Slow-releasing mechanism

Substances which function as tissue adhesives have the unique ability to remain in contact with tissues in localized areas for prolonged periods of time. Not only does the tissue adhesive function as a glue but it has the capacity to serve as a slow release mechanism for drug delivery as it is biodegraded. 

With EPS, the AHAs penetrate far more evenly because of the type of vehicle used and the slow-release mechanism, which eliminates the need for pre-peel preparation. The different types of AHAs used in EPS are important the three AHAs in the solution actually penetrate at different speeds. Small molecules penetrate the skin more rapidly than larger molecules the glycolic acid is therefore the first to penetrate, followed by the lactic acid and finally the mandelic acid, the largest molecule, which relies on the lytic action of the other acids on the corneodesmosomes to help it penetrate the skin more easily. 

Design of polymer-bound fungicides can accommodate a slow release mechanism or a permanently attached biocide. The chemical linkages used to attach fungicides to polymers could either be hydrolyzable or nonhydrolyzable depending on the type chemical... 

According to their resuits, the ioaded Ag ions into the grafted /S-CD cavities exhibit excelient antibacteriai fiinctionaiity with slow release mechanism... 

Hurst, J. L., Robertson, D. H. L., Tolladay, U., and Beynon, R. J., 1998, Lipocalins in mouse urine provide a slow release mechanism for oUactoty signals, vlnrm. Behav. 55 1289-1297. 

Additional constituents have been introduced to epoxy-silica hybrids to achieve specific properties. For instance, the incorporation of small amounts of a sUane-functionalized perfluoroether oligomer has been found to considerably reduce the surface energy of membranes. This has been attributed to the migration of the ftuoroligomer-derived species from the bulk to the surface, which continues even after curing, through a slow-release mechanism 14]. 

Recently, Ciba Specialty Chemicals introduced nanocapsules with antimicrobial products. Washing durabihty is obtained by engineering the cotton surfaces with a covalently bonded encapsulation system, which enables the controlled dehvery of antimicrobials. As a consequence of a slow-release mechanism, a small quantity of active material is released step-by-step. In short, the new system captures the best of both worlds permanently fixed capsules to achieve durability, and mobile antimicrobials to inhibit bacterial growth on the entire surface (Fig. 7.14). 

Figure 2. Slow-releasing mechanism(Reproducedfrom reference 16, copyright American Association of Textile Chemists and Colorists, AATCCJ...

Coatings, Paints, and Pigments. Various slightly soluble molybdates, such as those of zinc, calcium, and strontium, provide long-term corrosion control as undercoatings on ferrous metals (90—92). The mechanism of action presumably involves the slow release of molybdate ion, which forms an insoluble ferric molybdate protective layer. This layer is insoluble in neutral or basic solution. A primary impetus for the use of molybdenum, generally in place of chromium, is the lower toxicity of the molybdenum compound. 

Agronomic Properties and Nutrient Release Mechanism. The conversion of UF reaction products to plant available nitrogen is a multistep process, involving dissolution and decomposition. Materials are slow to enter the soil solution by virtue of their low solubiUty. Longer polymer chain products are less soluble than shorter chains and take longer to become available to the plants. 

The mechanism responsible for improved delivery of lipophilic drugs has not yet been clarified. Absorption of liposomes by cells is unlikely. Adsorption to cells followed by slow release of the drug from the liposome, either via diffusion through the thin aqueous tear film or via direct partitioning from the membrane of the vesicle to the membrane of the cell, was proposed as a possible pathway. 

Silver and mercury salts have a long history of use as antibacterial agents.241-243 The use of mercurochrome ((40), Figure 18) as a topical disinfectant is now discouraged. Silver sulfadiazene (38) finds use for treatment of severe burns the polymeric material slowly releases the antibacterial Ag+ ion. Silver nitrate is still used in many countries to prevent ophthalmic disease in newborn children.244 The mechanism of action of Ag and Hg is through slow release of the active metal ion—inhibition of thiol function in bacterial cell walls gives a rationale for the specificity of bacteriocidal action. 

Release mechanisms are classified into wide and limited aperture releases. In the wide aperture case a large hole develops in the process unit, releasing a substantial amount of material in a short time. An excellent example is the overpressuring and explosion of a storage tank. For the limited aperture case material is released at a slow enough rate that upstream conditions are not immediately affected the assumption of constant upstream pressure is frequently valid. 

Wray The speed of the Ca2+ release seems to be important faster rises will stimulate these mechanisms better than slow ones. For example, if we put on CPA or thapsigargin, often we will see a substantial elevation of basal Ca2+, but it is quite slow. We don t see a corresponding rise of the basal level of force production in many of the tissues. It seems that there is a lot of Ca2+ there but the contractile machinery is not interested in it. It will presumably also be the case that extrusion mechanisms handle small, slow releases, and hence little or no contraction. 

Murch S. J., Cox P. A., and Banack S. A. (2004). A mechanism for slow release of biomagnified cyanobacterial neurotoxins and neurodegenerative disease in Guam. Proc. Natl. Acad. Sci. USA 101 12228-12231. 

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