Light Sensitive Gels

A solid emulsion is a suspension of a liquid or solid phase in a solid. For example, opals are solid emulsions formed when partly hydrated silica fills the interstices between close-packed microspheres of silica aggregates. Gelatin desserts are a type of solid emulsion called a gel, which is soft but holds its shape. Photographic emulsions are gels that also contain solid colloidal particles of light-sensitive materials such as silver bromide. Many liquid crystalline arrays can be considered colloids. Cell membranes form a two-dimensional colloidal structure (Fig. 8.44). 

Stains All is light-sensitive and bleaches slowly at the air. The stained gel should dry in a vacuum gel dryer immediately after destaining and documentation. 

Scientific research has proved in recent years that the rind and the outer leaf, normally thrown away, contain much more active therapeutic ingredients. On the other hand, the gel is sensitive to heat and light, and can quickly deteriorate at high temperature. For these reasons, the gel is now available as a cold-processed extract obtained from aloe whole leaf. The fresh whole leaf is cut into small pieces and whipped to yield a homogeneous yellowish or reddish material. The product (10% aloe leaf and 90% water), concentrated, and in some cases deprived partially of aloins, is bitter. 

We have employed a variety of procedures for removing free iodide from the iodinated proteins. This can be accomplished by (a) gel filtration, (b) dialysis, and (c) use of ion exchange resin. Gel filtration is a very effective method for removal of both iodide and lactoperoxidase if the molecular weight of the iodinated protein and the molecular weight of the enzyme are sufficiently different as in the example given. Since the iodine derivatives are light sensitive all procedures should be carried out in dim light. 

The submicron-sized and nanosized light-sensitive polyelectrolyte containers have been proposed and laser-stimulated release of corrosion inhibitor from their inner volume was studied. It was shown that the release of corrosion inhibitors from containers embedded into the silica-zirconia based sol-gel matrix under UV or IR laser irradiation ensures effective suppression of corrosion at the damaged sites at the surface of the coating. The possibility of controlling the release properties of polyelectrolyte containers by tuning the illumination wavelength and intensity of the incident laser beam makes the proposed method to be a versatile tool for corrosion protection. 

H. Brandtstadter, M. Braune, I. Schebesch, and H. Engel. Experimental study of the dynamics of spiral pairs in light-sensitive Belousov-Zhabotinskii media using an open-gel reactor. Chem. Phys. Lett., 322.-145—154, 2000. 

The light-sensitive BZ reaction demonstrates all basic features of excitable media of quite different nature and represents a very suitable experimental system to study controlled motion of spiral waves. In the experiments reported below an open gel reactor is used [29-31]. The catalyst is immobilized in a silicahydrogel layer of 0.5 mm thickness prepared on a plate... 

FIGURE 5.76 Preparation of PNIPAAm gel containing light-sensitive chiomophore, trisodium salt of copper chlorophyllin. Chlorophyllin has a double bond through which it enters the polymer network forming covalent bonds. The formed gel collapses under illumination. (After Suzuki, A. and Tanaka, T. 1990. Nature, 346, 345. With... 

HMiS Health 2, Flammability 0, Reactivity 0 Storage Light-sensitive Uses Preservative, bactericide, topical antiseptic, antimicrobial for cosmetics, shampoos, liq. soaps, creams/lotions, bath gels, bubble baths, pharmaceuticals, mouthwashes, feminine hygiene sprays, surgical scrubs/wipes/lubricants pet shampoos, teat dips skin sterilizing agent antiplaque dental prods. 

SCP and SCG, were able to shrink or expand, as long as these materials were stimulated. When light-sensitive groups were incorporated into the material, the thermally-triggered SCC of these systems could be extended to light as stimulus. Here, intelligent gels, polymer networks, in which the photomechanical effect was enhanced, and LCE, in which the SCC was based on the reorientation of macro-scopically ordered LC domains, were differentiated and examples were presented. 

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