Location is everything for plant cell differentiation

While the fate of most human cells is determined by their lineage—for example, renal stem cells go on to form the kidney while cardiac progenitor cells form the heart—plant cells are a little more flexible. Research shows ...

Wristbands do a health check while you work out

Next-generation fitness sensors could give deeper insights into human health through noninvasive testing of bodily fluids. A stretchy patch developed at KAUST could help this approach by making it easier to analyze sweat ...

Tiny light-up barcodes identify molecules by their twinkling

An imaging technique developed at Duke University could make it possible to peer inside cells and watch dozens of different molecules in action at once—by labeling them with short strands of light-up DNA that blink on and ...

Smarter drug release thanks to control over encapsulation

Researchers at Eindhoven University of Technology and Utrecht University have discovered the parameters that govern the encapsulation of drugs. This gives more control over the slow and steady release of drugs in patients. ...

Video: How hair dye works

Whether you need a disguise to run from the law or are just trying to emulate *NSYNC-era frosted tips, you may need some chemical assistance to put the hue in your do.

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Dye

A dye is a colored substance that has an affinity to the substrate to which it is being applied. The dye is generally applied in an aqueous solution, and requires a mordant to improve the fastness of the dye on the fiber.

Both dyes and pigments appear to be colored because they absorb some wavelengths of light more than others. In contrast with a dye, a pigment generally is insoluble, and has no affinity for the substrate. Some dyes can be precipitated with an inert salt to produce a lake pigment, and based on the salt used they could be aluminum lake, calcium lake or barium lake pigments.

Dyed flax fibers have been found in the Republic of Georgia dated back in a prehistoric cave to 36,000 BP. Archaeological evidence shows that, particularly in India and Phoenicia, dyeing has been widely carried out for over 5000 years. The dyes were obtained from animal, vegetable or mineral origin, with no or very little processing. By far the greatest source of dyes has been from the plant kingdom, notably roots, berries, bark, leaves and wood, but only a few have ever been used on a commercial scale.

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