 reports counts of endothelial cells cultured on this formulation and effects of sterilization method compared to controls without gelatin. 

Dipping method for adhesive coating of the metal discs is the best method for moulded rubber products manufacture while the quality control required is frequent checks on viscosity and solid content of the dipping bath. The later will be maintained by slow and constant agitation both vertically and horizontally in the bath. 

Where wet adhesion was to be measured, discs 31 mm in diameter were punched from the panels and bonded in the same manner, except that all discs were kept water wetted until bonded, and the alignment jigs stored at 100% RH. Specimens were removed and tested with minimum delay to avoid drying out. 

To determine the wet bond strength coated panels were immersed in distilled water for 1500 h, removed and discs 25.4 mm in diameter stamped from them. The surfaces were wiped with a dry tissue and bonded between two cylindrical test pieces using a polyamide cured epoxide adhesive and immediately placed in a sealed container at 100% RH for the adhesive to cure. After 16 h the specimens were broken on an Instron Universal Test Machine with minimum delay. Recovered values were measured after the panels had dried out at room temperature and humidity for 7 days. Clearly, it is unlikely that the values reported represent the minimum bond strengths, as some drying out is almost inevitable, but the values are directly comparable. 

The effect of silanes on the bond strength of two epoxide adhesives to glass is shown in Table 13. The test mode was that of Sandwich Butt Tensile in which a glass disc was bonded between two aluminium specimens in the form of a sandwich, and the resulting composite specimen broken on an Instron Universal Test Machine. Clearly in such a composite test specimen, alignment is important and there are many potential sites and modes of failure. 

The adhesion of platelets to the subendothelial matrix via specific adhesive GPs is the initial step in primary hemostasis. Binding of platelets to the matrix results in rapid (Fig, 2) morphological conversion of platelets from flat discs to spiny spheres. 

To measure the adhesion strength of bacteria, it is necessary to remove them from the surface. Weiss (1961) measured bacterial adhesion by allowing cells to settle onto a glass surface of a sealed chamber, and then counting them with the aid of a microscope. After a period of incubation the chamber was turned upside down, the unattached cells fell from the surface and the remaining attached cells were recounted. This adhesion number method is purely observational, as it does not measure adhesion directly. Weiss also described a disc-shearing device,... 

The above procedure was also employed to investigate buccal absorption from the HEMAC experimental delivery device. As in the case of the diffusion cell the drug-loaded disc was positioned on the inner central surface of the buccal mucosa. An impermeable film coated with mucosal adhesive (F-4000, Adhesives Research, Glen Rock, PA) on the periphery was then positioned over the HEMAC disc to prevent dehydration and to secure the device in place on the mucosal surface. The disc was allowed to remain in contact with the mucosa for 4 h before it was removed for quantitation of residual drug content. Blood samples were collected over the same interval as for the saturated solution and processed in the same manner. 

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