Dyes, artificial

The list of everyday products made from organic compounds is very long. It includes drugs, artificial fibers, dyes, artificial colors and flavors, food additives, cosmetics, plastics of all kinds, detergents, synthetic rubber, adhesives, antifreeze, pesticides and herbicides, synthetic fuels, and refrigerants. 

Benzyl chloride is used in the manufacture of dyes, artificial resins, tanning agents, pharmaceuticals, plasticizers, perfumes, lubricants, and miscellaneous benyl compounds. 

Other compounds of food significance that have recently been the focus of attention using ME-AD approach are dyes. Artificial dyes are commonly added to foodstuffs with the purpose of enhancing their attractiveness. Since almost all of these additives are prepared by chemical synthesis, their presence in foods is the cause of extensive consumer mistrust since they may lead to adverse health effects and because their consumption is regulated by law. A rapid analysis of azo-dyes in food by using ME-AD has been reported [33]. Eive azodyes (yellow AB, Red 2G, Sunset Yellow, New Coccine, and Amaranth) were separated in less than 300 s and determined in soft drinks (liquid sample) and candies (solid sample), both with minimal sample preparation but still performed off chip. ... 

This paper describes the result obtained in a study of AFCEN (French Society for Design and Construction Rules for Nuclear Island Components) in order to characterize dye penetrant product family, based on experimental test methods of french standards NFA 09.520 and NFA 09.521. In particular, sensitivity tests have been carried out on artificial defects, and correlated with tests on real defects. Some tests on penetrant washability have also been performed. The results obtained with these three series of tests show that the choiee of a dye penetrant product family is not without influency on results obtained, and that is not so simple to make the good choice which could, in certain cases, be the less bad compromise. 

Additional regulations that provide specific requirements for color additives in foods are found in other parts of the CFR. Labeling of food products is found at 21 CFR 101.22(k). Color additives are sometimes called artificial colors or artificial colorings [21 CFR 101.22(a) (4)]. From a regulatory standpoint, a colorant is a dye or pigment used in a food contact material such as a polymer that does not migrate to food. Such materials are regulated as food additives [21 CFR 178.3297(a)], not as color additives. ... 

Direct observation of molecular diffusion is the most powerful approach to evaluate the bilayer fluidity and molecular diffusivity. Recent advances in optics and CCD devices enable us to detect and track the diffusive motion of a single molecule with an optical microscope. Usually, a fluorescent dye, gold nanoparticle, or fluorescent microsphere is used to label the target molecule in order to visualize it in the microscope [31-33]. By tracking the diffusive motion of the labeled-molecule in an artificial lipid bilayer, random Brownian motion was clearly observed (Figure 13.3) [31]. As already mentioned, the artificial lipid bilayer can be treated as a two-dimensional fluid. Thus, an analysis for a two-dimensional random walk can be applied. Each trajectory observed on the microscope is then numerically analyzed by a simple relationship between the displacement, r, and time interval, T,... 

The use of dyes seems to have began over 10 millennia ago, when dyes of vegetable origin were apparently applied to the skin simply for amusement, for ritual purposes, or to identify or differentiate status or social group. All the dyes used in the past and up to the nineteenth century, when artificial dyes were first synthesized, were of natural origin most were extracted from plants, some from animals (Verhecken 2005). Common dyes well known since antiquity are listed in Table 92 (Kirby 1988 Celoria 1971). 

Many other properties have to be considered, especially for apparel fibres, e.g., moisture absorption, ability to dye, drape, texture, weaving characteristics, etc. Many of the properties are influenced by the cross-section profile of the fibre. Thus cotton and some rayons (an artificial synthetic fibre derived from cellulose) are a hollow round fibre silk has a triangular shape giving it a fine lustre and drape. 

Kirstein, S. and Daehne, S. (2006). J-aggregates of amphiphilic cyanine dyes self-organization of artificial light harvesting complexes. Int. J. Photoenergy 5, 1-21. 

Scheme 2. Molecular structures of some photodynamically active and inactive dyes which have been employed as potential (artificial) bluelight photoreceptors...

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